Editorial Commentary: Dermal Allografts Are Indicated for Repair of Irreparable Rotator Cuff Tears and for Revision Surgery,and May Be Cost-Effective for Primary Repair

Improving rotator cuff repair results is the goal of all shoulder surgeons. The addition of a biologic graft may speed healing, allow accelerated rehabilitation, and increase healing rates. Recent research suggests that augmentation of rotator cuff repair using dermal allograft may be cost-effective. Indications for dermal allografts are revision rotator cuff repairs and primary cuff repairs in which a tensionless repair cannot be accomplished. Allografts act as a load-sharing device to allow tendons to heal without tension. They also serve to fill the gap in irreparable cuff tears. It is important to understand that augmentation will not compensate for advanced muscle fatty atrophy or neurapraxia. Precautions to prevent Cutibacterium acne nosocomial infection are essential. The healing time or dermal grafts is considerably longer than the repaired native cuff tendon, requiring supervised rehabilitation. Dermal allografts are a crucial tool for repair of irreparable rotator cuff tears and for revision surgery. From an economic standpoint, they now also may be considered for use in primary rotator cuff repair surgery.     

Modified load sharing rip-stop technique in patients with traumatic transtendinous rotator cuff tear: Surgical technique and clinical outcomes

BackgroundTranstendinous rotator cuff tear is likely to occur due to trauma in sports activities, with a frequency of <2% of total rotator cuff tears. These tears are difficult to treat because of limited tendon tissue in the proximal stump, and standard repair techniques are sometimes ineffective. Few studies have reported on the repair technique and clinical outcomes for transtendinous rotator cuff tear, and an appropriate repair technique has, therefore, not been established. The purpose of this study was to use our modified load sharing rip-stop technique to repair transtendinous rotator cuff tear and to clarify the clinical effectiveness of this technique.MethodsThis was a retrospective case series review of eight patients who underwent the modified load sharing rip-stop technique for repairing traumatic transtendinous rotator cuff tear between January 2013 and June 2017. The eight patients were followed up for at least 2 years (range: 24–41 months). Cuff integrity was evaluated using magnetic resonance imaging at 12 months after surgery using the Sugaya classification. We evaluated the pre- and postoperative ranges of motion, American Shoulder and Elbow Surgeons score, Constant Shoulder Score, and muscle strength at 90° abduction. Data were analyzed using the Mann–Whitney U test and Fisher's exact tests. P < .05 was considered to indicate statistical significance.ResultsSix patients were classified as Sugaya I and two as Sugaya II. ASES score (38.5–90.2, P = .0008), Constant shoulder score (36.5–79, P = .002), flexion (85°–158.1°, P = .002), abduction (85°–157.5°, P = .001), external rotation (38.8°–55°, P = .024), and muscle strength at 90° abduction (2.95–5.39 kg, P = .028) improved significantly. Six patients were able to return to their previous sports activity.ConclusionUsing our modified load sharing rip-stop technique for repair of transtendinous rotator cuff tear, patients obtained good clinical outcomes and could return to sports activities.     

Arthroscopic versus mini-open rotator cuff repair: a prospective,randomized study with 24-month follow-up

This prospective, randomized study was performed to evaluate the results of mini-open and arthroscopic rotator cuff repair in a comparative case series of patients followed for 24 months. A total of 125 patients were randomized to mini-open (Group I) or arthroscopic (Group II) rotator cuff repair at the time of surgical intervention. The University of California Los Angeles (UCLA) score, the American Shoulder and Elbow Surgeons (ASES) index, and muscle strength were measured to evaluate the clinical results, while magnetic resonance arthrography was used at 24-month follow-up to investigate the postoperative rotator cuff integrity. Fifty-three patients in Group I and 55 patients in Group II were available for evaluation at 24-month follow-up. At 24-month follow-up, the UCLA score, the ASES index, and muscle strength were statistically significantly increased in both groups postoperatively, while no significant difference was detected between the 2 groups. Intact rotator cuffs were investigated in 42 patients in Group I and 35 in Group II, and there was a significant difference in postoperative structural integrity between the two groups (P < 0.05). When analysis was limited to the patients with full-thickness tear, the muscle strength of the shoulder was significantly better in Group II, and the retearing rate was significantly higher in Group II. Based on the results obtained from this study, it can be indicated that arthroscopic and mini-open rotator cuff repair displayed substantially equal outcomes, except for higher retearing rate in the arthroscopic repair group. While for patients with full-thickness tear, arthroscopic rotator cuff repair displayed better shoulder strength and significantly higher retearing rate as compared to mini-open rotator cuff repair at 24-month follow-up.     

A new tear pattern of the rotator cuff and its treatment: Fosbury flop tears

Purpose:The purpose of this report is to describe a new full-thickness tear pattern of the posterosuperior rotator cuff with reversal healing. We describe the specific radiologic signs associated with this tear pattern and the arthroscopic rotator cuff repair technique.Results:Among 97 patients, five demonstrated a tear of the posterosuperior rotator cuff with reversal healing. Characteristic radiographic findings included a thicker tendon than normal, the presence of a stump and accumulation of liquid in the superior-medial part of the subacromial bursa, and adhesions between the supraspinatus tendon and the wall of the subacromial bursa.Conclusion:Avulsion of the posterosuperior rotator cuff with reversal healing on its bursal-side is a less common condition. This type of lesion and distinct radiographic signs that can be recognized to facilitate anatomic repair of the rotator cuff.

Level of evidence:

Level IV.     

Repair of rotator cuff tears in golfers

Purpose: Golfers continue to play through the years that rotator cuff disease becomes more common. We sought to establish the results of acromioplasty and rotator cuff repair in golfers, including their ability to return to the sport. Study Type: Case series. Methods: Of 30 golfers who underwent 32 rotator cuff repairs, 29 were interviewed, completed a detailed questionnaire, and returned for a physical examination. All of the patients were recreational or regional tournament golfers. Fifteen had open acromioplasty and rotator cuff repair and 16 had arthroscopic acromioplasty and mini-open repair. The average age at surgery was 60 years (range, 39 to 76 years). At surgery, most were moderate size tears (2 to 6 cm²). Results: At average follow-up of 37 months (range, 24 to 60 months), all but 3 patients are currently golfing. For patients who are currently golfing, there was no significant difference in handicaps or drive distances at most recent follow-up compared with presymptomatic handicaps and drive distances (P >.05). Twenty-three patients report that they are playing at their presymptomatic competitive level without pain. Three patients report playing at a lower competitive level than before. Conclusion: In our experience, acromioplasty and rotator cuff repair predictably allow for eventual return to pain-free golfing at a similar competitive level for most recreational-level athletes.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 2 (February), 2001: pp 165–172     

Is acromioplasty necessary in the setting of full-thickness rotator cuff tears? A systematic review

BackgroundThe benefits of acromioplasty in treating rotator cuff disease have been debated. We systematically reviewed the literature regarding whether acromioplasty with concomitant coracoacromial(CA) release is necessary for the successful treatment of full-thickness rotator cuff tears.ResultsFour studies fulfilled the inclusion criteria. They reported on 354 patients (mean age, 59 years; range 3–81 years) with a mean follow-up of 22 months (range 12–24 months). There were two level-I and two level-II studies. Two studies compared rotator cuff repair with versus without acromioplasty, and two studies compared rotator cuff repair with versus without subacromial decompression (acromioplasty, CA ligament resection, and bursectomy). The procedures were performed arthroscopically, and the CA ligament was released in all four studies. There were no statistically significant differences in clinical outcomes between patients treated with acromioplasty compared with those treated without acromioplasty.ConclusionsThis systematic review of the literature does not support the routine use of partial acromioplasty or CA ligament release in the surgical treatment of rotator cuff disease. In some instances, partial acromioplasty and release of the CA ligament can result in anterior escape and worsening symptoms. Further research is needed to determine the optimum method for the operative treatment of full-thickness rotator cuff tears.

Level of evidence

Level I, systematic review of level I and II studies.     

Outcome analysis of arthroscopic treatment of partial thickness rotator cuff tears

Background:

Partial thickness rotator cuff tears occupy an important position in the spectrum of rotator cuff disease. The development of a more comprehensive classification has been sought to address both the tear location and extent, which may influence clinical results. The purpose of this study is to classify partial thickness rotator cuff tears according to the arthroscopic findings and to evaluate the clinical outcomes after arthroscopic repair of partial thickness tears.

Materials and Methods:

One hundred and two patients had arthroscopic treatment of partial thickness rotator cuff tears. The inclusion criterion for the study was a partially torn supraspinatus tendon involving articular or bursal side, verified by direct arthroscopic visualization. Outcome analysis was exclusively applied to patients who underwent transtendon repair, using the shoulder index of American Shoulder and Elbow Society and the University of California Los Angeles (UCLA) rating system.

Results:

Partial thickness rotator cuff tears were divided into five groups according to arthroscopic findings. There was significant improvement after surgery in all parameters of clinical evaluation in the tears that warranted repair. Arthroscopic repair in situ (transtendon technique) may be the preferred option in unstable partial thickness tear.

Conclusion:

The proposed classification system may assist decision making in the treatment of partial thickness rotator cuff tears.     

Trends in the most cited articles in shoulder surgery, 1900–2019

BackgroundOur purpose was to identify the 100 most cited articles in the shoulder surgery literature published in past decade and to compare them with the 100 most cited “classic” shoulder surgery articles to identify trends in the topics of shoulder research.MethodsUsing the term “shoulder,” we searched the Clarivate Analytics’ Web of Science Core Collection database for 2 periods: 2010 through 2019 (“contemporary group,” n = 12,394) and 1900 through 2009 (“classic group,” n = 8790). We used the database sort function to order articles by number of citations. Titles, abstracts, and, when necessary, full text were screened to determine relevance to orthopedic shoulder topics until the 100 most cited articles were determined for each group. We analyzed the following article characteristics: title, author(s), publication year, journal, geographic origin, article type (clinical vs basic research), study design, and level of evidence (for clinical articles). P < .05 was considered significant.ResultsThe 3 journals with the most articles in the contemporary group were the American Journal of Sports Medicine (AJSM) (28%), the Journal of Shoulder and Elbow Surgery (JSES) (28%), and the Journal of Bone and Joint Surgery, American volume (JBJS Am) (23%). The top 3 journals in the classic group were JBJS Am (45%), AJSM (16%), and JSES (15%). The 3 most frequent topics in the contemporary group were rotator cuff tear (43%), instability (14%), and fractures (10%); those in the classic group were pathoanatomy (29%), rotator cuff (28%), and instability (17%). Compared with the classic group, the contemporary group had more articles on outcomes of common shoulder procedures, including rotator cuff repair (25% vs. 17%), arthroplasty (21% vs. 15%), arthroscopy (17% vs. 11%), reverse shoulder arthroplasty (13% vs. 7%), and the Latarjet procedure (7% vs. 2%). More articles reporting complications were found in the contemporary (9%) than in the classic (2%) group (P = .03). The contemporary group contained articles on topics not found in the classic group, such as platelet-rich plasma (8%), scaffolds (3%), infection (3%), Cutibacterium acnes (2%), stem cells (2%), superior capsular reconstruction (2%), bony increased offset reversed shoulder arthroplasty (2%), opioid issues (1%), and tendon transfer (1%).ConclusionThe most cited studies from 1900 to 2009 and 2010 to 2019 reported on the rotator cuff and shoulder instability. The most cited articles from 2010 to 2019 reflect the development of shoulder arthroscopy, shoulder arthroplasty, treatment of surgical complications, and augmentation or biologic interventions for rotator cuff repair.Level of evidenceLevel IV; Review Article     

Margin convergence: A method of reducing strain in massive rotator cuff tears

Increased security of fixation in rotator cuff repair is usually achieved by increasing the strength of fixation. Paradoxically, the problem can be approached by techniques that decrease the strain at the margins of the tear so that weaker fixation will still be adequate. Such techniques provide greater safety tolerances for the strength characteristics of suture, tendon, and bone. The principle of margin convergence can be applied to rotator cuff repair as a means to enhance the security of fixation by decreasing the mechanical strain at the margins of the tear. This strain reduction should also contribute to pain reduction by virtue of decreased stimulation of mechanoreceptors in the rotator cuff. The cliché no pain, no strain can be converted to a paradigm by reversal of its components to no strain, no pain.     

Rotator cuff repair during shoulder arthroplasty in rheumatoid arthritis

A prospective study of 40 shoulder arthroplasties in patients with rheumatoid arthritis was performed to evaluate the results of rotator cuff repair at the time of arthroplasty. A large cuff tear was present in 21 shoulders, and good repair of the cuff was performed in 9. In the other shoulders the repair was considered insufficient. All patients were clinically evaluated using the Hospital for Special Surgery 100-point scoring system. The minimum follow-up period for inclusion in this study was 2 years. The quality of the repair of the ruptured cuff at the time of surgery had a significant influence on the postoperative clinical score (linear regression model, P = .002). The clinical score of the shoulders with good repair of the rotator cuff improved considerably and continued to improve even after the first-year follow-up examination. Meticulous repair of the ruptured cuff at the time of arthroplasty is recommended.     

Editorial Commentary: Rotator Cuff Repair: Graft Augmentation Provides Promising Clinical Outcomes

Rotator cuff repair has benefitted from many technologic advances including the advent of arthroscopy, improved implant materials, and refined repair techniques. Despite our efforts to improve the science of rotator cuff repair, clinical advances have lagged far behind. Graft augmentation of rotator cuff repairs is an emerging and heterogeneous field that has significantly improved both healing rates and patient-reported metrics in initial data reporting. Treatment algorithms that guide the use of this novel surgical modality are of benefit to practicing orthopaedic surgeons.     

Current Perspectives on Rotator Cuff Anatomy

Understanding the anatomy of the rotator cuff and the surrounding structures that influence its function is essential to treating rotator cuff disease. During the past decade, advances in basic science and surgical technology have improved our knowledge of this anatomy. This review article presents the current concepts on rotator cuff anatomy and how they should be used in the surgical management of rotator cuff tears.     

Arthroscopic Rotator Cuff Repair in 2019: Linked,Double Row Repair for Achieving Higher Healing Rates and Optimal Clinical Outcomes

The primary aim of rotator cuff repair surgery is to restore the musculotendinous units by creating a complete, tension-free repair construct that optimizes conditions for tendon-to-bone healing. There are many factors outside the control of the surgeon that are capable of affecting the healing process; however, there are also a number of important technical considerations that the surgeon can control, including familiarity with methods to deal with immobile tissues and techniques to perform novel repair constructs. It is clear that linked double row repairs are more likely to heal, and healed rotator cuff repairs best restore shoulder strength, improve patients' satisfaction, and maximize functional outcomes.     

Arthroscopic repair of massive,contracted, immobile rotator cuff tears using single and double interval slides: technique and preliminary results

Purpose: The purpose of this study is to describe the technique and review the preliminary results of arthroscopic repair of massive, contracted, immobile rotator cuff tears using an interval slide technique. Type of Study: Case series. Methods: From January 1999 to December 2000, the senior author (S.S.B.) performed arthroscopic rotator cuff repair on 94 massive rotator cuff tears. Of these, 9 (9.6%) were massive, severely contracted rotator cuff tears and required repair using an interval slide technique. A single interval slide was used in 6 patients, and a double interval slide was used in 3 patients. All patients were evaluated preoperatively and postoperatively using a modified University of California Los Angeles (UCLA) scoring system. Results: At a mean follow-up time of 17.9 months (range, 10–24 months), 8 of 9 patients were satisfied with the procedure. The mean UCLA score increased from 10.0 preoperatively to 28.3 postoperatively (P < .00001). All patients showed some improvement in active motion, strength, or function. Active forward flexion improved significantly, from a preoperative mean of 108° to a postoperative mean of 146.1° (P = .025). Active external rotation increased significantly from a preoperative mean of 24.4° to a postoperative mean of 35.0° (P = .04). A significant increase in strength grade (2.2 to 3.6; P < .005) and function (2.5 to 7.1; P < .0005) were also seen. We encountered no significant complications to the procedure. Conclusions: The interval slide technique provides a method of mobilization of massive, severely contracted, immobile rotator cuff tears allowing repair of previously irreparable tears. This technique, in conjunction with arthroscopic rotator cuff repair, may provide patients with improvements in pain, motion, strength, and overall shoulder function. Level of Evidence: Level IV.     

关节镜下止点内移缝合修复巨大肩袖撕裂

目的：探讨关节镜下止点内移缝合修复巨大肩袖撕裂的方法和疗效。方法：回顾性分析2015年3月至2019年4月行关节镜下止点内移缝合修复巨大肩袖撕裂患者27例。其中男12例,女15例;年龄37~74（56.1±8.9）岁。术中根据肩袖张力,选用关节镜下双排缝线桥技术修复5例,单排修复22例,其中7例部分肩袖修复。手术前后采用美国加州大学洛杉矶分校（University of California Los Angeles,UCLA）评分,美国肩肘外科协会（American Shoulder and Elbow Surgeons Form,ASES）评分评估肩关节功能,视觉模拟评分（visual analogue scale,VAS）评估疼痛情况。结果：所有患者获随访,时间8~40（18.0±5.9）个月,UCLA评分由术前的（8.67±0.78）分提高至末次随访的（30.89±1.07）分（t=43.56,P<0.001）;ASES评分由术前的（8.56±0.67）分提高至末次随访的（12.63±0.33）分（t=15.28,P<0.001）;VAS评分由术前的6.00（5.00~7.00）分改善至末次随访的0.00（0.00~2.00）分（Z=-4.56,P<0.001）。3例患肩上举不能过顶,但无疼痛,不影响日常工作、生活,其中2例为部分肩袖修补。结论：关节镜下止点内移缝合修复巨大肩袖撕裂能取得较满意的疗效,大部分病例可选择单排完全或部分修复肩袖。     

An in-vitro study of rotator cuff tear and repair kinematics using single- and double-row suture anchor fixation

Purpose:

Double-row suture anchor fixation of the rotator cuff was developed to reduce repair failure rates. The purpose of this study was to determine the effects of simulated rotator cuff tears and subsequent repairs using single- and double-row suture anchor fixation on three-dimensional shoulder kinematics. It was hypothesized that both single- and double-row repairs would be effective in restoring active intact kinematics of the shoulder.

Materials and Methods:

Sixteen fresh-frozen cadaveric shoulder specimens (eight matched pairs) were tested using a custom loading apparatus designed to simulate unconstrained motion of the shoulder. In each specimen, the rotator cuff was sectioned to create a medium-sized (2 cm) tear. Within each pair, one specimen was randomized to a single-row suture anchor repair, while the contralateral side underwent a double-row suture anchor repair. Joint kinematics were recorded for intact, torn, and repaired scenarios using an electromagnetic tracking device.

Results:

Active kinematics confirmed that a medium-sized rotator cuff tear affected glenohumeral kinematics when compared to the intact state. Single- and double-row suture anchor repairs restored the kinematics of the intact specimen.

Conclusions:

This study illustrates the effects of medium-sized rotator cuff tears and their repairs on active glenohumeral kinematics. No significant difference (P ≥ 0.10) was found between the kinematics of single- and double-row techniques in medium-sized rotator cuff repairs.

Clinical Relevance:

Determining the relative effects of single- and double-row suture anchor repairs of the rotator cuff will allow physicians to be better equipped to treat patients with rotator cuff disease.     

Functional evaluation of patient after arthroscopic repair of rotator cuff tear

BackgroundRotator cuff tear is a common problem either after trauma or after degenerative tear in old age group. Arthroscopic repair is the current concept of rotator cuff repair. Here, we are trying to evaluate the functional outcome after arthroscopic repair of full thickness rotator cuff tear (single row) in Indian population.Materials and methodsTwenty five patients (14 males and 11 females) who underwent arthroscopic repair of full thickness rotator cuff tear at a single institution were included in the study. Postoperatively patient's shoulder was rated according to UCLA score, pain was graded according to the visual analog score. The range of motion was analysed and documented.ResultsThe mean age of the patients were 50.48 years. The preoperative VAS score mode was 7 and post operative VAS was 1 (p value <0.001). The UCLA grading was good in 80% (n = 20), fair in 12% (n = 3), excellent in 8% (n = 2) and poor results were seen in none of the patients.The mean UCLA improved from a score of 15.84 to 30.28 with a p value <0.001. Mean postoperative forward flexion was 161.6°, mean abduction was 147.6° and mean external rotation was 45.4°.ConclusionArthroscopic repair is a good procedure for full thickness rotator cuff tear with minimal complications. The newer double row repair claims to be biomechanically superior with faster healing rates without functional advantages, hence we used a single row repair considering the Indian population and the cost effectiveness of the surgery with good to excellent results.     

Comparing bone resorption after anatomical shoulder arthroplasty between various surgical procedures using a single-stem model

BackgroundIn shoulder arthroplasty, bone resorption around the stem can lead to stem loosening and makes surgery difficult at the time of revision. Proximal bone resorption after reverse shoulder arthroplasty can cause instability because of a decrease of deltoid wrapping effect. As factors of the stem itself, such as stem coating, shape, length, and use of bone cement, may also affect bone resorption, a single-stem model should be used to compare bone resorptions between different pathologies and surgical procedures. However, to date, a few reports have compared these differences in detail using a single-stem model. Therefore, we investigated the prevalence and location of humeral bone resorption in a single-stem model.MethodsThe study included 100 shoulders that underwent anatomical total shoulder arthroplasty (TSA) or humeral head replacement (HHR) with a single uncemented humeral stem from 2008 to 2018. The patients were 31 men and 69 women. The mean age at surgery was 72.9 years (range, 41-86 years). The patients were divided into three groups: especially, 25, 61, and 14 shoulders received TSA for primary osteoarthritis without rotator cuff tears (TSA group), HHR using an anatomical head with rotator cuff repair for cuff tear arthropathy (CTA) (HHR group), and HHR using a CTA head without rotator cuff repair (CTA group), respectively. Patients were monitored for a mean of 56 months (range, 12-98 months). The location of bone resorption was divided into seven zones as follows: zone 1, greater tuberosity; zone 2, lateral diaphysis; zone 3, lateral diaphysis beyond the deltoid tuberosity; zone 4, tip of the stem; zone 5, medial diaphysis beyond the deltoid tuberosity; zone 6, medial diaphysis; and zone 7, calcar region. The degree of bone resorption was classified from grade 0 to 4.ResultsBone resorption of grade 3 or higher was significantly more frequent at the greater tuberosity in the HHR and CTA groups (P < .001 and P < .001, respectively) than that in the TSA group. Grade 4 bone resorption was significantly more frequent in the CTA than that in the TSA and HHR groups in zone 1 (P = .016 and P = .041, respectively).ConclusionThe state of attachment of the rotator cuff to the greater tuberosity might affect bone resorption at the greater tuberosity, such as the greater tuberosity after shoulder arthroplasty. In cases of shoulder arthroplasty for arthropathy with rotator cuff tear, performing rotator cuff repair might prevent bone resorption.Level of evidenceLevel IV; Prognosis Study     

全关节镜下肩袖修补术对老年肩袖损伤患者术后72 h内疼痛程度和并发症的影响

目的:分析全关节镜下肩袖修补术与小切口肩袖修补术对老年肩袖损伤患者的临床效果。方法:选取2017年1月至2018年11月收治的60例老年肩袖损伤患者作为研究对象,男37例,女23例;年龄61~77(63.45±12.34)岁;病程6~12(5.32±1.02)个月;左侧29例,右侧31例。其中,行全关节镜下肩袖修补术者30例,为观察组;行小切口肩袖修补术者30例,为对照组。观察并记录两组患者术前术后美国加州大学肩关节评分系统(University of California,Los Angeles,UCLA)评分,美国肩肘外科协会(American Shoulder and Elbow Surgeons,ASES)评分,Constant-Murley评分,肩关节前屈活动度、外旋活动度、外展活动度,术后72 h内视觉模拟疼痛评分(visual analogue scale,VAS)及并发症发生情况,然后进行对比分析。结果:两组患者术后UCLA评分、ASES评分、Constant-Murley评分较术前均显著提高(P<0.05),两组术后UCLA、ASES、Constant-Murley评分相比差异无统计学意义(P>0.05)。两组患者术后肩关节前屈活动度、外旋活动度、外展活动度较术前均显著增加(P<0.05),术后两组间比较差异无统计学意义(P>0.05);观察组术后24、48、72 h VAS低于对照组(P<0.05);观察组并发症总发生率13.33%(4/30)低于对照组33.33%(10/30)(P<0.05)。结论:全关节镜下肩袖修补术和小切口肩袖修补术均可以改善老年肩袖损伤后的肩部功能,但全关节镜下肩袖修补术后72 h内疼痛程度和并发症均明显优于小切口肩袖修补术,可根据患者临床实际情况与需求进行选择。     

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

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) transosseous-equivalent 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/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).

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.