M.L. Van der Linden

Effect of foot orthoses on the kinematics and kinetics of normal walking gait

Despite their wide clinical application and success, our understanding of the biomechanical effects of foot orthoses is relatively limited. The aim of this study was to assess the effect of medially wedged and laterally wedged foot orthoses on the kinematics and joint moments of the rearfoot complex, knee, hip and pelvis and the ground reaction forces. The principal effect of the foot orthoses was on the rearfoot complex, where significant changes in joint rotations and moments were observed. Medially wedged orthoses decreased rearfoot pronation and increased the laterally directed ground reaction force during the contact phase, suggesting reduced shock attenuation. The laterally wedged orthoses increased rearfoot pronation and decreased the laterally directed ground reaction force during the contact phase, suggesting increased shock attenuation. The effects of the orthoses on knee, hip and pelvis kinematics were generally minimal. In view of the minimal effect the orthoses had on joints proximal to the foot, it is suggested that the orthoses may have additional effects on the passive and active soft tissues of the lower limb and it is these changes that result in the documented clinical success.

A prospective randomised double-blind study of functional outcome and range of flexion following total knee replacement with the NexGen standard and high flexion components

Modifications in the design of knee replacements have been proposed in order to maximise flexion. We performed a prospective double-blind randomised controlled trial to compare the functional outcome, including maximum knee flexion, in patients receiving either a standard or a high flexion version of the NexGen legacy posterior stabilised total knee replacement. A total of 56 patients, half of whom received each design, were assessed pre-operatively and at one year after operation using knee scores and analysis of range of movement using electrogoniometry. For both implant designs there was a significant improvement in the function component of the knee scores (p < 0.001) and the maximum range of flexion when walking on the level, ascending and descending a slope or stairs (all p < 0.001), squatting (p = 0.020) and stepping into a bath (p = 0.024). There was no significant difference in outcome, including the maximum knee flexion, between patients receiving the standard and high flexion designs of this implant.

Proprioception and muscle torque deficits in children with hypermobility syndrome

OBJECTIVES Sensorimotor deficits such as impaired joint proprioception and muscle weakness have been found in association with hypermobility syndrome (HMS) in adults. HMS is more common in children than adults, yet such deficits have not been adequately investigated in paediatric populations. It is therefore uncertain as to what sensorimotor deficits are present in children with HMS. This study investigated knee joint proprioception and muscle torque in healthy children and those with HMS. METHODS Thirty-seven healthy children (mean age +/- s.d. = 11.5 +/- 2.6 yrs) and 29 children with HMS (mean age +/- s.d. = 11.9 +/- 1.8 yrs) participated in this study. Knee joint kinaesthesia (JK) and joint position sense (JPS) were measured, with the absolute angular error (AAE) calculated as the absolute difference between the target and perceived angles. Knee extensor and flexor muscle torque was assessed and normalized to body mass. Mann-Whitney U-tests were performed to compare JK, JPS and muscle torque between the two groups. RESULTS Children with HMS had significantly poorer JK and JPS compared with the controls (both P < 0.001). Knee extensor and flexor muscle torque was also significantly reduced (both P < 0.001) in children with HMS compared with their healthy counterparts. CONCLUSIONS The findings of this study demonstrated that knee joint proprioception was impaired in children with HMS. They also had weaker knee extensor and flexor muscles than healthy controls. Clinicians should be aware of these identified deficits in children with HMS, and a programme of proprioceptive training and muscle strengthening may be indicated.

Does a mobile-bearing, high-flexion design increase knee flexion after total knee replacement?

This prospective randomised controlled double-blind trial compared two types of PFC Sigma total knee replacement (TKR), differing in three design features aimed at improving flexion. The outcome of a standard fixed-bearing posterior cruciate ligament-preserving design (FB-S) was compared with that of a high-flexion rotating-platform posterior-stabilised design (RP-F) at one year after TKR. The study group of 77 patients with osteoarthritis of the knee comprised 37 men and 40 women, with a mean age of 69 years (44.9 to 84.9). The patients were randomly allocated either to the FB-S or the RP-F group and assessed pre-operatively and at one year post-operatively. The mean post-operative non-weight-bearing flexion was 107° (95% confidence interval (CI) 104° to 110°)) for the FB-S group and 113° (95% CI 109° to 117°) for the RP-F group, and this difference was statistically significant (p = 0.032). However, weight-bearing range of movement during both level walking and ascending a slope as measured during flexible electrogoniometry was a mean of 4° lower in the RP-F group than in the FB-S group, with 58° (95% CI 56° to 60°) versus 54° (95% CI 51° to 57°) for level walking (p = 0.019) and 56° (95% CI 54° to 58°) versus 52° (95% CI 48° to 56°) for ascending a slope (p = 0.044). Further, the mean post-operative pain score of the Western Ontario and McMaster Universities Osteoarthritis Index was significantly higher in the RP-F group (2.5 (95% CI 1.5 to 3.5) versus 4.2 (95% CI 2.9 to 5.5), p = 0.043). Although the RP-F group achieved higher non-weight-bearing knee flexion, patients in this group did not use this during activities of daily living and reported more pain one year after surgery.

Between-day repeatability of knee kinematics during functional tasks recorded using flexible electrogoniometry

The objective of this study was to assess the between-day repeatability of knee kinematics during activities of daily living recorded by electrogoniometry. One rater assessed the peak knee angles and knee excursion of 15 subjects during 13 activities twice with an average of 22 days (range 5-31) between the two assessments. The 15 subjects included four patients one year after total knee replacement (TKR) surgery, five patients before TKR surgery and six age-matched controls. Intra-class correlation coefficients and Bland and Altman coefficient of repeatability were derived to analyse the results. Only the most affected leg of the patients and the right leg of the controls were used for analysis. Different measures of repeatability showed different results. Intra-class correlation coefficients were higher than 0.75 for peak values of all functions except sitting down and rising from a standard chair. However, coefficients of repeatability ranged from 5.6 degrees for the loading response in level walking to 39.8 degrees for stepping out of a bath. Both of these values are higher than clinically significant changes seen after total knee surgery. It was concluded that for a single assessment on individual patients, the functional knee motion as performed in this study did not have sufficient repeatability. However, if the measurements are used to assess the average changes before and after surgery in a group of patients, the assessment of knee motion during activities such as level walking, and slope and stair ascending and descending were found to be sufficiently repeatable.

Repeatability of joint proprioception and muscle torque assessment in healthy children and in children diagnosed with hypermobility syndrome

BACKGROUND Impairment of joint proprioception in patients with hypermobility syndrome (HMS) has been well documented. Both joint proprioception and muscle torque are commonly assessed in patients with musculoskeletal complaints. It is unknown, however, if these measures change significantly on repeated application in healthy children and in children with HMS. AIM To investigate the between-days repeatability of joint proprioception and muscle torque in these groups. METHODS Twenty children (10 healthy and 10 with HMS), aged eight to 15 years, were assessed on two separate occasions (one week apart) for joint kinaesthesia (JK), joint position sense (JPS), and the extensor and knee flexor muscle torque of the knee. JK was measured using threshold to detection of passive movement. JPS was measured using the absolute angular error (AAE; the absolute difference between the target and perceived angles). Knee extensor and flexor muscle torque was normalized to body weight. RESULTS Intra-class correlation coefficients (ICC) for JK, extensor and flexor muscle torque were excellent in both groups (range 0.83 to 0.98). However, ICC values for JPS tests were poor to moderate in the two groups (range 0.18 to 0.56). 95% limits of agreement (LOA) were narrow in both cohorts for JK and muscle torque (indicating low systematic error) but wide for the JPS tests. 95% LOA also demonstrated that the measuring instruments used in this study had low between-days systematic error. CONCLUSIONS Based on ICC and 95% LOA, the repeatability of JK and muscle torque measurements was excellent in both healthy children and those with HMS. The JPS test can only be assessed with poor to moderate repeatability. The use of the JPS test in these children should be undertaken with caution.

Pain and quality of life perception in children with hypermobility syndrome

Background: Juvenile idiopathic arthritis runs an unpredictable course. Childrenwith oligoarticular disease may respond well to intra-articular steroids or haverecurrent episodes of synovitis. Children with polyarticular disease may respond toMethotrexate or require steroids and/or biologics. Currently there are no reliablepredictors of outcome in early disease, which leads to sub-optimal treatment.Methods: We are currently undertaking a five-year prospective study of childrenwith newly diagnosed and untreated JIA. All have knee involvement. At outset,we obtain synovial biopsies (N¼5) under ultrasound guidance. We then recorddetailed clinical, functional, radiological and laboratory data every 3/12 for twoyears. We are correlating outcomes at one and two years with synovial findingsrecorded at outset. Here we report on those children whom to date we havefollowed for one year.Results: Of the first 30 children, 18 had oligoarticular disease. Their diseaseactivity score fell from a mean of 3.54 to 1.12 at one year. Ten had a single episodeof swelling of the index joint while eight had 2 or more episodes.Twelve had polyarticular disease. All but two were improved at one year.The mean ESR fell from 44 to 13, and CRP from 33 to 5. Haemoglobin rose froma mean of 10.6 mg/dl to 12.5 mg/dl. The CHAQ improved in all but two.We found significantly more synovial pathology in the poly compared with oligopatients, with mean vessel score 6.9 vs. 2.6 (p<0.05) and mean B-cell score1.7 vs. 1.0 (p<0.05).On average, the oligo and polyarticular groups shared a similar degree ofsynovial hyperplasia and a comparable macrophage distribution. The CD3þ cells(mean 1.7 (0.8–2.7)) were predominately CD4þ (mean 1.7 (0.7–2.6)) anddistributed mainly within the sub-lining layer (SLL).However, we observed significant differences between patients within clinicalsubgroups.Conclusions: Almost 50% of oligoarticular patients had recurrent knee swelling,despite treatment. And while the majority of poly JIA responded to Methotrexate,a significant minority still required steroids or were already on biologics at one year.Infiltrates varied widely between patients; and we predict that synovial pathology,particularly vascularity and B-cell infiltrates, will correlate with a poor outcome andinadequate response to treatment.We will therefore analyse whether synovial findings can predict outcome foreach patient.

Preoperative predictors of knee range of motion during stair walking after total knee replacement

Summary: Hierarchical Multiple Regression was performed on the pre and postoperative measures of 56 patients with end-stage osteoarthritis. Post-operative range of knee motion during stair ascent and descent was predicted by pre-operative measures in different domain blocks. Conclusions: Pre-operative variables predicting post-operative stair walking differ between stair ascent and descent. This has consequences for the treatment of patients waiting for a total knee replacement.