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Dorsal Distal Radius Pedicled Vascularized Bone Grafting for Avascular Necrosis of the Carpus
Dorsal Distal Radius Pedicled Vascularized Bone Grafting for Avascular Necrosis of the Carpus Peter C. Rhee, DO, and Alexander Y. Shin, MD Although avascular necrosis can occur in any of the carpal bones, they more commonly affect the scaphoid (Preiser disease) and the lunate (Kienbock disease). Many revascularization options have been described, mostly pedicled vascularized bone grafts from the volar and dorsal aspect of the distal radius and carpus. Pedicled vascularized bone grafts from the dorsal distal radius is rooted on a consistent and rich arterial network that allows for many different donor sites based on the location of the recipient carpal bone. In the treatment of Preiser disease and Kienbock disease, we prefer to use the 1,2-intercompartmental supraretinacular artery and the 4th ⴙ 5th extensor compartment artery pedicled dorsal distal radius bone grafts. Oper Tech Orthop 22:151-158 © 2012 Elsevier Inc. All rights reserved. KEYWORDS vascularized bone graft, distal radius, avascular necrosis, scaphoid nonunion, Kienbock’s disease
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edicled vascularized bone grafts (VBGs) from the dorsal distal radius have been used for a variety of carpal pathologies.1-3 Use of VBGs is attractive for the potential to recolonize the host site with osteoprogenitor cells.4,5 Transplantation of viable osteocytes (greater than 90% survival for VBGs) is believed to result in an accelerated process of graft– host union through primary bone healing without resorption or creeping substitution.4-7 Additionally, the robust corticocancellous bone able to be harvested from the distal dorsal radius allows for replacement of deficient bone stock and provides structural integrity.4,5 Most importantly, dorsal distal radius VBGs have the ability to introduce, maintain, and increase (up to 4-fold) vascularity to the recipient carpal bone from the donor vascular pedicle.8 As such, dorsal distal radius pedicled VBGs are a powerful treatment option for avascular necrosis (AVN) of the carpus compared with conventional non-VBGs.9 A variety of pedicled dorsal distal radius VBGs have been described rooted on a consistent and reliable arterial network.2,3,10 Initially, Zaidemberg reported the use of a pedicled VBG from the radial styloid based on an “ascending irrigating branch” from the radial artery for the treatment scaphoid nonunion. Subsequently, an extensive cadaveric
Division of Hand Surgery, Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN. Address reprint requests to Alexander Y. Shin, MD, Division of Hand Surgery, Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905. E-mail: [email protected]
1048-6666/12/$-see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1053/j.oto.2012.07.003
study performed by Sheetz et al10 correctly defined this pedicle as the 1,2-intercompartmental supraretinacular artery (1,2-ICSRA)1 and detailed the pattern of extraosseous arterial blood supply to the distal radius. This provided the framework for reliable anatomic landmarks to identify and use multiple dorsal distal radius vascular pedicles for VBGs in antegrade or retrograde flow manner. When compared with volarly based VBGs, retrograde-flow dorsal distal radius VBGs are easier to harvest and result in less donor-site morbidity.11 The criteria for VBGs of the distal radius include (1) sufficient length from harvest to donor site without risk of pedicle kinking, (2) must provide nutrient vessels to both cortical and cancellous bone, and (3) provide adequate blood flow to maintain viability.12 Although pedicled dorsal distal radius VBGs can theoretically be used to address AVN of the entire carpus, they are more commonly used to address pathology of the scaphoid. Recently, the 1,2-ICSRA has gained popularity toward the treatment of scaphoid nonunions with or without AVN of the proximal pole.1,2,13-17 However, its use has been reported toward the treatment scaphoid AVN (Preiser disease).18,19 Little is known regarding the etiology of Preiser disease; however, disruption of the blood supply to the scaphoid has been heavily measured.20,21 Because of the lack of evidence-based medicine (consisting of small series and case reports), optimal treatment options are varied22-26 and based on the stage of the disease, as described by Herbert and Lanzetta.27 The use of VBGs is limited to early disease in the setting of an intact cartilaginous shell without radiocarpal or mid-carpal 151
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arthritis.18,28 A few VBGs have been described for the treatment of early Preiser disease, including a pronator pedicle,29 implantation of a vascular bundle,30,31 and dorsal distal radius VBGs with the 1,2- and 2,3-ICSRA.18,19 VBG has also gained popularity in the treatment of lunate AVN (Kienbock disease). The etiology of Kienbock disease is speculative; however, many believe that anatomic,32 vascular,21,33 and biomechanical factors (increased load transmission due to ulnar minus variance)34,35 may play a role. Nonetheless, a predictable pattern of arthritis and collapse occur.36,37 Treatment options are based on the Stahl-Lichtman classification38 and include joint-leveling procedures (ulnar lengthening or radial shortening),39,40 lateral closing wedge osteotomy,41 or partial wrist arthrodesis for early stages.42 A myriad of VBGs have been used in the setting of an intact cartilage shell without radiocarpal or midcarpal arthroses, including a pedicled vascular pisiform43,44 or scaphoid tubercle,45 pronator quadratus,29 dorsal metacarpal arteriovenous bundle implantation,31,46 and the 4th ⫹ 5th extensor carpal artery (4 ⫹ 5 ECA) VBG.3,47 Techniques for VBGs to the lunate have been varied with or without joint-leveling procedures.44
Anatomy The complex arterial network to the distal dorsal radius was elucidated by Sheetz et al.10 Four extraosseous vessels (radial, ulnar, anterior, and posterior interosseous arteries) provide nutrient vessels to the distal radius and ulna. The anterior interosseous artery divides into the anterior and posterior divisions. The latter, combined with the radial artery, represent the primary source of antegrade flow to the distal dorsal radius. Four nutrient vessels originate from these vessels, which serve as pedicles to the distal dorsal radius VBGs. They are named according to their course relative to the extensor compartments (ECAs) and retinaculum. There are two intercompartmental vessels that reside on top of the retinaculum (supraretinacular) between the named ECAs: the 1,2-ICSRA and 2,3-ICSRA. Additionally, there are two vessels that rest within the floor of their respective ECAs: the 4th and 5th ECA (Fig. 1).10 Distal to these vessels, arterial arches in series across the dorsum of the wrist serve as a distal anastomotic network for the ICSRA and ECA (dorsal intercarpal arch, dorsal radiocarpal arch, and the dorsal supraretinacular arch). The dorsal intercarpal arch plays a pivotal role connecting the ICSRAs and ECAs, which allows for distally based reversed flow VBGs after proximal ligation, and serves the basis for most of the distal dorsal radius VBGs. The major limiting factor in terms of the various distal dorsal radius VBGs is the arc of motion of each harvested graft.10 In the treatment of Preiser disease and Kienbock disease, we prefer to use the 1,2-ICSRA (Fig. 2A) and the combined 4 ⫹ 5 ECA (Fig. 2B), respectively. The 1,2-ICSRA originates from the radial artery approximately 5 cm proximal to the radiocarpal joint and travels deep to the brachioradialis, on top of the extensor retinaculum, toward the anatomic snuffbox where it joins the radial artery, and/or the radiocarpal arch. This artery is present in 94% of cadaveric spec-
Figure 1 Vascular anatomy of the dorsal distal radius. Two arteries course between the dorsal extensor compartments (ECA), the 1,2and the 2,3-intercompartmental supraretinacular artery (ICSRA), and 2 arteries travel within the ECA, the 4th and 5th ECA. These arteries can be used as pedicles for vascularized bone grafts to the scaphoid or the lunate, respectively. RA ⫽ radial artery, UA ⫽ ulnar artery, dICa ⫽ dorsal intercarpal artery, dRCa ⫽ dorsal radiocarpal artery, dSRa ⫽ dorsal supraretinacular artery, AIA ⫽ anterior interosseous artery, PIA ⫽ posterior interosseous artery, aAIA ⫽ anterior division of the anterior interosseous artery, and pAIA ⫽ posterior division of the anterior interosseous artery. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
imens, travels with two venae comitantes, provides on average 3.2 nutrient arteries, of which 6% penetrate into cancellous bone at a mean distance of 15 mm proximal to the joint line.10 With a mean internal diameter of 0.3 mm, it is the smallest of the 4 distal dorsal radius vessels. The short arc of rotation limits its use toward treatment of the scaphoid. The 4th ECA originates from the posterior division of the anterior interosseous artery and courses along the floor of the 4th ECA, adjacent to the posterior interosseous nerve. The 4th ECA has been shown to be present in 100% of cadaveric specimens. An average of 3.2 nutrient arteries are present at a mean distance of 11 mm proximal to the joint line. Up to 45% of the nutrient vessels penetrate deep into the cancellous bone.10 Conversely, the 5th ECA rarely provides nutrient vessels to the distal dorsal radius, as it travels along the radial floor of the 5th ECA. However, because of its large internal diameter (mean 0.49 mm) and multiple sites of distal anastomoses (dorsal intercarpal arch, 4th ECA, dorsal radiocarpal arch, 2,3-ICSRA, and the oblique dorsal artery of the distal ulna), it serves as an excellent conduit for retrograde flow to the 4th ECA.10,48
Dorsal distal radius pedicled vascularized bone grafting
153 (MRI) alterations involving the whole scaphoid (with the exception of the distal tubercle).25 The treatment algorithm for Preiser disease continues to be defined; however, our indications for the use of VBGs for the treatment of scaphoid AVN is restricted to early-stage disease (Herbert stage I or II, Table 1) without degenerative change at the radiocarpal or midcarpal joints, nor carpal collapse.27 We also use the system defined by Kalainov et al28 to grade the scaphoid’s avascular status as generalized (type I) or segmental vascular impairment (type II) on magnetic imaging resonance studies with intravenous gadolinium.19 In our experience, the former (generalized AVN of the scaphoid) is technically more demanding, as it is difficult to remove all necrotic bone without breeching the cartilage shell.18 Our preferred distal dorsal radius VBG is the 1,2-ICSRA, and the 2,3-ICSRA serves as a salvage.18,19 If, at the time of surgery, radiocarpal arthritis is present, then revascularization is contraindicated, and a salvage procedure, such as scaphoidectomy and four-corner arthrodesis or proximal row carpectomy, is performed.
1,2-Intercompartmental Supraretinacular Artery Graft Technique
Figure 2 Pedicled dorsal distal radius vascularized bone graft arc of rotation. (A) 1,2-intercompartmental supraretinacular artery (1,2ICSRA) and the (B) 4 ⫹ 5 ECA artery (4 ⫹ 5 ECA). (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
The technique is similar for VBG in the treatment of scaphoid nonunion.49 The patient is positioned supine with the affected extremity positioned on a hand table. After an unsterile tourniquet is applied to the upper arm, the extremity is prepped and draped. The extremity is elevated, and the tourniquet is inflated only to 200 mm Hg without exsanguination. This allows for better visualization of the donor vessels. A curvilinear (S-shaped) incision is placed over the 1st and 2nd ECA (Fig. 3A). Sharp dissection is performed, taking care to identify and protect the superficial branch of the radial nerve, down to the 1,2-ICSRA, and accompanying two vena comitantes located between the 1st and 2nd ECAs, which lie above the retinaculum (Fig. 3B). The vessel is dissected distally to its anastamoses with the radial artery. The bone graft region is centered 15 mm proximal to the radiocarpal joint to maximize retention of the nutrient vessels. The 1st and 2nd ECAs are opened, maintaining a cuff of retinacular tissue on either side of the vessels, the associated extensor tendons are retracted ulnarly and radially. The 1,2-ICSRA and veins are left adherent to the bone at the graft site, then ligated proximal to the graft site. After the retinacular tissue has been elevated in line with the graft, an osteotomy is performed with a microsagittal saw and elevated with small (2 mm) osteotomes (Fig. 4A). For distal cuts, the 1,2-ICSRA and veins are retracted radially Table 1 Stages of Preiser’s Disease: Herbert Classification
Preiser Disease (Avascular Necrosis of the Scaphoid)
Stage 1
Stage 2
Indication/Contraindication The diagnosis of Preiser disease include (1) absence of trauma and/or prior wrist procedures, (2) radiologic alteration in at least 80% of the bone, and (3) magnetic resonance imaging
Stage 3 Stage 4
Normal radiographs Positive bone scan Positive MRI finding Proximal pole increased density on radiographs Generalized osteoporosis Proximal pole fragmentation ⴞ fracture on radiographs Carpal collapse with osteoarthritis
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ternal fixation or scaphocapitate pins if a large bone defect had been encountered (Kalainov et al28 type II).19 Hemostasis is obtained, and the wound is thoroughly irrigated. The capsule does not need to be sutured back; however, this may be performed cautiously as to not cause impediment to flow through the pedicle. The incision is closed with nonabsorbable sutures. The extremity is placed into a well-padded long arm thumb spica splint with the wrist in neutral position.
Rehabilitation Range of motion exercises are allowed at the fingers and shoulder immediately. At 2 weeks postoperative, the sutures are removed, and the arm is placed into a long arm thumb spica cast for an additional 10 weeks in neutral wrist position. At the time of cast removal, radiographs are obtained to assess for fracture healing. If external fixation or pins were used, these are removed at this time as well. At 12 weeks postoperative, wrist range of motion and strengthening exercises are initiated, and the patient is gradually weaned out of the splint.
Figure 3 Surgical approach to the 1,2-intercompartmental supraretinacular artery (1,2-ICSRA) vascularized bone graft. (A) Curvilinear incision centered over the 1st and 2nd ECA. (B) Identification of the 1,2-ICSRA between the 1st and 2nd ECA. S ⫽ scaphoid, R ⫽ radius, RA ⫽ radial artery, I ⫽1st ECA, II ⫽ second ECA, III ⫽3rd ECA, SBRN ⫽ superficial branch of the radial nerve. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
and then ulnarly to protect the vessels. If desired, the tourniquet can be deflated to check for arterial perfusion. A transverse, dorsal-radial capsulotomy is made ulnar to the 1,2-ICSRA vessels to in line with of the radiotriquetral ligaments (dorsal intercarpal ligament). Up to one-half of the radiotriquetral ligament can be divided if needed to facilitate exposure of the scaphoid.49 A dorsal cortical window is prepared within the scaphoid, through which all necrotic and sclerotic bone is removed using a combination of power burr and curettes, taking care to preserve the cartilaginous shell.19 The bone graft is transplanted into the bone defect, additional distal radius bone graft can be packed into the scaphoid if needed. The inlay graft can be stabilized with Kirschner wires (K-wires) or simply press fit (Fig. 4B). It is important to take care when tamping the bone graft as to not cause direct trauma to the vessels. If early arthritic change is noted at the radiostyloid joint, then a radial styloidectomy can also be performed. Rarely, the radial styloid may need to be removed if vascular pedicle impingement is encountered. Although unloading of the scaphoid has not been shown to provide an additional benefit,19,28 we reserve the use of ex-
Figure 4 1,2-ICSRA vascularized bone graft harvest and insetting. (A) Bone graft harvest centered over the 1,2-ICSRA. (B) Insetting of the 1,2-ICSRA vascularized bone graft, initially secured with percutaneous pins fixation. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
Dorsal distal radius pedicled vascularized bone grafting Table 2 Stages of Kienbock’s Disease: Stahl-Lichtman Classification Stage 1 Normal radiographs Positive bone scan Positive MRI finding Stage 2 Lunate increased density without collapse on radiographs Stage 3 Lunate collapse with partial or complete sclerosis (a) proximal row remained aligned (b) proximal row malaligned and destabilized Stage 4 Lunate fragmentation with degenerative changes at the radiocarpal and/or midcarpal joint
155 ECA as the pedicle (4 ⫹ 5 ECA) in the treatment of Kienbock disease. This allows retrograde flow through the 5th ECA and antegrade flow to the 4th ECA by ligation of the posterior branch of the anterior interosseous artery.3 The advantages to the 4 ⫹ 5 ECA are its (1) large pedicle diameter, (2) long pedicle length, (3) and the pedicle’s ulnar location in the wrist, which decreases risk of injury to the vessels with a dorsal arthrotomy.3
Complications Potential complications include superficial branch of the radial nerve neuritis, extensor tendon laceration, iatrogenic fractures of the distal radius, or progression of scaphoid AVN and fragmentation. In a study performed by Moran et al,19 there were no complications noted in 6 patients who underwent 1,2-ICSRA for Preiser disease. Only one patient required an additional surgery (proximal row carpectomy) for continued pain, despite MRI evidence of scaphoid revascularization.
Kienbock Disease (Avascular Necrosis of the Lunate) Indication/Contraindication Historically, VBGs have been indicated in the treatment of early stage of Kienbock disease without carpal collapse (Lichtman stage I to IIIa, Table 2), particularly when joint level procedures are contraindicated (ulnaneural or positive variance). More importantly, an intact cartilage shell (without fracture or fragmentation) and without evidence of carpal arthrosis is necessary for dorsal distal radius VBG.50 Although this can be assessed with CT and MRI, if any ambiguity exists, we routinely use wrist arthroscopy (without the 4-5 or ulnar midcarpal portal to prevent injury to the 4th or 5th ECA)48 to confirm the absence of wrist arthrosis and status of the lunate articular surface. The presence of carpal collapse is not a contraindication if the integrity of the articular cartilage shell has been maintained (stage IIIb). Thus, the ideal indication is an ulnar neutral stage II-IIIa/b without fragmentation of the lunate. Revascularization is contraindicated when associated radiocarpal and midcarpal arthritis is present. Generally, VBGs should not be performed if the lunate is fractured with extrusion or if the articular cartilage shell has been breached. A relative contraindication is a history of a prior dorsal wrist procedure due to the potential for dorsal wrist arterial network disruption.50 Although the 4th ECA can be used as the pedicle, we prefer to use the 4th ECA dorsal distal radius bone graft with the 5th
Figure 5 Approach to the 4 ⫹ 5 ECA. (A) Dorsal midline approach identifying the 4th and 5th ECA. (B) Ligament-sparing dorsal wrist arthrotomy and region of bone graft harvest. ECA, extensor compartment artery. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
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4 ⴙ 5 ECA Artery Graft Technique The surgical positioning and preparation is similar to that described for the 1,2-ICSRA. The arm is not exsanguinated before tourniquet inflation to assist with vessel identification. A longitudinal incision is made in line with the 3rd metacarpal. The 5th dorsal ECA is entered, and the 5th ECA (with vena comitantes) is identified in the radial aspect of the compartment (Fig. 5A). The 5th ECA is typically adjacent to or partially within the septum, separating the 4th and 5th dorsal ECA. The vessel is traced to its origin from the anterior interosseous artery. At this confluence, the 4th ECA origin is identified, and the vessel is traced distally. A radially based extensor retinacular flap is developed from the 5th to the 2nd ECA to allow adequate exposure of the dorsal wrist capsule (Fig. 5B). A dorsal ligament-sparing capsulotomy51 is made at the radiocarpal joint to visualize the lunate (care is maintained to preserve the 5th ECA as it courses of the dorsal wrist capsule). The lunate is inspected for fragmentation, collapse, or breach of the articular shell, and the presence of arthroses. If any of these are present, attempt at revascularization is abandoned, and a salvage procedure is performed. If revascularization is still indicated, a combination of high speed burr and curettes are used to create a dorsal hole within the lunate, through which necrotic bone is removed. Fluoroscopy can be used to ensure careful curettage without chondral breach. If the articular shell has collapsed after debridement, a blunt tip spreader can be used to carefully expand the articular shell (Fig. 6). The bone graft region is marked, usually centered approximately 1.1 cm proximal to the radiocarpal joint over the 4th
ECA.48 The bone graft should be slightly larger than needed to allow for trimming and insetting. The graft’s proximal– distal length represents the depth of the excavated defect, whereas the radioulnar width indicates the anteroposterior dimension.48 The 4th and 5th ECA are elevated from the dorsal distal radius with cuff of periosteum on each end, the 4th ECA is kept intact with the corticoperiosteal surface near the bone graft site. The posterior division of the anterior interosseous artery is ligated, proximal to the 4th and 5th ECA origin. The bone graft is elevated using a microsagittal saw and thin osteotomes (Fig. 7A). The tourniquet can be deflated at this time to ensure adequate vascularity. We have now abandoned this confirmatory step, as subsequent hemorrhage adds difficulty to the remainder of the case. Additional dorsal distal radius bone graft is harvested through the donor graft bed and packed within the lunate. A central cavity is prepared for insertion of the VBG, which is inserted with the pedicle oriented vertically and the cortical surface aligned proximal to distal to serve as a strut for maintenance of lunate height during revascularization.48 The VBG can be press fit as an inlay graft; therefore, internal fixation is not necessary (Fig. 7B). Lunate is vulnerable to recurrent collapse during revascularization52 and early loading can be detrimental12,53; therefore, we temporarily pin the intercarpal joint to unload the lunate. The scaphocapitate joint is pinned with a 0.0625-inch K-wire under approximately 10 lbs of longitudinal traction. After irrigation of the wound, the donor site can be packed with cancellous allograft or calciumbased bone graft substitute. The capsule and retinaculum are repaired cautiously as to not impede or kink the pedicle. The
Figure 6 Debridement of the lunate. A dorsal cortical window is made into the lunate with a burr. After necrotic bone removal, the lunate articular cartilage shell can be gently expanded with a blunt tip spreader. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
Dorsal distal radius pedicled vascularized bone grafting
157 ECA, both were pin tract infections. Two patients required wrist arthrodesis for persistent pain.
Conclusions Many revascularization options have been described to address AVN of the carpus, specifically the scaphoid (Preiser disease) and lunate (Kienbock disease). Pedicled dorsal distal radius VBGs are advantageous because of a consistent arterial network, which allows for multiple donor options based on the location of the recipient carpal bone. Although many different VBGs have been described for the treatment of Preiser disease and Kienbock disease, we prefer to use the 1,2ICSRA and the 4 ⫹ 5 ECA, respectively.19,33
References
Figure 7 4 ⫹ 5 ECA vascularized bone graft harvest and insetting. (A) Bone graft harvest after proximal vessel ligation. (B) Insetting of the 4 ⫹ 5 ECA vascularized bone graft into the lunate. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
skin is closed with nonabsorbable suture, and the arm is placed in to a long-arm splint.
Rehabilitation Immediate motion is allowed through the fingers and the shoulder for edema control. At 2 weeks postoperative, the sutures are removed and a long arm cast is applied for an additional 4 weeks. At 6 weeks postoperative, the cast is removed, and a removable short-arm volarly based plaster splint is fabricated, which is worn full time for an additional 6-8 weeks. Supervised therapy is initiated for gentle wrist flexion and extension stretching exercises. At 12 weeks postoperative, the scaphocapitate pins are removed, and wrist strengthening exercises are started. The patient is gradually weaned out of the splint after pin removal.
Complications Potential complications include extensor tendon laceration, pin tract infections, and iatrogenic fracture through the distal radius. In a series by Moran et al,3 there were 2 complications in 26 patients with Kienbock disease treated with the 4 ⫹ 5
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36.
bone graft from the dorsum of the distal radius. J Hand Surg Br 23:686-690, 1998 Rizzo M, Moran SL: Vascularized bone grafts and their applications in the treatment of carpal pathology. Semin Plast Surg 22:213-227, 2008 Moran SL, Cooney WP, Shin AY: The use of vascularized grafts from the distal radius for the treatment of Preiser’s disease. J Hand Surg Am 31:705-710, 2006 Taleisnik J, Kelly PJ: The extraosseous and intraosseous blood supply of the scaphoid bone. J Bone Joint Surg Am 48:1125-1137, 1966 Gelberman RH, Menon J: The vascularity of the scaphoid bone. J Hand Surg Am 5:508-513, 1980 Vidal MA, Linscheid RL, Amadio PC, et al: Preiser’s disease. Ann Chir Main Memb Super 10:227-235, 1991 Ekerot L, Eiken O: Idiopathic avascular necrosis of the scaphoid. Case report. Scand J Plast Reconstr Surg 15:69-72, 1981 Menth-Chiari WA, Poehling GG: Preiser’s disease: Arthroscopic treatment of avascular necrosis of the scaphoid. Arthroscopy 16:208-213, 2000 De Smet L, Aerts P, Walraevens M, et al: Avascular necrosis of the carpal scaphoid: Preiser’s disease: Report of 6 cases and review of the literature. Acta Orthop Belg 59:139-142, 1993 Kadji O, Duteille F, Dautel G, et al: Four bone versus capitolunate limited carpal fusion. Report of 40 cases. Chir Main 21:5-12, 2002 Herbert TJ, Lanzetta M: Idiopathic avascular necrosis of the scaphoid. J Hand Surg Br 19:174-182, 1994 Kalainov DM, Cohen MS, Hendrix RW, et al: Preiser’s disease: Identification of two patterns. J Hand Surg Am 28:767-778, 2003 Braun R: Pronator pedicle bone grafting in the forearm and proximal row. Orthop Trans 7:35, 1983 Kawanishi K: Treatment of scaphoid necrosis with vascular bundle implantation. J Jpn Soc Surg Hand 4:670-674, 1991 Hori Y, Tamai S, Okuda H, et al: Blood vessel transplantation to bone. J Hand Surg Am 4:23-33, 1979 Tsuge S, Nakamura R: Anatomical risk factors for Kienböck’s disease. J Hand Surg Br 18:70-75, 1993 Williams CS, Gelberman RH: Vascularity of the lunate. Anatomic studies and implications for the development of osteonecrosis. Hand Clin 9:391-398, 1993 Werner FW, Palmer AK: Biomechanical evaluation of operative procedures to treat Kienböck’s disease. Hand Clin 9:431-443, 1993 Horii E, Garcia-Elias M, Bishop AT, et al: Effect on force transmission across the carpus in procedures used to treat Kienböck’s disease. J Hand Surg Am 15:393-400, 1990 Beckenbaugh RD, Shives TC, Dobyns JH, et al: Kienböck’s disease: The natural history of Kienböck’s disease and consideration of lunate fractures. Clin Orthop Relat Res 149:98-106, 1980
37. Kristensen SS, Thomassen E, Christensen F: Kienböck’s disease—Late results by non-surgical treatment. A follow-up study. J Hand Surg Br 11:422-425, 1986 38. Lichtman DM, Degnan GG: Staging and its use in the determination of treatment modalities for Kienböck’s disease. Hand Clin 9:409-416, 1993 39. Trail IA, Linscheid RL, Quenzer DE, et al: Ulnar lengthening and radial recession procedures for Kienböck’s disease. Long-term clinical and radiographic follow-up. J Hand Surg Br 21:169-176, 1996 40. Weiss AP, Weiland AJ, Moore JR, et al: Radial shortening for Kienböck disease. J Bone Joint Surg Am 73:384-391, 1991 41. Nakamura R, Tsuge S, Watanabe K, et al: Radial wedge osteotomy for Kienböck disease. J Bone Joint Surg Am 73:1391-1396, 1991 42. Sennwald GR, Ufenast H: Scaphocapitate arthrodesis for the treatment of Kienböck’s disease. J Hand Surg Am 20:506-510, 1995 43. Saffar P: Remplacement du semi-lunaire par le pisiforme. Description d’une nouvelle technique pour te traitement de la maladie de Kienbock [in French]. Ann Chir Main 1:276-279, 1982 44. Daecke W, Lorenz S, Wieloch P, et al: Lunate resection and vascularized Os pisiform transfer in Kienböck’s disease: An average of 10 years of follow-up study after Saffar’s procedure. J Hand Surg Am 30:677684, 2005 45. Roy-Camille R: Fractures et pseudarthroses du scaphoide moyen. Utilisation d’un greffo pedicule [in French]. Actual Chir Ortho R Poincare 4:197-214, 1965 46. Tamai S, Yajima H, Ono H: Revascularization procedures in the treatment of Kienböck’s disease. Hand Clin 9:455-466, 1993 47. Shin AY, Bishop AT: Treatment of Kienböck’s disease with dorsal distal radius pedicled vascularized bone grafts. Atlas Hand Clin 4:91-118, 1999 48. Kakar S, Shin AY: Vascularized bone grafting from the dorsal distal radius for Kienböck’s disease: Technique, indications and review of the literature. Chir Main 29(suppl 1):S104-S111, 2010 49. Larson AN, Bishop AT, Shin AY: Dorsal distal radius vascularized pedicled bone grafts for scaphoid nonunions. Tech Hand Up Extrem Surg 10:212-223, 2006 50. Elhassan BT, Shin AY: Vascularized bone grafting for treatment of Kienböck’s disease. J Hand Surg Am 34:146-154, 2009 51. Berger RA: A method of defining palpable landmarks for the ligamentsplitting dorsal wrist capsulotomy. J Hand Surg Am 32:1291-1295, 2007 52. Aspenberg P, Wang JS, Jonsson K, et al: Experimental osteonecrosis of the lunate. Revascularization may cause collapse. J Hand Surg Br 19: 565-569, 1994 53. Yajima H, Ono H, Tamai S: Temporary internal fixation of the scaphotrapezio-trapezoidal joint for the treatment of Kienböck’s disease: A preliminary study. J Hand Surg Am 23:402-410, 1998
P
edicled vascularized bone grafts (VBGs) from the dorsal distal radius have been used for a variety of carpal pathologies.1-3 Use of VBGs is attractive for the potential to recolonize the host site with osteoprogenitor cells.4,5 Transplantation of viable osteocytes (greater than 90% survival for VBGs) is believed to result in an accelerated process of graft– host union through primary bone healing without resorption or creeping substitution.4-7 Additionally, the robust corticocancellous bone able to be harvested from the distal dorsal radius allows for replacement of deficient bone stock and provides structural integrity.4,5 Most importantly, dorsal distal radius VBGs have the ability to introduce, maintain, and increase (up to 4-fold) vascularity to the recipient carpal bone from the donor vascular pedicle.8 As such, dorsal distal radius pedicled VBGs are a powerful treatment option for avascular necrosis (AVN) of the carpus compared with conventional non-VBGs.9 A variety of pedicled dorsal distal radius VBGs have been described rooted on a consistent and reliable arterial network.2,3,10 Initially, Zaidemberg reported the use of a pedicled VBG from the radial styloid based on an “ascending irrigating branch” from the radial artery for the treatment scaphoid nonunion. Subsequently, an extensive cadaveric
Division of Hand Surgery, Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN. Address reprint requests to Alexander Y. Shin, MD, Division of Hand Surgery, Department of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905. E-mail: [email protected]
1048-6666/12/$-see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1053/j.oto.2012.07.003
study performed by Sheetz et al10 correctly defined this pedicle as the 1,2-intercompartmental supraretinacular artery (1,2-ICSRA)1 and detailed the pattern of extraosseous arterial blood supply to the distal radius. This provided the framework for reliable anatomic landmarks to identify and use multiple dorsal distal radius vascular pedicles for VBGs in antegrade or retrograde flow manner. When compared with volarly based VBGs, retrograde-flow dorsal distal radius VBGs are easier to harvest and result in less donor-site morbidity.11 The criteria for VBGs of the distal radius include (1) sufficient length from harvest to donor site without risk of pedicle kinking, (2) must provide nutrient vessels to both cortical and cancellous bone, and (3) provide adequate blood flow to maintain viability.12 Although pedicled dorsal distal radius VBGs can theoretically be used to address AVN of the entire carpus, they are more commonly used to address pathology of the scaphoid. Recently, the 1,2-ICSRA has gained popularity toward the treatment of scaphoid nonunions with or without AVN of the proximal pole.1,2,13-17 However, its use has been reported toward the treatment scaphoid AVN (Preiser disease).18,19 Little is known regarding the etiology of Preiser disease; however, disruption of the blood supply to the scaphoid has been heavily measured.20,21 Because of the lack of evidence-based medicine (consisting of small series and case reports), optimal treatment options are varied22-26 and based on the stage of the disease, as described by Herbert and Lanzetta.27 The use of VBGs is limited to early disease in the setting of an intact cartilaginous shell without radiocarpal or mid-carpal 151
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arthritis.18,28 A few VBGs have been described for the treatment of early Preiser disease, including a pronator pedicle,29 implantation of a vascular bundle,30,31 and dorsal distal radius VBGs with the 1,2- and 2,3-ICSRA.18,19 VBG has also gained popularity in the treatment of lunate AVN (Kienbock disease). The etiology of Kienbock disease is speculative; however, many believe that anatomic,32 vascular,21,33 and biomechanical factors (increased load transmission due to ulnar minus variance)34,35 may play a role. Nonetheless, a predictable pattern of arthritis and collapse occur.36,37 Treatment options are based on the Stahl-Lichtman classification38 and include joint-leveling procedures (ulnar lengthening or radial shortening),39,40 lateral closing wedge osteotomy,41 or partial wrist arthrodesis for early stages.42 A myriad of VBGs have been used in the setting of an intact cartilage shell without radiocarpal or midcarpal arthroses, including a pedicled vascular pisiform43,44 or scaphoid tubercle,45 pronator quadratus,29 dorsal metacarpal arteriovenous bundle implantation,31,46 and the 4th ⫹ 5th extensor carpal artery (4 ⫹ 5 ECA) VBG.3,47 Techniques for VBGs to the lunate have been varied with or without joint-leveling procedures.44
Anatomy The complex arterial network to the distal dorsal radius was elucidated by Sheetz et al.10 Four extraosseous vessels (radial, ulnar, anterior, and posterior interosseous arteries) provide nutrient vessels to the distal radius and ulna. The anterior interosseous artery divides into the anterior and posterior divisions. The latter, combined with the radial artery, represent the primary source of antegrade flow to the distal dorsal radius. Four nutrient vessels originate from these vessels, which serve as pedicles to the distal dorsal radius VBGs. They are named according to their course relative to the extensor compartments (ECAs) and retinaculum. There are two intercompartmental vessels that reside on top of the retinaculum (supraretinacular) between the named ECAs: the 1,2-ICSRA and 2,3-ICSRA. Additionally, there are two vessels that rest within the floor of their respective ECAs: the 4th and 5th ECA (Fig. 1).10 Distal to these vessels, arterial arches in series across the dorsum of the wrist serve as a distal anastomotic network for the ICSRA and ECA (dorsal intercarpal arch, dorsal radiocarpal arch, and the dorsal supraretinacular arch). The dorsal intercarpal arch plays a pivotal role connecting the ICSRAs and ECAs, which allows for distally based reversed flow VBGs after proximal ligation, and serves the basis for most of the distal dorsal radius VBGs. The major limiting factor in terms of the various distal dorsal radius VBGs is the arc of motion of each harvested graft.10 In the treatment of Preiser disease and Kienbock disease, we prefer to use the 1,2-ICSRA (Fig. 2A) and the combined 4 ⫹ 5 ECA (Fig. 2B), respectively. The 1,2-ICSRA originates from the radial artery approximately 5 cm proximal to the radiocarpal joint and travels deep to the brachioradialis, on top of the extensor retinaculum, toward the anatomic snuffbox where it joins the radial artery, and/or the radiocarpal arch. This artery is present in 94% of cadaveric spec-
Figure 1 Vascular anatomy of the dorsal distal radius. Two arteries course between the dorsal extensor compartments (ECA), the 1,2and the 2,3-intercompartmental supraretinacular artery (ICSRA), and 2 arteries travel within the ECA, the 4th and 5th ECA. These arteries can be used as pedicles for vascularized bone grafts to the scaphoid or the lunate, respectively. RA ⫽ radial artery, UA ⫽ ulnar artery, dICa ⫽ dorsal intercarpal artery, dRCa ⫽ dorsal radiocarpal artery, dSRa ⫽ dorsal supraretinacular artery, AIA ⫽ anterior interosseous artery, PIA ⫽ posterior interosseous artery, aAIA ⫽ anterior division of the anterior interosseous artery, and pAIA ⫽ posterior division of the anterior interosseous artery. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
imens, travels with two venae comitantes, provides on average 3.2 nutrient arteries, of which 6% penetrate into cancellous bone at a mean distance of 15 mm proximal to the joint line.10 With a mean internal diameter of 0.3 mm, it is the smallest of the 4 distal dorsal radius vessels. The short arc of rotation limits its use toward treatment of the scaphoid. The 4th ECA originates from the posterior division of the anterior interosseous artery and courses along the floor of the 4th ECA, adjacent to the posterior interosseous nerve. The 4th ECA has been shown to be present in 100% of cadaveric specimens. An average of 3.2 nutrient arteries are present at a mean distance of 11 mm proximal to the joint line. Up to 45% of the nutrient vessels penetrate deep into the cancellous bone.10 Conversely, the 5th ECA rarely provides nutrient vessels to the distal dorsal radius, as it travels along the radial floor of the 5th ECA. However, because of its large internal diameter (mean 0.49 mm) and multiple sites of distal anastomoses (dorsal intercarpal arch, 4th ECA, dorsal radiocarpal arch, 2,3-ICSRA, and the oblique dorsal artery of the distal ulna), it serves as an excellent conduit for retrograde flow to the 4th ECA.10,48
Dorsal distal radius pedicled vascularized bone grafting
153 (MRI) alterations involving the whole scaphoid (with the exception of the distal tubercle).25 The treatment algorithm for Preiser disease continues to be defined; however, our indications for the use of VBGs for the treatment of scaphoid AVN is restricted to early-stage disease (Herbert stage I or II, Table 1) without degenerative change at the radiocarpal or midcarpal joints, nor carpal collapse.27 We also use the system defined by Kalainov et al28 to grade the scaphoid’s avascular status as generalized (type I) or segmental vascular impairment (type II) on magnetic imaging resonance studies with intravenous gadolinium.19 In our experience, the former (generalized AVN of the scaphoid) is technically more demanding, as it is difficult to remove all necrotic bone without breeching the cartilage shell.18 Our preferred distal dorsal radius VBG is the 1,2-ICSRA, and the 2,3-ICSRA serves as a salvage.18,19 If, at the time of surgery, radiocarpal arthritis is present, then revascularization is contraindicated, and a salvage procedure, such as scaphoidectomy and four-corner arthrodesis or proximal row carpectomy, is performed.
1,2-Intercompartmental Supraretinacular Artery Graft Technique
Figure 2 Pedicled dorsal distal radius vascularized bone graft arc of rotation. (A) 1,2-intercompartmental supraretinacular artery (1,2ICSRA) and the (B) 4 ⫹ 5 ECA artery (4 ⫹ 5 ECA). (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
The technique is similar for VBG in the treatment of scaphoid nonunion.49 The patient is positioned supine with the affected extremity positioned on a hand table. After an unsterile tourniquet is applied to the upper arm, the extremity is prepped and draped. The extremity is elevated, and the tourniquet is inflated only to 200 mm Hg without exsanguination. This allows for better visualization of the donor vessels. A curvilinear (S-shaped) incision is placed over the 1st and 2nd ECA (Fig. 3A). Sharp dissection is performed, taking care to identify and protect the superficial branch of the radial nerve, down to the 1,2-ICSRA, and accompanying two vena comitantes located between the 1st and 2nd ECAs, which lie above the retinaculum (Fig. 3B). The vessel is dissected distally to its anastamoses with the radial artery. The bone graft region is centered 15 mm proximal to the radiocarpal joint to maximize retention of the nutrient vessels. The 1st and 2nd ECAs are opened, maintaining a cuff of retinacular tissue on either side of the vessels, the associated extensor tendons are retracted ulnarly and radially. The 1,2-ICSRA and veins are left adherent to the bone at the graft site, then ligated proximal to the graft site. After the retinacular tissue has been elevated in line with the graft, an osteotomy is performed with a microsagittal saw and elevated with small (2 mm) osteotomes (Fig. 4A). For distal cuts, the 1,2-ICSRA and veins are retracted radially Table 1 Stages of Preiser’s Disease: Herbert Classification
Preiser Disease (Avascular Necrosis of the Scaphoid)
Stage 1
Stage 2
Indication/Contraindication The diagnosis of Preiser disease include (1) absence of trauma and/or prior wrist procedures, (2) radiologic alteration in at least 80% of the bone, and (3) magnetic resonance imaging
Stage 3 Stage 4
Normal radiographs Positive bone scan Positive MRI finding Proximal pole increased density on radiographs Generalized osteoporosis Proximal pole fragmentation ⴞ fracture on radiographs Carpal collapse with osteoarthritis
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ternal fixation or scaphocapitate pins if a large bone defect had been encountered (Kalainov et al28 type II).19 Hemostasis is obtained, and the wound is thoroughly irrigated. The capsule does not need to be sutured back; however, this may be performed cautiously as to not cause impediment to flow through the pedicle. The incision is closed with nonabsorbable sutures. The extremity is placed into a well-padded long arm thumb spica splint with the wrist in neutral position.
Rehabilitation Range of motion exercises are allowed at the fingers and shoulder immediately. At 2 weeks postoperative, the sutures are removed, and the arm is placed into a long arm thumb spica cast for an additional 10 weeks in neutral wrist position. At the time of cast removal, radiographs are obtained to assess for fracture healing. If external fixation or pins were used, these are removed at this time as well. At 12 weeks postoperative, wrist range of motion and strengthening exercises are initiated, and the patient is gradually weaned out of the splint.
Figure 3 Surgical approach to the 1,2-intercompartmental supraretinacular artery (1,2-ICSRA) vascularized bone graft. (A) Curvilinear incision centered over the 1st and 2nd ECA. (B) Identification of the 1,2-ICSRA between the 1st and 2nd ECA. S ⫽ scaphoid, R ⫽ radius, RA ⫽ radial artery, I ⫽1st ECA, II ⫽ second ECA, III ⫽3rd ECA, SBRN ⫽ superficial branch of the radial nerve. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
and then ulnarly to protect the vessels. If desired, the tourniquet can be deflated to check for arterial perfusion. A transverse, dorsal-radial capsulotomy is made ulnar to the 1,2-ICSRA vessels to in line with of the radiotriquetral ligaments (dorsal intercarpal ligament). Up to one-half of the radiotriquetral ligament can be divided if needed to facilitate exposure of the scaphoid.49 A dorsal cortical window is prepared within the scaphoid, through which all necrotic and sclerotic bone is removed using a combination of power burr and curettes, taking care to preserve the cartilaginous shell.19 The bone graft is transplanted into the bone defect, additional distal radius bone graft can be packed into the scaphoid if needed. The inlay graft can be stabilized with Kirschner wires (K-wires) or simply press fit (Fig. 4B). It is important to take care when tamping the bone graft as to not cause direct trauma to the vessels. If early arthritic change is noted at the radiostyloid joint, then a radial styloidectomy can also be performed. Rarely, the radial styloid may need to be removed if vascular pedicle impingement is encountered. Although unloading of the scaphoid has not been shown to provide an additional benefit,19,28 we reserve the use of ex-
Figure 4 1,2-ICSRA vascularized bone graft harvest and insetting. (A) Bone graft harvest centered over the 1,2-ICSRA. (B) Insetting of the 1,2-ICSRA vascularized bone graft, initially secured with percutaneous pins fixation. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
Dorsal distal radius pedicled vascularized bone grafting Table 2 Stages of Kienbock’s Disease: Stahl-Lichtman Classification Stage 1 Normal radiographs Positive bone scan Positive MRI finding Stage 2 Lunate increased density without collapse on radiographs Stage 3 Lunate collapse with partial or complete sclerosis (a) proximal row remained aligned (b) proximal row malaligned and destabilized Stage 4 Lunate fragmentation with degenerative changes at the radiocarpal and/or midcarpal joint
155 ECA as the pedicle (4 ⫹ 5 ECA) in the treatment of Kienbock disease. This allows retrograde flow through the 5th ECA and antegrade flow to the 4th ECA by ligation of the posterior branch of the anterior interosseous artery.3 The advantages to the 4 ⫹ 5 ECA are its (1) large pedicle diameter, (2) long pedicle length, (3) and the pedicle’s ulnar location in the wrist, which decreases risk of injury to the vessels with a dorsal arthrotomy.3
Complications Potential complications include superficial branch of the radial nerve neuritis, extensor tendon laceration, iatrogenic fractures of the distal radius, or progression of scaphoid AVN and fragmentation. In a study performed by Moran et al,19 there were no complications noted in 6 patients who underwent 1,2-ICSRA for Preiser disease. Only one patient required an additional surgery (proximal row carpectomy) for continued pain, despite MRI evidence of scaphoid revascularization.
Kienbock Disease (Avascular Necrosis of the Lunate) Indication/Contraindication Historically, VBGs have been indicated in the treatment of early stage of Kienbock disease without carpal collapse (Lichtman stage I to IIIa, Table 2), particularly when joint level procedures are contraindicated (ulnaneural or positive variance). More importantly, an intact cartilage shell (without fracture or fragmentation) and without evidence of carpal arthrosis is necessary for dorsal distal radius VBG.50 Although this can be assessed with CT and MRI, if any ambiguity exists, we routinely use wrist arthroscopy (without the 4-5 or ulnar midcarpal portal to prevent injury to the 4th or 5th ECA)48 to confirm the absence of wrist arthrosis and status of the lunate articular surface. The presence of carpal collapse is not a contraindication if the integrity of the articular cartilage shell has been maintained (stage IIIb). Thus, the ideal indication is an ulnar neutral stage II-IIIa/b without fragmentation of the lunate. Revascularization is contraindicated when associated radiocarpal and midcarpal arthritis is present. Generally, VBGs should not be performed if the lunate is fractured with extrusion or if the articular cartilage shell has been breached. A relative contraindication is a history of a prior dorsal wrist procedure due to the potential for dorsal wrist arterial network disruption.50 Although the 4th ECA can be used as the pedicle, we prefer to use the 4th ECA dorsal distal radius bone graft with the 5th
Figure 5 Approach to the 4 ⫹ 5 ECA. (A) Dorsal midline approach identifying the 4th and 5th ECA. (B) Ligament-sparing dorsal wrist arthrotomy and region of bone graft harvest. ECA, extensor compartment artery. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
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4 ⴙ 5 ECA Artery Graft Technique The surgical positioning and preparation is similar to that described for the 1,2-ICSRA. The arm is not exsanguinated before tourniquet inflation to assist with vessel identification. A longitudinal incision is made in line with the 3rd metacarpal. The 5th dorsal ECA is entered, and the 5th ECA (with vena comitantes) is identified in the radial aspect of the compartment (Fig. 5A). The 5th ECA is typically adjacent to or partially within the septum, separating the 4th and 5th dorsal ECA. The vessel is traced to its origin from the anterior interosseous artery. At this confluence, the 4th ECA origin is identified, and the vessel is traced distally. A radially based extensor retinacular flap is developed from the 5th to the 2nd ECA to allow adequate exposure of the dorsal wrist capsule (Fig. 5B). A dorsal ligament-sparing capsulotomy51 is made at the radiocarpal joint to visualize the lunate (care is maintained to preserve the 5th ECA as it courses of the dorsal wrist capsule). The lunate is inspected for fragmentation, collapse, or breach of the articular shell, and the presence of arthroses. If any of these are present, attempt at revascularization is abandoned, and a salvage procedure is performed. If revascularization is still indicated, a combination of high speed burr and curettes are used to create a dorsal hole within the lunate, through which necrotic bone is removed. Fluoroscopy can be used to ensure careful curettage without chondral breach. If the articular shell has collapsed after debridement, a blunt tip spreader can be used to carefully expand the articular shell (Fig. 6). The bone graft region is marked, usually centered approximately 1.1 cm proximal to the radiocarpal joint over the 4th
ECA.48 The bone graft should be slightly larger than needed to allow for trimming and insetting. The graft’s proximal– distal length represents the depth of the excavated defect, whereas the radioulnar width indicates the anteroposterior dimension.48 The 4th and 5th ECA are elevated from the dorsal distal radius with cuff of periosteum on each end, the 4th ECA is kept intact with the corticoperiosteal surface near the bone graft site. The posterior division of the anterior interosseous artery is ligated, proximal to the 4th and 5th ECA origin. The bone graft is elevated using a microsagittal saw and thin osteotomes (Fig. 7A). The tourniquet can be deflated at this time to ensure adequate vascularity. We have now abandoned this confirmatory step, as subsequent hemorrhage adds difficulty to the remainder of the case. Additional dorsal distal radius bone graft is harvested through the donor graft bed and packed within the lunate. A central cavity is prepared for insertion of the VBG, which is inserted with the pedicle oriented vertically and the cortical surface aligned proximal to distal to serve as a strut for maintenance of lunate height during revascularization.48 The VBG can be press fit as an inlay graft; therefore, internal fixation is not necessary (Fig. 7B). Lunate is vulnerable to recurrent collapse during revascularization52 and early loading can be detrimental12,53; therefore, we temporarily pin the intercarpal joint to unload the lunate. The scaphocapitate joint is pinned with a 0.0625-inch K-wire under approximately 10 lbs of longitudinal traction. After irrigation of the wound, the donor site can be packed with cancellous allograft or calciumbased bone graft substitute. The capsule and retinaculum are repaired cautiously as to not impede or kink the pedicle. The
Figure 6 Debridement of the lunate. A dorsal cortical window is made into the lunate with a burr. After necrotic bone removal, the lunate articular cartilage shell can be gently expanded with a blunt tip spreader. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
Dorsal distal radius pedicled vascularized bone grafting
157 ECA, both were pin tract infections. Two patients required wrist arthrodesis for persistent pain.
Conclusions Many revascularization options have been described to address AVN of the carpus, specifically the scaphoid (Preiser disease) and lunate (Kienbock disease). Pedicled dorsal distal radius VBGs are advantageous because of a consistent arterial network, which allows for multiple donor options based on the location of the recipient carpal bone. Although many different VBGs have been described for the treatment of Preiser disease and Kienbock disease, we prefer to use the 1,2ICSRA and the 4 ⫹ 5 ECA, respectively.19,33
References
Figure 7 4 ⫹ 5 ECA vascularized bone graft harvest and insetting. (A) Bone graft harvest after proximal vessel ligation. (B) Insetting of the 4 ⫹ 5 ECA vascularized bone graft into the lunate. (Reprinted by permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
skin is closed with nonabsorbable suture, and the arm is placed in to a long-arm splint.
Rehabilitation Immediate motion is allowed through the fingers and the shoulder for edema control. At 2 weeks postoperative, the sutures are removed and a long arm cast is applied for an additional 4 weeks. At 6 weeks postoperative, the cast is removed, and a removable short-arm volarly based plaster splint is fabricated, which is worn full time for an additional 6-8 weeks. Supervised therapy is initiated for gentle wrist flexion and extension stretching exercises. At 12 weeks postoperative, the scaphocapitate pins are removed, and wrist strengthening exercises are started. The patient is gradually weaned out of the splint after pin removal.
Complications Potential complications include extensor tendon laceration, pin tract infections, and iatrogenic fracture through the distal radius. In a series by Moran et al,3 there were 2 complications in 26 patients with Kienbock disease treated with the 4 ⫹ 5
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