The effect of humeral tray thickness on glenohumeral loads in a reverse shoulder 'smart' implant.

PURPOSE: The aim of this study was to observe the effects of changing humeral tray thickness on the resultant of intraoperative glenohumeral joint loads using a load-sensing system (LSS). METHODS: An rTSA was performed on fresh frozen full-body cadaver shoulders by using an internal proprietary LSS on the humeral side. The glenohumeral loads (Newtons) and the direction of the resultant force applied on the implant were recorded during four standard positions (External rotation, Extension, Abduction, Flexion) and three "complex" positions of Activity Daily Life ("behind back", "overhead reach" and "across chest"). For each position, the thickness was increased from 0 to 6 mm in a continuous fashion using the adjustment feature of the humeral system. Each manoeuvre was repeated three times. RESULTS: All shoulder positions showed a high repeatability of the glenohumeral load magnitude measured with an intra-class correlation coefficient of over 0.9. For each position, we observed a strong but no linear correlation between humeral tray thickness and joint loads. It was a cubical correlation (rs = 0,91) with a short ascending phase, then a plateau phase, and finally a phase with an exponential growth of the loads on the humeral implant. In addition, an increase in trail-poly thickness led to a recentering of force application at the interface of the two glenohumeral implants. CONCLUSION: This study provides further insight into the effects of humeral implant thickness on rTSA glenohumeral joint loads during different positions of the arm. Data obtained using this type of device could guide surgeons in finding the proper implant balance during rTSA.

The Association of Age and Sex With Joint Angles and Coordination During Unanticipated Cutting in Soccer Players.

Deficits in movement patterns during cutting while running might place soccer players at risk of injury. The objective was to compare joint angles and intersegment coordination between sexes and ages during an unanticipated side-step cutting task in soccer players. This cross-sectional study recruited 11 male (four adolescents and seven adults) and 10 female (six adolescents and four adults) soccer players. Three-dimensional motion capture was used to measure lower-extremity joint and segment angles as participants performed an unanticipated cutting task. Hierarchical linear models examined relationships between joint angle characteristics with age and sex. Continuous relative phase was used to quantify intersegment coordination amplitude and variability. These values were compared between age and sex groups using analysis of covariance. Adult males had greater hip flexion angle excursions than adolescent males, while adult females had smaller excursions than adolescent females (p = .011). Females had smaller changes in hip flexion angles (p = .045), greater hip adduction angles (p = .043), and greater ankle eversion angles (p = .009) than males. Adolescents had greater hip internal rotation (p = .044) and knee flexion (p = .033) angles than adults, but smaller changes in knee flexion angles at precontact compared with stance/foot off (p < .001). For intersegment coordination, females were more out-of-phase than males in the foot/shank segment in the sagittal plane. There were no differences in intersegment coordination variability between groups. Differences in joint motion during an unanticipated cutting task were present between age groups and sexes. Injury prevention programs or training programs may be able target specific deficits to lower injury risk and improve performance.

Arthroscopic management of intra- and juxta-articular osteoid osteoma of the upper extremity: a systematic review of the literature.

BACKGROUND: Intra- and juxta-articular osteoid osteoma (OO) is rare and can result in irreversible joint damage. Recently, arthroscopic surgery is being used more and more to avoid complications associated with other treatment modalities. METHODS: On October 13, 2019, we conducted a systematic review of the literature available in PubMed and EMBASE regarding the arthroscopic management of OO involving the joints of the upper extremity. Predetermined inclusion criteria were used to include any relevant article published on and before that date for further analysis. Treatment success rate and tumor recurrence rate were considered the primary outcomes in our analysis. RESULTS: Out of 113 studies, 19 met our inclusion criteria. Of the 32 reported cases in these 19 articles, ten involved the shoulder joint, 19 involved the elbow joint and three involved the wrist joint. Overall treatment success rate was 93.8%. Tumor recurrence rate was 0.0%. No postoperative complications (0.0%) were reported among cases involving the shoulder joint. Two out of 24 (8.3%) patients with elbow OO failed arthroscopic treatment due to incomplete excision, and two (4%) experienced minor complications. Among the three cases of wrist OO, two (66.7%) patients had residual postoperative pain and decreased hand grip strength. CONCLUSION: Arthroscopic management of OO of the upper extremity joints is highly successful and results in no tumor recurrence; however, there is a risk of incomplete resection in areas more difficult to access by arthroscopy.

Latissimus dorsi tendon transfer for massive irreparable cuff tears: an anatomic study.

The purpose of this study was to describe landmarks for latissimus dorsi tendon transfer in massive irreparable tears of the rotator cuff. Nine pairs of embalmed cadaveric shoulders were dissected. Crucial structures were identified, and their relationship with various bony and soft-tissue reference points was documented. Identification of the dense fibrous band, at the confluence of the teres major and latissimus dorsi musculotendinous unit, facilitates localization of the radial nerve, which crosses deep to this landmark. The axillary nerve can be seen to exit the quadrangular space 27 mm medial to the latissimus dorsi insertion into the proximal humerus, whereas the thoracodorsal neurovascular pedicle inserts into the latissimus dorsi 110 mm from the humeral tendon's humeral attachment. Harvest of the latissimus dorsi tendon can be safely accomplished by identifying the dense fibrous band and releasing the tendon within 2 cm of its humeral attachment.

Comparison of the stability of various internal fixators used in the treatment of osteochondritis dissecans--a mechanical model.

The purpose of this study was to determine what characteristics of fixation devices used in the treatment of osteochondritis dissecans (OCD) contribute to improved stability to resist shear loading. An OCD model was designed using rigid polyurethane foam. Each specimen consisted of two components, an osteochondral fragment and a corresponding defect. A total of 40 specimens were prepared and assigned to one of four groups: control (no extrinsic stabilizer); two 2-mm-diameter Kirschner wires (K-wires), 40 mm in length; one threaded washer and a 28-mm screw; and one threaded washer and a 38 mm screw. Each specimen was mounted onto an Iosipescu shear test fixture and subjected to shear loads at a pseudo-static displacement rate of 0.075 mm/s. All groups demonstrated some stability; controls were significantly less stable than all other groups. The group with the threaded washer and 38-mm screw demonstrated the greatest stability (p < 0.001), and no difference was noted between the K-wire and 28-mm screw groups. These results suggest that, in this OCD model, friction conferred some intrinsic stability to resist loads in shear. However, stability was improved with the use of long implants that compressed the fragments together.