Biomechanical Comparison of the Long Head of the Biceps Tendon Versus Conjoint Tendon Transfer in a Bone Loss Shoulder Instability Model

Biomechanical Analysis Reveals Shoulder Instability With Bipolar Bone Loss Is Best Treated With Dynamic Anterior Stabilization for On-Track Lesions and With Remplissage for Off-Track Lesions

PURPOSE

To compare the biomechanical effects of augmenting Bankart repair (BR) with either remplissage or dynamic anterior stabilization (DAS) in the treatment of anterior shoulder instability with on-track or off-track bipolar bone loss.

METHODS

Eight fresh-frozen cadaveric shoulders were tested at 60° of glenohumeral abduction in the intact, injury, and repair conditions. Injury conditions included 15% glenoid bone loss with an on-track or off-track Hill-Sachs lesion as previously recommended. Repair conditions included isolated BR, BR with remplissage, and BR with DAS (long head of biceps transfer). The glenohumeral stability was assessed by measuring the anterior translation under 0, 10, 20, 30, 40, 50 N load and maximum load without causing instability at mid-range (60°) and end-range (90°) external rotation (ER). Maximum range of motion (ROM) was measured by applying a 2.2-N·m torque in passive ER and internal rotation.

RESULTS

Isolated BR failed to restore native glenohumeral stability in both on-track and off-track bipolar bone loss models. Both remplissage and DAS significantly decreased the anterior instability in the bipolar bone loss models, showing better restoration than the isolated BR. In the on-track lesions, DAS successfully restored native glenohumeral stability and mobility, whereas remplissage significantly decreased anterior translation without load (-2.12 ± 1.07 mm at 90° ER, P = .003; -1.98 ± 1.23 mm at 60° ER, P = .015). In the off-track lesions, remplissage restored native glenohumeral stability but led to significant ROM limitation (-8.6° ± 2.3° for internal rotation, P < .001; -13.9° ± 6.2° for ER, P = .003), whereas DAS failed to restore native stability at 90° ER regarding the increased anterior translation under 50 N (4.10 ± 1.53 mm, P < .001) and decreased maximum load (-13.8 ± 9.2 N, P = .021).

CONCLUSIONS

At time-zero, both remplissage and DAS significantly reduced residual anterior instability compared with isolated BR in the bipolar bone loss models and restored the native glenohumeral stability under most translational loads. However, remplissage could decrease the anterior translation without load for on-track lesions and may restrict ROM for off-track lesions, whereas DAS failed to restore native stability under high translational loads for off-track lesions.

CLINICAL RELEVANCE

DAS could be recommended to treat on-track bipolar bone loss with less biomechanical adverse effects, whereas remplissage might be the preferred procedure to address off-track bipolar bone loss for better stability.

Long head of the biceps tendon versatility in reconstructive shoulder surgery: a narrative review of arthroscopic techniques and their biomechanical principles with video presentation

The management of the long head of the biceps tendon (LHBT) during shoulder arthroscopy has been a subject of controversy for many years, with evolving discussions and trends. Despite long-standing debate, the nature of the surgical indication regarding how to treat concomitent LHBT injuries has undergone changes in recent years. It now extends beyond the timing of tenotomy to encompass considerations of alternative methods for preserving the LHBT, along with an ongoing exploration of how it can be effectively utilized in reconstructive shoulder surgery. Recent techniques describe approaches to using LHBT in a wide range of procedures, from shoulder instability to rotator cuff tears. Additionally, LHBT-based reconstructive techniques have surfaced for addressing what were formerly denoted as irreparable rotator cuff tears. While current literature provides detailed anatomical descriptions of the LHBT and many reports of novel, advanced techniques, there is still much debate regarding the decision-making process in each case. Because of the growing number of emerging techniques and the escalating debate in the subsequent paper, a decision has been made to present the current literature review concerning the potential utilization of LHBT in shoulder arthroscopy. In a dedicated video, we demonstrate the main arthroscopic techniques employed by the authors in their daily practice.

Biomechanical comparison of open Bankart repair vs. conjoint tendon transfer in a 10% anterior glenoid bone loss shoulder instability model

BACKGROUND

The treatment of shoulder instability in patients with subcritical glenoid bone loss poses a difficult problem for surgeons as new evidence supports a higher failure rate when a standard arthroscopic Bankart repair is used. The purpose of this study was to compare a conjoint tendon transfer (soft-tissue Bristow) to an open Bankart repair in a cadaveric instability model of 10% glenoid bone loss.

METHODS

Eight cadaveric shoulders were tested using a custom testing system that allows for a 6-degree-of-freedom positioning of the glenohumeral joint. The rotator cuff muscles were loaded to simulate physiologic muscle conditions. Four conditions were tested: (1) intact, (2) Bankart lesion with 10% bone loss, (3) conjoint tendon transfer, and (4) open Bankart repair. Range of motion, glenohumeral kinematics, and anterior-inferior translation at 60° of external rotation with 20 N, 30 N, and 40 N were measured in the scapular and coronal planes. Glenohumeral joint translational stiffness was calculated as the linear fit of the translational force-displacement curve. Force to anterior-inferior dislocation was also measured in the coronal plane. Repeated measures analysis of variance with a Bonferroni correction was used for statistical analysis.

RESULTS

A Bankart lesion with 10% bone loss increased the range of motion in both the scapular (P = .001) and coronal planes (P = .001). The conjoint tendon transfer had a minimal effect on the range of motion (vs. intact P = .019, .002), but the Bankart repair decreased the range of motion to intact (P = .9, .4). There was a significant decrease in glenohumeral joint translational stiffness for the Bankart lesion compared with intact in the coronal plane (P = .021). The conjoint tendon transfer significantly increased stiffness in the scapular plane (P = .034), and the Bankart repair increased stiffness in the coronal plane (P = .037) compared with the Bankart lesion. The conjoint tendon transfer shifted the humeral head posteriorly at 60° and 90° of external rotation in the scapular plane. The Bankart repair shifted the head posteriorly in maximum external rotation in the coronal plane. There was no significant difference in force to dislocation between the Bankart repair (75.8 ± 6.6 N) and the conjoint tendon transfer (66.5 ± 4.4 N) (P = .151).

CONCLUSION

In the setting of subcritical bone loss, both the open Bankart repair and conjoint tendon transfer are biomechanically viable options for the treatment of anterior shoulder instability; further studies are needed to extrapolate these data to the clinical setting.

Concomitant Biceps Tenodesis Does Not Portend Inferior Outcomes After Anterior Glenohumeral Stabilization

BACKGROUND

Military patients are known to suffer disproportionately high rates of glenohumeral instability as well as superior labrum anterior to posterior (SLAP) tears. Additionally, a concomitant SLAP tear is frequently observed in patients with anterior shoulder instability. Even though biceps tenodesis has been demonstrated to produce superior outcomes to SLAP repair in military patients with isolated SLAP lesions, no existing studies have reported on outcomes after simultaneous tenodesis and anterior labral repair in patients with co-existing abnormalities.

PURPOSE

To evaluate outcomes after simultaneous arthroscopic-assisted subpectoral biceps tenodesis and anterior labral repair in military patients younger than 40 years. We also sought to compare these outcomes with those after repair of an isolated anterior labral tear.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This study is a retrospective analysis of all military patients younger than 40 years from a single base who underwent arthroscopic anterior glenohumeral stabilization with or without concomitant biceps tenodesis between January 2010 and December 2019. Patients with glenoid bone loss of >13.5% were not eligible for inclusion. Outcome measures including the visual analog scale (VAS) for pain, the Single Assessment Numeric Evaluation (SANE), the American Shoulder and Elbow Surgeons (ASES) shoulder score, the Rowe instability score, and range of motion were administered preoperatively and postoperatively, and scores were compared between groups.

RESULTS

A total of 82 patients met inclusion criteria for the study. All patients were active-duty service members at the time of surgery. The mean follow-up was 87.75 ± 27.05 months in the repair + tenodesis group and 94.07 ± 28.72 months in the isolated repair group (P = .3085). Patients who underwent repair + tenodesis had significantly worse preoperative VAS pain (6.85 ± 1.86 vs 5.02 ± 2.07, respectively; P < .001), ASES (51.78 ± 11.89 vs 62.43 ± 12.35, respectively; P = .0002), and Rowe (26.75 ± 7.81 vs 37.26 ± 14.91, respectively; P = .0002) scores than patients who underwent isolated repair. Both groups experienced significant improvements in outcome scores postoperatively (P < .0001 for all), and there were no statistically significant differences in postoperative outcome scores or range of motion between groups. There were no differences in the percentage of patients who achieved the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptom state for the VAS pain, SANE, ASES, and Rowe scores between groups. Overall, 37 of the 40 (92.50%) patients in the repair + tenodesis group and 40 of the 42 (95.24%) patients in the isolated repair group returned to unrestricted active-duty military service (P = .6045). In addition, 38 (95.00%) patients in the repair + tenodesis group and 40 (95.24%) patients in the isolated repair group returned to preinjury levels of sporting activity (P = .9600). There were no significant differences in the number of failures, revision surgical procedures, or patients discharged from the military between groups (P = .9421, P = .9400, and P = .6045, respectively).

CONCLUSION

The findings of this study indicate that simultaneous biceps tenodesis and labral repair was a viable treatment option for the management of concomitant SLAP and anterior labral lesions in young, active military patients younger than 40 years.

The long head of the biceps tendon: a valuable tool in shoulder surgery

ANATOMY AND FUNCTION

The long head of the biceps tendon (LHBT) has different properties and characteristics that render it a valuable tool in the hands of shoulder surgeons. Its accessibility, biomechanical strength, regenerative capabilities, and biocompatibility allow it to be a valuable autologous graft for repairing and augmenting ligamentous and muscular structures in the glenohumeral joint.

SHOULDER SURGERY APPLICATIONS

Numerous applications of the LHBT have been described in the shoulder surgery literature, including augmentation of posterior-superior rotator cuff repair, augmentation of subscapularis peel repair, dynamic anterior stabilization, anterior capsule reconstruction, post-stroke stabilization, and superior capsular reconstruction. Some of these applications have been described meticulously in technical notes and case reports, whereas others may require additional research to confirm clinical benefit and efficacy.

CONCLUSION

This review examines the role of the LHBT as a source of local autograft, with biological and biomechanical properties, in aiding outcomes of complex primary and revision shoulder surgery procedures.

Onlay Dynamic Anterior Stabilization With Biceps Transfer for the Treatment of Anterior Glenohumeral Instability Produces Good Clinical Outcomes and Successful Healing at a Minimum 1 Year of Follow-Up

Purpose

To report the results of the onlay dynamic anterior stabilization (DAS) using the long head of biceps (LHB) and the double double-pulley technique for the treatment of anterior glenohumeral instability (AGI) with ≤20% glenoid bone loss (GBL).

Methods

From September 2018 to December 2021, patients with AGI and ≤20% GBL were enrolled in a prospective study on DAS and followed for a minimum of 1 year. The primary outcomes were Western Ontario Shoulder Instability Index, Rowe score, range of motion, and strength. The secondary outcomes were ability to return to play (RTP), RTP at same level, lack of recurrence of instability, successful LHB healing, and lack of complications. Magnetic resonance imaging was used to measure GBL, Hill-Sachs interval, glenoid track, and assess LHB integrity.

Results

Eighteen consecutive patients underwent DAS. Fifteen patients had a minimum follow-up of 12 months (mean, 23.93 ± 13.67 months). In total, 12 were male and 3 female patients; 73.3% practiced recreational sports; mean age at surgery was 23.40 ± 6.53 years; mean number of dislocation episodes were 10.13 ± 8.42; mean GBL was 8.21 ± 7.39% (range, 0-20.24%); mean Hill-Sachs interval was 15.00 ± 2.96 mm; and mean glenoid track was 18.87 ± 2.57mm. The mean improvement in the Western Ontario Shoulder Instability Index and Rowe score (959.27 ± 386.70 and 74.00 ± 22.22 points) was significant (P < .001 and P < .001) and more than 6 times greater than the minimum clinically important difference. The mean improvement in active elevation, abduction, and external and internal rotation (23.00 ± 27.76°, 33.33 ± 43.78°, 8.33 ± 13.58°, and 0.73 ± 1.28 points) was significant (P = .006, P = .011, P = .032, and P = .044). RTP rate was 93.33%. RTP at same level was 60.00%. One patient with hyperlaxity had a redislocation (6.7% recurrence). No complications were reported. Each magnetic resonance imaging scan showed successful LHB healing to the anterior glenoid.

Conclusions

At a minimum of 1-year follow-up, DAS produces significant and clinically important improvements in shoulder function, successful LHB healing, and is safe for the treatment of AGI with ≤20% GBL without severe hyperlaxity.

Level of Evidence

IV, therapeutic case series.

Arthroscopic Dynamic Anterior Stabilization Using Either Long Head of the Biceps or Conjoined Tendon Transfer for Anterior Shoulder Instability Results in a Similarly Low Recurrence Rate

PURPOSE

To compare the clinical outcomes of arthroscopic dynamic anterior stabilization (DAS) between transferring the long head of the biceps (DAS-LHB) and the conjoined tendon (DAS-CT) for anterior shoulder instability with <15% glenoid bone loss.

METHODS

From January 2016 to May 2019, a total of 63 patients who underwent DAS for recurrent anterior shoulder dislocation with <15% glenoid bone loss were included, comprising 33 patients in DAS-LHB group and 30 patients in DAS-CT group. Clinical outcomes were assessed preoperatively and at a minimum 3-year follow-up, including patient-reported outcomes, range of motion, and return to sports (RTS). Postoperative recurrent instability (including dislocation, subluxation, and subjective instability with a positive apprehension test), revisions and complications also were recorded.

RESULTS

No significant demographic characteristics difference was detected between the DAS-LHB (26.3 ± 7.9 years) and DAS-CT groups (26.0 ± 6.7 years). At the latest follow-up, there were no significant differences between the 2 groups in functional scores: Oxford Shoulder Instability Score (14.8 ± 2.8 vs 15.2 ± 3.6), Rowe score (95.9 ± 6.5 vs 93.2 ± 10.2), visual analog scale for pain (0.8 ± 1.2 vs 0.7 ± 1.7), and American Shoulder and Elbow Surgeons (95 ± 8.8 vs 95.2 ± 9.1) (all P > .218). No significant difference was detected between groups in the rates of RTS (90.1% vs 86.7%, P = .700) and RTS at previous level (78.7% vs 73.3%, P = .258), respectively. No recurrent dislocation occurred in either group. One patient felt occasional subluxation in the DAS-LHB group, and one was positive for the apprehension test in each group. One patient presented with postoperative shoulder stiffness and underwent a secondary arthroscopic debridement in the DAS-CT group.

CONCLUSIONS

Comparable rates of recurrence, complication, return to sports, and subjective shoulder function were observed between DAS-LHB and DAS-CT groups.

LEVEL OF EVIDENCE

Ⅲ; retrospective comparative therapeutic trial.

Clinical and Radiological Outcomes in Patients With Anterior Shoulder Instability and Glenoid Bone Loss after Arthroscopic Free Bone Block Combined With Dynamic Anterior Stabilization

BACKGROUND

As an alternative to the Latarjet procedure, the arthroscopic free bone block (FBB) procedure combined with dynamic anterior stabilization (DAS) has been recently proposed to provide both glenoid augmentation and a tendon sling effect for treating anterior shoulder instability (ASI) with glenoid bone loss.

PURPOSE

To evaluate the clinical and radiological outcomes of FBB-DAS for ASI with glenoid bone loss.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent arthroscopic FBB-DAS for ASI with >15% glenoid bone loss between February 2017 and March 2020 were screened and enrolled in this study. Clinical outcome measures were assessed preoperatively and at a minimum 2-year follow-up, including recurrence, complications, shoulder functional scores, range of motion, and return to sports. Postoperative computed tomography and magnetic resonance imaging were also performed.

RESULTS

Of a total of 65 patients with a mean follow-up of 46.1 ± 13.1 months, no patients experienced a recurrent dislocation or subluxation postoperatively, while 2 had a positive anterior apprehension test (3.1%). Additionally, 2 patients (3.1%) experienced complications of hematoma and shoulder stiffness, respectively. The mean visual analog scale score, American Shoulder and Elbow Surgeons score, Rowe score, and Oxford Shoulder Instability Score all improved significantly from 3.2 ± 2.4, 75.0 ± 18.9, 43.6 ± 27.3, and 33.8 ± 9.0 preoperatively to 1.3 ± 0.8, 95.1 ± 8.0, 95.5 ± 7.8, and 14.8 ± 3.5 at final follow-up, respectively (all P < .001). No difference was detected in range of motion except for 8.1° and 7.5° external rotation limitations in adduction and abduction, respectively. There were 62 patients (95.4%) who returned to sports, and 54 patients (83.1%) returned to the preinjury level. The transferred biceps tendon was intact in all 59 patients who completed radiological examination at the latest follow-up. Good bone healing was achieved in 98.3% of patients, and the glenoid bone defect decreased from 18.1% to 4.9%. Osseous and labral glenoids were significantly enlarged in width and depth on the latest magnetic resonance imaging (all P < .001).

CONCLUSION

Arthroscopic FBB-DAS provided satisfactory clinical and radiological outcomes for ASI with glenoid bone loss. Despite slight external rotation restrictions, it achieved low recurrence and complication rates, excellent shoulder functional scores, a high return-to-sports rate, and favorable graft healing and remodeling.

Biomechanical analysis of anterior stability after 15% glenoid bone loss: comparison of Bankart repair, dynamic anterior stabilization, dynamic anterior stabilization with Bankart repair, and Latarjet

BACKGROUND

Dynamic anterior shoulder stabilization (DAS) with Bankart repair is a recently described stabilization technique thought to be more robust than an isolated Bankart repair while avoiding many coracoid transfer-related complications and technical demands. DAS involves transfer of the long head biceps through a subscapularis split to the anterior glenoid to create a sling effect. We hypothesize that DAS with Bankart repair will restore anterior stability in a human-cadaveric model with subcritical (15%) glenoid bone loss.

METHODS

Eight cadaveric shoulders were tested using an established shoulder simulator to record glenohumeral translations with an accuracy of ±0.2 mm. Shoulders were tested in 5 states-intact soft tissues, Bankart defect with 15% bone loss, isolated Bankart repair, DAS with Bankart repair, isolated DAS, and Latarjet. A 45 N anterior force was applied through the pectoralis major tendon, and translation of the humeral head was recorded and compared with repeated measures analysis of variance.

RESULTS

The anterior translation in the intact (native) glenoid was 4.7 mm at neutral position and 4.6 mm at 45° external rotation. Anterior translation significantly increased after introducing a Bankart defect with 15% glenoid bone loss to 9.1 mm (neutral, P = .002) and 9.5 mm (45° external rotation, P < .001). All repair conditions showed a significant decrease in anterior translation relative to Bankart defect. DAS with Bankart repair decreased anterior translation compared with the Bankart defect: 2.7 mm (neutral, P < .001) and 2.1 mm (45° external rotation, P < .001). DAS with Bankart repair significantly decreased anterior translation compared with the isolated Bankart repair (2.7 mm vs. 4.7 mm, P = .023) and the isolated DAS (2.7 mm vs. 4.3 mm, P = .041) in neutral position. The Latarjet procedure resulted in the greatest reduction in anterior translation compared with the Bankart defect: 1.2 mm (neutral, P < .001) and 1.9 mm (45° external rotation, P < .001).

CONCLUSIONS

DAS with Bankart repair is a viable alternative to restore anterior glenohumeral stability with a 15% glenoid defect at a greater degree than either DAS or Bankart repair alone. The Latarjet procedure was the most effective in reducing anterior translation but restrained the anterior translation significantly more than the native glenoid.

Early Treatment of Shoulder Pathology Is Necessary but Not Enough Is Being Performed

Delayed treatment of shoulder instability results in bone loss requiring more-complicated surgery, in turn resulting in less-optimal outcomes. Similarly, delayed treatment of repairable rotator cuff tears results in irreparable tears requiring more-complicated surgery and resulting in less-optimal outcomes. Delayed treatment of shoulder pathology is a problem. Solutions include education and research investigation.

Dynamic Anterior Stabilization Using Transosseous Bone Tunnel Technique With the Adjustable Loop Length Cortical Button Incorporating High-Strength Suture Augmentation for Recurrent Shoulder Instability

Dynamic anterior stabilization using the long head of the biceps tendon is a recently described technique in the management of recurrent shoulder dislocation with subcritical bone loss. This technique involves the transfer of the long head of the biceps to the glenoid, providing sling and hammock effect. The long head of the biceps (LHB) tendon fixation can be accomplished with a variety of implants. We present a modified fixation technique of LHB tendon using transosseous bone tunnel with the adjustable loop length cortical button, incorporating high-strength suture augmentation device in a patient with recurrent glenohumeral instability with limited glenoid bone loss and an engaging Hill-Sachs defect in the humeral head.

Bankart Repair With Transferred Long Head of the Biceps Provides Better Biomechanical Effect Than Conjoined Tendon Transfer in Anterior Shoulder Instability With 20% Glenoid Defect

PURPOSE

To examine the biomechanical differences between labral repair with transferred conjoined tendon and transferred long head of the biceps tendon (LHBT) for anterior shoulder instability with 20% bone loss.

METHODS

Twelve cadaveric shoulders were tested in sequent 5 conditions: intact, 20% glenoid defect, Bankart repair, Bankart repair with transferred conjoined tendon (dynamic conjoined tendon sling, DCS), and with transferred LHBT (dynamic LHBT sling, DLS) at 60° of glenohumeral abduction and 60° of external rotation. The physiological glenohumeral joint load was created by forces applied to the rotator cuff, conjoined tendon, and LHBT. The glenohumeral compression force and range of motion were recorded before anteroinferior force application. The anterior, inferior, and total translations were measured with 20, 30, 40, and 50 N of anteroinferior force, respectively.

RESULTS

Anteroinferior glenoid defect led to significant increase of humerus translation and decrease of glenohumeral compression force. DLS provided better resistance effect in both anterior-posterior and superior-inferior directions than DCS under high loading condition (40 N, P =.03; 50 N, P <.01). Both DCS and DLS procedures could further restore glenohumeral compression force with Bankart repair (Bankart repair: 32.1 ± 4.0 N; DCS: 36.7 ± 3.2 N, P < .01; DLS: 35.8 ± 3.6 N, P =.03). No range of motion restrictions were observed relative to the normal shoulder.

CONCLUSIONS

Both the DLS and DCS techniques could reduce the anterior-inferior translation and partially restore the glenohumeral stability in anterior shoulder instability with 20% anteroinferior glenoid defect compared with Bankart repair. Under greater loading conditions, DLS provides better stability than DCS.

CLINICAL RELEVANCE

Shoulder stability can be restored by DLS and DCS with low load. With greater shoulder stability requirements, DLS might be a better option than DCS for anterior shoulder instability with 20% bone loss.

Arthroscopic Subscapularis Tendon Repair Using the Mason-Allen Technique

BACKGROUND

Arthroscopic rotator cuff repair has recently been popularized for treating tears. In a biomechanical trial, the Mason-Allen stitch improved the fixation quality of poorly vascularized tendons. The use of this technique involving the subscapularis tendon remains rare. The aim of this study was to evaluate the clinical outcomes of Mason-Allen technique repaired subscapularis tendons.

METHODS

A retrospective research of collected data from 98 patients with subscapularis tears who had undergone arthroscopic repair between May 2015 and December 2018. There were 75 males and 23 females. The mean age was 56.4 ± 9.6 years and the mean follow-up was 12.5 ± 4.0 months. The visual analog scale (VAS), American Shoulder and Elbow Surgeons (ASES) score, and Constant-Murley score were used to analyze shoulder function. An MRI was performed to assess the integrity of the repair.

RESULTS

Patients had significantly less pain and a better active range of motion compared with preoperative levels. VAS improved significantly from a preoperative mean of 3.42 to a postoperative mean of 1.91. ASES increased significantly from the preoperative mean of 43.6 to the postoperative mean of 74.5. Seven cases suffered from retears, which were confirmed by an MRI examination.

CONCLUSION

Arthroscopic rotator cuff repair with the Mason-Allen method resulted in a decreased level of pain and satisfied function recovery.

Editorial Commentary: Double-Sling Transfer of Both the Conjoined Tendons and Long Head Biceps Tendon for Glenoid Bone Loss in Patients With Shoulder Instability Shows Biomechanical Benefit in Shoulder Abduction and External Rotation But May Be Insufficient in Mid-Range Arm Positions

Recurrence of shoulder glenohumeral instability is exacerbated in cases of glenoid bone loss. Surgical bone transfer techniques well address the issue. Innovative soft-tissue tendon transfers may fill the defect plus provide a sling effect. Double-sling transfer of both the conjoined tendons and long head biceps tendon for glenoid bone loss in patients with shoulder instability shows biomechanical benefit in shoulder abduction and external rotation. However, as the sling effect is less pronounced in mid-range arm position, the benefit of double-sling transfer may be insufficient. Moreover, the biomechanical models are limited relative to the complexity of clinical glenohumeral function, and obviously limited to time-zero analysis. We should be careful before we abandon bony augmentation procedures.

Long head of biceps transfer to augment Bankart repair in chronic anterior shoulder instability with and without subcritical bone loss: a biomechanical study

BACKGROUND

Treating recurrent anterior shoulder instability in participants in collision sports, patients with capsulolabral defects, and patients with bipolar bone loss remains challenging. The study purpose was to investigate the effect of long head of the biceps transfer (LHBT) on load-to-dislocation biomechanics in a repetitive serial shoulder dislocation cadaveric model comparing LHBT with the Latarjet and Bankart procedures-the first-line treatment methods for chronic traumatic anterior shoulder instability with and without anterior glenoid bone loss, respectively.

METHODS

In this controlled laboratory study, 8 fresh-frozen cadaveric shoulders with different conditions were dislocated in sequence using a custom test frame. The muscle loading configuration simulated the arm in the apprehension position, and biceps loads of 20 N and 40 N were used for the static glenohumeral position analysis to evaluate the sling effect. Sequential experimental conditions consisted of the intact state, second and third dislocations, chronic instability, Bankart repair, first LHBT, subcritical glenoid bone loss, second LHBT, and Latarjet procedure.

RESULTS

The pectoralis major and joint reaction loads to dislocation sequentially decreased with serial dislocations in all specimens, with the lowest value in the subcritical glenoid bone defect condition. In the setting of chronic instability, the pectoralis load to dislocation was significantly higher with the Bankart repair (P = .031) and LHBT (P < .001), at 71% and 85% of the intact value, respectively. Direct comparison of the pectoralis load to dislocation favored LHBT over Bankart repair (P = .015). In the subcritical defect scenario, LHBT did not significantly increase the load to dislocate, and the Latarjet procedure demonstrated a higher load to dislocate than LHBT (P < .001). All 3 surgical procedures tested significantly increased the angle of horizontal abduction at the time of dislocation and restored the glenohumeral position to closer to the intact state. Doubling the biceps load leveraged the sling effect, pulling the humeral head farther posterior-superiorly, but this was not enough to overcome the effect of a 20% subcritical glenoid bone defect.

CONCLUSIONS

In a serial dislocation model, LHBT effectively stabilized the glenohumeral joint in a simulated chronic instability scenario, increasing the pectoralis major load-to-dislocate and glenohumeral joint reaction force components at the time of dislocation and restoring relative glenohumeral positioning to close to the intact state. The Latarjet procedure outperformed LHBT in stabilizing shoulders in the 20% subcritical glenoid bone defect condition.

Dynamic Double-Sling Augmentation Prevents Anteroinferior Translation for Recurrent Anteroinferior Shoulder Dislocation With 20% Glenoid Bone Loss: A Cadaveric Biomechanical Study

PURPOSE

To biomechanically compare the dynamic double-sling with single-sling augmentation using the conjoined tendon (CT) with 20% of an anteroinferior glenoid bone defect under the high loads in shoulders.

METHODS

With the shoulder in 60° of glenohumeral abduction and 60° of external rotation, the 12 shoulders stability was tested sequentially in 5 conditions: intact, 20% glenoid bone loss, Bankart repair, single-sling augmentation with the CT, and double-sling augmentation with both the CT and long head of the biceps tendon (LHBT). The anteroinferior humeral head (HH) translation force of 20N, 30N, 40N, 50N, or 60N was applied to determine the shoulder stability in each condition.

RESULTS

The total HH translation over 8.77 mm represented the anteroinferior shoulder instability (95% confidence interval of bone defect: 7.76-8.77 mm). A significant increase in anteroinferior HH translation was demonstrated after the creation of 20% glenoid bone defect under the 20N translational force (10.52 ± 0.71 mm). Structural failure after the Bankart repair and the single-sling augmentation under the 30N (9.84 ± 1.25 mm) and 40N (9.59 ± 0.66 mm) translational forces, respectively, were observed. The double-sling augmentation effectively prevented the anteroinferior HH translation under the translational force of less than 40N, and only half of the augmentation structure (8.25 ± 1.66 mm) had failed under the 50N translational forces.

CONCLUSION

In the absence of any Hill-Sachs lesion and when tested at 60° abduction and external rotation in shoulders with 20% glenoid bone defects, at time-zero, the double-sling augmentation strategy could effectively prevent anteroinferior translation when compared with the Bankart repair or the single-sling augmentation technique under all magnitudes of the translational force in biomechanical simulation. Nevertheless, none of the constructs restored the HH translation to the normal intact state.

CLINICAL RELEVANCE

Double-sling augmentation technique may represent a reliable option for preventing anteroinferior translation.

Arthroscopic Subscapularis Augmentation Using the Long Head of the Biceps Tendon for Anterior Shoulder Instability

The limitations of transferring the coracoid process along with the conjoined tendon are coracoacromial arch damage, technical difficulty, and nerve injury. The long head of the biceps tendon (LHBT) proximal transposition technique has a weaker sling effect and a risk of nerve injury. The arthroscopic subscapularis augmentation technique may have risks of shoulder external rotation restriction and subscapularis transection. Herein, we introduce an arthroscopic technique for the transfer of the LHBT for subscapularis augmentation to address these risks. Indications of this technique were patients younger than 45 years of age who engage in competitive sports, require forceful external rotation and abduction, have a related capsule-ligament insufficiency, and have a glenoid bone loss <25%. The steps include detaching the LHBT at the upper edge of the pectoralis major, transecting and braiding the LHBT, establishing a scapular tunnel, placing a guide suture through the upper third of the subscapular and scapular tunnel, passing the LHBT through the established tunnels, and fixating the LHBT. This technique achieves stability of the anterior shoulder by transecting and transferring the distal end of the LHBT to press on the upper third of the subscapularis muscle.

Extra-articular Soft Arthroscopic Latarjet Technique: More Versatility and Closer Reproducibility of Classic Latarjet Procedure than Its Intra-articular Counterpart

The recent innovative concept of dynamic anterior stabilization of the shoulder by long head of biceps tendon for anterior gleno-humeral instability management has gained growing popularity among shoulder surgeons. Different techniques using this concept have been reported. Nevertheless, these techniques share common steps of tenotomy, re-routing, trans-subscapularis transfer and bony glenoid fixation of long head of biceps. Lately, a simplified procedure of intra-articular soft arthroscopic Latarjet technique has been introduced to refer to soft tissue tenodesis of long head of biceps to subscapularis tendon by 2 simple stitches of nonabsorbable sutures following Bankart repair. For more technical simplicity and closer reproducibility of gleno-humeral restabilization mechanisms of Latarjet procedure; the current Technical Note describes the extra-articular soft arthroscopic Latarjet technique, whereby long head of biceps is retrieved to the subpectoral region following intra-articular tenotomy; whip-stitched; rerouted deep to pectoralis major; and passed within subscapularis window into the gleno-humeral joint, where it is sutured over itself around upper subscapularis tendon. The currently reported technique offers potential advantages of versatility, steep learning curve, low cost (no hardware), feasibility of concurrent gleno-humeral restabilization procedures, and technical easiness of revision management; however; it is nonanatomic and should be biomechanically and clinically investigated to validate its long-term versatile utility.

Double-Sling Augmentation for Anterior Shoulder Dislocation

Anterior capsule ligament deficiency occurs in complicated anterior shoulder dislocation and poses a challenge to surgeons because of the irreparability of the capsule labrum structure or the nonoptimal healing potential after repair. Single-sling augmentation with either conjoined tendon or the long head of the biceps brachii has been reported to enhance the anterior stability of the shoulder. However, single-sling augmentation may still not be enough in cases of complicated anterior shoulder dislocation. Thus we introduce a double-sling anterior shoulder augmentation technique in which both the conjoined tendon and the long head of the biceps brachii are transferred to the anterior inferior side of the glenoid. Our clinical experience indicates that this procedure is effective to address complicated anterior shoulder dislocation. We believe that the introduction of this technique will provide a special choice in the treatment of anterior shoulder dislocation.

Four-Layer Structural Reconstruction for Recurrent Anterior Shoulder Dislocation

Recurrent anterior shoulder dislocation is always combined with glenoid and capsule-labrum deficiency. To address all these deficiency in a single operation, we developed a 4-layer structural reconstruction technique at the anterior side of the shoulder, which includes capsule-labrum repair, glenoid bone grafting, and transfer of the long head of the biceps brachii (LHB). This procedure is indicated in patients who need both sling and bone fragment augmentation. The critical steps of this technique are LHB transfer and 2-layer glenoid bone grafting. We believe that this technique will enhance the field of anterior shoulder reconstruction for complicated anterior shoulder dislocation.

Shoulder biomechanics in normal and selected pathological conditions

The stability of the glenohumeral joint depends on soft tissue stabilizers, bone morphology and dynamic stabilizers such as the rotator cuff and long head of the biceps tendon. Shoulder stabilization techniques include anatomic procedures such as repair of the labrum or restoration of bone loss, but also non-anatomic options such as remplissage or tendon transfers.

Rotator cuff repair should restore the cuff anatomy, reattach the rotator cable and respect the coracoacromial arch whenever possible. Tendon transfer, superior capsular reconstruction or balloon implantation have been proposed for irreparable lesions.

Shoulder rehabilitation should focus on restoring balanced glenohumeral and scapular force couples in order to avoid an upward migration of the humeral head and secondary cuff impingement. The primary goal of cuff repair is to be as anatomic as possible and to create a biomechanically favourable environment for tendon healing.

Cite this article: EFORT Open Rev 2020;5:508-518. DOI: 10.1302/2058-5241.5.200006