Gait analysis and hip extensor function early post total hip replacement

[Analysis of kinematic changes of hip joint after total hip arthroplasty]

Objective

To analyze the kinematic changes of the hip joint after total hip arthroplasty (THA) through three-dimensional gait analysis.

Methods

Patients with hip joint diseases admitted between October 2022 and June 2023 were selected as the subjects. The patients who met the selective criteria were finally included in the THA group. The healthy volunteers matched with the THA group in the same age were included as the control group. Baseline data including age, gender, body mass index (BMI), and laterality were compared between the two groups. The Harris hip score (HHS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score were recorded preoperatively and at last follow-up in the THA group. Three-dimensional motion capture system was utilized to collect spatiotemporal parameters and kinematic data during walking, including stride length, cadence, and maximum/minimum values, range of motion (ROM) in hip joint abduction/adduction, external/internal rotation, and flexion/extension, as well as gait scores. Differences between the two groups were analyzed. Additionally, the correlation between gait scores and postoperative HHS and WOMAC scores were analyzed in the THA group. Finally, the kinematic data of each degree of freedom (DOF) were fitted into a gait diagram, and the dynamic changes of the 3-DOF of the hip joint during the gait cycle were quantitatively analyzed.

Results

There was no significant difference in gender, age, laterality, and BMI between the two groups ( n=20, P>0.05). The mean follow-up time in the THA group was 9.9 months (range, 6-12 months). The HHS and WOMAC scores at last follow-up in the THA group showed significant improvement when compared with preoperative scores ( P<0.05). Gait scores were positively correlated with postoperative HHS score ( r=0.585, P=0.007) and negatively correlated with WOMAC score ( r=-0.619, P=0.004). There was no significant difference in stride length and cadence between the THA and control groups ( P>0.05), but gait score was significantly lower in the THA group than in the control group ( P<0.05). There was no significant difference in maximum and minimum values of flexion/extension, external/internal rotation, and abduction/adduction between the two groups ( P>0.05); however, ROM in the THA group was significantly lower than that in the control group ( P<0.05). There were significant differences between the two groups of flexion/extension in multiple phases of the gait cycle ( P<0.05).

Conclusion

Early post-THA hip joint kinematics exhibit relative adduction, external rotation, and flexion during the gait cycle compared to normal individuals, with incomplete recovery of kinematic parameters in three degrees of freedom. Significant differences in flexion are observed at multiple phases of the gait cycle compared to normal individuals.

Stepping Beyond Counts in Recovery of Total Hip Arthroplasty: A Prospective Study on Passively Collected Gait Metrics

Gait quality parameters have been used to measure recovery from total hip arthroplasty (THA) but are time-intensive and previously could only be performed in a lab. Smartphone sensor data and algorithmic advances presently allow for the passive collection of qualitative gait metrics. The purpose of this prospective study was to observe the recovery of physical function following THA by assessing passively collected pre- and post-operative gait quality metrics. This was a multicenter, prospective cohort study. From six weeks pre-operative through to a minimum 24 weeks post-operative, 612 patients used a digital care management application that collected gait metrics. Average weekly walking speed, step length, timing asymmetry, and double limb support percentage pre- and post-operative values were compared with a paired-sample t-test. Recovery was defined as the post-operative week when the respective gait metric was no longer statistically inferior to the pre-operative value. To control for multiple comparison error, significance was set at p < 0.002. Walking speeds and step length were lowest, and timing asymmetry and double support percentage were greatest at week two post-post-operative (p < 0.001). Walking speed (1.00 ± 0.14 m/s, p = 0.04), step length (0.58 ± 0.06 m/s, p = 0.02), asymmetry (14.5 ± 19.4%, p = 0.046), and double support percentage (31.6 ± 1.5%, p = 0.0089) recovered at 9, 8, 7, and 10 weeks post-operative, respectively. Walking speed, step length, asymmetry, and double support all recovered beyond pre-operative values at 13, 17, 10, and 18 weeks, respectively (p < 0.002). Functional recovery following THA can be measured via passively collected gait quality metrics using a digital care management platform. The data suggest that metrics of gait quality are most negatively affected two weeks post-operative; recovery to pre-operative levels occurs at approximately 10 weeks following primary THA, and follows a slower trajectory compared to previously reported step count recovery trajectories.

Randomized controlled trial to compare conventional physiotherapy with task-oriented exercises after total hip replacement

BACKGROUND

Different interventions are used during rehabilitation after hip replacement surgery, but it is unclear if task-oriented exercise is more effective than conventional physiotherapy.

OBJECTIVE

This study compared the effectiveness of conventional physiotherapy (CPT) programme with task-oriented exercise (TOE) on hip pain, function, static and dynamic balance during the early rehabilitation stage after total hip replacement.

METHODS

This randomized controlled parallel-group trial was executed in an inpatient physical medicine and rehabilitation centre. The study included 40 patients who were randomly classified into CPT and TOE groups (n= 20 in each). Hip pain (assessed by visual analogue scale), function in the operated leg (assessed by modified Harris Hip Score, mHHS), static balance (assessed by Abili Balance analyser system) and dynamic balance (assessed by Berg Balance Scale) were evaluated at baseline and after 18 days of rehabilitation. Cohen's effect size (d) was calculated.

RESULTS

Greater pain reduction (p< 0.05; d= 0.08) was observed after TOE (1.6 ± 0.68 scores) compared with the CPT programme (2.2 ± 0.83 scores). Hip function assessed by the modified mHHS improved more (p< 0.05; d= 0.30) in the TOE group (73.45 ± 6.23 scores) than in the CPT group (54.90 ± 6.28 scores). Static balance improved significantly in both groups after the interventions but did not differ significantly between the groups. The improvement in dynamic balance was significantly greater (p< 0.05; d= 0.45) after TOE (50.55 ± 1.57 scores) than after CPT (38.55 ± 3.43 scores).

CONCLUSION

Both interventions reduced pain and improved function of the operated leg and static and dynamic balance. The effect on hip function was superior for TOE compared with CPT.

A prospective randomised comparison of earlier function after total hip arthroplasty with a mini posterior approach or supercapsular percutaneously-assisted total hip approach: a gait analysis study

BACKGROUND

The supercapsular percutaneously-assisted total hip (SuperPATH) approach is a muscle sparing surgical technique for total hip arthroplasty (THA). The literature reports good clinical and functional results of the SuperPATH technique in the short term. We aimed to compare early outcomes and gait analysis of THA using the mini posterior approach (MPA) and supercapsular percutaneously-assisted total hip (SuperPATH) approach.

METHODS

44 patients who underwent THA, were randomly allocated to either MPA or SuperPATH. The data were then collected prospectively (preoperatively and postoperatively at 6 weeks). Plain anteroposterior radiographs of the pelvis and instrumental gait analysis were obtained. The visual analogue scale (VAS), Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Scores (HOOS) were used to assess functional and clinical outcomes.

RESULTS

No significant difference was found in patients' surgical outcomes. Patients in the SuperPATH group had less pain according to the VAS score at follow-up than the MPA group (p < 0.01). There was also a significant improvement in HHS and HOOS scores for all patients (p < 0.001) with the SuperPATH group showing superior changes. The comparison of mean differences in gait velocity between preoperative and 6 weeks postoperative result, revealed improvement in the SuperPATH group over the MPA group (p = 0.06). Limping was more persistent in the MPA group. Kinematic parameters demonstrated improved hip joint excursion slightly higher in the MPA group. There was no significant improvement in kinetic and kinematic parameters at different walking moments for all patients at 6 weeks compared to preoperative gait patterns.

CONCLUSIONS

SuperPATH and MPA both show excellent results. This study reveals that the SuperPATH technique was associated with lower postoperative pain levels, and higher physical function and quality of life. Improved functional outcomes allowed earlier postoperative rehabilitation and faster recovery. Specific improvement in gait patterns were identified with nonsignificant differences between the 2 approaches at 6 weeks follow-up.

Analysis of biomechanical gait parameters in patients after total hip replacement operated via anterolateral approach depending on size of the femoral head implant: retrospective matched-cohort study

INTRODUCTION

Total hip replacement (THR) is considered one of the most effective medical procedures in treatment of osteoarthritis. Since its introduction, there has been a worldwide debate over proper implant selection in terms of size, bearing type and shape. Following study was designed to assess the importance of femoral head size in long-term follow-up.

MATERIALS AND METHODS

A cohort of 30 patients with primary end stage osteoarthritis who underwent total hip replacement was analysed retrospectively. A homogenous group was chosen with no major differences in BMI. Patients' gait parameters were measured in a biomechanics laboratory using the 3D BTS Smart system. WOMAC and VAS questionnaires were used to assess patient reported outcome.

RESULTS

The subgroup with larger implant head size had several outcomes significantly superior to the subgroup with standard head size and non-inferior to healthy hips. Following variables were measured during this study: time of support phase, time of swing phase, double support time, walking hip extension angle.

CONCLUSIONS

Use of larger sized femoral heads during THR gives better results in terms of gait pattern. Since restoring the gait pattern is one of the aspects of rehabilitation and returning to daily activities it seems to be an important observation.

Is simultaneous bilateral total hip arthroplasty deleterious in a biomechanical point of view? A comparative gait analysis study

Purpose

Uni- or bilateral hip osteoarthritis is a common disease generating pain, stiffness, and functional disabilities. Changes in the normal walking with higher energy expenditures are observed. Facing a cruel lack of biomechanical data, we decided to analyse the impact on the walking of single and simultaneous bilateral total hip arthroplasties (THA).

Method

We conducted a prospective monocentric study, comparing two matched groups of 15 patients able to walk with symptomatic isolated uni- (group 1) or bilateral HO (group 2) and treated respectively by unilateral THA (UTHA) or simultaneous bilateral THA (SBTHA). Surgery was performed by a single surgeon with a direct anterior approach and approved by local ethical committee. Walking was assessed by a « 3D Gait analysis motion» pre and at 6 months post operatively.

Result

In the UTHA group, recovery, i.e., efficiency of locomotor mechanism (p < 0.001) and pelvis sagittal balance (p = 0.031) improved, while external and total work (p = 0.010) decreased post operatively. In the SBTHA group, speed (p = 0.035), step length (p = 0.046), range of motion of knee sagittal stance (p = 0.009) and hip frontal (p = 0.031), and internal work are significatively higher (p < 0.001) post operatively.

Conclusions

This original study attests that THA has a positive impact on walking and energetics outcome in UTHA and SBTHA.

Comparing early and mid-term outcomes between robotic-arm assisted and manual total hip arthroplasty: a systematic review

The projected increase in utilization rates of total hip arthroplasty (THA) has created an emphasis on novel technologies that can aid providers in maintaining historically positive outcomes. Widespread utilization of robotic assisted THA (RA-THA) is contingent upon achieving favorable outcomes compared to its traditional manual counterpart (mTHA). Therefore, the purpose of our systematic review was to compare RA-THA and mTHA in terms of the following: (1) functional outcomes and (2) complication rates. The PubMed, Embase, and Cochrane library databases were searched for articles published October 1994 and May 2021 comparing functional outcomes and complication rates between RA-THA and mTHA cohorts. When three or more studies evaluated certain PROMs and complications, a pooled analysis utilizing Mantel-Haenszel (M-H) models was conducted utilizing data from final follow-up. Our final analysis included 18 studies which reported on a total of 2811 patients [RA-THA: n = 1194 (42.48%); mTHA: n = 1617 (57.52%)]. No significant differences were demonstrated for a majority of pooled analyses and when segregating by robotic system. Only WOMAC scores were significantly lower among RA-THA patients (p = 0.0006). For outcomes without sufficient data for a pooled analysis, there were no significant differences reported among included studies. The growing utilization of RA-THA motivates comparisons to its manual counterpart. Collectively, we found comparable functional outcomes and complication profiles between RA-THA and mTHA cohorts. More randomized controlled trials of higher quality and larger sample sizes are necessary to further strengthen these findings.

Changes in 24-Hour Physical Activity Patterns and Walking Gait Biomechanics After Primary Total Hip Arthroplasty: A 2-Year Follow-up Study

BACKGROUND

Despite marked improvements in self-reported pain, perceived functional ability, and gait function following primary total hip arthroplasty (THA), it remains unclear whether these improvements translate into improved physical activity and sleep behaviors. The aim of this study was to determine the change in 24-hour activity profile (waking activities and sleep) and laboratory-based gait function from preoperatively to 2 years following the THA.

METHODS

Fifty-one patients undergoing primary THA at a single public hospital were recruited. All THAs were performed using a posterior surgical approach with the same prosthesis type. A wrist-worn accelerometer was used to capture 24-hour activity profiles preoperatively and at 1 and 2 years postoperatively. Three-dimensional gait analysis was performed to determine changes in temporospatial and kinematic parameters of the hip and pelvis.

RESULTS

Patients showed improvements in all temporospatial and kinematic parameters with time. Preoperatively, patients were sedentary or asleep for a mean time (and standard deviation) of 19.5 ± 2.2 hours per day. This remained unchanged up to 2 years postoperatively (19.6 ± 1.3 hours per day). Sleep efficiency remained suboptimal (<85%) at all time points and was worse at 2 years (77% ± 10%) compared with preoperatively (84% ± 5%). More than one-quarter of the sample were sedentary for >11 hours per day at 1 year (32%) and 2 years (41%), which was greater than the preoperative percentage (21%). Patients accumulated their activity performing light activities; however, patients performed less light activity at 2 years compared with preoperative levels. No significant differences (p = 0.935) were observed for moderate or vigorous activity across time.

CONCLUSIONS

Together with improvements in self-reported pain and perceived physical function, patients had significantly improved gait function postoperatively. However, despite the opportunity for patients to be more physically active postoperatively, patients were more sedentary, slept worse, and performed less physical activity at 2 years compared with preoperative levels.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Optimization and Validation of a Classification Algorithm for Assessment of Physical Activity in Hospitalized Patients

Low amounts of physical activity (PA) and prolonged periods of sedentary activity are common in hospitalized patients. Objective PA monitoring is needed to prevent the negative effects of inactivity, but a suitable algorithm is lacking. The aim of this study is to optimize and validate a classification algorithm that discriminates between sedentary, standing, and dynamic activities, and records postural transitions in hospitalized patients under free-living conditions. Optimization and validation in comparison to video analysis were performed in orthopedic and acutely hospitalized elderly patients with an accelerometer worn on the upper leg. Data segmentation window size (WS), amount of PA threshold (PA Th) and sensor orientation threshold (SO Th) were optimized in 25 patients, validation was performed in another 25. Sensitivity, specificity, accuracy, and (absolute) percentage error were used to assess the algorithm’s performance. Optimization resulted in the best performance with parameter settings: WS 4 s, PA Th 4.3 counts per second, SO Th 0.8 g. Validation showed that all activities were classified within acceptable limits (>80% sensitivity, specificity and accuracy, ±10% error), except for the classification of standing activity. As patients need to increase their PA and interrupt sedentary behavior, the algorithm is suitable for classifying PA in hospitalized patients.

In vivo kinematics of fixed-bearing total ankle arthroplasty

BACKGROUND

A good recovery of the physiological mobility of the ankle is an indication of patients' satisfaction after total ankle arthroplasty, which does not generally match that of other consolidated procedures such as hip and knee replacement. The aim of this study was to investigate the kinematics of the Zimmer Total Metal Total Ankle (ZTMTA) during the different exercises.

METHODS

Fifteen patients with ZTMTA were enrolled in this study. The patients performed non-weightbearing flexion-extension, stair climbing and descending, and fluoroscopic images were taken to capture the ankle movements. A combined images/three-dimensional models method was used to perform a kinematic analysis.

RESULTS

Plantar-dorsiflexion resulted the main plane of movement, with the largest range of motion (ROM) of 23.3 ± 9.0° during flexion-extension. Inversion-eversion and adduction-abduction resulted lower than 10° in any trials.

CONCLUSIONS

In the investigated population, the ZTMTA allowed a good recovery of the mobility, with ROMs comparable to the healthy subjects.

Increased Muscle Strength Limits Postural Sway During Daily Living Activities in Total Hip Arthroplasty Patients

Supplemental digital content is available in the text.

Objective

The aim of the study was to investigate the effect of maximal strength training on postural sway after total hip arthroplasty, performed before and after a battery of physical performance tests that resemble daily living activities.

Design

This study is an exploratory study based on data from a 3-mo randomized controlled trial involving 54 total hip arthroplasty patients performing maximal strength training or conventional rehabilitation. At 3, 6, and 12 mos postoperatively, postural sway was evaluated in two gait tests; ie, one test before and one test after conducting a battery of physical performance tests.

Results

At 3 mos postoperatively, postural sway in the test after was significantly higher for the conventional rehabilitation group than the maximal strength training group (P = 0.045); however, there was no between-group difference at the test before (P = 0.670). Postural sway was also significantly higher in the test after compared with the test before in the conventional rehabilitation group (P < 0.001). No difference was found between the test before and test after in the maximal strength training group (P = 0.713). At 6 and 12 mos postoperatively, there were no statistically significant within- or between-group differences in postural sway.

Conclusions

Increased muscular strength limits postural sway 3 mos postoperatively in total hip arthroplasty patients after a demanding battery of physical performance tests simulating daily living activities.

Towards an Inertial Sensor-Based Wearable Feedback System for Patients after Total Hip Arthroplasty: Validity and Applicability for Gait Classification with Gait Kinematics-Based Features

Patients after total hip arthroplasty (THA) suffer from lingering musculoskeletal restrictions. Three-dimensional (3D) gait analysis in combination with machine-learning approaches is used to detect these impairments. In this work, features from the 3D gait kinematics, spatio temporal parameters (Set 1) and joint angles (Set 2), of an inertial sensor (IMU) system are proposed as an input for a support vector machine (SVM) model, to differentiate impaired and non-impaired gait. The features were divided into two subsets. The IMU-based features were validated against an optical motion capture (OMC) system by means of 20 patients after THA and a healthy control group of 24 subjects. Then the SVM model was trained on both subsets. The validation of the IMU system-based kinematic features revealed root mean squared errors in the joint kinematics from 0.24° to 1.25°. The validity of the spatio-temporal gait parameters (STP) revealed a similarly high accuracy. The SVM models based on IMU data showed an accuracy of 87.2% (Set 1) and 97.0% (Set 2). The current work presents valid IMU-based features, employed in an SVM model for the classification of the gait of patients after THA and a healthy control. The study reveals that the features of Set 2 are more significant concerning the classification problem. The present IMU system proves its potential to provide accurate features for the incorporation in a mobile gait-feedback system for patients after THA.

Gait analysis in patients after bilateral versus unilateral total hip arthroplasty

BACKGROUND

Gait abnormalities were reported in patients after total hip arthroplasty (THA). One-stage bilateral THA was introduced for bilateral hip pathologies, showing similar clinical and surgical outcome to unilateral procedure. However, no studies analyze the gait features after bilateral THA surgery compared to unilateral THA.

RESEARCH QUESTION

Are there differences in gait characteristics between bilateral and unilateral THA patients and are there differences between these cases and asymptomatic age-matched healthy subjects?

METHODS

In this prospective observational study, thirty-five patients with bilateral (n = 18) or unilateral THA (n = 17) and twenty asymptomatic age-matched volunteers were studied. Participants underwent three-dimensional gait analysisin order to detect gait spatial-temporal and kinematic (Gait Variable Score - GVS) parameters. Mobility (Timed Up and Go - TUG), fear of movement (Tampa Scale of Kinesiophobia - TSK) and pain during walking (Numeric Rating Scale - NRS) were also assessed. Patients were evaluated the day before surgery and at seven days, whereas healthy subjects underwent a single evaluation. ANOVA was used to assess differences between the three groups at each time-point and within-group differences in bilateral and unilateral groups.

RESULTS

At baseline, no differences between the two groups of patients were found. As expected, their gait spatial-temporal and kinematic parameters and functional variables were impaired with respect to healthy subjects, both before and after surgery. After surgery, GVS Pelvic-TILT closer to normative values, longer stance and shorter swing phases were found in bilateral cases compared to unilateral patients. Moreover, a higher NRS score was found in bilateral patients, whereas TUG and TSK revealed no differences between the two groups of patients.

SIGNIFICANCE

The current findings, focusing on short-term effectiveness of bilateral THA, could assist physiotherapists in selecting the best ambulation training and an appropriate rehabilitation approach immediately after surgery.

Step Length Asymmetry and Its Associations With Mechanical Energy Exchange, Function, and Fatigue After Total Hip Replacement

Abnormalities in gait remain after total hip replacement (THR). The purpose of this study was to evaluate step length asymmetry and its links to other aspects of gait and physical function after THR and to investigate links with mechanical energy exchange. The rationale is that step length asymmetry may influence gait efficiency, which could adversely influence fatigue and physical function. We evaluated 18 participants (6 males and 12 females) 1-5 years post-THR. Step length symmetry and mechanical energy exchange were assessed by instrumented gait analysis. Fatigue was assessed using a PROMIS Fatigue Short Form. We assessed physical function using a 6-minute walk test (6MWT). We used a one sample T test to determine whether the symmetry index (SI) was significantly different from 0 and Pearson's correlations to explore associations among the variables. The step length SI was statistically significantly different from zero (p=0.01). A more symmetric step length was associated with better 6MWT (R=-0.57, p=0.03). Higher (better) mechanical energy exchange was associated with more fatigue (R=0.50, p=0.04). Mechanical energy exchange was not associated with step length SI or 6MWT. Better 6MWT was associated with less fatigue (R=-0.61, P=0.01). This suggests that the association between step length symmetry and function is not directly governed by its effect on the energy exchange. Additionally, after a relatively long period of postsurgery, participants may have adapted their gait by increasing mechanical energy exchange to minimize fatigue. Statement of Clinical Significance: A gait retraining intervention targeting step length symmetry could improve function without adversely affecting walking energetics in THR patients. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1563-1570, 2019.

ESB Clinical Biomechanics Award 2018: Muscle atrophy-related increased joint loading after total hip arthroplasty and their postoperative change from 3 to 50 months

BACKGROUND

Hip joint loading is dominated by muscular activity. Thus, contact forces exceeding many times one's body weight are a consequence of imbalanced muscular activity. The objective was to analyze the influence of muscle atrophy after total hip arthroplasty on in vivo hip joint contact loading initially and long term. We hypothesized that an impaired periarticular muscle will lead to increase in vivo joint load, specifically in the long term.

METHODS

Using a group of nine patients with instrumented hip implants, contact forces and muscle status were analyzed one day prior to 3 and 50 months after joint arthroplasty. In vivo load measurements were performed for different activities of daily living (ADL). Pre- and postoperative pelvic CT scans were analyzed to assess the periarticular muscle status. Finally, the muscle morphologies and in vivo contact forces were compared.

RESULTS

At 3 months after total hip arthroplasty we found a significant correlation of lower lean gluteus minimus muscle (GMin) volume with higher loads during all tested activities of daily living. 50 months postoperatively statistical analysis revealed lower lean volume of the gluteus maximus to be correlated with higher joint loads in walking.

CONCLUSION

Our data generally show a good comparability between muscle status and joint contact forces and thus support our hypothesis that an impairment of periarticular musculature contributes to an increase of the in vivo joint loads after total hip arthroplasty. Effects were most pronounced during stair climbing and sit-down/stand-up from a chair at 3 months and during level walking at 50 months.

Gait Training Using the Honda Walking Assistive Device® in a Patient Who Underwent Total Hip Arthroplasty: A Single-Subject Study

Background and objectives: The Honda Walking Assistive device^® (HWA) is a light and easy wearable robot device for gait training, which assists patients’ hip flexion and extension movements to guide hip joint movements during gait. However, the safety and feasibility of robot-assisted gait training after total hip arthroplasty (THA) remains unclear. Thus, we aimed to evaluate the safety and feasibility of this gait training intervention using HWA in a patient who underwent THA. Materials and methods: The patient was a 76-year-old woman with right hip osteoarthritis. Gait training using HWA was implemented for 20 sessions in total, five times per week from 1 week to 5 weeks after THA. Self-selected walking speed (SWS), step length (SL), cadence, timed up and go (TUG), range of motion (ROM) of hip extension, and hip abduction and extension torque were measured preoperatively, and at 1 (pre-HWA), 2, 3, 4, 5 (post-HWA), and 10 weeks (follow-up) after THA. The gait patterns at SWS without HWA were measured by using three-dimensional (3D) gait analysis and an integrated electromyogram (iEMG). Results: The patient completed 20 gait training sessions with no adverse event. Hip abduction torque at the operative side, hip extension torque, SWS, SL, and cadence were higher at post-HWA than at pre-HWA. In particular, SWS, TUG, and hip torque were remarkably increased 3 weeks after THA and improved to almost the same levels at follow-up. Maximum hip extension angle and hip ROM during gait were higher at post-HWA than at pre-HWA. Maximum and minimum anterior pelvic tilt angles were lower at post-HWA than at pre-HWA. The iEMG of the gluteus maximus and gluteus medius in the stance phase were lower at post-HWA than preoperatively and at pre-HWA. Conclusions: In this case, the gait training using HWA was safe and feasible, and could be effective for the early improvement of gait ability, hip function, and gait pattern after THA.

Comparison of total hip arthroplasty surgical approaches by Statistical Parametric Mapping

BACKGROUND

The most common surgical approaches in use for total hip arthroplasty are the lateral and posterior. When comparing these approaches in terms of gait biomechanics, studies usually rely on pre-defined discrete variables related to the events of gait cycle. However, this analysis may miss differences in other parts of the movement pattern that are not explored. We applied Statistical Parametric Mapping to compare hip kinematics between patients who underwent arthroplasty using either a lateral or posterior approach, contrasting these results with discrete variable analysis.

METHODS

Twenty-two participants (11 lateral, 11 posterior; age between 50 and 80 years) underwent gait analysis before, 3 weeks and 12 weeks after hip arthroplasty. One-dimensional (e.g. time-varying) trajectories and zero-dimensional (e.g. peak extension) discrete variables were used to assess differences between groups in each plane of hip movement (sagittal, frontal, and transverse).

FINDINGS

One-dimensional and zero-dimensional analyses found no significant differences between groups. Statistical Parametric Mapping revealed that both groups presented significant changes over time in hip adduction at 11-43% of the gait cycle. Zero-dimensional analysis seems to overstate sagittal plane changes over time since no such changes were found by Statistical Parametric Mapping.

INTERPRETATION

Our results agreed with previous studies suggesting that surgical approach do not affect hip kinematics at the early post-operative stage after arthroplasty. However, Statistical Parametric Mapping revealed changes in frontal plane kinematics over time that were underestimated by the zero-dimensional variables. These findings suggest hip adduction impairment up to 12 weeks after arthroplasty.

Gluteal muscle damage leads to higher in vivo hip joint loads 3 months after total hip arthroplasty

Background

Total hip arthroplasty (THA) is in most cases improving patients´ life quality immediately after surgery. However, a closer look at these patients, especially with modern gait analysis methods, reveals also negative consequences due to the surgical approach related injury to the pelvic muscles. We hypothesized that this damage will have a negative impact on hip joint contact forces during activities of daily living (ADL).

Methods

10 patients undergoing THA received an instrumented hip joint implant enabling real time in vivo measurements of hip joint loads using a direct lateral approach. Pre- and 3 months postoperative computed tomography (CT) scans were used for evaluation of the periarticular muscle status, using muscle volume, fat ratio and lean muscle volume as parameters. An analysis of in vivo hip contact forces was made 3 months after THA during ADL (walking, stair climbing, chair rising and sitting) and correlated with the morphology of the periarticular muscles.

Results

We found a significant decrease of volume by 25% (-3 to -45, p = 0.005) and increase in fat ratio of the Gluteus Minimus (Gmin), resulting in a decrease in lean muscle volume of 28% (-48 to 0, p = 0.008). This was accompanied by an inverse development in the Tensor Fasciae Latae (TFL) resulting in a lean muscle volume increase of 34% (-2 to -102, p = 0.013). Changes in Gluteus Medius (Gmed) and Gluteus Maximus (Gmax) have not been observed in the short-term follow up. A decreased Gmin lean muscle volume was found to strongly correlate with high in vivo joint contact forces in all tested ADL.

Conclusion

The decrease of Gmin volume can be seen as a direct effect of THA surgery, whereas the increase of TFL might compensate for loss of Gmin volume. Lean muscle volume and fat ratio were better predictors for joint contact forces than total muscle volume. These effects were most pronounced during sitting down and standing up due to the higher demand on the gluteal muscles during these activities.