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Arthroplasty of the Distal Radioulnar Joint Using a New Ulnar Head Endoprosthesis: Preliminary Report
Arthroplasty of the Distal Radioulnar Joint Using a New Ulnar Head Endoprosthesis: Preliminary Report Andrew A. Willis, MD, Richard A. Berger, MD, PhD, William P. Cooney III, MD From the Mayo Clinic and Mayo Foundation, Rochester, MN.
Purpose: To report our experience using a distal ulnar head endoprosthesis to treat painful disorders of the distal radioulnar joint (DRUJ) secondary to (1) instability and (2) arthrosis. Methods: Our experience with over 2 years of follow-up study consists of 19 wrists (17 patients). All patients presented complaining of pain and functional disability of the upper limb due to convergence instability or arthrosis of the DRUJ. The patients were studied prospectively. Thirteen patients had a total of 37 previous wrist or DRUJ surgical procedures. Standardized preoperative and postoperative assessments included a patient-reported pain score, a functional satisfaction score, forearm range of motion, grip strength as a percentage of that of the opposite limb, and clinical and radiographic examinations. The Mayo Wrist Score was calculated before surgery and at the last follow-up period. Results: Overall, pain scores decreased 50%, and functional satisfaction scores improved 3-fold. Average grip strength improved by 4 kg, or 16% from preoperative measurements. Forearm rotation was unchanged. All wrists were clinically stable on the latest follow-up examination. Two failures occurred early, at 7 and 14 months. Currently, all prostheses remain clinically and radiographically stable. Conclusions: Implant arthroplasty of the distal ulna combined with an adequate soft-tissue repair is recommended to improve pain, function, and strength of the wrist and forearm. Prosthetic replacement of the distal ulna restored stability to the DRUJ in patients with partial or complete excision of the ulnar head or DRUJ arthrosis and corrected radioulnar impingement. Incidences of complications or revision surgery to date have been low. Larger clinical and radiographic assessments will be needed to determine the long-term success of distal ulna prosthetic replacement. (J Hand Surg 2007;32A:177–189. Copyright © 2007 by the American Society for Surgery of the Hand.) Type of study/level of evidence: Therapeutic IV. Key words: Arthroplasty, distal radioulnar joint, ulnar head prosthesis, distal ulnar resection.
n intact distal radial ulnar joint (DRUJ) is critical to stability and load transmission in the wrist and forearm. Chronic instability and arthritic change at the DRUJ can lead to pain, decreased forearm rotation, diminished grip strength, and inability to perform gainful employment activities.1 Resection of the distal ulna has been used to treat these problems, and favorable results have been reported.2,3 It is increasingly recognized, however, that removal of the ulnar head has the potential to destabilize the forearm as well as the wrist. Complications after the distal ulnar resection (Darrach pro-
A
cedure) are not uncommon, especially mechanical impingement of the distal ulna against the radius.4 –9 In most patients this instability is associated with pain on stress loading of the upper limb, weakening of grip, loss of forearm rotation, and diminished lifting capacity.10 –12 Functional disability after distal ulnar resection can be considerable, and often the resulting symptoms can be worse than if surgery had not been performed at all.5,6 Patients who have painful instability after resection arthroplasty of the distal ulna present a difficult challenge. Several reconstructive procedures, includThe Journal of Hand Surgery
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ing tenodesis,13,14 a tethering procedure using tendon graft,15 partial head resection with or without softtissue interposition,16,17 and fusion of the distal radius and ulna with creation of a proximal pseudarthrosis,18 have been developed as alternatives or supplements to the Darrach procedure in an attempt to prevent complications associated with ulnar instability. These procedures, however, tend to be unpredictable in relieving pain, preventing radioulnar impingement, and providing a stable forearm. Furthermore, some of these techniques can cause the very same instability that they were designed to avoid.5,9 The intact DRUJ resists both tensile and compression loads in the wrist and forearm10 –21 and helps maintain a correct axis of rotation for the forearm.21–23 Resection of the ulnar head has been shown to cause a 3-dimensional instability, especially in the axial and transverse planes.22–24 To restore stability to the upper limb after resection arthroplasty of the DRUJ, we believe that it is necessary to (1) insert a mechanical spacer that is able to realign the forearm bones and resist pressure loads applied to the ulna and (2) reconstruct the soft-tissue attachments between the radius, ulna, and carpus to resist tensile forces in the forearm and wrist. We report the outcomes of a series of 17 consecutive patients (N ⫽ 19 wrists) treated at our institution who had metallic implant arthroplasty of the distal ulna using an endoprosthesis (uHead endoprosthesis, Small Bone Innovations, New York, NY). Implant arthroplasty was performed (1) as a salvage procedure for painful DRUJ instability after distal ulnar resection arthroplasty and (2) as a primary procedure for painful DRUJ arthrosis. Institutional review board approval was obtained to study this patient cohort.
Materials and Methods Prosthetic Design The ulnar head prosthesis that we used (uHead endoprosthesis, Small Bone Innovations) is a modular endoprosthesis that consists of a metal stem with a shaft that can be press-fit or cemented into the intramedullary canal of the distal ulna (Fig. 1). A metal semispheric ulnar head of cobalt– chrome alloy is connected to an intramedullary stem of cobalt– chrome alloy with a commercially pure titanium sprayed finish through a tight-fit Morse-taper junction. There are 2 stem-neck designs: an extended collar for revision of previous distal ulna complete resection and a normal collar for primary procedures
Figure 1. Ulnar head prosthesis. (A) The prosthesis has an intramedullary component (left) and an articulating head (right). (B) There are 2 stem options. Top: Extended collar, which is used in revision procedures such as previous distal ulna resection. Bottom: Normal stem and collar, which can be used in primary procedures calling for ulna head removal and also for the revision of failed partial distal ulna head excisions.
calling for ulnar head excision and for revision of failed distal ulnar head resection procedures (Fig. 1B). The head has a provision for fixation of the triangular fibrocartilage complex (TFCC) and extensor carpi ulnaris (ECU) subsheath to the device by way of sutures, which we believe is advantageous for initial soft-tissue stabilization (Fig. 2). To ensure adequate length correction after previous surgery, differently sized ulnar head components and extended collars are available to compensate for shortening of the ulna after ulnar head resection. Surgical Technique The surgical technique uses a dorsal skin incision centered over the DRUJ in line with the fourth metacarpal. The full technique is described in detail in a separate publication.25 Briefly, a midline ulnar (medial) incision can be used primarily or after a previous distal ulna procedure. The extensor retinaculum is identified and divided through the fifth extensor compartment. A dorsoulnar-based capsuloretinacular flap is raised at the level of the fourth extensor compartment and dissected carefully in an ulnar direction to the base of the sixth compartment. The ECU subsheath and ECU tendon are left in place and elevated subperiosteally in a radial-to-ulnar direction as a capsular subperiosteal flap. The TFCC is left in continuity with the ECU subsheath as they are carefully freed from the distal ulna. With guidance from
Willis, Berger, and Cooney / Prosthetic Replacement, Distal Ulna
Figure 2. (A) The ulnar head prosthesis provides for fixation of the soft-tissue supports of the DRUJ. Sutures from ECU subsheath and TFCC to ulnar head are shown. (B) Detailed ECU and TFCC repair with the articulated ulnar head and soft-tissue attachment. © Mayo Foundation.
preoperative templated x-rays and an intraoperative resection guide that is used to determine the correct length of the implant, an osteotomy is made through the distal third of the ulna. After removal of the ulnar head, the sigmoid notch is inspected for incongruity or bone spurs and is contoured appropriately with a burr if needed. If there is a peripheral TFC tear, suture repair with a 3-0 nonabsorbable suture is performed, and the suture end is attached to the ulnar side of the prosthesis ulnar head at a later stage in the procedure (Fig. 2). For preparation of prosthesis insertion, the intramedullary canal of the distal ulna is reamed with increased-diameter broaches to the appropriately sized implant stem. Stem size is determined from radiolucent templates placed over the distal ulna, with magnification controlled. A trial prosthesis is used to check the size of the head and stem that restores optimum length and stability. Biplanar imaging is used to match ulna length and fit with the sigmoid fossa of the distal radius. Ulnaneutral or slight ulnaminus variance is recommended with respect to the length of the distal radius and ulna
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head replacement. Care is taken to match the ulna head size by templating to the opposite unaffected ulna head when possible. Depending on bone quality, the prosthesis is either press-fit or cemented. Cementing the prosthesis is recommended in case of previous wrist fusion or osteoporotic bone. Soft-tissue repair is an important component in the surgical procedure to provide temporary stabilization of the prosthesis within the DRUJ. The triangular fibrocartilage (TFC), ECU subsheath, and ulnar capsule are secured to the metallic ulna head directly with 2-0 or 3-0 nonabsorbable sutures to promote formation of a stable soft-tissue envelope about the prosthesis (Fig. 2). The ECU sheath is sutured proximal to the sutures for the TFC. The position of the ulna head is located on the Morse-taper of the stem to place the ulna head holes dorsal medial (Fig. 3). The soft-tissue repair to the ulna head is performed before connecting the ulna head to the stem of the prosthesis. In addition, an extended collar of variable sizes can be used to restore ulnar length after a previous complete distal ulna resection (Fig. 1B). Soft-tissue closure using the capsuloretinacular flap is performed with reattachment of the soft-tissue flap to the dorsal rim of the sigmoid fossa of the distal radius. Sufficient tension is used to ensure stability of the DRUJ. The repair is performed by direct suture, with drill holes dorsally on the sigmoid fossa or with suture anchors. Stability is augmented as required with local tissue and in some cases with a strip of the flexor carpi ulnaris (FCU) tendon that is left attached distally to the pisiform and brought across the waist of the ulnar head prosthesis where it is attached by suture anchor to the distal radius.
Figure 3. Repair of the soft tissues (ECU subsheath and TFC) to the ulna head prosthesis. The ECU tendon and subsheath are shown with a suture in the ECU tendon (held by hemostat) secured to dorsal-ulnar aspect of the ulna head prosthesis. © Mayo Foundation.
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Table I. Preoperative Clinical and Radiographic Characteristics of Study Population: Ulnar Head Arthroplasty Gender
Age, y
1
F
62
Repetitive microtrauma (overuse)
None
2
F
32
Trauma (DRUJ dislocation)
Sauve-Kapandji
3
M
53
Trauma (SLAC wrist)
4
F
39
Trauma (LT dissociation)
Partial wrist fusion, complete wrist fusion, Darrach, revision Darrach, interposition arthroplasty Partial wrist fusion (n ⫽ 3)
5
F
43
Trauma (distal radius malunion)
6
M
72
7
M
8
Original DRUJ Injury
Prior Surgery
Complaint
Physical Examination
Imaging
Ulnar-sided wrist pain, esp with forearm rotation Ulnar-sided wrist pain, esp with forearm rotation Ulnar-sided wrist pain, ulnar stump instability
DRUJ tenderness, crepitance, dorsal ulnar prominence
X-ray: DRUJ sclerosis, osteophytes
Piano-key sign, RU impingement pain (compression, grip)
Ulnar-sided wrist pain, grip weakness
DRUJ tenderness, pain with compression
Berger-Adams stabilization procedure
Ulnar-sided wrist pain, forearm motion loss
Rheumatoid arthritis
Wrist arthroscopy, AIN/PIN neurectomy
Ulnar-sided wrist pain, rheumatoid arthritis
DRUJ tenderness, piano-key sign, pain with compression, dorsal ulnar prominence DRUJ tenderness, crepitance
X-ray: Sauve-Kapandji pseudarthrosis; CT: radioulnar convergence X-ray: wrist arthrodesis, resection distal ulna; stress x-ray: radioulnar convergence X-ray: partial wrist arthrodesis, positive ulnar variance X-ray: DR malunion, DRUJ osteophytes
70
Trauma (DRUJ dislocation)
Darrach
Ulnar-sided wrist pain, grip weakness
Piano-key sign, RU impingement pain (compression, grip)
F
45
Repetitive microtrauma (overuse)
Ulnar-sided wrist pain
DRUJ tenderness, crepitance, piano-key sign
9
M
67
Psoriatic arthritis
Ulnar shortening, HIT arthroplasty; median nerve harvest for tendon interposition None
Ulnar-sided wrist pain, psoriatic arthritis
DRUJ tenderness, pain with compression
10
F
45
Trauma (distal radius fracture)
None
Ulnar-sided wrist pain, esp with forearm rotation
11
M
49
Trauma (fall on wrist)
Darrach
12
F
34
Repetitive microtrauma (overuse)
Darrach, revision Darrach, soft-tissue stabilization (n ⫽ 3), ulnar lengthening, interposition arthroplasty
Ulnar-sided wrist pain, ulnar stump instability Ulnar-sided wrist pain, ulnar stump instability
DRUJ tenderness, crepitance, piano-key sign, RU impingement pain (compression, grip) Piano-key sign, RU impingement pain (compression, grip)
Piano-key sign, RU impingement pain (compression, grip)
Piano-key sign, RU impingement pain (compression, grip)
X-ray: pancarpal DJD; MRI: eburnation ulnar head, sigmoid notch X-ray: radiocarpal DJD, resection distal ulna, radioulnar convergence X-ray: resection distal ulna; stress x-ray: radioulnar convergence X-ray: radiocarpal, DRUJ sclerosis; CT: dorsal subluxation ulnar head X-ray: DRUJ diastasis, sclerosis, subchondral cysts X-ray: partial resection distal ulna; stress x-ray: radioulnar convergence X-ray: resection distal ulna; stress x-ray: radioulnar convergence
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Pt. No.
Table I. Continued Gender
Age, y
13
F
50
Trauma (chronic Essex-Lopreste)
14
M
35
14
M
15
Original DRUJ Injury
Prior Surgery
Complaint
Physical Examination
Imaging
Ulnar-sided wrist pain, esp with forearm rotation
DRUJ tenderness, crepitance, piano-key sign, pain with compression
X-ray: positive ulnar variance, ulnar head subchondral cysts
Rheumatoid arthritis
Ulnar shortening, soft-tissue stabilization, revision ulnar shortening, interposition arthroplasty None
36
Rheumatoid arthritis
AIN/PIN neurectomy
M
75
Repetitive microtrauma (overuse)
None
15
M
75
Repetitive microtrauma (overuse)
None
16
F
48
Trauma (SLAC wrist)
Complete wrist fusion, PIN neurectomy, soft-tissue stabilization
Ulnar-sided wrist pain, rheumatoid arthritis Ulnar-sided wrist pain, rheumatoid arthritis Ulnar-sided wrist pain, esp with forearm rotation Ulnar-sided wrist pain, esp with forearm rotation Ulnar-sided wrist pain, esp with forearm rotation
DRUJ tenderness, pain with compression DRUJ tenderness, pain with compression DRUJ tenderness, pain with compression, dorsal ulnar prominence DRUJ tenderness, pain with compression, dorsal ulnar prominence DRUJ tenderness, crepitance, piano-key sign, pain with compression
17
M
39
Trauma (fall on wrist)
Partial wrist fusion, ulnar styloidectomy
Ulnar-sided wrist pain
DRUJ tenderness, crepitance, pain with compression
X-ray: radiocarpal DJD, DRUJ dissociation X-ray: pancarpal DJD, DRUJ dissociation X-ray: radiocarpal, DRUJ sclerosis, positive ulnar variance X-ray: radiocarpal, DRUJ sclerosis, positive ulnar variance X-ray: wrist arthrodesis, dorsal subluxation ulnar head, DRUJ sclerosis; BS: increased signal at DRUJ X-ray: partial wrist fusion; DRUJ subluxation
AIN, anterior interosseous nerve; CT, computed tomography; DJD, degenerative joint disease; DR, dorsoradial; esp, especially; HIT, hemiresection interposition; LT, Lunotriquetal; MRI, magnetic resonance imaging; PIN, posterior interosseous nerve; pt, patient; RU, radioulnar.
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Pt. No.
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Stability of the DRUJ after the soft-tissue repair can be judged at surgery by stressing the DRUJ dorsal and palmarly and by assessing stability during forearm pronation and supination. Other soft-tissue augmentation beside the capsule alone or with the FCU tenodesis was performed in 1 patient for whom fascia lata was used to augment a deficient capsule. After capsule closure, the extensor retinaculum is closed over the capsule, restoring the normal anatomic position of the extensor tendons. After surgery, the forearm is immobilized in midrotation and held in a supportive long-arm splint or cast for 4 to 6 weeks, depending on assessment of DRUJ stability at the time of surgery. Usually 4 weeks after surgery the cast is removed and the patient is placed into a removal muenster-type splint that allows for elbow flexion– extension but controls forearm rotation. Active ranges of motion of the wrist and forearm are initiated between 4 and 6 weeks, depending on the soft-tissue repair and intraoperative stability of the arthroplasty. When the patient has achieved 45° of pronation and 45° of supination, the forearm support splint is discontinued and therapy is advanced as tolerated. At 8 weeks, therapy incorporates strengthening exercises, and the patient
is then allowed to gradually return to normal activities. Patient Series Nineteen ulnar head arthroplasties have been performed in 17 patients using the endoprosthesis (uHead endoprosthesis, Small Bone Innovations) (Table 1). The average follow-up period has been 32 months (range, 26 – 60 mo). There were 8 men and 9 women with an average age of 51 years (range, 32–75 y). The dominant extremity was involved in 8 cases. Seven patients were manual laborers by trade (Fig. 4), and 1 patient was receiving workers’ compensation related to the DRUJ injury. All patients presented with complaints of pain with activity using the affected limb and debilitating functional impairment. Indications for ulnar arthroplasty were distal ulnar instability (and/or radioulnar impingement) (Fig. 5) after resection of the ulnar head (6 wrists) or DRUJ arthrosis (11 wrists) and inflammatory arthritis (2 wrists). The original injury to the DRUJ was trauma related in 12 wrists, repetitive overuse with instability in 5 wrists; there was 1 patient with rheumatoid arthritis and 1 patient with psoriatic arthritis. Thirteen patients had a total of 37 previous surgeries
Figure 4. (A) A PA radiograph of a 50-year-old manual laborer with radiocarpal arthritis, ulnocarpal impaction, and painful motion at the DRUJ. (B) A PA close-up view and (C) full-length view of the wrist after radioscapholunate fusion combined with distal ulna resection and ulnar head replacement; surgical staples removed. Stable distal ulna with mild ulnocarpal impingement and slight resorption at ulna head–shaft junction secondary to stress shielding. (D) Lateral view of the wrist at 28 months. Patient has returned to work with absence of pain and 80% normal forearm rotation. © Mayo Foundation.
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Figure 5. Clinical case of radioulnar impingement with failed distal ulna resection. (A) A PA view the showing area of impingement (scalloping distal radius). (B) Lateral view with mild to moderate dorsal displacement of the distal ulna. (C) Postoperative PA view in plastic cast of the ulnar head replacement articulating joint inferior to the sigmoid notch. After 3 years, (D) PA and (E) lateral views of the right wrist shows a stable DRUJ without impingement. There is mild ulna head–shaft bone resorption with no evidence of implant loosening. © Mayo Foundation.
related to the distal ulna and DRUJ, with an average of 2.8 (range, 1–5) surgeries per patient. Previous surgery included 6 Darrach resections,2 1 SauveKapandji procedure,18 1 Bowers hemiresection interposition procedure,16 6 soft-tissue stabilizations,6 3 interpositional arthroplasties of the DRUJ with either the pronator quadratus muscle29 or allograft fascia lata, 3 ulnar-shortening procedures, and 1 ulnarlengthening procedure. There were 5 partial and 2 complete wrist fusions. In the 6 wrists with symptomatic distal ulnar instability, 4 were secondary to a previous Darrach procedure, 1 was secondary to a
previous Sauve-Kapandji procedure with proximal instability, and 1 was secondary to a previous Bower’s procedure. Subsequently, 2 patients had revision Darrach procedures, and 1 patient had had 3 previous soft-tissue stabilizations of the ulnar stump. Two patients had prior interpositional arthroplasty of the DRUJ with fascia lata allograft, and 1 patient had an ulnar-lengthening procedure in an attempt to relieve the painful instability resulting from the original procedure (all without improvement). All patients in this study were subject to standardized preoperative and postoperative assessments.
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Table 2. Verbal Analog Pain Scale Pain
Strength Value
No pain Pain with strenuous activity Pain with high activity Severe pain without activity
1 2 3 4
From van Schoonhoven et al.26
Pain was evaluated with a verbal analog pain scale ranging from 1 to 4 points, similar to that described by van Schoonhoven (Table 2)26: 4, patient was very satisfied with the function of the hand and arm; 3, patient was satisfied with the function of the hand and arm; 2, patient was somewhat satisfied with the function of the hand and arm and during the postoperative assessment rated it as only fair or improved compared with the preoperative status; and 1, patient was not satisfied with the function of the hand and arm and during the postoperative assessment rated it as the same or worse than before surgery. The Mayo Wrist Score (Table 3) applied to conditions affecting the DRUJ was applied to patients before and after surgery for pain, functional status (return to work), range of forearm rotation, and grip strength. A score of 90 to 100 was excellent; 80 to 89, good; 65 to 79, fair; and les than 65, poor. In the 2 bilateral cases, the scores for motion and grip were based on healthy age- and gender-matched controls. Forearm motion (rotation) was recorded as the degrees of pronation and supination from the neutral position. Grip strength was measured using a dynamometer (Jamar dynamometer; Preston, Cambridge, MA) and was recorded as a percentage of that of the opposite limb. Clinical examination included assessment of DRUJ tenderness by direct palpation, the presence of a positive piano-key sign indicating anterior–posterior instability of the ulna, the presence of radioulnar convergence impingement or DRUJ pain on manual compression testing, and DRUJ crepitus on forearm rotation. Forearm stability and DRUJ arthritis were also assessed radiographically by posteroanterior (PA) x-rays and a lateral x-ray in midforearm rotation. Before surgery, dorsal displacement of the ulna (as recorded on lateral x-rays from neutral alignment), proximal radioulnar impingement (as evidenced by scalloping of the radius on PA radiograph), and degenerative changes of the ulnar head or sigmoid notch (noted as loss of joint cartilage at the DRUJ) were recorded. After surgery, the latest radiographs were examined and recorded for signs of
recurrent instability (percentage of dorsal displacement of the ulna), loosening of the prosthetic stem (⬎2 mm of lucency around the prosthesis stem), or bony reactions within the sigmoid fossa or distal ulna. At the time of the initial procedure, 13 stems were press-fit and 6 were cemented. The cemented prostheses were used in cases of previous wrist fusions and in rheumatoid disease or osteoporotic bone. Three extended collars were required to compensate for previous excessive resection of the distal ulna. All 13 wrists with an intact ulnar head had degenerative wear of the ulnar head confirmed at the time of surgery. Seven wrists also had degenerative changes Table 3. Mayo Wrist Score Category Pain (25 points)
Functional status (25 points)
Score, Points 25 20 15 0 25 20 15 0
Range of motion (25 points)
25 15 10 5 0
None Mild, occasional Moderate, tolerable Severe or intolerable Returned to regular employment Restricted employment Able to work but unemployed Unable to work because of pain Percentage of normal 100
25
75–99 50–74 25–49 0–24 Flexion–extension arc,° (injured hand only) ⱖ120 91–119 61–90 31–60 ⱕ30 % of normal 100
15 10 5 0
75–99 50–74 25–49 0–24
Excellent Good Fair Poor
90–100 80–89 65–79 ⬍65
25 15 10 5 0 Grip strength (25 points)
Findings
Final Result
From Bradway JK et al,31 Berger and Cooney,32 and Cooney et al.33
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Table 4. Comparison of Preoperative and Postoperative Outcome Measures Mean (SD) Outcome
n
Pain Forearm supination Forearm pronation Forearm rotation arc Grip strength, % Mayo Wrist Score
19 18 18 18 15 19
Before Surgery 3.6 60.8 74.4 135.3 75 41
(0.5) (30.2) (14) (37.8) (29) (16)
Median (min, max)
After Surgery
Before Surgery
1.8 60 71.7 131.7 73 77
4 67.5 70 135 68 45
(1) (23.8) (15) (31.6) (21) (13)
(3, 4) (⫺10, 90) (55, 90) (60, 180) (33, 147) (15, 70)
After Surgery 2 72.5 75 145 83 75
(1, 4) (10, 80) (45, 90) (80, 170) (40, 108) (55, 95)
p ⬍.01* .90† .51† .65† .83† ⬍.01†
Paired t tests were used to compare the preoperative and postoperative values of grip strength and the forearm rotation measures. Because pain is distributed as an ordinal variable, it was compared with a (nonparametric) signed rank test. All statistical tests were 2-sided, and p values less than .05 were considered significant. *Signed rank test. †Paired t test.
present within the sigmoid notch. These degenerative changes were treated by smoothing and rounding off the sigmoid notch with a small acorn-shaped burr. Three wrists required additional soft-tissue reconstructions with Linscheid-Hui procedure.14 Stability, as judged clinically, was restored in all patients at the time of surgery, based on assessment of the dorsal– volar displacement in both forearm pronation and supination. Statistical Analysis To assess the significant differences between preoperative and postoperative outcomes in grip strength and forearm rotation, a paired t test was performed (Table 4). To measure pain differences, a nonparametric signed rank test was performed. All statistical tests were 2-sided, and p values less than .05 were considered significant. In addition, the preoperative and postoperative Mayo Wrist Scores were statistically assessed with a nonparametric t test.
Results Clinical Results Seventeen patients who had ulnar arthroplasty of the DRUJ in 19 wrists stated that they were improved after this procedure and would have the surgery performed again. Eighteen of 19 wrists reported having improved pain compared with the preoperative status. All patients had pain relief at rest; 5 patients had mild pain with activity, but this was improved from the preoperative pain level. Pain scores decreased from a preoperative mean level of 3.6 to a postoperative mean level of 1.8 (a 50% reduction in patient-reported pain scores). The improvement in pain was statistically significant (Table 4). The 1 patient who had persistent pain with activities had sigmoid notch arthrosis with degenerative changes
involving the entire ulnar head at the time of surgery. She also had had a previous wrist arthrodesis. Because her DRUJ pain did not improve, she subsequently was treated with a custom arthroplasty of the DRUJ (replacement of the sigmoid fossa with a polyethylene–metal resurfacing implant and standard distal ulna prosthesis). She had a successful outcome at 2 years after surgery. In this series of 19 wrists, hand and arm functional satisfaction scores improved from a preoperative mean level of 1.1 to a postoperative mean level of 3.3. This represents a 3-fold overall improvement in patient-reported satisfaction scores with upper-limb function. Only 1 patient was completely unsatisfied with the functional outcome of the ulnar head arthroplasty procedure (noted earlier). Two patients were only partially satisfied. Of these, one has painful forearm rotation with extended use and moderate grip weakness. The other patient has global wrist pain and weakness not clearly related to the DRUJ, which remains clinically and radiographically stable. Grip strength improved from a preoperative mean of 67% of the opposite limb to a postoperative mean of 83%. After surgery, there was an average improvement in grip strength of 4 kg compared with preoperative values. The change in grip was statistically significant based on the strength of the opposite limb (Table 4). Forearm arc of motion was unchanged. Supination had a preoperative mean of 60° compared with a postoperative average of 60° and median of 67° to 72°. Pronation had a preoperative average of 70° and a postoperative average of 75°. Changes in forearm rotation were not statistically significant. The Mayo Wrist Score improved from a preoperative mean of 40 (range, 15–70) to a postoperative mean of 77
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Table 5. Postoperative Wrist Scores and Follow-Up Periods
Pt No.
Preop Wrist Score
Postop Wrist Score
Overall Delta Outcome
1 2
40 40
75 70
35 30
3 4
20 45
70 55
35 10
5 6 7 8 9 10 11 12 13 14
15 55 45 35 45 65 40 15 15 70
80 95 85 75 75 95 95 75 65 80
65 40 40 40 30 30 45 65 50 10
None Ulna diaphysis; fracture healed Fair None Poor Ulnar neuropathy persistent Good None Excellent None Good None Good Ulnar neuropathy resolved Good None Excellent None Excellent None Fair None Fair None Good Unstable painful DRUJ
15 15 16
50 45 30
85 80 75
35 35 55
Good Good Good
None None Loosening ⫹ arthritis DRUJ
17
50
90
40
Good
Loosening
Complications
Good Fair
Revision Surgery
Length of Follow-Up Period, mo
None None
21 48
None None
72 16
None None None None None None None None None Free palmaris graft reconstruction None None Cemented distal ulna, custom sigmoid fossa Cemented distal ulna
12 36 24 (pt deceased) 16 (pt in prison) 16 45 37 15 36 41 18⫹⫹ ____? 24†
25†
Postop, postoperative; preop, preoperative; pt, patient. *Indicates result after revision surgery. †Indicates length of follow-up study after revision surgery.
(range, 55–95) (Table 5). Based on the Mayo Wrist Score there was a mean improvement of 35 points (range, 10 –55). The improvement in the Mayo Wrist Score was statistically significant (Table 4). No wrist lost points. Based on the Wrist score there were 4 excellent, 10 good, 4 fair, and 1 poor results (Table 5). On clinical examination, 17 wrists had tenderness localized over the DRUJ before surgery, but mild tenderness was present in only 2 wrists after surgery. A positive piano-key sign was present in 10 wrists before surgery, and radioulnar impingement was present in 6 wrists that had had previous distal ulnar resection procedures. After surgery, 1 wrist had clinical signs of mild dorsal ulna instability. Radioulnar impingement pain in 6 patients before surgery was completely corrected. Seven wrists had painful crepitus on forearm rotation during examination before surgery; 2 wrists had painless crepitance on forearm rotation after surgery. Eight of 13 wrists with DRUJ arthrosis before surgery had a markedly positive radioulna compression test. Only 1 wrist with sigmoid notch arthrosis (noted earlier) was had a positive compression test result after surgery.
Imaging Results Preoperative imaging with standard lateral radiographs showed gross distal ulnar instability in 5 of the 6 wrists with previous ulnar head excision. Radioulnar impingement with scalloping of the radius was also noted (Fig. 5). One patient with a previous Bowers procedure16 had convergence instability only on dynamic stress imaging. Ten of 12 wrists with symptoms of arthrosis of the intact DRUJ had clear arthritic changes on radiographic imaging before surgery. Nineteen of 19 wrists were radiographically stable at the latest postoperative assessments. Signs of remodeling of the sigmoid fossa were present around the metallic head. One patient had progressive degeneration of the sigmoid notch (mentioned earlier) and has had a revision surgical procedure. There was evidence of prosthetic loosening of the stem in 2 patients, both of whom had a successful revision with reinsertion of the prosthesis with bone cement. Five of 19 wrists had slight bone resorption (1–2 mm) beneath the collar of the prosthesis. This resorption, however, has stabilized
Willis, Berger, and Cooney / Prosthetic Replacement, Distal Ulna
and, at average 32 months of follow-up study, has not progressed. Complications Four patients had complications, 1 early and 3 late. There was 1 intraoperative nondisplaced fracture of the ulna in this series that occurred during canal preparation of the ulna diaphysis (early complication). This was related to impacting the broach rather than rasping with the broach. The fracture was stabilized with a 3.5-mm cortical screw proximal to the prosthesis. This patient has gone on to an otherwise uneventful recovery and is rated overall as an excellent outcome. Late complications include 1 patient with painful neuroma of the dorsal cutaneous branch of the ulnar nerve that has adversely affected her overall outcome. A second patient developed intermittent instability of the ulnar head prosthesis, which became symptomatic 5 months after surgery. This patient was determined later to have a clinical history of rheumatoid arthritis and, in retrospect, had a suboptimal soft-tissue envelope about the DRUJ. He had a concomitant wrist arthrodesis at the time of his ulnar head arthroplasty. Stability of the DRUJ was restored at revision surgery with a distally based strip of FCU tendon (Linscheid-Hui procedure).14 Currently, the prosthesis appears stable and the patient is doing well clinically. A third patient developed progressive degenerative changes of the sigmoid notch. He subsequently had a revision surgery to downsize the ulnar head and resurface the arthritic sigmoid notch. Two patients (mentioned earlier) had intramedullary stem loosening. The first patient developed proximal and distal osteolysis about a press-fit prosthetic stem with a windshield wiper configuration early in the postoperative course consistent with gross radiographic movement. Inadequate postoperative support and limb overuse with lifting appeared to be responsible factors. The prosthesis fixation was revised with bone cement. The second patient had a prior wrist fusion, which may have contributed to increased force across the DRUJ. Revision to a cemented stem was performed 14 months after surgery, and the prosthesis remains clinically and radiographically well fixed at 16 months after the revision procedure.
Discussion The concept of a replacement for the distal ulna is not new. Swanson27 developed a silicone ulnar head prosthesis as a means of alleviating complications after resection arthroplasty of the DRUJ and reported
187
good clinical outcomes using his prosthesis as a mechanical spacer. Stanley and Herbert28 showed that use of a silicon ulnar head prosthesis (Silastic) combined with a soft-tissue repair could relieve symptoms and restore stability even in manual laborers. Although preliminary results were encouraging, complications using this prosthesis, including dislocation, prosthetic fracture, and silicone synovitis, have led investigators to conclude that an alternative prosthesis is needed. As a result, newly designed and improved DRUJ prostheses have been developed that appear to be more mechanically durable and biologically compatible, to anticipate long-term success with clinical use. A metallic endoprosthetic design helps recreate the bony and soft-tissue anatomy of the DRUJ (Small Bone Innovation). Cadaveric studies have shown that new-generation implants can restore near-normal biomechanics and kinematics of the upper limb compared with the intact state.23,24 Ceramic and metallic ulnar head endoprostheses have been introduced into the clinical setting as a salvage procedure for patients with painful instability after failed resection arthroplasty of the DRUJ, but they may have primary indications in painful DRUJ related to rheumatoid arthritis and posttraumatic arthritis. Although there are relatively few studies in the literature, preliminary outcomes25,26 with ulnar head implants have been encouraging. Although resection arthroplasty of the distal ulnar head and related procedures can be an effective treatment for painful disorders of the DRUJ,2– 4 these procedures alter inherent mechanical function and load transmission of the DRUJ and not infrequently can cause secondary wrist and forearm instability.5,6,8 The use of an ulnar head prostheses has been shown in cadaveric laboratory studies22–24 to prevent radioulnar convergence, maintain the kinematic relationship of the radius and ulna during forearm rotation, resist subluxating forces, and accept longitudinal load transmission in the wrist and forearm. Preliminary clinical reports using different ulnar head prostheses as a salvage procedure for painful disorders of the DRUJ have been encouraging. Van Schoonhoven et al26 reported on 23 patients with debilitating pain and instability of the DRUJ after resection arthroplasty who were treated with a metallic endoprosthesis and ceramic ulnar head combined with a simple soft-tissue repair as a salvage procedure. After a minimum 2-year follow-up period, the researchers reported significant improvements in pain scores, satisfaction scores, forearm
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motion, and grip strength. There were no prosthetic failures; however, 1 patient required removal of the prosthesis because of low-grade infection. Scheker et al30 reported on 23 patients with persistent pain and dysfunction after failed resection arthroplasty of the DRUJ or posttraumatic arthritis of the DRUJ after treatment with a custom-designed constrained ball and socket-type DRUJ prosthesis. They reported that all patients had complete pain relief and regained good lifting capacity at a mean of 15 months after the procedure. There were no significant complications or prosthetic failures reported in this series. Similarly, Kapandji25 developed a balland-socket–type prosthesis and has reported 2 cases of good clinical results. Laboratory studies24,25 using a dynamic cadaveric forearm simulator have shown nearly identical 3-dimensional displacements of the distal ulna using an endoprosthesis compared with the intact state. Furthermore, biomechanic loading studies have shown a statistically significant improvement in radioulnar convergence toward the intact state with placement of the ulnar head compared with resection of the ulnar head. Although the principal indication for metallic implant arthroplasty of the DRUJ is a failed resection of the distal ulna, we believe that there can be a primary procedure (hemiarthroplasty) in patients with arthritic change at the DRUJ. We believe at this time, based on this preliminary review, that ulnar head arthroplasty can provide good pain relief in patients with either radioulnar convergence instability or DRUJ arthrosis. Including the successful revisions, 90% of patients received a reasonable degree of pain relief and all but 1 patient were functionally satisfied with the outcomes of this procedure. There were no problems of DRUJ instability that we attribute to the soft-tissue repair (ECU subsheath and TFC) to the head of the prosthesis. We believe that this technique provides added stability compared with those ulnar head prostheses that rely on a capsule–retinacular flap alone.26 There are limitations to this study. Most of our patients had several previous surgical interventions to treat a multitude of problems in the affected extremity. This study limited postoperative assessment to the DRUJ and may explain why the grip strength improved only 16% from preoperative measurements and did not reach the strength of the uninjured extremity. Similarly, improvement in rotational motion of the forearm did not occur but was maintained after ulnar head replacement. Patients with previous Darrach resection, for example, had pain and instability
but had only slight loss of forearm rotation. The ulnar head prosthesis was designed to improve stability and decrease pain and in patients with previous Darrach procedures; improvement in motion was not an expected goal. With respect to outcome, the Mayo Wrist Score showed an improvement of 40 points between the preoperative and postoperative assessments. Although not a validated score such as the Disabilities of the Arm, Shoulder, and Hand questionnaire or Patient-Related Wrist Evaluation, the change in the Mayo Wrist Score represents a statistically significant improvement in physician-observed and -measured wrist function. Further studies with such patient-related information would provide more support for the clinical effectiveness of prosthetic replacement of the distal ulna. Concern has been raised about the potential for compression pressure effects and progressive degeneration of the metallic ulnar head on the sigmoid notch. To date, we have not found this to be the case. Minor arthritic changes or structural alterations in the sigmoid notch have not resulted in poor clinical outcomes in the patients in this series. One patient of the 19, however, did not improve and has had a custom resurfacing arthroplasty of the sigmoid fossa. Radiographically, the sigmoid notch appears to adapt and remodels to the contour and forces imparted by the ulnar head, a finding seen by others. Van Schoonhoven et al,26 for example, using a ceramic ulnar head, found that sigmoid notch remodeling and progressive erosion and cyst formation at the sigmoid notch occurred in only 1 patient. Clinically, ulnar head replacement produced adequate pain relief and restoration of function in this patient population, even in those patients in whom the sigmoid fossa required surgical remodeling with a burr to correct deformity or to allow adequate seating of the prosthetic ulnar head. Our preliminary results show that distal ulna prosthetic replacement combined with adequate soft-tissue repair can reliably restore stability to the DRUJ. The metallic ulnar head has been designed with suture holes that allow for temporary fixation of the TFCC and ECU subsheath to promote anatomic positioning of a soft-tissue sleeve about the prosthesis. This repair of the TFCC and ECU subsheath to the prosthesis—although temporary—is an important part of the soft-tissue procedure. In addition, it is important during the surgical procedure to assess the soft-tissue stabilization of the prosthesis by the retaining capsule and, if necessary, to add soft-tissue
Willis, Berger, and Cooney / Prosthetic Replacement, Distal Ulna
support with a strip of the FCU or autograft tendon.13,14 Longer follow-up periods and more extended clinical use by multiple hand surgeons is required to determine the long-term value of prosthetic replacement of the distal ulna. Received for publication October 5, 2005; accepted in revised form December 6, 2006. Drs. R.A. Berger and Dr. W.P. Cooney received benefits from Small Bone Innovations (SBI), New York. Dr. W.P. Cooney has received commercial research grants from SBI and serves as a consultant. Corresponding author: William P. Cooney, MD, Mayo Clinic, 200 First St, SW, Department of Orthopedic Surgery, Rochester, MN 55902; e-mail: [email protected]. Copyright © 2007 by the American Society for Surgery of the Hand 0363-5023/07/32A02-0007$32.00/0 doi:10.1016/j.jhsa.2006.12.004
References 1. Dell PC. Distal radioulnar joint dysfunction. Hand Clin 1987;3:563–583. 2. Dingman PV. Resection of the distal end of the ulna (Darrach operation); an end result study of twenty four cases. J Bone Joint Surg 1952;34A:893–900. 3. Hartz CR, Beckenbaugh RD. Long-term results of resection of the distal ulna for post-traumatic conditions. J Trauma 1979;19:219 –226. 4. af Ekenstam EF, Engkvist O, Wadin K. Results from resection of the distal end of the ulna after fractures of the lower end of the radius. Scand J Plast Reconstr Surg 1982;16:177– 181. 5. Bell MJ, Hill RJ, McMurtry RY. Ulnar impingement syndrome. J Bone Joint Surg 1985;67B:126 –129. 6. Bieber EJ, Linscheid RL, Dobyns JH, Beckenbaugh RD. Failed distal ulna resections. J Hand Surg 1988;13A:193– 200. 7. Buck-Gramcko D. On the priorities of publication of some operative procedures on the distal end of the ulna. J Hand Surg 1990;15B:416 – 420. 8. Lees VC, Scheker LR. The radiological demonstration of dynamic ulnar impingement. J Hand Surg 1997;22B:448 – 450. 9. McKee MD, Richards RR. Dynamic radio-ulnar convergence after the Darrach procedure. J Bone Joint Surg 1996; 78B:413– 418. 10. Fernandez DL. Radial osteotomy and Bowers arthroplasty for malunited fractures of the distal end of the radius. J Bone Joint Surg 1988;70A:1538 –1551. 11. Field J, Majkowski RJ, Leslie IJ. Poor results of Darrach’s procedure after wrist injuries. J Bone Joint Surg 1993;75B: 53–57. 12. Sotereanos DG, Leit ME. A modified Darrach procedure for treatment of the painful distal radioulnar joint. Clin Orthop 1996;325:140 –147. 13. Breen TF, Jupiter JB. Extensor carpi ulnaris and flexor carpi ulnaris tenodesis of the unstable distal ulna. J Hand Surg 1989;14A:612– 617. 14. Hui FC, Linscheid RL. Ulnotriquetral augmentation tenodesis: a reconstructive procedure for dorsal subluxation of the distal radioulnar joint. J Hand Surg 1982;7:230 –236.
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15. Scheker LR, Belliappa PP, Acosta R, German DS. Reconstruction of the dorsal ligament of the triangular fibrocartilage complex. J Hand Surg 1994;19B:310 –318. 16. Bowers WH. Distal radioulnar joint arthroplasty: the hemiresection-interposition technique. J Hand Surg 1985;10A: 169 –178. 17. Watson HK, Gabuzda GM. Matched distal ulna resection for posttraumatic disorders of the distal radioulnar joint. J Hand Surg 1992;17A:724 –730. 18. Sauve L, Kapandji M. Nouvelle technique des traitement chirurgical des luxations redidivantes isolees de l’extremite intericubitus. J Chir 1936;47:589 –594. 19. Hagert CG. Distal radius fracture and the distal radioulnar joint—anatomical considerations. Handchir Mikrochir Plast Chir 1994;26:22–26. 20. Ishii S, Palmer AK, Werner FW, Short WH, Fortino MD. Pressure distribution in the distal radioulnar joint. J Hand Surg 1998;23A:909 –913. 21. Palmer AK, Werner FW. Biomechanics of the distal radioulnar joint. Clin Orthop 1984;187:26 –35. 22. Sauerbier M, Fujita M, Hahn ME, Neale PG, Berger RA. The dynamic radioulnar convergence of the Darrach procedure and the ulnar head hemiresection interposition arthroplasty: a biomechanical study. J Hand Surg 2002; 27B:307–316. 23. Masaoka S, Longsworth SH, Werner FW, Short WH, Green JK. Biomechanical analysis of two ulnar head prostheses. J Hand Surg 2002;27A:845– 853. 24. Sauerbier M, Hahn ME, Fujita M, Neale PG, Berglund LJ, Berger RA. Analysis of dynamic distal radioulnar convergence after ulnar head resection and endoprosthesis implantation. J Hand Surg 2002;27A:425– 434. 25. Kapandji AI. Distal radio-ulnar prosthesis [French]. Ann Chir Main Memb Super 1992;11:320 –332. 26. van Schoonhoven J, Fernandez DL, Bowers WH, Herbert TJ. Salvage of failed resection arthroplasties of the distal radioulnar joint using a new ulnar head prosthesis. J Hand Surg 2000;25A:438 – 446. 27. Swanson AB. Implant arthroplasty for disabilities of the distal radioulnar joint. Use of a silicone rubber capping implant following resection of the ulnar head. Orthop Clin North Am 1973;4:373–382. 28. Stanley D, Herbert TJ. The Swanson ulnar head prosthesis for post-traumatic disorders of the distal radio-ulnar joint. J Hand Surg 1992;17B:682– 688. 29. Johnson RK, Shrewsbury MM. The pronator quadratus in motions and in stabilization of the radius and ulna at the distal radioulnar joint. J Hand Surg 1976;1:205–209. 30. Scheker LR, Babb BA, Killion PE. Distal ulnar prosthetic replacement. Orthop Clin North Am 2001;32:365–376. 31. Bradway JK, Amadio PC, Cooney WP. Open reduction and internal fixation of displaced, comminuted intra-articular fractures of the distal end of the radius. J Bone Joint Surg 1989;71A:839 – 847. 32. Berger RA, Cooney WP III. Use of an ulnar head endoprosthesis for treatment of an unstable distal ulnar resection: review of mechanics, indications, and surgical technique. Hand Clin 2003;21:603– 620. 33. Cooney WP, Bussey R, Dobyns JH, Linscheid RL. Difficult wrist fractures. Perilunate fracture-dislocations of the wrist. Clin Orthop 1987;214:137–147.
Purpose: To report our experience using a distal ulnar head endoprosthesis to treat painful disorders of the distal radioulnar joint (DRUJ) secondary to (1) instability and (2) arthrosis. Methods: Our experience with over 2 years of follow-up study consists of 19 wrists (17 patients). All patients presented complaining of pain and functional disability of the upper limb due to convergence instability or arthrosis of the DRUJ. The patients were studied prospectively. Thirteen patients had a total of 37 previous wrist or DRUJ surgical procedures. Standardized preoperative and postoperative assessments included a patient-reported pain score, a functional satisfaction score, forearm range of motion, grip strength as a percentage of that of the opposite limb, and clinical and radiographic examinations. The Mayo Wrist Score was calculated before surgery and at the last follow-up period. Results: Overall, pain scores decreased 50%, and functional satisfaction scores improved 3-fold. Average grip strength improved by 4 kg, or 16% from preoperative measurements. Forearm rotation was unchanged. All wrists were clinically stable on the latest follow-up examination. Two failures occurred early, at 7 and 14 months. Currently, all prostheses remain clinically and radiographically stable. Conclusions: Implant arthroplasty of the distal ulna combined with an adequate soft-tissue repair is recommended to improve pain, function, and strength of the wrist and forearm. Prosthetic replacement of the distal ulna restored stability to the DRUJ in patients with partial or complete excision of the ulnar head or DRUJ arthrosis and corrected radioulnar impingement. Incidences of complications or revision surgery to date have been low. Larger clinical and radiographic assessments will be needed to determine the long-term success of distal ulna prosthetic replacement. (J Hand Surg 2007;32A:177–189. Copyright © 2007 by the American Society for Surgery of the Hand.) Type of study/level of evidence: Therapeutic IV. Key words: Arthroplasty, distal radioulnar joint, ulnar head prosthesis, distal ulnar resection.
n intact distal radial ulnar joint (DRUJ) is critical to stability and load transmission in the wrist and forearm. Chronic instability and arthritic change at the DRUJ can lead to pain, decreased forearm rotation, diminished grip strength, and inability to perform gainful employment activities.1 Resection of the distal ulna has been used to treat these problems, and favorable results have been reported.2,3 It is increasingly recognized, however, that removal of the ulnar head has the potential to destabilize the forearm as well as the wrist. Complications after the distal ulnar resection (Darrach pro-
A
cedure) are not uncommon, especially mechanical impingement of the distal ulna against the radius.4 –9 In most patients this instability is associated with pain on stress loading of the upper limb, weakening of grip, loss of forearm rotation, and diminished lifting capacity.10 –12 Functional disability after distal ulnar resection can be considerable, and often the resulting symptoms can be worse than if surgery had not been performed at all.5,6 Patients who have painful instability after resection arthroplasty of the distal ulna present a difficult challenge. Several reconstructive procedures, includThe Journal of Hand Surgery
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ing tenodesis,13,14 a tethering procedure using tendon graft,15 partial head resection with or without softtissue interposition,16,17 and fusion of the distal radius and ulna with creation of a proximal pseudarthrosis,18 have been developed as alternatives or supplements to the Darrach procedure in an attempt to prevent complications associated with ulnar instability. These procedures, however, tend to be unpredictable in relieving pain, preventing radioulnar impingement, and providing a stable forearm. Furthermore, some of these techniques can cause the very same instability that they were designed to avoid.5,9 The intact DRUJ resists both tensile and compression loads in the wrist and forearm10 –21 and helps maintain a correct axis of rotation for the forearm.21–23 Resection of the ulnar head has been shown to cause a 3-dimensional instability, especially in the axial and transverse planes.22–24 To restore stability to the upper limb after resection arthroplasty of the DRUJ, we believe that it is necessary to (1) insert a mechanical spacer that is able to realign the forearm bones and resist pressure loads applied to the ulna and (2) reconstruct the soft-tissue attachments between the radius, ulna, and carpus to resist tensile forces in the forearm and wrist. We report the outcomes of a series of 17 consecutive patients (N ⫽ 19 wrists) treated at our institution who had metallic implant arthroplasty of the distal ulna using an endoprosthesis (uHead endoprosthesis, Small Bone Innovations, New York, NY). Implant arthroplasty was performed (1) as a salvage procedure for painful DRUJ instability after distal ulnar resection arthroplasty and (2) as a primary procedure for painful DRUJ arthrosis. Institutional review board approval was obtained to study this patient cohort.
Materials and Methods Prosthetic Design The ulnar head prosthesis that we used (uHead endoprosthesis, Small Bone Innovations) is a modular endoprosthesis that consists of a metal stem with a shaft that can be press-fit or cemented into the intramedullary canal of the distal ulna (Fig. 1). A metal semispheric ulnar head of cobalt– chrome alloy is connected to an intramedullary stem of cobalt– chrome alloy with a commercially pure titanium sprayed finish through a tight-fit Morse-taper junction. There are 2 stem-neck designs: an extended collar for revision of previous distal ulna complete resection and a normal collar for primary procedures
Figure 1. Ulnar head prosthesis. (A) The prosthesis has an intramedullary component (left) and an articulating head (right). (B) There are 2 stem options. Top: Extended collar, which is used in revision procedures such as previous distal ulna resection. Bottom: Normal stem and collar, which can be used in primary procedures calling for ulna head removal and also for the revision of failed partial distal ulna head excisions.
calling for ulnar head excision and for revision of failed distal ulnar head resection procedures (Fig. 1B). The head has a provision for fixation of the triangular fibrocartilage complex (TFCC) and extensor carpi ulnaris (ECU) subsheath to the device by way of sutures, which we believe is advantageous for initial soft-tissue stabilization (Fig. 2). To ensure adequate length correction after previous surgery, differently sized ulnar head components and extended collars are available to compensate for shortening of the ulna after ulnar head resection. Surgical Technique The surgical technique uses a dorsal skin incision centered over the DRUJ in line with the fourth metacarpal. The full technique is described in detail in a separate publication.25 Briefly, a midline ulnar (medial) incision can be used primarily or after a previous distal ulna procedure. The extensor retinaculum is identified and divided through the fifth extensor compartment. A dorsoulnar-based capsuloretinacular flap is raised at the level of the fourth extensor compartment and dissected carefully in an ulnar direction to the base of the sixth compartment. The ECU subsheath and ECU tendon are left in place and elevated subperiosteally in a radial-to-ulnar direction as a capsular subperiosteal flap. The TFCC is left in continuity with the ECU subsheath as they are carefully freed from the distal ulna. With guidance from
Willis, Berger, and Cooney / Prosthetic Replacement, Distal Ulna
Figure 2. (A) The ulnar head prosthesis provides for fixation of the soft-tissue supports of the DRUJ. Sutures from ECU subsheath and TFCC to ulnar head are shown. (B) Detailed ECU and TFCC repair with the articulated ulnar head and soft-tissue attachment. © Mayo Foundation.
preoperative templated x-rays and an intraoperative resection guide that is used to determine the correct length of the implant, an osteotomy is made through the distal third of the ulna. After removal of the ulnar head, the sigmoid notch is inspected for incongruity or bone spurs and is contoured appropriately with a burr if needed. If there is a peripheral TFC tear, suture repair with a 3-0 nonabsorbable suture is performed, and the suture end is attached to the ulnar side of the prosthesis ulnar head at a later stage in the procedure (Fig. 2). For preparation of prosthesis insertion, the intramedullary canal of the distal ulna is reamed with increased-diameter broaches to the appropriately sized implant stem. Stem size is determined from radiolucent templates placed over the distal ulna, with magnification controlled. A trial prosthesis is used to check the size of the head and stem that restores optimum length and stability. Biplanar imaging is used to match ulna length and fit with the sigmoid fossa of the distal radius. Ulnaneutral or slight ulnaminus variance is recommended with respect to the length of the distal radius and ulna
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head replacement. Care is taken to match the ulna head size by templating to the opposite unaffected ulna head when possible. Depending on bone quality, the prosthesis is either press-fit or cemented. Cementing the prosthesis is recommended in case of previous wrist fusion or osteoporotic bone. Soft-tissue repair is an important component in the surgical procedure to provide temporary stabilization of the prosthesis within the DRUJ. The triangular fibrocartilage (TFC), ECU subsheath, and ulnar capsule are secured to the metallic ulna head directly with 2-0 or 3-0 nonabsorbable sutures to promote formation of a stable soft-tissue envelope about the prosthesis (Fig. 2). The ECU sheath is sutured proximal to the sutures for the TFC. The position of the ulna head is located on the Morse-taper of the stem to place the ulna head holes dorsal medial (Fig. 3). The soft-tissue repair to the ulna head is performed before connecting the ulna head to the stem of the prosthesis. In addition, an extended collar of variable sizes can be used to restore ulnar length after a previous complete distal ulna resection (Fig. 1B). Soft-tissue closure using the capsuloretinacular flap is performed with reattachment of the soft-tissue flap to the dorsal rim of the sigmoid fossa of the distal radius. Sufficient tension is used to ensure stability of the DRUJ. The repair is performed by direct suture, with drill holes dorsally on the sigmoid fossa or with suture anchors. Stability is augmented as required with local tissue and in some cases with a strip of the flexor carpi ulnaris (FCU) tendon that is left attached distally to the pisiform and brought across the waist of the ulnar head prosthesis where it is attached by suture anchor to the distal radius.
Figure 3. Repair of the soft tissues (ECU subsheath and TFC) to the ulna head prosthesis. The ECU tendon and subsheath are shown with a suture in the ECU tendon (held by hemostat) secured to dorsal-ulnar aspect of the ulna head prosthesis. © Mayo Foundation.
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Table I. Preoperative Clinical and Radiographic Characteristics of Study Population: Ulnar Head Arthroplasty Gender
Age, y
1
F
62
Repetitive microtrauma (overuse)
None
2
F
32
Trauma (DRUJ dislocation)
Sauve-Kapandji
3
M
53
Trauma (SLAC wrist)
4
F
39
Trauma (LT dissociation)
Partial wrist fusion, complete wrist fusion, Darrach, revision Darrach, interposition arthroplasty Partial wrist fusion (n ⫽ 3)
5
F
43
Trauma (distal radius malunion)
6
M
72
7
M
8
Original DRUJ Injury
Prior Surgery
Complaint
Physical Examination
Imaging
Ulnar-sided wrist pain, esp with forearm rotation Ulnar-sided wrist pain, esp with forearm rotation Ulnar-sided wrist pain, ulnar stump instability
DRUJ tenderness, crepitance, dorsal ulnar prominence
X-ray: DRUJ sclerosis, osteophytes
Piano-key sign, RU impingement pain (compression, grip)
Ulnar-sided wrist pain, grip weakness
DRUJ tenderness, pain with compression
Berger-Adams stabilization procedure
Ulnar-sided wrist pain, forearm motion loss
Rheumatoid arthritis
Wrist arthroscopy, AIN/PIN neurectomy
Ulnar-sided wrist pain, rheumatoid arthritis
DRUJ tenderness, piano-key sign, pain with compression, dorsal ulnar prominence DRUJ tenderness, crepitance
X-ray: Sauve-Kapandji pseudarthrosis; CT: radioulnar convergence X-ray: wrist arthrodesis, resection distal ulna; stress x-ray: radioulnar convergence X-ray: partial wrist arthrodesis, positive ulnar variance X-ray: DR malunion, DRUJ osteophytes
70
Trauma (DRUJ dislocation)
Darrach
Ulnar-sided wrist pain, grip weakness
Piano-key sign, RU impingement pain (compression, grip)
F
45
Repetitive microtrauma (overuse)
Ulnar-sided wrist pain
DRUJ tenderness, crepitance, piano-key sign
9
M
67
Psoriatic arthritis
Ulnar shortening, HIT arthroplasty; median nerve harvest for tendon interposition None
Ulnar-sided wrist pain, psoriatic arthritis
DRUJ tenderness, pain with compression
10
F
45
Trauma (distal radius fracture)
None
Ulnar-sided wrist pain, esp with forearm rotation
11
M
49
Trauma (fall on wrist)
Darrach
12
F
34
Repetitive microtrauma (overuse)
Darrach, revision Darrach, soft-tissue stabilization (n ⫽ 3), ulnar lengthening, interposition arthroplasty
Ulnar-sided wrist pain, ulnar stump instability Ulnar-sided wrist pain, ulnar stump instability
DRUJ tenderness, crepitance, piano-key sign, RU impingement pain (compression, grip) Piano-key sign, RU impingement pain (compression, grip)
Piano-key sign, RU impingement pain (compression, grip)
Piano-key sign, RU impingement pain (compression, grip)
X-ray: pancarpal DJD; MRI: eburnation ulnar head, sigmoid notch X-ray: radiocarpal DJD, resection distal ulna, radioulnar convergence X-ray: resection distal ulna; stress x-ray: radioulnar convergence X-ray: radiocarpal, DRUJ sclerosis; CT: dorsal subluxation ulnar head X-ray: DRUJ diastasis, sclerosis, subchondral cysts X-ray: partial resection distal ulna; stress x-ray: radioulnar convergence X-ray: resection distal ulna; stress x-ray: radioulnar convergence
The Journal of Hand Surgery / Vol. 32A No. 2 February 2007
Pt. No.
Table I. Continued Gender
Age, y
13
F
50
Trauma (chronic Essex-Lopreste)
14
M
35
14
M
15
Original DRUJ Injury
Prior Surgery
Complaint
Physical Examination
Imaging
Ulnar-sided wrist pain, esp with forearm rotation
DRUJ tenderness, crepitance, piano-key sign, pain with compression
X-ray: positive ulnar variance, ulnar head subchondral cysts
Rheumatoid arthritis
Ulnar shortening, soft-tissue stabilization, revision ulnar shortening, interposition arthroplasty None
36
Rheumatoid arthritis
AIN/PIN neurectomy
M
75
Repetitive microtrauma (overuse)
None
15
M
75
Repetitive microtrauma (overuse)
None
16
F
48
Trauma (SLAC wrist)
Complete wrist fusion, PIN neurectomy, soft-tissue stabilization
Ulnar-sided wrist pain, rheumatoid arthritis Ulnar-sided wrist pain, rheumatoid arthritis Ulnar-sided wrist pain, esp with forearm rotation Ulnar-sided wrist pain, esp with forearm rotation Ulnar-sided wrist pain, esp with forearm rotation
DRUJ tenderness, pain with compression DRUJ tenderness, pain with compression DRUJ tenderness, pain with compression, dorsal ulnar prominence DRUJ tenderness, pain with compression, dorsal ulnar prominence DRUJ tenderness, crepitance, piano-key sign, pain with compression
17
M
39
Trauma (fall on wrist)
Partial wrist fusion, ulnar styloidectomy
Ulnar-sided wrist pain
DRUJ tenderness, crepitance, pain with compression
X-ray: radiocarpal DJD, DRUJ dissociation X-ray: pancarpal DJD, DRUJ dissociation X-ray: radiocarpal, DRUJ sclerosis, positive ulnar variance X-ray: radiocarpal, DRUJ sclerosis, positive ulnar variance X-ray: wrist arthrodesis, dorsal subluxation ulnar head, DRUJ sclerosis; BS: increased signal at DRUJ X-ray: partial wrist fusion; DRUJ subluxation
AIN, anterior interosseous nerve; CT, computed tomography; DJD, degenerative joint disease; DR, dorsoradial; esp, especially; HIT, hemiresection interposition; LT, Lunotriquetal; MRI, magnetic resonance imaging; PIN, posterior interosseous nerve; pt, patient; RU, radioulnar.
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Stability of the DRUJ after the soft-tissue repair can be judged at surgery by stressing the DRUJ dorsal and palmarly and by assessing stability during forearm pronation and supination. Other soft-tissue augmentation beside the capsule alone or with the FCU tenodesis was performed in 1 patient for whom fascia lata was used to augment a deficient capsule. After capsule closure, the extensor retinaculum is closed over the capsule, restoring the normal anatomic position of the extensor tendons. After surgery, the forearm is immobilized in midrotation and held in a supportive long-arm splint or cast for 4 to 6 weeks, depending on assessment of DRUJ stability at the time of surgery. Usually 4 weeks after surgery the cast is removed and the patient is placed into a removal muenster-type splint that allows for elbow flexion– extension but controls forearm rotation. Active ranges of motion of the wrist and forearm are initiated between 4 and 6 weeks, depending on the soft-tissue repair and intraoperative stability of the arthroplasty. When the patient has achieved 45° of pronation and 45° of supination, the forearm support splint is discontinued and therapy is advanced as tolerated. At 8 weeks, therapy incorporates strengthening exercises, and the patient
is then allowed to gradually return to normal activities. Patient Series Nineteen ulnar head arthroplasties have been performed in 17 patients using the endoprosthesis (uHead endoprosthesis, Small Bone Innovations) (Table 1). The average follow-up period has been 32 months (range, 26 – 60 mo). There were 8 men and 9 women with an average age of 51 years (range, 32–75 y). The dominant extremity was involved in 8 cases. Seven patients were manual laborers by trade (Fig. 4), and 1 patient was receiving workers’ compensation related to the DRUJ injury. All patients presented with complaints of pain with activity using the affected limb and debilitating functional impairment. Indications for ulnar arthroplasty were distal ulnar instability (and/or radioulnar impingement) (Fig. 5) after resection of the ulnar head (6 wrists) or DRUJ arthrosis (11 wrists) and inflammatory arthritis (2 wrists). The original injury to the DRUJ was trauma related in 12 wrists, repetitive overuse with instability in 5 wrists; there was 1 patient with rheumatoid arthritis and 1 patient with psoriatic arthritis. Thirteen patients had a total of 37 previous surgeries
Figure 4. (A) A PA radiograph of a 50-year-old manual laborer with radiocarpal arthritis, ulnocarpal impaction, and painful motion at the DRUJ. (B) A PA close-up view and (C) full-length view of the wrist after radioscapholunate fusion combined with distal ulna resection and ulnar head replacement; surgical staples removed. Stable distal ulna with mild ulnocarpal impingement and slight resorption at ulna head–shaft junction secondary to stress shielding. (D) Lateral view of the wrist at 28 months. Patient has returned to work with absence of pain and 80% normal forearm rotation. © Mayo Foundation.
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Figure 5. Clinical case of radioulnar impingement with failed distal ulna resection. (A) A PA view the showing area of impingement (scalloping distal radius). (B) Lateral view with mild to moderate dorsal displacement of the distal ulna. (C) Postoperative PA view in plastic cast of the ulnar head replacement articulating joint inferior to the sigmoid notch. After 3 years, (D) PA and (E) lateral views of the right wrist shows a stable DRUJ without impingement. There is mild ulna head–shaft bone resorption with no evidence of implant loosening. © Mayo Foundation.
related to the distal ulna and DRUJ, with an average of 2.8 (range, 1–5) surgeries per patient. Previous surgery included 6 Darrach resections,2 1 SauveKapandji procedure,18 1 Bowers hemiresection interposition procedure,16 6 soft-tissue stabilizations,6 3 interpositional arthroplasties of the DRUJ with either the pronator quadratus muscle29 or allograft fascia lata, 3 ulnar-shortening procedures, and 1 ulnarlengthening procedure. There were 5 partial and 2 complete wrist fusions. In the 6 wrists with symptomatic distal ulnar instability, 4 were secondary to a previous Darrach procedure, 1 was secondary to a
previous Sauve-Kapandji procedure with proximal instability, and 1 was secondary to a previous Bower’s procedure. Subsequently, 2 patients had revision Darrach procedures, and 1 patient had had 3 previous soft-tissue stabilizations of the ulnar stump. Two patients had prior interpositional arthroplasty of the DRUJ with fascia lata allograft, and 1 patient had an ulnar-lengthening procedure in an attempt to relieve the painful instability resulting from the original procedure (all without improvement). All patients in this study were subject to standardized preoperative and postoperative assessments.
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Table 2. Verbal Analog Pain Scale Pain
Strength Value
No pain Pain with strenuous activity Pain with high activity Severe pain without activity
1 2 3 4
From van Schoonhoven et al.26
Pain was evaluated with a verbal analog pain scale ranging from 1 to 4 points, similar to that described by van Schoonhoven (Table 2)26: 4, patient was very satisfied with the function of the hand and arm; 3, patient was satisfied with the function of the hand and arm; 2, patient was somewhat satisfied with the function of the hand and arm and during the postoperative assessment rated it as only fair or improved compared with the preoperative status; and 1, patient was not satisfied with the function of the hand and arm and during the postoperative assessment rated it as the same or worse than before surgery. The Mayo Wrist Score (Table 3) applied to conditions affecting the DRUJ was applied to patients before and after surgery for pain, functional status (return to work), range of forearm rotation, and grip strength. A score of 90 to 100 was excellent; 80 to 89, good; 65 to 79, fair; and les than 65, poor. In the 2 bilateral cases, the scores for motion and grip were based on healthy age- and gender-matched controls. Forearm motion (rotation) was recorded as the degrees of pronation and supination from the neutral position. Grip strength was measured using a dynamometer (Jamar dynamometer; Preston, Cambridge, MA) and was recorded as a percentage of that of the opposite limb. Clinical examination included assessment of DRUJ tenderness by direct palpation, the presence of a positive piano-key sign indicating anterior–posterior instability of the ulna, the presence of radioulnar convergence impingement or DRUJ pain on manual compression testing, and DRUJ crepitus on forearm rotation. Forearm stability and DRUJ arthritis were also assessed radiographically by posteroanterior (PA) x-rays and a lateral x-ray in midforearm rotation. Before surgery, dorsal displacement of the ulna (as recorded on lateral x-rays from neutral alignment), proximal radioulnar impingement (as evidenced by scalloping of the radius on PA radiograph), and degenerative changes of the ulnar head or sigmoid notch (noted as loss of joint cartilage at the DRUJ) were recorded. After surgery, the latest radiographs were examined and recorded for signs of
recurrent instability (percentage of dorsal displacement of the ulna), loosening of the prosthetic stem (⬎2 mm of lucency around the prosthesis stem), or bony reactions within the sigmoid fossa or distal ulna. At the time of the initial procedure, 13 stems were press-fit and 6 were cemented. The cemented prostheses were used in cases of previous wrist fusions and in rheumatoid disease or osteoporotic bone. Three extended collars were required to compensate for previous excessive resection of the distal ulna. All 13 wrists with an intact ulnar head had degenerative wear of the ulnar head confirmed at the time of surgery. Seven wrists also had degenerative changes Table 3. Mayo Wrist Score Category Pain (25 points)
Functional status (25 points)
Score, Points 25 20 15 0 25 20 15 0
Range of motion (25 points)
25 15 10 5 0
None Mild, occasional Moderate, tolerable Severe or intolerable Returned to regular employment Restricted employment Able to work but unemployed Unable to work because of pain Percentage of normal 100
25
75–99 50–74 25–49 0–24 Flexion–extension arc,° (injured hand only) ⱖ120 91–119 61–90 31–60 ⱕ30 % of normal 100
15 10 5 0
75–99 50–74 25–49 0–24
Excellent Good Fair Poor
90–100 80–89 65–79 ⬍65
25 15 10 5 0 Grip strength (25 points)
Findings
Final Result
From Bradway JK et al,31 Berger and Cooney,32 and Cooney et al.33
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Table 4. Comparison of Preoperative and Postoperative Outcome Measures Mean (SD) Outcome
n
Pain Forearm supination Forearm pronation Forearm rotation arc Grip strength, % Mayo Wrist Score
19 18 18 18 15 19
Before Surgery 3.6 60.8 74.4 135.3 75 41
(0.5) (30.2) (14) (37.8) (29) (16)
Median (min, max)
After Surgery
Before Surgery
1.8 60 71.7 131.7 73 77
4 67.5 70 135 68 45
(1) (23.8) (15) (31.6) (21) (13)
(3, 4) (⫺10, 90) (55, 90) (60, 180) (33, 147) (15, 70)
After Surgery 2 72.5 75 145 83 75
(1, 4) (10, 80) (45, 90) (80, 170) (40, 108) (55, 95)
p ⬍.01* .90† .51† .65† .83† ⬍.01†
Paired t tests were used to compare the preoperative and postoperative values of grip strength and the forearm rotation measures. Because pain is distributed as an ordinal variable, it was compared with a (nonparametric) signed rank test. All statistical tests were 2-sided, and p values less than .05 were considered significant. *Signed rank test. †Paired t test.
present within the sigmoid notch. These degenerative changes were treated by smoothing and rounding off the sigmoid notch with a small acorn-shaped burr. Three wrists required additional soft-tissue reconstructions with Linscheid-Hui procedure.14 Stability, as judged clinically, was restored in all patients at the time of surgery, based on assessment of the dorsal– volar displacement in both forearm pronation and supination. Statistical Analysis To assess the significant differences between preoperative and postoperative outcomes in grip strength and forearm rotation, a paired t test was performed (Table 4). To measure pain differences, a nonparametric signed rank test was performed. All statistical tests were 2-sided, and p values less than .05 were considered significant. In addition, the preoperative and postoperative Mayo Wrist Scores were statistically assessed with a nonparametric t test.
Results Clinical Results Seventeen patients who had ulnar arthroplasty of the DRUJ in 19 wrists stated that they were improved after this procedure and would have the surgery performed again. Eighteen of 19 wrists reported having improved pain compared with the preoperative status. All patients had pain relief at rest; 5 patients had mild pain with activity, but this was improved from the preoperative pain level. Pain scores decreased from a preoperative mean level of 3.6 to a postoperative mean level of 1.8 (a 50% reduction in patient-reported pain scores). The improvement in pain was statistically significant (Table 4). The 1 patient who had persistent pain with activities had sigmoid notch arthrosis with degenerative changes
involving the entire ulnar head at the time of surgery. She also had had a previous wrist arthrodesis. Because her DRUJ pain did not improve, she subsequently was treated with a custom arthroplasty of the DRUJ (replacement of the sigmoid fossa with a polyethylene–metal resurfacing implant and standard distal ulna prosthesis). She had a successful outcome at 2 years after surgery. In this series of 19 wrists, hand and arm functional satisfaction scores improved from a preoperative mean level of 1.1 to a postoperative mean level of 3.3. This represents a 3-fold overall improvement in patient-reported satisfaction scores with upper-limb function. Only 1 patient was completely unsatisfied with the functional outcome of the ulnar head arthroplasty procedure (noted earlier). Two patients were only partially satisfied. Of these, one has painful forearm rotation with extended use and moderate grip weakness. The other patient has global wrist pain and weakness not clearly related to the DRUJ, which remains clinically and radiographically stable. Grip strength improved from a preoperative mean of 67% of the opposite limb to a postoperative mean of 83%. After surgery, there was an average improvement in grip strength of 4 kg compared with preoperative values. The change in grip was statistically significant based on the strength of the opposite limb (Table 4). Forearm arc of motion was unchanged. Supination had a preoperative mean of 60° compared with a postoperative average of 60° and median of 67° to 72°. Pronation had a preoperative average of 70° and a postoperative average of 75°. Changes in forearm rotation were not statistically significant. The Mayo Wrist Score improved from a preoperative mean of 40 (range, 15–70) to a postoperative mean of 77
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Table 5. Postoperative Wrist Scores and Follow-Up Periods
Pt No.
Preop Wrist Score
Postop Wrist Score
Overall Delta Outcome
1 2
40 40
75 70
35 30
3 4
20 45
70 55
35 10
5 6 7 8 9 10 11 12 13 14
15 55 45 35 45 65 40 15 15 70
80 95 85 75 75 95 95 75 65 80
65 40 40 40 30 30 45 65 50 10
None Ulna diaphysis; fracture healed Fair None Poor Ulnar neuropathy persistent Good None Excellent None Good None Good Ulnar neuropathy resolved Good None Excellent None Excellent None Fair None Fair None Good Unstable painful DRUJ
15 15 16
50 45 30
85 80 75
35 35 55
Good Good Good
None None Loosening ⫹ arthritis DRUJ
17
50
90
40
Good
Loosening
Complications
Good Fair
Revision Surgery
Length of Follow-Up Period, mo
None None
21 48
None None
72 16
None None None None None None None None None Free palmaris graft reconstruction None None Cemented distal ulna, custom sigmoid fossa Cemented distal ulna
12 36 24 (pt deceased) 16 (pt in prison) 16 45 37 15 36 41 18⫹⫹ ____? 24†
25†
Postop, postoperative; preop, preoperative; pt, patient. *Indicates result after revision surgery. †Indicates length of follow-up study after revision surgery.
(range, 55–95) (Table 5). Based on the Mayo Wrist Score there was a mean improvement of 35 points (range, 10 –55). The improvement in the Mayo Wrist Score was statistically significant (Table 4). No wrist lost points. Based on the Wrist score there were 4 excellent, 10 good, 4 fair, and 1 poor results (Table 5). On clinical examination, 17 wrists had tenderness localized over the DRUJ before surgery, but mild tenderness was present in only 2 wrists after surgery. A positive piano-key sign was present in 10 wrists before surgery, and radioulnar impingement was present in 6 wrists that had had previous distal ulnar resection procedures. After surgery, 1 wrist had clinical signs of mild dorsal ulna instability. Radioulnar impingement pain in 6 patients before surgery was completely corrected. Seven wrists had painful crepitus on forearm rotation during examination before surgery; 2 wrists had painless crepitance on forearm rotation after surgery. Eight of 13 wrists with DRUJ arthrosis before surgery had a markedly positive radioulna compression test. Only 1 wrist with sigmoid notch arthrosis (noted earlier) was had a positive compression test result after surgery.
Imaging Results Preoperative imaging with standard lateral radiographs showed gross distal ulnar instability in 5 of the 6 wrists with previous ulnar head excision. Radioulnar impingement with scalloping of the radius was also noted (Fig. 5). One patient with a previous Bowers procedure16 had convergence instability only on dynamic stress imaging. Ten of 12 wrists with symptoms of arthrosis of the intact DRUJ had clear arthritic changes on radiographic imaging before surgery. Nineteen of 19 wrists were radiographically stable at the latest postoperative assessments. Signs of remodeling of the sigmoid fossa were present around the metallic head. One patient had progressive degeneration of the sigmoid notch (mentioned earlier) and has had a revision surgical procedure. There was evidence of prosthetic loosening of the stem in 2 patients, both of whom had a successful revision with reinsertion of the prosthesis with bone cement. Five of 19 wrists had slight bone resorption (1–2 mm) beneath the collar of the prosthesis. This resorption, however, has stabilized
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and, at average 32 months of follow-up study, has not progressed. Complications Four patients had complications, 1 early and 3 late. There was 1 intraoperative nondisplaced fracture of the ulna in this series that occurred during canal preparation of the ulna diaphysis (early complication). This was related to impacting the broach rather than rasping with the broach. The fracture was stabilized with a 3.5-mm cortical screw proximal to the prosthesis. This patient has gone on to an otherwise uneventful recovery and is rated overall as an excellent outcome. Late complications include 1 patient with painful neuroma of the dorsal cutaneous branch of the ulnar nerve that has adversely affected her overall outcome. A second patient developed intermittent instability of the ulnar head prosthesis, which became symptomatic 5 months after surgery. This patient was determined later to have a clinical history of rheumatoid arthritis and, in retrospect, had a suboptimal soft-tissue envelope about the DRUJ. He had a concomitant wrist arthrodesis at the time of his ulnar head arthroplasty. Stability of the DRUJ was restored at revision surgery with a distally based strip of FCU tendon (Linscheid-Hui procedure).14 Currently, the prosthesis appears stable and the patient is doing well clinically. A third patient developed progressive degenerative changes of the sigmoid notch. He subsequently had a revision surgery to downsize the ulnar head and resurface the arthritic sigmoid notch. Two patients (mentioned earlier) had intramedullary stem loosening. The first patient developed proximal and distal osteolysis about a press-fit prosthetic stem with a windshield wiper configuration early in the postoperative course consistent with gross radiographic movement. Inadequate postoperative support and limb overuse with lifting appeared to be responsible factors. The prosthesis fixation was revised with bone cement. The second patient had a prior wrist fusion, which may have contributed to increased force across the DRUJ. Revision to a cemented stem was performed 14 months after surgery, and the prosthesis remains clinically and radiographically well fixed at 16 months after the revision procedure.
Discussion The concept of a replacement for the distal ulna is not new. Swanson27 developed a silicone ulnar head prosthesis as a means of alleviating complications after resection arthroplasty of the DRUJ and reported
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good clinical outcomes using his prosthesis as a mechanical spacer. Stanley and Herbert28 showed that use of a silicon ulnar head prosthesis (Silastic) combined with a soft-tissue repair could relieve symptoms and restore stability even in manual laborers. Although preliminary results were encouraging, complications using this prosthesis, including dislocation, prosthetic fracture, and silicone synovitis, have led investigators to conclude that an alternative prosthesis is needed. As a result, newly designed and improved DRUJ prostheses have been developed that appear to be more mechanically durable and biologically compatible, to anticipate long-term success with clinical use. A metallic endoprosthetic design helps recreate the bony and soft-tissue anatomy of the DRUJ (Small Bone Innovation). Cadaveric studies have shown that new-generation implants can restore near-normal biomechanics and kinematics of the upper limb compared with the intact state.23,24 Ceramic and metallic ulnar head endoprostheses have been introduced into the clinical setting as a salvage procedure for patients with painful instability after failed resection arthroplasty of the DRUJ, but they may have primary indications in painful DRUJ related to rheumatoid arthritis and posttraumatic arthritis. Although there are relatively few studies in the literature, preliminary outcomes25,26 with ulnar head implants have been encouraging. Although resection arthroplasty of the distal ulnar head and related procedures can be an effective treatment for painful disorders of the DRUJ,2– 4 these procedures alter inherent mechanical function and load transmission of the DRUJ and not infrequently can cause secondary wrist and forearm instability.5,6,8 The use of an ulnar head prostheses has been shown in cadaveric laboratory studies22–24 to prevent radioulnar convergence, maintain the kinematic relationship of the radius and ulna during forearm rotation, resist subluxating forces, and accept longitudinal load transmission in the wrist and forearm. Preliminary clinical reports using different ulnar head prostheses as a salvage procedure for painful disorders of the DRUJ have been encouraging. Van Schoonhoven et al26 reported on 23 patients with debilitating pain and instability of the DRUJ after resection arthroplasty who were treated with a metallic endoprosthesis and ceramic ulnar head combined with a simple soft-tissue repair as a salvage procedure. After a minimum 2-year follow-up period, the researchers reported significant improvements in pain scores, satisfaction scores, forearm
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motion, and grip strength. There were no prosthetic failures; however, 1 patient required removal of the prosthesis because of low-grade infection. Scheker et al30 reported on 23 patients with persistent pain and dysfunction after failed resection arthroplasty of the DRUJ or posttraumatic arthritis of the DRUJ after treatment with a custom-designed constrained ball and socket-type DRUJ prosthesis. They reported that all patients had complete pain relief and regained good lifting capacity at a mean of 15 months after the procedure. There were no significant complications or prosthetic failures reported in this series. Similarly, Kapandji25 developed a balland-socket–type prosthesis and has reported 2 cases of good clinical results. Laboratory studies24,25 using a dynamic cadaveric forearm simulator have shown nearly identical 3-dimensional displacements of the distal ulna using an endoprosthesis compared with the intact state. Furthermore, biomechanic loading studies have shown a statistically significant improvement in radioulnar convergence toward the intact state with placement of the ulnar head compared with resection of the ulnar head. Although the principal indication for metallic implant arthroplasty of the DRUJ is a failed resection of the distal ulna, we believe that there can be a primary procedure (hemiarthroplasty) in patients with arthritic change at the DRUJ. We believe at this time, based on this preliminary review, that ulnar head arthroplasty can provide good pain relief in patients with either radioulnar convergence instability or DRUJ arthrosis. Including the successful revisions, 90% of patients received a reasonable degree of pain relief and all but 1 patient were functionally satisfied with the outcomes of this procedure. There were no problems of DRUJ instability that we attribute to the soft-tissue repair (ECU subsheath and TFC) to the head of the prosthesis. We believe that this technique provides added stability compared with those ulnar head prostheses that rely on a capsule–retinacular flap alone.26 There are limitations to this study. Most of our patients had several previous surgical interventions to treat a multitude of problems in the affected extremity. This study limited postoperative assessment to the DRUJ and may explain why the grip strength improved only 16% from preoperative measurements and did not reach the strength of the uninjured extremity. Similarly, improvement in rotational motion of the forearm did not occur but was maintained after ulnar head replacement. Patients with previous Darrach resection, for example, had pain and instability
but had only slight loss of forearm rotation. The ulnar head prosthesis was designed to improve stability and decrease pain and in patients with previous Darrach procedures; improvement in motion was not an expected goal. With respect to outcome, the Mayo Wrist Score showed an improvement of 40 points between the preoperative and postoperative assessments. Although not a validated score such as the Disabilities of the Arm, Shoulder, and Hand questionnaire or Patient-Related Wrist Evaluation, the change in the Mayo Wrist Score represents a statistically significant improvement in physician-observed and -measured wrist function. Further studies with such patient-related information would provide more support for the clinical effectiveness of prosthetic replacement of the distal ulna. Concern has been raised about the potential for compression pressure effects and progressive degeneration of the metallic ulnar head on the sigmoid notch. To date, we have not found this to be the case. Minor arthritic changes or structural alterations in the sigmoid notch have not resulted in poor clinical outcomes in the patients in this series. One patient of the 19, however, did not improve and has had a custom resurfacing arthroplasty of the sigmoid fossa. Radiographically, the sigmoid notch appears to adapt and remodels to the contour and forces imparted by the ulnar head, a finding seen by others. Van Schoonhoven et al,26 for example, using a ceramic ulnar head, found that sigmoid notch remodeling and progressive erosion and cyst formation at the sigmoid notch occurred in only 1 patient. Clinically, ulnar head replacement produced adequate pain relief and restoration of function in this patient population, even in those patients in whom the sigmoid fossa required surgical remodeling with a burr to correct deformity or to allow adequate seating of the prosthetic ulnar head. Our preliminary results show that distal ulna prosthetic replacement combined with adequate soft-tissue repair can reliably restore stability to the DRUJ. The metallic ulnar head has been designed with suture holes that allow for temporary fixation of the TFCC and ECU subsheath to promote anatomic positioning of a soft-tissue sleeve about the prosthesis. This repair of the TFCC and ECU subsheath to the prosthesis—although temporary—is an important part of the soft-tissue procedure. In addition, it is important during the surgical procedure to assess the soft-tissue stabilization of the prosthesis by the retaining capsule and, if necessary, to add soft-tissue
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support with a strip of the FCU or autograft tendon.13,14 Longer follow-up periods and more extended clinical use by multiple hand surgeons is required to determine the long-term value of prosthetic replacement of the distal ulna. Received for publication October 5, 2005; accepted in revised form December 6, 2006. Drs. R.A. Berger and Dr. W.P. Cooney received benefits from Small Bone Innovations (SBI), New York. Dr. W.P. Cooney has received commercial research grants from SBI and serves as a consultant. Corresponding author: William P. Cooney, MD, Mayo Clinic, 200 First St, SW, Department of Orthopedic Surgery, Rochester, MN 55902; e-mail: [email protected]. Copyright © 2007 by the American Society for Surgery of the Hand 0363-5023/07/32A02-0007$32.00/0 doi:10.1016/j.jhsa.2006.12.004
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