Knee prostheses--one step forward, two steps back.
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Biomedical subjects
Publications and source records attributed to J Goodfellow.
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Three hundred one unconstrained meniscal arthroplasties were observed for as long as nine years, during which time 25 (8.3%) failed. Risk factors were sought by comparing the distributions of several preoperative variables in the group that failed with the group that was successful. Age, weight, the magnitude or direction of preoperative deformity, and the presence of postoperative malalignment were all without effect on the outcome of the operations. Knees with rheumatoid arthritis had a 95% survival rate at six years. Knees with osteoarthrosis had an equivalent survival rate of 83%. Knees in which the anterior cruciate ligament (ACL) was normal had a survival rate of 95% at six years; those in which the ligament was damaged or absent had an equivalent survival rate of 81%. Successful reconstruction of a knee with an unconstrained meniscal implant requires the presence and the preservation of an intact ACL.
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Thirty-two patients who underwent bilateral bicompartmental Oxford Meniscal Knee arthroplasty have been followed up prospectively for a mean period of 51 months from the time of their first operation. Pain relief was obtained in all but one knee; walking ability was improved in more than two-thirds. Overall patient satisfaction with the results was good. Two knees failed. The results demonstrate that bilateral knee arthroplasty can be expected to give good functional results.
The mechanisms controlling and limiting movement and serving to transmit load between the femur and the tibia are discussed. Having accounted for the transmission of all components of force and couple across the joint and noted the load-bearing role of the menisci, some principles which might guide the design of knee prostheses are deduced. It is shown that current designs transgress some of these principles. An experimental prosthesis is then described, which incorporates analogues of the natural menisci. The possible practical application of this novel principle has been studied in cadaveric human joints and in living patients.
Congenital spinal extradural cysts are rare and may be the cause of acute paraplegia. In their clinical features they closely resemble acute transverse myelitis. Immediate decompression of the spinal cord and removal of the cyst may lead to restoration of normal function. Myelography differentiates these two conditions by showing a cyst in communication with the spinal canal. This investigation must be mandatory.
The paper reports an experimental investigation into the mechanisms whereby the joints of living animals maintain their precise contours. The normal patter of joint incongruity in the rabbit's hip having first been established, three groups of experimental animals underwent operative procedures designed to reduce the joint pressure to a level unrealistic in normal life. In one group the hip was dislocated by manipulation; in a second group the muscles around the hip joint were divided; and in a third group the hind limb was disarticulated through the knee. When the animals were killed at intervals of a few weeks after the operations the experimental hip joint showed increased congruity in all cases. It is concluded that in immature animals there is a mechanism in joints to control the modelling of their shapes towards an ideal incongruity, and that that mechanisms is pressure sensitive.
Cadaver knee joints were mounted so that life-like forces of weight-bearing were simulated. The patello-femoral contact areas were defined under load throughout the range of movement by the dye method. During movement from extension to 90 degrees of flexion a band of contact sweeps across the patella from inferior to superior pole, but the odd facet makes no contact. At about 135 degrees of flexion separate medial and lateral contact areas form, the medial one limited to the odd facet. From extension to 90 degrees of flexion the patella holds the quadriceps tendon away from the femur, but in further degrees of flexion an extensive "tendo-femoral" contact area forms. Between 90 degrees and 135 degrees of flexion the patella rotates and the ridge between the medial and odd facets engages the femoral condyle. The odd facet is shown to be a habitual non-contact area and the ridge to be subject to high load, observations which correlate with cartilage lesions described in Part 2 of the paper.
Two distinct lesions affect the articular cartilage of the patella. Surface degeneration occurs particularly on the odd facet; it is age dependent, often present in youth and it becomes more frequent with increasing age. It probably does not occasion patello-femoral pain in youth, but may predispose to degenerative arthritis in that joint in later years and is regarded as a consequence of habitual disuse. The term "basal degeneration" is used to describe a lesion in which there is a fasciculation of collagen in the middle and deep zones of cartilage without, at first, affecting the surface. It was found astride the ridge separating the medial from the odd facet in twenty-three adolescents who had complained of prolonged patello-femoral pain. They were treated by excision of the disc of affected cartilage, with relief of pain in most cases. The pathogenesis of basal degeneration is related to the functional anatomy of the patella.
A case is reported of spontaneous subluxation of C.3 on C.4 in a 6-year-old boy due to an upper respiratory infection after surgical treatment for muscular torticollis.
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A patient-recorded home blood pressure series using an electronic manometer is used increasingly to provide a representative sample of blood pressure (BP) and to avoid frequent office visits and office rises in BP. Few of the many available electronic manometers have undergone rigorous testing and validation against a standard mercury manometer. We have evaluated fully the commonly used Philips 5306B electronic manometer against a Hawksley random zero mercury manometer employing a randomized, single-blind, crossover design and statistical analyses that have been validated previously. Although correlation coefficients greater than 0.9 were achieved for both systolic and diastolic pressure, the electronic manometer gave systolic and diastolic readings that differed from the mercury manometer by greater than or equal to +/- 5 mmHg in some 33% of patients and by greater than or equal to +/- 1- mmHg in some 18% of patients. Thus, in common with most electronic manometers, the Philips 5306B needs to be improved to correlate more closely with the standard mercury manometer to enhance its clinical usefulness.
Three cases of osteotomy for osteoarthritis of the hip which demonstrate the ability of cartilage to resurface previously eburnated areas are presented. These cases support the claim that cartilage regeneration of the femoral head after osteotomy does take place. Histologically, this new surface consists of fibrocartilage.