In Vivo Static Retraction and Dynamic Elongation of Rotator Cuff Repair Tissue After Surgical Repair: A Preliminary Analysis at 3 Months.

Background: Rotator cuff repair is a common orthopaedic procedure that provides pain relief for many patients, but unfortunately, an estimated 20% to 70% of repair procedures will fail. Previous research has shown that elongation (ie, retraction) of a repaired tendon is common even in patients with a repair construct that appears intact on magnetic resonance imaging. However, it is unknown how this repair tissue functions under dynamic conditions.
Purpose: To quantify static retraction and maximum dynamic elongation of repair tissue after rotator cuff repair.
Study Design: Case series; Level of evidence, 4.
Methods: Data from 9 patients were analyzed for this study. During surgery, a 3.1-mm tantalum bead was sutured to the supraspinatus tendon, medial to the repair site. Glenohumeral kinematics were assessed at 1 week (static) and 3 months (static and during scapular-plane abduction) after surgery using a biplanar videoradiographic system. The 3-dimensional position of the bead was calculated relative to the tendon's insertion on the humerus (ie, bead-to-insertion distance). Static retraction was calculated as the change in the bead-to-insertion distance under static conditions between 1 week and 3 months after surgery, and maximum dynamic elongation was calculated as the maximal positive change in the bead-to-insertion distance during dynamic motion relative to the start of motion. The magnitudes of static retraction and maximum dynamic elongation were assessed with 1-sample t tests.
Results: At 3 months after surgery, static retraction occurred in all patients by a mean of 10.0 ± 9.1 mm ( P = .01 compared with no elongation). During scapular-plane abduction, maximum dynamic elongation averaged 1.4 ± 1.0 mm ( P < .01 compared with no elongation). Descriptively, dynamic elongation consistently took 1 of 2 forms: an initial increase in the bead-to-insertion distance (mean, 2.0 ± 0.6 mm) before decreasing until the end of motion or an immediate and substantial decrease in the bead-to-insertion distance at the onset of motion.
Conclusion: Repair tissue elongation (static retraction and maximum dynamic elongation) appeared to be a common and significant finding at 3 months after arthroscopic rotator cuff repair. Dynamic elongation of repair tissue during scapular-plane abduction exhibited 1 of 2 distinct patterns, which may suggest different patterns of supraspinatus mechanical and neuromuscular function.
Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: Research reported in this article was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (award No. R01AR051912). V.M. has received education payments from Arthrex, consulting fees from Pacira Pharmaceuticals, and hospitality payments from Smith & Nephew and Stryker. E.C.M. has received education payments from Arthrex, consulting fees from Endo Pharmaceuticals and Smith & Nephew, and speaking fees from Smith & Nephew. S.M. has received education payments from Arthrex; consulting fees from DePuy/Medical Device Business Services, Exactech, and FX Shoulder USA; and hospitality payments from Smith & Nephew. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
(© The Author(s) 2022.)