Summary

Acromial thickness decreased significantly in the year after ARCR with ASD compared with just after surgery as well as before surgery regardless of knot use.

Abstract

Introduction

There are some reports that acromiohumeral interval (AHI) influences clinical outcome after arthroscopic rotator cuff repair (ARCR), but there is few report that investigated morphologic change of acromion after ARCR. We assessed acromial thickness over time after ARCR.

Materials And Methods

From 2013 to 2016, ninety-six patients at our institution underwent ARCR with arthroscopic subacromial decompression (ASD). Of these, we followed-up 27 (male 9; female 18; average age 68.9 years) over 1 year and classified them into two groups: knot-use ARCR (17) and knotless ARCR (10). MRI revealed no rotator cuff re-tear after surgery. We measured acromial thickness on radiographic scapular Y views before surgery, just after surgery, and 1 year after surgery and compared the results (Tukey’s test; P < 0.05). We also compared acromial thickness between the knot-use and knotlessgroups (t-test; P < 0.05).

Results

Before ASD with ARCR, acromial thickness averaged 9.9 mm (7.7–12.6 mm). Just after surgery, acromial thickness had decreased significantly to 8.5 mm (5.0–11.2 mm) (P = 0.0001). One year after surgery, acromial thickness had again decreased significantly to 7.9 mm (5.5–11.7 mm) (P = 0.003); there was a 0.4-mm decrease in acromial thickness in the knot group and a 0.8-mm decrease in the knotless group compared with just after surgery; the between-group difference was not significant (P = 0.24).

Conclusion

Acromial thickness decreased significantly in the year after ARCR with ASD compared with just after surgery as well as before surgery. This decrease was unrelated to whether or not knots were used. We speculate that the inferior acromial surface, where cancellous bone was exposed, was worn away in adapting to the form of the repaired rotator cuff.