Biomedical subjects
Publications and source records attributed to J D Zuckerman.
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.
We examined the effect of the Gamma nail on strain distribution in the proximal femur, using ten cadaver femora instrumented with six unidirectional strain gauges along the medial and lateral cortices. The femora were loaded to 1800 N and strains were determined with or without distal interlocking screws before and after experimentally created two-part and four-part fractures. Motion of the sliding screw and the nail was also determined. Strain patterns and screw motion were compared with previously obtained values for a sliding hip screw device (SHS). The Gamma nail was shown to transmit decreasing load to the calcar with decreasing fracture stability, such that virtually no strain on the bone was seen in four-part fractures with the posteromedial fragment removed; increasing compression was noted, however, at the proximal lateral cortex. Conversely, the SHS showed increased calcar compression with decreasing fracture stability. The insertion of distal interlocking screws did not change the pattern of proximal femoral strain. The Gamma nail imparts non-physiological strains to the proximal femur, probably because of its inherent stiffness. These strains may alter bone remodelling and interfere with healing. Distal interlocking screws may not be necessary for stable intertrochanteric fractures.
The treatment of 25 tibias in 25 patients with posttraumatic chronic osteomyelitis was reviewed. The approaches to soft tissue management fell into three groups: 1) muscle flap coverage; 2) primary closure with suction irrigation; and 3) open cancellous bone grafting. Treatment success was judged by the presence or absence of drainage and the local signs or symptoms of infection, and by the status of the tibial nonunion. Overall, 19 of 25 tibias (76%) had successful treatment. We found flap coverage to have a higher success rate (80%) than either primary closure with suction irrigation (45.5%) or open cancellous bone grafting (40%). These results further attest to the refractory nature of chronic osteomyelitis.
The care of geriatric patients who sustain hip fractures is difficult because of associated medical comorbidities, the risk of medical and surgical complications, and the functional limitations that are often present before the fracture. The authors developed and used a comprehensive, interdisciplinary care program that has so far treated 431 geriatric hip fracture patients. The results of the program group were compared to a matched nonprogram group of patients (n = 60) cared for before the initiation of the program (and before the initiation of diagnosis-related groups). The program patients had fewer postoperative complications, significantly fewer (p less than .05) intensive care unit transfers (10.2% versus 20%), significantly improved (p less than .001) ambulatory ability at discharge (56.3% independent with assistive devices versus 18.2%), and proportionately fewer discharges to nursing homes (8.1% versus 19.3%). These results support the use of an interdisciplinary approach as a means of improving the inhospital care of geriatric hip fracture patients.
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.
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).
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.
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.
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Ferric hydroxide macroaggregates (FHMA) have been widely used as a carrier for several radionuclides used in radiation synovectomy. Different rates of extra-articular leakage of radioactivity have been observed with 90Y and 165Dy. In order to understand the mechanism(s) involved in the extra-articular leakage of radioactivity, the in vivo stability of FHMA carrier was studied. Following an injection of [59Fe]Fe-FHMA into the knees of normal rabbits, the cumulative leakage of [59Fe]Fe-FHMA was 2.9% at 5 days and 12.3% at 14 days. More than 60% of this activity was in the blood. But when FHMA was double labeled with 59Fe and 166Ho, the 59Fe leakage significantly increased to 18.5% at 5 days and 27% by 14 days. The instability of FHMA is accelerated when it is complexed with 166Ho and may be due to the "mass effect" of 166Ho or due to radiolysis induced by high energy beta particles from 166Ho. These results suggest that FHMA is a suitable carrier only for the short lived radionuclides used in synovectomy.
Revision of a glenoid component can be difficult in the presence of a humeral component. Removal of the humeral component is generally required, which adds significantly to the difficulty of the procedure and increases the risk of complications. This report describes revision of a loose glenoid component that was greatly facilitated by the presence of a modular humeral component.
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.
There is general agreement that the implant of choice for intertrochanteric fractures is the sliding hip screw (SHS). However, considerable differences of opinion exist as to which plate angle--varying from 130 to 150 degrees--is preferred. Thus far there has been no cadaver-based biomechanical analysis of this problem. To examine these questions, we determined the effect of plate angle on plate strain and proximal medial femoral strain distribution in cadaver femurs fixed with 130, 135, 140, 145, and 150 degrees SHS after experimentally produced stable and unstable intertrochanteric fractures. Twenty-four fresh adult cadaver femurs were assigned randomly to either the 130, 135, 140, 145, or 150 degrees SHS group. Each femur was radiographed and bone mineral density was determined by dual-photon absorptiometry. Multiple-strain gauges were affixed to the femur, with specific focus on the proximal femur and plate. Femurs were loaded at 25 degrees adduction in increments of 70 N from 0 to 1,800 N in a servohydraulic testing machine. Femurs were tested in a progressive manner: (a) intact femur; (b) intact femur with SHS inserted; (c) a stable two-part intertrochanteric fracture reduced with SHS; (d) a four-part fracture with the posteromedial fragment (PMF) reduced anatomically by a lag screw; (e) the same fracture with the PMF rotated 180 degrees and held in place by a lag screw to approximate a "near-anatomic" reduction; and (f) the same fracture with the PMF discarded. Screw sliding measurements were determined at regular intervals throughout each test.(ABSTRACT TRUNCATED AT 250 WORDS)
Joint and soft tissue injections may be the only way to differentiate various arthritic disorders, accurately identify a septic joint, and apply focused treatment. Certain considerations can make these injections safer and more effective. This article reviews the principles of diagnostic and therapeutic use of joint and soft tissue injections and makes specific recommendations for common injection sites. Also described are appropriate aseptic techniques for aspirating and injecting joints, bursae, and soft tissue, as well as the judicious use of corticosteroid injections in this age group.
Dysprosium-165-ferric hydroxide macroaggregates (165Dy-FHMA) was used as an agent of radiation synovectomy in an antigen-induced arthritis model in New Zealand white rabbits. Animals were killed up to 6 months after treatment. 165Dy-FHMA was found to have a potent but temporary antiinflammatory effect on synovium for up to 3 months after treatment. Treated knees also showed significant preservation of articular cartilage architecture and proteoglycan content compared with untreated controls, but only during the first 3 months after treatment. In animals killed 3 and 6 months after treatment there were only minimal differences between the treated and untreated knees, indicating that the antiinflammatory effects on synovial tissue and articular cartilage preservation were not sustained.
An unusual case of bilateral posterior fracture-dislocation of the hip (Pipkin Type IV) occurred in a 63-year-old man with Paget's disease of the pelvis. Other injuries included a displaced humeral shaft fracture and patellar ligament disruption. Bilateral cemented total hip arthroplasty was performed to avoid the need for prolonged immobilization. Postoperative low-dose irradiation was used because of the risk of heterotopic ossification.
Infection following total knee arthroplasty can be one of the most challenging problems in orthopaedic surgery. This article discusses the pertinent clinical factors to be considered and the treatment options in the management of patients with infection following total knee replacement.