Cyclic loading of anchor-based rotator cuff repairs: Confirmation of the tension overload phenomenon and comparison of suture anchor fixation with transosseous fixation

Previous experimental studies of failure of rotator cuff repair have involved single pull to ultimate load. Such an experimental design does not represent the cyclic loading conditions experienced in vivo. We created 1 ×2 cm rotator cuff defects in 16 cadaver shoulders, repaired each defect with three MitekRC suture anchors (Mitek Surgical Products, Inc, Westwood, MA) using simple sutures of No. 2 Ethibond, and cyclically loaded the repairs by a servohydraulic materials test system actuator at physiological rates and loads (rate of 33 mm/s, load 180 N). A progressive gap was noted in each specimen, for a 100% rate of failure of the repairs. The central suture always failed first and by the largest magnitude, confirming tension overload centrally. One specimen exhibited combined bone and tendon failure, but the other 15 specimens failed through the tendon. Overall, the repairs failed to 5 mm and 10 mm at an average of 61 cycles and 285 cycles, respectively. Half the specimens were less than 45 years of age and had a 5-mm and 10-mm failure at an average of 107 and 478 cycles, respectively. The other half were over 45 years of age and failed to 5 mm and 10 mm at an average of 17 and 91 cycles, respectively, indicating more rapid failure of the rotator cuff tendons in the older group, and this was statistically significant (P ≤ .02). Comparison of suture anchor fixation in this study with transosseous bone tunnel fixation in a previous cyclic loading study at this institution indicates that bone fixation by suture anchors is significantly less prone to failure than bone fixation through bone tunnels (P = .0008). Changing the bone fixation from bone tunnels to suture anchors effectively transferred the weak link from bone to tendon.     

Suture anchor fixation strength in osteopenic versus non-osteopenic bone for rotator cuff repair

Introduction

Rotator cuff tears are increasing with age. Does osteopenic bone have an influence on the pullout strength of suture anchors?

Materials and methods

SPIRALOK 5.0 mm (DePuy Mitek), Super Revo 5 mm and UltraSorb (both ConMed Linvatec) suture anchors were tested in six osteopenic and six healthy human cadaveric humeri. Incremental cyclic loading was performed. The ultimate failure load, anchor displacement, and the mode of failure were recorded.

Results

In the non-osteopenic bone group, the absorbable SPIRALOK 5.0 mm achieved a significantly better pullout strength (274 N ± 29 N, mean ± SD) than the titanium anchor Super Revo 5 mm (188 N ± 34 N, mean ± SD), and the tilting anchor UltraSorb (192 N ± 34 N, mean ± SD). In the osteopenic bone group no significant difference in the pullout strength was found. The failure mechanisms, such as anchor pullout, rupture at eyelet, suture breakage and breakage of eyelet, varied between the anchors.

Conclusion

The present study demonstrates that, in osteopenic bone, absorbable suture anchors do not have lower pullout strengths than metal anchors. In normal bone, the bioabsorbable anchor in this study even outperformed the non-absorbable anchor.

     

关节镜下修复类风湿关节炎病人肩袖损伤的疗效分析

目的 探讨关节镜下修复类风湿关节炎病人肩袖损伤的疗效。方法 回顾性分析2015年3月至2018年7月的17例（20肩）类风湿关节炎病人的病例资料,均行关节镜下肩袖修复术,其中肩袖部分撕裂6例（7肩）,完全撕裂11例（13肩）。收集并比较病人术前及术后1年的疼痛视觉模拟量表（visual analogue scale, VAS）评分。分析病人术前、术后6个月及1年的Constant-Murley肩关节功能评分和美国加利福尼亚大学洛杉矶分校（University of California at Los Angeles, UCLA）肩关节评分。分析病人术前、术后1年的外展、外旋、内旋等肩关节活动度。结果 17例病人术后均随访1年以上。本组术后6个月和1年的UCLA评分分别为（27.15±2.85）分、（30.55±2.11）分,Constant-Murley评分分别为（73.20±4.07）分、（83.35±3.84）分,与术前相比逐步提升,各个时间点的评分比较,差异均有统计学意义（P均＜0.05）。静息和活动状态下的VAS评分由术前的（5.95±2.37）分、（7.35±2.13）分改善至术后的（2.20±1.23）分和（2.40±1.43）分,术前肩关节外展、外旋及内旋活动度由术前的77.30°±18.20°、37.25°±10.03°、35.25°±12.74°改善至术后的131.80°±20.22°、47.85°±7.66°和59.40°±12.12°,差异均有统计学意义（P均＜0.05）。无论是肩袖完全撕裂还是部分撕裂的类风湿关节炎病人,通过关节镜下肩袖修复术后,病人动、静态疼痛及内旋活动度恢复良好;但在肩袖完全撕裂的病人中,术后外展活动度及病人满意度均未见明显改善（P均＞0.05）。结论 关节镜下修复类风湿关节炎病人肩袖损伤能较好地缓解病人疼痛,对于肩袖部分撕裂的病人也能较好地改善肩关节的活动度和术后满意度。     

Trends in rotator cuff surgery: Research through the decades

IntroductionThe aim of this study is to analyse the most cited articles in rotator cuff surgery and identify trends in topics by decade to see which areas may still need further investigationMethodsJournal Citation Index was searched to find articles using the search terms pertaining to “rotator cuff repair”. All articles were ranked according to most cited, and then further analysed to find most cited articles in each decade. Articles were grouped into topics to find themes for each decade.ResultsAll the most cited articles were published in 6 orthopaedic journals. Only 4 of the top 30 citations provided level I evidence. Each decade’s most cited articles seemed to fit into a broad topic, with platelet-rich plasma and biologic augmentation being prominent in the last decade.ConclusionThere are still many unanswered questions in rotator cuff surgery, but this may be because success of certain treatment options are highly dependent on patient selection. Despite growing numbers of articles being published on rotator cuff repairs, the level of evidence remains low. Larger, collaborative projects may help in answering the common dilemmas that still face shoulder surgeons.     

Arthroscopic versus mini-open rotator cuff repair: A meta-analysis

BackgroundAn all-arthroscopic rotator cuff repair (ASR) may result in less postoperative pain and better functional outcomes than the mini-open (MOR) approach. This meta-analysis provides an updated assessment of the current literature which compares the clinical outcomes of mini-open versus all arthroscopic rotator cuff repair techniques.Material and methodsThe main online databases were accessed in October 2021. All the trials directly comparing primary ASR versus MOR for rotator cuff rupture were accessed. Studies concerning revision settings were not eligible, nor where those combining the surgical procedures with other adjuvants.ResultsA total of 21 articles were retrieved. Data from 1644 procedures (ASR = 995, MOR = 649) were collected. The mean follow-up was 26.7 (6.0–56.4) months. Comparability was found between ASR and MOR groups at baseline with regards to age (P = 0.3), gender (P = 0.7) and mean duration of the follow-up (P = 0.7). No difference was found between ASR and MOR with regard to surgical duration (P = 0.05), Constant score (P = 0.2), University of California at Los Angeles Shoulder (P = 0.3), American Shoulder and Elbow Surgeons Shoulder (P = 0.5), VAS (P = 0.2), forward flexion (P = 0.3), abduction (P = 0.3), external rotation (P = 0.2), internal rotation (P = 0.7), re-tear (P = 0.9), adhesive capsulitis (P = 0.5).ConclusionArthroscopic and mini-open rotator cuff repair result in similar clinical outcomes. Male gender and older age lead to greater rates of rotator cuff re-tears, while longer surgical duration was associated with a greater rate of adhesive capsulitis.     

Re-tears after rotator cuff repair: Current concepts review

Re-tear following rotator cuff repair is common and has been reported to range from between 13 and 94% despite satisfactory clinical outcomes following rotator cuff surgery. Various risk factors have been associated with an increased tear rate, including patient factors, tear and shoulder morphology, repair technique, and rehabilitation regimes. Different modes of rotator cuff failure have been described. The management of re-tear in patients following rotator cuff repair is challenging and depends on the age, functional status and requirements of the patient, and re-tear size and residual tendon length. This article aims to review the factors associated with rotator cuff re-tear. It describes which of these are associated with poor clinical outcomes, and discusses the long-term outcomes of re-tear and treatment options.     

Biomechanical comparison of suture anchor versus margin convergence plus suture anchor for rotator cuff repair

Objective: To evaluate results of margin convergence versus suture anchors in rotator cuff repair, and to determine which method is mechanically superior. Methods: Eighteen kangaroo shoulders were randomly divided into three groups (n = 6). A full thickness tendon defect 1.0 cm × 1.5 cm in size was created in the supraspinatus tendon at humeral insertion, simulating a massive rotator cuff tear. Three different techniques were employed for rotator cuff repair: (i) Mitek GII suture anchor alone (Group 1); (ii) margin convergence alone (Group 2); and (iii) margin convergence plus Mitek GII suture anchor (Group 3). Combined loads were applied to each specimen. After completion of cyclic loading, the construct was loaded to failure. ANOVA and LSD (Least Significant Difference) multiple comparisons of the means were applied to results. Results: Cyclic load testing showed progressive gap formation in each repaired specimen with increasing cycles. Group 1 reached 50% failure at an average of 34 cycles, Group 2 at 75 cycles and Group 3 at 73 cycles. There were significant difference between Groups 1 and 2, and Groups 1 and 3 (P ≤ 0.001). After 100 loading cycles, the average gap size was 6.8 mm, 6.1 mm and 4.7 mm in Groups 1, 2 and 3, respectively. There was a significant difference between Groups 1 and 3 (P ≤ 0.015). All specimens eventually reached failure. Conclusion: Rotator cuff repairs with margin convergence +/? suture anchor were far stronger than suture anchor alone, both in gap formation and ultimate failure load. However, progressive gap formation with cyclic loading seems inevitable after cuff repair, which may facilitate clinical understanding of the phenomena of re‐tear or residual defect.     

Cyclic loading of rotator cuff repairs: A comparison of bioabsorbable tacks with metal suture anchors and transosseous sutures

Purpose: The purposes of the study were (1) to compare rotator cuff repair strengths after cyclic loading of 2 bioabsorbable nonsuture-based tack-type anchors, transosseous sutures, and a metal suture-based anchor, and (2) to correlate bone mineral density with mode of failure and cycles to failure. We hypothesized that specimens with a lower bone density would fail through bone at a lower number of cycles independent of the method of cuff fixation. Type of Study: Ex vivo biomechanical study. Methods: Standardized full-thickness rotator cuff defects were created in 30 fresh-frozen cadaveric shoulders that were randomized to 1 of 4 repair groups: transosseous sutures; Mitek Super suture anchors (Mitek Surgical Products, Westwood, MA); smooth bioabsorbable 8-mm Suretacs (Acufex, Smith & Nephew Endoscopy, Mansfield, MA); or spiked bioabsorbable 8-mm Suretacs (Acufex). All repairs were cyclically loaded from 10 to 180 N; the numbers of cycles to 50% (gap, 5 mm) and 100% (gap, 10 mm) failure were recorded. Results: In comparing the repair groups, we found only 1 significant difference: the number of cycles to 100% failure was significantly higher (P <.05) for the smooth bioabsorbable tack than for the transosseous suture group. There were no statistically significant (P ≤.05) differences in bone mineral densities with regard to each specimen’s mode of failure. Conclusions: Our results suggested that immediate postoperative fixation provided by bioabsorbable tacks was similar to that provided by Mitek anchors and more stable than that provided by transosseous sutures. Therefore, the immediate postoperative biomechanical strength of bioabsorbable tacks seems comparatively adequate for fixation of selected small rotator cuff tears. However, additional evaluation in an animal model to examine degradation characteristics and sustained strength of repair is recommended before clinical use.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 4 (April), 2001: pp 360–364     

Use of biologics in rotator cuff disorders: Current concept review

Poor tendon to bone healing following rotator cuff repair has led to the continued interest and investigation into biological augmentation. The biology of tendinopathy is not fully understood and consequently the availability of disease modifying therapeutic targets is limited. A ceiling of benefit has been reached by mechanical optimisation of rotator cuff repair and thus, in order to improve healing rates, a biological solution is required. This review focuses on the strategies to biologically augment rotator cuff disorders with an emphasis on rotator cuff repair. Leucocyte rich platelet rich plasma has been shown to improve healing rates without clinically relevant improvements in outcome scores. Similarly, improved healing rates have also been reported with bone marrow stimulation and in long-term follow-up with bone marrow concentrate. Extracellular matrix (ECM) and synthetic scaffolds can increase healing through mechanical and or biological augmentation. A potential third category of scaffold is bio-inductive and has no mechanical support. Studies involving various scaffolds have shown promising results for augmentation of large to massive tears and is likely to be most beneficial when tendon quality is poor, however level I evidence is limited.