Purpose The purpose of this study was to evaluate the correlation of rotator cuff musculotendinous junction (MTJ) retraction with healing after rotator cuff repair and with preoperative sagittal tear size. Methods We reviewed preoperative and postoperative magnetic resonance imaging (MRI) studies of 51 patients undergoing arthroscopic single-row rotator cuff repair between March 1, 2005, and February 20, 2010. Preoperative MRI studies were evaluated for anteroposterior tear size, tendon retraction, tendon length, muscle quality, and MTJ position with respect to the glenoid. The position of the MTJ was referenced off the glenoid face as either lateral or medial. Postoperative MRI studies obtained at a minimum of 1 year postoperatively (mean, 25 ± 13.9 months) were evaluated for healing, tendon length, and MTJ position. Results We found that 39 of 51 tears (76%) healed, with 26 of 30 small/medium tears (87%) and 13 of 21 large/massive tears (62%) healing. Greater tendon retraction, worse preoperative muscle quality, and a more medialized MTJ were all associated with worse tendon healing (P <.05). Of tears that had a preoperative MTJ lateral to the face of the glenoid, 93% healed, whereas only 55% of tears that had a preoperative MTJ medial to the face of the glenoid healed (P <.05). Healed repairs that had limited tendon lengthening (<1 cm) and limited MTJ position change (<1 cm) from preoperative were found to be smaller, had less preoperative tendon retraction, had less preoperative MTJ medialization, and had less preoperative rotator cuff fatty infiltration (P <.05). Conclusions Preoperative MTJ medialization, tendon retraction, and muscle quality are all predictive of tendon healing postoperatively when using a single-row rotator cuff repair technique. The position of the MTJ with respect to the glenoid face can be predictive of healing, with over 90% healing if lateral and 50% if medial to the face. Lengthening of the tendon accounts for a significant percentage of the musculotendinous unit lengthening that occurs in healed tears as opposed to muscle elongation. Level of Evidence Level IV, therapeutic case series.
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