Single-Ball Versus Double-Ball Flexor Carpi Radialis Interposition Arthroplasty Following Trapeziectomy: A Retrospective Radiological Study

Introduction The trapeziometacarpal (TMC) joint represents the second most prevalent site of osteoarthritis in the hand. Following trapeziectomy, ligament reconstruction with tendon interposition (LRTI) is widely considered the gold standard treatment. However, there is currently no objective radiographic evidence comparing single-ball (SB) versus double-ball (DB) flexor carpi radialis (FCR) tendon interposition in preventing first metacarpal collapse after surgery. Methods A total of 20 patients who underwent trapeziectomy and LRTI with an FCR graft from 2013 to 2023 were retrospectively analyzed (divided into 10 SB and 10 DB cases), with a minimum radiographic follow-up of one year. Standard posteroanterior radiographs were analyzed to compare preoperative and one-year postoperative parameters, including trapezial void height (HT1 vs HT2), first metacarpal subluxation (MS1 vs MS2), and first metacarpal migration (MM1 vs MM2) measured at baseline and one year postoperatively. Results Baseline characteristics did not differ significantly between groups. At one year, the DB group showed a statistically superior trapezial void height (HT2) compared to the SB group (mean difference, -2.98 (95% CI, -5.22 to -0.74); p < 0.05). Conversely, no significant intergroup differences were found in first metacarpal subluxation (MS2) (mean difference, -0.60 (95% CI, -3.45 to 2.25); p = 0.663) or migration (MM2) (mean difference, 2.80 (95% CI, -1.43 to 7.02); p = 0.181). Conclusions  At one year, the DB technique showed higher absolute trapezial void height than the SB technique. The loss of height from baseline did not differ significantly between groups. Subluxation and migration of the first metacarpal were also similar. Given baseline differences and the lack of functional data, these exploratory results do not establish superior joint space preservation or better clinical outcomes.