5: Metacarpal Subsidence Following Trapeziectomy
Authors: Meyers Abigail E. , Krebs Jillian P. , Smith Arvin , Rampazzo Antonio , Bassiri Gharb Bahar 
Published: July 2021

Purpose: It is controversial whether subsidence after trapeziectomy prognosticates pain, poor outcomes, and need for revision. The aim of this study was to investigate the degree of subsidence following trapeziectomy and whether subsidence contributes to poor outcomes.

Methods: An IRB approved retrospective review of all patients who underwent trapeziectomy for osteoarthritis of the first carpometacarpal (CMC) joint was conducted from 2003 to 2019. Patients with available radiographic imaging greater than three months postoperatively were included. Patients with arthritis of the metacarpophalangeal joint of the thumb, arthritis of radiocarpal, distal radioulnar, and midcarpal joints were excluded. Demographic information, pain scores, and revision procedures were recorded. Conolly-Rath patient function scores were determined. Subsidence was measured by the ratio of the difference between the trapezial space (TS = distance from base of thumb metacarpal to scaphoid) preoperatively and TS postoperatively over the TS preoperatively. Patients were divided as having a high degree of subsidence (≥50%) or low degree of subsidence (<50%). Pain scores (median and interquartile range) were compared before and after surgery, as well as between high and low subsidence groups using Mann-Whitney U tests. Age was compared between the two groups using an unpaired t-test. P value <0.05 was considered significant.

Results: One-hundred-eighty-six patients, who underwent 211 primary trapeziectomies, were included. The average age at the time of surgery was 61 years (range 18-86). Eighty-five percent of patients were female. Average follow-up was 38.2±31.9 months (range 3-146.5 months). Metacarpal subsidence was present in all patients after trapeziectomy (average 58.0±20.8%). There was no significant difference in age (p=0.49), pre-op (p=0.19) or post-op (p=0.72) pain between patients with high and low subsidence. Sixty-eight percent of patients had high subsidence (69.2±13.6%). The average age was 60±10.6 years (range 18-86 years) and 80.9% were female. Pain decreased significantly from 6 (5-8) to 1 (0-2)(p<0.001) after surgery. Based on Connolly-Rath scores 25.7% had good, 48.7% fair, and 25.7% poor outcomes. Thirty-two percent of patients had low subsidence (34.6±12.1%). In this group, the average age was 61±8.7 years (range 37-84 years) and 87.4% were female. Pain decreased significantly from 7 (6-9) to 0 (0-3) (p<0.001) in this group and there were 8.9% good, 33.9% fair, and 57.1% poor outcomes. There were 7 revisions in 5 patients (revision rate 3.3%). There was one male and 4 female patients. All patients were right-handed. Right side was revised in 3 cases and left side in 4. In this cohort, after primary trapeziectomy, the average subsidence was 76.7±24.0% (range 33.1%-100%). In 4 cases, the trapezial space increased after revision surgery (subsidence decreased from 72.0±28.0% to 56.9±0.1% after revision); in 1 case the subsidence increased (from 59.2% to 70.2%). One hundred percent subsidence persisted in 2 cases. Three patients had good outcomes, 1 fair, and 3 poor outcomes based on Conolly-Rath scores after revision.

Conclusions: Post-trapeziectomy, pain scores improved significantly in patients with both high and low subsidence. While all patients subside after surgery, it is rare that subsidence is symptomatic and requires revision.