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Elbow lengthening after total prosthetic arthroplasty: Observations and clinical implications
Elbow lengthening after total prosthetic arthroplasty: Observations and clinical implications N. Blewitt, FRCS, and J. Pooley, MD, FRCS,
Newcastle Upon Tyne, United Kingdom We have carried out a radiologic study to determine the effect on limb length of inserting the components of a total elbow [oin! replacement arthroplasty. The preoperative and postoperative radiographs of 27 consecutive patients undergoing total elbow ioint replacement arthroplasty with the Kudo prosthesis were studied. In all cases lengthening across the elbow was found. Both ulnar and humeral lengthening were observed. A mean length increase of 8.6 mm (range 2 to 77 mm) was recorded. Ulnar lengthening contributed to overall lengthening by a significantly greater amount than humeral lengthening . We correlated the degree of lengthening observed with clinical measurements in this series of patients but found no significant differences. Operative maneuvers are suggested to accommodate this length increase, to achieve soft-tissue balance, and to avoid potential complications such as ulnar neuropathy and ;oint instability. (J SHOULDER ELBOW SURG 7994;3:200-6)
The development of elbow prostheses suitable for general use began in the early 1970s when both fully constrained (linked) and semiconstrained (unlinked) implants were inserted and fixed with cement.' Examples include the Coonrad and the Triaxial prostheses.' Further study revealed that by imitating normal elbow kinematics and using less constrained implants, better results could be onticipoted." Such prostheses as the Souter/Strcthclyde," Capitellocondylar/ and the Kudo implcntsv" have confirmed this potential. At present the most common indication for total elbow joint replacement arthroplasty (TEJR) is rheumatoid disease. This disease affects the synovial joints by inducing inflammation and joint destruction with consequent painful loss of function. Joint destruction results from both bony erosion and From the University Deportment of Orthopaedics, Newcastle Upon Tyne. Reprint requests: N . BlewiH, FRCS, University Deportment of Orthopaedics, Newcastle Upon Tyne NEl 4LP, United Kingdom . Copyright © 1994 by Journal of Shoulder and Elbow Surgery Boord of Trustees. 1058-2746/94/$3.00 + 0 32/1/55146
200
periarticular soft-tissue inflammation with varying degrees of fibrosis. The overall effect is not only joint incongruity and painful limitation of movement but inevitably also a degree of pathologic shortening across the joint. We have observed lengthening across the joint after TEJR using the Kud0 6 • 7 unconstrained resurfacing prosthesis and report the clinical effect of lengthening on the patients studied.
MATERIAL AND METHODS Patients undergoing TEJR in our unit are studied prospectively. Preoperative recording of functional impairment and range of movement is entered onto standardized form, and both subjective and objective measurements are allocated scores (Table I). Subjective assessment includes the evaluation of function, pain, and analgesic requirements. Function is determined by ease or difficulty in performing certain basic act ivities such as feeding, washing, or dressing . Pain is measured with a visual analogue scale (15 for no pain, 0 for worst pain imaginable), and analgesia requirement is scored according to the presence of nocturnal pain and the required amounts and frequency of pain-relieving
J. Shoulder Elbow Surg. Volume 3, Number 4
Blewitt and Pooley
201
Figure 1 Rheumatoid arthritis is an erosive arthropathy resulting in joint destruction and pathologic joint shortening.
medication (low score for high frequency). Objective recordings include scores for the arc of motion and degree of fixed flexion . Muscle power is measured with the Medical Research Council (MRC) grading scale with a score of 5 allocated for normal motor power and 0 to indicate no active muscle contraction. Elbow stcbility is assessed by anteroposterior drawer testing and varus-valgus stressing. These clinical measurements were made both before surgery and 6 months after surgery in a consecutive series of 27 patients with rheumatoid arthritis in whom a Kudo TEJR was inserted . The shape of the components of the Kudo TEJR permits in addition to flexion and extension a degree of varus-valgus tilting and consequently rotation between humeral and ulnar components. This prosthesis therefore permits both hinging movement at the elbow and ulnar obduction and adduction, which take place during normal forearm pronation and supinotion.t ln this series the humeral component was inserted cementfree, and the ulnar component was cemented. After insertion of the components the wound was closed in layers with particular attention being directed to obtaining proper soft-tissue
Table Subjective and objective scores were obtained prospectively allowing comparison between preoperative and postoperative clinical scores Score (maximum) Subject ive Function Pain Analgesia requirement Subtotal Objective Range of motion Strength Stability Subtotal Overall total
36 15 ~
66
31 15 ~ ~ 118
balance, made possible by a wide surgical exposure. The anconeus muscle and its overlying fascia were repaired as a double layer to rein force this closure. After surgery the arm was rested in a lightweight splint for 3 to 5 days, and active physiotherapy was commenced within the limits of postoperative discomfort. The radiographs of these patients were as-
202
Blewitt and Pooley
J. Shoulder Elbow Surg. July/August 1994
Figure 2 Total joint replacement arthroplasty results in lengthening across elbow joint.
,\
A'
B'
R
Figure 3 Humeral lengthening is calculated by subtracting postoperative humeral length A-A' from preoperative humeral length A-A' , Ulnar lengthening is calculated by subtra cting postoperative ulnar length B-B' from preoperative ulnar length B-B' .
sessed before (Figure 1) and after (Figure 2) total elbow replacement. All the elbows were graded according to Larsen's clcssificotion" and were found to be either grade four or five. To determine whether lengthening had occurred across the joint as a result of the implantatian of the prosthetic components, ulnar and humeral lengths were measured on the preoperative and then on the postoperative radiographs (Figure 3). These measurements were recorded by a single observer. To ensure that
no error had been introduced as a result of magnification, the ulnar diaphyseal diameter was measured at a point 5 cm distal to the tip of the olecranon on both the preoperative and postoperative radiographs . In all cases it was confirmed that these two measurements were identical. The ulnar length was determined by measuring the distance of a perpendicular line drawn from the subcutaneous border of the ulnar to the estimated center of rotation of the elbow as judged on the lateral radiograph (ear-
J. Shoulder Elbow Surg. Volume 3, Number 4
Blewitt and Pooley
203
20
.
. . 15 •
. E
.s
.
----
10 '
:
J:.
e;,
UlNA
C
•
...J
Z
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2
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4
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e
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10 11 12 13 14 15 1& 17 18 1; 20 21 22 23 24 25 28 27 en. Number
Figure 4 Lengthening after tota l elbow replacement. Lengthening was observed to occur in all cases studied . Ulnar lengthening co ntributed significantly more to overall lengthening tha n did hume ral lengthen ing .
lier studies in this department had verified this method of estimation by measuring reproducibility and interobserver error) . Any increase in ulnar length was then calculated by subtracting the length measured on the postoperative radiograph. The humeral length was measured by drawing a perpendicular line passing through the center of rotation of the elbow to a reference point on the lower humerus readily identifiable on the preoperative and postoperative radiographs. The cortex of the supracondylar ridge provided a convenient landmark in most cases; however, other points were also used providing that they could be confidently identified on both the preaperative and postoperative radiographs . The postoperative reference value was then subtracted from the preoperative value to determine absolute humeral lengthening (Figure 3). Overall joint lengthening after TEJR was then calculated for each case as the sum of the value obtained for ulnar lengthening and the value obtained for humeral lengthening.
RESULTS All the elbows in this series were lengthened as result of TEJR. The overall results are presented in Figure 4. The mean overall length-
ening was found to be 8.6 mm (ronqe 2 to 17 mm). This mean lengthening was not contributed to equally by ulnar and humeral components. The mean ulnar lengthening was 6.6 mm (range 1 to 14 mm), and the mean value for humeral lengthening was 2.0 mm (range 2 to 9 mm). Analysis of these findings with the t test for matched data pairs identified a highly significant difference between ulnar and humeral lengthening. The "t value" was 4.9, which is greater than the critical tvalue of 3.43 required to achieve a significance level for p = 0.001. Clinical relevance. Having identified a mean lengthening across the elbow of 8.6 mm after TEJR in this series , we consulted the prospective clinical data obtained from these patients. We divided these patients into two groups, one group in whom the total measured lengthening was found to be greater than 9 mm and another group in whom the lengthening was found to be less than 9 mm. Before surgery we found no difference in either the subjective or objective scores between these two groups. These clinical scores together with those scores recorded 6 months after surgery are shown in Figures 5 and 6. It can be seen that there was no significant difference between the postoperative scores, either. There was, however, a
204 Blewitt and Pooley
J. Shoulder Elbow Surg. July/ August 1994
3S
30
2S
20 •
!
0
u
en
1S
--J
mean<9mm
~ :~n>9mm
,,--(
I 1
10
I
I
S~
I
o. Function
Analgesia
Pain
ROM
Stabtlit y
Strength
Figure 5 Preoperative clinical scores. There was na d ifference in preoperative clinical scores observed between two g roups . 3S
30
2S
20
I mea;";:~ ] ,,-,
!
0
u
I
Ul
..,
1S j
mean>9mm
r I I I
10
S
o· Fund,on
Pain
AnalgeSia
ROM
Strength
Stabtlity
Figure 6 Postoperative clinical scores . Comparing pos toperative clinical scores of group lengthened less than 9 mm w ith group lengthened more than 9 mm, no statistically sign ificant difference was noted. Range-of -mo tion scores tended to be better in the group lengthened by more than 9mm.
higher mean score for postoperative range of movement in the group with a measured length increase of more than 9 rnrn: this difference was found not to be statistically significont with the Wilcoxon rank sum test for unpaired data.
DISCUSSION Rheumatoid arthritis is an erosive inflammatory arthropathy manifested in the elbow as in other joints by bone destruction and soft-tissue changes. Articular cartilage is lost and under-
Blewitt and Pooley
J. Shoulder Elbow Surg. Volume 3, Number 4
lying bone is eroded. Periarticular soft tissue becomes inflamed, and later fibrosis and scarring develop. The net result is not only joint destruction with painful functional impairment but also a change in limb geometry as pathologic shortening across the joint inevitably occurs. 1 This shortening begins with loss of articular cartilage and is accentuated by underlying bony eros ion, and progression occurs associated with fibrotic contraction of inflamed periarticular soft tissues. This progression ultimately results in the ankylosis of the "burned out" rheumatoid joint. Lengthening of the limb across the joint could perhaps have been predicted byobserving the initial degree of preoperative bone erosion visible on the radiographs and comparing this with the radiographic appearances after a surface TEJR. This study provides objective evidence that this is the case and that by using the Kudo TEJR an overall lengthening of up to 17 mm may result . We consider that this is likely to be the case when other surface replacement designs are used to perform TEJR. Two major complications reported after TEJR are ulnar nerve injury and instability." 10 . 11 We believe that limb lengthening may be an important factor in the development of these compl ications, if specific preventative steps are not taken during the operative procedure. Elbow lengthening as a consequence ofTEJR will result in tensile forces passing across the elbow through the adjacent soft tissues and a corresponding compressive force across the camponents. We believe that this soft-tissue traction may include the ulnar nerve, because it is often observed at surgery in rheumatoid arthritis that fibrous adhesions tether the nerve at the point at which it passes between the two heads of origin of the flexor carp i ulnaris muscle. Ulnar nerve paresis complicating TEJR has been reported to occur as often as 31 % to 65% of cases in some series." 11 We found no case of ulnar nerve dysfunction in this series and believe that the incidence of this complication can be greatly reduced by widely mobilizing and decompressing the ulnar nerve during the surgical exposure. This prevents a chronic traction injury to the nerve from developing as a consequence of lengthening across the jo int after TEJR. We also believe this will explain the relatively high incidence of this complication in patients in whom a posterolateral approach has been used and
205
in whom the ulnar nerve is not visuolized but left" undisturbed." If the soft-tissue tensile forces occurring after elbow lengthening are not balanced, then joint stability is threatened. Instability may occur as a result of a tensile force passing through an intact but pathologically altered ulnar collateral ligament. Such asymmetric loading across an unconstrained prosthesis could result in a degree of hinging about the medial side resulting in distraction of the components on the lateral side of the joint, stressing the surgical repair and causing instability. Dislocation of the components remains a frequently encountered complication of unconstrained TEJR with reported rates between 6% and 29%.10.11 .13 We observed no dislocations or subluxations in this series. We believe that the incidence of dislocation after TEJR with unconstrained prostheses can be greatly reduced by a wide periarticular softtissue release including division and excision of the scarred and often ossified ulnar collateral ligament. A wide exposure sufficient to allow accurate component placement and optimal balance of the soft tissues can then be achieved. It is these two factors that ensure joint stability rather than the preservation of diseased and distorted periarticular soft tissues. Our clinical find ings suggest that such an approach will accommodate the restoration of normal joint ge ometry by insertion of a TEJR, resulting inevitably in lengthening across the joint and yet retaining a good range of movement, even in those patients in whom increases of length of up to 17 mm are observed .
REFERENCES 1. De Carvalho A. Graudal H. Jo rgensen B. Radiologic evaluat ion of the progression of rheumato id arthritis. Acto Radiol 1980;2 1: 115-21. 2. Ewald FC, Simmons ED, Sullivan JA. Thomas WH , Scott RD. Poss R, Thornhill TS, Sledge CB. Capitellocandylar tota l elbo w replacement in rheumato id arthritis. J Bone Joint Surg [Ami 1993;75A:498-507. 3. Goldberg VM, hggie HE, Inglis AE, Figg ie MP. Total elbow arthrop lasty. J Bone Joint Surg [Am] 1988;70A : 778-83 . 4. Hodgson SP, Parkinson RW, Noble J. Cap itellocondylor total elbow replacement for rheumatoid arthritis. J RCo li Surg Edinb 1991;36: 133-5 . 5. Inglis AE, Pellicci PM. Total elbow replacement. J Bone Joint Surg (Ami I 980;62A: 1252-8. 6. Kudo H, Iwa no K, Wa tanab e S. Total replacement of the rheumatoid elbow with a hingeless prosthesis. J Bone Joint Surg [AmI 1980;62A:277·85.
206 Blewitt and Pooley
7. Kudo H, Iwano K. Total elbow arthroplasty with a nonconstrained surface-replacement prosthesis in patients who have rheumatoid arthritis: A long-term follow-up study. J Bone Joint Surg [Ami 1990;72A:355-62. 8. Larsen A, Dale K, Eek M. Radiographic evaluation of rheumatoid arthritis and related conditions by standard reference films. Acta RadioI1977;18:481-91. 9. Last RJ. Anatomy regional & applied. Ed 7. Edinburgh: Churchill Livingstone, 198487-8.
J. Shoulder Elbow Surg. July/August 1994
11. Ruth JT, Wilde AH. Capitellocondylar total elbow replacement. A long-term follow-up study. J Bone Joint Surg [Arn] 1992;7495-100. 12. Souter WA. Arthroplasty of the elbow: With particular reference to metallic hinge arthroplasty in rheumatoid patients. Orthop Clin North Am 1973;4 :395-413. 13. Weiland AJ, Weiss AP, Wills RP, Moore JR Capitellocondylar total elbow replacement: A long-term followup study J Bone Joint Surg [Am] 1989;71 :217-22.
10. Rosenberg GM, Turner RH. Nonconstrained total elbow arthroplasty. Clin Orthap 1984; 187: 154-62.
Bound Volumes Available to Subscribers Bound volumes of the 1994 issues of JOURNAL Of SHOULDER AND ELBOW SURGERY are available to subscribers (only) from the publisher, at a cost of $51.50 for domestic, $61.11 for Canadian, and $57.50 for international subscribers, for Vol. 3 (January-December); shipping charges are included. Each bound volume contains subject and author indexes, and all advertising is removed. Copies are shipped within 60 days after publication of the last issue in the volume. The binding is durable buckram, with the journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mosby, Subscription Services, 11830 Westline Industrial Dr., St. Louis, MO 63146-3318, USA; phone (314)453-4351 or (800)453-4351.
Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular subscription.
Newcastle Upon Tyne, United Kingdom We have carried out a radiologic study to determine the effect on limb length of inserting the components of a total elbow [oin! replacement arthroplasty. The preoperative and postoperative radiographs of 27 consecutive patients undergoing total elbow ioint replacement arthroplasty with the Kudo prosthesis were studied. In all cases lengthening across the elbow was found. Both ulnar and humeral lengthening were observed. A mean length increase of 8.6 mm (range 2 to 77 mm) was recorded. Ulnar lengthening contributed to overall lengthening by a significantly greater amount than humeral lengthening . We correlated the degree of lengthening observed with clinical measurements in this series of patients but found no significant differences. Operative maneuvers are suggested to accommodate this length increase, to achieve soft-tissue balance, and to avoid potential complications such as ulnar neuropathy and ;oint instability. (J SHOULDER ELBOW SURG 7994;3:200-6)
The development of elbow prostheses suitable for general use began in the early 1970s when both fully constrained (linked) and semiconstrained (unlinked) implants were inserted and fixed with cement.' Examples include the Coonrad and the Triaxial prostheses.' Further study revealed that by imitating normal elbow kinematics and using less constrained implants, better results could be onticipoted." Such prostheses as the Souter/Strcthclyde," Capitellocondylar/ and the Kudo implcntsv" have confirmed this potential. At present the most common indication for total elbow joint replacement arthroplasty (TEJR) is rheumatoid disease. This disease affects the synovial joints by inducing inflammation and joint destruction with consequent painful loss of function. Joint destruction results from both bony erosion and From the University Deportment of Orthopaedics, Newcastle Upon Tyne. Reprint requests: N . BlewiH, FRCS, University Deportment of Orthopaedics, Newcastle Upon Tyne NEl 4LP, United Kingdom . Copyright © 1994 by Journal of Shoulder and Elbow Surgery Boord of Trustees. 1058-2746/94/$3.00 + 0 32/1/55146
200
periarticular soft-tissue inflammation with varying degrees of fibrosis. The overall effect is not only joint incongruity and painful limitation of movement but inevitably also a degree of pathologic shortening across the joint. We have observed lengthening across the joint after TEJR using the Kud0 6 • 7 unconstrained resurfacing prosthesis and report the clinical effect of lengthening on the patients studied.
MATERIAL AND METHODS Patients undergoing TEJR in our unit are studied prospectively. Preoperative recording of functional impairment and range of movement is entered onto standardized form, and both subjective and objective measurements are allocated scores (Table I). Subjective assessment includes the evaluation of function, pain, and analgesic requirements. Function is determined by ease or difficulty in performing certain basic act ivities such as feeding, washing, or dressing . Pain is measured with a visual analogue scale (15 for no pain, 0 for worst pain imaginable), and analgesia requirement is scored according to the presence of nocturnal pain and the required amounts and frequency of pain-relieving
J. Shoulder Elbow Surg. Volume 3, Number 4
Blewitt and Pooley
201
Figure 1 Rheumatoid arthritis is an erosive arthropathy resulting in joint destruction and pathologic joint shortening.
medication (low score for high frequency). Objective recordings include scores for the arc of motion and degree of fixed flexion . Muscle power is measured with the Medical Research Council (MRC) grading scale with a score of 5 allocated for normal motor power and 0 to indicate no active muscle contraction. Elbow stcbility is assessed by anteroposterior drawer testing and varus-valgus stressing. These clinical measurements were made both before surgery and 6 months after surgery in a consecutive series of 27 patients with rheumatoid arthritis in whom a Kudo TEJR was inserted . The shape of the components of the Kudo TEJR permits in addition to flexion and extension a degree of varus-valgus tilting and consequently rotation between humeral and ulnar components. This prosthesis therefore permits both hinging movement at the elbow and ulnar obduction and adduction, which take place during normal forearm pronation and supinotion.t ln this series the humeral component was inserted cementfree, and the ulnar component was cemented. After insertion of the components the wound was closed in layers with particular attention being directed to obtaining proper soft-tissue
Table Subjective and objective scores were obtained prospectively allowing comparison between preoperative and postoperative clinical scores Score (maximum) Subject ive Function Pain Analgesia requirement Subtotal Objective Range of motion Strength Stability Subtotal Overall total
36 15 ~
66
31 15 ~ ~ 118
balance, made possible by a wide surgical exposure. The anconeus muscle and its overlying fascia were repaired as a double layer to rein force this closure. After surgery the arm was rested in a lightweight splint for 3 to 5 days, and active physiotherapy was commenced within the limits of postoperative discomfort. The radiographs of these patients were as-
202
Blewitt and Pooley
J. Shoulder Elbow Surg. July/August 1994
Figure 2 Total joint replacement arthroplasty results in lengthening across elbow joint.
,\
A'
B'
R
Figure 3 Humeral lengthening is calculated by subtracting postoperative humeral length A-A' from preoperative humeral length A-A' , Ulnar lengthening is calculated by subtra cting postoperative ulnar length B-B' from preoperative ulnar length B-B' .
sessed before (Figure 1) and after (Figure 2) total elbow replacement. All the elbows were graded according to Larsen's clcssificotion" and were found to be either grade four or five. To determine whether lengthening had occurred across the joint as a result of the implantatian of the prosthetic components, ulnar and humeral lengths were measured on the preoperative and then on the postoperative radiographs (Figure 3). These measurements were recorded by a single observer. To ensure that
no error had been introduced as a result of magnification, the ulnar diaphyseal diameter was measured at a point 5 cm distal to the tip of the olecranon on both the preoperative and postoperative radiographs . In all cases it was confirmed that these two measurements were identical. The ulnar length was determined by measuring the distance of a perpendicular line drawn from the subcutaneous border of the ulnar to the estimated center of rotation of the elbow as judged on the lateral radiograph (ear-
J. Shoulder Elbow Surg. Volume 3, Number 4
Blewitt and Pooley
203
20
.
. . 15 •
. E
.s
.
----
10 '
:
J:.
e;,
UlNA
C
•
...J
Z
5•
•
HU ERUS
--o·
·5 · 1
2
3
4
5
e
7
& ;
10 11 12 13 14 15 1& 17 18 1; 20 21 22 23 24 25 28 27 en. Number
Figure 4 Lengthening after tota l elbow replacement. Lengthening was observed to occur in all cases studied . Ulnar lengthening co ntributed significantly more to overall lengthening tha n did hume ral lengthen ing .
lier studies in this department had verified this method of estimation by measuring reproducibility and interobserver error) . Any increase in ulnar length was then calculated by subtracting the length measured on the postoperative radiograph. The humeral length was measured by drawing a perpendicular line passing through the center of rotation of the elbow to a reference point on the lower humerus readily identifiable on the preoperative and postoperative radiographs. The cortex of the supracondylar ridge provided a convenient landmark in most cases; however, other points were also used providing that they could be confidently identified on both the preaperative and postoperative radiographs . The postoperative reference value was then subtracted from the preoperative value to determine absolute humeral lengthening (Figure 3). Overall joint lengthening after TEJR was then calculated for each case as the sum of the value obtained for ulnar lengthening and the value obtained for humeral lengthening.
RESULTS All the elbows in this series were lengthened as result of TEJR. The overall results are presented in Figure 4. The mean overall length-
ening was found to be 8.6 mm (ronqe 2 to 17 mm). This mean lengthening was not contributed to equally by ulnar and humeral components. The mean ulnar lengthening was 6.6 mm (range 1 to 14 mm), and the mean value for humeral lengthening was 2.0 mm (range 2 to 9 mm). Analysis of these findings with the t test for matched data pairs identified a highly significant difference between ulnar and humeral lengthening. The "t value" was 4.9, which is greater than the critical tvalue of 3.43 required to achieve a significance level for p = 0.001. Clinical relevance. Having identified a mean lengthening across the elbow of 8.6 mm after TEJR in this series , we consulted the prospective clinical data obtained from these patients. We divided these patients into two groups, one group in whom the total measured lengthening was found to be greater than 9 mm and another group in whom the lengthening was found to be less than 9 mm. Before surgery we found no difference in either the subjective or objective scores between these two groups. These clinical scores together with those scores recorded 6 months after surgery are shown in Figures 5 and 6. It can be seen that there was no significant difference between the postoperative scores, either. There was, however, a
204 Blewitt and Pooley
J. Shoulder Elbow Surg. July/ August 1994
3S
30
2S
20 •
!
0
u
en
1S
--J
mean<9mm
~ :~n>9mm
,,--(
I 1
10
I
I
S~
I
o. Function
Analgesia
Pain
ROM
Stabtlit y
Strength
Figure 5 Preoperative clinical scores. There was na d ifference in preoperative clinical scores observed between two g roups . 3S
30
2S
20
I mea;";:~ ] ,,-,
!
0
u
I
Ul
..,
1S j
mean>9mm
r I I I
10
S
o· Fund,on
Pain
AnalgeSia
ROM
Strength
Stabtlity
Figure 6 Postoperative clinical scores . Comparing pos toperative clinical scores of group lengthened less than 9 mm w ith group lengthened more than 9 mm, no statistically sign ificant difference was noted. Range-of -mo tion scores tended to be better in the group lengthened by more than 9mm.
higher mean score for postoperative range of movement in the group with a measured length increase of more than 9 rnrn: this difference was found not to be statistically significont with the Wilcoxon rank sum test for unpaired data.
DISCUSSION Rheumatoid arthritis is an erosive inflammatory arthropathy manifested in the elbow as in other joints by bone destruction and soft-tissue changes. Articular cartilage is lost and under-
Blewitt and Pooley
J. Shoulder Elbow Surg. Volume 3, Number 4
lying bone is eroded. Periarticular soft tissue becomes inflamed, and later fibrosis and scarring develop. The net result is not only joint destruction with painful functional impairment but also a change in limb geometry as pathologic shortening across the joint inevitably occurs. 1 This shortening begins with loss of articular cartilage and is accentuated by underlying bony eros ion, and progression occurs associated with fibrotic contraction of inflamed periarticular soft tissues. This progression ultimately results in the ankylosis of the "burned out" rheumatoid joint. Lengthening of the limb across the joint could perhaps have been predicted byobserving the initial degree of preoperative bone erosion visible on the radiographs and comparing this with the radiographic appearances after a surface TEJR. This study provides objective evidence that this is the case and that by using the Kudo TEJR an overall lengthening of up to 17 mm may result . We consider that this is likely to be the case when other surface replacement designs are used to perform TEJR. Two major complications reported after TEJR are ulnar nerve injury and instability." 10 . 11 We believe that limb lengthening may be an important factor in the development of these compl ications, if specific preventative steps are not taken during the operative procedure. Elbow lengthening as a consequence ofTEJR will result in tensile forces passing across the elbow through the adjacent soft tissues and a corresponding compressive force across the camponents. We believe that this soft-tissue traction may include the ulnar nerve, because it is often observed at surgery in rheumatoid arthritis that fibrous adhesions tether the nerve at the point at which it passes between the two heads of origin of the flexor carp i ulnaris muscle. Ulnar nerve paresis complicating TEJR has been reported to occur as often as 31 % to 65% of cases in some series." 11 We found no case of ulnar nerve dysfunction in this series and believe that the incidence of this complication can be greatly reduced by widely mobilizing and decompressing the ulnar nerve during the surgical exposure. This prevents a chronic traction injury to the nerve from developing as a consequence of lengthening across the jo int after TEJR. We also believe this will explain the relatively high incidence of this complication in patients in whom a posterolateral approach has been used and
205
in whom the ulnar nerve is not visuolized but left" undisturbed." If the soft-tissue tensile forces occurring after elbow lengthening are not balanced, then joint stability is threatened. Instability may occur as a result of a tensile force passing through an intact but pathologically altered ulnar collateral ligament. Such asymmetric loading across an unconstrained prosthesis could result in a degree of hinging about the medial side resulting in distraction of the components on the lateral side of the joint, stressing the surgical repair and causing instability. Dislocation of the components remains a frequently encountered complication of unconstrained TEJR with reported rates between 6% and 29%.10.11 .13 We observed no dislocations or subluxations in this series. We believe that the incidence of dislocation after TEJR with unconstrained prostheses can be greatly reduced by a wide periarticular softtissue release including division and excision of the scarred and often ossified ulnar collateral ligament. A wide exposure sufficient to allow accurate component placement and optimal balance of the soft tissues can then be achieved. It is these two factors that ensure joint stability rather than the preservation of diseased and distorted periarticular soft tissues. Our clinical find ings suggest that such an approach will accommodate the restoration of normal joint ge ometry by insertion of a TEJR, resulting inevitably in lengthening across the joint and yet retaining a good range of movement, even in those patients in whom increases of length of up to 17 mm are observed .
REFERENCES 1. De Carvalho A. Graudal H. Jo rgensen B. Radiologic evaluat ion of the progression of rheumato id arthritis. Acto Radiol 1980;2 1: 115-21. 2. Ewald FC, Simmons ED, Sullivan JA. Thomas WH , Scott RD. Poss R, Thornhill TS, Sledge CB. Capitellocandylar tota l elbo w replacement in rheumato id arthritis. J Bone Joint Surg [Ami 1993;75A:498-507. 3. Goldberg VM, hggie HE, Inglis AE, Figg ie MP. Total elbow arthrop lasty. J Bone Joint Surg [Am] 1988;70A : 778-83 . 4. Hodgson SP, Parkinson RW, Noble J. Cap itellocondylor total elbow replacement for rheumatoid arthritis. J RCo li Surg Edinb 1991;36: 133-5 . 5. Inglis AE, Pellicci PM. Total elbow replacement. J Bone Joint Surg (Ami I 980;62A: 1252-8. 6. Kudo H, Iwa no K, Wa tanab e S. Total replacement of the rheumatoid elbow with a hingeless prosthesis. J Bone Joint Surg [AmI 1980;62A:277·85.
206 Blewitt and Pooley
7. Kudo H, Iwano K. Total elbow arthroplasty with a nonconstrained surface-replacement prosthesis in patients who have rheumatoid arthritis: A long-term follow-up study. J Bone Joint Surg [Ami 1990;72A:355-62. 8. Larsen A, Dale K, Eek M. Radiographic evaluation of rheumatoid arthritis and related conditions by standard reference films. Acta RadioI1977;18:481-91. 9. Last RJ. Anatomy regional & applied. Ed 7. Edinburgh: Churchill Livingstone, 198487-8.
J. Shoulder Elbow Surg. July/August 1994
11. Ruth JT, Wilde AH. Capitellocondylar total elbow replacement. A long-term follow-up study. J Bone Joint Surg [Arn] 1992;7495-100. 12. Souter WA. Arthroplasty of the elbow: With particular reference to metallic hinge arthroplasty in rheumatoid patients. Orthop Clin North Am 1973;4 :395-413. 13. Weiland AJ, Weiss AP, Wills RP, Moore JR Capitellocondylar total elbow replacement: A long-term followup study J Bone Joint Surg [Am] 1989;71 :217-22.
10. Rosenberg GM, Turner RH. Nonconstrained total elbow arthroplasty. Clin Orthap 1984; 187: 154-62.
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