Back to Annual Meeting Program

Introduction

Midcarpal Instability (MCI) is loosely defined as a laxity of the midcarpal joint. It is commonly caused by a malfunction of the ligaments between the proximal and distal bone rows. Patients demonstrating MCI exhibit a painful clunking with ulnar deviation and pronation of the wrist upon examination. MCI continues to spark much debate regarding its pathomechanics and appropriate treatment. The purpose of this study was to present our results and experience with arthroscopic shrinkage capsulorrhaphy for MCI.

Materials & Methods

This retrospective review investigated the medical records of all patients that underwent electrothermal capsular shrinkage surgery for MCI between 2005 and 2012. Patient demographics as well as pre and postoperative data were recorded. This included measurements of wrist flexion, wrist extension, grip strength and the midcarpal shift test. Complications were also recorded. A paired t-test was used to compare two means. A p-value less than 0.05 was considered statistically significant.

Results

The total study population included 28 patients: 14 male and 14 female. The average age at time of surgery was 27.9 with 18 right-sided injuries and 6 left-sided. The mechanisms of injury were classified as acute (14), chronic (10) and unknown (4). 5 patients had a history of previous trauma of the affected hand. Postoperative follow-ups were an average of 4.2 months from surgery, ranging from 0.6 to 15.9 months.

18 subjects had pre and postoperative records of midcarpal shift tests. Postoperatively, 94.4% displayed a negative midcarpal shift test. The average pre and postoperative wrist flexion was 59.4º and 43.9º respectively, n = 18, p < 0.001. The average pre and postoperative wrist extension was 68.3º and 50.0º respectively, n = 18, p < 0.001. The averages for grip strength testing in the symptomatic wrist were 49.3 lbs preoperatively and 41.0 lbs postoperatively, n = 10, p = 0.388.

Conclusions

MCI remains a difficult problem to treat. Our preliminary results are encouraging but should be interpreted carefully. While the postoperative assessments exhibited a predominant absence of midcarpal shift, they also demonstrated a statistically significant loss of wrist flexion and extension. This suggests that electrothermal capsular shrinkage may be an effective treatment for MCI in terms of providing joint stability, but appears to have its own limitations. Since the patients were evaluated at an average of 4.2 months postoperatively, it is unclear how stability and range of motion will change with time. Longer follow-up is required.