Effect of single- and double-row rotator cuff repair at the tendon-to-bone interface: preliminary results using an in vivo sheep model

Establishing a rabbit model with massive supraspinatus tendon defect for investigating scaffold-assisted tendon repair

BACKGROUND

Shoulder pain and disability from rotator cuff tears remain challenging clinical problem despite advancements in surgical techniques and materials. To advance our understanding of injury progression and develop effective therapeutics using tissue engineering and regenerative medicine approaches, it is crucial to develop and utilize animal models that closely resemble the anatomy and display the pathophysiology of the human rotator cuff. Among various animal models, the rabbit shoulder defect model is particularly favored due to its similarity to human rotator cuff pathology. However, a standardized protocol for creating a massive rotator cuff defect in the rabbits is not well defined. Therefore, the objective of our study was to establish a robust and reproducible model of a rotator cuff defect to evaluate the regenerative efficacy of scaffolds.

RESULTS

In our study, we successfully developed a rabbit model with a massive supraspinatus tendon defect that closely resembles the common rotator cuff injuries observed in humans. This defect involved a complete transection of the tendon, spanning 10 mm in length and encompassing its full thickness and width. To ensure stable scaffolding, we employed an innovative bridging suture technique that utilized a modified Mason-Allen suture as a structural support. Moreover, to assess the therapeutic effectiveness of the model, we utilized different scaffolds, including a bovine tendon extracellular matrix (ECM) scaffold and a commercial acellular dermal matrix (ADM) scaffold. Throughout the observation period, no scaffold damage was observed. Notably, comprehensive histological analysis demonstrated that the regenerative tissue in the tendon ECM scaffold group exhibited an organized and aligned fiber structure, indicating tendon-like tissue regeneration while the tissue in the ADM group showed comparatively less organization.

CONCLUSIONS

This study presents a comprehensive description of the implemented procedures for the development of a highly reproducible animal model that induces massive segmental defects in rotator cuff tendons. This protocol can be universally implemented with alternative scaffolds to investigate extensive tendon defects and evaluate the efficacy of regenerative treatments. The application of our animal model offers a standardized and reproducible platform, enabling researchers to systematically evaluate, compare, and optimize scaffold designs. This approach holds significant importance in advancing the development of tissue engineering strategies for effectively repairing extensive tendon defects.

Quantitative Magnetic Resonance Imaging-Based Tendon Healing of Different Regions of the Shoulder: Comparison Between the Suture-Bridge and Single-Row Techniques

Background

Rotator cuff retears occur more often at the proximal region with the suture-bridge (SB) technique than at the typical footprint region with the single-row (SR) technique. Few longitudinal clinical trials have focused on the postoperative tendon quality of the repaired rotator cuff at different regions between the 2 techniques.

Purpose

To compare tendon healing of the proximal and distal regions between the SB and SR techniques.

Study Design

Cohort study; Level of evidence, 3.

Methods

Included were consecutive patients who underwent arthroscopic rotator cuff repair and undertook clinical and magnetic resonance imaging (MRI) examinations at 3, 6, and 12 months postoperatively between 2016 and 2017. These patients were divided into the SB and SR groups according to the technique used. The repaired tendon was segmented into distal and proximal regions on ultrashort echo time-T2* mapping images. Clinical outcomes (Constant score, American Shoulder and Elbow Surgeons score, Fudan University Shoulder Score, and visual analog scale for pain) and MRI-based tendon healing (T2* values) of different regions were compared between the 2 groups. The differences in T2* values and clinical scores were determined by 1-way analysis of variance for repeated measurements.

Results

A total of 31 patients (17 in SB group and 14 in SR group) were included. At 12-month follow-up, significant improvements from preoperatively were achieved for all patients in all clinical scores (P < .001 for all). No significant between-group differences were found in T2* values of the distal region at any time point; however, the mean T2* value of the proximal region at 3 months was significantly higher in the SB group compared with the SR group (P = .03). This difference became nonsignificant at subsequent follow-up time points.

Conclusion

Significant clinical improvements over time can be expected in the first year after arthroscopic rotator cuff repair. In the early postoperative period, higher T2* values in the proximal region of the repaired tendon (representing inferior tendon quality) were seen with the SB technique compared with the SR technique; however, this phenomenon was resolved over time.

Animal Models of Rotator Cuff Injury and Repair: A Systematic Review

There are a large number of animal studies on rotator cuff injury and repair, but a lack of detailed research and evaluation on the animal models. This systematic review aims to provide a framework for animal studies and repair patches for rotator cuff injury. Four hundred nine animal studies were included, of which the most common animal model of rotator cuff injury is rat (53.56%), the most common site of rotator cuff injury is the supraspinatus tendon (62.10%), and the most common injury type (degree) is acute tear (full thickness) (48.41%). The most common research purpose is to evaluate the repair effect of the patch (24.94%), followed by the observation of pathophysiological changes after rotator cuff injury (20.87%). Among the five types of repair patch materials including nondegradable and degradable synthetic materials, autologous and allogeneic tissues, and naturally derived biomaterial, the last one is the mostly used (52.74%). For different animal models, the rodent models (rat and mouse) are the most commonly used and probably the most suitable species for preliminary studies of rotator cuff injury; the rabbit, canine, sheep, and goat models are more suitable for biomechanical performance testing, rehabilitation training, and validation of surgical methods; and the nonhuman primate models (monkey and baboon) are the closest to human, but it is more difficult to carry out the animal studies on them because of ethical issues, high feeding cost, and management difficulties.

Double-row rotator cuff repairs lead to more intensive pain during the early postoperative period but have a lower risk of residual pain than single-row repairs

PURPOSE

The purpose of this study is to compare pain patterns and identify factors associated with residual shoulder pain after rotator cuff repairs using double-row and single-row techniques.

METHODS

A cohort study was performed using patients who underwent arthroscopic rotator cuff repairs at our center in 2015. Patients were allocated according to the repair technique into an single-row (SR) group or a double-row (DR) group. Visual Analog Scale (VAS) scores for pain were assessed at 1 week, 3 months, 6 months, 12 months and 24 months after surgery. Functional and radiographic assessments were performed at least 24 months postoperatively. The proportion of patients with residual pain and factors associated with residual shoulder pain (VAS > 0 at the final follow-up) were analyzed in both groups.

RESULTS

Fifty-two patients were enrolled in the SR group, and 53 were enrolled in the DR group. The DR group appeared to have higher levels of pain 1 week (P < 0.001) and 3 months (P = 0.041) postoperatively, while at other time points, the pain intensity of the two groups was comparable. Fourteen (26.4%) and 25 (48.1%) patients in the DR and the SR groups, respectively, developed residual shoulder pain, (P = 0.022; RR 1.82). The univariate analysis and multiple regression revealed that a poorer quality of tendon tissue is related to residual pain in the SR group, whereas tendon retraction is associated with residual pain in the DR group. The rate of re-tear was similar between the two groups and between patients with and without residual pain.

CONCLUSIONS

The DR repair technique results in a greater intensity of pain than that of SR repair during the first 3 months after surgery; however, patients who underwent DR repair presented a significantly lower proportion of residual shoulder pain and better tendon quality after 2 years. Poorer tendon quality and larger tendon retraction as determined intraoperatively were risk factors for residual pain. These results highlight the necessity of promoting healing on the grounds of residual pain prevention.

LEVEL OF EVIDENCE

II.

Arthroscopic Rotator Cuff Repair With a Knotless Suture Bridge Technique: Functional and Radiological Outcomes After a Minimum Follow-Up of 5 Years

PURPOSE

To evaluate clinical and radiological outcomes of knotless suture bridge repair after a minimum of 5 years of follow-up.

METHODS

A prospective consecutive series of full-thickness supraspinatus atraumatic chronic tears was evaluated in the study. Tears were medium or large. Further inclusion criteria were minimum clinical follow-up of 5 years with magnetic resonance imaging (MRI) at 24 months and fatty infiltration <2. Patients with shoulder stiffness, arthritis, or rotator cuff tear involving the subscapularis tendon were excluded. An arthroscopic cuff repair was performed using a knotless double-row suture bridge technique with braided suture tapes. Clinical outcomes were evaluated using the Constant score, the American Shoulder and Elbow Surgeons score, strength score, and a visual analog scale. Tendon healing was analyzed according to Sugaya MRI classification at 24 months. A Sugaya score of 1 or 2 was considered as tendon healing. Statistical analysis was performed with the Student's t-test. P = .05 were considered statistically significant.

RESULTS

Sixty-eight patients were included in this series. Mean follow-up was equal to 68.8 ± 7 months. At last follow-up, the mean visual analog scale, American Shoulder and Elbow Surgeons score, and Constant scores improved significantly from 5.5 ± 1.6, 48.2 ± 13.1, 37.8 ± 8.3, to 2.1 ± 2.1 (P = 5.43 E-14), 87.4 ± 15.8 (P = 7.15 E-27), and 82.8 ± 14.7 (P = 1.01 E-33), respectively. Anteflexion improved from 99.3° ± 13.4° preoperatively to 136.6° ± 15.9° at last follow-up (P = 3.08 E-21). Strength score was significantly higher postoperatively (18.4 ± 6.7 vs 8.3 ± 3.5). MRI showed 88% (n = 57) of Sugaya 1-2 repairs. Patients with unhealed rotator cuffs showed significantly lower functional results than the Sugaya 1-2 group. No correlation between degree of retraction and rate of healing was observed. Four symptomatic patients (6%) required revision for failed rotator cuff repair.

CONCLUSIONS

Despite potential confounding factors, arthroscopic knotless suture bridge repair of rotator cuff tears with acromioplasty demonstrated excellent long-term results of tendon healing, pain relief, and improvement of shoulder function.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Biomechanical Comparison of a New Loop Suture Technique With Conventional Techniques of Flexor Tendon Repair: An In Vitro Study

INTRODUCTION

Flexor tendon repair techniques that can resist active forces are widely accepted. Despite that many suture techniques have been described, the "perfect repair" for flexor tendons cannot be achieved yet. We aimed to compare a new loop suture technique with commonly used flexor tendon repair methods biomechanically in hen tendon.

METHOD

We used 25 hen flexor tendons for each group (4-strand modified Kessler, grasping cruciate, Tsuge, and new technique groups). After the tendons were divided into 2, they were repaired according to these 4 techniques, were subjected to the initial stretching of 0.5 N, and pulled in the opposite directions. When a gap of 2 mm occurred, the test was terminated and the forces at that time were recorded. These strain forces were compared and evaluated statistically.

RESULTS

New technique had the best tensile strength results statistically. Modified Kessler and grasping cruciate took the second place and Tsuge repair gave the worst strain forces results.

CONCLUSIONS

With loop suture, 4 strands can be obtained with only 2 passes of the needle, and we think that much more tensile strength can be achieved because of the vertical transition and locking configurations of the new loop suture technique.

Biomechanic and histologic analysis of fibroblastic effects of tendon-to-bone healing by transforming growth factor β1 (TGF-β1) in rotator cuff tears

PURPOSE

To evaluate the effect of transforming growth factor β1 (TGF-β1) on tendon-to-bone reconstruction of rotator cuff tears.

METHODS

Seventy-two rat supraspinatus tendons were transected and reconstructed in situ. At 8 and 16 weeks, specimens of three groups; that is control, L-dose (low dose), and H-dose (high dose) were harvested and underwent a biomechanical test to evaluate the maximum load and stiffness values. Histology sections of the tendon-to-bone interface were identified by hematoxylin-eosin or Masson trichrome stain. Collagen type III was observed by picric acid sirius red staining under polarized light. The level of insulin-like growth factor 1 (IGF-1) and vascular endothelial growth factor (VEGF) was measured by the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

Collagen type III of the H-dose group had a significant difference in histology structure compared with the L-dose group (P<0.05). The maximum load and stiffness decreased significantly in the control group compared with the values of the L-dose and H-dose groups. The stiffness among the three groups differed significantly at the same postoperative time (P<0.05). Interestingly, progressive reestablishment of collagen type III affected tendon-to-bone healing significantly in the later stages.

CONCLUSION

The H-dose was associated with an increased collagen type III morphology stimulated by TGF-β1.

The Impact of Re-tear on the Clinical Outcome after Rotator Cuff Repair Using Open or Arthroscopic Techniques - A Systematic Review

Background:

It is generally accepted that rotator cuff repair gives satisfactory results in the long term, although most studies have so far shown a fairly high rate of structural failure or re-tear. The purpose of this review study is to assess whether failure of the repaired cuff to heal could negatively affect the functional outcome.

Methods:

This article includes an extensive Internet PubMed based research in the current English-language literature including level I to level V studies as well as systematic reviews.

Results:

According to this extended study research, the results are mixed; certain reports show that patients with a healed rotator cuff repair have improved function and strength compared to those with structural failure, whereas other studies support the generally perceived concept that tendon re-tear does not lead to inferior clinical outcome.

Conclusion:

Further high-level prospective studies with larger numbers of patients and longer follow up are needed to overcome the current debate over function between healed and failed rotator cuff repairs.

Biomechanical Performance of Medial Row Suture Placement Relative to the Musculotendinous Junction in Transosseous Equivalent Suture Bridge Double-Row Rotator Cuff Repair

PURPOSE

To compare the biomechanical performance of medial row suture placement relative to the musculotendinous junction (MTJ) in a cadaveric transosseous equivalent suture bridge (TOE-SB) double-row (DR) rotator cuff repair (RCR) model.

METHODS

A TOE-SB DR technique was used to reattach experimentally created supraspinatus tendon tears in 9 pairs of human cadaveric shoulders. The medial row sutures were passed either near the MTJ (MTJ group) or 10 mm lateral to the MTJ (rotator cuff tendon [RCT] group). After the supraspinatus repair, the specimens underwent cyclic loading and load to failure tests. The localized displacement of the markers affixed to the tendon surface was measured with an optical tracking system.

RESULTS

The MTJ group showed a significantly higher (P = .03) medial row failure (5/9; 3 during cyclic testing and 2 during load to failure testing) compared with the RCT group (0/9). The mean number of cycles completed during cyclic testing was lower in the MTJ group (77) compared with the RCT group (100; P = .07) because 3 specimens failed in the MTJ group during cyclic loading. There were no significant differences between the 2 study groups with respect to biomechanical properties during the load to failure testing.

CONCLUSIONS

In a cadaveric TOE-SB DR RCR model, medial row sutures through the MTJ results in a significantly higher rate of medial row failure.

CLINICAL RELEVANCE

In rotator cuff tears with tendon tissue loss, passage of medial row sutures through the MTJ should be avoided in a TOE-SB RCR technique because of the risk of medial row failure.

[Rotator cuff repair: single- vs double-row. Clinical and biomechanical results]

BACKGROUND

The goal of rotator cuff repair is a high initial mechanical stability as a requirement for adequate biological recovery of the tendon-to-bone complex. Notwithstanding the significant increase in publications concerning the topic of rotator cuff repair, there are still controversies regarding surgical technique.

OBJECTIVES

The aim of this work is to present an overview of the recently published results of biomechanical and clinical studies on rotator cuff repair using single- and double-row techniques.

MATERIALS AND METHODS

The review is based on a selective literature research of PubMed, Embase, and the Cochrane Database on the subject of the clinical and biomechanical results of single- and double-row repair.

RESULTS

In general, neither the biomechanical nor the clinical evidence can recommend the use of a double-row concept for the treatment for every rotator cuff tear. Only tears of more than 3 cm seem to benefit from better results on both imaging and in clinical outcome studies compared with the use of single-row techniques.

CONCLUSIONS

Despite a significant increase in publications on the surgical treatment of rotator cuff tears in recent years, the clinical results were not significantly improved in the literature so far. Unique information and algorithms, from which the optimal treatment of this entity can be derived, are still inadequate. Because of the cost-effectiveness and the currently vague evidence, the double-row techniques cannot be generally recommended for the repair of all rotator cuff tears.

Growth factor expression after supraspinatus tear: a quantitative polymerase chain reaction (PCR) study in rats

INTRODUCTION

The objective of this study was to evaluate the temporal expression pattern of three different growth factors (VEGF, IL-1β, and TGF-1β) in a supraspinatus tendon lesion in an animal model. The hypothesis of this study is that there are variations in the expression of these factors in the first 8 weeks after injury.

MATERIALS AND METHODS

A full thickness defect was made in the supraspinatus tendon of 40 rat shoulders. The animal were sacrificed at 0, 3, 7, 14 and 56 days after injury and three tissue samples were obtained: bone from the tendon footprint; the supraspinatus tendon stump, and a fragment of the myotendinous junction. After mRNA extraction, quantitative PCR analysis was performed, and the expression of three different growth factors were evaluated in each zone.

RESULTS

There was an increased expression of IL-1β during the first week after injury at all levels evaluated with a clear peak in the first day after injury. There was also a significant increase in TGF-1β expression levels all along the first week in the three zones. There were no variations in VEGF expression in the three zones along the 8 weeks.

CONCLUSION

IL-1β was expressed predominantly in the initial stages after injury; TGF initiated its expression after the initial phase since day three, whereas VEGF remained basically unchanged during the entire process.

Summary of Meta-Analyses Dealing with Single-Row versus Double-Row Repair Techniques for Rotator Cuff Tears

Background:

Several meta-analyses of randomized clinical trials have been performed to analyze whether double-row (DR) rotator cuff repair (RCR) provides superior clinical outcomes and structural healing compared to single-row (SR) repair. The purpose of this study was to sum up the results of meta-analysis comparing SR and DR repair with respect on clinical outcomes and re-tear rates.

Methods:

A literature search was undertaken to identify all meta-analyses dealing with randomized controlled trials comparing clinical und structural outcomes after SR versus DR RCR.

Results:

Eight meta-analyses met the eligibility criteria: two including Level I studies only, five including both Level I and Level II studies, and one including additional Level III studies. Four meta-analyses found no differences between SR and DR RCR for patient outcomes, whereas four favored DR RCR for tears greater than 3 cm. Two meta-analyses found no structural healing differences between SR and DR RCR, whereas six found DR repair to be superior for tears greater than 3 cm tears.

Conclusion:

No clinical differences are seen between single-row and double-row repair for small and medium rotator cuff tears after a short-term follow-up period with a higher re-tear rate following single-row repairs. There seems to be a trend to superior results with double-row repair in large to massive tear sizes.