Analysis of in vivo humeral rotation of reverse total shoulder arthroplasty patients during shoulder abduction on the scapular plane with a load.

BACKGROUND: Few studies have investigated the kinematics after reverse total shoulder arthroplasty (RTSA). This study aimed to compare the shoulder kinematics in RTSA patients during shoulder abduction on the scapular plane with and without a load and yield information regarding the function of stabilizing the joints against gravity for the functional assessment of the shoulder after RTSA, which could lead to changes in postoperative rehabilitation treatment. METHODS: Twenty RTSA patients (7 men, 13 women; mean age: 78.1 [64-90] years) were examined. First, active shoulder abduction in the scapular plane was captured using single-plane fluoroscopic X-ray images. Imaging was performed by stipulating that one shoulder abduction cycle should be completed in 6 s. Two trials were conducted: one under a load equivalent to 2% of body weight and one without a load. Next, a three-dimensional (3D) model of each humeral and scapular component was matched to the silhouette of the fluoroscopic image to estimate the 3D dynamics. By using the 3D dynamic model obtained, the kinematics of the glenosphere and humeral implant were calculated relative to the shoulder abduction angle on the scapular plane and were compared between groups with and without a load. A one-way analysis of variance and a post hoc paired t-test with a statistical significance level of 0.05 were performed. RESULTS: The humeral internal rotation decreased with a load at shoulder abduction between 40° and 90° on the scapular plane (P < 0.01, effect size: 0.15). No significant differences in scapular upward rotation (P = 0.57, effect size: 0.022), external rotation (P = 0.83, effect size: 0.0083) and posterior tilting (P = 0.74, effect size: 0.013) were observed between groups with and without a load. The main effect was not observed with and without a load (P = 0.86, effect size: 0.0072). However, the scapulohumeral rhythm was significantly greater without a load during shoulder joint abduction between 40° and 60° on the scapular plane. CONCLUSION: In RTSA patients, the glenohumeral joint was less internally rotated, and the scapulohumeral rhythm decreased under loaded conditions. It was stabilized against the load through the mechanical advantage of the deltoid muscle and other muscles.

Comparing in vivo three-dimensional shoulder elevation kinematics between standing and supine postures.

BACKGROUND: It is often assumed that body posture, standing vs. supine, changes shoulder muscle activation and range of motion, but these altered shoulder mechanics have not been objectively assessed. We expected the supine posture might facilitate scapular rotation and change subacromial pressure. The purpose of this study is to evaluate the influence of body posture on shoulder kinematics during arm elevation. METHODS: Ten males and eight females with a mean age of 33 years participated in this study. Shoulder kinematics were assessed during scapular plane elevation in the standing and supine postures by using single-plane fluoroscopic images. Kinematics were measured using 3-dimensional to 2-dimensional model-image registration techniques: matching the 3-dimensional bone model derived from computed tomography onto each fluoroscopic image. Glenohumeral superior/inferior translation, acromiohumeral distance, and scapular rotations were compared between the postures. The effect of sex also was evaluated. RESULTS: With the arm at the side position, the humeral head in the supine posture was located 0.5 mm superior compared to the standing posture (P < .001). During humeral elevation, the humeral head significantly shifted more inferiorly in the supine posture than in standing; the biggest mean difference was 0.6 mm, P = .003. But acromiohumeral distance during elevation was not significantly affected by the body posture (P = .05). Scapular upward rotation and posterior tilt were significantly different between the postures (P < .001). Sex had statistically significant, but quantitatively small, effects on shoulder kinematics. CONCLUSIONS: Body postures affect shoulder kinematics during humeral elevation. This knowledge will be useful to optimize rehabilitation exercises and for diagnostic insight.

Prevalence and significance of sleep disordered breathing in adolescent athletes.

Sleep disordered breathing (SDB) was more prevalent in adolescent athletes than expected, and several potential warning signs related to autonomic nerve activity appeared in SDB athletes. SDB screening may prevent associated downstream risks in the future. http://ow.ly/GQqK30nGm8r.

Arthroscopic Superior Capsular Reconstruction for Dislocation of the Shoulder with an Irreparable Rotator Cuff Tear: A Case Report.

CASE: A 49-year-old man presented with apprehension of a repeat dislocation after a left shoulder dislocation, which was accompanied by pain and restricted active range of motion of the shoulder. We performed an arthroscopic Bankart repair as well as an arthroscopic superior capsular reconstruction (ASCR) with fascia lata for the irreparable massive rotator cuff tear. Two years postoperatively, there was no shoulder pain or repeat dislocation; the range of motion had improved. CONCLUSION: We regard ASCR in combination with a Bankart repair as a useful treatment for recurrent shoulder dislocation that is accompanied by an irreparable massive rotator cuff tear.

Costal osteochondral autograft for reconstruction of advanced-stage osteochondritis dissecans of the capitellum.

BACKGROUND: Advanced-stage osteochondritis dissecans of the capitellum affecting the lateral wall may result in osteoarthritis, and suitable treatment is needed to avoid permanent deformation and impaired function. We aimed to assess postoperative outcomes of costal osteochondral autograft for treatment of this condition. METHODS: We included 22 young overhead athletes (mean age, 13.9 years) with advanced osteochondritis dissecans of the humeral capitellum who underwent costal osteochondral autograft. All patients had elbow pain and wide-range articular cartilage lesions. We evaluated clinical and radiographic outcomes at a mean follow-up of 27 months (range, 12-77 months). RESULTS: All patients achieved rapid functional improvement and returned to their former sports activity levels. The baseball players were able to play catch within 62 to 164 days (mean, 107 days) and returned to full pitching activity within 123 to 339 days (mean, 226 days). We assessed mean elbow function by the clinical rating system of Timmerman and Andrews and the Japanese Orthopaedic Association sports score; the scores improved from 121.5 and 53.7 points preoperatively to 169.2 points and 86.1 points, respectively, at the time of follow-up. Four patients required additional minor surgical procedures, including screw removal, loose body removal, and shaving off of spur formation. No patient showed obvious radiographic changes of osteoarthritis. All patients were satisfied with the final outcomes and had good functional recovery. CONCLUSION: Costal osteochondral autograft gave satisfactory results for advanced osteochondritis dissecans of the humeral capitellum with extensive lesions affecting the lateral wall.

[Examination of the shoulder joint using true anterior-posterior photography, employing a body surface index].

Radiographic examination of the anterior part of the shoulder includes routine anterior-posterior imaging that enables easy visualization of traumatic injuries and true anterior-posterior imaging that enables the visualization of intra-articular injuries. The X-ray incident angle of true anterior-posterior imaging is affected by physique and posture. However, in many reports, the angle is uniformly determined on the basis of the antero-posterior axis and the horizontal plane. We previously reported that the glenohumeral joint can be visualized with good reproducibility by establishing a reference line on the basis of three points on the body as indicators, namely the posterior view of the under-surface of the acromion, the coracoid process, and the inferior angle of the scapula. However, visualizing the undersurface of the acromion using physical indicators to set the angle for imaging remains problematic. In previous reports, the angle was consistently set at 20° to the horizontal plane, regardless of physique or posture, which resulted in poor reproducibility. After examining the imaging techniques described in previous reports, we describe here an imaging technique using a reference line based on indicators on the surface of the scapula that enables the glenohumeral joint and the undersurface of the acromion to be visualized with good reproducibility.

[Clinical study to obtain true view of the glenohumeral joint on scapula-45].

Scapula-45 is an original roentogenographical technique to clarify objectively the function of the rotator cuff and scapulothoracic joint. This examination enables assessment of the function of the rotator cuff and scapulothoracic joint utilizing the radiographs of the glenohumeral joint. However, in the former technique, it was difficult for the technician to properly align the patient for the view of the true glenohumeral joint because of the individual postural difference of the patients, such as kyphosis. In the present study, we reported a new technique with the use of the acromion, coracoid process, and inferior angle of the scapula as a landmark to obtain the consistent radiographs of the glenohumeral joint.

Surgical treatment for osteochondritis dissecans of the humeral capitellum.

BACKGROUND: Surgical treatments have been selected to treat advanced osteochondritis dissecans (OCD) of the humeral capitellum. PURPOSE: To evaluate the clinical results of surgical treatments for advanced capitellar OCD lesion and to clarify problems of poor clinical results. METHODS: Cases were reviewed for 27 patients with advanced OCD lesions treated operatively. All patients were male baseball players, with a mean of 13.3 years at the time of surgery. Drilling only was performed for 3 patients, fragment fixation for 13 patients, and removal of the detached fragment with drilling for four patients. Since 2004, reconstruction of the articular surface with use of osteochondral autograft from the rib has been performed for 7 patients with osteochondral defect. Mean follow-up was 37.4 months. Follow-up assessment included modified elbow rating system, evaluation of radiographs, and return to sports. RESULTS: Mean subjective score improved significantly from 70 to 96 postoperatively. Mean objective score improved significantly 71 to 81 postoperatively. A postoperative return to baseball was achieved by 25 patients. On the final radiographs, 4 patients showed flattening of >70% of the capitellum or degenerative changes, including insufficient remodeling of the lateral margin of the capitellum. Although patients could return to baseball, postoperative total arc of the elbow was decreased compared with the preoperative total arc. CONCLUSION: Surgical treatments were useful to restore advanced OCD lesions. Our results suggest that reconstruction of the lateral margin of the capitellum is important for achieving good clinical results. LEVEL OF EVIDENCE: Level 4.

Nonoperative treatment for osteochondritis dissecans of the capitellum.

BACKGROUND: Spontaneous healing potential and progression of osteochondritis dissecans of the capitellum have been unclear. HYPOTHESIS: Healing potential is high in the early stage of osteochondritis dissecans and low in the advanced stage. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: This retrospective study examines 39 patients with osteochondritis dissecans of the capitellum who were treated conservatively. All patients were baseball players (mean age, 12.8 years). After initial examination, all patients were advised to stop heavy use of the elbow. Physical and radiographic examinations were regularly performed and assessed. Mean duration of follow-up was 14.4 months. RESULTS: Early-stage lesions were present in 30 patients, while 9 patients were diagnosed with advanced lesions. Open capitellar growth plates were observed in 17 patients, and closed capitellar growth plates were seen in 22 patients. On final radiography, 25 of 30 early-stage lesions were assessed as healed. However, only 1 of 9 advanced-stage lesions was assessed as healed. The remaining 8 advanced lesions were unimproved or progressed. Healing of lesions was seen in 16 of 17 patients with an open growth plate and in 11 of 22 patients with a closed growth plate, representing a significant difference between patients with open and closed growth plates (P < .05). CONCLUSION: Spontaneous healing potential of osteochondritis dissecans in early lesions, especially in patients with open capitellar growth plates, appears high, and nonoperative treatment is appropriate. Conversely, healing potential is extremely low in advanced osteochondritis dissecans lesions. Surgical intervention is recommended to achieve lesion healing in advanced cases.

The influence of handheld weight on the scapulohumeral rhythm.

Scapulohumeral rhythm (SHR) provides insight to neuromuscular control and fundamental biomechanics of the shoulder. This rhythm often is disrupted in pathologic shoulders. As the first step, we sought to quantify SHR in healthy subjects for diagnostic assessment of shoulder function. Ten healthy shoulders were studied. Three-dimensional models of the humerus and scapula were created from computed tomography scans. Dynamic shoulder motion was recorded by use of single-plane fluoroscopy during arm abduction with 0-kg and 3-kg handheld loads. Shoulder kinematics were quantified by use of model-based 3-dimensional-to-2-dimensional registration techniques. SHR decreased (more scapular motion) with increasing abduction. With a 3-kg load, scapulothoracic motion was significantly reduced through the range of 35 degrees to 45 degrees of glenohumeral motion. Muscular stabilization of the scapula increased with external loading, as shown by decreased SHR during early lifting. Dynamic scapular stabilization provides a critical platform for upper extremity activity.

New intramedullary nail for the surgical neck fracture of the proximal humerus in elderly patients.

BACKGROUND: Fractures of the proximal humerus are common and the repair of displaced fractures generally requires an operative approach. In elderly patients, osteoporosis makes internal fixation problematic and frequently contributes to failed fixation and poor clinical results. We have developed a new intramedullary nail (pin lock nail) for the repair of surgical neck fractures of the proximal humerus in patients with osteoporotic bones. A retrospective review is presented of the cases of 19 elderly patients with two-part or three-part fractures of the proximal humerus treated using the pin lock nail. METHODS: We treated 19 elderly patients with a mean age of 70.5 years. There were 13 two-part surgical neck fractures, 3 two-part surgical neck fractures with non-displaced greater tuberosity fracture, and 3 three-part surgical neck fractures with greater tuberosity fracture. All fractures were treated using the pin lock nail. Clinical results were evaluated using the Japanese Orthopaedic Association score at the last follow-up examination. On radiographic evaluation, duration to bone union of the fracture, backing out of the pin and screw, penetration of the proximal pin, and varus angulations of the humeral neck were examined. RESULTS: Mean duration of follow-up was 14 months (range 6-54 months). All fractures had united at an average of 3.3 months after surgery. No backing out of the pin and screw or penetration of the proximal locking pin was seen at the time of last follow-up. Thirteen of the 16 patients had no or minimal varus angulations of the humeral neck (< or =10 degrees). The mean overall JOA score was 84.3 points (range 65.5-100). CONCLUSIONS: Our data show that using the pin lock nail for the treatment of two-part and three-part humeral fractures is a reliable procedure, providing good results with careful postoperative management.

Determination of in vivo glenohumeral translation using fluoroscopy and shape-matching techniques.

The purpose of this study was to investigate glenohumeral translation in-vivo during active shoulder abduction in the scapular plane. Three-dimensional (3D) models of 9 shoulders were created from CT scans. Fluoroscopic views aligned to the plane of the scapula were recorded during active arm abduction with neutral rotation. 3D motions were determined using model-based 3D-to-two-dimensional (2D) registration. Humeral translation was referenced to the glenoid center in the superior/inferior direction. The humerus moved an average of 1.7 mm superior with arm abduction, from an inferior location to the glenoid center. The humeral head was centered within 1 mm from the glenoid center above 80 degrees abduction. Variability in glenohumeral translation between shoulders decreased significantly from initial to final arm abduction. Our findings agree with some authors' observations of inferior-to-central translation of the humerus and behavior as a congruent ball and socket. We believe this information will help improve the understanding of shoulder function.