Minimizing preoperative and postoperative limping in patients after total hip arthroplasty: relevance of hip muscle strength and endurance

Reliability of the Harris Hip limping sub-score in patients undergoing total hip arthroplasty

PURPOSE

In patients undergoing total hip arthroplasty, limping is a significant symptom, often assessed with the limping sub-score of the Harris Hip Score. However, the reliability of this sub-score has not been specifically investigated. The purpose of this study is to investigate the intra- and inter-rater reliability of this sub-score.

METHODS

Thirty patients undergoing THA were recruited and performed a gait analysis before surgery and three months after surgery. In addition, 30 asymptomatic participants were included. In total, 90 visits were analysed in this study. The HHS limping sub-score was assessed for each visit using a video (front and back view side-by-side) of a ten metre walk at a self-selected speed. Two orthopaedic surgeons evaluated the limping of each video in two different grading sessions with a one week delay. To avoid recall bias, the patient's number identity was randomized and different for each grading session and each rater. The weighted Cohen's Kappa coefficient was used to quantify the intra- and inter-reliability. The reliability of three components was studied: the presence of limping, its severity, and the compensation type.

RESULTS

For all components, the agreement for intra-rater reliability ranged from moderate to strong and from none to moderate for the inter-rater reliability.

CONCLUSION

These results do not encourage the use of HHS-limping sub-score for data involving different raters in both clinical and research contexts. It calls for improved consensus on limping definitions or the creation of objective measures.

A Monocortical Screw for Preventing Trochanteric Escape in Extended Trochanteric Osteotomy: A Simple Solution to a Complicated Problem?

Extended trochanteric osteotomy (ETO) is an established method in revision total hip arthroplasty. Proximal migration of the greater trochanter fragment and the resulting non-union of the osteotomy remains a major problem, and several techniques have been developed to prevent its occurrence. This paper describes a novel modification of the original surgical technique in which a single monocortical screw is placed distally to one of the cerclages used for the fixation of the ETO. The contact between the screw and the cerclage counteracts the forces applied on the greater trochanter fragment and prevents trochanteric escape under the cerclage. The technique is simple and minimally invasive, does not require special skills or additional resources, or add to surgical trauma or operating time, and therefore represents a simple solution to a complicated problem.

Comparison of Functional and Radiographic Outcomes Between Two Fixation Methods for Extended Trochanteric Osteotomy in Revision Total Hip Arthroplasty: A Retrospective Cohort Study

BACKGROUND

To compare the functional and radiographic outcomes between two fixation methods for extended trochanteric osteotomy (ETO) in revision total hip arthroplasty (rTHA).

METHODS

Included in this study were 64 patients who underwent ETO in rTHA using either claw-plate fixation (claw-plate group, n = 31) or cable-alone fixation (cable group, n = 33) in our hospital from 2008 to 2020. The functional and radiographic results and complications were compared between the groups during a mean follow-up period of 64 and 78 months.

RESULTS

The Harris hip score and visual analogue scale at the last follow-up improved significantly in both groups, showing no significant statistical difference between the two fixation methods. In the cable group, the mean abductor lever arm, the proximal migration, and medial migration in the affected hip were significantly decreased compared to those in the contralateral normal hip (P < .05), whereas in the claw-plate group no significant statistical differences were observed between two sides. No or slight limping occurred in 25 patients (81%) in the claw-plate group and 16 patients (48%) in the cable group (P = .007). A multiple logistic regression demonstrated that claw-plate fixation could reduce the incidence of postoperative moderate-to-severe limping.

CONCLUSION

Both claw-plate fixation and cable-alone fixation could improve the functional performance of rTHA with ETO, whereas claw-plate fixation could offer superior biomechanical results and gait improvement as compared with cable-alone fixation.

Gait function improvements, using Cardiff Classifier, are related to patient-reported function and pain following hip arthroplasty

Summarizing results of three-dimensional (3D) gait analysis into a comprehensive measure of overall gait function is valuable to discern to what extent gait function is affected, and later recovered after surgery and rehabilitation. This study aimed to investigate whether preoperative gait function, quantified and summarized using the Cardiff Classifier, can predict improvements in postoperative patient-reported activities of daily living, and overall gait function 1 year after total hip arthroplasty (THA). Secondly, to explore relationships between pre-to-post surgical change in gait function versus changes in patient-reported and performance-based function. Thirty-two patients scheduled for THA and 25 nonpathological individuals were included in this prospective cohort study. Patients were evaluated before THA and 1 year postoperatively using 3D gait analysis, patient-reported outcomes, and performance-based tests. Kinematic and kinetic gait parameters, derived from 3D gait analysis, were quantified using the Cardiff Classifier. Linear regressions investigated the predictive value of preoperative gait function on postoperative outcomes of function, and univariate correlations explored relationships between pre-to-post surgical changes in outcome measures. Preoperative gait function, by means of Cardiff Classifier, explained 35% and 30% of the total variance in change in patient-reported activities of daily living, and in gait function, respectively. Moderate-to-strong correlations were found between change in gait function and change in patient-reported function and pain, while no correlations were found between change in gait function and performance-based function. Clinical significance: Preoperative gait function predicts postsurgical function to a moderate degree, while improvements in gait function after surgery are more closely related to how patients perceive function than their maximal performance of functional tests.

Abductor Muscle Strength Deficit in Patients After Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

The aims of this study were to assess and quantify hip abductor muscle strength deficits after total hip arthroplasty (THA) and to determine associations with external factors.

METHODS

Studies reporting on hip abductor muscle strength before and/or after THA performed for osteoarthritis or atraumatic osteonecrosis of the hip were considered for inclusion. Data sources were Embase, Medline, and the Cochrane Central Register of Controlled Trials. Muscle strength on the affected side was compared with the healthy contralateral side or with control subjects. Study quality was assessed using a modified Newcastle-Ottawa Scale.

RESULTS

Nineteen studies reporting on 875 subjects met the inclusion criteria. Patients scheduled for THA had a mean strength deficit of 18.6% (95% confidence interval (CI) [-33.9, -3.2%]) compared with control subjects. Abductor muscle strength then increased by 20.2% (CI [5.6, 34.8%]) at 4-6 months, 29.6% (CI [4.7, 54.4%]) at 9-12 months, and 49.8% (CI [-31.0, 130.6%]) at 18-24 months postoperatively compared with preoperative values. For unilateral THA, the mean torque ratio was 86.3% (CI [75.4, 97.2%]) and 93.4% (CI [75.1, 111.6%]) before and >24 months after THA, respectively. Study quality was low to moderate.

CONCLUSION

Hip abductor muscle strength deficits may gradually improve during 24 months after THA possibly without complete recovery. Cautious interpretation of these findings is warranted because high-quality evidence is largely missing.

Early Maximal Strength Training Improves Leg Strength and Postural Stability in Elderly Following Hip Fracture Surgery

Introduction:

Hip fractures predominantly occur in the geriatric population and results in increased physical inactivity and reduced independency, largely influenced by a downward spiral of ambulatory capacity, related to loss of skeletal muscle strength and postural stability. Thus, effective postoperative treatment, targeting improvements in muscle strength, is sought after.

Materials & Methods:

Twenty-one hip fracture patients (>65 yr) were randomized to 8 weeks of either conventional physiotherapy control group (CG), or leg press and hip abduction maximal strength training (MST) 3 times per week. MST was performed applying heavy loads (85-90% of 1 repetition maximum; 1RM) and 4-5 repetitions in 4 sets. Maximal strength (bi- and unilateral 1RM), postural stability (unipedal stance test; UPS), and DEXA-scan bone mineral content/ density (BMC/BMD) were measured before and after the 8-week rehabilitation.

Results:

Both MST and conventional physiotherapy improved bilateral leg press 1RM by 41 ± 27 kg and 29 ± 17 kg, respectively (both p < 0.01), while unilateral leg press 1RM only increased after MST (within group and between groups difference: both p < 0.05). MST also resulted in an increase in abduction 1RM in both the fractured (5 kg, 95%CI: 2-7; p < 0.01) and healthy limb (6 kg, 95%CI: 3-9; p < 0.01), while no such improvement was apparent in the CG (between groups difference: p < 0.01). Finally, MST improved UPS of the fractured limb (p < 0.05). No differences were observed in BMC or BMD following the 8 weeks.

Discussion:

Early postoperative MST improved lower extremities maximal muscle strength more than conventional physiotherapy and was accompanied by improvements in postural stability.

Conclusion:

Implementing MST in early rehabilitation after hip fracture surgery should be considered as a relevant treatment to curtail the downward spiral of reduced ambulatory capacity typical for this patient group, possibly reducing the risk of recuring falls and excess mortality.

Trial Registration:

https://clinicaltrials.gov/ct2/show/NCT03030092

Abductor muscle strength deficit in patients after total hip arthroplasty for hip osteoarthritis: a protocol for a systematic review and meta-analysis

INTRODUCTION

Conservation of abductor muscle strength is directly associated with physical function after total hip replacement (THA). Although many studies have tried to explore and quantify a potential abductor muscle strength deficit after THA as well as identify possible causes and treatment options, this topic has not been addressed systematically.

METHODS AND ANALYSIS

Human-based studies reporting measurements of hip abductor strength will be included in this review. Studies reporting on hip abductor strength measured manually or isometric measurements at an abduction angle other than 0° will not be considered. No restriction will be placed on study design, publication date operative approach, prosthesis design, age and sex of the patients or severity of OA. Data sources will be Embase via embase.com, Medline ALL via Ovid and the Cochrane Central Register of Controlled Trials. The preliminary search was conducted on 5 May 2019. Data regarding absolute values or torque ratio of hip abductor torque between sides as well as patient demographic data, surgical approaches and rehabilitation protocols will be extracted. The assessment of quality and risk of bias will be performed with the modified Newcastle-Ottawa Scale. The screening, data extraction and quality assessment will be performed by two reviewers independently. Where necessary, a third review author will make a final judgement. Narrative synthesis as well as tabular presentation of the extracted data will be included. Whenever possible, metaregression and subgroup specific meta-analyses will be used to investigate the influence of time since THA and type of measurement (isokinetic or isometric) on the different outcomes. In case of sufficient information, these analyses will be extended to include characteristics such as age, sex, surgical approach or rehabilitation programme.

ETHICS AND DISSEMINATION

No ethics approval is required. The results will be disseminated through peer-reviewed publications and conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42020153185.

Incidence and Risk Factors for Falls in Women With End-Stage Hip Osteoarthritis

BACKGROUND AND PURPOSE

Fall-induced injuries and resulting deaths are a serious health problem among older adults. The most common risk factors for falls in older adults are muscle weakness, gait deficiencies, and balance deficits. Patients with end-stage hip osteoarthritis (OA) also have many hip dysfunctions, and these all have the potential to increase the risk of falls. However, the incidence and risk factors for falls in patients with end-stage hip OA remain unclear. The aim of this study was to determine the incidence of falls in women with end-stage hip OA and to identify risk factors for falls in this patient population.

METHODS

This study was a cross-sectional analysis. One hundred fifty-three women with end-stage hip OA (mean age = 64.0 years) and 112 age-matched healthy women (mean age = 64.1 years) were analyzed using available data. All participants were examined for the number and circumstances of falls in the past year. The circumstances of falls included the location, time, direction, cause, and injury. We examined the outcome of hip function, ambulatory ability, physical activity, and limping severity in women with end-stage hip OA. Multivariate logistic regression analysis was used to identify factors influencing falls in women with hip OA.

RESULTS

The incidence of at least 1 fall in the past year was significantly higher in women with end-stage hip OA (30.1%) than in healthy women (12.5%) (P < .001). Falls in women with end-stage hip OA were most often caused by tripping and falling forward during the daytime. The majority of falls (65.2%) resulted in injuries and 13.0% resulted in fractures. The occurrence of a fall significantly correlated with limping (odds ratio = 3.26, 95% confidence interval = 1.49-7.14, P = .003) and knee extensor muscle strength (odds ratio = 0.22, 95% confidence interval = 0.05-0.85, P = .029).

CONCLUSIONS

Women with end-stage hip OA have an increased risk of falls and fall-induced injuries. The prevention of falls in this vulnerable population should be a priority among health care practitioners. In particular, women who are limping and have reduced lower knee extensor strength should take care to avoid falls.

Magnetic Resonance Imaging Assessment of Hip Abductor after Total Hip Arthroplasty Using a Direct Lateral Approach

Background

Surgical techniques and rehabilitations after total hip arthroplasty (THA) play a significant role in the improvement of pain and limping. This study aimed to assess hip abductor muscle's diameter and its strength after 6 months postoperative THA performed by Hardinge approach.

Methods

After obtaining the patients' demographic characteristics, the preoperative values of patients' hip abductor muscle diameter were measured using magnetic resonance imaging, and were compared with postoperative values 6 months later. Moreover, the hip abductor muscle's strength was assessed using the Trendelenburg test.

Results

A total of 88 patients participated in this study with a mean age of 47.3±1.574 years. It should be noted that 55.7% of the participants were male. Muscle diameter decreased from a mean value of 27.07±7.485 preoperative to mean value of 25.64±7.353 mm postoperative (P<0.001). Moreover, the degrees of Trendelenburg test (i.e., mild or severe) decreased after surgery (P<0.001). There was no significant difference between the frequencies of different grades of limping according to the studied variables.

Conclusion

A decrease was observed in gluteus medius muscle diameter, and the Trendelenburg test results were improved in this study. Moreover, the difference between pre- and postoperative gluteus medius muscle diameters were measured using MRI. It can be concluded that MRI is not an appropriate diagnostic tool for the assessment of abductor strength after THA in the 6-month postoperative visit. Accordingly, it is suggested to evaluate muscle strength before and after each surgery to schedule the following treatment protocol required for each patient.

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.

Gait Abnormality Predicts Falls in Women After Total Hip Arthroplasty

BACKGROUND

Patients who undergo total hip arthroplasty (THA) have an increased risk of falls during the first year postoperatively. However, risk factors for falls after THA remain unclear. We investigated the relationship between gait abnormality and falls during the first year after THA.

METHODS

We conducted a prospective cohort study of 286 patients with severe hip osteoarthritis who underwent THA and examined fall history during the first year postoperatively. Baseline characteristics including age, body mass index, number of prescribed medications, comorbidities, and history of falling in the past year were evaluated as covariates and determined using a self-administered questionnaire and interview preoperatively. We assessed functional outcomes, including passive range of motion of the hip joint (flexion, extension, abduction, and adduction), muscle strength (hip abduction and knee extension), gait velocity, and gait abnormality, at 3 weeks postoperatively. Cox proportional hazard regression models were used to analyze the relationship between the presence of gait abnormality and falls.

RESULTS

One hundred sixty-two women were included. The incidence of at least 1 fall during the first year after THA was 31.5%. Cox proportional hazard regression models showed that the presence of gait abnormality (hazard ratio, 2.91; 95% confidence interval, 1.55-5.48; P < .001) was significantly associated with falls during the first year postoperatively.

CONCLUSION

The presence of gait abnormality is a useful screening tool to predict future falls in women after THA. Clinicians should assess gait abnormality to identify patients who may require fall prevention measures and continuous rehabilitation to improve gait abnormality.

A randomized controlled trial on maximal strength training in 60 patients undergoing total hip arthroplasty

Background and purpose - Total hip arthroplasty (THA) patients have reduced muscle strength after rehabilitation. In a previous efficacy trial, 4 weeks' early supervised maximal strength training (MST) increased muscle strength in unilateral THA patients <65 years. We have now evaluated muscle strength in an MST and in a conventional physiotherapy (CP) group after rehabilitation in regular clinical practice. Patients and methods - 60 primary THA patients were randomized to MST or CP between August 2015 and February 2016. The MST group trained at 85-90% of their maximal capacity in leg press and abduction of the operated leg (4 × 5 repetitions), 3 times a week at a municipal physiotherapy institute up to 3 months postoperatively. The CP group followed a training program designed by their respective physiotherapist, mainly exercises performed with low or no external loads. Patients were tested pre- 3, 6, and 12 months postoperatively. Primary outcomes were abduction and leg press strength at 3 months. Other parameters evaluated were pain, 6-min walk test, Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) Physical Function Short-form score. Results - 27 patients in each group completed the intervention. MST patients were substantially stronger in leg press and abduction than CP patients 3 (43 kg and 3 kg respectively) and 6 months (30 kg and 3 kg respectively) postoperatively (p ≤ 0.002). 1 year postoperatively, no intergroup differences were found. No other statistically significant intergroup differences were found. Interpretation - MST increases muscle strength more than CP in THA patients up to 6 months postoperatively, after 3 months' rehabilitation in clinical practice. It was well tolerated by the THA patients and seems feasible to conduct within regular clinical practice.

Preoperative gluteus medius muscle atrophy as a predictor of walking ability after total hip arthroplasty

PURPOSE

To elucidate the relation between certain preoperative physical parameters and walking with a limp after total hip arthroplasty (THA) and determine whether it is possible to predict the walking ability of patients 6 months after THA.

METHODS

The subjects of this study comprised 74 female patients who had undergone unilateral THA. Before surgery, the hip abductor and knee extensor strengths were measured, the cross-sectional areas (CSAs) of the gluteus medius and rectus abdominis muscles were measured, and the Timed Up and Go test was conducted. The patients were then divided into two groups according to gait observation results 6 months postoperatively: walking without a limp (n=37) and walking with a limp (n=37).

RESULTS

The discriminating criteria between the two groups were age (61 years), CSA of the gluteus medius muscle (2000 mm2), and CSA of the rectus abdominis muscle (340 mm2). In the multiple logistic regression analysis, the gluteus medius muscle was the only significant predictor of limping after THA (β=1.64, R2=0.19, p<0.01).

CONCLUSIONS

The results of the present study suggest that preoperative atrophy of the gluteus medius is an useful indicator for predicting walking with a limp 6 months postoperatively.

The Gait Deviation Index Is Associated with Hip Muscle Strength and Patient-Reported Outcome in Patients with Severe Hip Osteoarthritis-A Cross-Sectional Study

Background

The Gait Deviation Index summarizes overall gait ‘quality’, based on kinematic data from a 3-dimensional gait analysis. However, it is unknown which clinical outcomes may affect the Gait Deviation Index in patients with primary hip osteoarthritis. The aim of this study was to investigate associations between Gait Deviation Index as a measure of gait ‘quality’ and hip muscle strength and between Gait Deviation Index and patient-reported outcomes in patients with primary hip osteoarthritis.

Method

Forty-seven patients (34 males), aged 61.1 ± 6.7 years, with BMI 27.3 ± 3.4 (kg/m²) and with severe primary hip osteoarthritis underwent 3-dimensional gait analysis. Mean Gait Deviation Index, pain after walking and maximal isometric hip muscle strength (flexor, extensor, and abductor) were recorded. All patients completed the ‘Physical Function Short-form of the Hip disability and Osteoarthritis Outcome Score (HOOS-Physical Function) and the Hip disability and Osteoarthritis Outcome Score subscales for pain (HOOS-Pain) and quality-of-life (HOOS-QOL).

Results

Mean Gait Deviation Index was positively associated with hip abduction strength (p<0.01, r = 0.40), hip flexion strength (p = 0.01, r = 0.37), HOOS-Physical Function (p<0.01, r = 0.41) HOOS-QOL (p<0.01, r = 0.41), and negatively associated with HOOS-Pain after walking (p<0.01, r = -0.45). Adjusting the analysis for walking speed did not affect the association.

Conclusion

Patients with the strongest hip abductor and hip flexor muscles had the best gait ‘quality’. Furthermore, patients with higher physical function, quality of life scores and lower pain levels demonstrated better gait ‘quality’. These findings indicate that interventions aimed at improving hip muscle strength and pain management may to a moderate degree improve the overall gait ‘quality’ in patients with primary hip OA.

Current Concepts in Hip Preservation Surgery: Part II--Rehabilitation

CONTEXT

Successful treatment of nonarthritic hip pain in young athletic individuals remains a challenge. A growing fund of clinical knowledge has paralleled technical innovations that have enabled hip preservation surgeons to address a multitude of structural variations of the proximal femur and acetabulum and concomitant intra-articular joint pathology. Often, a combination of open and arthroscopic techniques are necessary to treat more complex pathomorphologies. Peri- and postoperative recovery after such procedures can pose a substantial challenge to the patient, and a dedicated, thoughtful approach may reduce setbacks, limit morbidity, and help optimize functional outcomes.

EVIDENCE ACQUISITION

PubMed and CINAHL databases were searched to identify relevant scientific and review articles through December 2014 using the search terms hip preservation, labrum, surgical dislocation, femoroacetabular impingement, postoperative rehabilitation, peri-acetabular osteotomy, and rotational osteotomy. Reference lists of included articles were reviewed to locate additional references of interest.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Hip preservation procedures and appropriate rehabilitation have allowed individuals to return to a physically active lifestyle.

CONCLUSION

Effective postoperative rehabilitation must consider modifications and precautions specific to the particular surgical techniques used. Proper postoperative rehabilitation after hip preservation surgery may help optimize functional recovery and maximize clinical success and patient satisfaction.

Relationship of unilateral total hip arthroplasty (THA) to contralateral and ipsilateral knee joint degeneration - a longitudinal 3T MRI study from the Osteoarthritis Initiative (OAI)

OBJECTIVE

To evaluate the association of prevalent unilateral total hip arthroplasty (THA) with worsening of degenerative knee abnormalities and clinical outcomes in the ipsilateral and contralateral knee.

METHODS

Both knees of 30 individuals in the Osteoarthritis Initiative (OAI) with unilateral THA (n = 14 left, n = 16 right) at baseline were assessed at baseline and at 4-year follow-up for Whole-organ MR Imaging Scores (WORMS), cartilage T2 relaxation times (only available for right knees), Western Ontario and McMasters Universities Arthritis Index (WOMAC) scores and upper leg isometric strength. Right knees of 30 individuals without THA were analyzed as controls. Contralateral knees were compared to ipsilateral knees with paired t-tests and to control knees with multivariate regression analysis adjusting for covariates.

RESULTS

In paired analyses, compared to ipsilateral knees, contralateral knees had higher WORMS total (P = 0.008) and cartilage scores (P = 0.007) at baseline. Over 4 years contralateral knees worsened more on WORMS total score (P = 0.008). Cartilage T2 values were higher in knees contralateral to the THA (baseline, P = 0.02; follow-up, P < 0.001). Contralateral knees had greater declines in knee extension strength (P = 0.04) and had a trend for greater worsening in WOMAC pain, stiffness, function and total scores (P = 0.04-0.09). Similar results were found comparing contralateral knees with control knees in multivariate regression models.

CONCLUSIONS

Prevalent unilateral THA is associated with an greater progression of degenerative findings for the knee contralateral to THA.

Changes in gait patterns and muscle activity following total hip arthroplasty: a six-month follow-up

BACKGROUND

Appropriate gait function is an important determinant of the outcome of total hip arthroplasty and relies on appropriate joint motion and muscle activity. The purpose of this study was to test the hypothesis that 6-month postoperative dynamic joint range of motion, time-distance measures and muscle activity in the operated limb in patients undergoing total hip arthroplasty differ from preoperative levels and are more similar to those observed postoperatively in the contralateral limb and in healthy subjects.

METHODS

Basic time-distance gait measurements, knee and hip kinematics and electromyographic activity from eight hip muscles were obtained preoperatively and 6 months postoperatively in 52 patients undergoing total hip arthroplasty and in 24 age-matched healthy subjects during treadmill walking.

FINDINGS

Postoperative dynamic hip range of motion for the operated limb (confidence interval differences [-3.9°; -2.3°]) and postoperative knee range of motion for both limbs (operated: [-8.4°; -5.6°]; contralateral: [-8.1°; -5.3°]) in patients with total hip arthroplasty were significantly lower than values for the control subjects (P<0.001). Postoperative gait in patients with total hip arthroplasty was more symmetric than preoperative gait. Preoperative and postoperative electromyographic intensities were higher in patients with total hip arthroplasty than values for the control subjects (P<0.001), and patients had different EMG patterns compared to the control group.

INTERPRETATION

Pre- and postoperative differences not only in hip but also in knee kinematics emphasize the importance of evaluating the dynamic outcome of total hip arthroplasty by assessing joint motion of all lower extremity joints in both legs.