PubMed · 6859640
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L Seeder. 1983. Muscle strength grading.. https://doi.org/10.1016/s0196-0644(83)80492-2
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OBJECTIVE: This study aimed at investigating the effects of sitting posture on ischial pressure and pelvic orientation for two types of cushions. DESIGN: Two types of seating devices, Roho and Polyurethane (PU) Foam cushions, six predefined postures, and two subject groups, Normal and Paraplegic, were tested. Ischial pressure and pelvic orientation were monitored. The sequence in which the cushions were tested were randomized, and the postures were tested according to a preplanned sequence. SETTING: The experiments were carried out in the laboratory of a rehabilitation engineering centre in Hong Kong. PARTICIPANTS: Six paraplegic subjects (referred sample) and 8 normal volunteers were tested. At the time of study, no subjects showed any signs of pressure sore or other health problems. MAIN OUTCOME MEASURES: It was hypothesized that sitting posture could significantly affect pelvic orientation as well as pressure distribution. It was also hypothesized that cushion selection was a critical factor in compensating the adverse effects of postures on pressure distribution. RESULTS: With the paraplegic group, the maximum ischial pressure recorded on Roho for various postures ranged from 88 mmHg for the Trunk-Bent-Forward (PF) posture to 146 mmHg for the Trunk-Bent-Right (PR) posture, whereas on PU foam cushions, the values ranged from 106 mmHg for the PF posture to 221 mmHg for the PR posture. With the paraplegic subjects sitting with their trunks bent laterally, it was found that the mean pressure difference between the left and right ischial tuberosities was more prominent on the PU foam cushion than on the Roho. CONCLUSION: Sitting posture can significantly affect pelvic orientation and ischial pressure. This study was also showed that the Roho cushion was significantly more efficient in compensating the adverse effects of sitting posture on pressure distribution.
Microfixation and wire fixation techniques were used in combination with miniplates in the stabilization of simulated simple zygoma fractures in four fresh human cadaver heads. An orthogonal conveyer and rigid steel test frame were used to test rotational stability after deforming forces were applied. After testing multiple combinations at an initial deforming force of 5 kg, selected combinations were tested over a range of 2 to 22 kg. Evaluation of force-displacement data revealed that three-point fixation with miniplates was superior to all other methods, in agreement with previous studies. The combination of lateral buttress miniplate fixation in conjunction with microfixation at the zygomaticofrontal and infraorbital rim regions exhibited stable characteristics over the range of forces applied. Miniplate-microplate combinations exhibited greater stability than corresponding miniplate-wire combinations. The combination of miniplate-microplate fixation clinically allows a balance between stability and aesthetics in selected zygoma fractures.
The purpose of this study was to determine the effect of patellar bone and patellar implant thickness on patellofemoral forces after resurfacing in total knee arthroplasty. Seven cadaver knees were tested using an Oxford Knee Testing Rig. This model gave the specimens 6 degrees freedom while dynamic data were collected. Each knee was tested from full extension to 95 degrees knee flexion. Knees were implanted with Press Fit Condylar femoral, tibial, and patellar implants. The effect of varying patellar thickness on patellofemoral forces was determined by using custom modular oval-domed polyethylene patellar components with progressive thickness increments of 2 mm. Patellofemoral forces were measured by a custom-designed uniaxial patellar load cell. Statistically significant increases in patellofemoral compression forces were found from 70 degrees to 95 degrees flexion with increased patellar bone and patellar implant thickness.