INFLUENCE OF BONY GLENOID LESIONS ON THE OUTCOME AFTER ARTHROSCOPIC TREATMENT FOR CHRONIC ANTERIOR SHOULDER INSTABILITY

Abstract

Purpose of the study: This retrospective study was conducted to analyze the mid-term effect of damage to the anteroinferior rim of the glenoid cavity in failed arthroscopic stabilization of the shoulder.

Material and methods: From 1999 to 2001, 54 patients underwent surgery performed by the same operator. Full data were available for analysis for 46 patients. Mean age was 28 years and mean follow-up four years. A pre-operative scan was available for all patients to analyze the bone lesions. The same technique was used for all shoulders: three or four suture points using resorbable thread attached to a Panolok anchor with a north-south retension effect. The Duplay score was noted at last follow-up. Experimental work by Gerber, which demonstrated that the anti-dislocation resistance decreased as a function of the ratio (x) between the length of the anteroinferior glenoid defect and its maximal antero-posterior diameter, was used to assess resistance to dislocation. This resistance decreased 30% when x=0.5 and 50% when x=0.75.

Results: The Duplay score at 47 months was 83.3. The rate of recurrence was 13% (n=6). Age, sex, and number of episodes of instability had little effect on outcome. The rate of recurrence (38%) in patients with a significant damage (x> 0.5) was much higher than in patients with minimal damage (x< 0.5) (2.2%). The difference was statistically significant (p< 0.01). The Duplay score (63.8 points) in patients with significant damage (x> 0.5) was significantly lower (p=0.01) than in patients (91 points) with minimal damage (x< 0.05).

Discussion: The presence of bony lesions of the anterior glenoid rim appears to be one of the most important prognostic factors of recurrence. Considering the high frequency of these lesions in our series (54%), this element deserves careful analysis which would require computed tomographic reconstruction in the sagittal plane to obtain a precise assessment of the loss of articular surface. The statistical analysis demonstrated that patients with important loss of articular surface (x> 0.5) had a significantly higher risk of recurrent instability (p< 0.01).

Conclusion: Arthroscopic stabilization of the shoulder joint yields results similar to those obtained with more conventional techniques. Our study confirmed this notion showing a rate of recurrence of 13% which could be reduced to less than 3% with careful preoperative assessment of glenoid articular surface loss on the preoperative scan.