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Biomedical subjects

M Soudry

Publications and source records attributed to M Soudry.

71 records · Page 4Linked to original sources

Successive bilateral total knee replacement.

We studied the results of 304 posterior stabilized condylar knee arthroplasties, performed over a two and a half-year period, to compare unilateral, bilateral one-stage, and bilateral staged arthroplasty. The minimum length of clinical follow-up was two years. Using The Hospital for Special Surgery rating system, we found the clinical results to be identical for all three groups. The medical complications were similar in each group except that there was a higher incidence of thromboembolism and pulmonary embolism, as seen venographically, in the patients with staged procedures. We concluded that one-stage bilateral knee arthroplasty is preferable in a patient who requires replacement for severely arthritic knees.

Adult↗

Patellar dislocation following total knee replacement.

The reported incidence of patellar problems after total knee replacement has ranged from 5 to 30 per cent. Patellar dislocation is infrequent but can cause disabling symptoms. Between January 1974 and May 1982, eleven patients (twelve knees) with symptomatic lateral dislocation of the patella after total knee replacement were treated at The Hospital for Special Surgery by realignment of the extensor mechanism. All of the patients were women. Their average age was sixty-two years and average weight, eighty-seven kilograms. The diagnosis was osteoarthritis in seven knees and rheumatoid arthritis in five. Most of the patients had had preoperative valgus deformity (average, 18 degrees). The cause of dislocation was trauma in three knees, incorrect tracking of the patella after replacement in six, and malrotation of the tibial component in three. Four different prosthetic designs had been used. The design of the implant did not appear to be a factor causing dislocation in this group. The patellar dislocation was treated by proximal realignment of the quadriceps in ten knees, lateral retinacular release alone in one, and revision of the tibial and femoral components combined with proximal realignment in one. After an average follow-up of thirty-four months (range, twenty-four to fifty-seven months), the results according to The Hospital for Special Surgery knee-rating scale were excellent in ten knees and good in two, and there had been no redislocations.

Arthritis, Rheumatoid↗

Neuropraxis secondary to hemorrhage in a traumatic dislocation of the shoulder.

A case of traumatic shoulder dislocation associated with a tear of the subscapular artery is presented. The main clinical feature was a dramatic neurologic loss of the brachial plexus, reversed by exploration, evacuation of hematoma, and ligation of the bleeding vessel. Early surgical decompression to achieve neurologic recovery is emphasized.

Aged↗

Failure of total condylar knee replacement. Correlation of radiographic, clinical, and surgical findings.

The authors reviewed 55 failed total condylar knee replacements, correlating the radiographic and surgical findings at removal or revision. Failure was due to infection in 20 cases, mechanical loosening in 18, instability without loosening in 10, malalignment without loosening in 4, a supracondylar fracture in 2, and unknown causes in 1. In infection with loosening or chronic infection, radiographs usually showed a wide, extensive radiolucent region at the cement-bone interface around one or more components without shifting, while in acute infection without loosening the radiographs were normal. In mechanical loosening, in addition to a similar lucent region, the prosthesis became tilted in 16 out of 18 cases. Most loosening involved tilting of the tibial component into the varus position with subsidence into the medial tibial plateau, collapse of the cancellous bone, and plastic deformation. Radiographs can be helpful in determining the reason for failure of a total knee replacement, which is important in planning surgery.

Adult↗

Control of cement penetration in total knee arthroplasty.

A radiographic study of 45 knees immediately and at least two years after operation showed that the average depth of cement penetration was 1.5-3.0 mm at different locations around the interface and that there was a strong inverse relation between the development of radiolucency and initial cement penetration. In laboratory studies of penetration in the upper tibia, penetration was approximately proportional to bone pore diameter and to the square root of the applied pressure and inversely proportional to the time after initial mixing. There was a low correlation of the tensile strength of the cement-bone bond with the depth of penetration, probably due to the variability of the trabecular bone strength. Failure occurred by direct cement pullout or by partial or total fracture through the bone. In light of all factors, the suggested ideal depth of cement penetration is 3-4 mm. This penetration can be achieved by using the left-lift method about four minutes after initial cement mixing, but with some selective prepenetration around the periphery of the tibia.

Biomechanical Phenomena↗

[Forces at the implant-bone interface of condylar knee prosthesis--with special reference to the retention of the posterior cruciate ligament].

Breakdown of the implant-bone interface is the most important factor limiting the effective life of total joint replacement. A particular example is the tibial component of the knee prosthesis which interfaces with trabecular bone. It is postulated that one of the major reasons for interface breakdown is excessive shear, compressive and moment stresses at the implant-bone interface. These stresses can be greatly influenced by the design of the prostheses, namely surface contour of the tibial component and the retention of the posterior cruciate ligament. Forces across the tibial component-bone interface was measured for prostheses both retaining and sacrificing the posterior cruciate ligament and for partially conforming and non-conforming, flat geometries. The results are as follows: Shear force, normal force and moment force across the interface were significantly greater for the prostheses sacrificing the posterior cruciate ligament than for those retaining it. Moment force was markedly greater for the tibial component with anterior curvature than for flat tibial component. It was suggested from this experiment that the knee prosthesis should retain the posterior cruciate ligament and the surface of the tibial component should probably be flatter for reducing the forces at the implant-bone interface.

Biomechanical Phenomena↗

Effect of cane use on tibial strain and strain rates.

The effect of cane ambulation on hip biomechanics has been well studied, but its effect on tibial strains and strain rates is not known. To test the hypothesis that cane use may lower tibial strain and strain rates during walking, percutaneous axial extensometers were mounted on the right medial cortex of the midtibial diaphysis in seven male volunteers. In vivo peak-to-peak axial tibial strains and strain rates were measured for ipsilateral and contralateral cane usage and compared with a no cane control. Cane-assisted ambulation was not found to significantly lower strain magnitudes; however, tibial strain rates were significantly lowered by both ipsilateral and contralateral cane usage. We conclude that either ipsilateral or contralateral cane usage may be beneficial when lowering tibial strain rate is desired, such as in the treatment of tibia stress fracture or osteoarthrosis of the knee.

Adult↗

Role of physical activity training in attenuation of height loss through aging.

BACKGROUND: Although the genetic contribution to variability in bone mass has been estimated to be as high as 80%, evidence continues to accumulate suggesting that factors such as physical activity can influence bone mass which may avoid compression of the vertebrae leading to slower stature decline with age. OBJECTIVES: This study examines whether regular exercise has the potential of positively affecting the aging process with regard to height loss. METHODS: The height of 957 females and 1,088 males who were 35-55 years of age in 1965 were measured again in 1995. Based on a questionnaire, the subjects were divided into four groups. Group A (80 females, aged 73. 2 +/- 6 years, and 141 males, aged 72.1 +/- 5.7 years) represented subjects who were engaged in moderate vigorous aerobic activity throughout their lives; group B (95 females, aged 73.6 +/- 5.5 years, and 207 males, aged 71.7 +/- 6.1 years) were subjects who started their moderate vigorous aerobic activity around the age of 40 and kept their activity until the present time; group C (362 females, aged 73.2 +/- 5 years, and 390 males, aged 71.1 +/- 6 years) were persons who were active as young adults, but did not continue to exercise, and group D (425 females, aged 72.8 +/- 5.3 years, and 350 males, aged 70.9 +/- 6.1 years) were subjects who had not exercised regularly throughout their lives. RESULTS: All subjects lost height due to aging. However, significant (p < 0.05) differences in rate of height loss were found among the A, B, C, and D groups: for females 3.4 +/- 0.7, 3.5 +/- 0.8, 6.0 +/- 0.5, and 6.5 +/- 0.7 cm, respectively; for males 2.6 +/- 0.5, 3.1 +/- 0.4, 5.3 +/- 0.4, and 5. 5 +/- 0.5 cm, respectively. In addition, the females' height loss rate was significantly (p < 0.05) higher than that of the males in all four activity categories. CONCLUSIONS: These data suggest that lifelong moderate endurance training, especially after the age of 40 years, is associated with attenuation of height loss in both sexes. However, the magnitude of the attenuation is significantly higher in males.

Aged↗

Normal range of fetal knee movements.

Fetal limb movement abnormalities have been described to date in the literature only in subjective terms. The aim of the present study was to define objectively the normal range of fetal knee motion. The study population consisted of 240 normal fetuses at gestational age 16-39 weeks. The range of active knee motion was determined on routine prenatal ultrasound scans by measuring the angles between the midtibia, midfemur, and midknee on maximum flexion and extension. From 16 to 32 weeks, average knee flexion was 129.4 degrees (range, 120-140 degrees) and average extension was 23.7 degrees (range, 15-40 degrees). From 33 to 39 weeks, there was a gradual decrease in knee extension owing to lack of space in uterus. Knowledge of the normal range of fetal knee motion will assist clinicians in the prenatal diagnosis of neuromusculoskeletal disease.

Female↗

Musculoskeletal deformities in Behr syndrome.

SUMMARY: Seventeen children with Behr syndrome were investigated, focusing on the musculoskeletal deformities and long-term outcome. Behr syndrome is characterized by optic atrophy beginning in early childhood associated with ataxia, spasticity, mental retardation, and posterior column sensory loss. The ataxia, spasticity, and muscle contractures, mainly of the hip adductors, hamstrings, and soleus, are progressive and become more prominent in the second decade. In 70% of the patients, contractures developed in the lower limbs, requiring surgery mainly for the Achilles tendon, hamstrings, and adductor longus. At last follow-up at an average age of 21.7 years (range, 8-31 years), 13 of the patients are housebound walkers, 2 are nonfunctional walkers, and 2 are nonwalkers.

Achilles Tendon↗

Total knee arthroplasty.

The standard prosthesis for most arthritic conditions is a tricompartmental type. Patellar resurfacing should be done in most cases. The question of cruciate preservation or substitution is unresolved, and both types give equivalent clinical results. No advantage has been shown for left or right components. Correction of deformity occurs by soft-tissue release and ligament balancing, rather than by bone resection. Most primary replacements can be performed in this manner, but alignment is critical to the function and survival of a functioning arthroplasty. Most failures can be attributed to incorrect ligament balance or incorrect alignment. Cement fixation of the components has proved effective, and there is no immediate need for alternative methods such as bone ingrowth; new methods will have to prove themselves against the standard already established for cemented prostheses. Patellar complications such as fatigue fracture of the patellar bone now constitute the majority of problems following total knee arthroplasty.

Adult↗

The contribution of prenatal sonographic diagnosis of clubfoot to preventive medicine.

From 1995 through 1997, clubfoot was detected by transabdominal sonography in 13 fetuses of 12 women, in nine bilaterally and in four unilaterally (total, 22 clubfeet). The average menstrual age at diagnosis was 23.6 weeks (range, 17-36). Three fetuses had associated malformations: two were therapeutically aborted and one died 2 weeks after birth. Proper understanding of the significance of prenatal ultrasound findings of clubfoot will assist both the orthopaedist and the parents in reaching a decision concerning future management of their pregnancy.

Clubfoot↗

Below-knee plaster cast for the treatment of metatarsus adductus.

Sixty-five infants with moderate (37 feet) or severe (48 feet) inflexible metatarsus adductus were treated with a below-knee plaster cast. The deformity was corrected in 6-8 weeks in all cases. At the 2- to 6-year follow-up (mean, 4 years), the correction was maintained in all children who had had a moderate deformity; of the 44 feet with severe deformity that were available for examination, six now had a moderate deformity, and one a severe deformity. All forefeet were flexible, and further treatment was unnecessary. Our results are similar to those for above-knee plaster casts. We conclude that a below-knee plaster cast is effective in the treatment of metatarsus adductus.

Casts, Surgical↗