Volar A1 pulley sparing technique for fixation of avulsion fractures of the base of the proximal phalanx

Outcomes of a Trans-Web Approach to Fractures around the Finger Metacarpophalangeal Joint

Background: A fracture around the finger metacarpophalangeal joint (MCPJ) can be difficult to access. We developed a trans-web approach that could lead surgeons directly to this site. An incision across the web is believed to result in a web contracture. The aim of this study is to present the outcomes of the trans-web approach. Methods: This is a retrospective study of all patients in whom a trans-web approach was used to fix fractures around the MCPJ in the period from October 2008 and September 2020. The outcomes of the trans-web approach were evaluated by appearance of the scar, presence of pain in relation to the scar, grading web creep, range of motion at the MCPJ and degree of abduction and adduction of the finger. Any complications of surgery were also recorded. Results: This study included 10 patients with 11 fractures around the MCPJ (6 avulsion fractures and 5 extra-articular fractures). The mean follow-up was 5 months. Skin contractures did not occur in any avulsion fracture case where original or extended trans-web skin incisions were used. However, they occurred in 2 extra-articular cases treated via a trans-web plus a mid-lateral approach. The mean range of motion of the MCP joint in all the patients was 80° (range, 70°-95°). There was a 10° loss of abduction in one patient and temporary sensory disturbance in another patient. Both these patients had been treated with extended incisions. Conclusions: The trans-web incision is a useful approach for the open reduction of fractures around the finger MCPJ, especially in avulsion fractures of the lateral volar base of the proximal phalanx with minimal risk of scar contracture. The risk of scar contracture is higher when the trans-web incision is combined with a mid-lateral incision for extra-articular fractures. Levels of Evidence: Level IV (Therapeutic).

Dorsal and Volar Surgical Approaches to the Metacarpophalangeal Joint: A Comparative Anatomic Study

BACKGROUND

We compared 3 surgical approaches to the MP joint: a dorsal extensor tendon-splitting approach, a dorsal extensor tendon-reflecting parasagittal approach, and the volar A1 pulley approach. We quantitatively compared each of these approaches by measuring the amount of articular cartilage exposed on the base of the proximal phalanx. We hypothesize that visualization of the articular cartilage of the proximal phalangeal base is enhanced with the volar approach.

METHODS

The MP joints of the 32 available digits were randomly assigned to 1 of 3 surgical approaches: extensor tendon splitting (A), extensor tendon reflecting (B), or volar approach (C). After each approach, the visible articular surface of the base of the proximal phalanx was stained with methylene blue. The MP joints were then disarticulated, and the proximal phalanges were digitally mapped using a 3-dimensional digitizer. Three-dimensional computer software was used to analyze and calculate the dyed exposed surface area and total surface area of each specimen.

RESULTS

The mean % exposed joint surface area for the dorsal extensor splitting, dorsal extensor reflecting and volar approaches were 62%, 67% (over the dorsal side of the proximal phalanx) and 54% (over the volar side of the proximal phalanx), respectively. Multiple linear regression showed statistical significance for a smaller percentage of articular surface area exposed with the volar approach. However, this was not clinically significant. A significant association was found between location in the small finger and greater % exposed joint surface, compared to approaches in the index finger. In all volar approach specimens, the collateral insertion site was visible, but not in the dorsal approach specimens.

CONCLUSIONS

Knowledge of the limits of each exposure is essential for planning the most appropriate surgical approach. The A1 pulley approach provided greater access to the volar 50% of the joint and collateral ligament insertion without violating the extensor mechanism. The amount of joint surface visualized through all 3 approaches was not significantly different. However, based on the accessibility to the collateral ligament insertion site among three different approaches, we recommend the volar A1 pulley approach for treatment of avulsion fractures of the base of the proximal phalanx. For other injuries of the MP joint, including the intra-articular proximal phalanx base fractures, and metacarpal head fractures, the dorsal approaches are still indicated.