Biomedical subjects
J Goodfellow
Publications and source records attributed to J Goodfellow.
Characteristics of the Oxford knee. Basic concepts of surface replacements.
Mechanical and kinematic principles are very important in knee prostheses. The use of artificial menisci is the only way to provide a kinematically free range of motion with a wide area of load transfer. This allows polyethylene wear to be minimized. However, not only the design of the prosthesis, but also the patient's underlying disease must be paid more attention.
Medial unicompartmental arthroplasty. A survival study of the Oxford meniscal knee.
One hundred twenty-one knees with medial compartment osteoarthrosis were treated by unicompartmental arthroplasty with the Oxford Knee. The strict selection criteria were (1) the presence of a functioning anterior cruciate ligament, (2) fully correctable deformity, and (3) full thickness of articular cartilage in the lateral compartment. The mean elapsed time from surgery was 44.4 months. One knee has required revision for a loose tibial component. The results at this stage are as acceptable as those of tricompartmental knee arthroplasty and better than those of high tibial osteotomy.
Evidence for validity of a health status measure in assessing short term outcomes of cholecystectomy.
OBJECTIVE: To assess the validity of the Nottingham health profile (NHP) as an indicator of short term outcome of cholecystectomy. DESIGN: Prospective assessment of outcome. SETTING: One teaching hospital. Patients--161 consecutive patients admitted for cholecystectomy between January 1989 and September 1990. MAIN MEASURES: Patients' reported symptoms and self assessed NHP scores before cholecystectomy and at follow up at three and 12 months (76 patients); assessment before admission (19). RESULTS: Complete data were obtained preoperatively and at three months' follow up from 154 patients; seven did not respond to the follow up questionnaire. 76/84(90%) patients in the study 12 months or more answered the 12 month follow up questionnaire; eight did not respond. Significant changes in score before and at three months after the operation were observed for four of the six dimensions: energy (35.34 v 19.53, p < 0.0001), pain (27.38 v 9.8, p < 0.0001), sleep (26.99 v 17.51, p = 0.0002), and emotional reactions (16.12 v 7.56, p = 0.001). The mean scores for 76 patients followed up at three and 12 months showed little subsequent change. Scores in readmitted patients were all significantly higher, suggesting poor health. Patients with five reported symptoms had significantly worse scores for all dimensions. Scores were similar before cholecystectomy whether the questionnaire was completed before or after admission. CONCLUSION: The NHP is an appropriate tool for monitoring changes in health after cholecystectomy.
Knee prostheses--one step forward, two steps back.
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Malignancy and joint replacement.
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The anterior cruciate ligament in knee arthroplasty. A risk-factor with unconstrained meniscal prostheses.
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.
Orthopaedic robotics. Third Annual International Symposium on Custom-made Prostheses. October 1990--Nice, France.
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Bilateral Oxford Meniscal Knee arthroplasty.
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.
Fixation of the tibial components of the Oxford knee.
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Solvent effects and polar interactions in the structural stability and dynamics of globular proteins.
Using detailed hydrogen bonding, surface exposure, internal environment, and solvent interaction calculations on several proteins, in conjunction wit data from quantum mechanical hydrogen-bonding studies, various contributions to the free energy of globular estimated and their likely relative significance discussed. A picture emerges of globular proteins as extremely well-fitting jigsaw-puzzles, in which no single driving force dominates the marginal stability of the native conformation. Rather, the folded structure is seen as the result of a complex global maximization of several strongly-interacting driving forces. In particular, the necessity to maintain very efficient internal hydrogen-bonding, and the role of the solvent as a hydrogen-bond sink, are stressed as strong constraints on the (incomplete) maximization of hydrophobic effects. The possible significance of internal dipole-induced dipole interactions is discussed tentatively. Although quantitative estimates of the various contributions remain uncertain, consideration of effective force constants suggests that polar, including solvent, interactions may largely determine the overall curvatures of the native conformation's potential well, and be important in controlling the flexibility of local regions which are important for the exact positioning of groups during enzyme catalysis, as well as the molecule's overall dynamics. In contrast, hydrophobic interactions change less for small geometrical perturbations, and seem more relevant to directing the folding protein. along a path to a region in configurational space where the polar interactions can switch on for the final "docking".
He who hesitates is saved.
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The mechanics of the knee and prosthesis design.
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 cyst (lateral meningocele) simulating acute transverse myelitis. Report of a case.
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.
Joint surface incongruity and its maintenance: an experimental study.
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.
Patello-femoral joint mechanics and pathology. 1. Functional anatomy of the patello-femoral joint.
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.
Patello-femoral joint mechanics and pathology. 2. Chondromalacia patellae.
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.
An unusual case of subluxation of C.3-C.4.
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.