Current biomechanical concepts for rotator cuff repair

Abstract

For the past few decades, the repair of rotator cuff tears has evolved significantly with advances in arthroscopy techniques, suture anchors and instrumentation. From the biomechanical perspective, the focus in arthroscopic repair has been on increasing fixation strength and restoration of the footprint contact characteristics to provide early rehabilitation and improve healing. To accomplish these objectives, various repair strategies and construct configurations have been developed for rotator cuff repair with the understanding that many factors contribute to the structural integrity of the repaired construct. These include repaired rotator cuff tendon-footprint motion, increased tendon-footprint contact area and pressure, and tissue quality of tendon and bone. In addition, the healing response may be compromised by intrinsic factors such as decreased vascularity, hypoxia, and fibrocartilaginous changes or aforementioned extrinsic compression factors. Furthermore, it is well documented that torn rotator cuff muscles have a tendency to atrophy and become subject to fatty infiltration which may affect the longevity of the repair. Despite all the aforementioned factors, initial fixation strength is an essential consideration in optimizing rotator cuff repair. Therefore, numerous biomechanical studies have focused on elucidating the strongest devices, knots, and repair configurations to improve contact characteristics for rotator cuff repair. In this review, the biomechanical concepts behind current rotator cuff repair techniques will be reviewed and discussed.

Keywords: Biomechanics; Load to failure; Rotator cuff repair; Transosseous-equivalent.

Fig. 1

Supraspinatus repair being loaded with an Instron material testing machine in 30 degrees of abduction.

Fig. 2

Typical materials testing load deformation curve for cyclic loading (cycle 1) and load to failure with relevant parameters.

Fig. 3

Single-row supraspinatus rotator cuff repair with two anchor locations placed at the lateral edge of the tendon footprint and simple sutures passed through the torn tendon edge. (A) Anchor locations and (B) final repair.

Fig. 4

Original double-row supraspinatus repair with a medial row of suture anchors placed just lateral to the articular margin and the lateral row of suture anchors placed just medial to the "drop off" of the greater tuberosity. (A) Anchor locations and (B) final repair.

Fig. 5

Transosseous-equivalent supraspinatus repair developed by Park, et al. Compared to the original double-row repair, the lateral row of anchors is placed distally, allowing tensioning of the suture bridge that provides compression between the tendon and bone. (A) Anchor locations and (B) final repair.