Do gait adaptations during stair climbing result in changes in implant forces in subjects with total hip replacements compared to normal subjects?

Sex-Based Differences and Asymmetry in Hip Kinematics During Unilateral Extension From Deep Hip Flexion

The purpose of this study was to identify side-to-side and sex-based differences in hip kinematics during a unilateral step-up from deep flexion. Twelve (eight men, four women) asymptomatic young adults performed a step ascent motion while synchronized biplane radiographs of the hip were collected at 50 images per second. Femur and pelvis position were determined using a validated volumetric model-based tracking technique that matched digitally reconstructed radiographs created from subject-specific computed tomography (CT) bone models to each pair of synchronized radiographs. Hip kinematics and side-to-side differences were calculated and a linear mixed effects model evaluated sex-based differences. Women were on average 10.2 deg more abducted and 0.2 mm more medially translated than men across the step up motion (p < 0.001). Asymmetry between hips was up to 14.1 ± 12.1 deg in internal rotation and 1.3 ± 1.4 mm in translation. This dataset demonstrates the inherent asymmetry during movements involving unilateral hip extension from deep flexion and may be used provide context for observed kinematics differences following surgery or rehabilitation. Previously reported kinematic differences between total hip arthroplasty and contralateral hips may be well within the natural side-to-side differences that exist in asymptomatic native hips.

Musculoskeletal modeling and movement simulation for structural hip disorder research: A scoping review of methods, validation, and applications

Musculoskeletal modeling is a powerful tool to quantify biomechanical factors typically not feasible to measure in vivo, such as hip contact forces and deep muscle activations. While technological advancements in musculoskeletal modeling have increased accessibility, selecting the appropriate modeling approach for a specific research question, particularly when investigating pathological populations, has become more challenging. The purposes of this review were to summarize current modeling and simulation methods in structural hip disorder research, as well as evaluate model validation and study reproducibility. MEDLINE and Web of Science were searched to identify literature relating to the use of musculoskeletal models to investigate structural hip disorders (i.e., involving a bony abnormality of the pelvis, femur, or both). Forty-seven articles were included for analysis, which either compared multiple modeling methods or applied a single modeling workflow to answer a research question. Findings from studies comparing methods were summarized, such as the effect of generic versus patient-specific modeling techniques on model-estimated hip contact forces or muscle forces. The review also discussed limitations in validation practices, as only 11 of the included studies conducted a validation and used qualitative approaches only. Given the lack of information related to model validation, additional details regarding the development and validation of generic models were retrieved from references and modeling software documentation. To address the wide variability and under-reporting of data collection, data processing, and modeling methods highlighted in this review, we developed a template that researchers can complete and include as a table within the methodology section of their manuscripts. The use of this table will help increase transparency and reporting of essential details related to reproducibility and methods without being limited by word count restrictions. Overall, this review provides a comprehensive synthesis of modeling approaches that can help researchers make modeling decisions and evaluate existing literature.

The Effect of Surgical Approach and Hip Offset Reconstruction on Gait Biomechanics Following Total Hip Arthroplasty

BACKGROUND

This study aimed to examine how hip offset (HO) and surgical approach affect gait biomechanics following total hip arthroplasty (THA).

METHODS

There were 55 THA patients assigned to 3 groups based on surgical approach (ANT: anterior, LAT: lateral, or POS: posterior) and HO difference (large HO: >5 millimeters (mm), small HO; <5 mm, or normal; between +3 mm and -3 mm). Kinematics and kinetics were recorded using motion capture and force plate data. Group differences were assessed using statistical parametric mapping.

RESULTS

The ANT group demonstrated more normal sagittal plane kinematics and kinetics. No frontal plane kinematic differences were found, but the LAT group displayed more normal frontal plane kinetics. The LAT group displayed a slower walking speed than the ANT group, and the LAT and POS groups used a shorter stride/step length than the control group. The large HO group showed fewer differences in sagittal plane kinematics and kinetics than the small HO and normal groups. No frontal plane kinematic differences were observed, but the normal group demonstrated more significant differences than the large HO and small HO groups. No significant differences were found between any of the HO patient groups.

CONCLUSION

Anterior and lateral approaches led to more normal gait biomechanics in sagittal kinematics and frontal kinetics, respectively, but only the ANT group exhibited spatiotemporal gait parameters within normal ranges. Hip offset differences greater or less than 5 mm do not significantly change gait patterns. Surgical approach plays a greater role than HO reconstruction in producing more normal gait biomechanics following THA.

Similar Biomechanical Behavior in Gait Analysis between Ceramic-on-Ceramic and Ceramic-on-XLPE Total Hip Arthroplasties

In vitro measurements are widely used to implement gait kinematic and kinetic parameters to predict THA wear rate. Clinical tests of materials and designs are crucial to prove the accuracy and validate such measurements. This research aimed to examine the effect of CoC and CoXLPE kinematics and kinetics on wear during gait, the essential functional activity of humans, by comparing in vivo data to in vitro results. Our study hypothesis was that both implants would present the same hip joint kinematics and kinetics during gait. In total, 127 unilateral primary cementless total hip arthroplasties were included in the research. There were no statistically significant differences observed at mean peak abduction, flexion, and extension moments and THA kinematics between the two groups. THA gait kinematics and kinetics are crucial biomechanical inputs associated with implant wear. In vitro studies report less wear in CoC than CoXLPE when tested in a matched gait kinematic protocol. Our findings confirm that both implants behave identically in terms of kinematics in a clinical environment, thus strengthening CoC advantage in in vitro results. Correlated to all other significant factors that affect THA wear, it could address in a complete prism the wear on CoC and CoXLPE.

BIOMECHANICAL ASSESSMENT OF WEAR IN CERAMIC ON CERAMIC AND CERAMIC ON XLPE THAs

Total Hip Arthroplasty (THA) is an effective treatment for severe hip arthritis, with patients reporting high rates of satisfactory results postoperatively. There are a variety of choices regarding THA implant designs. Ceramic on Ceramic and Ceramic on Highly Cross-Linked Polyethylene (XLPE) THAs are the materials of choice nowadays. The purpose of this study is to review the effect of kinematics and kinetics on wear (in vivo and in vitro testing) that affect wear in Ceramic on Ceramic and Ceramic on XLPE total hip arthroplasties and identify possible advantages amongst them. The study hypothesis was that THA kinematics and/or kinetics, since they directly affect THA wear, could provide data for possible advantages between the examined implant designs. A systematic review of the literature identified no significant evidence for biomechanical advantages between these two prostheses in terms of wear. Further research is proposed with the use of gait analysis systems combined with surface electromyography to further investigate THA biomechanics at a laboratory set up. Wearable sensors technology could also identify detailed biomechanical parameters in more complex daily activities.

Evidence based rehabilitation after hip arthroplasty

BACKGROUND

Hip arthroplasty is considered the treatment of choice to improve the quality of life of patients affected by degenerative arthritis. The post-op rehabilitation regimen, however, is still a matter of debate. The goal of this study was to perform a systematic review of the available best evidence to provide recommendations for rehabilitation after hip arthroplasty.

MATERIALS AND METHODS

Biomedical databases were accessed to identify guidelines, systematic reviews and randomised controlled trials addressing rehabilitation after hip arthroplasty published between 2004 and 2019. Studies were selected and extracted by two independent evaluators with standardised tools.

RESULTS

1 guideline, 8 systematic reviews and 5 randomised controlled trials were included. All included papers were organised according the available evidence of clinical course chronology both in pre- and post-operation rehabilitation up to 6 weeks and thereafter. Although the value of a rehabilitation program after hip arthroplasty is universally recognised, the exact timing and number of sessions is still unknown. A solid literature review allows us to partially answer to this question.

CONCLUSIONS

Evidence-based rehabilitation recommendations are proposed according to literature research findings. Clinical practice is still somewhat dependent on dogma and traditions, highlighting the need for additional high-quality clinical studies to address areas of uncertainty.

The test-retest reliability and concurrent validity of the five times sit to stand test and step test in older adults with total hip arthroplasty

PURPOSE

The aim of the study was to determine the test-retest reliability and concurrent validity of the five times sit to stand test (FTST) and step test (ST) in older adults with total hip arthroplasty (THA).

METHODS

A cross-sectional and prospective study was carried out with 32 unilateral total hip arthroplasty patients. FTST, ST, and Timed Up & Go Test were evaluated at the first evaluation session. The test-retest reliability was evaluated by performing two repetitions of the FTST and ST. Besides, the functional status of the patients was evaluated with the Harris Hip Score (HHS). The test-retest reliability of the FTST and ST were assessed by the intraclass correlation coefficient (ICC). In the concurrent validity analysis, the Pearson correlation coefficient was analyzed. In addition, the standard error of measurement (SEM₉₅) and minimal detectable change (MDC₉₅) values of the FTST and ST were also calculated.

RESULTS

The mean age of the participants was 75.4 ± 10.3 years. The ICC score of FTST, ST (right) and ST (left) were 0.987, 0.908 and 0.846, respectively. SEM₉₅ and MDC₉₅ values of the FTST were 1.05 and 2.91, respectively. FTST was correlated with both the HHS and TUG (r₁ = -0.522, r₂ = 0.730, p < 0.01). SEM₉₅ and MDC₉₅ values of the ST (right) were 0.37 and 1.02, respectively. SEM₉₅ and MDC₉₅ values of the ST (left) were 0.55 and 1.52, respectively. Also, ST (right) was only correlated with TUG (r = -0.654, p < 0.01). ST (right) were correlated with both the HHS and TUG (r₁ = 0.503, r₂ = -0.806, p < 0.01). The degree of correlations was strong.

CONCLUSION

The FTST and ST are valid and reliable performance tests in older adults with primary unilateral THA.

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.

Bilateral High Hip Center Provides Gait Parameters Similar to Anatomical Reconstruction: A Gait Analysis Study in Hip Replacement Patients With Bilateral Developmental Dysplasia

BACKGROUND

Total hip arthroplasty in severe dysplasia is challenging due to diminished periacetabular bone stock and the highly placed femoral head. Although anatomical reconstruction of the hip, with required interventions such as subtrochanteric osteotomy and graft usage, is the main aim of the procedure, good long-term clinical outcomes of the high hip center technique have also been reported. Information regarding the effect of hip center placement on gait characteristics is limited; therefore, the aim of this study is to analyze the differences in gait parameters between the high hip center technique and anatomical reconstruction of the hip.

METHODS

Twenty patients (40 hips) with bilateral Crowe type III-IV developmental dysplasia of the hip who underwent bilateral total hip arthroplasty and completed at least 2 years of follow-up were included. Group 1 comprised 10 patients (20 hips) who underwent anatomical hip center reconstruction, while group 2 comprised 10 patients (20 hips) who underwent high hip center reconstruction. The gait characteristics of patients were examined through markers placed in certain anatomical regions, the cameras placed around, and the force plates embedded in the walking platform.

RESULTS

There was no significant difference in the gait characteristics according to the location of the hip rotation center. The mean temporospatial, kinematic, and kinetic values were similar between the groups. The most prominent difference was in the peak dynamic hip extension, which was lower in group 2 (-9.71° ± 7.46°) compared to group 1 (-6.80° ± 11.44°), although it was not statistically significant (P = .09).

CONCLUSION

The bilateral high hip center technique can provide similar gait characteristics as anatomical reconstruction and may be preferred in particularly difficult cases based on the surgeon's decision.

An observational descriptive cross sectional multicenter study of health related quality of life among Iraqi patients after total hip replacement

Background

Hip replacement is highly effective procedure to decrease pain and disability in patients with hip arthritis and accordingly can affect health related quality of life (HRQOL). Globally, limited studies have reported impact of total hip replacement (THR) on HRQOL and there is no previous reports of HRQOL among Iraqi patients after THR.

Objective

To evaluate HRQOL in patients after THR and to assess impact of sociodemographic characteristics on it if present.

Patients and methods

A multicenter cross sectional study was conducted on 96 patients with THR in Iraq. Sociodemographic characteristics were measured. HRQOL after THR was evaluated using Harris hip score (HHS).

Results

The mean age of patients was 56.76, (13.88) years with a range of 23–90 years. Most of patients were females (52 patients (54.2%). Mean BMI was 44.87(8.07) kg/m² with a range of 28.1–56.7 kg/m². The mean(SD) of HHS was 84.39 (7.25) with minimum score of 61.7 and maximum score 93.8. Sociodemographic characteristics had no statistically significant effect on HRQOL measured by HHS except BMI. For each 1 unit increase in BMI, there is significantly and independently decrease in HHS by −0.276.

Conclusions

THR improved HRQOL. BMI was the only significant independent factor that was negatively correlated with HRQOL.

•

Total hip replacement improved health related quality of life.

•

BMI was the only significant independent factor that was negatively correlated with HRQOL.

•

Age, sex, education, smoking history, duration of THR, and indication of THR were not significantly correlated with HRQOL.

Fear of Falling Restricts Activities of Daily Living after Total Hip Arthroplasty: A One-Year Longitudinal Study

OBJECTIVES

To determine the prevalence and time course in changes regarding the fear of falling and whether there are consequent restrictions in activities of daily living (ADL) after total hip arthroplasty (THA).

METHODS

This is 1-year longitudinal observational study. We recruited ninety-eight patients before and after THA. Fear of falling was assessed for 12 ADLs preoperatively and postoperatively at 3, 6, and 12 months following THA. In addition, we asked patients to answer whether they had refrained from performing each ADL because of fear of falling.

RESULTS

Fifty-two patients were enrolled for the analysis. The total fear of falling score during ADLs decreased with time after THA. The ADLs in which many patients (over 20%) felt fear even at 12 months were using the stairs (25%), sitting and standing from the floor (23%), and walking around the neighborhood (21%). Approximately 10% of patients were restricted in performing ADLs, such as sitting and standing from the floor, because of fear.

CONCLUSIONS

Patients undergoing THA frequently experience fear of falling during some ADLs even at 1 year after the operation, which could cause ADL restrictions.

CLINICAL IMPLICATIONS

Clinicians should evaluate fear of falling and institute rehabilitation programs individually to decrease excessive fear that might lead to ADL restrictions.

The Assessment of Static Balance in Patients after Total Hip Replacement in the Period of 2-3 Years after Surgery

Introduction

The aim of this study was to assess static balance of patients after Total Hip Replacement (THR) compared with the age-matched, asymptomatic control group, considering the subject's gender and the time since the surgery.

Materials and Methods

The Total Hip Replacement (THR) group consisted of 55 subjects (mean age: 56.3 ± 8.7 years) and the control group consisted of 48 subjects (mean age: 58 ± 6.2 years). For the assessment of static balance, a stabilometric force platform was used. All subjects performed two 30-second trials in the double-leg stance position with eyes opened and closed. In the study group, the stabilometric assessment was performed once within the period of 24 to 36 months after the surgery.

Results

Subjects from the study group had significantly increased mediolateral COP velocity in the test with eyes opened, as well as the values of most of the COP parameters (excluding COP path area) in the test with eyes closed, compared to the control group. Higher values of the selected COP parameters were observed in the male subjects from the study group.

Conclusion

In contrast to a number of papers, our study revealed some deficits in static balance in patients after THR up to 2-3 years after surgery.

Does the Dual-Mobility Hip Prosthesis Produce Better Joint Kinematics During Extreme Hip Flexion Task?

BACKGROUND

Total hip arthroplasty (THA) using dual-mobility (DM) design permits larger hip range of motion. However, it is unclear how it benefits the patients during activities of daily living. The purpose was to compare kinematic variables of the operated limb between THA patients using either DM or single-bearing (SB) implants during a squat task.

METHODS

Twenty-four THA patients were randomly assigned to either a DM or SB implant and matched to 12 healthy controls (CTRLs). They underwent 3-dimensional squat motion analysis before and 9 months after surgery. Sagittal and frontal plane angles of the pelvis and the hip were analyzed using statistical parametric mapping. Paired analyses compared presurgery and postsurgery squat depth.

RESULTS

Peak sagittal pelvis angle of DM was closer to normal compared with that of SB. Both implant groups had similar hip angle patterns and magnitude but significantly lower than the CTRLs. SB reached a much large hip abduction compared with the other groups. Both surgical groups had significantly worst squat depth than the CTRLs.

CONCLUSION

Neither THA implant groups were able to return pelvis and hip kinematics to the level of CTRLs. The deficit of DM implants at the pelvis combined with the poorer functional scores should caution clinicians to use this implant design in active patients. SB design causes a larger hip abduction to reach their maximum squat depth. Post-THA rehabilitation should focus on improving joint range of motion and strength.

Prediction of Polyethylene Wear Rates from Gait Biomechanics and Implant Positioning in Total Hip Replacement

BACKGROUND

Patient-specific gait and surgical variables are known to play an important role in wear of total hip replacements (THR). However a rigorous model, capable of predicting wear rate based on a comprehensive set of subject-specific gait and component-positioning variables, has to our knowledge, not been reported.

QUESTIONS/PURPOSE

(1) Are there any differences between patients with high, moderate, and low wear rate in terms of gait and/or positioning variables? (2) Can we design a model to predict the wear rate based on gait and positioning variables? (3) Which group of wear factors (gait or positioning) contributes more to the wear rate?

PATIENTS AND METHODS

Data on patients undergoing primary unilateral THR who performed a postoperative gait test were screened for inclusion. We included patients with a 28-mm metal head and a hip cup made of noncrosslinked polyethylene (GUR 415 and 1050) from a single manufacturer (Zimmer, Inc). To calculate wear rates from radiographs, inclusion called for patients with a series of standing radiographs taken more than 1 year after surgery. Further, exclusion criteria were established to obtain reasonably reliable and homogeneous wear readings. Seventy-three (83% of included) patients met all criteria, and the final dataset consisted of 43 males and 30 females, 69 ± 10 years old, with a BMI of 27.3 ± 4.7 kg/m². Wear rates of these patients were determined based on the relative displacement of the femoral head with regard to the cup using a validated computer-assisted X-ray wear-analysis suite. Three groups with low (< 0.1 mm/year), moderate (0.1 to 0.2 mm/year), and high (> 0.2 mm/year) wear were established. Wear prediction followed a two-step process: (1) linear discriminant analysis to estimate the level of wear (low, moderate, or high), and (2) multiple linear and nonlinear regression modeling to predict the exact wear rate from gait and implant-positioning variables for each level of wear.

RESULTS

There were no group differences for positioning and gait suggesting that wear differences are caused by a combination of wear factors rather than single variables. The linear discriminant analysis model correctly predicted the level of wear in 80% of patients with low wear, 87% of subjects with moderate wear, and 73% of subjects with high wear based on a combination of gait and positioning variables. For every wear level, multiple linear and nonlinear regression showed strong associations between gait biomechanics, implant positioning, and wear rate, with the nonlinear model having a higher prediction accuracy. Flexion-extension ROM and hip moments in the sagittal and transverse planes explained 42% to 60% of wear rate while positioning factors, (such as cup medialization and cup inclination angle) explained only 10% to 33%.

CONCLUSION

Patient-specific wear rates are associated with patients' gait patterns. Gait pattern has a greater influence on wear than component positioning for traditional metal-on-polyethylene bearings.

CLINICAL RELEVANCE

The consideration of individual gait bears potential to further reduce implant wear in THR. In the future, a predictive wear model may identify individual, modifiable wear factors for modern materials.

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.

Evaluation of stair motion contributes to new insights into hip osteoarthritis-related motion pathomechanics

Stair motion in the presence of hip osteoarthritis (OA) has received less attention than level walking. Its more strenuous aspect may shed the light on different locomotor strategies when compared to walking. We, therefore, aimed to define stair motion features associated to hip OA and to evaluate whether these specific features would differ from level walking and better characterize the hip pathological condition. Principal component and linear discriminant analyses were, respectively, used as data reduction and classification techniques. Our study highlighted that most of stair motion features associated to hip OA were similar to the ones of walking. Stair descent presented with the lowest misclassification error rate, ranging from 12% to 19% (estimated by cross-validation). But, features that may be considered as a mechanism to reduce demand on the hip abductors were found to be more important in the stair ascent condition. This was reflected by both, greater importance in the classification rule and variance compared with walking, that is, decreased hip internal rotation moment at mid-stance (72.50% vs. 57.63%) and increased trunk lateroflexion toward affected side (56.43% vs. 29.37%). This study emphasized the importance of investigating stair motion in hip osteoarthritic population by highlighting specific locomotor strategies.

In vivo kinematic evaluation of total hip arthroplasty during stair climbing

Stair climbing is a physically demanding task and a painful limitation for patients suffering from severe hip osteoarthritis. Although total hip arthroplasty (THA) is the definitive treatment for end-stage osteoarthritis, it is not well understood whether THA restores hip kinematics during strenuous activities. The purpose of this study was to compare the 3D kinematics of THA and native hip during physically demanding tasks and correlate potential differences with THA components orientations/positions in patients with unilateral THA. In vivo hip kinematics were determined during step-up and leg stance activities using a validated combination of 3D CT-based computer modeling and dual fluoroscopic imaging system (DFIS). The THA side demonstrated an average 3.4° (±6.5°, range: -5.9° to 15.2°) greater internal rotation than the contralateral native hip, during the step-up activity but not during leg stance. The difference in internal rotation was highly correlated to the difference in femoral anteversion and anterior translation of hip joint center between implanted and native hip (R(2)  = 0.71, p < 0.01). The results suggest the importance of accurate THA component placement in restoring normal hip kinematics during functional activities.

Hip contact forces in asymptomatic total hip replacement patients differ from normal healthy individuals: Implications for preclinical testing

BACKGROUND

Preclinical durability testing of hip replacement implants is standardised by ISO-14242-1 (2002) which is based on historical inverse dynamics analysis using data obtained from a small sample of normal healthy individuals. It has not been established whether loading cycles derived from normal healthy individuals are representative of loading cycles occurring in patients following total hip replacement.

METHODS

Hip joint kinematics and hip contact forces derived from multibody modelling of forces during normal walking were obtained for 15 asymptomatic total hip replacement patients and compared to 38 normal healthy individuals and to the ISO standard for pre-clinical testing.

FINDINGS

Hip kinematics in the total hip replacement patients were comparable to the ISO data and the hip contact force in the normal healthy group was also comparable to the ISO cycles. Hip contact forces derived from the asymptomatic total hip replacement patients were comparable for the first part of the stance period but exhibited 30% lower peak loads at toe-off.

INTERPRETATION

Although the ISO standard provides a representative kinematic cycle, the findings call into question whether the hip joint contact forces in the ISO standard are representative of those occurring in the joint following total hip replacement.

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.

Block-step asymmetry 5 years after large-head metal-on-metal total hip arthroplasty is related to lower muscle mass and leg power on the implant side

BACKGROUND

Metal-on-metal articulations mimic the human hip anatomy, presumably lower dislocation rates and increase the range-of-motion. This study aims to measure the muscle mass and power of both legs in patients with unilateral metal-on-metal total hip arthroplasty, and to investigate their effect on block-step test, spatio-temporal gait parameters and self-reported function.

METHODS

Twenty-eight patients (7 women), mean age 50 (28-68) years, participated in a 5-7 year follow-up. Patients had received one type unilateral large-head metal-on-metal total hip articulation, all of which were well-functioning at follow-up. Mean muscle mass was measured by the total-body Dual energy X-ray Absorption scans, and muscle power was measured in a leg extensor power rig. Block-step test and spatio-temporal gait parameters were measured with an inertial measurement unit. Self-reported function was assessed by the Hip Disability and Osteoarthritis Outcome Score.

FINDINGS

We found a significant difference between the mean muscle mass of the implant-side leg and the non-implant-side leg in hip, thigh and calf areas (P<0.008) and in mean muscle power (P=0.025). Correlations between mean muscle mass and mean muscle power were significant for both the implant-side leg (r=0.45, P=0.018) and the non-implant-side leg (r=0.51, P=0.007). The difference in mean muscle power between legs correlated with block-step test asymmetry during ascending (r=0.40, P=0.047) and descending (r=0.53, P=0.006). Correlations between self-reported function and power of the implant-side leg were not significant.

INTERPRETATIONS

Young patients have not fully regained muscle mass, muscle power and function 5-7 years after metal-on-metal total hip arthroplasty.

Assessment of asymmetric leg loading before and after total hip arthroplasty using instrumented shoes

Background

Total hip arthroplasty is a successful surgical treatment in patients with osteoarthritis of the hip. Different questionnaires are used by the clinicians to assess functional capacity and the patient's pain, despite these questionnaires are known to be subjective. Furthermore, many studies agree that kinematic and kinetic parameters are crucial to evaluate and to provide useful information about the patient’s evolution for clinicians and rehabilitation specialists. However, these quantities can currently only be obtained in a fully equipped gait laboratory. Instrumented shoes can quantify gait velocity, kinetic, kinematic and symmetry parameters. The aim of this study was to investigate whether the instrumented shoes is a sufficiently sensitive instrument to show differences in mobility performance before and after total hip arthroplasty.

Methods

In this study, patients undergoing total hip arthroplasty were measured before and 6–8 months after total hip arthroplasty. Both measurement sessions include 2 functional mobility tasks while the subject was wearing instrumented shoes. Before each measurement the Harris Hip Score and the Traditional Western Ontario and McMaster Universities osteoarthritis index were administered as well.

Results

The stance time and the average vertical ground reaction force measured with the instrumented shoes during walking, and their symmetry index, showed significant differences before and after total hip arthroplasty. However, the data obtained with the sit to stand test did not reveal this improvement after surgery.

Conclusions

Our results show that inter-limb asymmetry during a walking activity can be evaluated with the instrumented shoes before and after total hip arthroplasty in an outpatient clinical setting.

Fear of falling during activities of daily living after total hip arthroplasty in Japanese women: a cross-sectional study

OBJECTIVES

To investigate the prevalence of fear of falling, and identify factors associated with fear of falling during activities of daily living after total hip arthroplasty (THA).

DESIGN

Cross-sectional study.

SETTING

Community.

PARTICIPANTS

Two hundred and fourteen women who had undergone THA.

MAIN OUTCOME MEASURES

Fear of falling after THA was assessed for 12 activities of daily living using a fear of falling score. The number of falls in the past year, total Oxford Hip Score (OHS), total Penn State Worry Questionnaire (PSWQ) score and walking capacity were recorded as descriptive statistics. Multiple linear regression analysis was performed, with total fear of falling score as the dependent variable and age, body mass index, time since THA, bilateral THA, total OHS, history of falling, walking capacity and total PSWQ score as the independent variables.

RESULTS

A number of participants (mean age = 64.2) experienced fear of falling while ascending and descending stairs: 45% (97/214), taking a bath: 26% (56/214), bending to pick something up off the floor: 26% (55/214), and getting up from lying on the floor: 25% (54/214). Fear of falling during activities of daily living after THA was significantly correlated with total OHS, history of falling, walking capacity, total PSWQ score and age (P<0.05).

CONCLUSIONS

Fear of falling develops in certain activities of daily living after THA. It is associated with poorer functional outcome, history of falling, lower walking capacity, higher anxiety level and older age.

Concurrent assessments of lower limb loading patterns, mechanical muscle strength and functional performance in ACL-patients--a cross-sectional study

BACKGROUND

Full recovery in muscle strength and functional performance may not be achieved after ACL-injury.

AIM

The aim of this study is to investigate loading patterns during jumping, muscle function and functional performance in ACL-reconstructed patients and to investigate the origin of between-limb asymmetry by means of a 3-dimensional movement analysis. Design is cross-sectional.

METHODS

23 ACL-reconstructed men (27.2±7.5 years, BMI: 25.4±3.2) 27±7 month post-surgery and 25 matched controls (27.2±5.4 years, BMI: 24.1±1.8) were included. Participants performed (i) bilateral and (ii) unilateral counter movement jumps (CMJ). A 3-D movement analysis was performed by a six-camera Vicon MX-system. Subsequently, jump height (JH), knee joint range of motion (ROM), peak and mean sagittal knee moments were analyzed (iii) one-leg maximal jump for distance was performed, and (iv) maximal unilateral isometric knee extensor and flexor strength (MVC) were measured using stabilized dynamometry.

RESULTS

No in-between group differences in age or BMI were observed. CMJ: Between-limb asymmetry ratios for ROM differed (p<0.01) between patients and controls in both types of CMJ (96.1% vs. 102.6% and 87.0% vs. 99.9% in bilateral and single-leg CMJs, respectively). Jump for distance: Patients demonstrated greater (p<0.01) asymmetry for jump length (92.9% vs. 98.6%). MVC: Asymmetry in hamstring MVC was greater (p<0.001) for patients than controls (77.4% vs. 101.3%).

CONCLUSIONS

ACL-patients showed reduced function of the operated leg~2 years post ACL-reconstruction, especially for hamstring MVC. Hamstrings are important protagonists to the ACL, thus representing a potential risk factor for secondary ACL-rupture and/or osteoarthritis.

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.

Stair ascending and descending in hip resurfacing and large head total hip arthroplasty patients

Large head total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) are alternatives to standard THA that generally have head sizes larger than 36mm. This study examined 20 patients (10 large head THA and 10 HRA), at an average of 18months postoperatively, and 15 healthy control subjects during stair negotiation. Hip kinetic and kinematic variables and ground reaction forces were measured. The THA and HRA groups ascended the stairs with increased peak hip flexion angles and decreased hip extension angles as compared with controls. The operative groups also descended the stairs with decreased hip flexion moments. No differences between the operative groups were observed. Eighteen months postoperatively, patients with large head THA or HRA display abnormal flexion and extension during a physically-demanding task.

Preoperative prediction of ambulatory status at 6 months after total hip arthroplasty

BACKGROUND

Total hip arthroplasty (THA) is an effective procedure that provides patients with long-term relief from pain and enables them to resume their normal daily activities. Preoperative instruction about the functional outcomes and optimum goal of rehabilitation is helpful for patients undergoing THA.

OBJECTIVE

The purposes of this study were: (1) to examine the relationships between preoperative physical functions and ambulation following THA and (2) to identify optimal cutoff values for estimating ambulatory status at 6 months after THA.

DESIGN

This was a retrospective study.

METHODS

The study participants were 204 patients who underwent a unilateral THA. Hip abductor and knee extensor strength were measured and the Timed "Up & Go" Test (TUG) was conducted preoperatively. The patients were divided into 2 groups according to self-reported walking ability at 6 months postoperatively: an independent ambulation group (n=118) and a cane-assisted ambulation group (n=86). Differences between the 2 groups were examined using an unpaired t test or the chi-square test. A stepwise multiple logistic regression analysis was performed with walking ability at 6 months postoperatively as a dependent variable and age, sex, contralateral hip osteoarthritis (ie, whether a participant had contralateral hip osteoarthritis or not), body mass index, hip abductor strength, knee extensor strength, and TUG score as independent variables. Receiver operating characteristic curve analysis was used to identify a cutoff point for classifying the participants into the 2 groups.

RESULTS

A stepwise multiple logistic regression analysis selected 3 factors (age, knee extensor strength, and TUG score) as significant variables affecting the midterm ambulatory ability after THA. Moreover, receiver operating characteristic curve analyses revealed that the midterm (ie, 6-month) ambulatory status after THA was more accurately predicted by the patient's TUG score (cutoff point=10 seconds, sensitivity=76.7%, specificity=93.2%, area under the curve=0.93) than by age and knee extensor strength.

LIMITATIONS

The categorization of ambulatory status in this study was based solely on self-reported walking ability.

CONCLUSION

The findings indicate that patients with a preoperative TUG score of less than 10 seconds are likely to walk without an assistive device at 6 months after THA.

Lower-limb joint mechanics after total hip arthroplasty during sitting and standing tasks

While the effect of total hip arthroplasty on the operated limb mechanics is well documented, little is known on its effect on the contralateral limb. The purpose of this study was to measure the joint mechanics of both lower limbs during the tasks of sit-to-stand and stand-to-sit. Twenty total hip arthroplasty patients and 20 control participants performed three trials of each task from which 3D lower-limb joint kinematics and kinetics were obtained. Total hip arthroplasty patients exhibited lower operated-hip joint flexion, extension moments, and power, occurring most frequently near seat-on and seat-off. Despite these reduced kinetic variables in the operated hip, the joints of the non-operated limb generated similar joint kinetics as the matched control participants. These results indicated the patients who underwent total hip arthroplasty could adopt a strategy that allowed them to reduce moments and power generated at the operated lower-limb joints without overcompensating with the non-operated leg. Although such a strategy may be desirable given that higher loads can increase friction and accelerate wear of the prosthesis, reduced loading may be an indication of inadequate muscle strength that needs to be addressed.

Does the anterior approach for total hip arthroplasty better restore stair climbing gait mechanics?

While total hip arthroplasty (THA) provides pain relief and restores mobility, gait anomalies persist even years after surgery. A muscle sparing surgical approach could result in better postoperative gait mechanics. Our purpose was to compare both the anterior muscle sparing approach and the direct lateral approach (LAT) to a matched control group by using three-dimensional motion analysis while performing stair ascent and descent tasks. Lower-limb kinematics and kinetics were recorded for 20 patients that had an anterior approach (ANT), 20 that had a LAT, and 20 age- and weight-matched control participants. Patients were assessed on average 10 months after surgery. Compared to the control group, during stair ascent, the anterior group had reduced peak hip extension, peak hip flexion moment, and peak hip power. The lateral group had reduced peak hip abduction, hip frontal plane range of motion, and peak hip internal rotation. In stair descent, the anterior group had reduced peak hip flexion, peak hip abduction moment and internal rotation, as well as peak hip power. The lateral group had reduced peak hip flexion, peak knee extension moment, and peak hip power. Therefore, gait anomalies persist after THA for both approaches, which could be due to other factors such as preoperative gait adaptations.

Prediction of ambulation ability following total hip arthroplasty

BACKGROUND

In early postoperative rehabilitation after THA, it is essential to clarify some factors related to future ambulation ability. The aim of this study was to examine whether it is possible to predict ambulation ability for patients with THA at 6 months postoperatively.

METHODS

The subjects of this study were 123 patients who had undergone unilateral THA. The hip abductor and knee extensor strength was assessed, and a timed up and go (TUG) test was performed at 4 weeks after the operation. Then, the patients were divided into two groups according to their ability to walk and to go up and down stairs at 6 months postoperatively: the good ambulatory group (n = 64) and the non-good ambulatory group (n = 59).

RESULTS

The discriminating criteria between the two groups were 0.47 (Nm/kg) for hip abductor strength, 1.07 (Nm/kg) for knee extensor strength, and 10 s for TUG test. By multiple logistic regression, knee extensor strength and TUG test at 4 weeks were significantly associated with the categorization at 6 months.

CONCLUSIONS

The results of this study suggest that the TUG test and knee extensor strength at an early stage after THA were useful indicators for predicting patients' ambulation ability at 6 months postoperatively.

Comparison of joint mechanics of both lower limbs of THA patients with healthy participants during stair ascent and descent

Total hip arthroplasty (THA) is a common surgical procedure for patients suffering from osteoarthritis to relieve their pain and to attempt to restore their normal locomotion patterns. Although this procedure does not restore normal mobility during activities of daily living, it remains unclear how it affects the joint mechanics of both lower limbs during stair negotiation tasks. Hence, we compared the 3D joint mechanics of both lower limbs of THA patients with matched healthy controls during stair ascent and stair descent. 3D kinematics and kinetics of both lower limbs were recorded for 20 patients having undergone unilateral THA and 20 healthy, age and body mass index matched control participants. The THA patients generated limited power at the operated hip joint, and thus compensated with larger power generation at the contralateral ankle to lift the body weight to the next step. This stair ambulation strategy, as well as others, adopted by the THA patients implied decreased activation of the lower limb musculature, which may be indicative of a muscle strength deficiency or a post-operatively adopted protective mechanism to unload the prosthesis. These asymmetric power production patterns should be addressed in rehabilitation programs pre- and post-operatively.

Gait and motion analysis of the lower extremity after total hip arthroplasty: what the orthopedic surgeon should know

This article presents critical issues related to the interpretation of biomechanical findings of the hip joint for patients having undergone hip arthroplasty. The use of a gait, or biomechanical, analysis provides objective evidence of the efficiency of the treatments or the effectiveness of hip replacement approaches. Based on our biomechanical analysis, patients who have undergone total hip arthroplasty use a stair ascent and descent strategy allowing them to significantly reduce loading at the prosthetic hip joint. Since hip joint reaction forces are highly dependent on muscle activation, the THA group have adopted a neuromuscular control strategy that is enabling them to reduce loading on the prosthetic hip joint. It could also be a joint loading pattern that stems from a muscular deficiency emerging either from several years of loading avoidance on the affected hip joint or from the surgical procedure. Therefore, a biomechanical analysis of human motion is a valuable tool for the orthopedic surgeon to objectively quantify joint motion and the forces producing this motion.

Gait and stair function in total and resurfacing hip arthroplasty: a pilot study

Standard total hip arthroplasty (THA) is the established surgical treatment for patients older than 65 years with progressive osteoarthritis but survivorship curves wane in patients younger than 50. Resurfacing hip arthroplasty (RHA) is an alternative for younger, active patients reportedly providing superior range of motion. Quantitative investigation of functional recovery following arthroplasty may elucidate limitations that aid in device selection. Although limited long-term kinematic data are available, the early rate of recovery and gait compensations are not well described. This information may aid in refining rehabilitation protocols based on limitations specific to the implant. We presumed hip motion and forces for subjects receiving RHA are more similar to age-matched controls during physically demanding tasks, such as stair negotiation, at early time points than those for THA. In a pilot study, we quantified walking and stair negotiation preoperatively and 3 months postoperatively for seven patients with RHA (mean age, 49 years), seven patients with standard THA (mean age, 52 years), and seven age-matched control subjects (mean age, 56 years). Although both treatment groups demonstrated trends toward functional recovery, the RHA group had greater improvements in hip extension and abduction moment indicating typical loading of the hip. Further investigation is needed to determine if differences persist long term or are clinically meaningful.