Improved strength of early versus late supraspinatus tendon repair: a study in the rabbit.

Abstract

The optimal timing for surgical repair of the supraspinatus (SSP) tendon after full-substance tear has not been established. The objectives of this prospective investigation of SSP tendon repair delayed by 1, 2, or 3 months followed by a 3-month postoperative course were to (1) determine the site of failure, (2) measure the tensile strength and stiffness, and (3) assess the ability of computed tomography to predict mechanical strength. We transected 1 SSP tendon in 36 rabbits and then repaired it with transosseous sutures after a delay of 1, 2, or 3 months. We compared the results with 36 intact shoulders from 18 age-matched control rabbits. Experimental specimens failed at the tendon (n = 26) more often than at the enthesis (n = 10) (P < .05). The mean peak loads to failure 3 months after repair delayed by 1 month and delayed by 2 months were significantly greater than their respective control values (P < .05 for both); there was no difference after a delay of 3 months. There was no association between the presence of hypoattenuation on computed tomography and repair strength (P > .05). Our findings indicate better mechanical results with earlier repair (1 or 2 months) after SSP tendon than after a delay of 3 months. Early surgical repair may lower the risk of tendon retear.