Trapezius muscle transfer for external shoulder rotation: anatomical study

Physiological Tensioning During Lower Trapezius Transfer for Irreparable Posterosuperior Rotator Cuff Tears May Be Important for Improvement in Shoulder Kinematics

BACKGROUND

Lower trapezius transfer (LTT) has been proposed for restoring the anteroposterior muscular force couple in the setting of an irreparable posterosuperior rotator cuff tear (PSRCT). Adequate graft tensioning during surgery may be a factor critical for sufficient restoration of shoulder kinematics and functional improvement.

PURPOSE/HYPOTHESIS

The purpose was to evaluate the effect of tensioning during LTT on glenohumeral kinematics using a dynamic shoulder model. It was hypothesized that LTT, while maintaining physiological tension on the lower trapezius muscle, would improve glenohumeral kinematics more effectively than undertensioned or overtensioned LTT.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 10 fresh-frozen cadaveric shoulders were tested using a validated shoulder simulator. Glenohumeral abduction angle, superior migration of the humeral head, and cumulative deltoid force were compared across 5 conditions: (1) native, (2) irreparable PSRCT, (3) LTT with a 12-N load (undertensioned), (4) LTT with a 24-N load (physiologically tensioned according to the cross-sectional area ratio of the lower trapezius muscle), and (5) LTT with a 36-N load (overtensioned). Glenohumeral abduction angle and superior migration of the humeral head were measured using 3-dimensional motion tracking. Cumulative deltoid force was recorded in real time throughout dynamic abduction motion by load cells connected to actuators.

RESULTS

Physiologically tensioned (Δ13.1°), undertensioned (Δ7.3°), and overtensioned (Δ9.9°) LTT each significantly increased the glenohumeral abduction angle compared with the irreparable PSRCT (P < .001 for all). Physiologically tensioned LTT achieved a significantly greater glenohumeral abduction angle than undertensioned LTT (Δ5.9°; P < .001) or overtensioned LTT (Δ3.2°; P = .038). Superior migration of the humeral head was significantly decreased with LTT compared with the PSRCT, regardless of tensioning. Physiologically tensioned LTT resulted in significantly less superior migration of the humeral head compared with undertensioned LTT (Δ5.3 mm; P = .004). A significant decrease in cumulative deltoid force was only observed with physiologically tensioned LTT compared with the PSRCT (Δ-19.2 N; P = .044). However, compared with the native state, LTT did not completely restore glenohumeral kinematics, regardless of tensioning.

CONCLUSION

LTT was most effective in improving glenohumeral kinematics after an irreparable PSRCT when maintaining physiological tension on the lower trapezius muscle at time zero. However, LTT did not completely restore native glenohumeral kinematics, regardless of tensioning.

CLINICAL RELEVANCE

Tensioning during LTT for an irreparable PSRCT may be important to sufficiently improve glenohumeral kinematics and may be an intraoperatively modifiable key variable to ensure postoperative functional success.

Middle Trapezius Tendon Transfer for Augmentation of In Situ Superior Capsular Reconstruction-Reinforced Partial Rotator Cuff Repair: Short-term Outcomes of a Prospective Cohort Study

Background

Middle trapezius tendon (MTT) transfer has been described for dynamic reproduction of supraspinatus function. For management of irreparable rotator cuff (RC) tears, this procedure can be coupled with in situ (long head of the biceps tendon-based) superior capsular reconstruction (SCR) and partial RC repair.

Purpose

To investigate the functional outcomes of augmentation of in situ SCR-reinforced partial RC repair with MTT transfer for the management of irreparable posterosuperior RC tears.

Study Design

Cohort study; Level of evidence, 3.

Methods

Conducted between September 2014 and March 2022, this study included 24 patients with irreparable posterosuperior RC tears who were allocated into 2 groups: patients managed with 2-layer tendon construct (in situ SCR-reinforced partial RC repair) (group A; n = 15) and patients managed with 3-layer tendon construct (MTT transfer-augmented, in situ SCR-reinforced partial RC repair) (group B; n = 9). Outcome measures included 2-year postoperative pain, range of motion (ROM) in forward flexion and external rotation, and the American Shoulder and Elbow Surgeons (ASES) and the shortened version of the Disabilities of the Arm, Shoulder and Hand (QuickDASH) scores. For data comparison, independent and paired t tests were used for parametric quantitative variables, and Mann-Whitney and Wilcoxon signed-rank tests were used for nonparametric quantitative variables; Fisher exact and McNemar tests were used for qualitative variables.

Results

The mean age of the patients was 58.40 ± 4.54 years in group A and 59.22 ± 4.46 years in group B; there were no between-group differences in baseline patient characteristics. Patients in both groups had significant preoperative to postoperative improvement on all outcome measures (P < .05 for all). Group B had a significantly higher magnitude of postoperative improvement compared with group A in forward flexion ROM (88.88° ± 29.34° vs 46.66° ± 20.93°; P = .001), external rotation ROM (32.22° ± 14.81° vs 16.0° ± 9.10°; P = .002), ASES score (71.07 ± 8.26 vs 57.87 ± 8.39; P = .001), and QuickDASH score (-70.20 ± 6.95 vs -58.34 ± 12.52; P = .007).

Conclusion

Augmentation of in situ SCR-reinforced partial RC repair with MTT transfer in a 3-layer tendon construct led to significantly greater improvement in postoperative ROM and functional scores compared with a 2-layer construct.

Rotator cuff irreparability or failure of repair (re-tear): technical note on middle trapezius tendon transfer for reproduction of supraspinatus function

Purpose

Based on its close anatomic features and nearly-collinear force vector to those of supraspinatus muscle, the current article describes a technique of middle trapezius tendon transfer for reproduction of supraspinatus function in the context of rotator cuff irreparability/re-tear management.

Methods

While seating the patient in beach-chair position, arthroscopic gleno-humeral examination and sub-acromial decompression are initially performed. Hamstring tendons are harvested and fashioned as flattened quadruple sheet. Through McKenzie approach, infraspinatus and subscapularis tendons are repaired. Then, medial half of middle trapezius insertion tendon is harvested from most medial 5-6 cm of the scapular spine. Through McKenzie approach, hamstring sheet is retrieved via a sub-trapezius/sub-acromial corridor from the scapular wound. Hamstring sheet is re-attached to cuff footprint by double row/suture bridge repair configuration. While retracting the scapula and placing gleno-humeral joint in 45^O-abduction/45^O-external rotation, hamstring sheet is re-attached to released middle trapezius tendon by non-absorbable sutures. Finally, tendon reconstruct is dynamically-tested in different positions of range of motion.

Results

Transfer of medial portion of middle trapezius insertion tendon (lengthened by interposition hamstring tendon sheet) to cuff footprint was technically feasible. Dynamic testing showed smooth sub-acromial gliding motion of the tendon reconstruct.

Conclusion

For reproduction of supraspinatus function, hamstring tendon augmented-middle trapezius tendon transfer to cuff footprint heralds a number of technical and biomechanical advantages; thus offering a potential effective modality of cuff irreparability/re-tear management in relatively young patients of high functional demands. However, current description should be investigated in further biomechanical and clinical studies to validate its long-term outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-021-00426-y.

Scapulothoracic Dyskinesis: A Concept Review

PURPOSE OF REVIEW

Scapulothoracic dyskinesis (SD) occurs when there is a noticeable disruption in typical position and motion of the scapula, which can result in debilitating pain. The purpose of this review is to describe the current knowledge regarding the diagnosis and management of scapulothoracic dyskinesis by providing an evidence-based overview of clinical exams and treatment modalities available for orthopedic surgeons and provide insight into which treatment modalities require further investigation.

RECENT FINDINGS

SD is highly prevalent in athletes, particularly those participating in overhead activities (e.g., baseball, tennis, and swimming) and can coexist with several shoulder pathologies. A holistic approach in the diagnosis of SD has been supported in the literature; however, it is important to recognize that diagnosis is currently limited to the absence of a quantitative SD clinical assessment. The main goal of the treatment of SD is to regain proper scapular positioning and dynamics. The standard of care for the management of SD is conservative interventions aimed at optimizing scapular kinematics. Surgical intervention is only considered in the presence of concomitant pathology requiring surgery. Due to the complexity of coordinated movement of the shoulder girdle, recent literature has begun to move away from the use of traditional orthopedic tests, in favor of a more system-based approach for the diagnosis of SD. We present a concise review of clinical exams and treatment modalities available for orthopedic surgeons in the management of SD.

The lower trapezius transfer: a systematic review of biomechanical data, techniques, and clinical outcomes

BACKGROUND

Lower trapezius (LT) transfers were originally described to restore external rotation (ER) in the management of brachial plexus palsy; however, there is recent interest in the role of this transfer to restore shoulder function, specifically ER, in patients with a massive irreparable rotator cuff tear (RCT). The purpose of this systematic review is to summarize the current literature pertaining to LT transfers, including biomechanics, techniques, and clinical outcomes for patients with brachial plexus palsy and massive RCTs.

METHODS

MEDLINE, EMBASE, and PubMed were searched for biomechanical and clinical studies, as well as technique articles. Four biomechanical studies reported on moment arms, range of motion (ROM), and force vectors. Seven clinical studies reported postoperative ROM and functional outcomes, and weighted mean improvements in ROM were calculated.

RESULTS

Overall, 18 studies were included, and then subdivided into 3 themes: biomechanical, technique, and clinical. Biomechanical studies comparing LT and latissimus dorsi (LD) transfers observed an overall larger moment arm in abduction and ER in adduction for the LT transfer, with similar results in forward elevation. Clinical studies noted significant improvement in shoulder function following the LT transfer, including ROM and functional outcome scores. There were several described techniques for performing the LT transfer, including arthroscopically assisted and open approaches, and the use of both allograft and autograft augmentation.

CONCLUSION

This study suggests that the LT transfer is generally safe, and the clinical and biomechanical data to date support the use of the LT transfer for restoration of function in these challenging patient populations.

Scapular and Shoulder Girdle Muscular Anatomy: Its Role in Periscapular Tendon Transfers

The importance of coordinated, normal scapulothoracic motion in facilitating full, pain-free motion of the shoulder complex has been increasingly studied over the past decade, leading to renewed interest in scapular-based reconstructions to improve shoulder girdle motion through the use of muscle advancements and tendon transfers. This article will review recent advances regarding scapulothoracic motion and the muscular stabilizers of the scapula, focusing on clinical diagnosis and anatomy as it pertains to scapular dyskinesis and common periscapular tendon transfers. Although many of these treatment techniques remain in their infancy and further follow-up is necessary before universal adoption, they provide a novel means of addressing difficult-to-treat and complex shoulder girdle pathologies.