Does The Suspension Angle Affect Postoperative Metacarpal Subsidence in Trapeziectomy with Suture Button Suspensionplasty? A Preliminary Report

Previous literature reported that postoperative metacarpal subsidence is frequently observed in patients receiving trapeziectomy and suture-button suspensionplasty with subsequent decrease of thumb strength and increase of pain. In this study, we aim to investigate whether the suspension angle and other postoperative radiological factors have a correlation with the metacarpal subsidence of these patients.

16 cases (mean age 63.8 years old, male-to-female ratio 4:12, right-to-left ratio 3:13) were included with symptomatic TMC arthritis more than 3 months. Preoperative plain films showed TMC arthritis with Eaton & Littler classification III-IV. Operations were conducted between January 2021 and October 2023. Average follow-up time is about 9.2 (3 to 23) months. Total trapeziectomy was done in all cases with following suture-button suspensionplasty under the guidance of image intensifier. Metacarpal subsidence was defined as the difference between the ratio of trapezial space to 1st metacarpal height at postoperative day 1 and the ratio at postoperative 6 months/ final follow-up. Postoperative radiological factors were measured including suspension height ratio, suspension length ratio and three categories of suspension angle, which were defined first time in this study. We use Pearson correlation analysis to compare these radiological factors with metacarpal subsidence.

In our series, the average postoperative metacarpal subsidence at 6 months and final follow-up were 0.24 and 0.35, respectively. The average suspension height ratio was 0.33, the suspension length ratio was 0.74, the suspension angle was 22.3 degrees, the 1st suspension angle was 69.5 degrees, and the 2nd suspension angle was 48.6 degrees. There was no statistical significance between postoperative metacarpal subsidence and the postoperative radiological factors. The revision rate is 6% (1 out of 16), and the revision case has a lower suspension height ratio (0.25) and a higher 1st suspension angle (89.8 degrees) when she received the first surgery.

In our experience, the metacarpal subsidence following by trapeziectomy with SBS procedure is comparable to previous studies, and the revision rate is low. This is the first clinical study aiming to determine the optimal suspension angle, however the result did not indicate a significant trend. Further studies including more cases of trapeziectomy with SBS may be needed to clarify the result. 

Keywords: Trapeziometacarpal Arthritis, Metacarpal Subsidence, Suture Button Suspensionplasty