Time course and extent of functional recovery during the first postoperative year after minimally invasive total hip arthroplasty with two different surgical approaches—a randomized controlled trial

Do 3-dimensional Spinopelvic Characteristics Normalize After THA? A Prospective, Comparative Study Using Motion Capture Analysis

BACKGROUND

Spinopelvic stiffness (primarily in the sagittal plane) has been identified as a factor associated with inferior patient-reported outcomes (PROs) and increased dislocation risk after THA. Incorporating preoperative spinopelvic characteristics into surgical planning has been suggested to determine a patient-specific cup orientation that minimizes dislocation risk. Sagittal plane radiographic analysis of static postures indicates that patients exhibit a degree of normalization in their spinopelvic characteristics after THA. It is not yet known whether normalization is also evident during dynamic movement patterns, nor whether it occurs in the coronal and axial planes as well.

QUESTIONS/PURPOSES

(1) Does motion capture analysis of sagittal spinopelvic motion provide evidence of normalization after THA? (2) Do changes in coronal and axial plane motion accompany those in the sagittal plane?

METHODS

Between April 2019 and February 2020, 25 patients agreed to undergo motion capture movement analysis before THA for the treatment of hip osteoarthritis (OA). Of those, 20 underwent the same assessment between 8 and 31 months after THA. Five patients were excluded because of revision surgery (n = 1), contralateral hip OA (n = 1), and technical issues with a force plate during post-THA assessment (n = 3), leaving a cohort total of 15 (median age [IQR] 65 years [10]; seven male and eight female patients). A convenience sample of nine asymptomatic volunteers, who were free of hip and spinal pathology, was also assessed (median age 51 years [34]; four male and five female patients). Although the patients in the control group were younger than those in the patient group, this set a high bar for our threshold of spinopelvic normalization, reducing the possibility of false positive results. Three-dimensional motion capture was performed to measure spinal, pelvic, and hip motion while participants completed three tasks: seated bend and reach, seated trunk rotation, and gait on a level surface. ROM during each task was assessed and compared between pre- and post-THA conditions and between patients and controls. Statistical parametric mapping (SPM) was used to assess the timing of differences in motion during gait, and spatiotemporal gait parameters were also measured.

RESULTS

After THA, patients demonstrated improvements in sagittal spinal (median [IQR] 32° [18°] versus 41° [14°]; difference of medians 9°; p = 0.004), pelvis (25° [21°] versus 30° [8°]; difference of medians 5°; p = 0.02), and hip ROM (21° [18°] versus 27° [10°]; difference of medians 6°; p = 0.02) during seated bend and reach as well in sagittal hip ROM during gait (30° [11°] versus 44° [7°]; difference of medians 14°; p < 0.001) compared with their pre-THA results, and they showed a high degree of normalization overall. These sagittal plane changes were accompanied by post-THA increases in coronal hip ROM (12° [9°] versus 18° [8°]; difference of medians 6°; p = 0.01) during seated trunk rotation, by both coronal (6° [4°] versus 9° [3°]; difference of medians 3°; p = 0.01) and axial (10° [8°] versus 16° [7°]; difference of medians 6°; p = 0.003) spinal ROM, as well as coronal (8° [3°] versus 13° [4°]; difference of medians 5°; p < 0.001) and axial hip ROM (21° [11°] versus 34° [24°]; difference of medians 13°; p = 0.01) during gait compared with before THA. The SPM analysis showed these improvements occurred during the late swing and early stance phases of gait.

CONCLUSION

When restricted preoperatively, spinopelvic characteristics during daily tasks show normalization after THA, concurring with previous radiographic findings in the sagittal plane. Thus, spinopelvic characteristics change dynamically, and incorporating them into surgical planning would require predictive models on post-THA improvements to be of use.

LEVEL OF EVIDENCE

Level II, prognostic study.

Functional assessment in patients undergoing total hip arthroplasty

Aims

Conventional patient-reported surveys, used for patients undergoing total hip arthroplasty (THA), are limited by subjectivity and recall bias. Objective functional evaluation, such as gait analysis, to delineate a patient's functional capacity and customize surgical interventions, may address these shortcomings. This systematic review endeavours to investigate the application of objective functional assessments in appraising individuals undergoing THA.

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied. Eligible studies of THA patients that conducted at least one type of objective functional assessment both pre- and postoperatively were identified through Embase, Medline/PubMed, and Cochrane Central database-searching from inception to 15 September 2023. The assessments included were subgrouped for analysis: gait analysis, motion analysis, wearables, and strength tests.

Results

A total of 130 studies using 15 distinct objective functional assessment methods (FAMs) were identified. The most frequently used method was instrumented gait/motion analysis, followed by the Timed-Up-and-Go test (TUG), 6 minute walk test, timed stair climbing test, and various strength tests. These assessments were characterized by their diagnostic precision and applicability to daily activities. Wearables were frequently used, offering cost-effectiveness and remote monitoring benefits. However, their accuracy and potential discomfort for patients must be considered.

Conclusion

The integration of objective functional assessments in THA presents promise as a progress-tracking modality for improving patient outcomes. Gait analysis and the TUG, along with advancing wearable sensor technology, have the potential to enhance patient care, surgical planning, and rehabilitation.

Incorporating Functional Strength Integration Techniques During Total Hip Arthroplasty Rehabilitation: A Randomized Controlled Trial

OBJECTIVE

Total hip arthroplasty (THA) is a common orthopedic procedure that alleviates pain for millions of individuals. Yet, persistent physical function deficits, perhaps associated with movement compensations, are observed after THA. These deficits negatively affect quality of life and health for many individuals. Functional strength integration (FSI) techniques combine muscle strength training with specific movement retraining to improve physical function. This study aimed to determine if FSI would improve functional performance through remediation of movement compensations for individuals after THA.

METHODS

A double-blind randomized controlled trial was conducted. Ninety-five participants were randomized to either the FSI or control (CON) group for an 8-week intervention. The FSI protocol included exercise to improve muscular control and stability around the hip to minimize movement compensation during daily activity. The CON protocol included low-load resistance exercise, range-of-motion activities, and patient education. Functional performance, muscle strength, and self-reported outcomes were measured preoperatively, midway and after intervention, and 6 months after THA. Change from preoperative assessment to each time point was measured, and between-group differences were assessed.

RESULTS

There were minimal differences in outcomes between groups at the first postoperative assessment. There were no statistically significant between-group differences in the later assessments, including the primary endpoint. Both groups improved functional outcomes throughout the study period.

CONCLUSION

The FSI intervention did not result in greater improvements in function after THA compared to the CON intervention. Future work should further investigate additional biomechanical outcomes, timing of the FSI protocol, effective dosing, and patient characteristics predictive of success with FSI.

IMPACT

Recovery after THA is complex, and individuals after THA are affected by persistent movement deficits that affect morbidity and quality of life. The present study suggests that either approach to THA rehabilitation could improve outcomes for patients, and that structured rehabilitation programs may benefit individuals after THA.

Effects of hip osteoarthritis on lower body joint kinematics during locomotion tasks: a systematic review and meta-analysis

Introduction

Motion analysis can be used to gain information needed for disease diagnosis as well as for the design and evaluation of intervention strategies in patients with hip osteoarthritis (HOA). Thereby, joint kinematics might be of great interest due to their discriminative capacity and accessibility, especially with regard to the growing usage of wearable sensors for motion analysis. So far, no comprehensive literature review on lower limb joint kinematics of patients with HOA exists. Thus, the aim of this systematic review and meta-analysis was to synthesise existing literature on lower body joint kinematics of persons with HOA compared to those of healthy controls during locomotion tasks.

Methods

Three databases were searched for studies on pelvis, hip, knee and ankle kinematics in subjects with HOA compared to healthy controls during locomotion tasks. Standardised mean differences were calculated and pooled using a random-effects model. Where possible, subgroup analyses were conducted. Risk of bias was assessed with the Downs and Black checklist.

Results and Discussion

A total of 47 reports from 35 individual studies were included in this review. Most studies analysed walking and only a few studies analysed stair walking or turning while walking. Most group differences were found in ipsi- and contralateral three-dimensional hip and sagittal knee angles with reduced ranges of motion in HOA subjects. Differences between subjects with mild to moderate and severe HOA were found, with larger effects in severe HOA subjects. Additionally, stair walking and turning while walking might be promising extensions in clinical gait analysis due to their elevated requirements for joint mobility. Large between-study heterogeneity was observed, and future studies have to clarify the effects of OA severity, laterality, age, gender, study design and movement execution on lower limb joint kinematics.

Systematic Review Registration

PROSPERO (CRD42021238237).

Sleep Disturbance Trends in the Short-Term Postoperative Period for Patients Undergoing Total Joint Arthroplasty

BACKGROUND

Patients undergoing total joint arthroplasty (TJA) often experience preoperative/postoperative sleep disturbances. Although sleep quality generally improves > 6 months after surgery, patterns of sleep in the short-term postoperative period are poorly understood. This study sought to (1) characterize sleep disturbance patterns over the 3-month postoperative period and (2) investigate clinical and sociodemographic factors associated with 3-month changes in sleep.

METHODS

This retrospective analysis of prospectively collected data included 104 primary elective TJA patients. Patients were administered the PROMIS Sleep Disturbance questionnaire preoperatively and at 2 weeks, 6 weeks, and 3 months postoperatively. Median sleep scores were compared between time points using Wilcoxon signed-rank tests, stratified by preoperative sleep impairment. A multivariable logistic regression model identified factors associated with 3-month clinically improved sleep.

RESULTS

The percentage of patients reporting sleep within normal limits increased over time: 54.8% preoperatively and 58.0%, 62.5%, and 71.8% at 2 weeks, 6 weeks, and 3 months post-TJA, respectively. Patients with normal preoperative sleep experienced a transient 4.7-point worsening of sleep at 2 weeks ( P = 0.003). For patients with moderate/severe preoperative sleep impairment, sleep significantly improved by 5.4 points at 2 weeks ( P = 0.002), with improvement sustained at 3 months. In multivariable analysis, patients undergoing total hip arthroplasty (versus knee; OR: 3.47, 95% CI: 1.06 to 11.32, P = 0.039) and those with worse preoperative sleep scores (OR: 1.13, 95% CI: 1.04 to 1.23, P = 0.003) were more likely to achieve clinically improved sleep from preoperatively to 3 months postoperatively.

DISCUSSION

Patients experience differing patterns in postoperative sleep changes based on preoperative sleep disturbance. Hip arthroplasty patients are also more likely to experience clinically improved sleep by 3 months compared with knee arthroplasty patients. These results may be used to counsel patients on postoperative expectations and identify patients at greater risk of impaired postoperative sleep.

STUDY DESIGN

Retrospective analysis of prospectively collected data.

Functional assessment of total hip arthroplasty using inertial measurement units: Improvement in gait kinematics and association with patient-reported outcome measures

Inertial measurement units (IMUs) are commonly used for gait assessment, yet their potential for quantifying improvements in gait function and patterns after total hip arthroplasty (THA) has not been fully explored. The primary aim of this study was to compare spatiotemporal parameters and sagittal plane kinematic patterns of patients with hip osteoarthritis (OA) before and after THA, and to asymptomatic controls. The secondary aim was to assess the association between dynamic hip range of motion (ROM) during walking and the Hip Osteoarthritis Outcome Scores (HOOS). Twenty-four patients with hip OA and 24 matched asymptomatic controls completed gait analyses using the RehaGait® sensor system. Patients were evaluated pre- and 1 year postoperatively, controls in a single visit. Differences in kinematic data were analyzed using statistical parametric mapping, and correlations between dynamic hip ROM and HOOS were calculated. Walking speed and stride length significantly increased (+0.08 m/s, p = 0.019; +0.06 m, p = 0.048) after THA but did not reach the level of asymptomatic controls (-0.11 m/s, p = 0.028; -0.14 m, p = 0.001). Preoperative hip and knee kinematics differed significantly from controls. After THA, they improved significantly and did not differ from controls. Dynamic hip flexion-extension ROM correlated positively with all HOOS subscores (r > 0.417; p ≤ 0.001). The change in HOOS symptoms in patients was explained by the combination of baseline HOOS symptoms and change in dynamic hip ROM (r²  = 0.748) suggesting that the additional information gained with IMU gait analysis helps to complement and objectify patient-reported outcome measures pre- and postoperatively and monitor treatment-related improvements.

Do patients with well-functioning total hip arthroplasty achieve typical sagittal plane hip kinematics? A proof of concept study

BACKGROUND

Total hip arthroplasty (THA) patients have been shown to not achieve normal sagittal plane hip kinematics. However, previous studies have only conducted group level analysis and as such lack the sensitivity to highlight whether individual patients do achieve normal hip kinematics. As such this study looked to determine whether some patients with well-functioning THA achieve typical sagittal plane hip kinematics.

METHODS

Sagittal plane hip kinematics were collected on 11 well-functioning THA patients (Oxford Hip Score = 46 ± 3) and 10 asymptomatic controls using a 3-dimensional motion analysis system during self-paced walking. High-functioning THA patients were identified as those who displayed sagittal plane hip kinematics that were within the variance of the control group on average, and low-functioning patients as those who did not.

RESULTS

5 THA patients were identified as high-functioning, displaying hip kinematics within the variance of the control group. High-functioning THA patients displayed peak hip flexion and extension values more closely aligned to asymptomatic control group than low-functioning patients. However, hip range of motion was comparable between high- and low-functioning total hip arthroplasty patients and reduced compared to controls.

CONCLUSION

The presence of high-functioning THA patients who display comparable sagittal plane hip kinematics to controls suggests these patients do achieve normative function and challenges the conclusions of previous group level analysis. Understanding why some patients achieve better function post-operatively will aid pre- and post-operative practices to maximise functional recovery.

Using Gait Analysis to Evaluate Hip Replacement Outcomes—Its Current Use, and Proposed Future Importance: A Narrative Review

Total hip replacement (THR) is one of the most common elective orthopaedic operations. However, evidence suggests that despite postoperative pain improvements, aspects of longer-term physical performance, such as walking ability, do not reach the levels expected when compared to the general population. Walking is best assessed by using gait analysis. This review aims to explain the concept of gait analysis, its use to evaluate THR outcomes, and its proposed future importance when evaluating new technologies proposed to improve functional recovery in individuals undergoing THR surgery. Furthermore, this review discusses the advantages and challenges of gait analysis in THR patients and provides recommendations for future work.

Two-Stage Total Hip Arthroplasty for Primary Advanced Septic Arthritis of the Hip in Adults

Background

Comparing the outcomes of debridement and total hip arthroplasty (THA) with antibiotic-loaded spacer implantation and subsequent THA for the treatment of patients affected by primary advanced septic arthritis (SA) of the hip in adults.

Methods

All of the 20 patients (20 hips) underwent two-stage surgery. Nine patients were submitted to surgical debridement first and then THA (group 1), while 11 patients were treated with antibiotic-loaded spacer and subsequent THA (group 2). Patients were evaluated based on the recurrence of infection, Harris hip score, visual analogue scale (VAS) pain score, and leg length discrepancy.

Results

No cases of infection, deep vein thrombosis, death, and loosening of the hip prosthesis were observed during follow-up. The mean follow-up time was 29.09 ± 10.80 months in group 1 and 28.22 ± 14.80 months in group 2. Before the THA surgery, the mean leg length discrepancy was 2.80 ± 2.03 cm in group 1 and 0.50 ± 0.23 cm in group 2 (P < 0.05). In the latest follow-up, the Harris hip scores of patients were 90.33 ± 4.85 in group 1 and 94.36 ± 2.34 in group 2 (P < 0.05), respectively. There was no statistically significant difference in the VAS pain score of the hip between the two groups (P > 0.05).

Conclusions

Debridement and antibiotic-loaded spacer and subsequent THA were effective in eradicating the infection for advanced SA. However, antibiotic-loaded spacer and subsequent THA was superior for effectively maintaining the length of the lower limb and function of the hip.

Improvement of locomotive syndrome after total hip arthroplasty: A two-year longitudinal cohort study

OBJECTIVES

Patients requiring total hip arthroplasty (THA) may possibly have locomotive syndrome (LS). Therefore, we investigated changes of LS in patients undergoing THA and clarified key factors that affected LS stage.

METHODS

A prospective cohort study was conducted with 88 patients undergoing THA (74 females, 14 males, mean age: 67.6 years). Data collected using LS stage, stand-up test, two-step test, and 25-question Geriatric Locomotive Function Scale results were evaluated before THA, and 6 months, 1 year, and 2 years after THA. Key factors were determined using multivariate analysis and receiver operating characteristic (ROC) curve analysis.

RESULTS

Before THA, all patients had fallen LS (stage1: 3.4% and stage2: 96.6%). Overall, 56.8% patients improved their LS stage, and 17.0% of patients overcame LS at 2 years after THA. The key factors that affected LS stage were preoperative two-step test and age. ROC analyses showed a preoperative two-step test score of 0.988 and an age of 67.5 years as a cut-off value for the change of LS stage.

CONCLUSIONS

Patients experiencing LS due to hip disorders have the potential to recover after THA. Additional postoperative training may be beneficial for patients with low preoperative two-step test scores to improve their LS stage.

Kinematic Gait Analysis After Primary Total Hip Replacement: A Systematic Review: Gait After Total Hip Replacement: A Systematic Review

Total hip replacement (THR) is a surgical procedure indicated for patients affected by severe hip osteoarthritis. Although this technique has proved to be effective in relieving pain and restoring function, gait limitations may persist following this procedure. The objective of this systematic review was to evaluate gait kinematics after THR and compare the results with those of the pre-operative state and with healthy control individuals. PubMed/MEDLINE, Embase, Web of Science, CENTRAL and Scopus databases were searched until December 2019. Methodological quality and internal validity score of each study were assessed using the PEDro and the Newcastle-Ottawa scales. In all, ten studies met our inclusion criteria. Following THR, statistically significant improvements were seen in dynamic hip and knee range of motion of both the affected and the contralateral limb, single-limb support time symmetry, step length, stride length, walking speed and gait pattern. However, deficits were observed in all the previous parameters, as well as in hip adduction angle in comparison with healthy subjects. In conclusion, gait patterns improve after THR in comparison with the pre-operative state, although there are deficits relative to healthy individuals.

Incorporating Specific Functional Strength Integration Techniques to Improve Functional Performance for Veterans After Total Hip Arthroplasty: Protocol for a Randomized Clinical Trial

BACKGROUND

Total hip arthroplasty (THA) is a common procedure, yet persistent deficits in functional performance exist after surgery. These deficits may be related to movement compensations observed after THA, which negatively affect quality of life and may increase morbidity and health care utilization, including in the veteran population. However, the best rehabilitative approach to remediating movement compensations and physical function deficits has not been determined.

OBJECTIVE

The objective is to determine if a functional strength integration intervention (FSI), as part of a post-THA rehabilitation program, improves movement compensation, physical function, muscle strength, and self-reported outcome measures more than a control group (CON) undergoing a standard of care exercise program.

DESIGN

This is a 2-arm randomized, controlled clinical trial.

SETTING

The Veteran Affairs outpatient physical therapy clinics and academic research laboratory will be the settings.

PARTICIPANTS

One hundred veterans undergoing THA for hip osteoarthritis will be included in the study.

INTERVENTIONS

Participants will be randomized to either the FSI or CON group and participate in visits of physical therapy over 8 weeks. The FSI protocol will include targeted exercise to improve muscular control and stability around the hip and trunk to minimize movement compensation during daily activity combined with progressive resistance exercise. The CON protocol will include patient education, flexibility activity, and low load resistance exercise.

MEASUREMENTS

Functional performance, muscle strength and endurance, and self-reported outcomes will be measured at baseline (prior to surgery), midway through intervention (6 weeks after surgery), at the end of intervention (10 weeks after surgery), and 26 weeks after THA.

LIMITATIONS

The inability to blind treating therapists to study arm allocation is a limitation.

CONCLUSIONS

The proposed study aims to determine if targeted FSI can affect movement compensation to improve functional outcomes after THA more than traditional rehabilitation paradigms.

Hip hemiarthroplasty for senile femoral neck fractures: Minimally invasive SuperPath approach versus traditional posterior approach

BACKGROUND

The supercapsular percutaneously-assisted total hip (SuperPATH®) approach was created by combining the percutaneous preparation of the acetabulum using the percutaneously-assisted total hip (PATH), femoral reaming, and broaching of superior capsulotomy (SuperCap) approach. This technique reported a low complication rate, excellent gait kinematics, low transfusion rate, a shorter length of hospital stay, and a high proportion of discharge from the hospital. As minimally invasive SuperPath approach is designed for both trauma and end-stage degenerative joint disease, we investigated if this technique and standard surgical tools can replace artificial femoral head in elderly patients with femoral neck fracture. We also tested if it has advantages over the traditional posterior approach.

METHODS

A prospective study was performed in 100 cases of eligible femoral neck fractures from May 01, 2015 to October 31, 2016. They were randomly divided into SuperPath and traditional group. The outcomes were evaluated using preoperative index, intraoperative data, and postoperative function data.

RESULTS

No significant difference was detected in the operation time between the two groups. Compared with the traditional group, SuperPath group had smaller incision length, less intraoperative bleeding, lower transfusion rate, and a shorter starting time of weight-bearing activity. Harris Hip Score, Barthel Index, and VAS for pain-level scores in the SuperPath group at 1-week follow-up intervals were significantly lower than the conventional group, but not significantly different at 3-month and 2-year follow-up post-operation.

CONCLUSIONS

SuperPath approach for artificial femoral head replacement can reduce surgical injury due to smaller size of incision and accelerate weight-bearing activities post-operation to treat senile femoral neck fractures compared with traditional posterior approach surgeries.

Static and dynamic abductor function are both associated with physical function 1 to 5 years after total hip arthroplasty

BACKGROUND

A subset of total hip arthroplasty patients experience functional impairments past the first postoperative year. Poor hip abductor function is common before and in the early postoperative period. It is not known if abductor impairment is associated with long-term functional impairment. This study evaluated the relationships between static and dynamic abductor function and performance-based and self-reported function >1 year post-total hip arthroplasty.

METHODS

Eighteen adults 1-5 years post-total hip arthroplasty participated. Static and dynamic abductor function were assessed through dynamometry and gait analysis, respectively. Subjects completed four physical performance tests and two self-report instruments.

FINDINGS

Higher peak isometric abductor strength was associated with better performance-based function (P ≤ 0.001-0.030) and with self-reported function (P ≤ 0.001-0.012). Higher peak external adduction moment was associated with better results on 3 of 4 performance tests (P = 0.007-0.026). Together, static and dynamic abductor function predicted 35-77% of the variation in physical function. Abductor strength best predicted walking test results and self-reported function, while dynamic abductor function best predicted tests involving sit-to-stand INTERPRETATION: Static and dynamic abductor function were associated with physical function 1-5 years after total hip arthroplasty. These results support further investigation of interventions targeting abductor function for persons experiencing persistent impairments.

Muscle Damage in Different Approaches in Total Hip Arthroplasty According to Serum Markers

Background:

Total Hip Arthroplasty (THA) is the final treatment of end-stage hip osteoarthritis. Nowadays, THA has become very common, cost- effective and one of the most successful orthopaedic procedures. Recently, surgeons have shifted their interest to approaches according to Minimally Invasive Surgery (MIS). These approaches are either modifications of conventional approaches or they are designed from the beginning as MIS approaches. Muscle damage and soft tissue damage are issues that concern researchers who perform studies on THA.

Objective:

The aim of this study is to review the literature concerning studies by comparing different approaches using serum and inflammatory markers for muscle and soft tissue damage.

Methods:

We searched the PubMed database in the English language systematically for clinical studies or reviews, comparing muscle damage according to serum markers between two or more approaches in primary total arthroplasty.

Results:

In total, twenty-one studies were included in this review. Although the results are controversial, it seems that MIS approaches in most of the studies were related to lower levels of inflammation markers contrasting with conventional approaches. Nevertheless, this difference in muscle damage is not correlated with a difference in functional scores or other perioperative data and clinical outcomes in all studies.

Conclusion:

The existing literature does not lead to a safe consensus about the superiority of any approach. Therefore, there is still a need for further research with well-designed studies.

Biomechanical changes and recovery of gait function after total hip arthroplasty for osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

To determine the change in walking gait biomechanics after total hip arthroplasty (THA) for osteoarthritis (OA) compared to the pre-operative gait status, and to compare the recovery of gait following THA with healthy individuals.

METHODS

Systematic review with meta-analysis of studies investigating changes in gait biomechanics after THA compared to (1) preoperative levels and (2) healthy individuals. Data were pooled at commonly reported time points and standardised mean differences (SMDs) were calculated in meta-analyses for spatiotemporal, kinematic and kinetic parameters.

RESULTS

Seventy-four studies with a total of 2,477 patients were included. At 6 weeks postoperative, increases were evident for walking speed (SMD: 0.32, 95% confidence intervals (CI) 0.14, 0.50), stride length (SMD: 0.40, 95% CI 0.19, 0.61), step length (SMD: 0.41, 95% CI 0.23, 0.59), and transverse plane hip range of motion (ROM) (SMD: 0.36, 95% CI 0.05, 0.67) compared to pre-operative gait. Sagittal, coronal and transverse hip ROM was significantly increased at 3 months (SMDs: 0.50 to 1.07). At 12 months postoperative, patients demonstrated deficits compared with healthy individuals for walking speed (SMD: -0.59, 95% CI -1.08 to -0.11), stride length (SMD: -1.27, 95% CI -1.63, -0.91), single limb support time (SMD: -0.82, 95% CI -1.23, -0.41) and sagittal plane hip ROM (SMD: -1.16, 95% CI -1.83, -0.49). Risk of bias scores ranged from seven to 24 out of 26.

CONCLUSIONS

Following THA for OA, early improvements were demonstrated for spatiotemporal and kinematic gait patterns compared to the pre-operative levels. Deficits were still observed in THA patients compared to healthy individuals at 12 months.

Hip abductor strength and fatigue are associated with activity levels more than 1 year after total hip replacement

Despite improvements in pain and function, people who undergo total hip arthroplasty (THR) may not always return to desired levels of physical activity (PA). The factors associated with low activity levels are not fully understood. Abductor weakness and fatigue have both been proposed as factors that limit activity in older adults or people with hip osteoarthritis, but have not been investigated after THR. We hypothesized that abductor weakness and fatigue are associated with lower activity levels in people who have undergone a THR and that fatigue mediates the association between abductor strength and activity. We evaluated 16 subjects (24 ± 10 months post-THR; age 56.8 ± 8.4 yrs; BMI 31 ± 7 kg/m² ). Fatigue was assessed using the PROMIS fatigue short-form 7a. Peak isometric hip abductor torque was assessed using a dynamometer with subjects in a sidelying position. We assessed activity level using the UCLA activity score. We used Pearson correlations to explore the associations among the variables. Next we used a three-step linear regression procedure to test whether or not fatigue acted as a mediator between abductor torque and UCLA activity scores. Higher abductor torque was associated with less fatigue (R²  = 0.275; p = 0.037) and with higher UCLA scores (R²  = 0.488, p = 0.003). Higher fatigue was associated with lower UCLA scores (R²  = 0. 307, p = 0.017), however there was no evidence of mediation. This suggests that addressing both abductor strength and fatigue may increase physical activity. Statement of Clinical Significance: Fatigue and abductor weakness should be evaluated in sedentary THR patients presenting for long-term follow-up. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1519-1525, 2018.

Longitudinal joint loading in patients before and up to one year after unilateral total hip arthroplasty

Abnormal kinematics and kinetics have been reported in hip osteoarthritis (OA) patients before and after total hip arthroplasty (THA). These changes can affect the loading of the ipsilateral hip, as well as the contralateral hip and knee joint. As it is not clear how hip and knee loading evolves in THA patients during the first year after surgery, the goal of this study is to define how joint loading changes in patients before and at three evaluation times after THA surgery. Musculoskeletal modelling in combination with gait analysis data was used to calculate hip and knee contact forces in 14 patients before and 3-, 6- and 12-months after unilateral THA, as well as in 18 healthy controls. Results showed that bilateral hip and knee loading were decreased compared to controls, both before and after THA surgery. Loading symmetry was altered compared to controls at 3-months post-surgery for the hip and at all evaluation times, except for 6-months post-surgery, for the knee, with ipsilateral joint loading decreased compared to the contralateral side. To conclude, 12-months after THA joint loading was not normalized, with both hip and knee loading in patients decreased compared to controls. Therefore, no overloading of the ipsi- or contralateral hip and knee joint was found before and up to one year after unilateral THA.

Hip movement pathomechanics of patients with hip osteoarthritis aim at reducing hip joint loading on the osteoarthritic side

This study aims at defining gait pathomechanics in patients with hip osteoarthritis (OA) and their effect on hip joint loading by combining analyses of hip kinematics, kinetics and contact forces during gait. Twenty patients with hip OA and 17 healthy volunteers matched for age and BMI performed three-dimensional gait analysis. Hip OA level was evaluated based on plane radiographs using the Tönnis classification. Hip joint kinematics, kinetics as well as hip contact forces were calculated. Waveforms were time normalized and compared between groups using statistical parametric mapping analysis. Patients walked with reduced hip adduction angle and reduced hip abduction and external rotation moments. The work generated by the hip abductors during the stance phase of gait was largely decreased. These changes resulted in a decrease and a more vertical and anterior orientation of the hip contact forces compared to healthy controls. This study documents alterations in hip kinematics and kinetics resulting in decreased hip loading in patients with hip OA. The results suggested that patients altered their gait to increase medio-lateral stability, thereby decreasing demand on the hip abductors. These findings support discharge of abductor muscles that may bear clinical relevance of tailored rehabilitation targeting hip abductor muscles strengthening and gait retraining.

Sex-specific hip osteoarthritis-associated gait abnormalities: Alterations in dynamic hip abductor function differ in men and women

BACKGROUND

Hip osteoarthritis results in abnormal gait mechanics, but it is not known whether abnormalities are the same in men and women. The hypothesis tested was that gait abnormalities are different in men and women with hip osteoarthritis vs. sex-specific asymptomatic groups.

METHODS

150 subjects with mild through severe radiographic hip osteoarthritis and 159 asymptomatic subjects were identified from an Institutional Review Board-approved motion analysis data repository. Sagittal plane hip range of motion and peak external moments about the hip, in all three planes, averaged from normal speed walking trials, were compared for men and women, with and without hip osteoarthritis using analysis of variance.

FINDINGS

There were significant sex by group interactions for the external peak hip adduction and external rotation moments (P=0.009-0.045). Although asymptomatic women had peak adduction and external rotation moments that were respectively 12% higher and 23% lower than asymptomatic men (P=0.026-0.037), these variables did not differ between men and women with hip osteoarthritis (P≥0.684). The osteoarthritis vs. asymptomatic group difference in the peak hip adduction moment was 45% larger in women than in men. The osteoarthritis vs. asymptomatic group difference in the peak hip external rotation moment was 55% larger for men than for women (P<0.001). Sex did not influence the association between radiographic severity and gait variables.

INTERPRETATION

Normal sex differences in gait were not seen in hip osteoarthritis. Sex-specific adaptations may reflect different aspects of hip abductor function. Men and women with hip osteoarthritis may require different interventions to improve function.

A 10-Year Follow-Up of Two-Incision and Modified Watson-Jones Total Hip Arthroplasty in Patients with Osteonecrosis of the Femoral Head

Long-term data and information indicating whether minimally invasive surgery (MIS) approaches are safe and effective with total hip arthroplasty (THA) are lacking. Between 2004 and 2006, 75 patients with alcohol-related osteonecrosis of the femoral head (ONFH) who underwent 75 THAs with the two-incision approach were studied. The medical records, radiographic parameters, and functional outcomes were collected prospectively. All data were compared with those for matched patients who underwent a modified Watson-Jones (WJ) approach. THA using the two-incision approach was associated with longer operation time, more blood loss, more lateral femoral cutaneous nerve injury, and more periprosthetic femoral fractures (p < 0.05 for all four) than the modified WJ approach. The Harris Hip Score (HHS) and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) increased significantly from the period preoperatively to 6 weeks postoperatively and thereafter up to the last follow-up in both groups. However, there were no significant differences in terms of radiographic parameters and functional outcomes between the two groups throughout the study period. Both the two-incision and the modified WJ approach provided satisfactory results and survival rates at a mean follow-up of 10.8 years. A prospective, randomized, large-scale cohort study is still warranted for evidence-based recommendations.

Gait kinetics of total hip replacement patients-A large scale, long-term follow-up study

BACKGROUND

It is not known if lower limb gait kinetics of total hip replacement (THR) patients reach normal levels at long term follow-up post-operatively.

METHODS

Three-dimensional gait analysis was performed on 134 THR patients with identical implants 10-years post-operatively. Lower limb moments and powers were compared between different age strata (54-64 years, 65-69 years, 70-74 years, 75-79 years and over 80 years) and a normal elderly control group.

RESULTS

Hip extensor moment and hip power generation were significantly reduced in all age groups compared to normal. External hip rotation moment was significantly reduced in all age groups, apart from the youngest group, compared to normal. However, in contrast to previous short term follow-up studies there was no significant difference in hip abduction moment between any of the age groups and the normal group.

CONCLUSION

This large cohort study shows that, at long term follow-up following THR, some hip joint kinetics (hip extensor and external rotation moments and hip power generation) do not reach normal levels, but that peak abduction moment is preserved. THR patients recovery could potentially benefit from intensive rehabilitation focusing on hip extension and external rotation in the post-operative, and perhaps preoperative, period.

Preoperative gait mechanics predict clinical response to total hip arthroplasty

Some patients do not have an adequate clinical response to total hip arthroplasty (THA) for reasons that are not fully understood. Identifying modifiable factors that are associated with nonresponse could lead to new ways to identify and treat potential nonresponders. This study investigated whether any preoperative gait characteristics were associated with THA clinical response, and whether or not there were corresponding postoperative gait differences in THA nonresponders compared to responders. A secondary analysis was conducted of 124 subjects (age 61 ± 10 years; 64 female/60 male), evaluated before and 1 year after primary unilateral THA, using quantitative gait analysis and Harris Hip Scores (HHS). Responders and nonresponders were identified using the OMERACT-OARSI responder criteria, modified for use with the HHS. Pre- and postoperative dynamic sagittal plane range of motion (ROM) and 3D peak external moments were compared, for responders and nonresponders, using t-tests and logistic regression. 11.3% of subjects were nonresponders. Before surgery, the ROM was 26% higher for nonresponders than responders, but the peak external rotation moment was 30% lower (p = 0.003-0.043). Preoperative gait and HHS predicted response with a sensitivity of 71.4% and a specificity of 99.1%. There were persistent postoperative deficits in the peak external rotation moment in nonresponders compared to responders (p = 0.028). This study showed that gait analysis, where available, can augment clinical scores in predicting THA response. Moreover, it suggests that further analysis of the subtle role of transverse plane hip mechanics could lead to interventions to promote better THA response. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:366-376, 2017.

Factors associated with restricted hip extension during gait in women after total hip arthroplasty

PURPOSE

A decreased peak hip extension angle in the late stance phase is a major gait abnormality in patients with THA. The purpose of this study was to determine the relationship between peak hip extension angle during gait and functional impairments such as muscle weakness and the limitation in joint range of motion and to identify the clinical factors influencing peak hip extension angle during gait.

METHODS

67 female volunteers with THA were examined. Biomechanical gait analysis was performed to measure peak hip extension angle during gait. Maximal isometric strength of the hip and knee, passive hip extension range of motion, leg length discrepancy, and hip pain were assessed.

RESULTS

Peak hip extension angle during gait significantly correlated with passive hip extension range of motion (r = 0.259), hip pain (r = -0.264), isometric strengths of the hip musculature (r = 0.278-0.491), and knee extensor (r = 0.386). Stepwise multiple regression analysis revealed that hip abductor torque (β = 0.355, P = 0.001), hip pain (β = -0.353, P = 0.001), and passive hip extension range of motion (β = 0.258, P = 0.011) were significant contributors to peak hip extension angle during gait (R2 = 0.408).

CONCLUSIONS

Our findings suggest that THA rehabilitation aimed at improving gait ability should focus on strengthening the hip abductors, controlling hip pain and increasing range of motion of hip extension.

Rehabilitation of gait in patients after total hip arthroplasty: Comparison of the minimal invasive Yale 2-incision technique and the conventional lateral approach

The minimal invasive anterolateral Yale 2-incision approach for total hip arthroplasty aims minimizing damage to the muscles for faster recovery of function. Therefore the hypothesis was investigated, that during the rehabilitation process the Yale approach shows a faster return to natural gait than a conventional lateral approach. Nineteen patients had the Yale, 16 the conventional Bauer approach. Instrumented gait analysis was performed 3 days, 3 and 12 month post operatively. Velocity, cadence, step length, weight bearing, thorax lean, Trendelenburg limp, hip abduction moments, and hip muscle activation times were evaluated. Three days post-surgery a significantly greater loading of the treated limb and increased hip abduction moment were observed in the Yale group. In addition, the Yale group showed its greatest improvement in walking speed and step length between at 3 days and 3 months, whereas the conventional group showed an additional significant gain between 3 and 12 month to reach a similar walking speed as the Yale group. For all hip muscles investigated, only muscle tensor fasciae latae in the conventional group showed a significant increase in activation time between 3 days and 3 months. This study showed significantly faster return to natural gait in the Yale compared to the conventional approach, which could be biomechanically related to less impairment of abductor muscles in the Yale approach.

Effects of neuromuscular reeducation on hip mechanics and functional performance in patients after total hip arthroplasty: A case series

BACKGROUND

Following total hip arthroplasty, patients demonstrate compensatory movement strategies during activities of daily living such as walking and stair climbing. Movement compensations are important markers of functional decline in older adults and are related to poor functional capacity. Despite increased utilization of hip arthroplasty, persistent movement compensation, and functional performance deficits, no consensus on postoperative rehabilitation exists. Neuromuscular reeducation techniques offer a strategy to improve movement quality by emphasizing hip abductor performance and pelvic stability. This case series illustrates changes in movement strategy around the hip in response to targeted neuromuscular reeducation techniques after hip arthroplasty.

METHODS

Five participants received an 8-week exercise program following total hip arthroplasty, emphasizing targeted neuromuscular reeducation techniques hallmarked by specific, weight-bearing exercise to improve hip abductor performance and pelvic stability. Five additional participants were supervised and followed for comparison.

FINDINGS

Participants in the neuromuscular reeducation program improved their internal hip abductor moments and vertical ground reaction forces during walking and stair climbing. They also improved their functional performance and hip abductor strength outcomes.

INTERPRETATION

Targeted neuromuscular reeducation techniques after total hip arthroplasty provided a positive effect on biomechanical outcomes, functional performance, and muscle strength. Through focused use of the hip abductor muscles, increased internal hip abductor moments were observed. This intervention potentially promotes pelvic stability, and may contribute to improved performance on tasks such as stair climbing, fast walking, and balance. The results suggest that neuromuscular reeducation offers a unique effect on movement strategy and function for patients following total hip arthroplasty.

Does surgical approach or prosthesis type affect hip joint loading one year after surgery?

Several approaches may be used for hip replacement surgery either in combination with conventional total hip arthroplasty (THA) or resurfacing hip arthroplasty (RHA). This study investigates the differences in hip loading during gait one year or more after surgery in three cohorts presenting different surgical procedures, more specific RHA placed using the direct lateral (RHA-DLA, n=8) and posterolateral (RHA-PLA, n=14) approach as well as THA placed using the direct anterior (THA-DAA, n=12) approach. For the DAA and control subjects, hip loading was also evaluated during stair ascent and descent to evaluate whether these motions can better discriminate between patients and controls compared to gait. Musculoskeletal modelling in OpenSim was used to calculate in vivo joint loading. Results showed that for all operated patients, regardless the surgical procedure, hip loading was decreased compared to control subjects, while no differences were found between patient groups. This indicates that THA via DAA results in similar hip loading as a RHA via DLA or PLA. Stair climbing did not result in more distinct differences in hip contact force magnitude between patients and controls, although differences in orientation were more distinct. However, patients after hip surgery did adjust their motion pattern to decrease the magnitude of loading on the hip joint compared to control subjects.

Identifying clinically meaningful benchmarks for gait improvement after total hip arthroplasty

There are no established benchmarks for gait mechanics after total hip arthroplasty (THA). This study sought to identify minimum clinically important postoperative (MCIP) or minimum clinically important improvement (MCII) values for self-selected walking speed, sagittal plane dynamic hip range of motion (HROM) (peak flexion-peak extension) and peak hip adduction moments measured during quantitative gait analysis. Preoperative and 1-year postoperative data collected during quantitative gait analysis, along with Harris Hip Scores (HHS), for 145 subjects were collected from a motion analysis data repository. The MCIP (or MCII) was defined as the 75th percentile mark on a plot of the cumulative percent of subjects with HHS ≥ 80 versus the postoperative value (or change) in the respective variable. 95% confidence intervals (CI) were calculated. Logistic regression was used to test the association of age, sex, BMI, and preoperative HHS with benchmarks. The MCIP of speed was 1.34 m/s (95%CI 1.30, 1.37); MCII was 0.32 (0.30, 0.35) m/s. The HROM MCIP was 30.0° (29.4°, 30.7°); MCII was 13.3° (12.1°, 14.8°). The adduction moment MCIP was 4.2% Body Weight × Height (4.0, 4.4); MCII was 0.87 (0.57, 1.17) % Body Weight × Height. Women were more likely to achieve MCII for HROM and MCIP for adduction moment (ORs 2.4-11.6, p ≤ 0.031). Lower BMI predicted HROM and adduction moment MCIPs (ORs 0.85-0.88, p ≤ 0.015). Lower preoperative HHS predicted speed, HROM and adduction moment MCIIs (ORs 0.95-0.97, p ≤ 0.012). With further validation, clinically-relevant gait benchmarks can enhance efforts to improve THA outcomes.

Total hip replacement and surface replacement for the treatment of pain and disability resulting from end-stage arthritis of the hip (review of technology appraisal guidance 2 and 44): systematic review and economic evaluation

BACKGROUND

Total hip replacement (THR) involves the replacement of a damaged hip joint with an artificial hip prosthesis. Resurfacing arthroplasty (RS) involves replacement of the joint surface of the femoral head with a metal surface covering.

OBJECTIVES

To undertake clinical effectiveness and cost-effectiveness analysis of different types of THR and RS for the treatment of pain and disability in people with end-stage arthritis of the hip, in particular to compare the clinical effectiveness and cost-effectiveness of (1) different types of primary THR and RS for people in whom both procedures are suitable and (2) different types of primary THR for people who are not suitable for hip RS.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, The Cochrane Library, Current Controlled Trials and UK Clinical Research Network (UKCRN) Portfolio Database were searched in December 2012, with searches limited to publications from 2008 and sample sizes of ≥ 100 participants. Reference lists and websites of manufacturers and professional organisations were also screened.

REVIEW METHODS

Systematic reviews of the literature were undertaken to appraise the clinical effectiveness and cost-effectiveness of different types of THR and RS for people with end-stage arthritis of the hip. Included randomised controlled trials (RCTs) and systematic reviews were data extracted and risk of bias and methodological quality were independently assessed by two reviewers using the Cochrane Collaboration risk of bias tool and the Assessment of Multiple Systematic Reviews (AMSTAR) tool. A Markov multistate model was developed for the economic evaluation of the technologies. Sensitivity analyses stratified by sex and controlled for age were carried out to assess the robustness of the results.

RESULTS

A total of 2469 records were screened of which 37 were included, representing 16 RCTs and eight systematic reviews. The mean post-THR Harris Hip Score measured at different follow-up times (from 6 months to 10 years) did not differ between THR groups, including between cross-linked polyethylene and traditional polyethylene cup liners (pooled mean difference 2.29, 95% confidence interval -0.88 to 5.45). Five systematic reviews reported evidence on different types of THR (cemented vs. cementless cup fixation and implant articulation materials) but these reviews were inconclusive. Eleven cost-effectiveness studies were included; four provided relevant cost and utility data for the model. Thirty registry studies were included, with no studies reporting better implant survival for RS than for all types of THR. For all analyses, mean costs for RS were higher than those for THR and mean quality-adjusted life-years (QALYs) were lower. The incremental cost-effectiveness ratio for RS was dominated by THR, that is, THR was cheaper and more effective than RS (for a lifetime horizon in the base-case analysis, the incremental cost of RS was £11,284 and the incremental QALYs were -0.0879). For all age and sex groups RS remained clearly dominated by THR. Cost-effectiveness acceptability curves showed that, for all patients, THR was almost 100% cost-effective at any willingness-to-pay level. There were age and sex differences in the populations with different types of THR and variations in revision rates (from 1.6% to 3.5% at 9 years). For the base-case analysis, for all age and sex groups and a lifetime horizon, mean costs for category E (cemented components with a polyethylene-on-ceramic articulation) were slightly lower and mean QALYs for category E were slightly higher than those for all other THR categories in both deterministic and probabilistic analyses. Hence, category E dominated the other four categories. Sensitivity analysis using an age- and sex-adjusted log-normal model demonstrated that, over a lifetime horizon and at a willingness-to-pay threshold of £20,000 per QALY, categories A and E were equally likely (50%) to be cost-effective.

LIMITATIONS

A large proportion of the included studies were inconclusive because of poor reporting, missing data, inconsistent results and/or great uncertainty in the treatment effect estimates. This warrants cautious interpretation of the findings. The evidence on complications was scarce, which may be because of the absence or rarity of these events or because of under-reporting. The poor reporting meant that it was not possible to explore contextual factors that might have influenced study results and also reduced the applicability of the findings to routine clinical practice in the UK. The scope of the review was limited to evidence published in English in 2008 or later, which could be interpreted as a weakness; however, systematic reviews would provide summary evidence for studies published before 2008.

CONCLUSIONS

Compared with THR, revision rates for RS were higher, mean costs for RS were higher and mean QALYs gained were lower; RS was dominated by THR. Similar results were obtained in the deterministic and probabilistic analyses and for all age and sex groups THR was almost 100% cost-effective at any willingness-to-pay level. Revision rates for all types of THR were low. Category A THR (cemented components with a polyethylene-on-metal articulation) was more cost-effective for older age groups. However, across all age-sex groups combined, the mean cost for category E THR (cemented components with a polyethylene-on-ceramic articulation) was slightly lower and the mean QALYs gained were slightly higher. Category E therefore dominated the other four categories. Certain types of THR appeared to confer some benefit, including larger femoral head sizes, use of a cemented cup, use of a cross-linked polyethylene cup liner and a ceramic-on-ceramic as opposed to a metal-on-polyethylene articulation. Further RCTs with long-term follow-up are needed.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013003924.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Preoperative factors associated with postoperative gait kinematics and kinetics after total hip arthroplasty

OBJECTIVE

To determine how patient factors: age, sex, body mass index (BMI), clinical scores and physical exam findings, are associated with gait recovery after total hip arthroplasty (THA).

METHOD

145 subjects, who were evaluated with standard gait analysis, the Harris Hip Score (HHS), and a physical exam including passive range of motion (ROM), hip abductor strength assessment, before and after primary unilateral THA, were identified from an IRB-approved repository. Sagittal plane dynamic ROM and 3D peak external moments were averaged from operated-side normal-speed trials at each visit. We used linear regression analysis to evaluate the association among preoperative clinical factors and postoperative gait, with and without controlling for the influence of preoperative gait variables.

RESULTS

Sagittal and transverse plane moments, and the peak abduction moment seen in early stance, significantly improved after THA (p < 0.001, effect size d = 0.22-1.04). The peak adduction moment did not change significantly (p = 0.646), although the change ranged from -2.7 to + 4.0 %Body weight × height (-80% to +315%). Preoperative gait, clinical factors and patient characteristics predicted up to 33% of the variability in postoperative gait. Notably, greater preoperative abductor strength was associated with higher postoperative adduction and external rotation moments (R = 0.197-0.266, p < 0.05) after adjusting for age, sex, BMI and preoperative gait.

CONCLUSION

Preoperative clinical factors predicted several specific aspects of objectively-characterized postoperative gait function. Physical exam findings can augment the predictive ability of clinical outcome measures, and potentially help guide rehabilitation plans.

Percutaneously assisted total hip (PATH) and Supercapsular percutaneously assisted total hip (SuperPATH) arthroplasty: learning curves and early outcomes

BACKGROUND

A new family of micro-posterior approaches, percutaneously assisted total hip (PATH), SuperCapsular (SuperCap) and Supercapsular percutaneously assisted total hip (SuperPATH) allow preservation of the short external rotators. This study assesses early outcomes and learning curves of the PATH and SuperPATH approaches.

METHODS

Early outcomes of the first consecutive 49 PATH and 50 SuperPATH cases performed by a non-developer surgeon were evaluated. Analysis of variance (ANOVA) was used to compare age, body mass index (BMI), and pre-operative hemoglobin. Gender was compared using a Chi-square test. Clinical outcomes were compared using a nonparametric Wilcoxon test or a Chi-square test. Learning curves were assessed using operative time as a surrogate. Acetabular cup abduction and anteversion were compared using the first post-operative radiograph and a modified protractor.

RESULTS

Both cohorts were similar with respect to diagnosis, gender, and BMI. Mean operative time in minutes was recorded for the PATH (114.5±17.5) and SuperPATH (101.7±18.3) cohorts (P value =0.0002). PATH operative time reached a plateau by case 40, but SuperPATH operative time continued to decrease by case 50. Transfusion rates were low in the PATH (4%) and SuperPATH (6%) cohorts. Mean length of stay (LOS) in days for the SuperPATH and PATH cohorts were 2.2 and 3.0, respectively (P value <0.0001). Complication rates were low in the SuperPATH (4.0%) and PATH (4.1%) cohorts. Acetabular cups in the SuperPATH cohort (anteversion: 23.5°±8.2°, abduction: 39.0°±8.4°) were significantly more anteverted (P value <0.0001) and less abducted (P value <0.05) than in the PATH cohort (anteversion: 13.1°±7.1°; abduction: 42.9°±7.6°).

CONCLUSIONS

Early results demonstrate that the PATH and SuperPATH approaches can be adopted with minimal complications and outcomes consistent with innovator outcomes, even during the learning curve. The SuperPATH technique was associated with shorter operative time that continued to decrease, suggesting that proficiency continues to decrease beyond the first 50 cases. In this author's experience, acetabular cups implanted using the SuperPATH technique were more anteverted than those implanted using the PATH technique. Greater use of the transverse acetabular ligament to guide cup alignment reduced this effect.

Are Harris hip scores and gait mechanics related before and after THA?

BACKGROUND

Discordance between subjective and objective functional measures hinders the development of new ways to improve THA outcomes.

QUESTIONS/PURPOSES

We asked if (1) any kinematic or kinetic gait variables are correlated with preoperative Harris hip scores (HHS), (2) any kinematic or kinetic gait variables are correlated with postoperative HHS, and (3) pre- to postoperative changes in any kinematic or kinetic gait variables are associated with the change in HHS?

METHODS

For this retrospective study, an institutional review board-approved data repository that included all individuals who participated in motion analysis research studies was used to identify subjects evaluated before (n=161) and at least 6 months after primary unilateral THA (n=156). Selected kinematic (sagittal plane dynamic hip ROM and kinetic (peak external moments about the hip in the sagittal, frontal, and transverse planes) gait variables were collected at subjects' self-selected normal walking speeds. We used first-order partial correlations to identify relationships between HHS and gait variables, controlling for the influence of speed.

RESULTS

Preoperative HHS correlated with hip ROM (R|speed=0.260; p<0.001) and the peak extension moment (R|speed=0.164; p=0.038), postoperative HHS correlated with the peak internal rotation moment (R|speed=0.178; p=0.034), and change in HHS correlated with change in hip ROM (R|speed=0.288; p=0.001) and peak external rotation moment (R|speed=0.291; p=0.002). Similar associations were seen when the HHS pain and function were analyzed separately.

CONCLUSIONS

This study identified relationships between a common clinical outcome measure and specific, modifiable gait adaptations that can persist after THA-ROM and transverse plane gait moments. Addressing these aspects of gait dysfunction through focused rehabilitation could be a new strategy for improving clinical outcomes. Prospective studies are needed to evaluate this concept.

LEVEL OF EVIDENCE

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

Gait and gait-related activities of daily living after total hip arthroplasty: a systematic review

BACKGROUND

Differences in the performance of gait and gait-related activities of daily living are known to persist after total hip arthroplasty compared to healthy controls, but the specific underlying deficits (spatiotemporal, kinematics and kinetics) are not completely understood. This review aimed to map the differences between patients and controls, and between the operated and non-operated limbs during various activities of daily living.

METHODS

A computerized search with broad search terms was performed in the MEDLINE database. Primary inclusion criteria were: primary osteoarthritis as indication, comparison with healthy controls or comparison between the operated and the non-operated limbs, and follow-up period at least six months after surgery.

FINDINGS

The literature search yielded 2177 citations, of which 35 articles were included. Compared to controls, reductions were identified in the operated hip in sagittal range of motion, peak extension, sagittal power generation, abduction moment and external rotation moment. During stair ascent, these reductions did not become more apparent, although deficits in hip kinetics in all three planes were found. Walking speed and step length were reduced compared to controls at longer-term follow-up, but not at short-term follow-up.

INTERPRETATION

The hip abduction moment deficit was present both in level walking and in stair ascent in total hip arthroplasty patients compared to controls. Reduced sagittal hip power generation and external rotation moment were also found, of which the clinical relevance remains to be established. Due to a low number of studies, many of the longer-term effects of THA on gait and gait-related ADL are not yet accurately known.

Muscle strength and functional recovery during the first year after THA

BACKGROUND

Patients undergoing total hip arthroplasty (THA) often are satisfied with the decrease in pain and improvement in function they achieve after surgery. Even so, strength and functional performance deficits persist after recovery, but these remain poorly characterized; knowledge about any ongoing strength or functional deficits may allow therapists to design rehabilitation programs to optimize recovery after THA.

QUESTIONS/PURPOSES

The purposes of this study were to (1) evaluate postoperative muscle strength, function, and quality of life during the first year after THA; and (2) compare strength and function in patients 1 year after THA with a cohort of healthy peers.

METHODS

Twenty-six patients undergoing THA were assessed 1, 3, 6, and 12 months postoperatively, and 19 adults with no hip pathology were tested as a control group. Isometric muscle strength (hip flexors, extensors, abductors, knee extensors, and flexors), functional performance (stair climbing, five times sit-to-stand, timed-up-and-go, 6-minute walk, and single-limb stance tests), and self-reported function (Hip Disability and Osteoarthritis Score, SF-36, and UCLA activity score) were compared.

RESULTS

One month after THA, patients had 15% less hip flexor and extensor torque, 26% less abductor torque, 14% less knee extensor and flexor torque, and worse performance on the stair climbing, timed-up-and-go, single-limb stance, and 6-minute walk. Compared with healthy adults, patients 12 months after THA had 17% less knee extensor and 23% less knee flexor torque; however, the functional testing (including stair climbing, five times sit-to-stand, and the 6-minute walk) showed no significant differences with the patient numbers available between individuals undergoing THA and healthy control subjects. SF-36 Physical Component Scores, although significantly improved from preoperative levels, were significantly worse than healthy adults 1 year after THA (p < 0.01).

CONCLUSIONS

Patients experience early postoperative strength losses and decreased functional capacity after THA, yet strength deficits may persist after recovery. This may suggest that rehabilitation may be most effective in the first month after surgery.

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.

Does hip implant positioning affect the peak external adduction moments of the healthy knees of subjects with total hip replacements?

After unilateral total hip replacement (THR) for hip osteoarthritis (OA), knee OA incidence or progression is common. The contralateral knee is at particular risk, and some have speculated that abnormal THR-hip biomechanics contributes to this asymmetry. We investigated the relationships between operated-hip joint geometry or gait variables and the peak external knee adduction moments-an indicator of knee OA risk-in 21 subjects with unilateral THRs. We found that the peak adduction moment was 14% higher on the contralateral versus the ipsilateral knee (p = 0.131). The best predictors of ipsilateral knee adduction moments were superior-inferior joint center position and operated-hip peak adduction moment (adj R(2)  = 0.291, p = 0.017). The sole predictor of the contralateral knee adduction moment was the medial-lateral hip center position (adj R(2)  = 0.266, p = 0.010). A postoperative medial shift of the hip center was significantly correlated with a lower postoperative contralateral/ipsilateral knee adduction moment ratio (R = 0.462, p = 0.035). Based on these relationships, we concluded that implant positioning could influence the biomechanical risk of knee OA progression after THR. Although implant positioning decisions are necessarily driven by other factors, it may be appropriate to assess individual THR candidate's knee OA risk and adjust perioperative management accordingly.

Comparison of gait in patients following a computer-navigated minimally invasive anterior approach and a conventional posterolateral approach for total hip arthroplasty: a randomized controlled trial

Minimally invasive total hip arthroplasty (MIS THA) aims at minimizing damage to muscles and tendons to accelerate postoperative recovery. Computer navigation allows a precise prosthesis alignment without complete visualization of the bony landmarks during MIS THA. A randomized controlled trial (RCT) was conducted to determine the effectiveness of a computer-navigated MIS anterior approach for THA compared to a conventional posterolateral THA technique on the restoration of physical functioning during recovery following surgery. Thirty-five patients underwent computer-navigated MIS THA via the anterior approach, and 40 patients underwent conventional THA using the conventional posterolateral approach. Gait analysis was performed preoperatively, 6 weeks, and 3 and 6 months postoperatively using a body-fixed-sensor based gait analysis system. Walking speed, step length, cadence, and frontal plane angular movements of the pelvis and thorax were assessed. The same data were obtained from 30 healthy subjects. No differences were found in the recovery of spatiotemporal parameters or in angular movements of the pelvis and thorax following the computer-navigated MIS anterior approach or the conventional posterolateral approach. Although gait improved after surgery, small differences in several spatiotemporal parameters and angular movements of the trunk remained at 6 months postoperatively between both patient groups and healthy subjects.

Outcomes of minimally invasive anterolateral THA are not superior to those of minimally invasive direct lateral and posterolateral THA

BACKGROUND

There has been considerable interest in minimally invasive surgical (MIS) THA in recent years. The MIS anterolateral approach, or the MIS Watson-Jones approach, is a novel intermuscular abductor-sparing technique. Early reports from case series suggest the potential for superior function and reduced complications; however, the available information from clinical reports is inadequate to suggest surgeons should change from their accepted standard approach.

QUESTIONS/PURPOSES

We examined the potential superiority of this anterolateral approach, as judged by quality-of-life (QoL) measures, radiographic parameters, and complications, compared to limited-incision MIS direct lateral and MIS posterolateral approaches.

METHODS

We performed a prospective randomized controlled trial involving five surgeons at three centers, recruiting 156 patients undergoing primary THA to receive either the MIS anterolateral or the surgeon's preferred approach (direct lateral or posterolateral). For the 135 patients we report, we collected patient-reported WOMAC, SF-36, Paper Adaptive Test in 5 Domains of Quality of Life in Arthritis Questionnaire [PAT5D], and patient satisfaction scores. We recorded complications and evaluated radiographs for prosthetic component position, subsidence, and fracture. Minimum followup was 24 months (mean, 30 months; range, 24-42 months).

RESULTS

QoL and patient-reported satisfaction were similar between groups. Radiographic evaluation demonstrated no differences in acetabular component positioning; however, mean stem subsidence was 4.6 mm for the MIS anterolateral group and 4.1 mm for the alternate group, with differences observed among the three centers for stem subsidence and fracture. One center had increased rate of fracture requiring treatment and need for revision in the MIS anterolateral group.

CONCLUSIONS

We found no superiority of the MIS anterolateral approach but observed intersite differences in painful stem subsidence and fracture. We have returned to the standard surgical approaches in use before the trial.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

The effects of cam femoroacetabular impingement corrective surgery on lower-extremity gait biomechanics

Surgery to correct cam femoroacetabular impingement (FAI) is increasingly popular. Nevertheless, no known study has analyzed both the three-dimensional lower-extremity joint kinematics and kinetics to quantify FAI surgical outcomes. The purpose of this study was to determine the effects of FAI surgery on the affected lower-extremity joint mechanics during gait by comparing the three-dimensional hip, knee, ankle and pelvic angular displacements, as well as the hip, knee and ankle moments and powers of preoperative and postoperative FAI groups, and a healthy control group. Ten patients with unilateral symptomatic cam FAI, who underwent corrective surgery using an open or combined technique, participated in the biomechanical analysis of level walking preoperatively and postoperatively. Thirteen healthy control subjects provided normative data. Results showed that gait biomechanics of FAI patients did not return to normal after surgery. Postoperatively, patients had reduced hip frontal and sagittal plane ROM, smaller peak hip abduction and internal rotation moments, and decreased peak hip power generation compared to the control group. Despite reductions in hip pain, hip impairments and trends detected preoperatively, perhaps due to modified gait patterns, persisted postoperatively. Additional discrepancies in lower-extremity joint mechanics were observed postoperatively, which are believed to have resulted from partial muscle impairment caused by the surgical approaches. Further research is required to confirm the reasons for which lower-extremity gait mechanics of FAI patients do not return to normal following surgery. Clarifying these causes could help improve surgical techniques and rehabilitation programs for the treatment of FAI, and thus improve surgical outcomes.

The difference between stretching and splitting muscle trauma during THA seems not to play a dominant role in influencing periprosthetic BMD changes

BACKGROUND

Periprosthetic bone adaptation in the proximal femur after total hip arthroplasty can result in reduced bone mineral density that may contribute to increased risk of aseptic loosening or fracture. Functional loading of the proximal femur postoperatively may depend upon the type of surgical muscle trauma - splitting or stretching - and is likely to influence the preservation of periprosthetic bone mineral. Since the maintenance of bone is known to be highly age and gender dependent, the aim of this study was to investigate the interplay between muscle trauma and age and gender influences on periprosthetic bone adaptation.

METHODS

Ninet y-three patients were consecutively recruited into either a transgluteal (splitting) or anterolateral (stretching) surgical approach and examined 7 days and 12 months after an elective primary hip arthroplasty (Zweymüller Alloclassic stem), using dual-energy X-ray absorptiometry measurements to quantify proximal femoral bone mineral density.

FINDINGS

The results indicate that neither gender, age nor surgical trauma type, but only the combination of age and gender, were significant predictors of postoperative remodelling rate, with younger men (<65) and older women exhibiting the largest bone atrophy.

INTERPRETATION

This study has demonstrated that the difference between stretching and splitting surgical trauma to the muscles during total hip replacement does not play a dominant role in influencing periprosthetic bone mineral changes. However, this data does suggest that certain patient populations may particularly benefit from muscle and bone preserving procedures.

[Clinical results of minimally invasive total hip arthroplasty]

AIM

This article presents an analysis and review of recent literature with a focus on clinical results after minimally invasive (MIS) total hip arthroplasty (THA) and with special attention to the different approaches currently used.

METHODS

An online database (Medline) search for clinical trials after THA between 2007 and 2011 was performed with a special focus on prospective controlled randomized trials focusing on THA with a MIS approach. The data were analyzed for pain, blood loss, complications, gait analysis, Harris hip and other scores.

RESULTS

A total of 24 studies (19 comparative studies) were included in this study with a total of 801 MIS THA cases and 695 conventionally operated hips. Almost every study showed superior results for the MIS group with respect to postoperative pain, blood loss and rehabilitation but these advantages almost totally disappeared after 3-6 months. The complication rate was comparable in both groups. After 3-6 months the clinical scores, such as the Harris hip score did not show any differences between conventional and MIS groups.

CONCLUSIONS

In this present study all MIS approaches showed advantages over the conventional surgical approach but these benefits disappeared after 3-6 months. With comparable risks for complications, MIS surgical approaches are superior in the early postoperative phase and rehabilitation.

Measuring functional outcome after total hip replacement with subject-specific hip joint loading

Total hip replacement is an often-performed orthopedic surgical procedure; the amount of procedures undertaken will increase since our life expectancy is growing. In order to optimize function, hip biomechanics should be restored to as near normal as possible. The goal of this pilot study was to determine whether or not it is feasible to compute the vectorial hip reaction force pathways on the head of the prosthesis and the force angles relative to the cup of the prosthesis that occur during gait in total hip replacement patients, serving as an objective measurement of the functional outcome following hip replacement. A three-dimensional gait analysis, measuring ground reaction forces and kinematics, was performed. The data retrieved from the gait analysis was used as the input for the musculoskeletal model to compute vectorial joint reaction forces for data processing. To evaluate the position and orientation of the joint reaction forces, the force path, as well as the force angles for the operated and non-operated joint, has been calculated during the stance phase of the specific leg. The force path for subject 2 on the non-operated side is only located in the posterior-lateral quarter, as is the force path for subject 1. In contrast to this subject, the force path for subject 2 at the operated hip joint can be found only within the anterior quarter of the head of the implant, where it is nearly equally distributed in the medio-lateral half of the prosthesis head. The force-inclination angles on the cup of subject 1, with respect to the plane of the socket face, indicates that the force vector is mainly positioned in the same quadrant when compared with subject 2 (in a cup-fixed coordinate system). The force-anteversion angle behaves similarly to the force-inclination angle, even when the effects are not as pronounced. The proposed methods in this article are aiming to define two functional outcomes of total hip replacement that are related to wear and rim loading. It is accepted that wear is not only a function of time, but a function of use. Owing to the methods listed in this article, we are able to determine a) the applied force and b) the sliding distance (force pathway) in a subject-specific manner. The computed hip-reaction force angles and the distance to the rim cup are a measurement for cup or rim loading, and occurs in the so-called safe-zones. This method may well give us insight into the biomechanical situation during gait, after receiving total hip replacement, that we need to fully understand the mechanisms acting on a hip joint and to prove a possible increase of functional outcome after receiving total hip replacement.

[Minimally invasive surgery in total hip arthroplasty : Surgical technique of the future?]

AIM

A selective analysis of the latest literature was carried out including prospective clinical controlled studies on the comparison between minimally invasive total hip arthroplasty (MIS) and the conventional technique.

METHODS

An online data base search for controlled study designs within the last 3 years (2009-2011) which compared MIS with standard procedures was performed. Data such as operation time, blood loss, Harris hip score, complications and implant positioning were compared.

RESULTS

A total of 11 studies which compared the results of 387 MISs and 264 operations on hips with the standard technique were analyzed. In the majority of the studies reduced levels of creatine kinase and myoglobin as well as reduced intraoperative blood loss were reported. In the early postoperative period up to postoperative week 6 significant advantages in the Harris hip score were reported for the MIS patients. Postoperative complications and implant positioning were comparable in both groups. The operation time was significantly longer in the MIS group for some studies.

CONCLUSIONS

Minimally invasive techniques in total hip arthroplasty are nowadays no longer seen as just cosmetically attractive but rather as a real improvement for the clinical outcome. In this respect prospective clinically controlled studies within the last 3 years showed advantages in the early postoperative period.