Quantitative evaluation of gait pattern in patients with osteoarthrosis of the knee before and after total knee arthroplasty. Gait analysis using a pressure measuring system

Verification of biomechanical factors of gait related to medial knee loading in patients 6 Months after total knee arthroplasty

Background

The knee adduction moment (KAM) is considered an index for estimating the knee mechanical load, and increased KAM peak and KAM impulse are related to increased medial knee load and progression of knee joint degeneration. We aimed to verify the biomechanical factors of gait related to medial knee loading in patients 6 months after TKA.

Methods

Thirty-nine women who underwent TKA were enrolled. A three-dimensional gait analysis was performed 6 months postoperatively to generate data on the lower limb joint angle, moment, and power at the backward component (braking phase) and forward component (propulsion phase) peaks of the ground reaction force. Medial knee loading was evaluated using the time-integrated value of KAM during the stance period (KAM impulse). The higher the value of the KAM impulse, the higher the medial knee joint load. The relationships between the KAM impulse and the data for biomechanical factors were evaluated using partial correlation analysis with gait speed as a control factor.

Results

In the braking phase, the KAM impulse positively correlated with the knee adduction angle (r = 0.377) and negatively correlated with the toe-out angle (r = -0.355). The KAM impulse positively correlated with the knee adduction angle (r = 0.402), the hip flexion moment (r = 0.335), and the hip adduction moment (r = 0.565) and negatively correlated with the toe-out angle (r = -0.357) in the propulsive phase.

Conclusion

The KAM impulse 6 months after TKA was related to the knee adduction angle, hip flexion moment, hip adduction moment, and toe-out angle. These findings may provide fundamental data for controlling variable medial knee joint load after TKA and implementing patient management strategies to ensure implant durability.

Kinematic Alignment May Reduce Opioid Consumption and Length of Stay Compared to Mechanically Aligned Total Knee Arthroplasty

OBJECTIVE

Previous studies have sought to determine the effects of total knee arthroplasty (TKA) using kinematic alignment (KA) versus mechanical alignment (MA) to reproduce the native knee alignment and soft tissue envelope for improved patient satisfaction. There are limited studies that compare acute perioperative outcomes between KA and MA patients as it pertains to pain-related opioid consumption and hospital length of stay (LOS). This study aims to compare early KA and MA in restoring function and rehabilitation after surgery to reduce hospitalization and opioid consumption.

METHODS

A retrospective review of 42 KA and 58 MA primary TKA patients performed by a single surgeon between 2020-2021 was conducted. Demographics were controlled between groups and radiographic measurements and functional outcomes were compared. Pain was evaluated with inpatient/outpatient morphine milligram equivalents (MME) and visual analogue scale (VAS) scores. Mobility was assessed using multiple measures by a physical therapist. Mean preoperative and 3-month postoperative flexion range of motion (ROM) were analyzed, and overall complications, LOS, and non-home discharge between groups compared. Continuous variables were compared using the Wilcoxon rank-sum test, and categorical variables were compared using the chi-square or Fisher exact test. Statistical significance was set at P < 0.05.

RESULTS

KA patients had shorter LOS (1.8 vs 3.1 days) and less cumulative opioid requirements compared to MA patients (578 vs 1253 MME). On postoperative day 0, KA patients ambulated on average twice the distance of MA patients (20 vs 6.5 feet). KA patients had residual tibia component in varus (1.4° vs -0.3°), femoral component in valgus (-1.9° vs 0.2°), and valgus joint line obliquity compared with MA (-1.5° vs 0.2°). There were no significant differences between 3-month postoperative flexion arc motion, discharge destination, KOOS or SF-12 outcomes, and surgical complication rates between groups.

CONCLUSIONS

By restoring the native joint line obliquity and minimizing the frequency of ligament releases, KA for TKA may improve pain relief, early mobility, and decreased length of stay compared with traditional methods of establishing neutral limb axis by MA.

Development of the center of pressure velocity in the healing process after intra-articular calcaneus fractures

BACKGROUND

Calcaneal fractures are among the most common foot injuries and sometimes develop manifold post-surgical complications. Restricted foot movement is one of the main functional limitations which often persists during long-term rehabilitation. Therefore, it is important to quantitatively monitor the biomechanical foot mobility after calcaneal fracture from an early stage in order to achieve an optimal therapeutic treatment.

RESEARCH QUESTION

Evaluation of the Center of Pressure velocity (v_COP) in patients after intrarticular calcaneal fractures during the healing progress from three to 24 months after surgery.

METHODS

A total of 20 patients with unilateral calcaneal fracture were investigated by means of pedobarography and marker-based gait analysis at three, six, 12 and 24 months after surgery. Data for v_COP [m/s], maximum external dorsal extension moments during stance (DEmoment_stance) and tibiotalar range of motion during mid stance (MS) and terminal stance (TS) were obtained. Functional evaluation was performed using clinical examination (e.g. calf circumference measurements) and patient-reported outcome measures (SF-36).

RESULTS

When compared to the healthy side, v_COP of the injured side showed a significant reduction during MS (3 months: 48%, p < 0.001; 6 months: 13%; p = 0.040) and an significant increase during TS (3 months: 110%, p < 0.001; 6 months: 43%, p < 0.001; 12 months: 17%, p = 0.012). DEmoment_stance of the fractured foot, showed a significant increase of 80% (p < 0.001) from three to 24 months after surgery, which correlated with v_COP at three and six months after surgery (p < 0.05; v_{COP MS:} 3 months: r = 0.876, 6 months: r = 0.685; v_{COP TS:} 3 months: r = -0.554, 6 months r = -0.626).

SIGNIFICANCE

v_COP might serve as an indicator for foot mobility and function during the early healing phase after calcaneal fractures. As v_COP can be obtained by pedobarography it is more readily accessible an less costly compared to foot function obtained by marker based gait analysis.

Spatiotemporal parameters of the operated and non-operated knees before and after unilateral total knee arthroplasty

BACKGROUND

Knee osteoarthritis is a common condition in various orthopedic clinics and hospitals. The aim of this study was to investigate the effects of unilateral total knee arthroplasty (TKA) application on short and long-term spatiotemporal gait parameters, maximum plantar pressure (MPP), and functional status in patients with knee osteoarthritis.

RESEARCH QUESTION

What is the change process in spatiotemporal parameters without any intervention before and after TKA surgery?

METHODS

This study is a prospective and cross-sectional study. Participants were assessed preoperatively at the 1st week (Pre1W), postoperative 1st month (Post1M) and 6th month (Post6M). Spatiotemporal parameters and MMP were assessed using the Win Track platform (Medicapteurs Technology, France) and functional states were assessed using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the Lequesne Index.

RESULTS

Significant improvements were found in the WOMAC and Lequesne Index values in the Post1M and Post6M periods compared to the preoperative period. However, the improvement in WOMAC and Lequesne Index scores in the Post6M period was significant compared to the scores in the Post1M period (p < 0.01). Spatiotemporal parameters deteriorated in the Post1M period, while improvements were observed in the Post6M period. We observed that patients had worse gait parameters in the near postoperative period than before surgery. It was the period with the greatest improvements in long-term outcomes.

SIGNIFICANCE

In the light of our study results, we think that early gait disturbances in patients who underwent direct TKA may be caused by physiological processes. Therefore, we believe that there is no need for any intervention for gait disorders that occur in the early postoperative period.

Fampridine-induced changes in walking kinetics are associated with clinical improvements in patients with multiple sclerosis

Gait dysfunction is common in patients with multiple sclerosis (PwMS). Treatment with prolonged-release fampridine (PR-fampridine) improves walking ability in some PwMS. Associated fampridine-induced changes in the walking pattern are still poorly understood but may provide a better understanding of the mechanisms underlying the beneficial drug effects. 61 PwMS were treated with PR-fampridine in a randomized, monocentric, double-blind and placebo-controlled clinical trial with crossover design (FAMPKIN). Drug-induced improvements in walking speed (Timed-25-Foot Walk; T25FW) and endurance (6-Minute Walk Test; 6MWT) were quantified. In this sub-study of the FAMPKIN trial, fampridine-induced changes in kinetic gait patterns were analyzed by pressure-based foot print analysis during treadmill walking. Vertical ground reaction forces were analyzed during different gait phases. Kinetic data of 44 PwMS was eligible for analysis. During double-blind treatment with PR-fampridine, patients performed significantly better in the T25FW and 6MWT than during placebo treatment (p < 0.0001 for both). At the group level (n = 44), there were no significant changes of gait kinetics under PR-fampridine vs. placebo. However, we found relevant changes of walking kinetics regarding forces during loading, single limb and pre-swing phase in a patient sub-group (n = 8). Interestingly, this sub-group demonstrated superior responsiveness to PR-fampridine in the clinical walking tests compared to those patients without any fampridine-induced changes in kinetics (n = 36). Our results demonstrate fampridine-induced changes in gait kinetics in a sub-group of PwMS. These gait pattern changes were accompanied by improved clinical walking performance under PR-fampridine. These results shed some light on the biomechanical changes in walking patterns underlying enhanced fampridine-induced gait performance.

Falls After Total Knee Arthroplasty: Frequency, Circumstances, and Associated Factors-A Prospective Cohort Study

BACKGROUND

Individuals with total knee arthroplasty (TKA) often experience pain and reduced balance control, which may predispose them to greater fall risk.

OBJECTIVE

The objective of this study was to determine the frequency and circumstance of falls and fall-related risk factors within a 6-month follow-up period in individuals after TKA.

DESIGN

This study was a prospective cohort study.

METHODS

Knee proprioception, the Balance Systems Evaluation Test, knee pain, knee extension and flexion muscle strength, knee range of motion, and balance confidence were evaluated in 134 individuals (39 men, 95 women; mean age = 66.3 years [SD = 6.6 years]) 4 weeks after TKA. Monthly follow-up sessions, via face-to-face or telephone interviews, were implemented to obtain data on fall incidence over 6 months.

RESULTS

Twenty-three individuals after TKA (17.2%) sustained at least 1 fall during the 6-month follow-up period. The median time of the first fall episode was 15 weeks after TKA. Of the 31 fall episodes, most occurred during walking (67.7%). Slipping (35.5%) and tripping (35.5%) were identified as the most frequent causes of falling. Most falls occurred at home (45.2%) or another indoor environment (29.0%). Multivariate binary logistic regression revealed that younger age (odds ratio: 0.91), reduced proprioception of the knee that had undergone surgery ("operated knee") (odds ratio: 1.62), reduced sensory orientation (odds ratio: 0.92), and greater operated knee pain (odds ratio: 1.68) were significantly associated with more falls during the follow-up period.

LIMITATIONS

The results of this study may be generalizable up to 6 months after TKA.

CONCLUSIONS

Intervention efforts should target deficits in knee proprioception and sensory orientation and operated knee pain to prevent future falls in individuals with TKA.

Normalized gait analysis parameters are closely related to patient-reported outcome measures after total knee arthroplasty

Up till now, only a weak connection could be shown between patient-related outcome measures (PROMs) and measurements obtained by gait analysis (e.g. speed, step length, cadence, ground reaction force, joint moments and ranges of motion) after total knee arthroplasty (TKA). This may result from the methodical problem that regression analyses are performed using data that are not normalized against a healthy population. It does appear reasonable to assume that patients presenting a physiological gait pattern are content with their joint. The more the gait parameters differ from a normal gait pattern the worse the clinical outcome measured by PROMs should be expected to be. In this retrospective study, 40 patients were enrolled who had received a gait analysis after TKA, and whose PROMs had been evaluated. A gender- and age-matched control group was formed out of a group of test persons who had already undergone gait analysis. Gait analysis was undertaken using the motion analysis system 3D Vicon with ten infrared cameras and three strength measuring force plates. The physiological gait analysis parameters were deduced from arithmetic mean values taken from all control patients. The deviances of the operated patients' gait analysis parameters from the arithmetic mean values were squared. From these values, the Pearson correlation coefficients for different PROMs were then calculated, and regression analyses were performed to elucidate the correlation between the different PROMs and gait parameters. In the regression analysis, the normalized cadence, relative gait speed of the non-operated side, and range of the relative knee moment of the operated side could be identified as factors which influence the Forgotten Joint Score (FJS-12). The explanation model showed an increase of the FJS-12 with minimisation of these normalized values corresponding to an approximation of the gait pattern seen in the healthy control group. The connection was strong, having a correlation coefficient of 0.708. A physiological gait pattern after TKA results in better PROMs, especially the FJS-12, than a non-physiological gait pattern does.

Pharmacological validation of voluntary gait and mechanical sensitivity assays associated with inflammatory and neuropathic pain in mice

The urgent need for more effective analgesic treatment options has prompted a re-evaluation of the behavioral tests used to assess pain in pre-clinical research, with an emphasis on inclusion of more voluntary, un-evoked behavioral assessments of pain. In order to validate voluntary gait analysis and a voluntary mechanical conflict-avoidance assay, we tested mouse models of neuropathy (spared nerve injury) and inflammation (complete Freund's adjuvant) alongside reflexive measures of mechanical and thermal hypersensitivity. To establish whether the observed changes in behavioral responses were pain-related, known analgesics (buprenorphine, gabapentin, carprofen) were also administered. Spared nerve injury persistently altered several gait indices, whereas complete Freund's adjuvant caused only transient changes. Furthermore, known analgesics could not reverse these gait changes, despite demonstrating their previously established efficacy in reflexive measures of mechanical and thermal hypersensitivity. In contrast, the mechanical conflict-avoidance assay demonstrated aversion in mice with neuropathy and inflammation-induced hypersensitivity, which could both be reversed by analgesics. We conclude that voluntary gait changes in rodent neuropathic and inflammatory pain models are not necessarily indicative of pain-related adaptations. On the other hand, mechanical conflict-avoidance represents a valid operant assay for quantifying pain-related behaviors in mice that can be reversed by known analgesics.

Association of frontal plane knee alignment with foot posture in patients with medial knee osteoarthritis

Background

To examine the association of radiographic frontal plane knee alignment with three-dimensional foot posture in patients with medial knee osteoarthritis (OA).

Methods

Participants in orthopedic clinics with Kellgren/Lawrence (K/L) grade ≥1 (88 patients and 88 knees; age, 61–91 years; 65.9% female) were enrolled. An anteroposterior radiographic view was used to assess the anatomical axis angle (AAA) after subtracting a sex-specific correction factor. The three-dimensional foot posture was also evaluated.

Results

Multiple regression analyses showed that increased corrected AAA (i.e., valgus direction) was independently associated with a decrease in the hallux valgus angle (regression coefficient: −0.40 per degree, 95% confidence interval [CI]: −0.72, −0.09; P = 0.013) and increase in the pronation angle of the calcaneus relative to floor (regression coefficient: 0.33 per degree, 95% CI: 0.10, 0.56; P = 0.005) adjusted for age, sex, and body mass index. The relationship between the corrected AAA and hallux valgus angle strengthened (regression coefficient: −0.60 per degree, 95% CI: −1.08, −0.13; P = 0.014) in varus-aligned knees examined separately (63 knees). The other foot postures (navicular height, navicular height/foot length, and rearfoot angle) were not significantly associated with corrected AAA.

Conclusions

Radiographic frontal plane knee alignment was associated with hallux valgus angle and calcaneus angle relative to the floor in patients with medial knee OA, particularly in varus-aligned knees. These results indicate a connection between altered frontal knee alignment and foot posture, which may be helpful in understanding the pathogenesis of altered foot posture observed in patients with knee OA.

Assessment of Gait Characteristics in Total Knee Arthroplasty Patients Using a Hierarchical Partial Least Squares Method

Quantitative gait analysis is an important tool in objective assessment and management of total knee arthroplasty (TKA) patients. Studies evaluating gait patterns in TKA patients have tended to focus on discrete data such as spatiotemporal information, joint range of motion and peak values of kinematics and kinetics, or consider selected principal components of gait waveforms for analysis. These strategies may not have the capacity to capture small variations in gait patterns associated with each joint across an entire gait cycle, and may ultimately limit the accuracy of gait classification. The aim of this study was to develop an automatic feature extraction method to analyse patterns from high-dimensional autocorrelated gait waveforms. A general linear feature extraction framework was proposed and a hierarchical partial least squares method derived for discriminant analysis of multiple gait waveforms. The effectiveness of this strategy was verified using a dataset of joint angle and ground reaction force waveforms from 43 patients after TKA surgery and 31 healthy control subjects. Compared with principal component analysis and partial least squares methods, the hierarchical partial least squares method achieved generally better classification performance on all possible combinations of waveforms, with the highest classification accuracy . The novel hierarchical partial least squares method proposed is capable of capturing virtually all significant differences between TKA patients and the controls, and provides new insights into data visualization. The proposed framework presents a foundation for more rigorous classification of gait, and may ultimately be used to evaluate the effects of interventions such as surgery and rehabilitation.

Knee Extensor Strength and Gait Characteristics After Minimally Invasive Unicondylar Knee Arthroplasty vs Minimally Invasive Total Knee Arthroplasty: A Nonrandomized Controlled Trial

BACKGROUND

In light of the existing lack of evidence, it was the aim of this study to compare gait characteristics and knee extensor strength after medial unicondylar knee arthroplasty (MUKA) with those after total knee arthroplasty (TKA), given the same standardized minimally invasive surgery (MIS) approach in both groups.

METHODS

Patients scheduled for MIS-MUKA or MIS-TKA as part of clinical routine were invited to participate. A posterior cruciate ligament-retaining total knee design was used for all MIS-TKA. A 3-dimensional gait analysis was performed preoperatively with a VICON system and at 8 weeks postoperative to determine temporospatial parameters, ground reaction forces, joint angles, and joint moments. At the same 2 times, isokinetic tests were performed to obtain peak values of knee extensor torque. A multivariate analysis of variance was conducted and included the main effects time (before and after surgery) and surgical group and the group-by-time interaction effect.

RESULTS

Fifteen MIS-MUKA patients and 17 MIS-TKA patients were eligible for the final analysis. The groups showed no differences regarding age, body mass index, sex, side treated, or stage of osteoarthritis. We determined neither intergroup differences nor time × group interactions for peak knee extensor torque or any gait parameters (temporospatial, ground reaction forces, joint angles, and joint moments).

CONCLUSION

It is concluded that MUKA is not superior to TKA with regard to knee extensor strength or 3-dimensional gait characteristics at 8 weeks after operation. As gait characteristics and knee extensor strength are only 2 of the various potential outcome parameters (knee scores, activity scores…) and quadriceps strength might take a longer time to recover, our findings should be interpreted with caution.

Foot pressure pattern and its correlation with knee range of motion limitations for individuals with medial knee osteoarthritis

OBJECTIVE

To determine the foot pressure pattern of individuals with medial knee osteoarthritis (OA) and to analyze its relation with knee flexion/extension range of motion.

DESIGN

Descriptive.

SETTING

Rehabilitation center.

PARTICIPANTS

Individuals with unilateral, painful medial knee OA (n=50; mean age, 75y; OA group) were enrolled as subjects, and young, healthy persons (n=50; mean age, 28y; young group) and elderly persons (n=44; mean age, 74y; elderly group) without any pain, deformity, or apparent OA changes in either knee were enrolled as controls.

INTERVENTION

Walking 10m at a comfortable speed.

MAIN OUTCOME MEASURES

Partial foot pressures as percentages of body weight (%PFP), anteroposterior length of the center of pressure (COP) path as a percentage of foot length (%Long), transverse width of the COP path as a percentage of foot width (%Trans), knee flexion/extension range of motion (in the OA group).

RESULTS

The %PFP values for the heel and hallux, %Long, and %Trans were all significantly lower in the OA group than in controls (P<.001, all). Within the OA group, a limited range of knee extension was significantly associated with a short %Long (P<.001) but not with %Trans.

CONCLUSIONS

Individuals with medial knee OA exhibited low pressure on the heel and hallux and short %Long of the COP path, and limitation of knee extension was associated with shortness of %Long. The shortness of %Long in the OA group likely resulted from insufficient knee extension during the heel-contact phase associated with low pressure on the heel. %Long is a useful parameter in gait analysis by using a foot pressure measurement system.

Prospective study of gait function before and 2 years after total knee arthroplasty

PURPOSE

To perform a prospective evaluation of gait before and 2 years after total knee arthroplasty (TKA) and examine the influence of comorbidity and other joint problems on gait characteristics and their improvement after TKA.

METHODS

One hundred and eleven patients scheduled for TKA took part (34 men, 65 ± 10 y; 77 women, age 68 ± 9 y). Gait velocity, cadence, and ground reaction force parameters were measured before and 2 years after surgery. Patients completed a questionnaire to rate their pain and other joint problems. Comorbidity was measured with the American Society of Anaesthesiologists (ASA) score.

RESULTS

Two years after TKA there were significant improvements (each p<0.05) in gait velocity and cadence and most of the ground reaction parameters, though forces during loading/unloading remained lower for the operated leg than for the contralateral leg. Higher comorbidity and other painful joints of the lower extremities/spine had a consistent, negative influence (p<0.05) on the absolute values achieved for the gait parameters although their improvement compared with baseline was independent of these factors.

CONCLUSIONS

Comorbidity and other joint problems negatively influenced gait performance. These confounders should be taken into account when setting realistic patient expectations and when interpreting the success of TKA in the individual patient. Improvement in gait is however still possible, within the bounds of concomitant comorbidity.

Foot pressure distribution in patients with gonarthrosis

BACKGROUND

When standing, leg alignment is controlled by supinating or pronating the subtalar joint, corresponding to valgus or varus deformity of the knee joint. However, in the gait cycle, it is not clear whether the abnormal alignment can be compensated.

OBJECTIVE

The purpose of this study was to evaluate the control of leg alignment in the latter half of the gait cycle.

METHODS

Forty-six patients (46ft) with unilateral gonarthrosis (16 men, 30 women; mean age, 69 years) were evaluated for foot pressure distributions of the forefoot and midfoot. The apparatus used was a walkway in which a tactile force- and pressure-measurement system was installed. Patients were classified by femorotibial angle, pronation-supination index (PSI), foot pressure distribution of the point of the metatarsal head, and passage point of the center of pressure (COP) at the toe.

RESULTS

A larger femorotibial angle was associated with a larger PSI, and contact such that the load is applied more strongly to the pressure points of the metatarsal heads laterally. In addition, with a larger femorotibial angle, COP at the toe tended to pass through the second toe. In other words, foot sole contact is significantly more lateral with varus knee, whereas foot sole contact tends to be more medial with valgus knee.

CONCLUSIONS

Analysis revealed that severe abnormal leg alignment was not sufficiently compensated for by the forefoot and midfoot in the latter half of the gait cycle. When treating the forefoot and midfoot, precautions are necessary in patients with knee deformities.

Does ipsilateral knee pain improve after hip arthroplasty?

BACKGROUND

Intraarticular hip disease is commonly acknowledged as a cause of ipsilateral knee pain. However, this is based primarily on observational rather than high-quality evidence-based studies, and it is unclear whether ipsilateral knee pain improves when hip disease has been treated.

QUESTIONS/PURPOSES

We asked whether (1) hip disease was associated with preoperative ipsilateral knee pain and (2) ipsilateral knee pain would improve after hip arthroplasty.

PATIENTS AND METHODS

We retrospectively assessed knee pain in 255 patients who underwent hip arthroplasties between 2006 and 2008. The WOMAC pain score of each joint was the primary outcome measure, which was obtained prospectively before surgery and at 3 months and 1 year postoperatively. Of the 255 patients, 245 (96%) had followup data obtained at 3 months or 1 year.

RESULTS

Preoperatively, ipsilateral knee pain was observed more frequently than contralateral knee pain (55% versus 18%). Preoperative ipsilateral knee pain scores were worse than contralateral knee pain scores (mean, 80 versus 95). Ipsilateral knee pain improved at 3 months and 1 year. When compared with the scores for contralateral knee pain at 3 months (95) and 1 year (96), there were no differences between knees.

CONCLUSIONS

Our observations suggest hip disease is associated with ipsilateral knee pain and that it improves after hip arthroplasty. This should be considered during preoperative evaluation for patients with hip and knee pain.

LEVEL OF EVIDENCE

Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements

BACKGROUND

One long-held tenet of total knee arthroplasty is that implant durability is maximized when postoperative limb alignment is corrected to 0° ± 3° relative to the mechanical axis. Recently, substantial health-care resources have been devoted to computer navigation systems that allow surgeons to more often achieve that alignment. We hypothesized that a postoperative mechanical axis of 0° ± 3° would result in better long-term survival of total knee arthroplasty implants as compared with that in a group of outliers.

METHODS

Clinical and radiographic data were reviewed retrospectively to determine the fifteen-year Kaplan-Meier survival rate following 398 primary total knee arthroplasties performed with cement in 280 patients from 1985 to 1990. Preoperatively, most knees were in varus mechanical alignment (mean and standard deviation, 6° ± 8.8° of varus [range, 30° of varus to 22° of valgus]), whereas postoperatively most knees were corrected to neutral (mean and standard deviation, 0° ± 2.8° [range, 8° of varus to 9° of valgus]). Postoperatively, we defined a mechanically aligned group of 292 knees (with a mechanical axis of 0° ± 3°) and an outlier group of 106 knees (with a mechanical axis of beyond 0° ± 3°).

RESULTS

At the time of the latest follow-up, forty-five (15.4%) of the 292 implants in the mechanically aligned group had been revised for any reason, compared with fourteen (13%) of the 106 implants in the outlier group (p = 0.88); twenty-seven (9.2%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, wear, or patellar problems, compared with eight (7.5%) of the 106 implants in the outlier group (p = 0.88); and seventeen (5.8%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, or wear, compared with four (3.8%) of the 106 implants in the outlier group (p = 0.49).

CONCLUSIONS

A postoperative mechanical axis of 0° ± 3° did not improve the fifteen-year implant survival rate following these 398 modern total knee arthroplasties. We believe that describing alignment as a dichotomous variable (aligned versus malaligned) on the basis of a mechanical axis goal of 0° ± 3° is of little practical value for predicting the durability of modern total knee arthroplasty implants.

Is gait normal after total knee arthroplasty? Systematic review of the literature

BACKGROUND

Development or retention of abnormal gait patterns after total knee arthroplasty may be related to the predictable pattern of further deterioration of other lower extremity joints. The purpose of this study was to determine whether gait mechanics are abnormal after total knee arthroplasty by conducting a systematic review of the literature.

METHODS

Articles were identified by searching the following electronic databases: PubMed, Cinahl, Web of Science: 221 references were retrieved. The titles and abstracts were reviewed to identify studies that potentially met the inclusion criteria. These articles were retrieved for further assessment. Ten articles met the inclusion criteria and were included in the review.

RESULTS

There was a lack of common variables across the studies. Studies indicated smaller peak knee flexion during weight acceptance and less knee flexion excursion in total knee arthroplasty subjects compared to controls. Knee angle at foot strike was generally similar in arthroplasty groups compared to controls. Maximum external knee flexion moment was generally lower in arthroplasty groups compared to controls. Conflicting results were found for other knee moments. Several other stance phase variables were reported by individual studies only.

CONCLUSIONS

Peak knee flexion and knee flexion excursion during weight acceptance are smaller in the operated knee following total knee arthroplasty compared to healthy controls. There may also be a smaller peak knee flexion moment after arthroplasty compared to controls. Knee mechanics in the operated knee are not normal after total knee arthroplasty. Abnormal gait mechanics may predispose the individual to further joint degeneration, particularly in the nonoperated knee. Further research should focus on the effects of unilateral total knee arthroplasty on the nonoperated knee.

The application of support vector machines for detecting recovery from knee replacement surgery using spatio-temporal gait parameters

Knee osteoarthritis (OA) is one of the leading causes of disability among the elderly which, depending on severity, may require surgical intervention. Knee replacement surgery provides pain relief and improves physical function including gait. However gait dysfunction such as altered spatio-temporal measures may persist after the surgery. In this paper, we investigated the application of support vector machines (SVM) to classify gait patterns indicative of knee OA before surgery based on 12 spatio-temporal gait parameters and investigated whether SVMs could be used to predict gait improvement 2 and 12 months following knee replacement surgery. Test results for the pre-operative data indicated that the SVM could successfully identify individuals with OA gait from the healthy using all of the spatio-temporal parameters with a maximum leave one out accuracy of 100% for the training set and 88.89% for the test set. Findings indicated that three patients still had altered gait patterns 2 months post-knee replacement surgery, but all individuals showed improvement in gait 12 months following surgery. Consequently, the SVM detected improvement in gait function due to surgical intervention at 2 and 12 months following knee replacement which coincided with clinical assessment of the knee. This suggests that spatio-temporal parameters contain important discriminative information which may be used for the identification of pathological gait using an SVM classifier.

Correlation between objective gait parameters and subjective score measurements before and after total knee arthroplasty

The absence of uniformity, the use of different terminologies, and the diversity of methods used to translate numerical data into clinical outcomes have been described as potential problems when dealing with clinical knee scores for total knee arthroplasty (TKA). Gait analysis is believed to provide more objective parameters. The aim of the present study was to obtain information about the correlation between the outcome in terms of locomotion and the clinical knee score after TKA. Thirty consecutive patients awaiting TKA were involved in the study. One day prior to surgery and 3 months postoperatively, data pertaining to the Hospital for Special Surgery Score (HSS) and the Knee Society Score (KSS) (subgroups 'pain', 'knee', 'function' and 'total sum') were analyzed for correlations with kinematic and temporospatial parameters of gait analysis. At a significance-level of p</=0.001 moderate correlations (0.4<r<0.6) were found preoperatively, particularly between 'max knee flexion swing' and the function-subscores of HSS and KSS and the 'KSS total'. High correlations (0.6<r<0.8) were ascertained for 'stride length' and 'gait velocity' with 'KSS function'. High correlations were also determined between 'stride length' and 'KSS total' and between 'gait velocity' and 'HSS function'. The only correlation found postoperatively was between 'max pelvic obliquity stance' and 'KSS knee' (r=0.770, p<0.001). We conclude that the 'function' subscores of KSS and HSS are highly suitable to assess the functional capacity of patients scheduled for TKA. However, because no adequate correlations between knee scores and gait parameter were found postoperatively, we cannot recommend the abandonment of gait analysis when monitoring the functional benefit of TKA.

Support Vector Machines for detecting recovery from knee replacement surgery using quantitative gait measures

Knee osteoarthritis (OA) is one of the leading causes of disability among the elderly which, depending on severity, may require surgical intervention. Knee replacement surgery provides pain relief and improves physical function including gait. Gait dysfunction such as altered spatio-temporal measures and gait asymmetry both pre- and post-surgery, however, may still persist after the surgery. In this paper, we investigated the application of Support Vector Machines (SVM) to classify gait patterns pertaining to knee OA before surgery based on spatio-temporal gait parameters and to investigate whether SVM can assess gait improvement at 2 months following knee replacement surgery. Test results indicate that the SVM can identify the OA gait from the healthy ones with a max leave one out (LOO) accuracy of 94.2%. When feature selection technique was applied, the accuracy improved to 97.1% using only 2 symmetry index features. Further, the post surgery test results by the SVM indicated 4 patients still had altered gait. This suggests that subject gait symmetry should be monitored closely after surgery to assess treatment outcomes and recovery.

Peripheral arterial disease affects ground reaction forces during walking

OBJECTIVE

Claudication is the most common manifestation of peripheral arterial disease (PAD), producing significant ambulatory compromise. The gait of claudicating patients has been evaluated using primarily temporal and spatial parameters. With the present study, we used advanced biomechanical measures to further delineate the ambulatory impairment of claudicating patients. We hypothesized that the claudicating legs of PAD patients have an altered kinetic gait pattern compared with normal legs from control subjects.

METHODS

Ambulation kinetics (ground reaction forces) were evaluated in claudicating patients and compared with age-matched healthy controls. Forces were analyzed in the vertical, anterior-posterior, and medial-lateral directions. Time from heel touch-down to toe-off (stance time) and time spent in double-limb support were also evaluated.

RESULTS

The study recruited 14 PAD patients (age, 58 +/- 3.4 years; weight, 80.99 +/- 15.64 kg) with femoropopliteal occlusive disease (ankle-brachial index [ABI], 0.56 +/- 0.03) and five controls (age, 53 +/- 3.4 years; weight, 87.38 +/- 12.75 kg; ABI, >or=1.00). Vertical force curve evaluation demonstrated significant flattening in claudicating patients resulting in a lower and less fluctuant center of mass when ambulating. In the anterior-posterior direction, claudicating patients demonstrated significantly decreased propulsion forces. In the medial-lateral direction, they had significantly increased forces consistent with wider steps and an inability to swing their legs straight through. Claudicating patients demonstrated a greater stance time and time in double limb support compared with healthy controls. Most importantly, gait abnormalities were present before the onset of claudication, with gait worsening after the onset of claudication.

CONCLUSION

Claudicating patients demonstrate significant gait impairments that are present even before they experience any limb discomfort. These alterations may make them feel more stable and secure while attempting to minimize use of the affected limb. Advanced biomechanical analysis, using ambulation kinetics, permits objective and quantitative evaluation of the gaits of claudicating patients. Such evaluation may point to new rehabilitation strategies and provide objective measurement of functional outcomes after medical and surgical therapy.

Gait analysis of patients following total knee replacement: a systematic review

Gait analysis has been used to objectively measure patients' function following total knee replacement (TKR). Whilst the findings of this research may have important implications for the understanding of the outcomes of TKR, the methodology of existing research appears to be diverse and many of the results inconsistent. The objective of this systematic review was to synthesise reported findings and to summarise the methods used by researchers in this field. Eleven articles published in the medical literature that used gait analysis to compare patients following TKR with controls were identified for inclusion in this review. Each article was assessed for methodologic quality and data was compared across studies through the calculation of effect sizes. Consistently large effect sizes showed that patients following TKR walk with less total knee motion during gait and with less knee flexion during swing than controls. Kinetic discrepancies between patients and controls were also identified. The substantial methodologic differences between studies may contribute to the inconsistencies in reported findings for many gait outcomes. Future research is needed to determine the clinical relevance of these findings.

Pain relief in knee osteoarthritis reduces the propensity to trip on an obstacle

The pain associated with knee osteoarthritis (OA) has been shown to lead to an increased propensity to trip on an obstacle. Pain-relieving intra-articular injections are widely utilized in the treatment of knee OA. This study examined the effects of pain-relieving intra-articular knee injections on the ability to avoid contacting a suddenly appearing obstacle in patients with knee OA. Obstacle avoidance success rates, pain, body mass index, visual acuity, contrast sensitivity, depth perception, and single-leg stance duration were evaluated in nine patients with painful osteoarthritis of the knee and 14 age-matched healthy control subjects. Obstacle avoidance success rates, pain, and single leg stance duration were tested a second time in the patients with knee OA after they received their injections, which contained a fast-acting local anesthetic to provide rapid pain relief. After receiving the pain-relieving knee injections, patients with knee OA had 48% less pain and were 31% more successful in avoiding stepping on the obstacle. However, after receiving the injection, the obstacle avoidance success rates remained 20% less than those of the healthy controls. The results of this study suggest that knee pain-relief can decrease the propensity of people with painful knee OA to trip and fall over an obstacle. However, pain-relief alone did not return the patients with knee OA in this study to a disease-free risk of tripping.

The vertical projection of the sum of the ground reactive forces of a standing patient is not the same as the C7 plumb line: a radiographic study of the sagittal alignment of 153 asymptomatic volunteers

STUDY DESIGN

A radiographic study of 153 normal volunteers.

OBJECTIVES

1) To test the hypothesis that the vertical projection of the sum of the ground reactive forces of a standing patient is located in the same place in the sagittal plane as the C7 plumb line; 2) to determine if there are consistent geometric relationships between the location of the top of the spine and the pelvis in the sagittal plane that occur in individuals without symptoms of back pain or radiographic evidence of deformity.

SUMMARY OF BACKGROUND DATA

Defining the optimal state of spinal balance is difficult. A full understanding of the compensatory relationships between the spine, pelvis, and lower limbs remains elusive.

METHODS

A total of 153 normal volunteers were subjected to radiographic examination using a digital force plate, a stabilized standing position, a standardized radiographic technique, and the computerized measurement of sagittal alignment.

RESULTS

1) The C7 plumb line and the gravity line in a stabilized standing position are not located in the same place; 2) the association between the center of T1 and the sacral endplate may be an anatomic constant and a marker of spinal balance in individuals without symptoms of back pain or radiographic evidence of deformity, and is determined by the formula 99 degrees - 0.1 degrees (sacral slope).

CONCLUSIONS

We speculate that this information will be very helpful in evaluating symptomatic spinal disease in the context of the overall alignment of the spine and pelvis.

Preliminary results after total knee arthroplasty without femoral trochlea: evaluation of clinical results, quality of life and gait function

Evaluation of the clinical and functional results of a new prosthetic knee design with conservation of the physiologic properties of the patellofemoral joint. After total knee arthroplasty there are often patella problems. Some of them may be a result of excessive retropatellar pressure caused by the prosthetic design. Twelve patients with an average age of 68.6 years were evaluated after a follow-up of 16.4 months after implantation of a new prosthetic design. The clinical results were evaluated with the Hospital for Special Surgery Scores (HSS) and the Knee Society Clinical Rating Systems (KSS). Pain was rated on a Visual Analog Scale (VAS). Quality of life was determined with the SF-36 questionnaire. Furthermore, clinical gait analysis was performed with a 3D motion analysis system and force plates as well as surface electromyography of seven lower extremity muscles. The HSS-Score reached a mean value of 79.3 points. The KSS reached 82.3 points for the knee score and 75 points for the functional score. The VAS for pain revealed an average value of 1.7. For the gait analysis only three parameters indicated significant differences between the affected and the contralateral leg. The mean EMG amplitude revealed a significant difference only for the biceps femoris. The clinical and functional outcome of a new prosthesis design show satisfactory results. Even if the presented results appear promising, a further application and long term results are needed.

Does bilateral total knee arthroplasty affect gait in women?: comparison of gait analyses before and after total knee arthroplasty compared with normal knees

We performed gait analysis of 24 patients with bilateral knee osteoarthritis (OA) before, 1 year, and 2 years after bilateral total knee arthroplasty and compared these results to 12 normal controls. Cadence was significantly decreased in OA patients when compared with controls. Step and stride lengths were significantly different preoperatively (shorter) and postoperatively (P < .05), but postoperative results showed no significant difference when compared with normal controls (P < .05). Step and stride times were significantly different (P < .05) between the preoperative OA group and controls, but no difference was seen with the postoperative measurements when compared with controls. In the OA group, the mean vertical component of the ground reaction forces expressed as percent body weight was significantly lower when compared with controls and postoperative results. No correlation was found between the preoperative and postoperative clinical scores and objective data obtained from gait analysis. Our results demonstrate that gait analysis is not a useful tool in evaluating the success of total knee arthroplasty patient.

Plantar pressure distribution during gait in athletes with functional instability of the ankle joint: preliminary report

This study addressed the hypothesis that gait characteristics differ between normal subjects and athletes suffering from functional instability (FI) of the ankle joint. FI of the ankle joint is one of the most common residual disabilities after an acute ankle sprain. However, the influences of the FI of the ankle joint on the gait characteristics are not well understood. Athletes suffering from FI of the ankle joint and healthy control subjects were examined. Pressure, area, and force during gait were measured using a pressure measuring system. These in vivo plantar pressure measurements were performed during free walking. The foot angle and the pronation-supination index were calculated. Those in the FI group were found to exhibit a significantly lower dynamic foot angle and a greater pronation-supination index at the midsupport phase of gait than those in the control group. The results showed increased adduction-supination of the foot at the stance phase of gait in those with FI of the ankle joint.

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 degrees 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 degrees varus-valgus alignment and/or extension defect of 10 degrees 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.

Clinical and functional comparison of uni- and bicondylar sledge prostheses

The aim of the present study was the evaluation of differences in clinical results, proprioceptive performance and gait in patients with unicondylar and bicondylar sledge prostheses of the knee. In a retrospective study, 17 patients with unicondylar sledge prostheses were compared with 15 patients with bicondylar sledge prostheses. Clinical examination was rated using HSS, Knee Society, and patellar scores and a visual analogue scale for pain. Proprioceptive performance was examined using sway measurements during single leg stance on a force platform. In addition, the patients underwent 3-D gait analysis including measurements of ground reaction forces and surface electromyographic (EMG) investigation of the lower extremity. Comparing both patient groups in clinical scores, gait, EMG and proprioception, no significant differences were found. Implantation of bicondylar sledge prostheses retaining both cruciate ligaments achieves functional results as good as unicompartmental arthroplasty. The presented results might encourage future research on new models of total joint replacement with preservation of both cruciate ligaments.

Bilateral total knee arthroplasty increases the propensity to trip on an obstacle

Tripping over an obstacle is the most frequent cause of falls. We examined the effects of total knee arthroplasty on obstacle avoidance success rates in older adults. Obstacle avoidance success rates, body mass index, visual acuity, contrast sensitivity, depth perception, and single-leg stance duration were evaluated in 29 subjects who had bilateral total knee arthroplasties (age range, 72.6 +/- 5.4 years) and 27 age-matched healthy control subjects (age range, 70.6 +/- 5.5 years). The patients who had total knee arthroplasties had a lower obstacle avoidance success rate, lower single-leg stance duration, and greater body mass index than control subjects. Age, contrast sensitivity, and depth perception were not different between patients who had total knee arthroplasties and control subjects. Obstacle avoidance success rates decreased linearly as single-leg stance duration decreased in the control group and across all groups, but not in the group that had total knee arthroplasties. Linear relationships between obstacle avoidance success rates and body mass index existed for all subjects but not for the group that had total knee arthroplasties or the control group individually. Total knee arthroplasty reduces obstacle avoidance success rate, suggesting that persons who have total knee arthroplasties have an increased propensity to trip on an obstacle and fall. Increased body mass index and decreased single-leg stance duration in patients who have total knee arthroplasties are associated with a decreased obstacle avoidance success rate.

Osteoarthritis of the knees increases the propensity to trip on an obstacle

Tripping on an object is the most frequent cause of falls. We examined the effects of painful osteoarthritis of the knee on obstacle avoidance success rates in older adults. Obstacle avoidance success rates, pain, body mass index, visual acuity, contrast sensitivity, depth perception, and single-leg stance duration were evaluated in 17 patients with painful osteoarthritis of the knees (age range, 59.6 +/- 8.1 years) and 14 age-matched healthy control subjects (age range, 61.1 +/- 10.0 years). The patients with osteoarthritis of the knees had a 37% lower obstacle avoidance success rate, a 54% lower single-leg stance duration, and a 24% greater body mass index than the control subjects. Age, visual acuity, contrast sensitivity, and depth perception were not different between the two groups. Obstacle avoidance success rates and single-leg stance durations decreased linearly as pain increased in the patients with osteoarthritis of the knees. Obstacle avoidance success rates also decreased linearly as single-leg stance duration decreased in the patients with osteoarthritis of the knees. Osteoarthritis of the knees reduced obstacle avoidance success rates, supporting epidemiologic studies that have found osteoarthritis to be a risk factor for falls. This study showed that pain associated with osteoarthritis of the knees increased the propensity to trip on an obstacle (the greater the pain the greater the propensity to trip and fall) and underscores the importance of treating pain associated with osteoarthritis.

Quantitative gait analysis after medial unicompartmental knee arthroplasty for osteoarthritis

This study characterized the footstep pattern and knee kinematics during walking in 12 patients who had undergone unicompartmental knee arthroplasty for unilateral medial compartment osteoarthritis. Patients had all achieved a successful recovery and were tested at least 1 year after surgery. Gait analysis was conducted during self-selected comfortable and fast walking conditions using a 3-dimensional motion analysis system and electronic walkway. Results showed that patients were able to increase their walking speed by 28% by increasing both stride length and cadence. All but one patient showed a biphasic pattern of flexion-extension motion about the treated knee. In 8 of 12 patients, significant increases in knee flexion were seen in the treated limb compared with the contralateral limb, the cause and ramifications of which are yet to be determined.

Systematische Analyse der Änderung der Bodenreaktionskräfte bei Hüft- und Kniearthrose prä- und postoperativ. Systematic Analysis of Ground Reaction Forces Before and After Hip- and Knee Arthroplasty

In this prospective study we employed a newly developed gait analysis system to compare the ground reaction force patterns in 15 patients before and after total hip or knee replacement. In this system, data are measured separately for each limb. Measured data were also obtained from 30 healthy adults and compared with those obtained from the patient group. We analysed the three-dimensional force patterns, impulse, frequency, stride and double stance, and compared changes in the postoperative gait patterns. The vertical force maxima Fy identify the peak forces obtaining during walking. The results showed significantly increased (p < 0.05) postoperative force maxima Fy2 and Fy3 for both knee replacement (Fy2: 82.48 to 86.17 and Fy3: 96.09 to 99.35% body weight, pre- and postoperatively, respectively) and hip replacement (Fy2: 84.44 to 88.08 and Fy3: 98.63 to 101.96% body weight, pre- and postoperatively, respectively). The ADAL system proved suitable for the easy performance of gait analysis, and thus may be of future value in the area of clinical quality assurance.

A practical guide to gait analysis

The act of walking involves the complex interaction of muscle forces on bones, rotations through multiple joints, and physical forces that act on the body. Walking also requires motor control and motor coordination. Many orthopaedic surgical procedures are designed to improve ambulation by optimizing joint forces, thereby alleviating or preventing pain and improving energy conservation. Gait analysis, accomplished by either simple observation or three-dimensional analysis with measurement of joint angles (kinematics), joint forces (kinetics), muscular activity, foot pressure, and energetics (measurement of energy utilized during an activity), allows the physician to design procedures tailored to the individual needs of patients. Motion analysis, in particular gait analysis, provides objective preoperative and postoperative data for outcome assessment. Including gait analysis data in treatment plans has resulted in changes in surgical recommendations and in postoperative treatment. Use of these data also has contributed to the development of orthotics and new surgical techniques.