Tears of the rotator cuff tendons are a very common entity. Despite recent advances in arthroscopic rotator cuff repair, the re-tear rate remains high. Thus, new methods to improve healing rates following rotator cuff repair must be sought. The purpose of this prospective randomized double-blind controlled study is to compare the functional outcomes and healing rates of an adjuvant pre-operative bone microfracture technique prior to arthroscopic cuff repair.

Patients undergoing arthroscopic rotator cuff repair were randomized to receive either a percutaneous bone microfracture of the supraspinatus footprint or a “soft tissue needling” technique, in which the pin was passed through the peripheral edges of the rotator cuff, five-seven days prior to index surgery, under ultrasound guidance. Follow-ups were completed at 3, 6, 12 and 24 months post-operatively. Healing status was determined by ultrasound at 6 and 24 months. The primary objective was to compare the WORC score at 24 months. Secondary objectives included the healing status via ultrasound, the Constant, and the ASES scores. A sample size calculation determined that 90 patients provided 80% power to detect a statistical difference between groups.

Baseline demographic data did not differ between groups. No statistical differences were detected in the WORC outcome at any time points (p=0.47, baseline, p=0.60, 3 months, p=0.79, 6 months, p=0.50, 12 months, p=0.54, 24 months). Healing rates did not differ between groups (P=0.34) and no differences were observed in the ASES or Constant Scores at all time-points. Statistically significant improvements occurred in both groups from baseline to all time points in all clinical outcome scores (p < 0 .0001).

No statistically significant differences in primary or secondary outcomes were identified between pre-operative bone microfracture and soft tissue needling techniques prior to arthroscopic rotator cuff repair. This study does not support pre-operative microfracture as a adjuvant technique prior to arthroscopic cuff repair.

Objectives

Although many clinical and experimental investigations have shed light on muscle atrophy and intramuscular accumulation of fat after rotator cuff disruption, none have reported on their onset in the absence of muscle retraction.

The purpose of this study was to clarify the effect of delay of the reattachment of the supraspinatus tendon into a bony trough to the strength of the repaired tendon-bone complex. The supraspinatus tendon of rabbits were transected and reattached into bony troughs at the greater tuberosity immediately and six weeks after transection. The tensile strength of the tendon-bone complex, harvested twelve weeks after reattachment, were measured.

The tensile strength showed no difference between immediate and delayed reattached shoulders. Six weeks delay of supraspinatus tendon repair seems not to weaken the tensile strength of repaired tendon-bone complex.

The purpose of this study was to clarify the effect of timing of surgery on the strength of the supraspinatus tendon-bone complex after the reimplantation of the tendon into a bony trough.

In eight rabbits, the supraspinatus tendon was transected and reinserted into a bony trough at the greater tuberosity (early reattachment group). In seven rabbits, the supraspinatus tendon was reinserted six weeks after transection (delayed reattachment group). In both groups, the rabbits were sacrificed twelve weeks after reattachment, and the tensile strength of the tendon-bone complex was measured. The contralateral shoulders served as controls.

None of the operated tendons failed at the site of reimplantation. The ratio of tensile strength of the operated tendon-bone complex to the controls showed no difference between two groups (Immediate reattachment group: 79.9± 1 S.E. 16.5%, delayed reattachment group: 80.4± 12.6%, P> 0.05).

This is the first experimental study to compare the tensile strength of supraspinatus tendon-bone complex repaired after different time intervals.

Stress-shielded tendon & bone tend to decrease their tensile strength. Given the six weeks duration of detachment, a weaker tensile strength of delayed reattachment group was expected than of the early reattachment group. The fact that both groups did not show a difference might be due to the recovery of tensile strength of tendon & bone in twelve weeks after reattachment.

Six weeks delay of repair of supraspinatus tendon does not weaken the tensile strength of repaired tendon-bone complex.

Fundings This study has been supported in part by a grant from the American Shoulder and Elbow Surgeons.