Julian Sosner

The instrumented walker : usage patterns and forces

Studies documenting the forces that are transmitted through a walkers frame are still scant. The purpose of this study was to evaluate the pattern and magnitude of forces that are transmitted through the frame of a walker during ambulation. A standard aluminum walker was instrumented. Gauges, which were mounted on all four legs, recorded axial, frontal, and sagittally oriented forces. A custom made computerized system registered the forces during 30 seconds of data acquisition. Twelve patients with ambulation dysfunction were tested with this system. Two different usage patterns emerged from the study. One usage pattern was observed in patients who were using the walker as a mean to reduce the amount of weight transmitted through the lower extremity. The second pattern was observed in patients with severe balance problems. These patients used the walker to enhance their balance and stability. The system described allows walker usage pattern analysis. Better understanding of force distribution and usage patterns may lead to improved or new walker design.

Heterotopic ossification: Treatment of established bone with radiation therapy

Ectopic bone formation or heterotopic ossification (HO) is frequently seen on rehabilitation units after total hip arthroplasties, burns, and neurological injuries. Currently the major role for treatment is in prophylaxis and the major methods include anti-inflammatory medications, irradiation, and diphosphanate administration. These prophylactic measures are generally considered to be ineffective for the treatment of ectopic bone once it has already formed. We describe two cases of HO for which a radiation therapy protocol was used to treat established, ectopic bone after it had become problematic. Both patients were found to have increased range of motion and decreased complaints of pain after treatment, though no gross plain film x-ray changes were noted. We conclude that radiation therapy may be useful not only for prophylaxis of heterotopic ossification but for ectopic bone after it has been formed, especially when pain and progressively decreased range of motion are problematic.

Progressive supranuclear palsy: Clinical presentation and rehabilitation of two patients

Progressive supranuclear palsy (PSP), is an infrequent movement disorder characterized by supranuclear ophthalmoplegia, pseudobulbar palsy, and axial dystonia with frequent and unpredictable falls, usually backward. Median survival from time of diagnosis is two years. When diagnosis is reached, the patients are usually disabled and unable to ambulate independently. No specific rehabilitation protocol has been described for PSP. This article examines our rehabilitation experience with two PSP patients and our management of their frequent and unpredictable falls. The rehabilitation program consisted of a thorough physical evaluation; cognitive and speech evaluation and training; exercises to improve strength and coordination; and static and dynamic balance training. In order to improve safety during ambulation, we provided the patients with a heavy shopping cart or wheelchair that they could grab when in danger of losing their balance. The patients were able to achieve independence in ambulation.

Total knee arthroplasty in Parkinson's disease.

Total knee arthroplasty in Parkinsons disease (PD) has been reported only twice in the literature. Parkinsons disease is considered a contra-indication for total knee replacement by some authors. We report on a 77-year-old man with PD who underwent total knee arthroplasty for severe degenerative joint disease. The patient had a somewhat prolonged but successful rehabilitation as an inpatient and continued to make gains following discharge. Currently he is an independent functional ambulator. Based on our experience with this patient, we recommend that patients with PD who maintain ambulatory function prior to surgery and are cognitively able to integrate new knowledge and follow commands should be considered candidates for total knee replacement if it is indicated. Our patient demonstrates, however, that even in patients suffering from mild PD the rehabilitation process may be significantly prolonged and more difficult than in patients without PD. Objective studies evaluating the role of pre-surgical rehabilitation are needed.

Lumbar Spinal Strains Associated with Whiplash Injury: A Cadaveric Study

Fast A, Sosner J, Begeman P, Thomas MA, Chiu T: Lumbar spinal strains associated with whiplash injury: A cadaveric study. Am J Phys Med Rehabil 2002;81:645–650. Objectives To study and quantify the effects of rear-end collision on the lumbar spine. Design The lumbar spine of a cadaver was instrumented with rosette strain gauges applied on the lateral and anterior surfaces of T12, L2, and L4. Biaxial accelerometers were mounted on L1, L3, and L5. The cadaver was seated, restrained, and subjected to rear impacts of 5 g and 8 g. Results The anterior shear strains had a biphasic shape. Spinal strains peaked at the T12 at approximately 120 and 370 msec, whereas in the L4 vertebra, it peaked at 200 and 380 msec. The anterior strain pattern of the L4 and T12 vertebrae were in diametrically opposite directions. In the second set of tests (8 g experiment), the acceleration forces and strains pattern were similar to the 5 g test but of higher magnitude. The principal anterior strain was 480 &mgr;m/m for 5 g and 530 &mgr;m/m for 8 g; the lateral shear strain was 680 &mgr;m/m and 1500 &mgr;m/m in the 5 g and 8 g experiments, respectively. Conclusions Forces generated during simulated whiplash collision induce biphasic lumbar spinal motions (increased-decreased lordosis) of insufficient magnitude to cause bony injuries, but they may be sufficient to cause soft-tissue injuries.

Odontoid Fracture and C1-C2 Subluxation in Psoriatic Cervical Spondyloarthropathy: A Case Report

Study Design Case presentation and review of pertinent literature. Objectives To present an unusual case and alert other physicians to possible missed diagnoses. Summary of Background Data An unusual case is presented of a young man with severe psoriatic spondyloarthropathy and fusion of C2‐C7 (Type II cervical psoriatic ankylosing disease) who fell at home, sustaining an unrecognized fracture of the odontoid process leading to subluxation of C1‐C2 and transitory tetraplegia. The patient presented with torticollis, and the fracture was unrecognized for a long period of time. Methods Case presentation. Results This patient became independent in all activities of daily living after surgery and rehabilitation despite persistence of torticollis. Conclusions A patient who presents clinically with traumatic torticollis after minor trauma and who also has psoriasis and ankylosis of the cervical spine should be suspected of having a fracture‐subluxation until definitely proven otherwise. In the present case, the late diagnosis delayed surgical stabilization.

Forces, moments, and accelerations acting on an unrestrained dummy during simulations of three wheelchair accidents

To determine the magnitude and distribution of the forces, moments, and accelerations acting on an individual sitting in a wheelchair during three possible accidents occurring while negotiating a sidewalk curb, experimental trials were performed in a bioengineering laboratory using a 50th percentile Hybrid III dummy seated in a standard wheelchair. A ramp was designed with an adjustable incline to allow the wheelchair to reach the edge of a sidewalk height platform at the desired forward speed of 2.5 miles per hour (comfortable walking speed). The wheelchair velocity was monitored via an optical pickup. Three types of accidents were simulated: (1) a wheelchair hitting straight into a curb; (2) a wheelchair falling forward straight off a curb; (3) a wheelchair falling diagonally off a curb. Each experiment was repeated three times. Each run was photographed using high-speed cameras and videotaped from three perspectives: frontal, lateral, and overhead. The results were averaged and compared with published injury Assessment Values (IAV) and Head Injury Criteria (HIC). Of significance were the following results. In the straight into a curb experiments, the wheelchair remained upright and the dummy seated. Low magnitude forces (23-73 N), moments (1-12 Nm), and accelerations (0.2-1 G) were recorded at the neck and head. The HIC was low at 0.3. These results were of no clinical significance. In the straight off a curb experiments, properly attached footrests prevented the wheelchair from toppling over but did not prevent the dummy from falling off the wheelchair. Forces (187-4,176 N), moments (3-178 Nm), and accelerations (131-206 G) of great magnitude were recorded at the head and neck when the dummy fell off the wheelchair. These values were above IAV. The HIC was 960. In the diagonally off a curb experiments, both the wheelchair and the dummy fell sideways. High-magnitude forces (274-2,313 N), moments (4-110 Nm), and acceleration (140-236 G) were recorded in the head and neck regions. The HIC was 975. These values were close to IAV and may signify potential serious injuries.

Forces, moments, and acceleration acting on a restrained dummy during simulation of three possible accidents involving a wheelchair negotiating a curb: Comparison between lap belt and four-point belt

The objective of this study was to determine the effect of two types of restraining belts (lap belt and a four-point belt) on an instrumented dummy during three situations: wheelchair hitting straight into curb (SIC); wheelchair falling straight off a curb (SOC); wheelchair falling diagonally off a curb (DOC). A fully instrumented (50th percentile Hybrid III) dummy was seated in a standard wheelchair and restrained with one of the belts. The wheelchair rolled down a ramp reaching a platform at 2.4 miles per hour (comfortable walking speed). Three types of experiments were performed: SIC, SOC, DOC. Each experiment was repeated at least three times. Forces, moments, and acceleration were monitored and recorded via 48 sensors placed at the head, spine, and limbs. All experiments were videotaped and photographed. The data were averaged and compared with standards that have been previously established in car crash testing and with data recently obtained in a similar study using a nonrestrained dummy. Our results showed that in the SIC experiments, low magnitude forces, moments, and acceleration of no clinical significance were recorded with both types of belts. The wheelchair remained upright and the dummy safely seated. In the SOC experiments, the two belts prevented the dummys ejection from the chair and, thus, have been effective in lowering the forces, moments, and acceleration and preventing significant injuries to the head and neck regions. In the DOC experiments, the lap belt proved to be somewhat more effective than the four-point belt in lowering the extension forces at the upper neck and the moments at the lower neck below injury levels. It also kept the head injury criteria well below injury level. We postulate that the four-point belt was less effective because of its more extensive body fixation, which leads to concentration of moments and forces at the head and lower neck regions. The results of this study show that restraining systems can enhance the safety of wheelchair occupants in certain incidents. It has been demonstrated that the lap belt is as effective as the four-point belt system in SIC and SOC incidents. In DOC falls, neither belt could prevent falls and trauma to the head and neck region. The lap belt, however, was somewhat superior. We recommend that wheelchairs be equipped with a lap belt and patients be encouraged to buckle-up while using the wheelchair outdoors.