Shimazu A

Electrophysiological studies of intermittent claudication in lumbar stenosis.

To clarify the pathophyslology of intermittent claudication In 37 patients with lumbar spinal stenosis, neural function was evaluated by examining somatosensory evoked potentials (stress-SEPs), and nerve action potentials (stress-NAPs) before and after walking stress. It was shown preoperatively that the stress-SEPs became abnormal Immediately after walking In 31 of 37 patients. In seven of nine operated patients, the assessment clearly shows that SEPs had reverted to normal after surgery. The present method Is nonlnvaslve, simple In technique, painless, and safe, a procedure therefore that is useful as the Initial step in the diagnosis and treatment of patients with lumbar canal stenosis. It also may help to differentiate neurogenic from vascular intermittent claudication.

Prostaglandin E1 as a hypotensive drug during general anesthesia for total hip replacement

STUDY OBJECTIVE To determine the effect of intravenous administration of prostaglandin E1 (PGE1) in inducing controlled hypotension during general anesthesia. DESIGN Randomized, prospective study. SETTING Inpatient surgery at a university hospital. PATIENTS 57 ASA physical status I and II patients scheduled for total hip replacement. INTERVENTIONS In 29 patients undergoing total hip replacement, PGE1 (0.11 +/- 0.03 micrograms/kg/min) was infused to induce hypotension during general anesthesia with enflurane, isoflurane, or sevoflurane in nitrous oxide and oxygen. In another 28 patients, the control group, normotensive anesthesia was performed for the same procedure. MEASUREMENTS AND MAIN RESULTS Systolic blood pressure decreased significantly (p < 0.01) from 136 +/- 22 mmHg to 93 +/- 10 mmHg during PGE1 infusion, although heart rate did not change significantly. Arterial hemoglobin oxygen saturation showed a mild but significant decrease (p < 0.05) during PGE1 infusion. Blood loss (480 +/- 132 ml) and blood transfusion (280 +/- 260 ml) during surgery were significantly less in patients with hypotensive anesthesia (p < 0.01 and p < 0.05, respectively) than in patients with normotensive anesthesia (667 +/- 326 ml and 468 +/- 395 ml, respectively). Blood loss and blood transfusion after surgery were similar in both groups. In the recovery room or surgical ward, 3 of 29 patients with hypotensive anesthesia needed rapid blood transfusion because of moderate hypotension. The volume of urine during surgery was significantly less (p < 0.05) in the control group. Two patients developed mild phlebitis at the site of the PGE1 infusion, but there were no serious side effects. CONCLUSION These data suggest that PGE1 can be used safely to induce hypotension, thereby reducing blood loss during total hip replacement with general anesthesia.

Specific serum antibodies against membranous proteins of a human immortal chondrocytic cell line (HCS-2/8) in rheumatoid arthritis and their relationship to the natural history of this disease

An immortal human chondrocytic cell line (HCS-2/8) derived from a chondrosarcoma was used as a source of human antigens to find humoral antibodies to cell surface proteins of human chondrocytes in sera from patients with rheumatoid arthritis (RA). Membrane fractions prepared from the cell line were subjected to Western blot analysis using RA and normal sera as probes. RA sera recognized about a dozen bands, but three of these bands, with molecular weights of 105 kDa, 65 kDa, and 47 kDa, were found to be specific for the RA sera (P<0.05). These bands disappeared following V8 protease digestion, indicating that they were proteins. Among patients with 4 years or more of RA disease activity, reactivity against 105-kDa and 68-kDa proteins was relatively high in those whose joints showed a high degree of erosion. We suspect that levels of these two antibodies are suggestive of changes associated with the natural course of RA.

Intraoperative Evaluation of Component Stability in Total Knee Arthroplasty

Information concerning component stability immediately following total knee arthroplasty (TKA) must be reliable. To this end, we developed a measurement system for tibial component, which is thought to be the most frequent loosening component, using three non-contact displacement transducers fixed on the tibial cortex. The measurement system consists of three parts: A device which is connected to the tibial component and has three steel plates, a sensor unit, and an external fixator which connects the sensor unit to the tibial shaft. A load is applied with a push-pull gauge from which a voltage output is supplied to the A–D converter. Sampled data are calculated as displacements by a personal computer that displays the tibial component micromotion data on a cathode ray tube (CRT).

Impaired sensory conduction in a mixed nerve induced by high frequency stimulation of the muscle fibres. An experimental study in cats.

To see if symptoms such as sensory disturbance or numbness worsen during exercise as is thought to occur in entrapment neuropathy, we studied the interaction between sensory and muscle nerve fibres in a mixed nerve in cats. Stimulation electrodes were placed on both the deep (muscle) and superficial (sensory) branch of the radial nerve at the elbow. High frequency stimulation at 100 Hz was applied to one branch for five minutes and the nerve action potential of the other branch was recorded at the axilla where the radial nerve is mixed. The stimulation decreased the amplitude of the nerve action potential and prolonged its latency. Recovery from these changes was gradual, and changes were the same whichever branch was stimulated. When a cats leg was made ischaemic, the changes were more pronounced. The changes in the nerve action potential may have arisen from ischaemia in the nerve, possibly caused by high frequency stimulation.

Stress Distribution at Hip Joint During Level Walking

In 1950, Bressler and Frankel [1] calculated dynamic hip joint force for the first time. Since then, researchers have reported the results obtained by various methods [2]. These methods are divided into two categories, based either on a mathematical model or on replacing the femoral head with a prosthesis. Of course the latter method is not universally acceptable. We adopted the model of Gilbert et al. [3], this being the simplest one, consisting of a system of two rigid segments and disregarding the change in center of pressure (COP) which moves from heel to toes. This model is acceptable under ideal special conditions in which only “bone to bone” force is calculated, that is, the pressure, based on the contraction of muscles which pass over joints, is disregarded. In other words, this model is suitable when there is ideally efficient walking with little contraction. Under this supposition, the force of the hip joint during level walking was calculated in the sagittal and frontal planes, using force platform, kinesiologic, and somatotype data for the stance phase. Two normals (a 29-year-old male; subject 1, and a 70-year-old female; 2) were examined in this study. Subject 1 walked rapidly and 2 walked slowly. We compared the components of the resultant force of the femoral head. In subject 1, the resultant force had a two-peak curve, the first peak reaching 2.7 times the body weight (bw); the second peak reached 2.2 times bw and the valley between the two peaks was 0.7 times bw. In subject 2, who had a slow gait, there was no finding of peaks as with subject 1, the shape being trapezoid; the maximal value was found in the latter half of the stance and was 0.88 times bw. In subject 1, the fore-aft components exceeded the vertical one, while in subject 2, the fore-aft component was larger than that of the ground reaction force, but did not exceed the vertical component at the femoral head. We depicted the stress distribution at the joint surface of the hip based on the calculated components, using a rigid body spring model (RBSM). Stress distribution was greatest posteriorly after heel contact; in the middle of the stance the stress to the vertical side was not so large. In subject 2, the stress was moderate in all phases of the stance. Since there is no way of verifying directly whether the three femoral components calculated above are acceptable, we attempted to verify these components indirectly, by comparing the vertical components calculated in the sagittal and frontal planes. In subject 1, the shape of the components was similar from heel contact to mid-stance, but suddenly after mid-stance the components in the sagittal plane decreased. In subject 2, the shape of the components was similar in all phases of the stance. Our findings could be useful for determining stress distribution at the intact hip joint surface of healthy subjects during level walking at a slow speed. However, in the latter half of the stance phase, with rapid walking, a more complete model, particularly in regard to the foot, would be preferable.

Biomechanical Analysis of the Dysplastic Hip: Pre- and Post-Pelvic and Femoral Osteotomy

Biomechanical analysis of the hip joint, using the rigid body spring model (RBSM) was performed to investigate the mechanism responsible for the progression of coxarthrosis and to obtain guidelines for treatment. As dysplastic change progressed, the abductor muscle strength required for one leg standing increased, as did pelvic displacement. After Chiari’s operation, pelvic displacement decreased remarkably, while more abductor muscle strength was required, due to the verticalization of the abductor muscle and the shortening of its lever arm. Varus osteotomy appeared to preserve the efficiency of abductor muscle strength by lengthening its lever arm. Clinically, in all patients, pain was either relieved or disappeared as a result of the muscle strengthening exercises having been done. When the practical abductor muscle strength was reduced to 50%–70% of the theoretical value calculated with the RBSM, hip pain score was about 20 points. Thus, by assessing the muscle strength both practically and theoretically, in addition to making an X-ray diagnosis, we were able to select a suitable treatment plan for patients with dysplastic hips.

Histological Study of Acetabular Clear Zone after Acetabular Reaming for Hip Arthoplasty using an Alumina Ceramic Endoprosthesis and a Metal One

ABSTRACT We have performed reconstruction of the hip following osteoarthritis by alumina ceramic bipolar hip prosthesis. We placed specially prepared alumina ceramic and metal heads in the femur to contact the acetabulum of beagle dogs, after the articular cartilage had been removed completely by reaming and bone marrow exposed. Radiographically, one month after the surgery, a well defined clear zone appearsed between acetabulum and prosthetic head, and three months following the surgery, the reamed acetabulum was completely reshaped and the clear zone became more apparent. In the clear zone, histological study showed changes from granulation tissue at early stage to matured fibrous connective tissue both in alumina ceramic and metal heads, and showed absorption and osteogenic response of the trabeculae in the bone marrow. The metal head formed loose connective tissue with many gaps whereas the ceramic one produced close stable tissue one year after surgery. The ceramic head was better finished for roundness and surface roughness than the metal one and was no changes at periods at 1 and 6 months post operation. Therefore we concluded the alumina ceramic was better material for an endoprosthetic head than Cr-Co-Mo alloy.