A Biomechanical Comparison of Shoulder Rotation and Cyclic Loading Between Single Row, Triple Loaded Cuff Repairs and Double Row, Suture Tape Cuff Repairs Using Biocomposite Anchors (SS‐20)

IntroductionPurpose: to compare shoulder rotation and cyclic loading in a single row, triple loaded anchor repair with a suture-tape, rip-stop, double row rotator cuff repair.MethodsUsing 18 human shoulders from 9 matched cadaver pairs, two groups of rotator cuff repairs were created. Group 1 was a double row, rip stop, suture tape construct. Group 2 was a single row, triple loaded construct. Prior to mechanical testing, the supraspinatus footprint was measured using calipers. A superiorly positioned digital camera optically measured the tendon footprint motion during 60° of humeral internal and external rotation. Specimens were secured at a fixed angle not exceeding 45° in reference to the load. After preloading, each sample was cycled between 10N and 100N for 200 cycles at 1Hz followed by destructive testing at 33mm/sec. A digital camera with tracking software measured the repair displacement at 100 and 200 cycles. Ultimate load and failure mode for each sample was recorded.ResultsResults: Group 1's exposed anterior footprint border (6.5%±6) and posterior footprint border (0.9%±1.7) were statistically less than Group 2's exposed anterior footprint border (30.3%±17) and posterior footprint border (29.8%±14) (p= 0.003 and p< 0.001 respectively). The Group 1 maximal internal (IR) and external (ER) tendon footprints displacement (1.6mm and 1.4mm respectively) was less than Group 2 (both 3.6mm) (p=0.007 and p=0.004 respectively). Average displacement after 100 cycles for Group 1 and Group 2 was 2.0mm and 3.2mm respectively and at 200 cycles 2.5mm and 4.2mm respectively (p=0.02). Mean Group 1 ultimate failure load (586N) was greater than that of Group 2 (393N) (p=0.02). The suture tendon interface was the site of most construct failures.ConclusionConclusions: The suture-tape, rip-stop, double row rotator cuff repair had greater footprint coverage, less rotational footprint displacement, and greater mean ultimate failure load than a triple loaded, single row repair in mechanical testing. No double row or single row constructs demonstrated 5 mm of displacement after the first 100 cycles. Clinical Relevance: Differences in cuff fixation influence rotational tendon movement and may influence postoperative healing. Stronger repair constructs still fail at the suture tendon interface. IntroductionPurpose: to compare shoulder rotation and cyclic loading in a single row, triple loaded anchor repair with a suture-tape, rip-stop, double row rotator cuff repair.