Vascularized Composite Hand Allograft Procurement and Preparation for Distal and Proximal Forearm Allotransplantation: A Stepwise Approach

Here, we present a protocol for procuring and preparing vascularized composite hand allografts during distal or proximal forearm transplantation.

Upper limb amputations represent a real medical and surgical challenge. The ideal treatment should restore function, sensation, and body image. At present, neither traditional reconstructions nor prostheses meet all these criteria. However, vascularized composite allografts offer a unique option for restoring form and function satisfactorily despite harmful immunosuppression.

Ideally, donor tissue is procured in excess to repair without tension. The donor upper limb is procured through a fish-mouth incision at the mid-arm level. Then, the brachial artery and vein, median, ulnar, and radial nerve are located and dissected. The biceps, brachioradialis, and triceps muscles are sectioned, and then an osteotomy of the humerus is performed above the elbow. For distal forearm transplantation, the donor upper limb can also be procured below the elbow by disarticulating through the joint.

The brachial artery is cannulated, and the graft is irrigated with a preservative solution. Preparation of the graft then begins with two incisions, anterior and posterior, to raise two lateral skin flaps. A medial skin flap exposes the basilic vein, medial antebrachial cutaneous nerve, medial epicondylar muscles, ulnar nerve, median nerve, brachial artery, and vein. A lateral skin flap, including the cephalic vein, the lateral antebrachial cutaneous nerve, the radial nerve up to its division, the brachioradialis, and the lateral epicondylar muscles, completes graft preparation. In the case of transplantation, cutting guides are attached to the posterior surface of the two forearm bones to perform the osteotomies.

This protocol presents a systematized procedure for procuring and preparing a vascularized forearm composite allograft to ensure optimal results and minimize tissue damage during procurement.

Since the first successful hand transplantation by Dubernard in 1998¹, the medical community has done a lot of research and has made progress on upper extremity vascularized composite allotransplantation (VCA). The main advantage is that VCA provides a unique option to restore form and function compared to traditional prosthetics or reconstructions^2,3. Hand VCA is one of the best examples of VCA, comprising many diverse tissues: skin, neurovascular, bone, cartilage, and muscle⁴. To this date, there have been more upper extremity transplants than any other kind of vascularized composite allotransplantation⁵. Since there are some publications in the literature about the procurement and the preparation of hand VCA^6,7,8,9, we simplified the protocol and gathered the main steps of this procedure.

Upper extremity transplantation is a multiple-step complex reconstructive procedure where surgical rehearsals can decrease ischemia time and complications^8,10,11,12. Also, upper extremity transplants should be procured before solid organ procurement, and the hand procurement team needs to be trained and efficient to ensure the solid organs are not jeopardized^4,6,11,13. Hence, there is a need for a standardized protocol to reliably procure and prepare an upper extremity vascularized composite allotransplant. As Dr Robert Acland, forefather of modern-day microsurgery, said, "Preparation is the only shortcut you need in surgery."

This protocol details all the processes, from the positioning to the closure of the donor limb during an upper extremity VCA. It explains the steps to procure the graft above the elbow or in a second method through the elbow. The preparation of the procured limb is different according to the level of transplantation: proximal forearm or distal forearm. Both preparations are described in this protocol. This detailed procedure aims to standardize procuring and preparing a vascularized forearm composite allograft, which is of interest both for research and translational studies, as well as in clinical practice, given the increasing number of forearm transplants to ensure optimal results and minimize tissue damage.

The Anatomy Laboratory of the Faculty of Medicine of Nice, France, generously provided the specimens and material used for the study. The French National Ethics Committee approved this study (approval number 83.2024), which was conducted following the Helsinki Declaration.

1. Preoperative care

1. On a selected deceased organ donor, position the patient supine with the arm abducted on a hand table.
2. Apply a tourniquet over the upper donor arm, as proximal as possible.
3. Prepare and drape the limb with a pierced sterile drape rolled up distal to the tourniquet.
4. Inflate the tourniquet at 100 mmHg above the systolic blood pressure.

2. Donor upper limb procurement above the elbow (mid-humeral transection) (Figure 1)

1. Make a circumferential fish mouth incision with a surgical scalpel blade (no 15) at the mid-arm level.
2. Raise the volar proximal skin flap using fine needle cautery and a pair of Adson tissue forceps, ligating proximally and dividing the cephalic and basilic veins.
   NOTE: Ligate the structures with a 0 braided absorbable suture or hemostatic clips.
3. Expose, ligate proximally, and divide the brachial artery and veins a few centimeters above the elbow crease.
4. Dissect, with scissors, on the medial arm and transect, with a scalpel, the median nerve and the ulnar nerve deep to the medial intermuscular septum.
5. Raise the dorsal proximal skin flap using fine needle cautery and a pair of Adson tissue forceps, and clip proximally any superficial veins with hemostatic clips.
6. Identify the radial nerve deep to the lateral intermuscular septum. Transect the radial nerve with a scalpel proximal to its branches for brachioradialis (BR), extensor carpi radialis longus (ECRL), and extensor carpi radialis brevis (ECRB).
7. Isolate and transect biceps, brachialis, and triceps muscle bellies with a monopolar diathermy.
8. Make a transverse humerus osteotomy a few centimeters above the elbow joint with an oscillating saw. Ligate and divide the rest of the neurovascular bundle to detach the limb ( Figure 1).

Figure 1: Mid arm with nerves, artery, veins, and muscles transected. (1) Radial nerve, (2) Brachial artery and vein, (3) Median nerve, (4) Ulnar nerve, (5) Humerus diaphysis. Please click here to view a larger version of this figure.

3. Packaging of the graft

1. Transfer the limb to the back table for preparation for transport to the recipient center.
2. Catheterize the brachial artery with a vascular cannula with a stopcock and secure the cannula in the lumen with 2-0 silk suture ligation.
3. Flush the limb via a universal irrigation set and attach it to the stopcock in the brachial artery with 1-3 L of University of Wisconsin (UW) solution at 4 °C to preserve the graft.
   NOTE: Perfuse until clear venous outflow. Note the dominant venous system comparing the returning fluid velocity in the superficial and deep veins. Other preservation fluids, such as histidine-tryptophanketoglutarate (HTK) infused with 5000 units of unfractionated heparin, can be used.
   1. Disconnect the irrigation set and close the stopcock.
4. Wrap the limb in saline-moistened sterile towels, place it in a sealed sterile bag, and label it. Apply a second empty sterile bag, then put it in a third sterile bag filled with ice water as per standard solid organ transplantation (SOT) protocol.
   1. Place bags in the wheeled cooler and label the cooler.

4. Management of the donor residual limb

1. Remove the tourniquet after the recovery of all solid organs.
2. Complete a careful hemostasis using bipolar diathermy. Close the fish mouth incision on the arm with running or interrupted subdermal sutures followed by staples for a water-tight seal.
3. Attach the cosmetic prosthesis to the donor residual limb and roll over the sleeve of the proximal segment of the prosthesis for restoration of form.

5. Donor upper limb procurement through the elbow (elbow transection)

NOTE: Same preoperative care, with the tourniquet at mid-arm.

1. Mark the medial and lateral epicondyles to draw the fish mouth incision below the elbow joint.
2. Incise with a surgical scalpel blade (no 15) and raise the volar skin flap using fine needle cautery and a pair of Adson tissue forceps, ligating proximally and dividing the cephalic and basilic veins.
3. Incise the antebrachial fascia with a scalpel, identify, then transect with scissors the brachial artery and the median nerve under the lacertus fibrosis, ulnar to the biceps brachii tendon.
   NOTE: For proximal forearm transplantation, transect the median nerve proximal to the origin of the pronator teres branch.
4. Transect the pronator teres and forearm flexor mass through their proximal bellies with monopolar diathermy.
   NOTE: For proximal forearm transplantation, the flexor and extensor origins are dissected free along with the periosteum of medial and lateral epicondyles and not transected. This provides strong tissue for reinsertion to the recipient bone.
5. Identify and transect with scissors the ulnar nerve where it exits the cubital tunnel.
   NOTE: For proximal forearm transplantation, transect the ulnar nerve proximal to the origin of the flexor carpi ulnaris branch.
6. Transect the elbow flexors with monopolar diathermy near their distal insertion to expose the ulnar elbow joint capsule and the proximal ulna.
7. Transect the mobile wad and the common extensor mass in their proximal bellies to identify the radial nerve and expose the radial elbow joint capsule. Transect the radial nerve proximal to its division in superficial and deep branches.
   NOTE: For proximal forearm transplantation, transect the radial nerve proximal to the origin of brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis branches.
8. Incise the anterior elbow joint capsule with a scalpel. Fully flex the elbow and raise the dorsal skin flap using fine needle cautery and a pair of Adson tissue forceps.
9. Isolate and transect the triceps tendon with a scalpel, then incise the posterior elbow joint capsule to disarticulate the elbow and detach the limb fully.
   NOTE: The same packaging of the graft and management of the donor residual limb are needed.

6. Preparation of the graft for proximal forearm transplantation (Figure 2 and Figure 3)

NOTE: Tag each structure with a rectangular piece of Esmarch bandage marked with indelible ink markers and secured with 2-0 silk sutures or sterilized titanium named tags.

1. Make a longitudinal median volar incision with a surgical scalpel blade (no 15) from proximal to distal (to the mid-forearm level) and a longitudinal dorsal incision onto the shaft of the ulna up to 14 cm below the olecranon.
2. Raise the medial skin flap using fine needle cautery and a pair of Adson tissue forceps and dissect off the skin for some distance the basilic vein and the medial antebrachial cutaneous nerve with scissors.
3. Raise the lateral skin flap and dissect the cephalic vein and the lateral antebrachial cutaneous nerve.
   NOTE: The medial and lateral flaps are raised like this to interdigitate with the recipient limb's volar and dorsal skin flaps.
4. Dissect with scissors distally the ulnar nerve until the origin of the flexor carpi ulnaris branch and the median nerve until the origin of the pronator teres branch.
   1. Dissect the radial nerve with scissors and identify the BR, ECRL, and ECRB motor branches. Tag the branches and transect them at their origins from the radial nerve. Separately tag the superficial and the deep branch of the radial nerve.
      NOTE: On the recipient residual limb, radial nerve branches to BR, ECRL, and ECRB are transected close to the point of muscle entry so they can be later coapted to the donor ECRL, ECRB, and BR branches.
5. Dissect distally the brachial artery and its vena comitantes up to the division in radial and ulnar vessels (Figure 2).

Figure 2: Neurovascular structures at the proximal forearm. (1) Lateral antebrachial cutaneous nerve, (2) Cephalic vein, (3) Medial antebrachial cutaneous nerve, (4) Basilic vein, (5) Radial nerve with its branches for BR, ECRL, ECRB, deep motor branch and superficial sensitive branch in a red loop, (6) Brachial veins, (7) Brachial artery, (8) Median nerve, (9) Ulnar nerve with its branch for FCU, (10) Biceps brachialis. Please click here to view a larger version of this figure.

6. Elevate with a scalpel the origins of flexor and extensor muscle mass off the medial and lateral epicondyles in a subperiosteal plan. Elevate the brachioradialis from its humeral insertion.
   1. Dissect the radius distally from the biceps tendon insertion with a scalpel to allow plate fixation.
   2. Reflect the brachialis proximally and the forearm muscle mass distally from the proximal ulna by anterior and posterior subperiosteal dissection.
      NOTE: The biceps tendon insertion is an essential landmark for orientation and osteotomy. Be careful to preserve the deep branch of the radial nerve, and if necessary, split the interosseous membrane proximally.
   3. Continue the elevation, with a scalpel, of forearm muscles from the radius and ulna until three holes of the dynamic compression plates can be accommodated beyond the planned osteotomies (Figure 3).

Figure 3: Forearm muscle mass elevated. (1) Extensor mass, (2) Brachioradialis, (3) Flexor mass, (4) Radial nerve, (5) Brachial veins, (6) Brachial artery, (7) Median nerve, (8) Ulnar nerve. Please click here to view a larger version of this figure.

7. Preparation of the graft for distal forearm transplantation (Figure 4 and Figure 5)

NOTE: Tag each structure with a rectangular piece of Esmarch bandage marked with indelible ink markers and secured with 2-0 silk sutures or sterilized titanium named tags.

1. Make mid-axial volar and dorsal incisions up to wrist level distally using a surgical scalpel blade (no 15). Release the carpal tunnel with the volar incision.
2. Raise radial and ulnar skin flaps with the antebrachial fascia using fine needle cautery and a pair of Adson tissue forceps. Preserve the skin perforators of the distal forearm on both flaps.
3. Dissect off the radial skin flap, the cephalic vein, and the lateral antebrachial cutaneous nerve with scissors. Dissect off the ulnar skin flap, the basilic vein, and the medial antebrachial cutaneous nerve.
4. Identify and excise the brachioradialis with fine needle cautery and dissect the radial sensory nerve underneath.
5. Elevate the abductor pollicis longus (APL) and the extensor pollicis brevis (EPB) by opening the first compartment with a scalpel.
   NOTE: Skeletonize all tendons with a scalpel by excising the muscle to leave the tendinous part as long as possible for repair.
   1. Isolate ECRL and ECRB, and dissect the extensor pollicis longus (EPL) free from its sheath.
   2. Identify the extensor indicis proprius (EIP), extensor digitorum communis (EDC), and extensor digiti minimi (EDM). Elevate the extensor carpi ulnaris (ECU) (Figure 4).
      NOTE: EIP, EDC, and EDM can be sutured together if individual repair is not possible during transplantation.

Figure 4: Extensor tendons dissected. (1) APL, (2) EPB, (3) ECRL and ECRB, (4) EPL, (5) EIP, (6) EDC, (7) EDM, (8) ECU. Please click here to view a larger version of this figure.

6. Dissect the radial artery and its vena comitantes using scissors and Adson tissue forceps.
   1. Isolate the flexor carpi radialis (FCR) and excise the palmaris longus with a scalpel. Dissect the median nerve.
   2. Identify each tendon of flexor digitorum superficialis (FDS), the flexor pollicis longus (FPL) and the 4 tendons of flexor digitorum profundus (FDP). Elevate the flexor carpi ulnaris (FCU).
      NOTE: FDS can be sutured together, and the same is true for FDP if individual reparation is not possible during transplantation.
   3. Dissect carefully with scissors the ulnar artery and nerve to identify the dorsal sensory branch of the ulnar nerve.
   4. Excise the pronator quadratus (PQ) with fine needle cautery. Expose the volar side of the radius and ulnar side of the ulna until three holes of the osteosynthesis plates can be accommodated beyond the planned osteotomies (Figure 5).
      NOTE: Be careful with the anterior interosseous artery on the interosseous membrane at this level.

Figure 5: Flexor tendons and neurovascular bundles dissected. (1) Radial sensory branch, (2) Cephalic vein, (3) Medial antebrachial cutaneous nerve, (4) Basilic vein, (5) Radial artery, (6) Anterior interosseous artery, (7) Median nerve, (8) Ulnar nerve with its dorsal sensitive branch, (9) Ulnar artery, (10) FCR, (11) FCU, (12) FPL, (13) FDS, (14) FDP. Please click here to view a larger version of this figure.

At the end of this protocol, the donor limb should be ready for transplantation on the receiving residual limb. The radius and ulna are sufficiently exposed for the osteosynthesis with a 3.5-mm locking compression plate^14,15,16 or 2.7-mm volar locking distal radius and ulna plates in distal forearm transplant. The brachial or radial and ulnar arteries are dissected depending on the level, allowing arterial anastomosis. Deep and superficial veins are also isolated, and the first anastomosis should be on the dominant venous system¹⁷. Donor tendons are dissected long enough to be repaired with the Pulvertaft weave technique¹⁴ or single-weave, "Brown" side-to-side tenorrhaphy^18,19. In proximal transplant, the flexor mass, mobile wad, and extensor mass are fixed to the recipient's epicondyles by trans-osseous sutures²⁰ or boneanchor¹⁶. Nerves are dissected enough to allow tension-free repair¹¹. Finally, the two skin flaps will interdigitate with the volar and dorsal flap of the recipient residual limb to accommodate post-operative edema, preventing constriction and scar contracture at the closure site²¹.

During the dissection of six grafts, we measured with a caliper the dimensions of all vessels and nerves eligible for anastomosis. For the proximal forearm level, we found the mean diameter as follows (mean ± SD): brachial artery 5.17 ± 0.85 mm, brachial vein 3.75 ± 0.95 mm, cephalic vein 2.67 ± 0.79 mm, basilic vein 2.25 ± 0.07 mm, radial nerve branch to brachioradialis 0.84 ± 0.25 mm, deep branch of radial nerve 2.5 ± 0.54 mm, the sensitive branch of radial nerve 2.34 ± 0.51 mm, median nerve 6 ± 0.82 mm, ulnar nerve 4.75 ± 0.50 mm, medial antebrachial cutaneous nerve 3 ± 0.82 mm, lateral antebrachial cutaneous nerve 2.34 ± 0.48 mm.

Figure 6: Average diameters (in mm) of vessels and nerves of interest at the proximal forearm level (BR = brachioradialis, RN = radial nerve). Please click here to view a larger version of this figure.

For the distal forearm level, we found the mean diameter as follows (mean ± SD): radial artery 4 ± 0.41 mm, ulnar artery 4.25 ± 0.50 mm, cephalic vein 1.88 ± 0.25 mm, basilic vein 1.25 ± 0.50 mm, sensitive branch of radial nerve 2.08 ± 0.25 mm, median nerve 4.5 ± 0.58 mm, ulnar nerve 4 ± 0.82 mm.

Figure 7: Average diameters (in mm) of vessels and nerves of interest at the distal forearm level (RN = radial nerve). Please click here to view a larger version of this figure.

In 2022, a systematic review of the outcomes of hand allotransplantation by Wells et al.² found the following results: With 96 patients receiving 148 hand transplantation, with at least 98 at the forearm or wrist level, the success rate of the transplant was 89.2%. For the functional results, the DASH scores significantly decreased (P < 0.001) after hand transplantation. The post-operative disability scores for distal transplants (median, 16; IQR, 31.8) were significantly lower than those of proximal transplants (median, 38.5; IQR, 36; P = 0.035).

In the literature, multiple cases reported of proximal and distal forearm transplantation show overall good clinical evolution of the patients. This protocol described the procurements above the elbow (mid-humeral transection) for proximal transplantation¹⁶ and through the elbow (elbow disarticulation) for distal transplantation²².

This protocol presents some critical steps. First, the skin flap incisions are marked. The goal is to properly match the flaps to ensure sufficient tissue to close over the bulky tendon anastomoses without skin surplus, which can lead to bulky skin adaptation. Furthermore, distal tip perfusion of the flaps should be ensured. To help in this surgical planning, three-dimensional (3D) stereophotogrammetry and 3D-printed skin incision guides can be useful, as Hummelink et al.²³ described. The radial nerve must be transected proximal to its branches for BR, ECRL, and ECRB for proximal transplantation. This allows targeted anastomosis at the branch level rather than one proximal trunk-level radial nerve anastomosis, permitting less axonal loss between sensory and motor fascicles. Also, the distance for reinnervation will be diminished^21,24.

The repair of the radial nerve depends on the level of initial amputation. The anastomosis can be performed directly on the sensory radial branch and motor posterior interosseous radial branch¹⁴.

Another pitfall is during the preparation for a distal forearm transplant. The anterior interosseous artery must be carefully identified during the exposition of the distal radius and ulna because an anastomose is feasible. This allows the graft to rely on three main arteries instead of two¹.

Two methods of procurement are described in the literature. The first is the approach of the Massachusetts General Hospital (MGH) team, where the preparation with detailed dissection of the structures is performed in situ on the donor before a tourniquet release (20 min for 2 h of dissection), allowing reperfusion. The second method is the University of Pennsylvania (Penn) "cut and run" approach. In this case, the procurement is very rapid. In 20 min, all preparation is done after transportation to the recipient hospital⁸. The main advantage of the MGH method is that it reduces the ischemia time for the entire case. During the procurement, the brachial artery and veins need to be dissected but not ligated until the end of the reperfusion period¹⁸. The main problem is the logistical aspect with the SOT teams who wait and the risk of compromising the viability of solid organs if the donor becomes unstable¹¹. In comparison, the Penn method allows quick procurement and does not impede additional teams for organ recovery. However, the ischemia time begins at the tourniquet inflation²⁵.

The two procurement levels described in this protocol are possible for proximal forearm transplantation. Either above the elbow at mid-humerus level^6,14,19,21 or the elbow²⁶. However, in the case of elbow disarticulation, some dissection steps need to be adjusted: the nerve dissection needs to be proximal to the motor branches of the main nerves. Furthermore, the flexor and extensor mass must be respected and elevated in a subperiosteal plan rather than transected as in a distal forearm transplant^16,26. This modification allows the preservation of the entire musculotendinous functional units essential in proximal forearm transplantation.

Concerning the preparation of the graft, there are major differences depending on the level of transplantation. In distal transplantation, the anatomic disadvantage, compared to proximal transplantation, is that each flexor and extensor tendon is individually dissected and repaired. However, an early active range of motion can be safely initiated, and there's no delay due to the reinnervation of flexors/extensors, allowing good function early after the surgery^4,14.

After transplantations at more proximal levels, the outcome is less consistent and appears later^20,27. The main difference is the reinnervation from a greater distance of the intrinsic muscle. This distance causes a progressive inhibition of nerve regeneration and alters the function^16,24,26.

This protocol presents some limitations as the research was done on cadavers and not on a deceased donor and is based on our Nice (France) experience. Also, the level of amputation may vary on the receiving residual limb, and the preparation of the transplant may be modified according to the protocol described here.

The authors have no disclosures.

The authors would like to thank the individuals who donated their bodies to facilitate the anatomical research.