Shoulder Positioning during Superior Capsular Reconstruction: Computational Analysis of Graft Integrity and Shoulder Stability

The shoulder position during fixation of the graft may be a key factor impacting the outcome of arthroscopic superior capsular reconstruction (ASCR) in irreparable rotator cuff tears (IRCTs). However, biomechanical evidence regarding this effect is lacking. The aim of this study was to evaluate the influence of the shoulder position during fixation of the graft on shoulder stability and graft tear risk in ASCR. A 3-D musculoskeletal model of the upper limb was modified to account for the fixation of the graft in ASCR, assuming a full-thickness tear of the supraspinatus tendon. The concomitant tenotomy of the long head of the biceps (LHB) tendon was also studied. The biomechanical parameters evaluated included the strain of the graft and the glenohumeral joint reaction force (GH JRF), which were used to evaluate graft integrity and shoulder stability, respectively. Fixation of the graft considering abduction angles greater than 15° resulted in a high risk for graft tearing when the arm was adducted to the side of the trunk. For abduction angles below 15°, the mean shoulder stability improved significantly, ranging between 6% and 20% (p < 0.001), compared with that in the preoperative condition. The concomitant tenotomy of the LHB tendon resulted in loss of stability when compared to ASCR with an intact LHB tendon. The position of the shoulder during fixation of the graft has a significant effect on shoulder stability and graft tear risk after ASCR in IRCTs. This study provides new and important information regarding the role of shoulder positioning during fixation of the graft.

Impact of shoulder, elbow and forearm position on biceps tendon excursion: A cadaveric study

Purpose: This experimental study investigated the long head biceps tendon (LHBT) excursion that occurs at various positions of the upper limb during tendon stabilizing procedures. We hypothesized that shoulder abduction, elbow extension and forearm pronation would maximize the excursion of the LHBT and potential impacts on tendon stabilization. Materials & Methods: Forequarter specimens from 12 fresh frozen cadavers were used in this study. The study was performed at 0° and 30° of shoulder abduction. Elbow position was either 90° of flexion or full extension with the forearm either in full pronation or supination. A total of 14 combinations of positions were studied. A load of 55 N was applied to the distal biceps. The excursion of the proximal part of LHBT was measured for each of the different positions. Results: At a shoulder position of 30° of flexion, shoulder abduction of 30° created significantly greater excursion than 0° of shoulder abduction ( p < 0.001). Both full extension of the elbow and full pronation of the forearm also showed significant excursion of the tendon when compared to supination ( p < 0.001). Conclusions: The position of the shoulder, elbow and forearm has a significant effect on biceps excursion. Thirty degrees of shoulder abduction and 30° of forward flexion with the elbow in full extension and the forearm in full pronation maximizes excursion. Clinical Relevance: Information about the excursion of the LHBT affected by the position of the upper limb is useful for any biceps tendon stabilizing procedure. During an operation, the position of the upper limb should be monitored in order to maintain a proper anatomic length-tension relationship.

Analysis of Preoperative and Operative Factors Influencing Postoperative Shoulder Imbalance in Lenke Type 1 Adolescent Idiopathic Scoliosis

Background Postoperative shoulder imbalance is a common complication in adolescent idiopathic scoliosis and may impair patient satisfaction. The little data in the literature on the prediction and treatment of postoperative shoulder imbalance is incongruous. According to some studies, postoperative shoulder imbalance depends on the superior instrumented vertebral bodies, skeletal maturity, extent of correction and flexibility of the major curve. Question Can preoperative radiological parameters from X-ray and traction films as well as correction of the curves be used to identify a factor impacting on postoperative shoulder imbalance? Material and Methods Prospective data in adolescent idiopathic scoliosis with thoracic curve (Lenke type 1), operated on between 2015 and 2018 at a scoliosis centre, were analysed retrospectively based on full-length X-rays of the spine (pre-/postOP and follow-up (FU)) and preoperative-traction films: age; correction of proximal, main and lumbar curve; shoulder height [mm]; clavicle angle [°]; T1 tilt [°]; coronal plumb line deviation [mm]. The findings were expressed as means with standard deviation. Changes in parameters over time (postOP-FU) were compared by t test (significance level α = 0.05). The correlation between preOP parameters and extent of correction with postoperative shoulder imbalance (≥ 15 mm) was determined by Pearson correlation and regression classification analysis. Outcomes 55 patients with adolescent idiopathic scoliosis, mean age of 15 ± 1.4 years. The FU-rate after a mean of 15 months was 80% (n = 44). Correction of proximal, main and lumbar curve: 47.0%, 75.8% and 68.8%, respectively, without statistically significant change (Δ) in FU (p > 0.05). Shoulder height was − 11.0 ± 12.7 mm (preOP), 15.5 ± 13.4 mm (postOP), 10.1 ± 10.6 mm (FU) (p < 0.05). 38% of those with adolescent idiopathic scoliosis had preOP right shoulder elevation; 55% (postOP) and 32% (FU) respectively had postoperative shoulder imbalance (left shoulder elevation). Strong statistical correlation was found for Δshoulder position (FU-preOP) with pre-OP shoulder position (r = − 0.7), and Δshoulder position (pre-OP traction films) (r = 0.5) with pre-OP clavicle angle (r = − 0.5). On regression classification analysis, 81.8% of cases did display postoperative shoulder imbalance if proximal curve correction was ≤ 64.4%; main and lumbar curve correction, Δshoulder elevation (preOP traction films) played a secondary role. Discussion One common complication even in Lenke type 1 adolescent idiopathic scoliosis is postoperative shoulder imbalance. Preoperative planning should include traction films, preoperative shoulder position and clavicle angle to avoid postoperative shoulder imbalance. Moderate correction of proximal curve is critical for postoperative shoulder balance.

Usability, functionality, and efficacy of a custom myoelectric elbow-wrist-hand orthosis to assist elbow function in individuals with stroke

Introduction After stroke, upper limb impairment affects independent performance of activities of daily living. We evaluated the usability, functionality, and efficacy of a myoelectric elbow-wrist-hand orthosis to provide support, limit unsafe motion, and enhance the functional motion of paralyzed or weak upper limbs. Methods Individuals with stroke participated in a single-session study to evaluate the device. Ability to activate the device was tested in supported and unsupported shoulder position, as well as the elbow range of motion, ability to maintain elbow position, and ability to lift and hold a range of weights while using the device. Results No adverse events were reported. 71% of users were able to operate the device in all three active myoelectric activation modes (Biceps, Triceps, Dual) during testing. Users were able to hold a range of wrist weights (0.5–2 lbs) for 10–120 seconds, with the largest percentage of participants able to hold weights with the device in Biceps Mode. Conclusions The myoelectric elbow-wrist-hand orthosis improved range of motion during use and was efficacious at remediating upper extremity impairment after stroke. All users could operate the device in at least one mode, and most could lift and hold weights representative of some everyday objects using the device.