Morrish, Gillian Mary; (1997) Chronic malfunction of the patellofemoral joint: The causal role of abnormalities of quadriceps action and poor tracking. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Malalignment of the patella has been implicated in patellofemoral problems, but the aetiology of the condition is not well understood. Efforts have been made in this thesis to study the underlying abnormalities, both biomechanical and of muscle function, which might contribute to this syndrome. The function of 72 patients with chronic anterior knee pain, where the onset has been insidious rather than a direct response to trauma, has been studied and compared with groups of normal subjects. Many of the experiments undertaken relate to the muscle activity, in the portions of the quadriceps thought to affect the position of the patella. The changes which have been seen, have then been correlated with other abnormalities, in order to understand their place in the pathology of this condition. Other experiments were done only with groups of normal subjects, and relate to the normal functioning of the quadriceps, in different conditions. Particular areas of study have been:- 1. Signs and symptoms have been recorded in the patient group, and correlated with other abnormalities seen. The intensity of pain and extent of disability have been recorded by means of a questionnaire given to each patient. 2. The quadriceps strength of both lower limbs has been assessed by means of a maximal voluntary extensor effort, isometrically performed, and compared with the predicted strength based on the height of the individual. 3. EMG activity of the oblique fibres of vastus medialis and vastus lateralis as well as rectus femoris, was compared with extensor force at different knee angles, isometrically, isokinetically, and dynamically. Evidence of reflex inhibition due to pain and other factors has been sought. Effort has been made to understand the changes in muscle activation of the patient group, by studying the quadriceps activation of a group of normal subjects in different knee positions and at different velocities. 4. The biomechanics of the whole of the lower limb has been studied at rest, by surface markings and range of movement of the various joints. The effect of this on the gait pattern has been studied by video recording of the patient group, as well as normal subjects. 5. A study of the position of the patella by computerised tomography, with respect to its articulation with the lower end of the femur, in a small group of patients and also with normal subjects. 6. A small group of patients was tested before and after 6 weeks of conservative treatment, in order to ascertain which parameters were capable of change. From the questionnaire, the changes noted were correlated with the extent of disability and intensity of pain. 7. A study of the normal anatomy of the joint in one cadaver has been made, so that the effects of the observed biomechanical factors could be more fully understood. Not only was there a considerable loss of quadriceps strength in the patient group, but the EMG studies showed abnormalities of quadriceps activation, which were particularly evident in the oblique fibres of the vasti. There were also differences in the alignment of the long lower limb bones in these individuals, which were not apparent in the normal subjects. Correlation among different results did not show direct correlation of one pathological finding with another. They suggest that this syndrome is multifactorial. The studies on normal subjects show that in some conditions, changes in rotatation of the hip and knee do alter the way in which the vasti are activated.

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