Abnormal loading and functional deficits are present in both limbs before and after unilateral knee arthroplasty.

Unilateral knee replacement is often followed by a contralateral replacement in time and the biomechanics of the other knee before and after knee replacement remains poorly understood. The aim of this paper is to distinguish the features of arthritic gait in the affected and unaffected legs relative to a normal population and to assess the objective recovery of gait function post-operatively, with the aim of defining patients at risk of poor post-operative function. Twenty patients with severe knee OA but no pain or deformity in any other lower limb joint were compared to twenty healthy subjects of the same age. Gait analysis was performed and quadriceps and hamstrings co-contraction was measured. Fifteen subjects returned 1year following knee arthroplasty. Moments and impulses were calculated, principal component analysis was used to analyse the waveforms and a classification technique (the Cardiff Classifier) was used to select the most discriminant data and define functional performance. Comparing pre-operative function to healthy function, classification accuracies for the affected and unaffected knees were 95% and 92.5% respectively. Post-operatively, the affected limb returned to the normal half of the classifier in 8 patients, and 7 of those patients returned to normal function in the unaffected limb. Recovery of normal gait could be correctly predicted 13 out of 15 times at the affected knee, and 12 out of 15 times at the unaffected knee based on pre-operative gait function. Focused rehabilitation prior to surgery may be beneficial to optimise outcomes and protect the other joints following knee arthroplasty.

Changes in gait which occur before and during the adolescent growth spurt in children treated by selective dorsal rhizotomy.

This paper presents long term follow up results from 17 children (6 girls, 11 boys, GMFCS levels II-IV), treated by means of selective dorsal rhizotomy (SDR). The particular focus is on the effect of the adolescent growth spurt on patients who had previously undergone SDR. The children were all assessed using 3D gait analysis, in combination with clinical examination at three time points-before SDR surgery (PRE), after SDR surgery when pre-adolescent (POST1) and post-adolescence (POST2). The total follow up period to POST2 was 8 years 6 months for girls and 9 years 5 months for boys. All children maintained or improved their GMFCS level. Positive changes in ranges of motion and gait were observed at POST1 and these were generally maintained over adolescence to POST2. The mean Gait Profile Score (GPS) had improved by 3.2 points (14.7-11.5) at POST1, with a non-significant deterioration of 0.3 over the adolescent growth spurt. These positive results reflect the total package of care for the children, involving careful pre-operative selection by a multidisciplinary team and post-operative management including intensive physiotherapy and maintenance in tuned ankle foot orthoses. Fifty-nine per cent of children had some additional orthopaedic surgery, mostly bony procedures. The overall benefits arising from their management need to be considered in the light of the likely deterioration experienced by this patient group. The results of this study support the use of SDR as part of a management strategy for carefully selected children with cerebral palsy with the aim of optimizing gait at skeletal maturity.

The effect of osteoarthritis of the knee on the biomechanics of other joints in the lower limbs.

The aim of this study was to examine the loading of the other joints of the lower limb in patients with unilateral osteoarthritis (OA) of the knee. We recruited 20 patients with no other symptoms or deformity in the lower limbs from a consecutive cohort of patients awaiting knee replacement. Gait analysis and electromyographic recordings were performed to determine moments at both knees and hips, and contraction patterns in the medial and lateral quadriceps and hamstrings bilaterally. The speed of gait was reduced in the group with OA compared with the controls, but there were only minor differences in stance times between the limbs. Patients with OA of the knee had significant increases in adduction moment impulse at both knees and the contralateral hip (adjusted p-values: affected knee: p < 0.01, unaffected knee p = 0.048, contralateral hip p = 0.03), and significantly increased muscular co-contraction bilaterally compared with controls (all comparisons for co-contraction, p < 0.01). The other major weight-bearing joints are at risk from abnormal biomechanics in patients with unilateral OA of the knee.

An investigation of the action of the hamstring muscles during standing in crouch using functional electrical stimulation (FES).

The hamstring muscle moment arms indicate that they act as hip extensors and knee flexors. Previous work using induced acceleration (IA) analysis and functional electrical stimulation (FES) has, however, revealed counter-intuitive muscle actions, particularly for biarticular muscles during the stance phase of normal gait. In conditions such as cerebral palsy the hamstrings have been associated with the development of pathological gait patterns, particularly crouch gait. This study examines the role of these muscles in the control of crouched standing postures. Five unimpaired adult subjects had their muscles stimulated during quiet standing in different degrees of crouch. Kinematic and kinetic changes were observed and measured using a 3D motion analysis system. The hamstring muscles were shown to act strongly to retrovert the pelvis and extend the hip. The action at the knee changes as crouch increases, moving from flexing to extending.