Relative Fixation Strength of Rabbit Subscapularis Repair Is Comparable to Human Supraspinatus Repair at Time 0

Abstract

Background Recent evidence suggests that the rabbit subscapularis tendon may be anatomically, biomechanically, and histologically suitable to study rotator cuff pathology and repair. However, biomechanical comparisons of rotator cuff repairs in this model have not been evaluated and compared to those in human cadaveric specimens. Questions/purposes We quantified the biomechanical properties of the repaired rabbit subscapularis tendon after (1) single-row, (2) double-row, and (3) transosseousequivalent rotator cuff repair techniques and compared the ratios of repairs to previously published data for human repairs.Methods Tensile testing was performed on 21 New Zealand White rabbit subscapularis tendon-humerus complexes for single-row repair, double-row repair, and transosseous-equivalent repair (n = 7 for each group). Video digitizing software was used to quantify deformation. Load elongation data were then used to quantify structural properties. We compared the ratios of rotator cuff repairs for the rabbit data to data from human supraspinatus repair studies previously performed in our laboratory. For our primary end points (linear stiffness, yield load, ultimate load, and energy absorbed to failure), with the numbers available, our statistical power to detect a clinically important difference (defined as 15%) was 85%. Results The ratios of single-row/double-row repair were 0.72, 0.73, 0.71, and 0.66 for human supraspinatus and 0.77, 0.74, 0.79, and 0.89 for rabbit subscapularis repair for linear stiffness, yield load, ultimate load, and energy absorbed to failure, respectively. The ratios of double-row/transosseousequivalent repair were 1.0, 0.86, 0.70, and 0.41 for human supraspinatus and 1.22, 0.85, 0.76, and 0.60 for rabbit subscapularis for linear stiffness, yield load, ultimate load, and energy absorbed to failure, respectively. There were no differences comparing rabbit to human repair ratios for any parameter (p [ 0.09 for all comparisons). Conclusions Subscapularis repairs in the rabbit at Time 0 result in comparable ratios to human supraspinatus repairs. Clinical Relevance The biomechanical similarities between the different types of rotator cuff repair in the rabbit subscapularis and human supraspinatus at Time 0 provide more evidence that the rabbit subscapularis may be an appropriate model to study rotator cuff repairs.

Postoperative malrotation of humerus shaft fracture causes degeneration of rotator cuff and cartilage

“…Thus, rabbits were considered a suitable animal model to research rotator cuff pathology, especially that caused by extrinsic factor alterations (e.g., biomechanical changes) 22 . In recent years, rabbit models have been extensively applied in rotator cuff repair research 23 – 27 .…”

Mechanical Properties of Animal Tendons: A Review and Comparative Study for the Identification of the Most Suitable Human Tendon Surrogates

“…For example, the rat model developed by Soslowsky et al [6] is considered as the most suitable rotator cuff model due to its similarity to human anatomy (the presence of an acromial arch) and its range of motion [5]. The determination of the most suitable animal rotator cuff model allows for in vivo simulation to analyze different factors affecting the repair process, thus improving the therapeutic process [7]. Several studies dealing with tissue reconstruction via suture patterns or scaffolds used animal specimens to perform tests, especially horse [8], dog [9], and swine [10] tendons.…”

Development of a Rabbit Chronic-Like Rotator Cuff Injury Model for Study of Fibrosis and Muscular Fatty Degeneration

“…(3) transosseous-equivalent RC repair techniques, and found that the initial biomechanical characteristics of these repairs were similar to human SSP RC repairs performed in cadaveric specimens 12 . As such, the anatomical, physiological, and biomechanical similarity of rabbit SSC with human SSP makes it useful for modeling RC injuries.…”