Tear Completion Versus In Situ Repair for 50% Partial-Thickness Bursal-Side Rotator Cuff Tears: A Biomechanical and Histological Study in an Animal Model

Abstract

Background: Tear completion followed by repair (TCR) and in situ repair (ISR) have been widely used for bursal-side partial-thickness rotator cuff tears (PTRCTs). Both techniques have shown favorable results; however, controversy continues in terms of the best management. Purpose: To compare the histological and biomechanical outcomes of these 2 techniques for 50% partial-thickness bursal-side rotator cuff tear repair in a rabbit model. Study Design: Controlled laboratory study. Methods: A total of 27 rabbits were used in this experimental study. Seven rabbits were sacrificed at the beginning of the study to form an intact tendon control group. A chronic 50% partial-thickness bursal-side tear model was created in 20 rabbits, and 5 rabbits were sacrificed for biomechanical testing of chronic partial-thickness tears (control group) without repair. In 15 rabbits, partial-thickness tears were repaired after 8 weeks. Partial-thickness tears in the right shoulders were completed to full thickness and repaired; in contrast, left shoulders were repaired in situ. All rabbits were euthanized 8 weeks after the repair. The tendons were tested biomechanically for ultimate failure, linear stiffness, and displacement. Histological evaluations of tendon-to-bone healing were performed via the modified Watkins score. Results: Macroscopically, all repaired tendons were attached to the greater tuberosity. The TCR group had a higher failure load than the ISR group, with mean values of 140.4 ± 13.8 N and 108.1 ± 16.6 N, respectively ( P = .001). The modified Watkins score was significantly higher in the TCR group (23.5; range, 22-27) than in the ISR group (19.5; range, 16-22) ( P = .009). Conclusion: Both repair techniques are effective for 50% partial-thickness bursal-side rotator cuff tears; however, TCR yields significantly superior biomechanical and histological characteristics compared with ISR. Clinical Relevance: Tear completion and repair technique may increase tendon-to-bone healing and thereby reduce re-rupture rate in the partial thickness bursal side rotator cuff tears.

Arthroscopic Single Lateral Row Repair Technique for Small Rotator Cuff Tears

“…Interestingly, there have been studies on live animals that seem to show that tear completion and repair of partial-thickness rotator cuff tears provide better healing compared with in situ repair, in rabbits 30 and in rats. 31 We believe that the technique described here represents a reproducible and effective method in addressing small rotator cuff tears in which the bony footprint of the tendon is small, not visible at all, or covered with remnant tendon, and hence medial row anchors are not required.…”

“…Interestingly, there have been studies on live animals that seem to show that tear completion and repair of partial-thickness rotator cuff tears provide better healing compared with in situ repair, in rabbits 30 and in rats. 31 …”

The Biomechanical and Histological Processes of Rerouting Biceps to Treat Chronic Irreparable Rotator Cuff Tears in a Rabbit Model

“…After 2 months, 29,34 the biceps rerouting technique was performed in rabbits with chronic IRCT, modified from the reported clinical techniques. 14,16,32 Briefly, the skin and the deltoid were sequentially split through the previous incision, and a large V-shaped defect was exposed when the scar tissue and tagged sutures were removed (Figure 3A).…”

H-loop Knotless Double-Row Repair Versus Knotted Suture Bridge for Rotator Cuff Tears: A Biomechanical and Histological Study in an Animal Model

“…50 After loading, ultimate load to failure at the speed of 1 mm/s was performed to calculate the maximum pullout force. 39 Stiffness was defined according to the slope following the toe region using linear least squares regression analysis. 31…”