Peter S. Walker

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The roentgenographic parameters of motion in normal and abnormal shoulders, including the movement of the scapula, arm angle, glenohumeral angle, scapulothoracic angle, excursion of the humeral head, and instant center of motion for abduction in the plane of the scapula, were determined in twelve normal subjects and fifteen patients. The scapula rotated(More)
We have made a retrospective study of 1001 custom-made prostheses used as replacements after surgery for bone tumours. There were 493 distal femoral, 263 proximal femoral and 245 proximal tibial prostheses. Aseptic loosening was shown to be the principal mode of failure of the implants, and 71 patients had revision for aseptic loosening of a cemented(More)
We have performed endoprosthetic replacement after resection of tumours of the proximal tibia on 151 patients over a period of 20 years. During this period limb-salvage surgery was achieved in 88% of patients with tumours of the proximal tibia. Both the implant and the operative technique have been gradually modified in order to reduce complications. An(More)
This study was designed to determine the influence of laxity on clinical function after knee replacement. Using a recently developed computerized method, anteroposterior laxities were measured in 29 Insall-Burstein posterior stabilized, 25 Kinemax Condylar (posterior cruciate retaining), and 10 Oxford bicompartmental (anterior and posterior cruciate(More)
Knee specimens were placed in an apparatus which imposed cyclic anterior-posterior or rotatory forces, with various compressive loads applied to the joint. Force-displacement graphs or torque-rotation graphs were automatically plotted, giving the laxity under various conditions. The ligaments, capsule, and menisci provided joint stability under no-load(More)
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(More)
The purpose of this study was to determine the forces in the glenohumeral joint for isometric abduction (including all directions of rotation) in the plane of the scapula. The lines of actions of muscles were obtained from 3 upper quarter specimens, electromyographic data was used, as well as geometrical parameters of shoulder motion. The main assumption(More)
A stylized wedge-shaped defect was created in the medial plateau of autopsy specimens of the tibia to evaluate methods for fixation in total knee arthroplasty. A series of tibial components was inserted by five different methods. With each method loading of up to 1780 N axially and a varus load of 1340 N at 28 Newton-meters were assessed. The vertical(More)
Using intact fresh specimens, the cruciate ligament lengths for positions of flexion and internal-external rotation were computed using a non-invasive technique; using photographic methods, the centers of transverse rotation on the tibia and the direction of the flexion axis were also obtained. The anterior cruciate was found to be particularly effective in(More)
Forty failed hinged arthroplasties of the knee were revised by the insertion of another hinged implant. In 14 cases the prosthesis used at the revision operation was similar to the primary implant; in 26, a hinge with an elongated femoral stem was used, usually replacing part of the femoral shaft. In seven of these knees an elongated tibial stem was also(More)