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Abstract Presented at the 29th Annual Meeting of the Arthroscopy Association of North America| Volume 26, ISSUE 6, SUPPLEMENT , e2-e3, June 01, 2010

Measurement of Rotator Cuff Tension In Vivo: Single-row vs Double-row Repair (SS-04)

      Introduction

      The merits of single-row vs. double-row rotator cuff repair constructs have been debated in recent years. Some authors suggest that double-row constructs are biomechanically superior and provide restoration of the footprint of the rotator cuff. Others have suggested that the laterally based double row repair places significantly higher tension on the construct compared to a medially based single-row repair. The purpose of this research was to report the difference in rotator cuff tension between medially based articular margin single-row repairs compared to laterally based double-row repairs in vivo.

      Methods

      Patients with rotator cuff tears undergoing arthroscopic rotator cuff repair at a single institution were identified. After diagnostic arthroscopy, the rotator cuff tear is debrided back to normal, healthy tissue, and adhesions to the bursa or labrum are removed. The tear size is measured in the anterior-posterior and medial-lateral planes using a pre-measured marked suture. A tissue grasper is then placed onto the apex of the tear through the lateral portal. A calibrated digital weigh scale is then attached. The tendon edge is then pulled just lateral to the articular margin, simulating the location of a medially based single row repair, and the tension is recorded. Next, the tendon edge is pulled laterally to the edge of the greater tuberosity, simulating its final location after a double row repair, and the tension is recorded. All measurements are made with the arm abducted 20 degrees, simulating the position of post-operative sling immobilization.

      Results

      Twenty-one rotator cuff tears were available for measurement. 16 were crescent tears. 3 were L-shaped and 2 were bursal sided partial tears that required completion of the tear. The average AP tear size was 18.1 mm. The average ML tear size was 19.7 mm. The mean cuff tension when the tendon edge was approximated to the articular margin was 0.41 lb. The mean cuff tension when approximated to the lateral greater tuberosity was 2.16 lb. This is a 5.2 fold difference (p<0.000001). Sub-group analysis was done for small (<=20 mm ML) vs. large tears (>20 mm ML) tears. For the smaller tears, the average tension to the articular margin was 0.28 lb. The average tension to the lateral tuberosity was 1.73 lb for a 6.3 fold difference (p<0.0005). For the larger tears, the average tension to the articular margin was 0.63 lb. The average tension to the lateral tuberosity was 2.84 lb. This was a 4.5 fold difference (p<0.0005). When comparing the tension at the articular margin between small and large tears (0.28 vs 0.63 lbs), a difference was noted (p<0.01). Significance was also achieved when comparing the tensions at the lateral tuberosity (p<0.04) between small and large tears (1.73 vs. 2.84 lbs).

      Conclusion

      This study demonstrates a significant 5-fold difference in the amount of tension the rotator cuff tendon experiences under medially-based single and laterally-based double-row constructs at the time of repair. Larger, retracted tears >2 cm require significantly more tension to reapproximate to both the articular margin and lateral tuberosity.