The effect of subtendinous connective tissue restraints on extension of the vascularized toe joint transfer: a propensity score-matched comparison.

Abstract

Vascularized toe proximal interphalangeal (PIP) joint transfer restores motion after destructive finger injuries, yet outcomes are limited by a persistent extensor lag. We observed subtendinous connective tissue attachment beneath the extensor digitorum longus (EDL), from the proximal phalangeal neck to the PIP joint, that may tether the tendon to bone. We assessed whether releasing this tissue improves surgical outcomes without compromising perfusion. We performed a retrospective matched cohort study with a 1:1 propensity score matching on sex, age at surgery, native toe passive range of motion (ROM) and follow-up duration, comparing transfers with subtendinous tissue dissection to cases without dissection. Matched cohorts included 17 dissected and 17 non-dissected joints. The primary outcome was extension lag of the transferred PIP joint at final follow-up. Secondary outcomes included active PIP joint ROM, active flexion, percentage of use (active ROM ÷ donor toe passive ROM ×100), revision incidence and number of revision procedures per patient. Early follow-up was defined as 6 months postoperatively, and final follow-up as the most recent outpatient visit. Patients with follow-up <12 months were excluded. At the 6 month postoperative assessment, prior to any revision procedures, the dissected group demonstrated less extension lag (15° vs. 20°, <i>p</i> = 0.014) and greater ROM (55° vs. 45°, <i>p</i> = 0.017). At final follow-up, extension lag remained less (15° vs. 20°, <i>p</i> = 0.032), whereas ROM, flexion and percentage of use did not differ. The revision burden was similar between groups. Donor-side release of the subtendinous tissue beneath the EDL was associated with reduction in early and final extension lag without vascular compromise. These findings should be interpreted cautiously and warrant confirmation in larger studies with longer follow-up. III.