Hatta, Taku

ABSTRACTSurgical repair is a common treatment for rotator cuff tear; however, the retear rate is high. A high degree of suture repair strength is important to ensure rotator cuff integrity for healing. The purpose of this study was to compare the mechanical performance of rotator cuffs repaired with a mesh suture versus traditional polydioxanone suture II and FiberWire sutures in a canine in vitro model. Seventy‐two canine shoulders were harvested. An infraspinatus tendon tear was created in each shoulder. Two suture techniques—simple interrupted sutures and two‐row suture bridge—were used to reconnect the infraspinatus tendon to the greater tuberosity, using three different suture types: Mesh suture, polydioxanone suture II, or FiberWire. Shoulders were loaded to failure under displacement control at a rate of 20 mm/min. Failure load was compared between suture types and techniques. Ultimate failure load was significantly higher in the specimens repaired with mesh suture than with polydioxanone suture II or FiberWire, regardless of suture technique. There was no significant difference in stiffness among the six groups, with the exception that FiberWire repairs were stiffer than polydioxanone suture II repairs with the simple interrupted technique. All specimens failed by suture pull‐out from the tendon. Based on our biomechanical findings, rotator cuff repair with the mesh suture might provide superior initial strength against failure compared with the traditional polydioxanone suture II or FiberWire sutures. Use of the mesh suture may provide increased initial fixation strength and decrease gap formation, which could result in improved healing and lower re‐tear rates following rotator cuff repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:987–992, 2018.

ABSTRACTIntroduction: Rotator cuff (RC) tears result in muscle atrophy and fat infiltration within the RC muscles. An estimation of muscle quality and deformation, or extensibility, is useful in selecting the most appropriate surgical procedure. We determined if noninvasive quantitative assessment of intramuscular fat using MRI could be used to predict extensibility of the supraspinatus muscle. Methods: Seventeen cadaveric shoulders were imaged to assess intramuscular fat infiltration. Extensibility and histological evaluations were then performed. Results: Quantitative fat infiltration positively correlated with histological findings and presented a positive correlation with muscle extensibility (r = 0.69; P = 0.002). Extensibility was not significantly different between shoulders graded with a higher fat content versus those with low fat when implementing qualitative methods. Discussion: A noninvasive prediction of whole‐muscle extensibility may directly guide pre‐operative planning to determine if the torn edge could efficiently cover the original footprint while aiding in postoperative evaluation of RC repair. Muscle Nerve 57: 129–135, 2018

Purpose To investigate the alteration of passive stiffness in the supraspinatus muscle after double‐row (DR) and knotless transosseous‐equivalent (KL‐TOE) repair techniques, using shear wave elastography (SWE) in cadavers with rotator cuff tears. We also aimed to compare altered muscular stiffness after these repairs to that obtained from shoulders with intact rotator cuff tendon. Methods Twelve fresh‐frozen cadaveric shoulders with rotator cuff tear (tear size: small [6], medium‐large [6]) were used. Passive stiffness of 4 anatomic regions in the supraspinatus muscle was measured based on an established SWE method. Each specimen underwent DR and KL‐TOE footprint repairs at 30° glenohumeral abduction. SWE values, obtained at 0°, 10°, 20°, 30°, 60°, and 90° abduction, were assessed in 3 different conditions: preoperative (torn) and postoperative conditions with the 2 techniques. The increased ratio of SWE values after repair was compared among the 4 regions to assess stiffness distribution. In addition, SWE values were obtained on 12 shoulders with intact rotator cuff tendons as control. Results In shoulders with medium‐large‐sized tears, supraspinatus muscles showed an increased passive stiffness after rotator cuff repairs, and this was significantly observed at adducted positions. KL‐TOE repair showed uniform stiffness changes among the 4 regions of the supraspinatus muscle (mean, 189% to 218% increase after repair), whereas DR repair caused a significantly heterogeneous stiffness distribution within the muscle (mean, 187% to 319% after repair, P = .002). Although a repair‐induced increase in muscle stiffness was observed also in small‐sized tears, there were no significant differences in repaired stiffness changes between DR and KL‐TOE (mean, 127% to 138% and 127% to 130% after repairs, respectively). Shoulders with intact rotator cuff tendon showed uniform SWE values among the 4 regions of the supraspinatus muscle (mean, 38.2 to 43.0 kPa). Conclusions Passive stiffness of the supraspinatus muscle increases after rotator cuff repairs for medium‐large‐sized tears. KL‐TOE technique for the medium‐large‐sized tear provided a more uniform stiffness distribution across the repaired supraspinatus muscles compared with the DR technique. Clinical Relevance Based on this insight, investigating rotator cuff muscle stiffness changes, further studies using SWE may determine the optimal repair technique for various sizes of rotator cuff tears.