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.

Salvaging the 'irreparable' tear: Superior Capsular Reconstruction augmented with partial cuff repair

Introduction Massive rotator cuff tears (MRCTs) have long posed a complex problem for both patients and surgeons. If not treated promptly, tendon retraction, fatty infiltration and muscle atrophy of the rotator cuff muscles occur. These lead to irreparable RCTs with poor functional outcomes. We describe our technique of superior capsular reconstruction (SCR) augmented with partial cuff repair and report on our short term outcomes Method Seven consecutive patients who underwent the procedure were recruited at our institution from January 2019 to December 2019. Medical records of these patients were reviewed looking at pre-operative symptoms and examination findings, imaging studies, intra-operative findings, the surgical technique employed, post-operative progress in terms of pain, affected shoulder range of movement and outcome scores. Results All patients showed complete tears of at least two tendons and were deemed irreparable intra-operatively. All patients exhibited Goutalier grade 2–4 wasting of the affected tendons on MRI and Patte grade 3 intra-operatively. At 12 months, the mean improvement shown in Constant score is 12.1 points, in University of California Los Angeles (UCLA) score is 9.4 points and in Oxford Shoulder Score is 17 points. Active forward flexion improved in all patients with a mean improvement of 40 degrees. Numerical Pain Rating Scale improved in all patients with a mean of 5.1 points. Conclusion Our case series shows good short-term outcomes can be achieved with SCR augmented with partial cuff repair. Notably, our SCR results showed encouraging results even for challenging revision rotator cuff repairs.

The Arthroscopic Intra-Articular Stabilization of the Shoulder for Irreparable Rotator Cuff Tear: A New Technique Proposal

Background: Superior capsular reconstruction (SCR) has shown good results in the management of irreparable rotator cuff tears due to the depressive effect on the humeral head, but it is a technically demanding and expensive procedure.Purpose: We hypothesized that an intra-articular neoligament that prevents the superior translation of the humeral head could give similar results in terms of the superior translation of humerus (STH) and range of motion (ROM).Study Design: To compare our proposed technique and the SCR, we conducted a biomechanical study on 10 porcine shoulders in a custom shoulder testing system.Methods: STH and total rotational ROM were quantified in the following four scenarios: (1) when the rotator cuff was intact, (2) after cutting the supraspinatus tendon, (3) after the reconstruction of the superior capsule by long head of the biceps tendon (LHB), and (4) after an arthroscopic intra-articular stabilization by an intra-articular graft. Our proposed technique provides the creation of a humeral and glenoid tunnel, the passage of a graft through these tunnels under arthroscopic guidance, and the graft fixation in the two tunnels. We analyzed the STH and total ROM in each scenario.Results: With respect to the STH, we reported that the present proposed technique is characterized by a significant reduction of superior translation at 0 and 45° compared to scenario 2. In addition, the comparison between our proposed technique and SCR showed a significant difference of the STH at 0° of abduction. Total rotational ROMs of the two tenchinques were similar to scenario 2. Therefore, the use of an intra-articular ligament that prevents the STH can restore shoulder stability in irreparable rotator cuff injuries at both 0 and 45° of glenohumeral abduction without apparently limiting the total rotational ROM.Conclusion: Our proposed technique could be an important treatment option in irreparable rotator cuff tears, especially in patients under 65 years in whom reverse shoulder arthroplasty (RSA) has shown poor results and many complications.

Shoulder Positioning during Superior Capsular Reconstruction: Computational Analysis of Graft Integrity and Shoulder Stability

The shoulder position during fixation of the graft may be a key factor impacting the outcome of arthroscopic superior capsular reconstruction (ASCR) in irreparable rotator cuff tears (IRCTs). However, biomechanical evidence regarding this effect is lacking. The aim of this study was to evaluate the influence of the shoulder position during fixation of the graft on shoulder stability and graft tear risk in ASCR. A 3-D musculoskeletal model of the upper limb was modified to account for the fixation of the graft in ASCR, assuming a full-thickness tear of the supraspinatus tendon. The concomitant tenotomy of the long head of the biceps (LHB) tendon was also studied. The biomechanical parameters evaluated included the strain of the graft and the glenohumeral joint reaction force (GH JRF), which were used to evaluate graft integrity and shoulder stability, respectively. Fixation of the graft considering abduction angles greater than 15° resulted in a high risk for graft tearing when the arm was adducted to the side of the trunk. For abduction angles below 15°, the mean shoulder stability improved significantly, ranging between 6% and 20% (p < 0.001), compared with that in the preoperative condition. The concomitant tenotomy of the LHB tendon resulted in loss of stability when compared to ASCR with an intact LHB tendon. The position of the shoulder during fixation of the graft has a significant effect on shoulder stability and graft tear risk after ASCR in IRCTs. This study provides new and important information regarding the role of shoulder positioning during fixation of the graft.