Editorial Commentary: Superior Capsular Reconstructions in Cases of Irreparable Rotator Cuff Tendons Only Partially Restore Anatomy, Yet Significantly Normalize Biomechanics-Without Resorting to Reverse Anatomy.

The goal of shoulder superior capsular reconstruction and/or anterior cable reconstructions, at least in terms of biomechanics, is to primarily restore a fulcrum to assist with pain control and functional optimization, with the secondary hope of maintaining cartilage. Fully restoring glenohumeral joint loads with SCR cannot be expected in the setting of persistent tendon insufficiency. Biomechanical studies characterizing shoulder capsular reconstructions have demonstrated anatomic and functional restorations toward normalization when tested with standard biomechanical methods.

Anterior Cable Reconstruction: Prioritize Rotator Cable and Tendon Cord When Considering Superior Capsular Reconstruction.

Although distinct in name, the anterior cable of the superior capsule and tendon cord of the supraspinatus are structurally one in the same at the attachment on the greater tuberosity footprint. Force transmission through both structures where they converge and interdigitate at this location is disproportionately high, which has implications on functional impact. Superior capsule reconstruction, and, specifically, the anterior cable of the superior capsule, has been shown to assist in maintaining superior stability and a functional fulcrum of the glenohumeral joint, without overconstraining range of motion.

Editorial Commentary: Anterior Cable Reconstruction for the Shoulder Superior Capsule: Time for "Indication Rounds".

Anterior cable reconstruction (ACR) techniques for the superior capsule are multiple and varied. To optimize patient outcomes, technical considerations must be supported by basic science, both anatomically and biomechanically. ACR was designed to treat only partially repairable rotator cuff tendon tears, to provide a static support to a dynamic partial (and therefore "nonanatomic") repair, and to treat tears that could not be treated by transosseous-equivalent footprint-restoring "anatomic" repairs (both capsule and tendon repaired), but were also not so large as to necessitate superior capsule reconstruction.

Biomechanical Assessment of a V-Shaped Semitendinosus Allograft Anterior Cable Reconstruction for Irreparable Rotator Cuff Tears.

Purpose: The purpose of this study was to biomechanically assess superior stability, subacromial contact pressures, and glenohumeral kinematics of a V-shaped anterior cable reconstruction with semitendinosus allograft (VST) in a massive rotator cuff tear (MCT) model.

Methods: Eight cadaveric shoulders (mean age, 66 years; range, 48 to 72 years) were tested with a custom testing system used to evaluate superior translation, subacromial contact pressure, and glenohumeral kinematics at 0°, 20°, and 40° glenohumeral abduction and 0°, 30°, 60°, and 90° of external rotation (ER). Conditions tested included (1) native state, (2) MCT (complete supraspinatus and ½ infraspinatus), a (3) VST.

Biomechanical analysis of progressive rotator cuff tendon tears on superior stability of the shoulder.

Background: The biomechanical relationship between irreparable rotator cuff tear size and glenohumeral joint stability in the setting of superiorly directed forces has not been characterized. The purpose of this study was to quantify kinematic alterations of the glenohumeral joint in response to superiorly directed forces in a progressive posterosuperior rotator cuff tear model.

Methods: Nine fresh-frozen cadaveric shoulders (mean age; 58 years) were tested with a custom shoulder testing system.

Anterior Cable Reconstruction Using the Proximal Biceps Tendon for Large Rotator Cuff Defects.

Tears of the rotator cuff tendons can occur that do not allow anatomic footprint restoration yet may not be large enough to require a superior capsular reconstruction technique. Typically, these intermediate-sized tears are addressed with a medialized repair or partial repair technique. A partially repaired rotator cuff tendon, however, can lead to a high retear rate, as the repaired tendon is required to serve as both a dynamic tendon and a static ligamentous stabilizer.

Anterior Cable Reconstruction of the Superior Capsule Using Semitendinosus Allograft for Large Rotator Cuff Defects Limits Superior Migration and Subacromial Contact Without Inhibiting Range of Motion: A Biomechanical Analysis.

Purpose: To biomechanically assess translation, contact pressures, and range of motion for anterior cable reconstruction (ACR) using hamstring allograft for large to massive rotator cuff tears.

Methods: Eight cadaveric shoulders (mean age, 68 years) were tested with a custom testing system. Range of motion (ROM), superior translation of the humeral head, and subacromial contact pressure were measured at 0°, 30°, 60°, and 90° of external rotation (ER) with 0°, 20°, and 40° of glenohumeral abduction.

Anterior Cable Reconstruction Using the Proximal Biceps Tendon for Large Rotator Cuff Defects Limits Superior Migration and Subacromial Contact Without Inhibiting Range of Motion: A Biomechanical Analysis.

Purpose: To assess an anterior cable reconstruction (ACR) using autologous proximal biceps tendon for large to massive rotator cuff tears.

Methods: Nine cadaveric shoulders (mean age, 58 years) were tested with a custom testing system. Range of motion, superior translation of the humeral head, and subacromial contact pressure were measured at 0°, 30°, 60°, and 90° of external rotation (ER) with 0°, 20°, and 40° of glenohumeral abduction.

Knotless Transosseous-Equivalent Rotator Cuff Repair Improves Biomechanical Self-reinforcement Without Diminishing Footprint Contact Compared With Medial Knotted Repair.

Purpose: To assess the effect of medial-row knots on self-reinforcement and footprint contact characteristics for transosseous-equivalent repair compared with the same construct without knots.

Methods: In 8 fresh-frozen human shoulders, transosseous-equivalent repairs with and without medial-row mattress knots were performed in each specimen. A pressure sensor was fixed at the tendon-footprint interface for all repairs.

Editorial Commentary: Can Passive Muscle Stiffness in a Cadaveric Study Be Clinically Related to Using Knotted Versus Knotless Rotator Cuff Repair?

Is a biomechanical cadaveric study to assess the effect of rotator cuff tear size and repair technique on supraspinatus muscle stiffness clinically relevant? A study in this issue compared double-row and knotless transosseous-equivalent repairs, but notably, muscle loading was not simulated. Results showed that the knotless transosseous-equivalent repair for larger tears demonstrated a more uniform stiffness distribution across the supraspinatus muscle compared with the double-row repair. However, given the inherently asymmetrical functional anatomy and morphology of the supraspinatus tendon-muscle unit, when muscle tone exists, the effect of the repair technique on muscle stiffness in vivo may not be determined based on the findings of this study.

Does transosseous-equivalent rotator cuff repair biomechanically provide a "self-reinforcement" effect compared with single-row repair?

Background: Transosseous-equivalent (TOE) rotator cuff repair has been theorized to be "self-reinforcing" against potentially destructive and increasing tendon loads. The goal of this study was to biomechanically verify and characterize the effect of increasing tendon load on frictional resistance over a repaired footprint for single-row (SR) and TOE repair techniques.

Methods: In 10 fresh frozen human shoulders, TOE and SR supraspinatus tendon repairs were performed in each specimen.

Biomechanical effects of a 2 suture-pass medial inter-implant mattress on transosseous-equivalent rotator cuff repair and considerations for a "technical efficiency ratio".

Background: Rotator cuff repair involving fewer tendon suture passes without compromising biomechanical performance would represent a technical advancement. An inter-implant "medial pulley-mattress" transosseous-equivalent (MP-TOE) repair requiring fewer tendon suture-passes was hypothesized to provide equivalent biomechanical characteristics compared to the control.

Methods: In 6 human cadaveric shoulders, a transosseous-equivalent (TOE) repair (control) was performed utilizing 2 separate medial mattresses resulting in 4 tendon-bridging sutures.

Rotator cuff tendon repair morphology comparing 2 single-anchor repair techniques.

Purpose: To compare the effect of 2 common rotator cuff repair techniques, for smaller tears limited to the use of a single anchor, on tendon morphology in relation to the footprint.

Methods: Six matched pairs of human shoulders were dissected, and a standardized 10-mm supraspinatus tendon tear was created. Two single-anchor repairs were performed: simple repair with the anchor on the footprint or inverted-mattress repair with the anchor 1 cm distal-lateral to the footprint.

Biomechanical validation of rotator cuff repair techniques and considerations for a "technical efficiency ratio".

Biomechanical studies are commonly used to validate new or modified rotator cuff repair techniques. Additional knots, more tendon suture passes, and obligatory suture management requirements are often the "cost" for improved biomechanical results. This cost can amount to increased technical difficulty and surgical times.

Revision ulnar collateral ligament reconstruction using a suspension button fixation technique.

Background: Revision ulnar collateral ligament reconstruction remains a challenging problem. The objective of this study was to biomechanically evaluate an ulnar collateral ligament reconstruction technique using a suspension button fixation technique that can be used even in the case of ulnar cortical bone loss.

Hypothesis: An ulnar suspension fixation technique for ulnar collateral ligament reconstruction can restore elbow kinematics and demonstrate failure strength comparable to that of currently available techniques.

Biomechanical analysis of a knotless transtendon interimplant mattress repair for partial-thickness articular-sided rotator cuff tears.

Background: A transtendon interimplant mattress repair along the medial row for partial-thickness rotator cuff repairs has been described with clinical success. However, the biomechanical characteristics for such a repair have not been elucidated.

Hypothesis: A knotless interimplant mattress repair may show improved or equivalent load and strain characteristics, compared with a repair using isolated mattress repairs over each of 2 anchors.

Influence of distinct anatomic subregions of the supraspinatus on humeral rotation.

The supraspinatus, having distinct anterior and posterior subregions, is most commonly considered an abductor of the humerus, but it has also been shown to induce humeral rotation. The objective of this study was to quantify the magnitude and direction of humeral rotation that results from loading the distinct anterior and posterior subregions of the supraspinatus. Fourteen cadaver specimens were tested under four loading conditions based on physiological cross section area of the supraspinatus: (1) anterior only; (2) posterior only; (3) physiologic (each subregion loaded simultaneously); and (4) nonphysiologic (the tendon loaded as a whole).

The effect of abduction and rotation on footprint contact for single-row, double-row, and modified double-row rotator cuff repair techniques.

Background: An abduction pillow and abduction and rotation exercises are commonly used after rotator cuff repair. The effect of glenohumeral abduction and rotation on footprint contact has not been elucidated.

Hypothesis: Abduction will decrease tendon-to-bone contact for all repairs.

Treating full-thickness cuff tears in the athlete: advances in arthroscopic techniques.

Full-thickness rotator cuff tears in the athlete generally occur from either high-energy contact or repetitive overhead activity. Surgical management of these injuries with a technique that maximizes footprint contact while providing a gap-resistant repair may enhance an optimal healing environment. The elite overhead athlete with a full-thickness tear has a relatively poor prognosis, and requires special consideration.

The effect of dynamic external rotation comparing 2 footprint-restoring rotator cuff repair techniques.

Background: Allowing for humeral external rotation while loading rotator cuff repairs has been shown to affect tendon biomechanics when compared with testing with the humerus fixed. Adding dynamic external rotation to a tendon-loading model using footprint-restoring repairs may improve our understanding of rotator cuff repair response to a common postoperative motion.

Hypothesis: A tendon suture-bridging repair will demonstrate better load sharing compared to a double-row repair, and there will be a differential gap formation between the anterior and posterior tendon regions.

The biomechanical effects of dynamic external rotation on rotator cuff repair compared to testing with the humerus fixed.

Background: Biomechanical testing without humeral motion is a standard method for evaluating rotator cuff repair constructs. This cannot elucidate the effects of dynamic external rotation on the repair, which is a common postoperative motion.

Hypothesis: Biomechanical properties and gap formation of rotator cuff repairs will be different when dynamic external rotation is allowed to occur during loading.