Faculty Bibliography

Neuropathic arthropathy is a chronic, progressive degenerative disorder affecting one or more peripheral or vertebral articulations, which develops as the result of a disturbance in the normal sensory (pain or proprioceptive) innervation of joints. Diabetes, syphilis, and syringomelia are the most commonly associated clinical entities. When neuropathic arthropathy is suspected, careful clinical evaluation should be performed to identify an underlying neurologic disorder. Patient education, joint protection, and early recognition of fractures are the most important general management principles. Surgery can be considered in cases of advanced joint destruction when there is significant disability

An unconstrained cadaver ankle model was designed to reevaluate the effect of ankle mortise widening and syndesmotic fixation on the load-bearing characteristics of the tibiotalar joint. Tibiotalar contact area, centroid shift, and mean contact pressure were quantified using a pressure-sensitive film technique. Six fresh-frozen below-knee amputation specimens were axially loaded with 500 N in three positions: neutral, 10 degrees of dorsiflexion, and 20 degrees of plantarflexion. The tibiotalar contact area and centroid position for each specimen in its intact state were first determined and then compared with values obtained after syndesmotic fixation, mortise widening of 2 and 4 mm, and deep deltoid ligament transection. Syndesmotic fixation significantly decreased joint contact area but did not consistently affect centroid position. However, unlike earlier studies, which used more constrained ankle fracture models, mortise widening with or without deltoid rupture was not found to significantly affect contact area, centroid position, or joint contact pressure. When statically loaded, the talus moved to its position of maximal congruence in the mortise, rather than displacing laterally along with the lateral malleolus

OBJECTIVE: A biomechanical cadaver study was performed to compare the stability and ultimate strength of ten standard fixation techniques used for the treatment of surgical neck fractures of the proximal humerus. DESIGN: One hundred twenty (60 fresh frozen, 60 embalmed) proximal humerus specimens were selected and divided into two groups: fresh frozen specimens represented a nonosteopenic group and embalmed specimens an osteopenic group. Simulated fractures were created at the level of the surgical neck, reduced, and randomly assigned to one of ten methods of fixation (six fresh frozen and six embalmed specimens per fixation group). These constructs were then mechanically tested with the humeri oriented to create primarily shear loading of the fixation. RESULTS AND CONCLUSIONS: The T-plate and screws provided significantly stronger fixation (p < 0.005) in the fresh frozen specimens than all other methods. The Ender nails/tension band construct was the second strongest fixation technique, providing significantly stronger fixation (p < 0.01) than all the remaining techniques. Four Schanz pins with one pin placed through the greater tuberosity followed by the T-plate and screws provided the strongest fixation in embalmed specimens. Tension band fixation in both humeral groups was shown to provide the least effective fixation

A laboratory study was performed to compare the stability and ultimate strength of three standard fixation techniques for split-type lateral tibial plateau fractures. The three methods of fixation were (a) three 6.5-mm cancellous lag screws with washers; (b) two 6.5-mm cancellous lag screws with washers and an additional antiglide 4.5-mm cortical screw with washer; and (c) six-hole L-shaped buttress plate. Twelve pairs of embalmed mildly osteopenic lower extremities were used. Simulated split-type lateral tibial plateau fractures were created, reduced, and then instrumented in a matched pair design. The instrumented specimens were axially loaded to determine resistance to displacement, cyclically loaded to 10,000 cycles to determine dynamic stability, and then loaded to failure. There were no statistically significant differences found between resistance to displacement or failure strength as a function of either fragment size or sample bone density. On the basis of biomechanical stability, there appears to be no difference between the three fixation techniques tested. The results of this study suggest that use of an antiglide screw or buttress plate does not offer an advantage over lag screw fixation alone for the treatment of split type lateral tibial plateau fractures

A telemeterized shoulder prosthesis was developed and tested, first in vitro and then in a cadaver implantation. The prototype prosthesis was instrumented with 3 strain gauges fixed within a hollow, tapered neck element whose output was used to determine the load vectors experimentally applied to the humeral head. Testing demonstrated accuracy of force measurement resolution to within 5% of actual applied forces. This design seems feasible for further investigations to develop a totally implantable telemeterized prosthesis

A prospective analysis was performed involving 680 geriatric patients with hip fractures to determine whether the demographic profile of patients with femoral neck fractures was similar to that of patients with intertrochanteric fractures. All patients were community dwelling, cognitively intact, previously ambulatory elderly with femoral neck or intertrochanteric fracture. Three hundred fifty-eight patients (52.6%) sustained a femoral neck fracture; 322 (47.4%), an intertrochanteric fracture. Patients with an intertrochanteric fracture were significantly older, more likely to be limited to home ambulation, and were more dependent regarding basic and instrumental activities of daily living. After stratification by gender and adjustment for age, these differences remained significant in women only. There were no differences in age, prefracture ambulatory ability, or dependence in activities of daily living in men with either type of fracture

A prospective, randomized, controlled, double-blind clinical study was performed to determine the short-term efficacy of subacromial injection of corticosteroids for the treatment of subacromial impingement syndrome. Forty patients were randomized to receive either six milliliters of 1 per cent lidocaine without epinephrine (the control group) or two milliliters containing forty milligrams of triamcinolone acetonide per milliliter with four milliliters of 1 per cent lidocaine without epinephrine (the corticosteroid group). The patients were re-examined serially until completion of the study. Nineteen patients, whose mean age was fifty-six years (range, thirty-two to eighty years), were randomized to the corticosteroid group, and twenty-one patients, whose mean age was fifty-seven years (range, thirty-two to eighty-one years), were randomized to the control group. The mean duration of symptoms before the injection was eight months for both groups. Eighteen patients in the corticosteroid group and nineteen patients in the control group had moderate or severe pain before the injection. At the most recent follow-up evaluation, at a mean of thirty-three weeks for the corticosteroid group and twenty-eight weeks for the control group, three patients in the corticosteroid group had moderate or severe pain, compared with fifteen patients in the control group. The mean active range of forward elevation and external rotation improved by 24 and 11 degrees, respectively, for the corticosteroid group and by 10 and 5 degrees, respectively, for the control group. We concluded that subacromial injection of corticosteroids is an effective short-term therapy for the treatment of symptomatic subacromial impingement syndrome. The use of such injections can substantially decrease pain and increase the range of motion of the shoulder

A prospective study was performed to determine the reliability of analysis of intraoperative frozen sections for the identification of infection during 175 consecutive revision total joint arthroplasties (142 hip and thirty-three knee). The mean interval between the primary and the revision arthroplasty was 7.3 years (range, three months to twenty-three years). To reduce selections bias, tissue was obtained for frozen sections during all revisions in patients who did not have active drainage from the wound or a sinus tract. Of the 175 patients, twenty-three had at least five polymorphonuclear leukocytes per high-power field on analysis of the frozen sections and were considered to have an infection. Of these twenty-three, five had five to nine polymorphonuclear leukocytes per high-power field and eighteen had at least ten polymorphonuclear leukocytes per high-power field. The frozen sections for the remaining 152 patients were considered negative. On the basis of cultures of specimens obtained at the time of the revision operation, nineteen of the 175 patients were considered to have an infection. Of the 152 patients who had negative frozen sections, three were considered to have an infection on the basis of the results of the final cultures. Of the twenty-three patients who had positive frozen sections, sixteen were considered to have an infection on the basis of the results of the final cultures; all sixteen had frozen sections that had demonstrated at least ten polymorphonuclear leukocytes per high-power field. The sensitivity and specificity of the frozen sections were similar regardless of whether an index of five or ten polymorphonuclear leukocytes per high-power field was used. Analysis of the frozen sections had a sensitivity of 84 per cent for both indices, whereas the specificity was 96 per cent when the index was five polymorphonuclear leukocytes and 99 per cent when it was ten polymorphonuclear leukocytes. However, the positive predictive value of the frozen sections increased significantly (p < 0.05), from 70 to 89 per cent, when the index increased from five to ten polymorphonuclear leukocytes per high-power field. The negative predictive value of the frozen sections was 98 per cent for both indices. The current study suggests that it is valuable to obtain tissue for intraoperative frozen sections during revision hip and knee arthroplasty. At least ten polymorphonuclear leukocytes per high-power field was predictive of infection, while five to nine polymorphonuclear leukocytes per high-power field was not necessarily consistent with infection. Less than five polymorphonuclear leukocytes per high-power field reliably indicated the absence of infection