Roland Zügner

Outcome after total hip arthroplasty: Part II. Disease-specific follow-up and the Swedish National Total Hip Arthroplasty Register

The Swedish National Total Hip Arthroplasty Register records primary hip replacements, revisions and surgical technique/environmental factors. The end-point for failure is revision. A prosthesis still in place, however, does not mean success. Clinical and radiographic outcomes should describe in more detail the efficacy of hip replacement surgery instead of the relatively blunt outcome measure that the register can provide. We performed a clinical outcome analysis on patients with primary total hip replacement thus testing the adequacy of the end-point for failure in the Swedish register. 1,113 randomly selected patients who had had total hip replacement surgery between 1986 and 1995 answered a diseasespecific self-administered questionnaire (WOMAC). A cohort of 344 patients was studied, using the Harris Hip Score and a conventional radiographic examination as outcome measures. We found clinical failure rates of 13% and 20% for all implants after 10 years, using 60 points or revision as the definition of failure in the Harris Hip Score and WOMAC, respectively. The result, according to the register during the same period, was a 7% revision rate. The clinical failure rate depended on the type of evaluation tool, definition of failure and demographics, which made it difficult to decide whether there was a need for revision. With the exception of pain measured by the Harris Hip Score, the results showed no significant correlation between clinical failure and radiographic failure. Hence, with the knowledge that there is a difference between the revision rate according to the register and clinical outcome, the strict definition of failure in the register is useful as an end-point for primary hip replacement surgery.

Muscle strength training to improve gait function in children with cerebral palsy

The aim of the study was to investigate the influence of muscle strength training on gait outcomes in children with cerebral palsy. Sixteen children (two females, 14 males, Gross Motor Function Classification System levels I–II, mean age 12y 6mo, range 9y 4mo–15y 4mo) underwent muscle strength measurement using a handheld device, Gross Motor Function Measure (GMFM) assessment, three‐dimensional gait analysis, joint range of motion assessment, and grading of spasticity before and after 8 weeks of training. All participants had a diagnosis of spastic diplegia and could walk without aids. Training consisted of exercises for lower extremity muscles with free weights, rubber bands, and body weight for resistance, three times a week. Values for muscle strength below normal were identified in all children; this was most pronounced at the ankle, followed by the hip muscles. After training, muscle strength and GMFM scores increased, velocity was unchanged, stride length increased, and cadence was reduced. There was an increase in hip extensor moment and power generated at push off. Eight weeks of muscle strength training can increase muscle strength and improve gait function.

Changed gait pattern in patients with total knee arthroplasty but minimal influence of tibial insert design: gait analysis during level walking in 39 TKR patients and 18 healthy controls.

Introduction Previous radiostereometric studies have revealed abnormal anterior-posterior translation of the femur in patients operated with AMK (DePuy, Johnson and Johnson, Leeds, UK) total knee arthroplasty (TKA). Based on these observations, we hypothesized that patients with TKA have an abnormal gait pattern, and that there are differences in kinematics depending on the design of the tibial joint area. Method We used a gait analysis system to evaluate the influence of joint area design on the kinematics of the hip and knee during level walking. 39 TKA patients (42 knees) and 18 healthy age-matched controls were studied. Patients with 5° varus/valgus alignment or less were randomized to receive either a relatively flat or a concave tibial insert with retention of the posterior cruciate ligament. Patients who had more than 5° varus-valgus alignment and/or extension defect of 10° or more were randomized to receive the concave or a posterior-stabilized tibial component with resection of the posterior cruciate ligament. Results Patients with TKA tended to have less hip and knee extension and decreased knee and hip extension moment than controls. They also tended to walk more slowly. TKA altered the gait pattern, but choice of implant design had little influence. Interpretation In patients with a similar degree of degenerative joint disease and within the limits of the constraints offered by the prostheses under study, the choice of joint area constraint has little influence on the gait pattern.

Improvements in hip- and pelvic motion for patients with osseointegrated trans-femoral prostheses

This study describes the changes in hip and pelvic kinematics in 19 trans-femoral amputees, who were treated with an osseointegrated trans-femoral prosthesis. Patients were studied with 3-dimensional gait analysis, walking with socket prosthesis within two days before the osseointergration procedure. The post-operative gait analysis was carried out at the 2 year follow-up visit. Fifty-seven; age-, side- and gender-matched healthy subjects served as controls. Post-operative data showed that patients who had an osseointegrated transfemoral prosthesis increased their hip extension by 7.3° (p=0.007), changing from -2.6° (range -13.4° to 10.7°) to -9.9° (range -29.4° to 5°). Moreover, the pre-operative anterior pelvic tilt was reduced by 4.0° (p=0.016), changing from 21.7° (range 11.9-34.8°) to 17.7° (range 5.5-25.7°). Values for hip extension and pelvic tilt changed toward those of controls. These results confirm that patients treated with osseointegrated trans-femoral prosthesis encounter significant changes of their kinematic pattern in terms of hip extension and anterior pelvic tilt. Even though the changes were moderate they may, in the long-term have a positive influence on low-back biomechanics and could contribute to reducing the risk of further problems with low back pain.

Total knee replacement influences both knee and hip joint kinematics during stair climbing

A gait analysis system was used to evaluate the kinematics of the hip and knee during stair ascending and descending after operation with total knee replacement. Patients with 5° varus/valgus alignment or less were selected randomly to receive either a flat or a concave tibial component with retention of the posterior cruciate ligament. Patients who had more than 5° varus/valgus alignment and/or an extension defect of 10° or more were selected randomly to receive the concave or posterior-stabilized tibial component with resection of the posterior cruciate ligament. Twenty patients and 17 controls were studied 1–2 years after the operation. Patients had abnormal kinematics during stair ascending and descending. Both knee extension and flexion were reduced. Hip extension tended to decrease, and decreased hip extension moment was noted.RésuméUn system d’analyse de la marche a été utilisé pour évaluer la cinématique de la hanche et du genou pendant la montée et la descente d’escalier après prothèse totale du genou. Les malades avec 5° ou moins de varus/valgus ou moins ont été randomisés pour recevoir un composant tibial plat ou concave avec conservation du ligament croisé postérieur. Les malades qui avaient plus de 5° de varus/valgus et/ou un défaut d’extension de 10° ou plus ont été randomisés pour recevoir un composant tibial concave ou un composant postéro-stabilisé avec résection du ligament croisé postérieur. Vingt et un malades et 17 contrôles ont été étudiés une à deux années après l’opération. Les malades avaient une cinématique anormale pendant la montée et la descente l’escalier. L’extension et flexion du genou étaient plus faibles. L’extension de la hanche avait tendance à diminuer et une augmentation du moment de flexion a été noté.

Simultaneous measurements of knee motion using an optical tracking system and radiostereometric analysis (RSA)

Background and purpose Invasive methods are more reproducible and accurate than non-invasive ones when it comes to recording knee kinematics, but they are usually less accessible and less safe, mainly due to risk of infection. For this reason, non-invasive methods with passive markers are widely used. With these methods, varying marker sets based on a number of single markers, or sets of markers, known as clusters, are used to track body segments. We compared one invasive method—radiostereometric analysis—with a non-invasive method, an optical tracking system with 15 skin-mounted markers. Methods 9 subjects (10 knees) were investigated simultaneously with a dynamic RSA system and a motion-capture system while performing an active knee extension. Results For flexion/extension, there was good agreement on an individual basis and at the group level. For internal/external rotation, the group mean was fairly similar, up to 25 degrees of flexion. Recordings of abductions and/or adductions revealed a systematic mean difference of 2–4 degrees during the range of flexion measured. The correlation between the 2 methods in the horizontal and frontal planes was poor. Interpretation Our skin-marker model provided reliable data for flexion/extension. Recordings of internal/external rotation and abduction/adduction were less accurate on an individual basis than at the group level, most probably due to soft-tissue motion and the presence of small true motion in these planes.

Reproducibility of the physiological cost index among individuals with a lower-limb amputation and healthy adults.

BACKGROUND AND PURPOSE The physiological cost index (PCI) is a clinical measurement used to estimate the energy cost of walking. The reproducibility of the PCI has been questioned and no study has investigated the measurement error among individuals with a lower-limb amputation. The aim was to investigate the test-retest reproducibility of the PCI in individuals with a lower-limb amputation and healthy adults. METHODS The study comprised 28 individuals (20 males, eight females, mean age 49 years) with a unilateral amputation due to reasons other than vascular disease and 31 healthy volunteers (20 males, 11 females, mean age 47 years). PCI values were obtained by registering heart rate at rest and during level indoor walking for 5 minutes at a comfortable speed. A within-day test-retest assessment was performed. Reproducibility analyses included intra-class correlation, analyses of systematic differences between measurements, calculation of the smallest detectable change (SDC) and coefficient of variation (CV), and the results were finally visualized using Bland-Altman plots. RESULTS The reliability in terms of intra-class correlation was excellent for both groups (0.966 and 0.948). In the amputee group, the PCI revealed a mean difference of 0.026 (p = 0.016) between tests (PCI = 0.555, standard deviation [SD] = 0.214 and PCI = 0.581, SD = 0.236, respectively). In the healthy group, there was no systematic difference between tests (PCI = 0.329, SD = 0.114 and PCI = 0.331, SD = 0.110, respectively). The SDC was 0.116 in the amputee group and 0.070 in the healthy group, giving a CV of 20.4% and 21.0%,respectively. CONCLUSIONS The within-day test-retest reproducibility of the PCI was excellent among individuals with lower-limb amputations and healthy adults in terms of intra-class correlation and acceptable in terms of agreement. The SDC, which was calculated for each group, should be considered when demonstrating an individual difference after an intervention.

Assessment of Gait Symmetry and Gait Normality Using Inertial Sensors: In-Lab and In-Situ Evaluation

Quantitative gait analysis is a powerful tool for the assessment of a number of physical and cognitive conditions. Unfortunately, the costs involved in providing in-lab 3D kinematic analysis to all ...

Foot deformities, function in the lower extremities, and plantar pressure in patients with diabetes at high risk to develop foot ulcers

Objective Foot deformities, neuropathy, and dysfunction in the lower extremities are known risk factors that increase plantar peak pressure (PP) and, as a result, the risk of developing foot ulcers in patients with diabetes. However, knowledge about the prevalence of these factors is still limited. The aim of the present study was to describe the prevalence of risk factors observed in patients with diabetes without foot ulcers and to explore possible connections between the risk factors and high plantar pressure. Patients and methods Patients diagnosed with type 1 (n=27) or type 2 (n=47) diabetes (mean age 60.0±15.0 years) were included in this cross-sectional study. Assessments included the registration of foot deformities; test of gross function at the hip, knee, and ankle joints; a stratification of the risk of developing foot ulcers according to the Swedish National Diabetes Register; a walking test; and self-reported questionnaires including the SF-36 health survey. In-shoe PP was measured in seven regions of interests on the sole of the foot using F-Scan®. An exploratory analysis of the association of risk factors with PP was performed. Results Neuropathy was present in 28 (38%), and 39 (53%) had callosities in the heel region. Low forefoot arch was present in 57 (77%). Gait-related parameters, such as the ability to walk on the forefoot or heel, were normal in all patients. Eighty percent had normal function at the hip and ankle joints. Gait velocity was 1.2±0.2 m/s. All patients were stratified to risk group 3. Hallux valgus and hallux rigidus were associated with an increase in the PP in the medial forefoot. A higher body mass index (BMI) was found to increase the PP at metatarsal heads 4 and 5. Pes planus was associated with a decrease in PP at metatarsal head 1. Neuropathy did not have a high association with PP. Conclusions This study identified several potential risk factors for the onset of diabetic foot ulcers (DFU). Hallux valgus and hallux rigidus appeared to increase the PP under the medial forefoot and a high BMI appeared to increase the PP under the lateral forefoot. There is a need to construct a simple, valid, and reliable assessment routine to detect potential risk factors for the onset of DFU.

Comparison of plantar pressure in three types of insole given to patients with diabetes at risk of developing foot ulcers – A two-year, randomized trial

Background Special insoles and shoes designed to prevent foot ulcers caused by repetitive high pressures are recommended for patients with diabetes who have any of the following risk factors: neuropathy; peripheral vascular disease; foot deformities; previous ulcers; amputation; and skin pathologies. However, there is a need for increased knowledge regarding: a) differences in the peak pressure (PP) and pressure time integral (PTI) for different types of insoles; and b) the properties of the pressure distribution for insoles used over a period of several months. We present the results of a randomized trial to compare the plantar pressures of three commonly used insoles. Objectives The primary objective was to compare the PP and PTI between three types of insoles. The secondary objective was to explore the long-term pattern of peak plantar pressure distribution and variations in specific regions of interest (ROI). The tertiary objective was to investigate the impacts of insole adjustments, how much the insoles were used, and the levels of patient satisfaction. Methods In a 2-year trial, 114 patients with type 1 (N = 31) or type 2 (N = 83) diabetes (62 men and 52 women; mean age, 57.7 ± 15.4 years; duration of diabetes, 12.3 ± 11.2 years; neuropathy, 38%), were randomized to be supplied with one of three different insoles. The ethylene vinyl acetate (EVA) insoles were used in outdoor walking shoes. The 35 EVA group (N = 39) received soft custom-made insoles composed of EVA of 35 shore A hardness, the 55 EVA group (N = 37) received custom-made insoles composed of EVA of 55 shore hardness, and the control group (N = 38) received prefabricated insoles composed of a hard core with a top layer of soft 12 shore hardness microfiber. Using F-Scan®, the in-shoe plantar pressures were measured at seven ROI (hallux, metatarsal head 1, metatarsal head 2, metatarsal head 4, metatarsal head 5, lateral aspect of the mid-foot, heel) on five occasions during the study period. The plantar-pressure variables used were PP (main outcome) and PTI. The plantar patterns of load were explored, satisfaction and usage of the insoles were rated by the participants, and insole adjustments were recorded. Results A mixed model analysis estimated lower PP values in the heel regions for the 35 EVA and 55 EVA insoles (171 ± 13 and 161 ± 13 kPa, respectively) than for the prefabricated insoles (234 ± 10 kPa) (p < 0.001). Also for some of the other six ROI indications of difference in PP or PTI could be observed. The redistribution of peak plantar pressure for all of the insoles, was stable at the mid-foot, while the proportion of load on the distal area changed during the study period According to the self-reported answers (scale, 0–100), the average usage of the insoles was rated as 79 and satisfaction was rated as 85 (N = 75). Thirty-two percent of the subjects had not received foot care. Fourteen adjustments to insoles were made during the study period, and 86 pairs of insoles were exchanged due to wear, with 49% being exchanged in the 35 EVA group. Conclusions Custom-made insoles used in combination with stable walking shoes gave lower pressures at the heel region. The variation makes it difficult to detect a systematic difference in plantar pressure for the 6 ROI, if such a difference indeed exists. The levels of satisfaction and usage for all the insoles tested were high. The insoles maintained their pressure redistribution properties over long periods, and few adjustments were needed.