Faculty Bibliography

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

Medial dislocation of the long head of the biceps branchii tendon is a rare occurrence and is often associated with degenerative or traumatic tears of the rotator cuff, specifically tears of the subscapularis tendon. Following a dislocation, the biceps tendon will assume either an intra- or extra-articular position depending on whether or not the subscapularis tendon detaches from its humoral insertion. Magnetic resonance imaging (MRI) has been found to provide valuable information concerning the location of the biceps tendon and the integrity of the rotator cuff. In this report, three patients with suspected dislocations of the biceps tendon are evaluated using MRI

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

Bilateral shoulder motor output measurements were obtained in 40 subjects with a Biodex dynamometer. The subjects included two groups, a younger group (20 to 30 years) and an older group (50 to 60 years). They were engaged in low to moderate levels of occupational and spare-time physical activity. Each subject performed three maximum effort shoulder movements in flexion/extension, abduction/adduction, and internal/external rotation at 60 degrees/sec and 120 degrees/sec. Side tested, axis, and speed were randomly selected. The findings indicate that a significant decline occurred in peak torque, work, and power for all axes of movement at both speeds when the older group was compared with the younger group. A decline in peak torque and work and a corresponding increase in power resulting from an increase in speed occurred in both age groups. The effect of age was the same at 60 degrees/sec and at 120 degrees/sec. Overall, no difference in dominant and nondominant motor function was seen in either the younger or older untrained men

Forty-two consecutive patients (20 men and 22 women, age range 39 to 78 years) with full-thickness rotator cuff tears underwent a comprehensive isokinetic strength assessment before and at 3-month intervals for 1 year after surgery. All patients underwent acromioplasty and rotator cuff repair and were treated with a standardized postoperative rehabilitation program. Isokinetic strength testing was performed in flexion/extension, abduction/adduction, and external/internal rotation at 60 degrees/sec. The unaffected contralateral shoulder was tested for comparison. Clinical outcomes were assessed with the University of California Los Angeles Shoulder Rating Scale (maximum = 35 points). The average University of California Los Angeles score was 31.2 by 1 year after operation. Patients with small and medium tears had an average rating of 33.5, whereas those with large and massive tears had an average score of 28.3. Strength increased gradually during the first postoperative year. The preoperative mean peak torque was 54%, 45%, and 64% of the uninvolved shoulder in flexion, abduction, and external rotation, respectively; after operation it increased to 78%, 80%, and 79% by 6 months and 84%, 90%, and 91% by 12 months. The greatest improvement in strength consistently occurred during the first 6 months after surgery. Patients also showed marked increases in both work and power. By 12 months after operation mean work had increased to 70% in flexion and abduction and 90% in external rotation of the uninvolved shoulder. Similarly, mean power had increased to 68%, 79%, and 90% of the uninvolved shoulder in flexion, abduction, and external rotation, respectively, by 12 months after operation. Recovery of strength correlated primarily with the size of the tear: for small and medium tears recovery of strength was almost complete during the first year, and for large and massive tears it was much slower and less consistent. By using isokinetic strength evaluation we found that recovery of strength after rotator cuff repair requires at least 1 year of rehabilitation

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

Five hundred and sixteen community-dwelling, ambulatory, geriatric hip fracture patients who were independent prior to fracture were followed prospectively to determine which patients regained their prefracture independent living status at 3-, 6-, and 12-month follow-up. At 3-, 6-, and 12-month follow-up, 78, 77, and 76% of the patients, respectively, had regained their prefracture independent living status. Analysis was performed to determine which pre- and postinjury factors were predictive of a patient regaining prefracture independent living status at 3, 6, and 12 months after fracture. Patients who were younger than age 85, independent in activities of daily living prior to fracture, independent in ambulation at hospital discharge, and who had three or more medical comorbidities were more likely to regain their prefracture independent living status