Improving the extensor lag and range of motion following free vascularized joint transfer to the proximal interphalangeal joint: Part 1. An observational and cadaveric study.

BACKGROUND: Extension lag is a common occurrence following free vascularized joint transfer reconstruction of the proximal interphalangeal joint, thus limiting the range of motion that is achievable. In this Part 1 study, the anatomical and biomechanical arrangements of the toe proximal interphalangeal joint extensor mechanism were investigated. METHODS: Twelve second toes from 12 fresh cadavers were dissected for examination of the extensor mechanism. Similar observations were performed in nine clinical cases. A total of 21 toes were therefore examined with dynamic and static testing. RESULTS: In 17 toes, the central tendon attenuated before inserting onto the middle phalangeal base (type I). In four toes, a thicker tendinous insertion analogous to a central slip was identified (type II). In type I toes, traction of the extensor digitorum brevis and digitorum longus did not correct the extensor lag. The extension lag decreased when the metatarsophalangeal joint was flexed passively or when both extrinsic and intrinsic tendons were pulled simultaneously. In type II toes, a full extension of the proximal interphalangeal joint was achieved when the extensor tendons were pulled with or without pulling the intrinsic tendons. In both types of toes, there was an increase in the extension lag caused by dorsal bowstringing when separated from the extensor sling. CONCLUSIONS: The lesser toe proximal interphalangeal joint adopts a naturally flexed posture for evolutionary reasons, with corresponding adaptations in extensor mechanism arrangements. The most significant limiting factor to full extension could be the presence of an attenuated central slip in the majority of toes.

Improving the extensor lag and range of motion following free vascularized joint transfer to the proximal interphalangeal joint: Part 2. A clinical series.

BACKGROUND: Free vascularized joint transfer for reconstructing the posttraumatic proximal interphalangeal joint has enjoyed limited popularity because of the low range of motion typically achieved after transfer. One of the commonest complaints is the significant extensor lag. Part 2 of this two-part study is focused on the clinical outcomes following a more anatomical approach to extensor tendon reconstruction. METHODS: Nine patients (eight male and one female), with a mean age of 31.7 years, underwent free vascularized joint transfer for posttraumatic proximal interphalangeal joint injuries using the second toe proximal interphalangeal joint. In Part 1, two arrangements of the central slip mechanism were found: type I with an attenuated and type II with a distinct central slip. An algorithm was constructed using this information: in a type I toe with sufficient recipient lateral bands, a centralization procedure was carried out; and when the lateral bands were insufficient, a modified Stack procedure was carried out. In type II toe joints, a tight repair of the corresponding extensor tendons was performed. RESULTS: Four patients underwent centralization procedures, two underwent a modified Stack procedure, and three underwent tight extensor repair. At 23.4 months, the average extensor lag was 18.3 degrees. A total range of motion of 53.9 degrees (mean flexion, 72.2 degrees) was achieved that approximated 81.1 percent of the pretransfer passive range of motion at the toe proximal interphalangeal joint. CONCLUSION: This preliminary result demonstrates that much improved range of motion can be achieved by reducing the extensor lag using an anatomical reconstruction that takes into account the recipient finger and toe joint anatomy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Efficient design of split anterolateral thigh flap in extremity reconstruction.

BACKGROUND: Irregularly shaped and three-dimensional soft-tissue defects in the extremities are difficult to cover precisely and efficiently. One strategy is to use the anterolateral thigh flap with two perforators and split the flap into two subunits based on separate perforators. The subunits can be rearranged into various geometric configurations to cover defects with nonelliptical shapes. Such a strategy emphasizes harvesting an elliptical anterolateral thigh flap with a narrower width to allow for primary closure in most cases. This avoids the need for skin grafting and reduces donor-site morbidity. METHODS: From 2002 to 2010, 15 patients with upper and lower limb defects were treated with split anterolateral thigh flaps. There were nine male patients and six female patients. The mean age of the patients was 40.6 years (range, 18 to 64 years). The shape of each defect was classified as arrow-shape, hourglass-shape, triangular, or three-dimensional. RESULTS: All split flaps (n = 31) survived without vascular problems. Two split flaps demonstrated margin necrosis without critical structure exposure. Only one donor site needed skin grafting. All other donor sites were closed primarily. CONCLUSIONS: The split anterolateral thigh flap is an effective strategy for covering irregular and three-dimensional defects in the extremities. It allows efficient use of the harvested flap and minimizes trimming and discarding unused flap parts. This decreases the area of skin graft needed for donor-site coverage and may even be able to achieve primary closure. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.