Editorial Commentary: Precise Repair of Partial Subscapularis Tendon Tears Is Essential

Analysis of Rotator Cuff Muscle Injury on the Drawing Side of the Recurve Bow: A Finite Element Method

Background

This study establishes the shoulder model on the drawing side of recurve archers by the finite element method and finds out the stress changes on the rotator cuff muscles in the position of the humerus and scapula under different stages of special techniques. The aim of this study is to investigate the mechanism of rotator cuff damage on a recurve archer's drawing arm.

Methods

A 22-year-old healthy male's shoulder CT and MRI data were collected, and the drawing side shoulder joint finite element model was constructed, which contains the structure of the shoulder blades, clavicle, humerus, supraspinatus, infraspinatus, teres minor, and subscapularis. The humerus on the drawing arm was simulated to raising the bow, drawing, holding, and releasing on the scapula plane, and stress changes in rotator cuff muscles are analyzed.

Results

The peak stress on the infraspinatus increased slowly, and from the start of raising the bow to hold and release, the stress peak increased from 0.007 MPa to 0.009 MPa. The peak stress on teres minor rises slowly from 0.003 MPa at the start of raising the bow to 0.010 MPa at the moment of releasing. The peak stress in the subscapularis increased from 0.096 MPa to 0.163 MPa between the start of raising the bow and releasing. The peak stress on the supraspinatus varied greatly, and from the start of raising the bow to the start of drawing, the stress peak increased markedly from 1.159 MPa to 1.395 MPa. Subsequently, the stress peak immediately decreased to 1.257 MPa at the start of holding and then increased to 1.532 MPa at releasing.

Conclusion

The position of the humerus and scapula would change with the different stages of special techniques. It causes stress changes in the rotator cuff muscles, and when the stress accumulates over time, the shoulder 5on the drawing side will gradually become injured and dysfunctional. In combination with the depth of the structural site and the surrounding structural features, corrective exercises can be used to prevent injury to the rotator cuff muscles.

Limited Biomechanical Evidence Behind Single Row Versus Double Row Repair of Subscapularis Tears: A Systematic Review

Purpose

To systematically review the literature for studies investigating the biomechanical properties of constructs used to repair isolated subscapularis tears in time zero human cadaveric studies.

Methods

A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Three electronic databases were searched for studies that reported on the construct technique and biomechanical outcomes for the repair of isolated subscapularis tears in human cadaveric specimens. Ultimate load, gap formation, stiffness, and failure mode were documented. Methodological quality was assessed using the Quality Appraisal for Cadaveric Studies (QUACS) scale.

Results

Six articles qualified (104 shoulders [72 single-row, 26 double-row, 6 transosseous]; mean QUACS score 10.5 ± 1) and were analyzed. Studies varied in the number and type of anchors and construct technique (1-2 anchors single-row; 3-4 anchors double-row; bioabsorbable or titanium anchors) and suture(s) used (no. 2 FiberWire or FiberTape), subscapularis tear type (25%, 33%, 50%, or 100% tear), and whether a knotless or knotted fixation was used. In studies that created full-thickness, upper subscapularis tears (Fox-Romeo II/III or Lafosse II), no significant differences were seen in ultimate load, gap formation, and stiffness for knotted versus knotless single-row repair (2 studies) and single-row versus double-row repair (1 study). Double-row repair of complete subscapularis tears demonstrated higher ultimate load, stiffness, and lower gap formation in 1 study. Ultimate load differed between the studies and constructs (single-row: range, 244 N to 678 N; double-row: range 332 N to 508 N, transosseous: 453 N). Suture cutout was the most common mode of failure (59%).

Conclusion

Because of the limited number of studies and varying study designs in examining the biomechanical properties of repair constructs used for subscapularis tears, there is inconclusive evidence to determine which construct type is superior for repairing subscapularis tears.

Clinical Relevance

Results from biomechanical studies of clinically relevant subscapularis repair constructs are important to guide decision-making for choosing the optimal construct for patients with subscapularis tears.