Faculty Bibliography

We performed an anatomic study of 140 cadaver shoulders to correlate the influence of the coracoacromial arch anatomy on full-thickness rotator cuff tears (RCTs). The presence, location, and size of RCTs were initially documented. After dissection was complete 14 dimensional parameters, including humeral head size, glenoid size, and location of bony landmarks, were obtained by direct measurement. These data were entered into a computerized data base and 24 additional parameters (lengths, angles, areas) were calculated. The data were then subjected to analysis of variance and paired and unpaired t tests to determine correlation between the multiple parameters, age, sex, and left-to-right variance with RCTs. Three-dimensional computer modeling was then used to investigate the role of humeral head position in defining the available space within the coracoacromial arch (supraspinatus outlet). Overall 20% of the cadaver group exhibited full-thickness RCTs. The age group 60 years and older had a 29% incidence of RCTs compared with 5% in the group less than 60 years of age. The RCT group had a significantly greater anterior projection of the acromion than had the intact group (difference = 3.8 mm, p < 0.007). Acromial tilt was 28.5 degrees in the RCT group and 33.5 degrees in the intact group (p < 0.007). The supraspinatus outlet area was calculated by determining the total coracoacromial arch area and subtracting the area of the humeral head within the coracoacromial arch. The supraspinatus outlet was 22.5% smaller in the RCT group (p < 0.07). By using a series of measured and calculated parameters, we were able to characterize the anatomy of the coracoacromial arch and its relationship with the humeral head and to correlate variations in structure with the presence of RCTs. These findings may aid in our understanding of outlet impingement as a factor in the cause of RCTs.

We report the case of a 28-year-old woman who developed signs and symptoms of brachial-plexus neurapraxia eight years after a type III acromioclavicular (AC) joint separation. Stabilization of the AC joint resulted in resolution of the symptoms

A cadaver study was performed to determine the effect of arm position and capsular release on rotator cuff repair. Artificial defects were made in the rotator cuff to include only the supraspinatus (small) or both supraspinatus and infraspinatus (large). The defects were repaired in a standard manner with the shoulder abducted 30 degrees at the glenohumeral joint. Strain gauges were placed on the lateral cortex of the greater tuberosity and measurements were recorded in 36 different combinations of abduction, flexion/extension, and medial/lateral rotation. Readings were obtained before and after capsular release. With small tears, tension in the repair increased significantly with movement from 30 degrees to 15 degrees of abduction (p < 0.01) but was minimally affected by changes in flexion or rotation. Capsular release significantly reduced the force (p < 0.01) at 0 degree and 15 degrees abduction. For large tears, abduction of 30 degrees or more with lateral rotation and extension consistently produced the lowest values. Capsular release resulted in 30% less force at 0 degree abduction (p < 0.05)

Intrinsic disorders that can cause shoulder pain include arthritis, gout, pseudogout and osteonecrosis. In its mildest form, impingement syndrome may cause only minimal discomfort. At its worst, impingement syndrome may lead to rotator cuff tear. Bicipital tendinitis and rupture of the biceps tendon may also be associated with impingement. Early rehabilitative intervention is important. Physical therapy is directed toward restoring range of motion and muscle strength

Shoulder disorders are most commonly manifested by pain and limited function. Careful history and examination help the physician localize the problem to the shoulder joint, the surrounding tissues or adjacent sites that can cause referred pain to the shoulder. Common extrinsic causes of shoulder pain include postural problems and cervical spine disorders

We present a case of suppurative arthritis occurring in a patient with bilateral osteonecrosis of the femoral head. Predisposing factors were chronic alcoholism (osteonecrosis) and septicemia due to intravenous drug abuse (suppurative arthritis). Although the association of suppurative arthritis and osteonecrosis is rarely reported in the literature, the prevalence of osteonecrosis and of various factors predisposing to the development of suppurative arthritis should remind us of the possibility that a patient with osteonecrosis who develops sudden worsening of joint pain or fever may have developed suppurative arthritis of the affected joint, particularly when there is evidence of bone destruction

Hardware failure of the sliding screw system used in hip fracture fixation is rare. The fatigue failure of the sliding screw is always related clinically to nonunion or refracture along the path of the screw. In both situations, cyclic loading of the implant exceeds its endurance limit, and failure can ensue. Three cases of failure of the sliding screw are presented: a nonunion of a basicervical fracture, a nonunion secondary to stress fracture at the plate-barrel junction, and a refracture through the femoral neck after healing of an intertrochanteric fracture. A biomechanical analysis of the stresses on the sliding screw focuses on design features such as the internal threaded region used for the compression screw or the barrel length that creates increased stresses in the screw, thus lowering the number of cycles to failure. Based on this analysis, recommendations are made concerning implant design and surgical technique

Two cases of polyethylene bearing failure in the Triaxial elbow are presented. Although these were low-demand patients with the prostheses properly aligned, the severity of the wear suggests inadequate prosthesis design