Rotator Cuff Repair Techniques Research Articles

Healing disturbance with suture bridge configuration repair in rabbit rotator cuff tear

Medial row failure has been reported in the suture bridge technique of rotator cuff repair. This study compared the healing response of suture bridge configuration repair (SBCR) and parallel type transosseous repair (PTR). Acute rotator cuff repair was performed in 32 rabbits. Both shoulders were repaired using PTR or SBCR. In PTR, simple PTR was performed through 2 parallel transosseous tunnels created using a microdrill. In SBCR, 2 additional crisscross transosseous tunnels were added to mimic arthroscopic SBCR. At 1, 2, and 5 weeks postoperatively, comparative biomechanical testing was performed in 8 rabbits, and histologic analysis, including immunohistochemical staining for CD31, was performed in 4 rabbits. Failure loads at 1 week (38.12 ± 20.43 N vs 52.00 ± 27.23 N; P = .284) and 5 weeks (97.93 ± 48.35 N vs 119.60 ± 60.81 N; P = .218) were not statistically different between the SBCR and PTR groups, respectively, but were significantly lower in the SBCR group than in the PTR group (23.56 ± 13.56 N vs. 44.25 ± 12.53 N; P = .009), respectively, at 2 weeks. Markedly greater fibrinoid deposition was observed in the SBCR group than in the PTR group at 2 weeks. For vascularization, there was a tendency that more vessels could be observed in PTR than in SBCR at 2 weeks (15.9 vs 5.6, P = .068). In a rabbit acute rotator cuff repair model, SBCR exhibited inferior mechanical strength, and fewer blood vessels were observed at the healing site at 2 weeks postoperatively. Medial row tendon failure was more common in SBCR. Surgeons should consider the clinical effect of SBCR when performing rotator cuff repair.

Arthroscopic Rotator Cuff Repair Using the Undersurface Technique: A 2-Year Comparative Study in 257 Patients.

Background:Arthroscopic rotator cuff repair has traditionally been performed in the subacromial space from the bursal side of the tendon. The undersurface rotator cuff repair technique involves the arthroscope remaining in the glenohumeral joint, thus viewing the tendon from its undersurface during repair without a bursectomy or acromioplasty.Purpose:To compare the clinical and structural outcomes of undersurface rotator cuff repair with bursal-side repair.Study Design:Cohort study; Level of evidence, 3.Methods:A retrospective analysis of prospectively collected data was conducted on 2 cohorts of patients who had undergone arthroscopic rotator cuff repair with knotless suture anchors configured in a single-row formation using inverted mattress–style sutures from either the bursal side (n = 100) or undersurface (n = 165) of the supraspinatus tendon. Data were collected preoperatively, intraoperatively, and at 1 week, 6 weeks, 3 months, 6 months, and 2 years postoperatively. At each time point, patients completed a modified L’Insalata questionnaire to assess patient-ranked pain scores and were clinically examined using standardized tests. Ultrasound examination was performed at 6 months and 2 years to assess the integrity of the repair.Results:At 2 years postoperatively, patients in both cohorts had significantly less pain and less difficulty with overhead activities compared with preoperative levels (P < .001). The type of repair performed (bursal or undersurface) did not affect the ability to perform overhead activities at 2 years. At 2 years, both groups also had similar retear rates (21% for bursal side, 23% for undersurface). The mean operative time for the arthroscopic rotator cuff repair was 32 minutes when performed from the bursal side and 20 minutes when performed from the undersurface (P < .001).Conclusion:Arthroscopic rotator cuff repair, whether performed from the subacromial space or glenohumeral joint, resulted in decreased levels of pain and difficulty with overhead activities at 2 years. The major difference between the 2 techniques was operative time, with the undersurface technique being performed significantly faster than the bursal-side repair technique.

Footprint Contact Area and Interface Pressure Comparison Between the Knotless and Knot-Tying Transosseous-Equivalent Technique for Rotator Cuff Repair

To quantify and compare the footprint contact area and interface pressure on the greater tuberosity between knotless and knot-tying transosseous-equivalent (TOE) repair using pressure-sensitive film. We used 11 pairs of fresh-frozen cadaveric shoulders (22 specimens), in which rotator cuff tears were created before repair. Each pair was randomized to either conventional medial knot-tying TOE repair (group A) or medial knotless TOE repair using the modified Mason-Allen technique (group B). Pressure-sensitive film was used to quantify the pressurized contact area and interface pressure between the greater tuberosity and supraspinatus tendon. The mean pressurized contact area was 33.2 ± 2.5 mm(2) for group A and 28.4 ± 2.4 mm(2) for group B. There was a significant difference between groups (P=.005). Although the overall contact configuration of both groups was similar and showed an M shape, group A showed a greater pressurized configuration around the medial row. The mean interface pressure was 0.20 ± 0.02 MPafor group A and 0.17 ± 0.02 MPa for group B. There was a significant difference between groups (P=.001). Contrary to our hypothesis, in this time-zero study, medial knotless TOE repair using a modified Mason-Allen suture produced a significantly inferior footprint contact area and interface pressure compared with conventional medial knot-tying TOE repair. Even though we found a statistically significant difference between the 2 repair methods, it is still unknown if this statistical difference seen in our study has any clinical and radiologic significance.

Platelet-rich Plasma in Arthroscopic Rotator Cuff Repair

Rotator cuff tear is a common reason for shoulder pain. Although the surgical technique of rotator cuff repair is developing, high retear rate requires additional supplementary methods. Among these supplementary methods, as a kind of biologic augmentation, platelet-rich plasma (PRP) has been spotlighted and has recently been studied by many researchers. PRP, a concentrate of platelet extract obtained from whole blood, contains numerous growth factors. As this is known to play an important role in the tissue recovery process, it had been used for research in a variety of fields including orthopedics. Use of PRP has been attempted in surgical treatments of rotator cuff tear for better results; however, only a few large-scale research studies on the effect of PRP have been reported. Clinical results of each study are also variable. Therefore research using large-scale randomized, double-blind trials should be conducted in order to prove the application range, safety, and clinical effects of PRP.

Current Biomechanical Concepts of Suture Bridge Repair Technique for Rotator Cuff Tear

Rotator cuff tears are one of the most common disorders of the shoulder and can have significant effects on daily activities as a result of pain, loss of motion and strength. The goal of rotator cuff repair is aimed at anatomic restoration of the rotaotr cuff tendon to reduce pain and improve the joint function. Recently, arthroscopic repair has been widely accepted for treatment of rotator cuff tears due to its equal or better results than those from open repair. In 2006, a transosseous-equivalent (TOE) or technique was introduced by Park et al. This technique maximizes the utility of the conventional double-row technique by using the suture limbs to form the medial mattress sutures to bridge and compress the repaired tendon. This technique has been proven to provide biomechanical properties that are superior to other arthroscopic repair techniques regarding the initial fixation strength, contact area and contact pressure at the tendon-bone interface. Since suture bridge techniques have been envolving over time, further biomechanical investigations have been carried out. These studies include examination of the effect of dynamic humeral external rotation on the mechanical stability or the repaired tendon construct, the effects of various midifications of the suture bridge configurations on the biomechanical characteristics of the medial mattress suture, biomechanical implication of medial row failure, and biomechanical performance of the repaired construct over time. In this review, the biomechanical concepts behind the suture bridge technique for rotator cuff repair were reviewed and discussed.

The Simple Cow Hitch Stitch Technique for Arthroscopic Rotator Cuff Repair and Stabilization Using Knotless Suture Anchors

The tissue-suture interface is the most vulnerable and challenging part of adequate restoration and fixation in rotator cuff repair. We describe a simple stitch technique for arthroscopic rotator cuff repair using knotless suture anchors based on the cow hitch. The simple cow hitch stitch technique is easy to perform, especially under difficult conditions, and provides excellent initial fixation strength as required for integration of the reinserted cuff and for shoulder stabilization.

The temporal outcomes of open versus arthroscopic knotted and knotless rotator cuff repair over 5 years.

The present study aimed to determine how repair technique influenced structural and clinical outcomes at 5 years post-surgery. Three cohorts of patients had repair of a symptomatic rotator cuff tear using (i) an open double-row mattress repair technique (n = 25); (ii) arthroscopic single-row simple suture knotted technique (n = 25); or (iii) arthroscopic single-row inverted mattress knotless technique (n = 36) by one surgeon. Standardized patient- and examiner-determined outcomes were obtained pre-operatively and postoperatively with a validated protocol, ultrasound were also performed at the same time. Retear occurred more often after open repair (48%) at 5 years than after arthroscopic knotted (33%) and arthroscopic knotless (26%) repair. Retear was associated with increasing age, pre-operative tear size and weaker pre-operative and 5 years postoperative cuff strength. Between 2 years and 5 years, the open repair group experienced an increase in the frequency of pain during activity, as well as in the difficulty experienced and the severity of pain during overhead activities (p < 0.05) and, at 5 years, also experienced more difficulty with overhead activities, compared to the arthroscopic knotless repair group. At 5-year follow-up, arthroscopic rotator cuff repair techniques resulted in fewer retears and better outcomes compared to an open double-row technique.

Load to Failure and Stiffness: Anchor Placement and Suture Pattern Effects on Load to Failure in Rotator Cuff Repairs.

Background:Rotator cuff tendinopathy is a frequent cause of shoulder pain that can lead to decreased strength and range of motion. Failures after using the single-row technique of rotator cuff repair have led to the development of the double-row technique, which is said to allow for more anatomical restoration of the footprint.Purpose:To compare 5 different types of suture patterns while maintaining equality in number of anchors. The hypothesis was that the Mason-Allen–crossed cruciform transosseous-equivalent technique is superior to other suture configurations while maintaining equality in suture limbs and anchors.Study Design:Controlled laboratory study.Methods:A total of 25 fresh-frozen cadaveric shoulders were randomized into 5 suture configuration groups: single-row repair with simple stitch technique; single-row repair with modified Mason-Allen technique; double-row Mason-Allen technique; double-row cross-bridge technique; and double-row suture bridge technique. Load and displacement were recorded at 100 Hz until failure. Stiffness and bone mineral density were also measured.Results:There was no significant difference in peak load at failure, stiffness, maximum displacement at failure, or mean bone mineral density among the 5 suture configuration groups (P < .05).Conclusion:According to study results, when choosing a repair technique, other factors such as number of sutures in the repair should be considered to judge the strength of the repair.Clinical Relevance:Previous in vitro studies have shown the double-row rotator cuff repair to be superior to the single-row repair; however, clinical research does not necessarily support this. This study found no difference when comparing 5 different repair methods, supporting research that suggests the number of sutures and not the pattern can affect biomechanical properties.

Current Biomechanical Concepts of Suture Bridge Repair Technique for Rotator Cuff Tear

Rotator cuff tears are one of the most common disorders of the shoulder and can have significant effects on daily activities as a result of pain, loss of motion and strength. The goal of rotator cuff repair is aimed at anatomic restoration of the rotaotr cuff tendon to reduce pain and improve the joint function. Recently, arthroscopic repair has been widely accepted for treatment of rotator cuff tears due to its equal or better results than those from open repair. In 2006, a transosseous-equivalent (TOE) or "suture bridge" technique was introduced by Park et al. This technique maximizes the utility of the conventional double-row technique by using the suture limbs to form the medial mattress sutures to bridge and compress the repaired tendon. This technique has been proven to provide biomechanical properties that are superior to other arthroscopic repair techniques regarding the initial fixation strength, contact area and contact pressure at the tendon-bone interface. Since suture bridge techniques have been envolving over time, further biomechanical investigations have been carried out. These studies include examination of the effect of dynamic humeral external rotation on the mechanical stability or the repaired tendon construct, the effects of various midifications of the suture bridge configurations on the biomechanical characteristics of the medial mattress suture, biomechanical implication of medial row failure, and biomechanical performance of the repaired construct over time. In this review, the biomechanical concepts behind the suture bridge technique for rotator cuff repair were reviewed and discussed.

Shoulder and Rotator Cuff Repair: Single vs Double Row

Rotator cuff tears are a common cause of upper extremity pain and dysfunction. The purpose of this article is to briefly review the preoperative assessment of patients with rotator cuff tears, including history, physical examination, and imaging of the shoulder. Its emphasis is to outline both the single-row and double-row arthroscopic rotator cuff repair techniques. Although there is no universally accepted best technique for arthroscopic rotator cuff repair, a surgeon’s experience, patient’ expectation, and technical considerations—including available equipment, tissue quality, and the size of the tear—are key to the success of the repair. At the conclusion of the article, the general principles of postoperative rehabilitation are briefly discussed.

History of rotator cuff surgery.

Rotator cuff surgery is a rapidly evolving branch in orthopaedics, which has raised from a minor niche to a fully recognized subspecialty. This article summarizes its history, examining the development of its key principles and the technical advancements. Literature was thoroughly searched, and few senior surgeons were interviewed in order to identify the significant steps in the evolution of rotator cuff surgery. A wide variety of surgical options is available to reduce pain and restore function after rotator cuff tears. Rotator cuff repair surgical techniques evolved from open to arthroscopic and are still in development, with new fixation techniques and biological solutions to enhance tendon healing being proposed, tested in laboratory and in clinical trials. Although good or excellent results are often obtained, there is little evidence that the results of rotator cuff repair are improving with the decades. An overall high re-tear rate remains, but patients with failed rotator cuff repairs can experience outcomes comparable with those after successful repairs. Rotator cuff repair techniques evolve at a fast pace, with new solutions often being used without solid clinical evidence of superiority. It is necessary to conduct high-level clinical studies, in which data relating to anatomical integrity, patient self-assessed comfort and function, together with precise description of patient's condition and surgical technique, are collected. IV.

Vascularity alterations in different rotator cuff repair techniques using contrast-enhanced ultrasound

Contrast-enhanced ultrasound is a useful method to clarify visualization of vascular patterns in basic and clinical investigations. The purpose of this study is to clarify vascularity alterations in different rotator cuff repair techniques using contrast-enhanced ultrasound.

Arthroscopic Versus Mini-Open Rotator Cuff Repair: An Up-to-Date Meta-analysis of Randomized Controlled Trials

The aim of this meta-analysis was to compare the clinical outcomes of arthroscopic and mini-open rotator cuff repairs based on recently published Level I randomized controlled trials (RCTs). We systematically searched electronic databases to identify RCTs that compared arthroscopic and mini-open rotator cuff repairs from 1980 to October 2013. The clinical outcome scores, including the University of California, Los Angeles score and the Constant-Murley score, were converted to a common 100-point outcome score for further analysis. The results of the pooled studies were analyzed in terms of surgery time, weighted 100-point score, pain on a visual analog scale (VAS), and range of motion. Study quality was assessed and relevant data were extracted independently by 2 reviewers. Five RCTs, including 166 patients in the arthroscopic repair group and 163 patients in the mini-open repair group, were included in this meta-analysis. The results of the meta-analysis showed that there were no significant differences in surgery time (P = .11), weighted 100-point score (P = .65), VAS pain score (P = .87), or range of motion (P = .29 for forward flexion and P = .82 for external rotation). On the basis of current literature, no differences in surgery time, functional outcome score, VAS pain score, and range of motion were found at the end of follow-up between the arthroscopic and mini-open rotator cuff repair techniques. In addition, there was no significant difference in VAS pain score in the early phase between the 2 repairs. Level I, meta-analysis of Level I studies.

Reusing cadaveric humeri for fracture testing after testing simulated rotator cuff tendon repairs.

The financial cost of using human tissues in biomedical testing and surgical reconstruction is predicted to increase at a rate that is disproportionately greater than other materials used in biomechanical testing. Our first hypothesis is that cadaveric proximal humeri that had undergone monotonic failure testing of simulated rotator cuff repairs would not differ in ultimate fracture loads or in energy absorbed to fracture when compared to controls (i.e., bones without cuff repairs). Our second hypothesis is that there can be substantial cost savings if these cadaveric proximal humeri, with simulated cuff repairs, can be re-used for fracture testing. Results of fracture tests (conducted in a backwards fall configuration) and cost analysis support both hypotheses. Hence, the bones that had undergone monotonic failure tests of various rotator cuff repair techniques can be re-used in fracture tests because their load-carrying capacity is not significantly reduced.

The global percutaneous shuttling technique tip for arthroscopic rotator cuff repair.

Most arthroscopic rotator cuff repairs utilize suture passing devices placed through arthroscopic cannulas. These devices are limited by the size of the passing device where the suture is passed through the tendon. An alternative technique has been used in the senior author’s practice for the past ten years, where sutures are placed through the rotator cuff tendon using percutaneous passing devices. This technique, dubbed the global percutaneous shuttling technique of rotator cuff repair, affords the placement of sutures from nearly any angle and location in the shoulder, and has the potential advantage of larger suture bites through the tendon edge. These advantages may increase the area of tendon available to compress to the rotator cuff footprint and improve tendon healing and outcomes. The aim of this study is to describe the global percutaneous shuttling (GPS) technique and report our results using this method. The GPS technique can be used for any full thickness rotator cuff tear and is particularly useful for massive cuff tears with poor tissue quality. We recently followed up 22 patients with an average follow up of 32 months to validate its usefulness. American Shoulder and Elbow Surgeons scores improved significantly from 37 preoperatively to 90 postoperatively (P<0.0001). This data supports the use of the GPS technique for arthroscopic rotator cuff repair. Further biomechanical studies are currently being performed to assess the improvements in tendon footprint area with this technique.

Surface-holding repair: an original arthroscopic rotator cuff repair technique

Arthroscopic rotator cuff repair provides satisfactory results; however, there is still a high rate of re-tear. The objective of this study was to present a surface-holding technique that we recently developed for arthroscopic rotator cuff repair in detail and to evaluate the clinical outcome as well as cuff repair integrity with this new method. A consecutive series of 116 patients with full-thickness rotator cuff tears underwent arthroscopic surface-holding repair and were monitored with the Japanese Orthopaedic Association, Constant-Murley, and University of California-Los Angeles scores to assess the clinical outcome. The mean follow-up period was 17.9months (range, 12-40months). Cuff repair integrity was evaluated by magnetic resonance imaging. All 3 rating systems at the time of final follow-up reflected a significant improvement in functional recovery of the shoulder compared with the preoperative scores. The overall rate of rotator cuff retear was 19.0% (22 of 116 shoulders), and the rates were 13.6% (9 of 66 shoulders) for small and medium-sized tears and 26% (13 of 50 shoulders) for large and massive tears. The rate for large and massive tears was much higher in patients older than 70years (58.3%) compared with those younger than 70years (36.3%), whereas the retear rates were similar in these 2 groups (22.2% and 17.5%, respectively). Arthroscopic surface-holding repair technique with medial suture and transosseous fixation improved rotator cuff healing. This method may be useful both for young patients and for elderly patients, who frequently have chronic large and massive tears, including osteoporotic bones.

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.

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.

Advanced Age Diminishes Tendon-to-Bone Healing in a Rat Model of Rotator Cuff Repair

Background: Advanced patient age is associated with recurrent tearing and failure of rotator cuff repairs clinically; however, basic science studies have not evaluated the influence of aging on tendon-to-bone healing after rotator cuff repair in an animal model. Hypothesis/Purpose: This study examined the effect of aging on tendon-to-bone healing in an established rat model of rotator cuff repair using the aged animal colony from the National Institute on Aging of the National Institutes of Health. The authors hypothesized that normal aging decreases biomechanical strength and histologic organization at the tendon-to-bone junction after acute repair. Study Design: Controlled laboratory study. Methods: In 56 F344xBN rats, 28 old and 28 young (24 and 8 months of age, respectively), the supraspinatus tendon was transected and repaired. At 2 or 8 weeks after surgery, shoulder specimens underwent biomechanical testing to compare load-to-failure and load-relaxation response between age groups. Histologic sections of the tendon-to-bone interface were assessed with hematoxylin and eosin staining, and collagen fiber organization was assessed by semiquantitative analysis of picrosirius red birefringence under polarized light. Results: Peak failure load was similar between young and old animals at 2 weeks after repair (31% vs 26% of age-matched uninjured controls, respectively; P > .05) but significantly higher in young animals compared with old animals 8 weeks after repair (86% vs 65% of age-matched uninjured controls, respectively; P < .01). Eight weeks after repair, fibroblasts appeared more organized and uniformly aligned in young animals on hematoxylin and eosin slides compared with old animals. Collagen birefringence analysis of the tendon-to-bone junction demonstrated that young animals had increased collagen fiber organization and similar histologic structure compared with age-matched controls (53.7 ± 2.4 gray scales; P > .05). In contrast, old animals had decreased collagen fiber organization and altered structure compared with age-matched controls (49.8 ± 3.1 gray scales; P < .01). Discussion: In a rat model of aging, old animals demonstrated diminished tendon-to-bone healing after rotator cuff injury and repair. Old animals had significantly decreased failure strength and collagen fiber organization at the tendon-to-bone junction compared with young animals. This study implies that animal age may need to be considered in future studies of rotator cuff repair in animal models. Clinical Relevance: With increasing age and activity level of the population, the incidence of rotator cuff tears is predicted to rise. Despite advances in rotator cuff repair technique, the retear rate remains specifically high in elderly patients. The findings of this research suggest that aging negatively influences tendon-to-bone healing after rotator cuff repair in a validated animal model.

Current Trends in Rotator Cuff Repair: Surgical Technique, Setting, and Cost

The purpose of this study was to evaluate national trends in the surgical setting and hospital costs of shoulder arthroscopy and rotator cuff repair (RCR) using the Florida State surgical database and national inpatient database. In part I we analyzed population-adjusted shifts in RCR technique (arthroscopic v open) in the Florida surgical database from 2000-2007 and quantified the procedural codes associated with arthroscopic and open RCR. In part II we analyzed the Nationwide Inpatient Sample database from 2001-2009 for the total number of inpatient RCRs, the inpatient hospital type (rural, urban non-teaching, or urban teaching), and the cost. Part I showed a 163% increase in outpatient procedures in Florida, with a 353% increase in arthroscopic RCRs. There was a concurrent decrease in open RCRs; however, the overall trend was a 2-fold increase in total RCRs. Associated procedures such as subacromial decompression, distal clavicle resection, and extensive glenohumeral debridement increased by 440%, 589%, and 1,253%, respectively. Part II showed an overall 58.8% decrease in inpatient RCRs that was similar across all hospital settings, with an increase in RCR-associated hospital charges by 144.9%, whereas hospital costs only increased by 85.2%. The study confirms a shift toward arthroscopic RCR and associated procedures in the outpatient setting. The increased financial cost partly explains the shift; nevertheless, future studies are needed to further examine national trends. This study examining RCR trends by hospital type, cost, and setting further elucidates how orthopaedic surgery practice is evolving with the implementation of arthroscopic RCR in the past decade.

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

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. We quantified the biomechanical properties of the repaired rabbit subscapularis tendon after (1) single-row, (2) double-row, and (3) transosseous-equivalent rotator cuff repair techniques and compared the ratios of repairs to previously published data for human repairs. 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%. 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/transosseous-equivalent 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). Subscapularis repairs in the rabbit at Time 0 result in comparable ratios to human supraspinatus repairs. 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.