Purpose: Trapeziectomy for the treatment of trapeziometacarpal (TM) osteoarthritis (OA) disrupts the scaphotrapezium-trapezoidal ligament complex and may be associated with carpal collapse in a subset of patients in the form of nondissociative dorsal intercalated segment instability (DISI). The purpose of this study was to examine the clinical and radiographic outcomes of trapeziectomy, documenting the incidence of postoperative carpal collapse, and to determine whether this outcome is correlated with preoperative radiographic findings.
Methods: A retrospective chart and radiographic review was performed on 33 wrists having trapeziectomy from January 1999 to January 2006. Three surveys were administered to patients after surgery to assess subjective levels of pain, function, and satisfaction. The Wilcoxon signed-rank test was used to determine significant differences in radiographic angles, and McNemar's chi-square test was used to determine significant differences in the frequency of a DISI finding.
Results: Stage IV disease was present in 58% of wrists; all wrists were followed up at a mean of 10.5 months after surgery. The mean postoperative change in the radiolunate angle was 4.4 degrees of increased dorsal tilt. Radioscaphoid angles changed after surgery by a mean of 6.3 degrees of increased extension. The frequency of DISI as measured by the radiolunate angle increased significantly, from 27% before surgery to 50% after surgery. Scaphotrapezium-trapezoidal arthritis was observed in 58% of wrists; within this subset, DISI was present in 39% before surgery and 62% after surgery. Those patients with a DISI deformity were significantly less satisfied following surgery than those without this finding.
Conclusions: Patients having trapeziectomy for treatment of TM OA may be at risk for the development of carpal instability. This instability may manifest through either a DISI posture of the wrist or abnormal extension of the scaphoid in the presence of a normal scapholunate angle. The presence of stage IV TM OA may be correlated with an increased incidence of carpal instability after surgical intervention. These radiographic findings are mirrored by a trend toward increased levels of pain and decreased levels of function and satisfaction in those patients with evidence of DISI.
Type of study/level of evidence: Therapeutic IV.