Three-dimensional kinematic features in large and massive rotator cuff tears with pseudoparesis.

BACKGROUND: Although massive rotator cuff tears occasionally lead to severe impairment of shoulder function, the criteria for losing the ability to elevate the arm are unclear. This study aimed to analyze the features of both tear size and 3-dimensional (3D) shoulder kinematics that correspond to the loss of the ability to elevate the arm in patients with large and massive rotator cuff tears. METHODS: We prospectively enrolled patients with rotator cuff tears, including the supraspinatus and more than half of the subscapularis or more than two-thirds of the infraspinatus, without severe pain. A total of 13 patients (15 shoulders) were divided into 2 groups: 9 shoulders in the pseudoparesis (P) group and 6 shoulders in the non-pseudoparesis (NP) group. Fluoroscopic images were collected during active scapular-plane elevation, and 3D shoulder kinematics was analyzed using 2-dimensional-3D registration techniques. The radiographic findings and 3D kinematic results were compared between the groups. The correlation between tear size and 3D kinematics was also investigated. RESULTS: The most superior position of the humeral head center was significantly higher in the P group (6.7 ± 3.0 mm in P group vs. 3.6 ± 1.3 mm in NP group, P = .0321). Superior migration, which was defined as the most superior position > 5 mm, was significantly more frequent in the P group (7 shoulders and 1 shoulder in the P and NP groups, respectively; P = .0201). Thoracohumeral external rotation was significantly smaller in the P group (16° ± 31° in P group vs. 91° ± 21° in NP group, P < .0001). The total tear size and the tear sizes of the anterior and posterior rotator cuffs were significantly correlated with the superior (r = 0.68, P = .0056), anterior (r = 0.68, P = .0058), and posterior (r = -0.80, P = .0004) positions of the humeral head center. The tear size of the posterior rotator cuff also tended to be correlated with glenohumeral external rotation (r = -0.48, P = .0719). CONCLUSION: Anterior and posterior rotator cuff tears cause significant superior and anteroposterior translations of the humeral head, and posterior cuff tears may lead to loss of glenohumeral external rotation. With these abnormal kinematics, superior migration and loss of thoracohumeral external rotation were identified as features of pseudoparesis.

Gleno-humeral abduction measurement in patients with Ehlers-Danlos syndrome.

BACKGROUND: No genetic tests or other investigations are available to establish the definitive diagnosis of Ehlers-Danlos syndrome (EDS). A presumptive diagnosis can be made based on a converging set of findings, including a family history of the disease, the patient's medical history, and the physical findings. The Beighton score is currently the reference standard tool for assessing joint hypermobility, which must be present in at least 5 of 9 tested joints. However, joint hypermobility testing may be challenging, for instance in patients with pain during mobilisation and/or tight hamstring muscles. Furthermore, the Beighton score may be less than 5 in patients with other unequivocal evidence of EDS. The objective of this study was to assess the contribution of gleno-humeral abduction measurement to the diagnosis of EDS. HYPOTHESIS: Gleno-humeral abduction measurement using a standardised method assists in the diagnosis of EDS. METHODS AND MATERIAL: Retrospective case-control study comparing 110 patients with known EDS (cases) to 100 controls. RESULTS: Gleno-humeral abduction was significantly greater in the cases than in the controls, irrespective of age, sex, and Beighton score. Gleno-humeral abduction beyond 90° was 92.5% sensitive and 96.4% specific. Inter-examiner reproducibility of gleno-humeral abduction measurement was excellent. DISCUSSION: Increased gleno-humeral abduction may be sufficient to demonstrate joint hypermobility and to suggest EDS in patients whose personal and family history is consistent with this diagnosis. LEVEL OF EVIDENCE: III, case-control study.