Biomechanical and histological analysis after tenotomy of the long head of the biceps in the rabbit shoulder model

Arthroscopic Biceps Tenotomy Using a Single Portal for Working and Viewing: A Rabbit Model and Technique

Biceps tenotomy (BT) is a common surgery used to address anterior shoulder pain and joint dysfunction in humans. Using animal models to simulate human conditions is an effective and essential research strategy to further understand histologic and biomechanical processes that occur after BT, including the pathology of the detached biceps, secondary tendinopathic conditions of the rotator cuffs, and glenohumeral functional changes. This Technical Note presents a comprehensive step-by-step description of an arthroscopic BT procedure in rabbits. This technique is particularly beneficial, as the mini-invasive arthroscopic technique in a rabbit model is similar to that performed in humans. which resulted in less scarring and injuries to other adjacent structures in comparison with open surgery.

The Biomechanical and Histological Processes of Rerouting Biceps to Treat Chronic Irreparable Rotator Cuff Tears in a Rabbit Model

BACKGROUND

Recently, the biceps was rerouted into a newly fabricated bicipital groove for in situ superior capsular reconstruction (SCR), resulting in promising time-zero cadaveric and clinical outcomes. However, no studies have determined the in vivo biomechanical and histological processes after the biceps is transposed to a nonanatomic position.

PURPOSE

To explore the in vivo biomechanical and histological processes of the rerouting biceps tendon to treat chronic irreparable rotator cuff tears (IRCTs) in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 94 skeletally mature male rabbits were used to create a chronic IRCT model in the supraspinatus tendon. Then, the biceps rerouting procedures were performed in rabbits with chronic IRCT. Eighteen rabbits were sacrificed at 1, 3, 6, 9, and 12 weeks postoperatively for biomechanical testing, micro-computed tomography scanning, and histological analysis. The biomechanical and histological changes of intra- and extra-articular portions of the rerouting biceps were evaluated at each time point, with the contralateral native superior capsule (NSC) and the native biceps (NB) as controls, respectively. The morphology and bone formation of the fabricated bicipital grooves were evaluated, with native grooves as controls.

RESULTS

The intra-articular rerouting biceps tendon was progressively remodeled over time, displaying denser fibers and more mature collagen than those of the NSC, with gradual improvements in the tendon-to-bone healing interface from 6 to 12 weeks. Consequently, the failure load and stiffness of the intra-articular rerouting biceps portion increased with time and were significantly higher than those of the NSC from 9 weeks. Similarly, the extra-articular portion of the rerouting biceps progressively healed into a new bicipital groove, as demonstrated by a smaller tendon-to-bone interface from 6 to 12 weeks, resulting in greater failure load and stiffness at 9 and 12 weeks than those of the NB attachment. The newly fabricated bicipital groove showed similar morphology to that of the native groove with sufficient trabecular bone formed underneath.

CONCLUSION

The rerouting biceps could progressively remodel and heal into the newly fabricated bicipital groove over time, resulting in greater biomechanical performances in intra- and extra-articular portions than the NSC and the NB attachment.

CLINICAL RELEVANCE

The biceps rerouting technique may be a feasible procedure to perform in situ SCR to treat IRCT in the future clinical practice; however, more clinical evidence is required.

Long Head of the Biceps Tendon Tenotomy versus Subpectoral Tenodesis in Rotator Cuff Repair

Backgroud

Lesions of the long head of the biceps tendon (LHBT) are one of the most common pathologies in patients with a rotator cuff tear. Although various procedures have been shown to be effective for treating LHBT lesions during rotator cuff repair, no consensus has been reached regarding the most effective treatment. The purpose of this study was to compare the outcomes of tenotomy vs subpectoral tenodesis of the LHBT in arthroscopic rotator cuff repair.

Methods

The records of 135 patients who underwent arthroscopic rotator cuff repair with biceps tenotomy or subpectoral tenodesis for a partial LHBT tear of > 50% were initially reviewed. Finally, 77 patients (38 patients with tenotomy and 39 patients with subpectoral tenodesis) with an intact rotator cuff, who underwent a functional evaluation at 1 year postoperatively, were enrolled in this retrospective study.

Results

The average follow-up was 13.3 ± 4.36 months (13.2 ± 1.4 months in the tenotomy group and 13.6 ± 2.7 months in the subpectoral tenodesis group; p = 0.416). Demographic and surgical data were not significantly different between the 2 groups. Preoperatively, biceps groove tenderness, Speed's test, and Yergason test results were positive in 27.3%, 27.3%, and 10.4% of the study subjects, respectively. Compared with preoperative values, all functional scores including shoulder muscle power were significantly improved postoperatively, and no significant intergroup difference was observed (all p > 0.05). A visible Popeye deformity was not encountered in either group at the final follow-up. Eight patients in the tenotomy group and 7 patients in the subpectoral tenodesis group complained of mild anterior shoulder pain (p = 0.731), and 4 patients in each group complained of groove tenderness (p = 0.969). No surgical or postoperative complication occurred in either group.

Conclusions

Both biceps tenotomy and subpectoral tenodesis performed during rotator cuff repair improved pain and function and resulted in comparable clinical outcomes. Residual symptoms associated with the remnant LHBT in the groove may not be a problem after adhesion of LHBT.

Novel implant-free loop Tenodesis vs. simple Tenotomy of the long biceps tendon - a biomechanical investigation

Background

Simple tenotomy and anchor tenodesis are commonly used in treatment of long biceps tendon (LHB) pathologies. The tenotomy can result in biceps distalization or cosmetic deformities. A novel loop Tenodesis Technique (LTD) could prevent a distalization of the biceps muscle without the risk of implant associated complications. The purpose of this study was to investigate the biomechanical aspects of the novel LTD compared to a standard tenotomy of the LHB. It has been hypothesized that the novel technique will show biomechanical superiority in terms of resistance and distalization.

Methods

Seven paired adult human cadaveric shoulder joints were assigned to one of the two study groups: Loop tenodesis (LTD); simple tenotomy (STT). In both groups load-to-failure testing was performed. The load-displacement curve was used to determine the maximum load (N), the degree of distalization of the LHB (mm) and the stiffness (N/mm). Additionally, the mode of failure was registered.

Results

The LTD group achieved a significantly higher ultimate load to failure (LTD: 50.5 ± 12.5 N vs. STT: 6.6 ± 3.9 N; p = 0.001). Significantly less distalization of the tendon could be detected for the LTD group (LTD: 8 ± 2.3 mm vs. STT: 22.4 ± 2.4 mm; p = 0.001). Stiffness was 7.4 ± 3.9 N/mm for the LTD group and 0.23 ± 0.16 N/mm for the STT group (p = 0.001). In all specimens of the LTD group a tendon rupture was found as mode of failure, while the STT group failed because of pulling out the LHB through the bicipital groove.

Conclusion

The novel loop Tenodesis Technique shows biomechanically higher stability as well as less distalization compared to a simple tenotomy of the long biceps tendon.

Distal Pullout Strengths of the Biceps Long Head Tendon for Different Adjacent Tissue and Tendon Pathologies during Rotator Cuff Repair

Purpose. Pathologies of the long head of the biceps tendon (LHBT) are frequently recognized in cases of rotator cuff tear. Recommendations for managing such pathologies remain debatable, and distal migration of tenotomized biceps is always a concern when only tenotomy is performed. Methods. Seventy patients of mean age 60.4 ± 6.9 years (range: 44 to 82 years) were included in this retrospective study. During subpectoral tenodesis in rotator cuff repair, pullout tensions were measured using a digital tensiometer. Measured tensions obtained were analyzed with respect to sex, tear involvement of the subscapularis, and the presence of a partial tear of LHBT, type II SLAP lesion, subluxation/dislocation of the biceps, or a pulley lesion. Results. Mean LHBT pullout tension for the 70 study subjects was 86.5 ± 42.1 N (26.7-240.5 N). Distal LHBT pullout tension was significantly greater for men than women (93.2 ± 42.7 N versus 73.7 ± 38.7 N, P = 0.041). However, LHBT pullout tensions were not significantly associated with different pathologies of surrounding tissues or of LHBTs (all Ps > 0.05). Conclusion. The study failed to show pullout tension differences associated with pathologies affect distal migration of a tenotomized LHBT. Gender was the only factor found to affect LHBT pullout strength. Risk of distal migration of tenotomized LHBT could not be predicted with intraoperative arthroscopic pathologic findings.

Histological Changes in Biceps Muscle after Tenotomizing the Biceps Long Head in a Rat Model

Background

Popeye deformity is common after rupture of the biceps muscle’s long head tendon. Herein, we report on histological changes in biceps brachii muscles following tenotomy of the long head biceps tendon.

Methods

Twelve Sprague-Dawley rats (12-week-old) underwent tenotomy of the long head biceps tendon in the right shoulder. At postoperative weeks 4, 7, and 10, the operative shoulders were removed by detaching the biceps brachii muscle from the glenoid scapula and humerus; the opposite shoulders were removed as controls. H&E staining was performed to elucidate histological changes in myocytes. Oil-red O staining was performed to determine fatty infiltration. Myostatin antibody immunohistochemistry staining was performed as myostatin is expressed by skeletal muscle cells during myogenesis.

Results

H&E staining results revealed no changes in muscle cell nuclei. There were no adipocytes detected. Compared with that of the control biceps, the cross-sectional area of the long head biceps was significantly smaller (p=0.00). Statistical changes in the total extent of the 100 muscle cells were significant (p=0.00). Oil-red O staining revealed no fatty infiltration. Myostatin antibody immunohistochemical staining revealed no significant difference between the two sides.

Conclusions

Muscular changes after tenotomy of the long head biceps included a decrease in the size of the individual muscle cells and in relative muscle mass. There were no changes observed in muscle cell nuclei and no fatty infiltration. Moreover, there were no changes detected by myostatin antibody immunohistochemistry assay.

[Arthroscopic tenodesis or tenotomy of the long head of the biceps tendon in preselected patients : Does it make a difference?]

BACKGROUND

Are there clinical, cosmetic and/or structural differences between tenotomy and tenodesis of the long head of the biceps tendon (LHB) in patients selected according to commonly used indication criteria?

MATERIAL AND METHODS

A total of 85 patients were included in this study. An LHB tenodesis (LHB-TD) was performed in 49 patients and a tenotomy (LHB-TT) in 36 patients. In addition to a standardized examination, the age and gender adjusted Constant score (aCS), the LHB score and the subjective shoulder value (SSV) were assessed. The cosmetic result was evaluated by both patient and examiner. In all patients the elbow flexion and supination strength were measured and compared between sides and sonography of the affected shoulder was performed.

RESULTS

Both groups showed significant differences concerning age, body mass index (BMI) and requirements for shoulder function. The aCS and the LHB score showed good to excellent results without any significant differences between the groups and the SSV also did not reveal any significant differences between the two groups. In 34 patients of the LHB-TD group and 25 patients of the LHB-TT group a mild upper arm asymmetry could be detected (n. s.). Only three patients of the LHB-TD group and two patients of the LHB-TT group confirmed the presence of a subjective popeye deformity (n. s.). Both flexion and supination strength showed significantly better results for the LHB-TD group in comparison to the LHB-TT group. The LHB could not be sonographically detected in the bicipital groove in five patients of the LHB-TD group and in one patient of the LHB-TT group.

CONCLUSION

In patients preselected according to routinely used indication parameters (e.g. age, BMI and functional requirements of the shoulder) both LHB-TD and LHB-TT can achieve good to very good functional and cosmetic results with high patient satisfaction.

Biomechanical properties of tenotomy versus biceps knot in a cadaver model

BACKGROUND

Biceps tenotomy and biceps tenodesis are the primary methods of treating biceps pathology. This study describes a new technique of tenotomy with the goal of autotenodesis to give the biceps a higher load to failure and decreased chance of a Popeye deformity.

PURPOSE

The purpose of this study was to evaluate the strength of the "biceps knot", which is an outlet tenodesis of the biceps tendon and compare the biomechanical properties of this technique to tenotomy.

METHODS

Ten matched cadaver shoulder pairs were used. In the tenotomy group, an arthroscopic tenotomy was performed at the labral biceps junction using a narrow angled biter. For the biceps knot group, a self-retrieving suture passing device was used to pass a suture as far lateral as possible. The suture was passed from just distal to the biceps insertion on the superior labrum and tied with a standard non-sliding arthroscopic knot. The humerus and biceps tendon were rigidly fixed to a materials testing machine and cyclically loaded at 10-20 N for 100 cycles at 1 Hz. After cyclic testing, a 2 N preload was placed on the tendon and the tendon was pulled in line with the bicipital groove until failure.

RESULTS

The peak load to failure for the biceps knot was 58.9 N (SEM 8.2 N) and 37.3 N (SEM 4.6 N) for the tenotomy group (p = 0.046). The average stiffness for the biceps knot group was 4.2 N/mm (SEM 0.4 N/mm) and 3.2 N/mm (SEM 0.2 N/mm) for the tenotomy group (p = 0.031).

CONCLUSION

Performing the biceps knot is a quick, easy and cost effective alternative to the current tenodesis options available.

Using the LHB score for assessment of LHB pathologies and LHB surgery: a prospective study

INTRODUCTION

The long head of biceps tendon (LHB) score was designed to clinically assess LHB pathologies. Purpose of this study was to prospectively assess patients with LHB pathologies preoperatively and after LHB surgery using the LHB score.

MATERIALS AND METHODS

Fifty-seven patients (29 f/28 m, Ø age 61.0 years), showing clinical signs of LHB pathologies, were prospectively included into this study. In 43 patients LHB pathologies could be confirmed intraoperatively. Among these, in 26 patients a biceps tenodesis (group I; 8 f/18 m, Ø age 61.2 years), and in 17 patients a biceps tenotomy was performed (group II; 12 f/5 m, Ø age 64.2 years). In 14 patients no intraoperative correlate concerning the biceps symptoms could be found (group III; 9 f/5m, Ø age 56.8 years). In these patients no further LHB treatment was carried out. The clinical evaluation contained the Constant score (CS) as well as the LHB score preoperatively and 2 years postoperatively.

RESULTS

The CS improved significantly in all the three groups [group I: 41.7 (20-70) to 81.3 (62-100); group II: 42.2 (18-66) to 75.3 (41-84); group III: 45.7 (22-77) to 72.9 (48-85)] (p < 0.05). Also the LHB score increased significantly in all three groups [group I: 74.3 (41-97) to 94.2 (80-100); group II: 73.4 (57-97) to 84.2 (49-100); group III: 71.1 (58-80) to 90.8 (70-100)] (p < 0.05). Compared to group II, group I showed significant better results in the total LHB score and in the cosmetic result (p < 0.05).

CONCLUSIONS

We recommend that patients with LHB pathologies are evaluated using the LHB score, since it provides LHB related information and is a proper tool to assess the clinical outcome after surgery. However, the score is not appropriate to detect LHB pathologies preoperatively.

LEVEL OF EVIDENCE

II.