Vascularized Joint Transfer
Nonvascularized joint transfers undergo cartilaginous degeneration and invasion of joint space by fibrous tissue soon after surgery, leading to narrowing of joint space and loss of mobility.1 The key point in performing vascularized joint transfers is to enable production of synovial fluid within 14 days postoperatively to maintain the viability of the articular hyaline cartilage and to prevent its replacement by fibrocartilage. Current treatment options for dysfunctional metacarpophalangeal joint (MCPJ) and proximal interphalangeal joint (PIPJ) include arthrodesis, implant arthroplasty (silicone or PyroCarbon), and vascularized joint transfer. Vascularized toe joint transfer has several advantages over other options, including no foreign body, preservation of joint motion, preservation of epiphyseal growth plate in children, and the ability to transfer composite tissues for simultaneous reconstruction of joint, tendon, and overlying soft tissue.
The principles and techniques described in this chapter are based on our experience with vascularized joint transfers involving toe PIPJ to hand PIPJ. However, the same principles are applicable for harvesting toe metatarsophalangeal joint (MTPJ) for reconstruction of hand MCPJ. The only caveat is that the toe MTPJ has a higher excursion in extension than in flexion, therefore, 180-degree rotation upon its long axis (so the original dorsal surface now becomes the volar surface) is recommended upon transfer to the hand to maximize flexion of the reconstructed MCPJ. Typically, the toe PIPJ is transferred to hand PIPJ. Although either the toe MTPJ or PIPJ can be used to reconstruct the MCPJ, MTPJ provides a better size match. In addition, the use of MTPJ is preferred in pediatric MCPJ reconstruction due to the presence of two growth centers that can restore the growth potential of the reconstructed digit.
Ideal candidates include healthy children and young adults.
Indications for vascularized joint transfer include reconstruction of stiff or painful PIPJ/MCPJ of the hand in patients requiring manual dexterity (e.g., musician) or in children with the goal to preserve epiphyseal growth.
Most vascularized joint transfers are performed in a delayed fashion, after all conservative measures have failed to achieve a functional arc of motion (AOM) for the injured joint.
Absolute contraindications include patients with rheumatoid arthritis or other systemic inflammatory conditions that may affect joints throughout the body.
Relative contraindications include history of trauma to the toe planned for transfer (injury to vessel or joint) and patients who are not motivated or cannot comply with the extensive postoperative rehabilitation therapy. Also, a history of Raynaud′s phenomenon and active smoking are both relative contraindications.
Preoperative examination of the toe planned for transfer is critical. The passive range of motion of the toe PIPJ should be assessed to ensure there is no contracture. Quality of the soft tissue around the joint should also be evaluated, since a small skin flap is harvested along with the vascularized joint for postoperative monitoring. We do not routinely obtain X-rays of the toe planned for transfer. If there is any sign of toe joint stiffness or disease on physical exam, we will advise the patient not to undergo vascularized joint transfer. Similarly, angiography of the toe is not routinely performed unless there is a high suspicion or history of vascular injury or disease.
The blood supply to the second toe comes from both the dorsal and plantar arterial systems. In ~ 70% of patients, the dorsal arterial system is dominant. The dorsal arterial system is fed by the dorsalis pedis artery, which becomes the first dorsal metatarsal artery (FDMA). When the FDMA reaches the first web space, it gives off two dorsal digital arteries (one to the great toe and one to the second toe) and then sends off a communicating branch to the first plantar metatarsal artery (FPMA). The FDMA lies dorsal, and the FPMA lies plantar, to the deep intermetatarsal ligament ( Fig. 35.1 ). The blood supply to the PIPJ of the second toe comes from branches of the proper tibial and fibular digital arteries. In proximity to the toe PIPJ, there are often small vascular branches to the skin arising from the proper tibial and fibular digital arteries, thereby allowing inclusion of a reliable skin island for postoperative monitoring. The vascularized PIPJ is harvested based on one single digital artery (tibial or fibular, depending on the design of the skin island), preserving the contralateral digital artery to maintain viability of the remaining second toe.
A basic hand set with tenolysis instruments, along with a standard set of microinstruments, will suffice. No special instrumentation is required.
The patient is positioned supine with the arm on the hand table and the donor lower extremity flat on the operating table.
Both an upper arm tourniquet and a thigh tourniquet are applied.
General anesthesia is used for the procedure.
Design the skin island on the tibial surface of the toe PIPJ to enable visualization of the toe extensor mechanism and adequate reconstruction at transfer. This also allows an easier approach and dissection of the vascular pedicle.
Preexisting soft-tissue contracture of the recipient finger will require a contracture release. A large skin island will need to be included in the joint transfer to replace the soft-tissue deficit. Donor toe preservation will be impossible in this case.
Harvest proper bone length on each side of the vascularized joint to achieve stable bony fixation and prevent extension lag.
Align flexion/extension axis of the transferred joint intraoperatively with the longitudinal axis of the reconstructed digit to prevent rotational deformity.
Nonunion of bone graft to the donor site
Extensor tendon adhesion/extension lag
Incision Placement and Dissection
Toe Donor-Site Marking
In general, we prefer to use the second toe PIPJ as the donor joint. A venous tourniquet is applied to the midfoot for mapping the dorsal foot venous system.
We always place the skin island on tibial side of the transferred toe joint ( Fig. 35.2 ). The skin island acts as a postoperative monitor for perfusion of the transferred joint and also functions as soft-tissue replacement for preexisting soft-tissue contracture (if any) that will be excised from the recipient finger. Based on the location of the contracture excision, the left or the right toe PIPJ is harvested. For example, if contracture is excised from the ulnar side of a left-hand digit or the radial side of a right-hand digit, then the right toe PIPJ is used because the skin island is designed on the tibial side of the right toe. The skin island of the left toe PIPJ will be on the opposite side of the contracture and cannot be used. When there is soft-tissue contracture on the recipient site, we include a large skin island from the donor toe to replace the soft-tissue deficit and sacrifice the donor toe (toe amputation). When there is no soft-tissue deficit at the recipient site, we preserve the donor toe soft-tissue envelope and harvest only a narrow skin island along with the toe PIPJ.
A fusiform skin island is designed and centered on the tibial side of the toe PIPJ. If there is soft-tissue deficit at the recipient site, the size of the skin island should be designed accordingly, with the plan for donor toe amputation. If there is no soft-tissue deficit at the recipient site, only a small skin island needs to be harvested to help with tension-free wound closure of the recipient finger and postoperative monitoring. The width of the skin island can be estimated by a pinch test. In most instances, a ~ 5–6 mm wide skin island can be harvested while allowing primary closure. In these cases, the distal tip of the skin island is set at the tibial surface of the distal interphalangeal joint. The proximal tip is extended to the dorsotibial surface of the proximal phalanx in line with the orientation of the dorsal vein.