Arthroscopic suture anchor capsulorrhaphy versus labral-based suture capsulorrhaphy in a cadaveric model

Biomechanical Studies for Glenoid Based Labral Repairs With Suture Anchors Do Not Use Consistent Testing Methods: A Critical Systematic Review

PURPOSE

The purpose of this systematic review was to investigate variability in biomechanical testing protocols for laboratory-based studies using suture anchors for glenohumeral shoulder instability and SLAP lesion repair.

METHODS

A systematic review of Medline, Embase, Scopus, and Google Scholar using Covidence software was performed for all biomechanical studies investigating labral-based suture anchor repair for shoulder instability and SLAP lesions. Clinical studies, technical notes or surgical technique descriptions, or studies treating glenoid bone loss or capsulorrhaphy were excluded. Risk of bias (ROB) was assessed with the ROBINS-I tool. Study quality was assessed with the Quality Appraisal for Cadaveric Studies. Heterogeneity was assessed with the I² statistic.

RESULTS

A total of 41 studies were included. ROB was serious and critical in 27 studies, moderate in 13, and low in 1; 6 studies had high quality, 21 good quality, 10 moderate quality, 2 low quality, and 2 very low quality. Thirty-one studies used and 22 studies included cyclic loading. Angle of anchor insertion was reported by 33 studies. The force vector for displacement varied. The most common directions were perpendicular to the glenoid (n = 9), and anteroinferior or anterior (n = 8). The most common outcome measures were load to failure (n = 35), failure mode (n = 23), and stiffness (n = 21). Other outcome measures included load at displacement, displacement at failure, tensile load at displacement, translation, energy absorbed, cycles to failure, contact pressure, and elongation.

CONCLUSION

This systematic review demonstrated a clear lack of consistency in those cadaver studies that investigated biomechanical properties after surgical repair with suture anchors for shoulder instability and SLAP lesions. Testing methods between studies varied substantially with no universally applied standard for preloading, load to failure and cyclic loading protocols, insertion angles of suture anchors, or direction of loading. To allow comparability between studies standardization of testing protocols is strongly recommended.

Biomechanical effects of anterior capsular plication and rotator interval closure in simulated anterior shoulder instability

PURPOSE

The purpose of this study was to determine the effect of a stepwise arthroscopic anterior plication and arthroscopic-equivalent rotator interval (RI) closure on glenohumeral range of motion, kinematics, and translation in the setting of anterior instability.

METHODS

Six cadaveric shoulders were stretched to 10 % beyond maximum external rotation (ER) to create an anterior shoulder instability model. Range of motion, kinematics, and glenohumeral translations were recorded for the following conditions: (1) intact, (2) stretched, (3) after anterior capsular plication, and (4) after RI closure.

RESULTS

The total range of motion after capsular stretching increased significantly in the 60° abduction position (p = 0.037). Average ER and total rotation were significantly decreased from the intact and stretched conditions by both repair conditions at 60° and 0° of glenohumeral abduction (p < 0.05), with no significant difference between plication and additional RI closure. At 0° abduction and 0° ER, glenohumeral translation decreased significantly from the stretched condition after RI closure with 10 and 15 N anterior and 10 N posterior loads (p < 0.05). At 30° ER, translation after RI closure was significantly less than both the intact and stretched conditions with 10 N anterior loads (p = 0.009; p = 0.004). These changes in translational stability were not seen with plication alone.

CONCLUSIONS

Anterior capsular plication reduced glenohumeral range of motion back to the intact state, and often tighter. RI closure did not contribute significantly to the reduction in the range of motion, but had implications regarding glenohumeral translation. Caution should be taken when performing anterior plication and combined repairs to avoid overtightening. Intraoperative translations could be useful when debating RI closure in patients with unidirectional anterior glenohumeral instability.

The thrower's shoulder

Throwers, or athletes who engage in repetitive overhead motions, are a unique subset of athletes that experience distinct shoulder injuries. Athletes engaged in baseball comprise the majority of patients seeking orthopedic care for throwing related injuries. Injuries specific to throwers most commonly involve the labrum and the undersurface of the rotator cuff. In addition, tissue changes in both the anterior and posterior glenohumeral capsule are common with repetitive overhead motions. These capsular changes alter. This article will examine the pathomechanics of injuries to throwers, elaborate means of diagnoses of cuff and labral injury and discuss recent advances in both non-operative and operative interventions, including preventative principles.