B B Seedhom

Forces during Squatting and Rising from a Deep Squat

The joint and muscle forces arising from and generated in the knee during the activity of squatting, and rising from a deep squat have been calculated. The analysis involved the consideration of a ...

Transmission of the Load in the Knee Joint with Special Reference to the Role of the Menisci Part I: Anatomy, Analysis and Apparatus

The menisci of the knee joint transmit a considerable fraction of the total load acting on the joint. This paper describes an investigation into the load carrying capacity of the individual meniscus. Interest is also directed to an examination of the function of the degenerate meniscus and that of the meniscus with different kinds of tears. Quantifying the meniscal loads is based on a four-spring model representing the load bearing areas in the knee with intact menisci. The assumptions underlying the model are discussed and the problems of loading associated with the four-spring model are described. These problems called for careful consideration of the methods of loading and aligning the joint. A loading machine with a special aligning device was built for the experimental work.The experimental procedure is described in Part II. The intact individual meniscus was shown to transmit 70-99 per cent of the load acting on the respective side. The load carrying capacity of the meniscus was shown to decrease fo...

Forces in the knee joint whilst rising from a seated position

Knee joint forces were determined by kinesiological techniques, using a high speed cine camera, a force platform, a specially constructed dynamometerized chair, and EMG recorders; so that a comparison could be made for rising from a normal chair with and without the aid of arms, and for rising from high and low chairs. For rising from the seated position, the knee joint forces parallel to the long axis of the tibia at the point of contact between the tibia and femur were found to be up to seven times body weight at about the time when the body left contact with the chair. When rising from a chair with the aid of arms, the knee joint forces were reduced to less than three times body weight. Knee joint and muscle forces were also reduced when rising from a high seat compared with rising from a low seat.

Wear of solid phase formed high density polyethylene in relation to the life of artificial hips and knees

Abstract Factors affecting the life of ultra high molecular weight high density polyethylene (HDPE) bearing components of artificial hips and knees are discussed A programme of wear tests is described and the results are discussed in relation to the life of the HDPE acetabular cup of hip protheses and the plastic component of the Leeds knee. Under favourable conditions of moulding, HDPE has very low wear rates. On the basis of the wear coefficient of the unmoulded material it was found that the reduction in the thickness of a Charnley type acetabulum was close to results obtained from in vivo measurements. It was estimated that the rate of reduction in the thickness of the plastic component of the Leeds knee prothesis would be less than one millimetre every twenty years, which is acceptable.

An Evaluation of the Ratio between the Tensions along the Quadriceps Tendon and the Patellar Ligament

An experiment was devised whereby physiological loads could be applied to the quadriceps tendon of cadaveric knee joints so that the ratio of tensions in the quadriceps tendon and the patellar ligament could be determined. On two knee joints, radiographs were taken before testing, so that the theoretical ratio of the tensions could be evaluated and compared with the experimental results. As the knee was flexed, the ratio of the tensions, frequently assumed to be unity, reduced by up to fifty per cent.

Biomechanics of the Patello-Femoral Joint. Part I: A Study of the Contact and the Congruity of the Patello-Femoral Compartment and Movement of the Patella

Techniques are described for studying the pattern of contact and congruence of the patello-femoral joint, and the movement of the patella at different angles of knee flexion. The study is carried out on cadaveric knee specimens.

Biomechanics of the Patello-Femoral Joint. Part II: A Study of the Effect of Simulated Femoro-Tibial Varus Deformity on the Congruity of the Patello-Femoral Compartment and Movement of the Patella

This paper investigates the effect of different degrees of varus deformity on the pattern of contact, congruence of the patello-femoral joint, and movement of the patella. Varus deformity of 5, 10, and 15 degrees was imposed on the same cadaveric knee specimen used in the study reported in Part I (Fujikawa, Seedhom, Wright, 1983). This was done by high tibial osteotomy and the introduction of a wooden wedge of the appropriate thickness to effect the deformity. It was found that the contact gradually shifted to the medial side of the knee, and the congruence of the patello-femoral compartment was gradually destroyed as the degree of varus deformity increased to 15 degrees, although the effect of 5 degrees of varus deformity was minimal.Clinically, contact is shifted to the lateral side of the knee with varus deformity, but this is invariably associated with lateral tibial rotation. This rotation explains the difference between the results of the varus deformity imposed on cadaveric knees and those observed...

A comparison of knee joint and muscle forces in women, 36 weeks pregnant and four weeks after delivery

Knee joint and muscle forces were determined for three women when they were 36 weeks pregnant and again four weeks after delivery, for the activity of rising from a seated position. The knee joint ...