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Elbow vascularized composite allotransplantation—surgical anatomy and technique
J Shoulder Elbow Surg (2017) 26, 1325–1334
www.elsevier.com/locate/ymse
ORIGINAL ARTICLE
Elbow vascularized composite allotransplantation—surgical anatomy and technique Zvi Steinberger, MDa,b,*,1, Heng Xu, MDa,1, Nikolas H. Kazmers, MDc, Stephanie Thibaudeau, MDd, Russel G. Huffman, MDa, L. Scott Levin, MD, FACSa,e a
Department of Orthopedic Surgery, Penn Medicine University City, Philadelphia, PA, USA Department of Orthopedic Surgery, Sheba Medical Center, Tel Hashomer, Israel c Department of Orthopedics, University of Utah, Salt Lake City, UT, USA d Division of Plastic and Reconstructive Surgery, McGill University, Montreal, QC, Canada e Division of Plastic Surgery, Perelman Center for Advanced Medicine, Philadelphia, PA, USA b
Background: Elbow reconstruction with vascularized composite allotransplantation (VCA) may hold promise in treating end-stage arthritis as no current treatment is both functional and durable. We describe the vascular and gross anatomy of the elbow in the context of VCA procurement and propose a step-by-step surgical technique for human elbow VCA. Methods: We injected latex in the arterial tree of 16 fresh adult cadaveric upper extremities. We identified and measured arteries and nerves and their branch points relative to the medial epicondyle. Based on our determination of the dominant blood supply to osseous and capsular elbow structures, we derived a cadaveric model of elbow VCA by performing donor preparation on 2 fresh cadaveric upper extremities by elevating a lateral arm flap in conjunction with the vascularized elbow joint. We prepared and transplanted 2 size-matched recipient specimens to refine the surgical technique. Results: The elbow arterial supply was composed of consistent branches contributing to medial, lateral, and posterior arcades. Preservation of the elbow arterial network requires sectioning of the brachial, radial, and ulnar arteries 12 cm proximal, 1 cm distal, and 6 cm distal to the ulnar artery takeoff, respectively. The supinator, anconeus, distal brachialis, proximal aspects of the flexor digitorum profundus, and flexor carpi ulnaris must be preserved to protect osseous perforators. Articular innervation was most commonly derived from ulnar and median nerve branches. We refined our proposed surgical technique after performing 2 cadaveric elbow VCAs. Conclusions: Elbow VCA may be technically feasible on the basis of its consistent vascular anatomy and our proposed surgical technique. Level of evidence: Basic Science Study; Anatomy and Surgical Technique using Cadaver Specimens © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.
Institutional Review Board or Ethical Committee approval is not applicable. This study was approved by the anatomical gifts oversight committee. 1 These authors contributed equally to this work. *Reprint requests: Zvi Steinberger, MD, Department of Orthopedic Surgery, Penn Medicine University City, 3737 Market Street, 6th Floor, Philadelphia, PA 19104, USA. E-mail address: [email protected] (Z. Steinberger). 1058-2746/$ - see front matter © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. http://dx.doi.org/10.1016/j.jse.2017.04.014
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Keywords: End-stage elbow arthritis; vascularized composite allotransplantation; surgical anatomy; surgical steps; elbow reconstruction; cadaver
End-stage elbow arthritis is a challenging clinical entity, particularly among young patients for whom activity modification, oral anti-inflammatory medications, bracing, injection, and arthroscopic capsular releases have failed to satisfactorily relieve pain and provide function. Nonsurgical treatment options are of limited efficacy for this population of patients, and surgical treatments have significant drawbacks for active patients. After total elbow arthroplasty (TEA), lifelong limitations on weight bearing are often recommended, ranging from 5-15 pounds.21 TEA is also associated with a complication rate as high as 44%,15 and reoperation is frequently indicated.11 Relatively low 10-year TEA survival rates are a concern, ranging from 53%-81% in the nonrheumatoid population, even with newer generation implants.16,17 After interpositional arthroplasty, elbow instability12 and need for surgical revision rates of approximately 10% are known complications.8,9 Arthroscopic débridement and osteophyte excision may afford increased range of motion and short- to intermediate-term pain relief. However, durability of the procedure and associated long-term outcomes are less clear.14 Elbow arthrodesis is durable; however, the resulting loss of flexion and extension could compromise function and preclude patients from engaging in certain activities or occupations. As such, arthrodesis is most often reserved for salvage in the setting of prior failed surgical treatments. In addition, nonunion and a high rate of secondary surgery are known complications. 18 Nonvascularized, total elbow osteoarticular allografts have been used to replace the elbow for post-traumatic reconstruction or to address massive bone loss. However, half of the patients suffered a complication, and the total arc of motion was limited to 100°.4 Clearly, available surgical procedures to address end-stage elbow arthritis are limited, especially for young patients who want to remain active. Vascularized composite allotransplantation (VCA) has been successful in the context of “reconstructive transplantation” for upper extremity transradial5,19,20 and transhumeral1,20 amputees and for patients requiring facial reconstruction.7 Nonetheless, to the best of our knowledge, reconstructive transplantation of the isolated human elbow has not been reported in the medical literature. Although previous reports described the vascular and neural anatomy of the elbow after intra-arterial injection,23,24 studies attempting to elucidate a comprehensive surgical protocol to enable human elbow VCA are lacking. Such a protocol must focus on preserving the osseous and neural arterial supply. As such, reports have delineated the techniques and surgical steps needed to procure and to transplant a vascularized composite elbow allograft in a rat model.22 However, proposed techniques for elbow VCA in humans have not been reported.
This paper describes the arterial and neural anatomy of the elbow in the context of procuring a vascularized composite allograft, preparing the recipient, and transplantation. Based on preserving the arterial anatomy and bone and neural perforators, we propose a step-by-step surgical protocol for human elbow VCA.
Materials and methods Cadaveric preparation for anatomic studies This paper describes a step-by-step surgical protocol for human elbow VCA. We obtained frozen upper extremities from fresh adult human cadavers with no known history of traumatic injury or congenital abnormalities. The specimens were allowed to thaw for 24 hours at room temperature before dissection. We used 16 adult elbows to elucidate the arterial and neural anatomy of the elbow. The brachial artery was cannulated using a 16F Foley catheter, and the arterial network was injected with latex rubber (Carolina Biological Supply Company, Burlington, NC, USA) under mechanical pressure using a peristaltic electrical pump (Masterflex, L/S Economy Pump System; Metrohm Nederland, Schiedam, The Netherlands) until the dye was visualized through a minimal longitudinal incision in the long finger pulp. To allow the latex to solidify, we placed the specimens in a cold room (4°C -6°C) for 48 hours before dissection. We dissected the brachial, radial, and ulnar arteries proximal to distal to identify all branches terminating within the elbow joint capsule and surrounding osseous structures (humerus, radius, and ulna). We measured the number and location of osseous perforators with a ruler. The central portion of the medial epicondyle served as an anatomic reference point for all distance measurements. Similarly, we dissected the median, radial, and ulnar nerves proximal to distal and recorded the number and location of branches from each that penetrated the joint capsule relative to the medial epicondyle. We recorded the origin of each arterial and neural branch.
Deriving a step-by-step surgical technique for elbow VCA Using 4 additional cadaveric specimens, we performed sequential cadaveric elbow VCA procedures by procuring the donor, preparing the recipient extremity, and transplanting with osteosynthesis. The goals of the procedure were to preserve the recipient forearm, wrist, hand, and neurovascular structures while removing only the elbow joint. We used the detailed arterial and neural anatomic findings from the latex injection and dissection studies to develop a donor elbow procurement protocol that preserves the osseous perforators to the joint capsule, humerus, radius, and ulna. Furthermore, we elevated a lateral arm flap, based on the posterior radial collateral artery, along with the vascularized elbow allograft at the level of the brachial artery proximal to the posterior radial collateral artery takeoff.
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Results Arterial anatomy of the elbow The arterial supply to the elbow is composed of consistent branches contributing to medial, lateral, and posterior arcades (Fig. 1, Table I). The inferior and superior ulnar collateral arteries, along with the posterior ulnar recurrent artery, form the medial arterial arcade. The radial and middle collateral arteries, together with the radial recurrent artery, form the
lateral arterial arcade. The interosseous recurrent artery contributes to the posterior arcade of the elbow in isolation, without forming an anastomotic network. The origins of the radial collateral artery, middle collateral artery, and superior ulnar collateral artery were beyond the proximal extent of the cadaveric specimens. The inferior ulnar collateral artery originates from the brachial artery 5.6 cm proximal to the medial epicondyle (range, 5-6 cm). The anterior ulnar collateral artery and posterior ulnar recurrent artery originate from the ulnar artery 5.2 cm (range,
Figure 1 Vascular arches of the elbow. The arterial supply to the elbow was meticulously dissected after intra-arterial latex injection. (A) The medial arterial arcade of the elbow is composed of the inferior ulnar collateral artery (IUCA), superior ulnar collateral artery (SUCA), and posterior ulnar recurrent artery (PURA). For orientation purposes, left is proximal and inferior is posterior. (B) The lateral arterial arcade of the elbow is formed by the radial collateral artery (RCA), middle collateral artery (MCA), and radial recurrent artery (RRA). For orientation purposes, left is proximal and superior is posterior. (C) The posterior arterial arcade receives sole contribution from the interosseous recurrent artery (IRA). For orientation purposes, the elbow was in nearly maximal flexion. BA, brachial artery; UA, ulnar artery; RA, radial artery; Perforator A, humeral diaphyseal perforator arteries. Table I
Summary of arterial anatomic findings Origin and arcade contribution
Structures perfused
18.0-23.0
Profunda brachii—lateral
Lateral trochlea, capitellum, lateral epicondyle
18.0-23.0
Profunda brachii—lateral, posterior Brachial—medial
Capitellum, medial olecranon Olecranon fossa, medial trochlea
Brachial—medial, posterior Ulnar—none Ulnar—medial Radial—lateral Ulnar—posterior
Medial epicondyle, coronoid fossa, medial trochlea Mostly muscular (brachialis, pronator teres) Medial olecranon, medial trochlea Radial head/neck, capitellum Lateral olecranon, radial neck, capitellum
Blood supply
Location of perforator (cm from medial epicondyle) Average
Range
Radial collateral artery
Inferior ulnar collateral artery
>15* 19.9† >15* 19.9† >15* 17.2† 5.6
Anterior ulnar recurrent artery Posterior ulnar recurrent artery Recurrent radial artery Recurrent interosseous artery
5.2 5.8 4.1 9.1
4.2-6.0 5.0-6.5 3.3-5.5 8.5-10.0
Middle collateral artery Superior ulnar collateral artery
13.5-23.0 5.0-6.0
* Proximal to proximal extent of the cadaveric specimens. † Based on past literature (Yamaguchi et al24).
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Z. Steinberger et al. Summary of neural anatomic findings
Nerve supply Median Ulnar Radial Posterior interosseous Anterior interosseous
Branch points relative to medial epicondyle (cm)
No. of branches
Average
Range
Average
Range
2.7 distal 0.5 proximal 1.0 distal 8.1 distal 7.6 distal
4.5 proximal–5.0 distal 3.0 proximal–2.5 distal 1.5 proximal–5.0 distal 6.5 distal–9.0 distal 6.0 distal–9.0 distal
2.1 3.5 2.3 1.8 2.3
0-5 2-5 0-3 0-3 0-5
4.2-6 cm) and 5.8 cm (range, 5-6.5 cm) distal to the medial epicondyle, respectively. The recurrent radial artery and recurrent interosseous artery originate from the radial artery 4.1 cm (range, 3.3-5.5 cm) and 9.1 cm (range, 8.5-10.0 cm) distal to the medial epicondyle, respectively. Preserving the elbow arterial anastomotic network requires sectioning of the brachial, radial, and ulnar arteries 12 cm proximal, 1 cm distal, and 6 cm distal to the ulnar artery takeoff, respectively. The supinator, anconeus, distal brachialis, proximal aspects of the flexor digitorum profundus, and flexor carpi ulnaris muscles must be preserved to protect osseous perforators.
Neural anatomy of the elbow The median nerve provided an average of 2.1 branches (range, 0-5) within the region 4.5 cm proximal to 5.0 cm distal to the medial epicondyle. The ulnar nerve provided an average of 3.5 capsular branches (range, 2-5) within the region 3.0 cm proximal and 2.5 cm distal to the medial epicondyle. The radial nerve provided 2.3 branches (range, 0-3) from the region 1.5 cm proximal to 5.0 cm distal to the medial epicondyle. The posterior interosseous nerve provided 1.8 (range, 0-3) branches ranging from 6.5 cm proximal to 9 cm distal with respect to the medial epicondyle. The anterior interosseous nerve provided 2.3 (range, 0-5) branches ranging from 6 cm proximal to 9 cm distal with respect to the medial epicondyle. Nerve branches to the joint were most commonly derived from the ulnar and median nerves. Table II summarizes the data pertaining to the neural anatomy of the elbow.
Developing step-by-step surgical techniques for elbow VCA We developed specific protocols for donor elbow allograft harvest (Table III, Figs. 2 and 3), recipient extremity preparation (Table IV, Fig. 4), and elbow vascularized allotransplantation (Table V, Fig. 5).
Discussion End-stage elbow arthritis is a challenging clinical entity, particularly for young, active patients. In this population, currently available treatment options have significant drawbacks. TEA and arthrodesis may limit weight bearing and range of motion,
respectively, to a degree that precludes certain activities and occupations. Similarly, the durability of interposition arthroplasty and arthroscopic débridement is questionable. The emerging field of VCA, also known as reconstructive transplantation, offers a relatively new treatment strategy for a variety of complex upper and lower extremity orthopedic problems. VCA shows promise as a reconstructive option for upper extremity amputees, including at transradial and transhumeral levels. Although elbow transplantation has been performed in the context of transhumeral amputees, there are no reports of isolated elbow transplantation in the medical literature. Goals after VCA may be categorized as acute, subacute, and long term. Acutely, transplant survival is critical, which depends on maintaining vascular inflow and outflow and on induction immunosuppression regimens that minimize the chance of acute rejection. Induction immunosuppressive therapy in the perioperative period often consists of higher doses and a greater number of agents than are used subsequently. Although variable, depending on VCA application and treating center, induction immunosuppression may include a steroid, tacrolimus, cyclosporine, mycophenolate mofetil, and other agents.2 In the subacute period, union of the osteosynthesis sites is imperative. Last, long-term goals include weaning or removal of immunosuppression while a rejection-free state is maintained with maximal functional recovery. Achievement of an immunologic chimeric state, by which long-term immunosuppression is no longer needed, is a research goal for human VCA. However, promising advances have been made in which chimerism was induced in a swine model reported by Leonard et al.10 Further work is required to achieve a similar state in humans after VCA. Nonetheless, long-term immunosuppression after VCA may be achieved with fewer agents than are used during induction. Depending on VCA application and center, long-term treatment may involve monotherapy, often tacrolimus or cyclosporine, after steroids and other agents have been discontinued.2 The objective of this study was to describe the arterial and neural anatomy of the elbow in the context of elbow VCA in humans and to use this knowledge to propose a human elbow VCA surgical protocol that preserves the recipient neurovascular structures, forearm, wrist, and fingers. Similar to the findings of Yamaguchi et al, we observed that the elbow is perfused by medial, lateral, and posterior arcades.24 Our observations regarding the arterial perforators that perfuse the bone structures of the elbow agree with previous
Elbow VCA—surgical anatomy and technique Table III Step No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14
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Proposed technique for donor elbow preparation and allograft harvest
Procedure Elevate a large lateral arm fasciocutaneous flap and trace the pedicle back to the brachial artery. Make a circumferential incision in the upper arm just distal to the axillary fold. Make a medial incision; elongate lateral incision proximally and distally after identification of the ulnar nerve. Elevate anterior and posterior skin flaps to midforearm level; reflect both skin flaps distally. Locate and expose the following structures just proximal to the elbow: brachial artery and veins, median nerve, radial nerve. Create proximally based fasciotendinous flaps for the flexor and extensor origins with retained attachment to medial and lateral epicondyles, respectively. Circumferentially release nerves proximally, stopping 4.5 cm proximal to the medial epicondyle. Expose brachial artery to a point 12 cm proximal to the arterial bifurcation. This will require excision of overlying flexor-pronator muscle. Preserve fasciotendinous portions of the distal biceps and triceps. Expose the superficial surfaces of the arterial bifurcation, proximal 1 cm of the radial artery, and proximal 6 cm of the ulnar artery—do not dissect circumferentially to preserve the deep blood supply. Expose the superficial aspect of the median, ulnar, and radial nerves for 9 cm proximal to the medial epicondyle (avoid circumferential dissection). To protect osseous perforators, preserve supinator, anconeus, proximal portion of FDP, FCU, and distal aspect of brachialis muscle. Remove remaining superficial muscle. Location of arterial sectioning relative to the ulnar artery takeoff from the brachial artery: brachial artery 12 cm proximally, radial artery 1 cm distally, ulnar artery 6 cm distally. Level of nerve (ulnar, median, radial/PIN) sectioning with respect to the medial epicondyle: 4.5 cm proximally, 9.0 cm distally. Level and order of osseous section in respect to the medial epicondyle: radius 9 cm distally, ulna 10 cm distally, humerus 9 cm proximally.
FDP, flexor digitorum profundus; FCU, flexor carpi ulnaris; PIN, posterior interosseous nerve.
reports.23,24However, our study adds critical information about muscles that must be preserved to protect these perforators. This information is crucial in devising a surgical protocol for elbow VCA. Furthermore, the muscles requiring preservation (supinator, anconeus, distal brachialis, proximal aspects of the
Table IV Step No. 1 2 3 4 5 6 7 8 9 10 11 12
flexor digitorum profundus, and flexor carpi ulnaris) serve as readily identifiable intraoperative landmarks. In addition, our proposed locations for osteotomies vary slightly from those of Wavreille et al, who suggested humerus and forearm cuts 10 cm proximal and 9 cm distal to the medial epicondyle.23
Proposed technique for recipient elbow preparation
Procedure Posterior approach: incise triceps fascia at midline, extend laterally about the olecranon tip, and continue distally along the ulna subcutaneous border. Identify and release the ulnar nerve (at least 4.5 cm proximal to 9.0 cm distal from the medial epicondyle). Incise along the medial and lateral borders of the triceps tendon and split it longitudinally along the midline. Sharply transect it at the olecranon insertion to raise medial and lateral musculotendinous flaps to expose the posterior humerus. Release the common flexor origin off of the medial epicondyle. Through the medial aspect of the posterior approach, locate and release the median nerve and brachial artery for a distance of 12 cm proximal to the medial epicondyle. Articular branches may be ligated. Through the lateral aspect of the posterior approach, locate and release the radial nerve 4.5 cm proximal to the medial epicondyle. Transversely section the humerus 9 cm proximal to the medial epicondyle with a reciprocating saw. Reflect the arm proximally through the osteotomized humerus to gain exposure to the anterior structures. Isolate and release the distal part of ulnar, radial, and median nerves. Expose the posterior interosseous nerve and release the radial tunnel to free it from the radius bone. Isolate and release the proximal portion of radial and ulnar arteries; ligate branches to the elbow joint in the extension of 1 cm and 6 cm distally in respect to the arterial bifurcation, respectively. Release the distal biceps insertion from the radial tuberosity. Osteotomize the radius 8 cm distal and the ulna 10 cm distal to the medial epicondyle and remove the recipient elbow.
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Figure 2 Donor allograft preparation with lateral arm flap (LAF) elevation. A left-sided donor was chosen. (A) Extensile incisions were drawn out. One incision was planned laterally over the upper arm to incorporate a lateral arm flap, which transitioned into a dorsal-ulnar forearm incision. The second incision, which cannot be seen in the diagram, incorporates a medial upper arm incision (similar to a cubital tunnel release incision) that transitions into a volar Henry forearm incision. Serving as the most proximal extent of dissection, a circumferential incision is made in the upper arm immediately distal to the axillary fold. The median and ulnar nerves and brachial artery are identified proximally through the medial upper arm incision. (B) Lateral arm flap elevation commences with the posterior incision. This is taken down through skin, subcutaneous tissue, and triceps fascia. The fascia is swept anteriorly to identify the lateral intermuscular septum and the posterior radial collateral artery (PRCA) flap pedicle within. (C) After completion of the proximal incision, the anterior incision for the lateral arm flap is created down to and through the underlying fascia. The lateral intermuscular septum is taken carefully off the humerus, with care taken to protect the pedicle and posterior cutaneous nerve of the arm (PCNA). The artery and nerve were traced back to the spiral groove of the humerus. The neurovascular pedicle is traced proximally to the profunda brachii, then to the brachial artery and vein proper. Similarly, the PCNA is dissected retrograde to its takeoff from the radial nerve proper. (D) Full-thickness posterior and anterior skin flaps are elevated suprafascially. The skin flaps are reflected distally. (E) The proximal aspects of the brachial artery (BA), ulnar nerve (UN), median nerve (MN), and radial nerve (RN) are identified. These structures are dissected antegrade to a level approximately 5 cm proximal to the elbow articulation. The musculotendinous and tendinous portion of the biceps brachii is identified. (F) After dissection at the level of the midforearm, the ulnar nerve, median nerve, anterior interosseous nerve, posterior interosseous nerve, and radial and ulnar arteries and veins are identified. This dissection is performed 12 cm proximal to the elbow articulation. Fasciotendinous flaps are created for the common flexor and extensor origins and for the triceps (not pictured) and distal biceps insertions, which are denuded of adherent muscle. To protect the osseous perforators, the supinator, anconeus, proximal portions of the flexor digitorum profundus and flexor carpi ulnaris, and distal brachialis muscle must be preserved. All other superficial muscles are removed.
We found that a humerus cut 9 cm proximal to the medial epicondyle would safely preserve the vascular supply yet remain amenable to 90°-90° plating, and staggering the radius and ulnar osteotomies (8 cm and 10 cm distal to the medial epicondyle, respectively) would potentially reduce the chance of radioulnar synostosis. Last, this study elaborates on our anatomic knowledge of elbow innervation. Depending on the clinical scenario, our findings allow vascularized nerve grafts to be elevated with the flap, if needed. When taken together, our current work and the previous vascular anatomic studies by Yamaguchi et al,24 Wavreille et al,23 and Koslowsky et al6 allow comprehensive understanding of the arterial and neural anatomy of the elbow in the context of human elbow VCA. In our proposed model, we used the lateral arm flap as a living monitor of perfusion and rejection of the transplanted elbow composite allograft. This “skin buoy” allows
serial flap monitoring, which is important in considering the correlation between rejection signs in the sentinel skin graft and the articular cartilage after human knee VCA.3 In addition, the lateral arm flap could be excised once it is no longer required for allograft monitoring and once postoperative swelling subsides to allow closure without a flap, noting that the subcutaneous lymphoid tissue is highly immunogenic. Nonetheless, postoperative immunosuppression remains a clinical challenge for VCA patients as it is difficult to balance the toxicity of these medications with the need to prevent acute rejection and allograft vasculopathy, which may lead to loss of the allograft. Ohno et al13 described a novel method for maintaining allograft survival after immunosuppression withdrawal in a rat vascularized femoral allotransplantation model, implanting a host-derived saphenous arteriovenous bundle into the femoral allograft. This permitted neoangiogenic hostderived circulation to develop while short-term FK506
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Figure 3 Harvested elbow vascularized composite allograft. Pictured are an anterior view (A) and posterior view (B) of the elbow vascularized allograft after sectioning of the neurovascular structures and osteotomies of the humerus, radius, and ulna. Specifically, the brachial artery (BA) and vein are resected 12 cm proximal to the medial epicondyle, which is proximal to the takeoff of the profunda brachii artery that nourishes the lateral arm flap (LAF). The radial (RA) and ulnar (UA) arteries are sectioned 1 cm and 6 cm distal to the medial epicondyle, respectively. Neural structures are sectioned 4.5 cm proximal to the medial epicondyle and 9 cm distally—the structures are found proximally and distally, but neurolysis at the level of the elbow is avoided to preserve their blood supply (vasa nervorum). Osteotomies are performed for the humerus 9 cm proximal to the medial epicondyle and 8 cm and 10 cm distal to the medial epicondyle for the radius and ulna, respectively. UN, ulnar nerve; MN, median nerve; RN, radial nerve.
(tacrolimus) immunosuppression was administered to maintain allograft blood flow and viability. After withdrawal of immunosuppression, the neoangiogenesis from the arteriovenous bundle maintained measurable blood flow and tissue viability despite vascular pedicle thrombosis.13 Despite these exciting research advances for postoperative VCA immunomodulation in animal models, applicability to human patients remains to be determined. Similarly, the success of elbow VCA in animal models is encouraging. In the context of our group’s rat elbow VCA model, we showed that cyclosporine treatment enabled full recovery of elbow motion (90 days postoperatively).22 No elbow joint rigidity was noted throughout the experimental time course, and all other upper extremity joints regained full motion. Allotransplanted rats used their forelimb for
activities of daily living and were able to achieve normal quadrupedal ambulation. However, applicability to human patients is unclear.
Conclusion This study provides insights into the arterial and neural anatomy of the elbow in the context of VCA allograft harvest, recipient preparation, and transplantation. Elbow VCA may be technically feasible on the basis of the proposed surgical steps that preserve its vascular anatomy. Future studies evaluating elbow perfusion after cadaveric transplantation with formal microvascular anastomoses could be revealing.
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Figure 4 Recipient elbow preparation. (A) An extensile posterior incision is carried out for the left upper extremity recipient. (B) As extrafascial skin flaps are elevated, the ulnar nerve (UN) is found medially within the cubital tunnel and is decompressed. The triceps tendon is split longitudinally down its midline, and its insertion is taken sharply off of the olecranon, as distal as possible. The medial and lateral triceps tendon flaps are reflected proximally to expose the posterior surface of the humerus. (C) The ulnar nerve is neurolysed from 4.5 cm proximal to 9 cm distal to the medial epicondyle and is then transposed anteriorly. The flexor origin is taken sharply off of bone and reflected distally. (D) The median nerve (MN) and brachial artery (BA) and vein are identified anterior to the flexor-pronator mass and are dissected for a distance of 4.5 cm proximally and 12.0 cm distally to the elbow joint (the distal continuations of the radial and ulnar arteries were dissected free 1 cm and 6 cm distal to the brachial artery bifurcation, respectively). The ulnohumeral (UH) joint is visible, and care was taken to avoid taking joint capsule and synovium with the flexor pronator mass flap. (E) After lateral dissection along the posterior-distal humerus, the radial nerve (RN) is identified as it travels from posterior to anterior through the lateral intermuscular septum. The radial nerve is dissected distally, with care taken to preserve the superficial radial nerve and posterior interosseous nerve (PIN) distally. The radial tunnel is decompressed to free up the PIN. The common extensor tendon is taken sharply off of the distal humerus, and this is reflected distally. Joint capsule and synovium are excised from the common extensor tendon flap, and the radial head (RH) and radial shaft are then exposed. (F) Appearance of the recipient site after osteotomies are performed and the bony elbow has been removed. The transverse humeral osteotomy is created 9 cm proximal to the medial epicondyle, and the radius and ulna are osteotomized transversely 8 cm and 10 cm distal to the medial epicondyle, respectively. The distal biceps (DB) tendon is visible after sharp excision off of the radial tuberosity.
Table V Step No. 1 2 3 4 5 6 7 8 9 10 11
Proposed technique for elbow vascularized composite allograft transplantation
Procedure Place the donor elbow into the recipient site. Perform osteosynthesis of the radius and ulna with lateral and posteromedial 3.5-mm nonlocking plates, respectively. The recipient forearm and donor radius should be placed in full supination before plating. Perform end-to-side microanastomosis of the donor and recipient radial, ulnar, and median nerves proximally to the elbow joint. Anteriorly transpose the ulnar nerve in the subcutaneous tissue. Suture the biceps tendon stump of the donor to the recipient tendon while preserving natural length of the musculotendinous unit. Reduce the humerus diaphysis and provisionally fix with a heavy K-wire placed laterally. Perform 90°-90° plate osteosynthesis of the humerus (4.5-mm posterior and 3.5-mm lateral plates). Through the medial aspect of the posterior incision, perform end-to-side microvascular anastomosis of the donor brachial artery and recipient brachial artery as proximally as possible. Suture the matching parts of the common flexor and extensor tendons while preserving natural length of the musculotendinous unit. Suture the triceps tendon donor stump to the recipient triceps tendon while preserving natural length of the musculotendinous unit. Ensure that the pedicle is not twisted and kinked, then inset the lateral arm flap within the proximal part of the posterior incision. Close the remaining wound.
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Figure 5 Proposed protocol for elbow allotransplantation. (A) The elbow vascularized composite allograft is introduced into the recipient site, the recipient forearm and donor radius are fully supinated, and osteosynthesis of the ulna is performed with a 3.5-mm nonlocking plate placed posteromedially. (B) Osteosynthesis of the radius is performed for a 3.5-mm nonlocking plate placed laterally. Both the radius and ulna are plated in compression mode. (C) End-to-side neurorrhaphy of the radial, ulnar, and median nerves is performed proximally to the elbow joint to provide proprioceptive input for the allograft. The ulnar nerve is anteriorly transposed into the subcutaneous tissue. The donor biceps and triceps tendon stumps are sutured to the recipient tendon while preserving the natural length of the musculotendinous units. (D) The donor and recipient humeri are reduced and plated with a 90°-90° construct using 4.5-mm posterior and 3.5-mm lateral nonlocking plates in compression mode. (E) End-to-side microvascular anastomosis is performed for the brachial artery and vein through the medial window. (F, G) Common extensor and flexor tendon flaps of the donor are sutured to the recipient while preserving the natural musculotendinous unit length. (H) After ensuring that the lateral arm flap pedicle is not twisted or kinked, the flap is inset within the posterior aspect of the recipient upper arm incision. The remaining wound is closed.
Disclaimer Supported by Hans Jorg Wyss foundation. The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
References 1. Cavadas PC, Ibáñez J, Thione A, Alfaro L. Bilateral trans-humeral arm transplantation: result at 2 years. Am J Transplant 2011;11:1085-90. http://dx.doi.org/10.1111/j.1600-6143.2011.03503.x 2. Diaz-Siso JR, Bueno EM, Sisk GC, Marty FM, Pomahac B, Tullius SG. Vascularized composite tissue allotransplantation—state of the art. Clin Transplant 2013;27:330-7. http://dx.doi.org/10.1111/ctr.12117 3. Diefenbeck M, Nerlich A, Schneeberger S, Wagner F, Hofmann GO. Allograft vasculopathy after allogeneic vascularized knee transplantation. Transpl Int 2011;24:e1-5. http://dx.doi.org/10.1111/j.1432-2277 .2010.01178.x 4. Ehsan A, Lee B, Itamura JM. Total elbow allografts with collateral ligament reconstruction for posttraumatic elbow injuries. J Orthop Sci 2010;15:795-803. http://dx.doi.org/10.1007/s00776-010-1540-7
5. Haddock NT, Chang B, Bozentka DJ, Steinberg DR, Levin LS. Technical implications in proximal forearm transplantation. Tech Hand Up Extrem Surg 2013;17:228-31. http://dx.doi.org/10.1097/BTH.0000000000000025 6. Koslowsky TC, Berger V, Hopf JC, Muller LP. Presentation of the vascular supply of the proximal ulna using a sequential plastination technique. Surg Radiol Anat 2015;37:749-55. http://dx.doi.org/10.1007/ s00276-015-1476-x 7. Lantieri L, Grimbert P, Ortonne N, Suberbielle C, Bories D, Gil-Vernet S, et al. Face transplant: long-term follow-up and results of a prospective open study. Lancet 2016;388:1398-407. http://dx.doi.org/10.1016/ S0140-6736(16)31138-2 8. Larson AN, Adams RA, Morrey BF. Revision interposition arthroplasty of the elbow. J Bone Joint Surg Br 2010;92:1273-7. http://dx.doi.org/ 10.1302/0301-620X.92B9.24039 9. Larson AN, Morrey BF. Interposition arthroplasty with an Achilles tendon allograft as a salvage procedure for the elbow. J Bone Joint Surg Am 2008;90:2714-23. http://dx.doi.org/10.2106/JBJS.G.00768 10. Leonard DA, Kurtz JM, Mallard C, Albritton A, Duran-Struuck R, Farkash EA, et al. Vascularized composite allograft tolerance across MHC barriers in a large animal model. Am J Transplant 2014;14:343-55. http://dx.doi.org/10.1111/ajt.12560 11. Lovy AJ, Keswani A, Dowdell J, Koehler S, Kim J, Hausman MR. Outcomes, complications, utilization trends, and risk factors for primary and revision total elbow replacement. J Shoulder Elbow Surg 2016;25:1020-6. http://dx.doi.org/10.1016/j.jse.2015.12.012 12. Nolla J, Ring D, Lozano-Calderon S, Jupiter JB. Interposition arthroplasty of the elbow with hinged external fixation for post-traumatic arthritis. J Shoulder Elbow Surg 2008;17:459-64. http://dx.doi.org/10.1016/ j.jse.2007.11.008
1334 13. Ohno T, Pelzer M, Larsen M, Friedrich PF, Bishop AT. Host-derived angiogenesis maintains bone blood flow after withdrawal of immunosuppression. Microsurgery 2007;27:657-63. http://dx.doi.org/ 10.1002/micr.20427 14. Papatheodorou LK, Baratz ME, Sotereanos DG. Elbow arthritis: current concepts. J Hand Surg Am 2013;38:605-13. http://dx.doi.org/10.1016/ j.jhsa.2012.12.037 15. Park SE, Kim JY, Cho SW, Rhee SK, Kwon SY. Complications and revision rate compared by type of total elbow arthroplasty. J Shoulder Elbow Surg 2013;22:1121-7. http://dx.doi.org/10.1016/j.jse.2013.03.003 16. Plaschke HC, Thillemann TM, Brorson S, Olsen BS. Implant survival after total elbow arthroplasty: a retrospective study of 324 procedures performed from 1980 to 2008. J Shoulder Elbow Surg 2014;23:829-36. http://dx.doi.org/10.1016/j.jse.2014.02.001 17. Prasad N, Ali A, Stanley D. Total elbow arthroplasty for non-rheumatoid patients with a fracture of the distal humerus: a minimum ten-year follow-up. Bone Joint J 2016;98-B:381-6. http://dx.doi.org/10.1302/ 0301-620X.98B3.35508 18. Reichel LM, Wiater BP, Friedrich J, Hanel DP. Arthrodesis of the elbow. Hand Clin 2011;27:179-86, vi. http://dx.doi.org/10.1016/j.hcl.2011.02.002
Z. Steinberger et al. 19. Shores JT, Brandacher G, Lee WP. Hand and upper extremity transplantation: an update of outcomes in the worldwide experience. Plast Reconstr Surg 2015;135:351e-60e. http://dx.doi.org/10.1097/PRS .0000000000000892 20. Shores JT, Higgins JP, Lee WP. Above-elbow (supracondylar) arm transplantation: clinical considerations and surgical technique. Tech Hand Up Extrem Surg 2013;17:221-7. http://dx.doi.org/10.1097/BTH .0000000000000026 21. Szekeres M, King GJ. Total elbow arthroplasty. J Hand Ther 2006;19:245-53. http://dx.doi.org/10.1197/j.jht.2006.02.010 22. Tang J, Zhu H, Luo X, Li Q, Levin LS, Tintle SM. A vascularized elbow allotransplantation model in the rat. J Shoulder Elbow Surg 2015;24:77986. http://dx.doi.org/10.1016/j.jse.2015.01.006 23. Wavreille G, Dos Remedios C, Chantelot C, Limousin M, Fontaine C. Anatomic bases of vascularized elbow joint harvesting to achieve vascularized allograft. Surg Radiol Anat 2006;28:498-510. http:// dx.doi.org/10.1007/s00276-006-0130-z 24. Yamaguchi K, Sweet FA, Bindra R, Morrey BF, Gelberman RH. The extraosseous and intraosseous arterial anatomy of the adult elbow. J Bone Joint Surg Am 1997;79:1653-62.
www.elsevier.com/locate/ymse
ORIGINAL ARTICLE
Elbow vascularized composite allotransplantation—surgical anatomy and technique Zvi Steinberger, MDa,b,*,1, Heng Xu, MDa,1, Nikolas H. Kazmers, MDc, Stephanie Thibaudeau, MDd, Russel G. Huffman, MDa, L. Scott Levin, MD, FACSa,e a
Department of Orthopedic Surgery, Penn Medicine University City, Philadelphia, PA, USA Department of Orthopedic Surgery, Sheba Medical Center, Tel Hashomer, Israel c Department of Orthopedics, University of Utah, Salt Lake City, UT, USA d Division of Plastic and Reconstructive Surgery, McGill University, Montreal, QC, Canada e Division of Plastic Surgery, Perelman Center for Advanced Medicine, Philadelphia, PA, USA b
Background: Elbow reconstruction with vascularized composite allotransplantation (VCA) may hold promise in treating end-stage arthritis as no current treatment is both functional and durable. We describe the vascular and gross anatomy of the elbow in the context of VCA procurement and propose a step-by-step surgical technique for human elbow VCA. Methods: We injected latex in the arterial tree of 16 fresh adult cadaveric upper extremities. We identified and measured arteries and nerves and their branch points relative to the medial epicondyle. Based on our determination of the dominant blood supply to osseous and capsular elbow structures, we derived a cadaveric model of elbow VCA by performing donor preparation on 2 fresh cadaveric upper extremities by elevating a lateral arm flap in conjunction with the vascularized elbow joint. We prepared and transplanted 2 size-matched recipient specimens to refine the surgical technique. Results: The elbow arterial supply was composed of consistent branches contributing to medial, lateral, and posterior arcades. Preservation of the elbow arterial network requires sectioning of the brachial, radial, and ulnar arteries 12 cm proximal, 1 cm distal, and 6 cm distal to the ulnar artery takeoff, respectively. The supinator, anconeus, distal brachialis, proximal aspects of the flexor digitorum profundus, and flexor carpi ulnaris must be preserved to protect osseous perforators. Articular innervation was most commonly derived from ulnar and median nerve branches. We refined our proposed surgical technique after performing 2 cadaveric elbow VCAs. Conclusions: Elbow VCA may be technically feasible on the basis of its consistent vascular anatomy and our proposed surgical technique. Level of evidence: Basic Science Study; Anatomy and Surgical Technique using Cadaver Specimens © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.
Institutional Review Board or Ethical Committee approval is not applicable. This study was approved by the anatomical gifts oversight committee. 1 These authors contributed equally to this work. *Reprint requests: Zvi Steinberger, MD, Department of Orthopedic Surgery, Penn Medicine University City, 3737 Market Street, 6th Floor, Philadelphia, PA 19104, USA. E-mail address: [email protected] (Z. Steinberger). 1058-2746/$ - see front matter © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. http://dx.doi.org/10.1016/j.jse.2017.04.014
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Keywords: End-stage elbow arthritis; vascularized composite allotransplantation; surgical anatomy; surgical steps; elbow reconstruction; cadaver
End-stage elbow arthritis is a challenging clinical entity, particularly among young patients for whom activity modification, oral anti-inflammatory medications, bracing, injection, and arthroscopic capsular releases have failed to satisfactorily relieve pain and provide function. Nonsurgical treatment options are of limited efficacy for this population of patients, and surgical treatments have significant drawbacks for active patients. After total elbow arthroplasty (TEA), lifelong limitations on weight bearing are often recommended, ranging from 5-15 pounds.21 TEA is also associated with a complication rate as high as 44%,15 and reoperation is frequently indicated.11 Relatively low 10-year TEA survival rates are a concern, ranging from 53%-81% in the nonrheumatoid population, even with newer generation implants.16,17 After interpositional arthroplasty, elbow instability12 and need for surgical revision rates of approximately 10% are known complications.8,9 Arthroscopic débridement and osteophyte excision may afford increased range of motion and short- to intermediate-term pain relief. However, durability of the procedure and associated long-term outcomes are less clear.14 Elbow arthrodesis is durable; however, the resulting loss of flexion and extension could compromise function and preclude patients from engaging in certain activities or occupations. As such, arthrodesis is most often reserved for salvage in the setting of prior failed surgical treatments. In addition, nonunion and a high rate of secondary surgery are known complications. 18 Nonvascularized, total elbow osteoarticular allografts have been used to replace the elbow for post-traumatic reconstruction or to address massive bone loss. However, half of the patients suffered a complication, and the total arc of motion was limited to 100°.4 Clearly, available surgical procedures to address end-stage elbow arthritis are limited, especially for young patients who want to remain active. Vascularized composite allotransplantation (VCA) has been successful in the context of “reconstructive transplantation” for upper extremity transradial5,19,20 and transhumeral1,20 amputees and for patients requiring facial reconstruction.7 Nonetheless, to the best of our knowledge, reconstructive transplantation of the isolated human elbow has not been reported in the medical literature. Although previous reports described the vascular and neural anatomy of the elbow after intra-arterial injection,23,24 studies attempting to elucidate a comprehensive surgical protocol to enable human elbow VCA are lacking. Such a protocol must focus on preserving the osseous and neural arterial supply. As such, reports have delineated the techniques and surgical steps needed to procure and to transplant a vascularized composite elbow allograft in a rat model.22 However, proposed techniques for elbow VCA in humans have not been reported.
This paper describes the arterial and neural anatomy of the elbow in the context of procuring a vascularized composite allograft, preparing the recipient, and transplantation. Based on preserving the arterial anatomy and bone and neural perforators, we propose a step-by-step surgical protocol for human elbow VCA.
Materials and methods Cadaveric preparation for anatomic studies This paper describes a step-by-step surgical protocol for human elbow VCA. We obtained frozen upper extremities from fresh adult human cadavers with no known history of traumatic injury or congenital abnormalities. The specimens were allowed to thaw for 24 hours at room temperature before dissection. We used 16 adult elbows to elucidate the arterial and neural anatomy of the elbow. The brachial artery was cannulated using a 16F Foley catheter, and the arterial network was injected with latex rubber (Carolina Biological Supply Company, Burlington, NC, USA) under mechanical pressure using a peristaltic electrical pump (Masterflex, L/S Economy Pump System; Metrohm Nederland, Schiedam, The Netherlands) until the dye was visualized through a minimal longitudinal incision in the long finger pulp. To allow the latex to solidify, we placed the specimens in a cold room (4°C -6°C) for 48 hours before dissection. We dissected the brachial, radial, and ulnar arteries proximal to distal to identify all branches terminating within the elbow joint capsule and surrounding osseous structures (humerus, radius, and ulna). We measured the number and location of osseous perforators with a ruler. The central portion of the medial epicondyle served as an anatomic reference point for all distance measurements. Similarly, we dissected the median, radial, and ulnar nerves proximal to distal and recorded the number and location of branches from each that penetrated the joint capsule relative to the medial epicondyle. We recorded the origin of each arterial and neural branch.
Deriving a step-by-step surgical technique for elbow VCA Using 4 additional cadaveric specimens, we performed sequential cadaveric elbow VCA procedures by procuring the donor, preparing the recipient extremity, and transplanting with osteosynthesis. The goals of the procedure were to preserve the recipient forearm, wrist, hand, and neurovascular structures while removing only the elbow joint. We used the detailed arterial and neural anatomic findings from the latex injection and dissection studies to develop a donor elbow procurement protocol that preserves the osseous perforators to the joint capsule, humerus, radius, and ulna. Furthermore, we elevated a lateral arm flap, based on the posterior radial collateral artery, along with the vascularized elbow allograft at the level of the brachial artery proximal to the posterior radial collateral artery takeoff.
Elbow VCA—surgical anatomy and technique
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Results Arterial anatomy of the elbow The arterial supply to the elbow is composed of consistent branches contributing to medial, lateral, and posterior arcades (Fig. 1, Table I). The inferior and superior ulnar collateral arteries, along with the posterior ulnar recurrent artery, form the medial arterial arcade. The radial and middle collateral arteries, together with the radial recurrent artery, form the
lateral arterial arcade. The interosseous recurrent artery contributes to the posterior arcade of the elbow in isolation, without forming an anastomotic network. The origins of the radial collateral artery, middle collateral artery, and superior ulnar collateral artery were beyond the proximal extent of the cadaveric specimens. The inferior ulnar collateral artery originates from the brachial artery 5.6 cm proximal to the medial epicondyle (range, 5-6 cm). The anterior ulnar collateral artery and posterior ulnar recurrent artery originate from the ulnar artery 5.2 cm (range,
Figure 1 Vascular arches of the elbow. The arterial supply to the elbow was meticulously dissected after intra-arterial latex injection. (A) The medial arterial arcade of the elbow is composed of the inferior ulnar collateral artery (IUCA), superior ulnar collateral artery (SUCA), and posterior ulnar recurrent artery (PURA). For orientation purposes, left is proximal and inferior is posterior. (B) The lateral arterial arcade of the elbow is formed by the radial collateral artery (RCA), middle collateral artery (MCA), and radial recurrent artery (RRA). For orientation purposes, left is proximal and superior is posterior. (C) The posterior arterial arcade receives sole contribution from the interosseous recurrent artery (IRA). For orientation purposes, the elbow was in nearly maximal flexion. BA, brachial artery; UA, ulnar artery; RA, radial artery; Perforator A, humeral diaphyseal perforator arteries. Table I
Summary of arterial anatomic findings Origin and arcade contribution
Structures perfused
18.0-23.0
Profunda brachii—lateral
Lateral trochlea, capitellum, lateral epicondyle
18.0-23.0
Profunda brachii—lateral, posterior Brachial—medial
Capitellum, medial olecranon Olecranon fossa, medial trochlea
Brachial—medial, posterior Ulnar—none Ulnar—medial Radial—lateral Ulnar—posterior
Medial epicondyle, coronoid fossa, medial trochlea Mostly muscular (brachialis, pronator teres) Medial olecranon, medial trochlea Radial head/neck, capitellum Lateral olecranon, radial neck, capitellum
Blood supply
Location of perforator (cm from medial epicondyle) Average
Range
Radial collateral artery
Inferior ulnar collateral artery
>15* 19.9† >15* 19.9† >15* 17.2† 5.6
Anterior ulnar recurrent artery Posterior ulnar recurrent artery Recurrent radial artery Recurrent interosseous artery
5.2 5.8 4.1 9.1
4.2-6.0 5.0-6.5 3.3-5.5 8.5-10.0
Middle collateral artery Superior ulnar collateral artery
13.5-23.0 5.0-6.0
* Proximal to proximal extent of the cadaveric specimens. † Based on past literature (Yamaguchi et al24).
1328 Table II
Z. Steinberger et al. Summary of neural anatomic findings
Nerve supply Median Ulnar Radial Posterior interosseous Anterior interosseous
Branch points relative to medial epicondyle (cm)
No. of branches
Average
Range
Average
Range
2.7 distal 0.5 proximal 1.0 distal 8.1 distal 7.6 distal
4.5 proximal–5.0 distal 3.0 proximal–2.5 distal 1.5 proximal–5.0 distal 6.5 distal–9.0 distal 6.0 distal–9.0 distal
2.1 3.5 2.3 1.8 2.3
0-5 2-5 0-3 0-3 0-5
4.2-6 cm) and 5.8 cm (range, 5-6.5 cm) distal to the medial epicondyle, respectively. The recurrent radial artery and recurrent interosseous artery originate from the radial artery 4.1 cm (range, 3.3-5.5 cm) and 9.1 cm (range, 8.5-10.0 cm) distal to the medial epicondyle, respectively. Preserving the elbow arterial anastomotic network requires sectioning of the brachial, radial, and ulnar arteries 12 cm proximal, 1 cm distal, and 6 cm distal to the ulnar artery takeoff, respectively. The supinator, anconeus, distal brachialis, proximal aspects of the flexor digitorum profundus, and flexor carpi ulnaris muscles must be preserved to protect osseous perforators.
Neural anatomy of the elbow The median nerve provided an average of 2.1 branches (range, 0-5) within the region 4.5 cm proximal to 5.0 cm distal to the medial epicondyle. The ulnar nerve provided an average of 3.5 capsular branches (range, 2-5) within the region 3.0 cm proximal and 2.5 cm distal to the medial epicondyle. The radial nerve provided 2.3 branches (range, 0-3) from the region 1.5 cm proximal to 5.0 cm distal to the medial epicondyle. The posterior interosseous nerve provided 1.8 (range, 0-3) branches ranging from 6.5 cm proximal to 9 cm distal with respect to the medial epicondyle. The anterior interosseous nerve provided 2.3 (range, 0-5) branches ranging from 6 cm proximal to 9 cm distal with respect to the medial epicondyle. Nerve branches to the joint were most commonly derived from the ulnar and median nerves. Table II summarizes the data pertaining to the neural anatomy of the elbow.
Developing step-by-step surgical techniques for elbow VCA We developed specific protocols for donor elbow allograft harvest (Table III, Figs. 2 and 3), recipient extremity preparation (Table IV, Fig. 4), and elbow vascularized allotransplantation (Table V, Fig. 5).
Discussion End-stage elbow arthritis is a challenging clinical entity, particularly for young, active patients. In this population, currently available treatment options have significant drawbacks. TEA and arthrodesis may limit weight bearing and range of motion,
respectively, to a degree that precludes certain activities and occupations. Similarly, the durability of interposition arthroplasty and arthroscopic débridement is questionable. The emerging field of VCA, also known as reconstructive transplantation, offers a relatively new treatment strategy for a variety of complex upper and lower extremity orthopedic problems. VCA shows promise as a reconstructive option for upper extremity amputees, including at transradial and transhumeral levels. Although elbow transplantation has been performed in the context of transhumeral amputees, there are no reports of isolated elbow transplantation in the medical literature. Goals after VCA may be categorized as acute, subacute, and long term. Acutely, transplant survival is critical, which depends on maintaining vascular inflow and outflow and on induction immunosuppression regimens that minimize the chance of acute rejection. Induction immunosuppressive therapy in the perioperative period often consists of higher doses and a greater number of agents than are used subsequently. Although variable, depending on VCA application and treating center, induction immunosuppression may include a steroid, tacrolimus, cyclosporine, mycophenolate mofetil, and other agents.2 In the subacute period, union of the osteosynthesis sites is imperative. Last, long-term goals include weaning or removal of immunosuppression while a rejection-free state is maintained with maximal functional recovery. Achievement of an immunologic chimeric state, by which long-term immunosuppression is no longer needed, is a research goal for human VCA. However, promising advances have been made in which chimerism was induced in a swine model reported by Leonard et al.10 Further work is required to achieve a similar state in humans after VCA. Nonetheless, long-term immunosuppression after VCA may be achieved with fewer agents than are used during induction. Depending on VCA application and center, long-term treatment may involve monotherapy, often tacrolimus or cyclosporine, after steroids and other agents have been discontinued.2 The objective of this study was to describe the arterial and neural anatomy of the elbow in the context of elbow VCA in humans and to use this knowledge to propose a human elbow VCA surgical protocol that preserves the recipient neurovascular structures, forearm, wrist, and fingers. Similar to the findings of Yamaguchi et al, we observed that the elbow is perfused by medial, lateral, and posterior arcades.24 Our observations regarding the arterial perforators that perfuse the bone structures of the elbow agree with previous
Elbow VCA—surgical anatomy and technique Table III Step No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14
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Proposed technique for donor elbow preparation and allograft harvest
Procedure Elevate a large lateral arm fasciocutaneous flap and trace the pedicle back to the brachial artery. Make a circumferential incision in the upper arm just distal to the axillary fold. Make a medial incision; elongate lateral incision proximally and distally after identification of the ulnar nerve. Elevate anterior and posterior skin flaps to midforearm level; reflect both skin flaps distally. Locate and expose the following structures just proximal to the elbow: brachial artery and veins, median nerve, radial nerve. Create proximally based fasciotendinous flaps for the flexor and extensor origins with retained attachment to medial and lateral epicondyles, respectively. Circumferentially release nerves proximally, stopping 4.5 cm proximal to the medial epicondyle. Expose brachial artery to a point 12 cm proximal to the arterial bifurcation. This will require excision of overlying flexor-pronator muscle. Preserve fasciotendinous portions of the distal biceps and triceps. Expose the superficial surfaces of the arterial bifurcation, proximal 1 cm of the radial artery, and proximal 6 cm of the ulnar artery—do not dissect circumferentially to preserve the deep blood supply. Expose the superficial aspect of the median, ulnar, and radial nerves for 9 cm proximal to the medial epicondyle (avoid circumferential dissection). To protect osseous perforators, preserve supinator, anconeus, proximal portion of FDP, FCU, and distal aspect of brachialis muscle. Remove remaining superficial muscle. Location of arterial sectioning relative to the ulnar artery takeoff from the brachial artery: brachial artery 12 cm proximally, radial artery 1 cm distally, ulnar artery 6 cm distally. Level of nerve (ulnar, median, radial/PIN) sectioning with respect to the medial epicondyle: 4.5 cm proximally, 9.0 cm distally. Level and order of osseous section in respect to the medial epicondyle: radius 9 cm distally, ulna 10 cm distally, humerus 9 cm proximally.
FDP, flexor digitorum profundus; FCU, flexor carpi ulnaris; PIN, posterior interosseous nerve.
reports.23,24However, our study adds critical information about muscles that must be preserved to protect these perforators. This information is crucial in devising a surgical protocol for elbow VCA. Furthermore, the muscles requiring preservation (supinator, anconeus, distal brachialis, proximal aspects of the
Table IV Step No. 1 2 3 4 5 6 7 8 9 10 11 12
flexor digitorum profundus, and flexor carpi ulnaris) serve as readily identifiable intraoperative landmarks. In addition, our proposed locations for osteotomies vary slightly from those of Wavreille et al, who suggested humerus and forearm cuts 10 cm proximal and 9 cm distal to the medial epicondyle.23
Proposed technique for recipient elbow preparation
Procedure Posterior approach: incise triceps fascia at midline, extend laterally about the olecranon tip, and continue distally along the ulna subcutaneous border. Identify and release the ulnar nerve (at least 4.5 cm proximal to 9.0 cm distal from the medial epicondyle). Incise along the medial and lateral borders of the triceps tendon and split it longitudinally along the midline. Sharply transect it at the olecranon insertion to raise medial and lateral musculotendinous flaps to expose the posterior humerus. Release the common flexor origin off of the medial epicondyle. Through the medial aspect of the posterior approach, locate and release the median nerve and brachial artery for a distance of 12 cm proximal to the medial epicondyle. Articular branches may be ligated. Through the lateral aspect of the posterior approach, locate and release the radial nerve 4.5 cm proximal to the medial epicondyle. Transversely section the humerus 9 cm proximal to the medial epicondyle with a reciprocating saw. Reflect the arm proximally through the osteotomized humerus to gain exposure to the anterior structures. Isolate and release the distal part of ulnar, radial, and median nerves. Expose the posterior interosseous nerve and release the radial tunnel to free it from the radius bone. Isolate and release the proximal portion of radial and ulnar arteries; ligate branches to the elbow joint in the extension of 1 cm and 6 cm distally in respect to the arterial bifurcation, respectively. Release the distal biceps insertion from the radial tuberosity. Osteotomize the radius 8 cm distal and the ulna 10 cm distal to the medial epicondyle and remove the recipient elbow.
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Figure 2 Donor allograft preparation with lateral arm flap (LAF) elevation. A left-sided donor was chosen. (A) Extensile incisions were drawn out. One incision was planned laterally over the upper arm to incorporate a lateral arm flap, which transitioned into a dorsal-ulnar forearm incision. The second incision, which cannot be seen in the diagram, incorporates a medial upper arm incision (similar to a cubital tunnel release incision) that transitions into a volar Henry forearm incision. Serving as the most proximal extent of dissection, a circumferential incision is made in the upper arm immediately distal to the axillary fold. The median and ulnar nerves and brachial artery are identified proximally through the medial upper arm incision. (B) Lateral arm flap elevation commences with the posterior incision. This is taken down through skin, subcutaneous tissue, and triceps fascia. The fascia is swept anteriorly to identify the lateral intermuscular septum and the posterior radial collateral artery (PRCA) flap pedicle within. (C) After completion of the proximal incision, the anterior incision for the lateral arm flap is created down to and through the underlying fascia. The lateral intermuscular septum is taken carefully off the humerus, with care taken to protect the pedicle and posterior cutaneous nerve of the arm (PCNA). The artery and nerve were traced back to the spiral groove of the humerus. The neurovascular pedicle is traced proximally to the profunda brachii, then to the brachial artery and vein proper. Similarly, the PCNA is dissected retrograde to its takeoff from the radial nerve proper. (D) Full-thickness posterior and anterior skin flaps are elevated suprafascially. The skin flaps are reflected distally. (E) The proximal aspects of the brachial artery (BA), ulnar nerve (UN), median nerve (MN), and radial nerve (RN) are identified. These structures are dissected antegrade to a level approximately 5 cm proximal to the elbow articulation. The musculotendinous and tendinous portion of the biceps brachii is identified. (F) After dissection at the level of the midforearm, the ulnar nerve, median nerve, anterior interosseous nerve, posterior interosseous nerve, and radial and ulnar arteries and veins are identified. This dissection is performed 12 cm proximal to the elbow articulation. Fasciotendinous flaps are created for the common flexor and extensor origins and for the triceps (not pictured) and distal biceps insertions, which are denuded of adherent muscle. To protect the osseous perforators, the supinator, anconeus, proximal portions of the flexor digitorum profundus and flexor carpi ulnaris, and distal brachialis muscle must be preserved. All other superficial muscles are removed.
We found that a humerus cut 9 cm proximal to the medial epicondyle would safely preserve the vascular supply yet remain amenable to 90°-90° plating, and staggering the radius and ulnar osteotomies (8 cm and 10 cm distal to the medial epicondyle, respectively) would potentially reduce the chance of radioulnar synostosis. Last, this study elaborates on our anatomic knowledge of elbow innervation. Depending on the clinical scenario, our findings allow vascularized nerve grafts to be elevated with the flap, if needed. When taken together, our current work and the previous vascular anatomic studies by Yamaguchi et al,24 Wavreille et al,23 and Koslowsky et al6 allow comprehensive understanding of the arterial and neural anatomy of the elbow in the context of human elbow VCA. In our proposed model, we used the lateral arm flap as a living monitor of perfusion and rejection of the transplanted elbow composite allograft. This “skin buoy” allows
serial flap monitoring, which is important in considering the correlation between rejection signs in the sentinel skin graft and the articular cartilage after human knee VCA.3 In addition, the lateral arm flap could be excised once it is no longer required for allograft monitoring and once postoperative swelling subsides to allow closure without a flap, noting that the subcutaneous lymphoid tissue is highly immunogenic. Nonetheless, postoperative immunosuppression remains a clinical challenge for VCA patients as it is difficult to balance the toxicity of these medications with the need to prevent acute rejection and allograft vasculopathy, which may lead to loss of the allograft. Ohno et al13 described a novel method for maintaining allograft survival after immunosuppression withdrawal in a rat vascularized femoral allotransplantation model, implanting a host-derived saphenous arteriovenous bundle into the femoral allograft. This permitted neoangiogenic hostderived circulation to develop while short-term FK506
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Figure 3 Harvested elbow vascularized composite allograft. Pictured are an anterior view (A) and posterior view (B) of the elbow vascularized allograft after sectioning of the neurovascular structures and osteotomies of the humerus, radius, and ulna. Specifically, the brachial artery (BA) and vein are resected 12 cm proximal to the medial epicondyle, which is proximal to the takeoff of the profunda brachii artery that nourishes the lateral arm flap (LAF). The radial (RA) and ulnar (UA) arteries are sectioned 1 cm and 6 cm distal to the medial epicondyle, respectively. Neural structures are sectioned 4.5 cm proximal to the medial epicondyle and 9 cm distally—the structures are found proximally and distally, but neurolysis at the level of the elbow is avoided to preserve their blood supply (vasa nervorum). Osteotomies are performed for the humerus 9 cm proximal to the medial epicondyle and 8 cm and 10 cm distal to the medial epicondyle for the radius and ulna, respectively. UN, ulnar nerve; MN, median nerve; RN, radial nerve.
(tacrolimus) immunosuppression was administered to maintain allograft blood flow and viability. After withdrawal of immunosuppression, the neoangiogenesis from the arteriovenous bundle maintained measurable blood flow and tissue viability despite vascular pedicle thrombosis.13 Despite these exciting research advances for postoperative VCA immunomodulation in animal models, applicability to human patients remains to be determined. Similarly, the success of elbow VCA in animal models is encouraging. In the context of our group’s rat elbow VCA model, we showed that cyclosporine treatment enabled full recovery of elbow motion (90 days postoperatively).22 No elbow joint rigidity was noted throughout the experimental time course, and all other upper extremity joints regained full motion. Allotransplanted rats used their forelimb for
activities of daily living and were able to achieve normal quadrupedal ambulation. However, applicability to human patients is unclear.
Conclusion This study provides insights into the arterial and neural anatomy of the elbow in the context of VCA allograft harvest, recipient preparation, and transplantation. Elbow VCA may be technically feasible on the basis of the proposed surgical steps that preserve its vascular anatomy. Future studies evaluating elbow perfusion after cadaveric transplantation with formal microvascular anastomoses could be revealing.
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Figure 4 Recipient elbow preparation. (A) An extensile posterior incision is carried out for the left upper extremity recipient. (B) As extrafascial skin flaps are elevated, the ulnar nerve (UN) is found medially within the cubital tunnel and is decompressed. The triceps tendon is split longitudinally down its midline, and its insertion is taken sharply off of the olecranon, as distal as possible. The medial and lateral triceps tendon flaps are reflected proximally to expose the posterior surface of the humerus. (C) The ulnar nerve is neurolysed from 4.5 cm proximal to 9 cm distal to the medial epicondyle and is then transposed anteriorly. The flexor origin is taken sharply off of bone and reflected distally. (D) The median nerve (MN) and brachial artery (BA) and vein are identified anterior to the flexor-pronator mass and are dissected for a distance of 4.5 cm proximally and 12.0 cm distally to the elbow joint (the distal continuations of the radial and ulnar arteries were dissected free 1 cm and 6 cm distal to the brachial artery bifurcation, respectively). The ulnohumeral (UH) joint is visible, and care was taken to avoid taking joint capsule and synovium with the flexor pronator mass flap. (E) After lateral dissection along the posterior-distal humerus, the radial nerve (RN) is identified as it travels from posterior to anterior through the lateral intermuscular septum. The radial nerve is dissected distally, with care taken to preserve the superficial radial nerve and posterior interosseous nerve (PIN) distally. The radial tunnel is decompressed to free up the PIN. The common extensor tendon is taken sharply off of the distal humerus, and this is reflected distally. Joint capsule and synovium are excised from the common extensor tendon flap, and the radial head (RH) and radial shaft are then exposed. (F) Appearance of the recipient site after osteotomies are performed and the bony elbow has been removed. The transverse humeral osteotomy is created 9 cm proximal to the medial epicondyle, and the radius and ulna are osteotomized transversely 8 cm and 10 cm distal to the medial epicondyle, respectively. The distal biceps (DB) tendon is visible after sharp excision off of the radial tuberosity.
Table V Step No. 1 2 3 4 5 6 7 8 9 10 11
Proposed technique for elbow vascularized composite allograft transplantation
Procedure Place the donor elbow into the recipient site. Perform osteosynthesis of the radius and ulna with lateral and posteromedial 3.5-mm nonlocking plates, respectively. The recipient forearm and donor radius should be placed in full supination before plating. Perform end-to-side microanastomosis of the donor and recipient radial, ulnar, and median nerves proximally to the elbow joint. Anteriorly transpose the ulnar nerve in the subcutaneous tissue. Suture the biceps tendon stump of the donor to the recipient tendon while preserving natural length of the musculotendinous unit. Reduce the humerus diaphysis and provisionally fix with a heavy K-wire placed laterally. Perform 90°-90° plate osteosynthesis of the humerus (4.5-mm posterior and 3.5-mm lateral plates). Through the medial aspect of the posterior incision, perform end-to-side microvascular anastomosis of the donor brachial artery and recipient brachial artery as proximally as possible. Suture the matching parts of the common flexor and extensor tendons while preserving natural length of the musculotendinous unit. Suture the triceps tendon donor stump to the recipient triceps tendon while preserving natural length of the musculotendinous unit. Ensure that the pedicle is not twisted and kinked, then inset the lateral arm flap within the proximal part of the posterior incision. Close the remaining wound.
Elbow VCA—surgical anatomy and technique
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Figure 5 Proposed protocol for elbow allotransplantation. (A) The elbow vascularized composite allograft is introduced into the recipient site, the recipient forearm and donor radius are fully supinated, and osteosynthesis of the ulna is performed with a 3.5-mm nonlocking plate placed posteromedially. (B) Osteosynthesis of the radius is performed for a 3.5-mm nonlocking plate placed laterally. Both the radius and ulna are plated in compression mode. (C) End-to-side neurorrhaphy of the radial, ulnar, and median nerves is performed proximally to the elbow joint to provide proprioceptive input for the allograft. The ulnar nerve is anteriorly transposed into the subcutaneous tissue. The donor biceps and triceps tendon stumps are sutured to the recipient tendon while preserving the natural length of the musculotendinous units. (D) The donor and recipient humeri are reduced and plated with a 90°-90° construct using 4.5-mm posterior and 3.5-mm lateral nonlocking plates in compression mode. (E) End-to-side microvascular anastomosis is performed for the brachial artery and vein through the medial window. (F, G) Common extensor and flexor tendon flaps of the donor are sutured to the recipient while preserving the natural musculotendinous unit length. (H) After ensuring that the lateral arm flap pedicle is not twisted or kinked, the flap is inset within the posterior aspect of the recipient upper arm incision. The remaining wound is closed.
Disclaimer Supported by Hans Jorg Wyss foundation. The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
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