Influence of Rotator Cuff Tear Size and Repair Technique on the Creation and Management of Dog Ear Deformities in a Transosseous-Equivalent Rotator Cuff Repair Model

Abstract

Background: Redundancies in the rotator cuff tissue, commonly referred to as "dog ear" deformities, are frequently encountered during rotator cuff repair. Knowledge of how these deformities are created and their impact on rotator cuff footprint restoration is limited.

Purpose: The goals of this study were to assess the impact of tear size and repair method on the creation and management of dog ear deformities in a human cadaveric model.

Study design: Controlled laboratory study.

Methods: Crescent-shaped tears were systematically created in the supraspinatus tendon of 7 cadaveric shoulders with increasing medial to lateral widths (0.5, 1.0, and 1.5 cm). Repair of the 1.5-cm tear was performed on each shoulder with 3 methods in a randomized order: suture bridge, double-row repair with 2-mm fiber tape, and fiber tape with peripheral No. 2 nonabsorbable looped sutures. Resulting dog ear deformities were injected with an acrylic resin mixture, digitized 3-dimensionally (3D), and photographed perpendicular to the footprint with calibration. The volume, height, and width of the rotator cuff tissue not in contact with the greater tuberosity footprint were calculated using the volume injected, 3D reconstructions, and calibrated photographs. Comparisons were made between tear size, dog ear measurement technique, and repair method utilizing 2-way analysis of variance and Student-Newman-Keuls multiple-comparison tests.

Results: Utilizing 3D digitized and injection-derived volumes and dimensions, anterior dog ear volume, height, and width were significantly smaller for rotator cuff repair with peripheral looped sutures compared with a suture bridge (P < .05) or double-row repair with 2-mm fiber tape alone (P < .05). Similarly, posterior height and width were significantly smaller for repair with looped peripheral sutures compared with a suture bridge (P < .05). Dog ear volumes and heights trended larger for the 1.5-cm tear, but this was not statistically significant.

Conclusion: When combined with a standard transosseous-equivalent repair technique, peripheral No. 2 nonabsorbable looped sutures significantly decreased the volume, height, and width of dog ear deformities, better restoring the anatomic footprint of the rotator cuff.

Clinical relevance: Dog ear deformities are commonly encountered during rotator cuff repair. Knowledge of a repair technique that reliably decreases their size, and thus increases contact at the anatomic footprint of the rotator cuff, will aid sports medicine surgeons in the management of these deformities.

Keywords: FiberLink; SpeedBridge; SutureBridge; digitization; dog ear deformity; rotator cuff repair.

Figure 1.

(A and B) Setup. The scapula is clamped, soft tissues dissected, and a suture/pulley construct used to maintain constant tension on the rotator cuff.

Figure 2.

Traction sutures through the edge of the cuff “tear” passed from lateral to medial through the 7-mm hole.

Figure 3.

Creating a dam. A tissue forceps is used to create a dam 1.6 cm medial to the edge of the footprint to prevent the acrylic resin from extruding into the joint.

Figure 4.

Lateral row anchors were inserted 1.5 cm lateral to the rotator cuff footprint, spaced 1 cm apart.

Figure 5.

SpeedBridge with peripheral looped FiberLink repair.

Figure 6.

(A) Digitizing the rotator cuff. (B) Digitized rotator cuff. An unsmoothed representation of the rotator cuff and dog ears. (C) Smoothed 3-dimensional digitization. Surface curves were traced, lofted, and smoothed with Rhinoceros software.

Figure 7.

Calibrated photograph.

Figure 8.

(A) Dog ear volume, (B) height, and (C) width. Volume, height, and width trended larger for the 1.5-cm tear, but there was no significant difference.

Figure 9.

Dog ear volume. Anterior dog ear volume was significantly smaller for repair with FiberLink compared with SutureBridge or SpeedBridge alone. *Significant difference.