Identifying clinically meaningful benchmarks for gait improvement after total hip arthroplasty

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.

Gait pattern in patients treated with a total hip arthroplasty due to an acute displaced cervical neck fracture: a randomised comparison between 29 cases with a cemented femoral stem and 16 cases with an uncemented femoral stem

BACKGROUND

The choice between cemented or uncemented stem fixation in the treatment of a femoral neck fracture may influence patient rehabilitation and the resulting gait pattern, due to potential differences in implant positioning and fixation. We used gait analysis to study temporal gait parameters, hip kinematics and kinetics in patients who, 2 years previously, had been randomised to treatment with a cemented or uncemented stem and due to an acute femoral neck fracture.

METHODS

45 Patients implanted with a cemented Lubinus SP II (n = 29) and an uncemented (n = 16) Corail stem were studied. Gait analysis was performed using a 16-camera motion capture system and force plates. 28 subjects served as controls. Temporal gait parameters, hip kinematics and kinetics were analysed. The patients had no or minimum pain (median Harris pain score 44, range 40-44) and the majority had no limp (median Harris limp score 11, range 5-11).

RESULTS

Temporospatial gait parameters and abduction-adduction motions and moments did not differ between patients with cemented or uncemented stems (p > 0.05). Patients with cemented stems did, however, show more hip flexion and less extension during walking than those with an uncemented stem (p < 0.05). Moreover, the flexion-extension range was less in the cemented group (p < 0.04). Compared with controls, the hip fracture patients walked more slowly, with a shorter stride length and a longer stance phase.

CONCLUSIONS

Increased hip flexion and reduced extension in patients using the Lubinus SP II cemented stem could be an effect of its anteverted neck, but this question requires further study. Despite acute treatment with THA, hip fracture patients demonstrated a change in gait pattern compared with controls 2 years after the operation. This suggests that these changes are caused by the presence of an implant, or the soft-tissue trauma partly caused by the surgery than by any degenerative disease present in patients undergoing elective surgery.ClinicalTrials.gov Identifier: NCT04791605.

Better Mobility Is Associated With Higher Incomes and Longer Working Years Among Older Adults

BACKGROUND

Robust physical mobility is the key to healthy independent aging. Although the association between socioeconomic status and health is well documented, it is unclear whether there is a relationship between mobility and income, because income data are not readily available.

QUESTIONS/PURPOSES

(1) Do individuals with better mobility have higher incomes? (2) Does maintaining mobility over time allow individuals to keep working? (3) Is exercise associated with higher mobility over time?

METHODS

We obtained longitudinal income and health data from the nationally representative Health and Retirement Study. Three cohorts were used. First, we studied the relationship between household income and mobility (on a 6-point index of walking impairment) in 19,430 adults who were assessed in 2016 (representing 93% of the 20,805-person total cohort). We measured the association of mobility and household income in a multivariate linear regression analysis of age, gender, health conditions, and education. We then identified a second group of 1094 individuals with unrestricted mobility in the year 2000 and compared differences in income and working rates between those who maintained mobility and those who lost mobility after 10 years. Finally, we identified a third group of 7063 individuals who were 60 to 80 years old in 2012, divided the group by how often they engaged in exercise, and observed differences in mobility after 4 years.

RESULTS

After adjusting for covariates, a drop of one level of mobility was associated with a USD 3410 reduction in annual household income (95% CI USD 2890 to USD 3920; p < 0.001). After 10 years, individuals who maintained their mobility had incomes that were USD 6500 higher than that of individuals who were not working (95% CI USD 2300 to USD 10,300; p < 0.001) and were more likely to be working (40% versus 34.5%; p < 0.001). Exercising at least once per week was associated with better mobility 4 years later (mobility score 4.46 ± 0.08 versus 3.66 ± 0.08; p < 0.001).

CONCLUSION

Better mobility was associated with more than USD 3000 in annual income. Regular exercise and other interventions that improve mobility may have meaningful returns on investment.

CLINICAL RELEVANCE

Because greater mobility is strongly associated with higher income, orthopaedic interventions may be undervalued.

Revision total hip arthroplasty for aseptic loosening compared with primary total hip arthroplasty for osteoarthritis: long-term clinical, functional and quality of life outcome data

PURPOSE

The aim of this study was the comparative assessment of long-term clinical (subjective and objective), functional and quality of life outcome data between primary and revision THA.

METHODS

122 patients (130 hips) who underwent cementless revision THA of both components (TMT cup, Wagner SL stem, Zimmer Biomet) for aseptic loosening only (Group A) were compared to a matched group of 100 patients (100 hips) who underwent cementless primary THA for osteoarthritis (Synergy stem, R3 cup, Smith & Nephew) (Group B). Outcomes were evaluated with survival analysis curves, Harris Hip Score (HHS), WOMAC, Oxford Hip Score (OHS), Short-Form Health Survey (SF-12) and EQ-5D-5L scales. Mobility was assessed with walking speed, Timed Up And Go Test (TUG), Parker Mobility Score, Lower Extremity Functional Scale (LEFS) and UCLA scores.

RESULTS

At a mean follow-up of 11.1 (8-17) years a cumulative success rate of 96% (95% CI, 96-99%) in Group A and 98% (95% CI, 97-99%) in Group B with operation for any reason as an endpoint was recorded. Statistically significant differences between groups were developed for WOMAC (Mann-Whitney U-test, p = 0.014), OHS (Mann-Whitney U-test, p = 0.020) and physical component of SF-12 scores (Mann-Whitney U-test, p = 0.029) only. Group A had less improvement in function as compared with group B. In Group A, in multiple regression analysis, patients' cognition (p = 0.001), BMI (p = 0.007) and pain (p = 0.022) were found to be independent factors influencing functional recovery (WOMAC). Similarly, pain (p = 0.03) was found to influence quality of life (EQ-5D-5).

CONCLUSIONS

In the long term, revision THA shows satisfactory but inferior clinical, functional, and quality of life outcomes when compared to primary THA. Residual pain, BMI and cognitive impairment independently affect functional outcomes.

Preoperative Lower-Limb Muscle Predictors for Gait Speed Improvement after Total Hip Arthroplasty for Patients with Osteoarthritis

This study aimed to identify preoperative lower-limb muscle predictors for gait speed improvement after total hip arthroplasty (THA) with hip osteoarthritis. Gait speed improvement was evaluated as the subtraction of preoperative speed from postoperative speed. The preoperative muscle composition of ipsilateral hip abductors was evaluated using computed tomography. The females (n = 45) showed smaller total cross-sectional areas of the gluteal muscles than the males (n = 13). The gluteus maximus in the females showed lower lean muscle mass area (LMM) and higher ratios of the intramuscular fat area and the intramuscular adipose tissue area to the total muscle area (TM) than the males. Regression analysis revealed that LMM/TM of the glutei medius and minimus may correlate negatively with postoperative improvement in gait speed. Receiver operating characteristic curve analysis for prediction of minimum clinically important improvement in gait speed at ≥0.32 m/s resulted in the highest area under the curve for TM in the upper portion of the gluteus maximus with negative correlation. The explanatory variables of hip abductor muscle composition predicted gait speed improvement after THA more precisely in the females compared with the total group of both sexes. Preoperative muscle composition should be evaluated separately based on sex for the achievement of clinically important improvement in gait speed after THA.

No difference in gait pattern between a short collum femoris-preserving and a conventional stem: 44 randomised total hip arthroplasty patients stem evaluated after 2 years

BACKGROUND

The uncemented collum femoris-preserving (CFP) stem offers preservation of the femoral neck and a more conservative soft tissue resection, which may facilitate a more normal walking pattern. We used gait analysis to evaluate if patients operated with a CFP stem showed more favourable hip kinematics and kinetics when compared with a group of patients operated with a conventional uncemented stem.

METHODS

44 patients randomised to receive either a CFP or a Corail stem were studied and were operated using a direct lateral incision. Gait analysis was performed 2 years after the operation with a 12-camera motion capture system and 2 force plates. Hip kinematics and kinetics were analysed and 66 subjects served as controls.

RESULTS

None of the variables: speed, stride, cadence and stance showed any statistical significant difference between the 2 study groups. Neither did the hip kinematics and kinetics. Compared to controls, patients operated with the CFP stem showed an increased stance (62.5% vs. 61.1%, p < 0.006) and decreased hip abduction (-2.1° vs. -6.5°). Patients operated with the Corail stem showed decreased speed (1.18 vs. 1.23 m/second), and stride length (1.26 vs. 1.33 m), decreased hip extension (-7.5° vs. -12.8°) and range of hip flexion/extension (38° vs. 40.9°), as well as their hip adduction that was increased (6.3° vs. 4°), whereas their hip abduction was reduced (-2.8° vs. -6.5°), (p < 0.004) compared to the controls.

CONCLUSIONS

Use of a CFP stem did not significantly influence any of the gait parameters studied when compared to a standard stem, but still both stems studied were associated with gait deviations when compared to controls. Whether these differences could be attributed to the stem used, the underlying hip disease, or both is still unknown.

Gluteus Maximus Transfer following Total Hip Arthroplasty Does Not Improve Abductor Moment: A Case-Control Gait Analysis Study of 15 Patients with Gluteus Medius Disruption

Gluteus maximus flap transfer (GMT) is a surgical technique used to improve gait kinematics and kinetics, as well as to reduce and ameliorate the functional outcome in patients with hip abductor deficiency following total hip arthroplasty (THA). The purpose of this observational study was to evaluate the gait pre- and postoperatively and examine whether GMT increases the abduction moment. Materials and Methods: A gait analysis based on reflective markers and force plates was performed in 15 patients who underwent GMT and were examined using an optical tracking system before and at a minimum of 13 months after the operation. The median follow-up time was 24 (13−60) months. The primary outcome was hip abduction moment (Nm/kg) during gait. The control group consisted of 15 female subjects without any gait pathology. Results: The mean adduction moment was significantly higher compared with controls before the operation (p = 0.02), but this did not apply to the abduction moment (p = 0.60). At the group level, the abduction moment did not improve postoperatively (p = 0.30). Only six of fifteen patients slightly improved their hip abduction moment postoperatively. However, speed (0.74 to 0.80 m/s) and cadence (94 to 105 steps/min) were improved (p < 0.03). Discussion: The results of this study showed no improvement in the hip abduction moment after GMT surgery. In our experience, abduction deficiency following primary THA is still a difficult and unsolved problem.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

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

Contralateral Lower-Limb Functional Status Before Total Hip Arthroplasty: An Important Indicator for Postoperative Gait Speed

BACKGROUND

Postoperative gait speed, especially comfortable gait speed, is an important factor for predicting function after total hip arthroplasty (THA). In this study, we examined factors related to gait speed, including preoperative lower and upper-limb functional parameters and postoperative lower-limb alignment. In addition, we examined factors related to postoperative good comfortable gait speed (≥1.34 m/s: one indicator of a good clinical outcome). The purpose of this study was to determine if better preoperative functional parameters had a positive effect on postoperative gait speed.

METHODS

This prospective case-control study included 91 patients with hip osteoarthritis who underwent unilateral THA. Patients who had undergone a prior hip surgical procedure or had Crowe type-3 and 4 hips, complications after THA, knee osteoarthritis-related pain, and severe lumbar conditions were excluded. The 1-leg standing time (OLST) and knee extensor strength of the operatively treated side and the contralateral side and the functional reach test were examined preoperatively and at 1 year postoperatively. The leg-length discrepancy and global offset compared with the contralateral side and leg lengthening were examined using 3-dimensional models captured through computed tomographic scans.

RESULTS

The preoperative contralateral side OLST was a significant factor (p < 0.001) for postoperative comfortable gait speed, and the preoperative contralateral-side knee extensor strength was a significant factor (p = 0.018) for postoperative maximum gait speed. Leg-length discrepancy and differences in global offset after THA were not significant factors for postoperative gait speed. The preoperative comfortable gait speed with a cutoff value of 1.115 m/s (area under the receiver operating characteristic curve, 0.690 [95% confidence interval, 0.569 to 0.810]; p = 0.003; sensitivity of 65.5% and specificity of 74.2%) was an independent factor associated with a good postoperative comfortable gait speed. Preoperative contralateral-side OLST was a significant factor (p = 0.027) for preoperative comfortable gait speed.

CONCLUSIONS

The preoperative contralateral-side, lower-limb functional status is a significant factor for postoperative gait speed. Early surgical intervention before the contralateral-side function declines or a preoperative rehabilitation intervention on the contralateral side may improve THA outcome.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Volumetric Bone Mineral Density in Cementless Total Hip Arthroplasty in Postmenopausal Women: Effects on Primary Femoral Stem Stability and Clinical Recovery

BACKGROUND

In cementless total hip arthroplasty, femoral stems should preferably not migrate at all postoperatively. This goal is difficult to achieve in postmenopausal women with impaired bone quality. Here, we explored the clinical importance of initial stem migration, measured by radiostereometric analysis (RSA), in women who underwent quantitative computed tomography (CT) of the involved hip preoperatively.

METHODS

A prospective cohort of 65 postmenopausal women (mean age, 69 years) with hip osteoarthritis and Dorr type-A or B femoral anatomy underwent total hip arthroplasty with implantation of a tapered, single-wedge femoral stem. Volumetric bone mineral density (BMD) was measured using quantitative CT. Femoral stem translation and rotation were measured using model-based RSA within 3 days after the surgical procedure and were repeated at 3, 5, and 11 months. Postoperative recovery parameters included walking speed, walking activity, and patient-reported outcome measures. Subjects were categorized into 2 groups according to the magnitude of initial 5-month stem subsidence (<2 mm or ≥2 mm); RSA outliers (n = 7) were analyzed separately.

RESULTS

Subjects with stem subsidence of ≥2 mm (mean, 3.09 mm [95% confidence interval (CI), 2.70 to 3.47 mm]) had lower intertrochanteric volumetric BMD (p = 0.008). Subjects with subsidence of <2 mm (mean, 0.80 mm [95% CI, 0.51 to 1.09 mm]) had faster improvement of patient-reported outcome measures and exhibited faster walking speed (p = 0.007) and greater walking activity (p = 0.010) at 11 months as well as better Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores (p = 0.002) and RAND 36-Item Health Survey mental component scores (p = 0.006) at 2 years. All cohort stems were osseointegrated at 2 years.

CONCLUSIONS

Femoral stem stability and resistance to subsidence were sensitive to adequate intertrochanteric volumetric BMD. Low intertrochanteric volumetric BMD was associated with greater stem migration. With initial migration, clinical recovery was slower and patient-reported outcome measures were less satisfactory.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Claudicating patients with peripheral artery disease have meaningful improvement in walking speed after supervised exercise therapy

OBJECTIVE

Supervised exercise therapy (SET) is a first-line treatment for patients with peripheral artery disease (PAD). The efficacy of SET is most commonly expressed by significant statistical improvement of parameters that do not clarify how each individual patient will benefit from SET. This study examined the minimal clinically important difference (MCID) in walking speed in claudicating patients with PAD after SET.

METHODS

A total of 63 patients with PAD-related claudication (Fontaine stage II PAD) participated in a 6-month SET program. Self-selected walking speed was measured before and after SET. Distribution and anchor-based approaches were used to estimate the MCID for small and substantial improvement. The ability to walk one block and the ability to climb one flight of stairs questions were chosen as anchor questions from the Medical Outcomes Study 36-item Short Form questionnaire. Receiver operating characteristics curve analyses were performed to detect the threshold for MCID in walking speed after treatment.

RESULTS

The distribution-based method estimated 0.03 m/s as a small improvement and 0.08 m/s as a substantial improvement after SET. Small and substantial improvements according to the anchor question walking one block were 0.05 m/s and 0.15 m/s, respectively. For the climbing one flight of stairs anchor question, 0.10 m/s was a small improvement. Receiver operating characteristics curve analyses identified an increase of 0.04 m/s and 0.03 m/s for improvement based on walking one block and climbing one flight of stairs, respectively.

CONCLUSIONS

We report our findings for the MCID for walking speed among claudicating patients receiving SET. Claudicating patients who increase walking speed of 0.03 m/s or greater are more likely to experience a meaningful improvement in walking impairment than those who do not. The MCID reported in this study can serve as a benchmark for clinicians to develop goals and interpret clinically meaningful progress in the care of claudicating patients with PAD.

Contributing factors to the initial femoral stem migration in cementless total hip arthroplasty of postmenopausal women

In cementless total hip arthroplasty (THA), femoral stems rely on the initial press-fit fixation against cortical bone to achieve osseointegration. Decreased bone mineral density (BMD) in postmenopausal women poses natural difficulties in achieving axial and rotational femoral stem stability. The present study examined contributing demographic, surgery-related and postoperative factors in determining the magnitude of early stem migration prior to osseointegration. A prospective cohort of 65 postmenopausal women with hip osteoarthritis (Dorr type A or B femur anatomy) underwent THA with implantation of an uncemented parallel-sided femoral component. Postoperative femoral stem translation and rotation were measured using model-based radiostereometric analysis. Based on analysis of covariance, which controlled for outliers and randomized antiresorptive treatment with denosumab or placebo, none of the analyzed demographics (including BMI) and surgery-related variables (including the stem-to-canal fil ratio) was associated with stem subsidence. Stem subsidence (mean 1.8 mm, 95% CI 1.2 to 2.4) occurred even in women with normal hip BMD. Total hip BMD and postoperative walking activity (measured three months after surgery) were significantly associated with stem rotation, and height acted as a confounding factor. The effect of walking activity on stem rotation was significant at 5 months (p = 0.0083) and at 11 months (p = 0.0117). This observation confirms the previous results of instrumented hip prostheses on torsional moments affecting stems during daily activities. High-resolution imaging modalities of local bone quality are needed to explore reasons for RSA-measurable stem subsidence even in women with normal hip BMD.

Walking Speed and Maximal Knee Flexion During Gait After Total Knee Arthroplasty: Minimal Clinically Important Improvement Is Not Determinable; Patient Acceptable Symptom State Is Potentially Useful

BACKGROUND

Total knee arthroplasty (TKA) is the operation of choice in patients with end-stage knee osteoarthritis (OA). Up to 1 in 5 patients still encounter functional limitations after TKA, partly explaining patient dissatisfaction. Which gait ability to target after TKA remains unclear. To determine whether Minimal Clinical Important Improvement (MCII) or Patient Acceptable Symptom State (PASS) values could be derived from gait parameters recorded in patients with TKA. And, if so, to define those values.

METHODS

In this ancillary study, we retrospectively analyzed gait parameters of patients scheduled for a unilateral TKA between 2011 and 2013. We investigated MCII and PASS values for walking speed and maximal knee flexion using anchor-based methods: 5 anchoring questions based on perceived body function and patients' satisfaction.

RESULTS

Over the study period, 79 patients performed a clinical gait analysis the week before and 1 year after surgery, and were included in the present study. All clinical and gait parameters improved 1 year after TKA. Nevertheless, changes in gait outcomes were not associated with perceived body function or patients' satisfaction, precluding any MCII estimation in gait parameters. PASS values, however, could be determined as 1.2 m/s for walking speed and 50° for maximal knee flexion.

CONCLUSION

In this study, we found that MCII and PASS values are not necessarily determinable for gait parameters after TKA in patients with end-stage OA. Using anchor questions based on perceived body function and patient's satisfaction, MCII could not be defined while PASS values were potentially useful.

LEVEL OF EVIDENCE

Level III.

Bone Mineral Density and Cortical-Bone Thickness of the Distal Radius Predict Femoral Stem Subsidence in Postmenopausal Women

BACKGROUND

The distal radius is an optional site for evaluation of bone quality in postmenopausal women before cementless total hip arthroplasty. We hypothesized that dual-energy X-ray absorptiometry (DXA) and pulse-echo ultrasonometry of the distal radius may help discriminate subjects at high risk of femoral stem subsidence.

METHODS

A prospective cohort of postmenopausal women with primary hip osteoarthritis underwent total hip arthroplasty with implantation of a parallel-sided femoral stem. Postoperative stem migration was measured using radiostereometric analysis. Preoperatively, subjects had multisite DXA measurement of bone mineral density (BMD) and pulse-echo ultrasonometry of the cortical-bone thickness. The diagnostic abilities of these methods to discriminate <2 mm and ≥2 mm femoral stem subsidence were tested.

RESULTS

The accuracy of the distal radius BMD and cortical-bone thickness of the distal radius were moderate (area under the curve, 0.737 and 0.726, respectively) in discriminating between <2 mm and ≥2 mm stem subsidence. Women with low cortical-bone thickness of the radius were more likely (odds ratio = 6.7; P = .002) to develop stem subsidence ≥2 mm. These subjects had lower total hip BMD (P = .007) and reduced thickness of the medial cortex of the proximal femur (P = .048) with lower middle (P < .001) and distal (P = .004) stem-to-canal fill ratios.

CONCLUSION

Femoral stem stability and resistance to subsidence are sensitive to adequate bone stock and unaltered anatomy. DXA and pulse-echo ultrasonometry of the distal radius may help discriminate postmenopausal women at high risk of stem subsidence.

Lower functioning patients demonstrate atypical hip joint loading before and following total hip arthroplasty for osteoarthritis

Previous studies have established that up to 1 year post total hip arthroplasty (THA), patients do not recover normal function and the magnitude of hip joint loading remains reduced compared to healthy individuals. However, the temporal nature of the loading profile has not been considered to identify individuals who are at a greater risk of poor functional outcomes following THA. This study aimed to determine changes to the profile and magnitude of the resultant hip joint reaction force before and up to 6 months post-primary THA, and factors associated with atypical loading profiles. Hip joint loading was computed using a personalized lower-limb musculoskeletal model in 43 participants awaiting primary THA for osteoarthritis (mean age: SD = 65, 14 years; body mass index: SD = 30, 5 kg/m² ) before and up to 6 months after THA. Atypical, single-peak loading profiles were observed for 11 patients before surgery, where four showed a single peak at 6 months. Patients displaying a single-peak profile walked slower (mean difference: -0.4 m/s) compared to individuals displaying double-peak profile (P = <.001) and had significantly reduced sagittal plane hip range of motion during gait (mean difference -9.6°, P = <.001). Self-reported pain, function, and stiffness did not differentiate between patients with a single or double-peak loading profile. Individuals with a single-peak force profile did not meet the minimal clinically important hip range of motion during gait and would be classified as low-functioning THA patients. Clinical Relevance: The temporal nature of the force profile may help to identify individuals who are at the greatest risk of poor functional outcomes after THA.

Effect of Denosumab on Femoral Periprosthetic BMD and Early Femoral Stem Subsidence in Postmenopausal Women Undergoing Cementless Total Hip Arthroplasty

Antiresorptive denosumab is known to improve the quality and strength of cortical bone in the proximal femurs of osteoporotic women, but its efficacy in preventing periprosthetic bone loss and reducing femoral stem migration has not been studied in women undergoing cementless total hip arthroplasty. We conducted a single-center, randomized, double-blinded, placebo-controlled trial of 65 postmenopausal women with primary hip osteoarthritis and Dorr type A or B proximal femur anatomy. The patients randomly received subcutaneous injections of denosumab 60 mg or placebo once every 6 months for 12 months, starting 1 month before surgery. The primary endpoint was the change in bone mineral density (BMD) of the proximal femur (Gruen zone 7) at week 48, and the secondary endpoint was stem subsidence measured by radiostereometric analysis (RSA) at week 48. Exploratory endpoints included changes in BMDs of the contralateral hip, lumbar spine and distal radius, serum levels of bone turnover markers, walking speed, walking activity, patient-reported outcome measures, and radiographic assessment of stem osseointegration. The participants underwent vertebral-fracture assessment in an extension safety study at 3 years. Denosumab significantly decreased bone loss in the medial femoral neck (zone 7) and increased periprosthetic BMD in the greater trochanteric region (zone 1) and lesser trochanteric region (zone 6). Denosumab did not reduce temporary femoral stem migration. The migration occurred mainly during the settling period (0 to 12 weeks) after implantation of the prosthesis. All of the stems osseointegrated, as evaluated by RSA and radiographs. There were no intergroup differences in functional recovery. Discontinuation of denosumab did not lead to any adverse events. In conclusion, denosumab increased periprosthetic BMD in the clinically relevant regions of the proximal femur, but the treatment response was not associated with any reduction of initial stem migration. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Digital Versus Conventional Rehabilitation After Total Hip Arthroplasty: A Single-Center, Parallel-Group Pilot Study

Background

The demand for total hip arthroplasty (THA) is rising. In the face of rapidly increasing health care costs, ensuring widespread, cost-effective rehabilitation is a priority. Technologies allowing independent home-based rehabilitation may be the key to facilitate access, improve effectiveness, and lower costs of care.

Objective

The aim of this study was to assess the feasibility of a novel artificial intelligence–powered digital biofeedback system following THA and compare the clinical outcomes against supervised conventional rehabilitation.

Methods

This was a single-center, parallel-group pilot study, with an 8-week intervention program. Patients were assessed at baseline, during the program (at 4 and 8 weeks), and 3 and 6 months after surgery. The primary outcome was the Timed Up and Go (TUG) score and secondary outcomes were the Hip dysfunction and Osteoarthritis Outcome Scale (HOOS; a patient-reported outcome) and hip range of motion (ROM).

Results

A total of 66 patients were included: 35 digital physiotherapy (PT) versus 31 conventional. There were no differences at baseline between groups except for lower HOOS quality of life (QoL) subscale scores in the digital PT group. Clinically relevant improvements were noted in both groups at all time points. The digital PT group showed a retention rate of 86% (30/35). Per-protocol analysis revealed a superiority of the digital PT group for all outcome measures. Intention-to-treat analysis revealed the superiority of the digital PT group at all time points for TUG (change between baseline and 4 and 8 weeks: P<.001; change between baseline and 3 and 6 months: P=.001 and P=.005, respectively), with a difference between median changes of −4.79 seconds (95% CI −7.24 to −1.71) at 6 months post-THA. Between baseline and month 6, results were also superior in the digital PT group for the HOOS sports and QoL subscales and all ROM except for standing flexion.

Conclusions

This study demonstrates this novel solution holds promise in rehabilitation after THA, ensuring better clinical outcomes than conventional rehabilitation while reducing dependence on human resources.

Trial Registration

ClinicalTrials.gov NCT03045549; https://clinicaltrials.gov/ct2/show/NCT03045549

Patient characteristics affect hip contact forces during gait

OBJECTIVE

To examine hip contact force (HCF), calculated through multibody modelling, in a large total hip replacement (THR) cohort stratified by patient characteristics such as body mass index (BMI), age and function.

METHOD

132 THR patients undertook one motion capture session of gait analysis at a self-selected walking speed. HCFs were then calculated using the AnyBody Modelling System. Patients were stratified into three BMI groups, five age groups, and finally three functional groups determined by their self-selected gait speed. By means of statistical parametric mapping (SPM), statistical analyses of the 1-dimensional time series were performed to separately evaluate the influence of age, BMI and functionality on HCF.

RESULTS

The mean predicted HCFs were comparable to HCFs measured with instrumented prostheses reported in the literature. The SPM analysis revealed a statistically significant positive linear correlation between BMI and HCF, indicating that obese patients are more likely to experience higher HCF during most of the stance phase, while a statistically significant negative correlation with age was found only during the late swing-phase. Patients with higher functional ability exhibited significantly increased peak HCF, while patients with lower functional ability demonstrated lower HCFs overall and a pathological flattening of the typical double hump force profile.

CONCLUSION

HCFs experienced at the bearing surface are highly dependent on patient characteristics. BMI and functional ability were determined to have the biggest influence on contact forces. Current preclinical testing standards do not reflect this.

Validation of inertial measurement units with optical tracking system in patients operated with Total hip arthroplasty

Background

Patient reported outcome measurement (PROMs) will not capture in detail the functional joint motion before and after total hip arthroplasty (THA). Therefore, methods more specifically aimed to analyse joint movements may be of interest. An analysis method that addresses these issues should be readily accessible and easy to use especially if applied to large groups of patients, who you want to study both before and after a surgical intervention such as THA. Our aim was to evaluate the accuracy of inertial measurement units (IMU) by comparison with an optical tracking system (OTS) to record pelvic tilt, hip and knee flexion in patients who had undergone THA.

Methods

49 subjects, 25 males 24 females, mean age of 73 years (range 51–80) with THA participated. All patients were measured with a portable IMU system, with sensors attached lateral to the pelvis, the thigh and the lower leg. For validation, a 12-camera motion capture system was used to determine the positions of 15 skin markers (Oqus 4, Qualisys AB, Sweden). Comparison of sagittal pelvic rotations, and hip and knee flexion-extension motions measured with the two systems was performed. The mean values of the IMU’s on the left and right sides were compared with OTS data.

Results

The comparison between the two gait analysis methods showed no significant difference for mean pelvic tilt range (4.9–5.4 degrees) or mean knee flexion range (54.4–55.1 degrees) on either side (p > 0.7). The IMU system did however record slightly less hip flexion on both sides (36.7–37.7 degrees for the OTS compared to 34.0–34.4 degrees for the IMU, p < 0.001).

Conclusions

We found that inertial measurement units can produce valid kinematic data of pelvis- and knee flexion-extension range. Slightly less hip flexion was however recorded with the inertial measurement units which may be due to the difference in the modelling of the pelvis, soft tissue artefacts, and malalignment between the two methods or misplacement of the inertial measurement units.

Trial registration

The study has ethical approval from the ethical committee “Regionala etikprövningsnämnden i Göteborg” (Dnr: 611–15, 2015-08-27) and all study participants have submitted written approval for participation in the study.

Different reliability of instrumented gait analysis between patients with unilateral hip osteoarthritis, unilateral hip prosthesis and healthy controls

BACKGROUND

The gait pattern varies within the population and between patient groups with different musculoskeletal diseases. It also varies over time due to various reasons. Three-dimensional gait analysis (3DGA) is frequently used to measure these changes, but the precision of this methodology may vary.

METHODS

We primarily aimed to study the repeatability of hip motion measurements in patients with unilateral osteoarthritis (OA), patients with unilateral total hip arthroplasty (THA) and healthy controls. A secondary aim was to delineate any differences in hip motion during walking between these groups. Ten males and 10 females in each group were recruited. All patients underwent gait assessments using 3DGA recorded by 2 examiners. Data was analysed with comparison of variance and linear regression.

RESULTS

The variability of the extension-flexion recordings was smallest in healthy controls (SD < 7.7°), increased in patients with THA (SD < 11.1°) and was most pronounced in the OA patients (SD < 12.2°). The degree of hip extension-flexion turned out to be the variable that most effectively could separate the controls from the 2 patient groups and the patient groups from each other. One to 2 years after THA the gait pattern was improved but still differed comparing a group of THA from a group of healthy controls.

CONCLUSIONS

Patients with hip osteoarthritis showed the poorest repeatability between gait recordings collected by different examiners, as compared to patients operated with a THA and healthy controls. The walking pattern after THA still differed from healthy controls 1-2 years after the operation.

1-stage bilateral total hip arthroplasty operation in 22 patients with use of short and standard stem length on either side: gait analysis 1 and 2 years after bilateral THA

BACKGROUND

According to previous gait analyses, insertion of a total hip arthroplasty (THA) will improve the range of hip flexion-extension but not to normal. Use of short stems could have a potential to improve the motion by preservation of more bone and muscular attachments. We evaluated whether a short femoral stem resulted in improved hip motion compared to a conventional stem in patients who underwent 1-stage bilateral THA. The most painful hip was randomised to either design and the 2^nd hip was operated with the design not used on the 1^st side.

METHODS

Gait analysis was performed with an optical tracking system in 22 patients. The follow-up was performed 1 and 2 years after the operation. The mean age was 59 (SD 7.7) years and body mass index was 27.7 (SD 4.3). 66 subjects without hip pathology served as controls.

RESULTS

Minimal differences were observed, between or within the 2 different stem designs during gait at the 2 follow-up occasions. Comparison between each of the 2 stem designs and controls at 2 years revealed reduced stride length (p = 0.009), cadence, hip extension (p<0.001) and hip extension-flexion range (p = 0.021) for both designs. Furthermore, the range of hip adduction-abduction (p = 0.046) and hip abduction moment for both designs in the frontal plane was also reduced bilaterally (p<0.001).

CONCLUSIONS

We found no difference in gait parameters between the short and the conventional stem after 1-stage bilateral THA. Although both hip joints were operated at the same time motions and moments did not normalise after bilateral 1-stage operations.

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.

Abnormal loading of the hip and knee joints in unilateral hip osteoarthritis persists two years after total hip replacement

A total hip replacement (THR) is a common and routine procedure to reduce pain and restore normal activity. Gait analysis can provide insights into functional characteristics and dynamic joint loading situation not identifiable by clinical examination or static radiographic measures. The present prospective longitudinal study tested whether 2 years after surgery a THR would restore dynamic loading of the knee and hip joints in the frontal plane to normal. Instrumented gait analysis was performed shortly before surgery and approximately 2 years after THR on 15 unilateral hip osteoarthritis (OA) patients. 15 asymptomatic matched individuals were recruited as healthy controls. Results showed that abnormal joint loading persisted 2 years after THR. The 2nd external knee adduction moment in terminal stance in the affected (-34%, p = 0.002, d = 1.22) and non-affected limb (-25%, p = 0.035, d = 0.81) was lower compared to controls and thus indicated a shift in the knee joint load distribution from medial to lateral. A correlation analysis revealed that a smaller hip range of motion explained 46% of 2nd knee adduction moment alterations. In contrast, the 2nd external hip adduction moment in terminal stance was postoperatively higher in the affected (+22%, p = 0.007, d = 1.04) and non-affected limb (+22%, p = 0.005, d = 1.05). Here, 51% of 2nd hip adduction moment alterations can be explained with a greater hip adduction angle. Patients with a THR may therefore be at higher risk for abnormal joint loading and thus for the development of OA in other joints of the lower extremities. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Influence of Body Mass Index on Sagittal Knee Range of Motion and Gait Speed Recovery 1-Year After Total Knee Arthroplasty

BACKGROUND

The purpose of this prospective study was to investigate the influence of body mass index (BMI) on gait parameters preoperatively and 1 year after total knee arthroplasty (TKA).

METHODS

Seventy-nine patients were evaluated before and 1 year after TKA using clinical gait analysis. The gait velocity, the knee range of motion (ROM) during gait, their gains (difference between baseline and 1 year after TKA), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), quality of life, and patient satisfaction were assessed. Nonobese (BMI <30 kg/m²) and obese patients (BMI ≥30 kg/m²) were compared. Healthy controls were also assessed. Univariate and multivariate linear regression analyses were used to assess the association between gait speed and ROM gains. Adjustment was performed for gender, age, and WOMAC pain improvement.

RESULTS

At baseline, gait velocity and knee ROM were significantly lower in obese compared with those in the nonobese patients (0.99 ± 0.27 m/s vs 1.11 ± 0.18 m/s; effect size, 0.53; P = .021; and ROM, 41.33° ± 9.6° vs 46.05° ± 8.39°; effect size, 0.52; P = .022). Univariate and multivariate linear regressions did not show any significant relation between gait speed gain or knee ROM gain and BMI. At baseline, obese patients were more symptomatic than nonobese (WOMAC pain: 36.1 ± 14.0 vs 50.4 ± 16.9; effect size, 0.9; P < .001), and their improvement was significantly higher (WOMAC pain gain, 44.5 vs 32.3; effect size, 0.59; P = .011).

CONCLUSION

These findings show that all patients improved biomechanically and clinically, regardless of their BMI.

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.