Changes in hip and knee muscle strength in patients following total hip arthroplasty

Relevance of physical activity with decrease in minimal joint space of the nonoperative hip in female patients after unilateral THA

To clarify the relevance of physical activity (PA) with respect to a decrease in minimal joint space (MJS) of the nonoperative hip in female patients at 24 months post-contralateral total hip arthroplasty (THA). This prospective cohort study was conducted from six to 24 months post-THA. The subjects were 85 female patients with hip osteoarthritis (OA) who had undergone unilateral THA. The primary outcome was a change in MJS (ΔMJS). Daily step counts and moderate to vigorous physical activity were measured. To identify factors related to ΔMJS, a generalized linear model approach was used, with adjustment factors, Kellgren-Lawrence (KL) grade, PA, and interaction terms between PA and KL grade as explanatory variables. The interaction term between daily step count and KL grade was significant. The regression coefficient of the daily step count for ΔMJS was significant in the KL ≥ 1 group, but not in the KL = 0 group. A model with adjustment factors, an interaction term, and PA showed that the daily step count increased ΔMJS. PA was related to ΔMJS of the nonoperative hip in female patients with KL grade ≥1, but was not related to ΔMJS in patients without OA post-THA. Excessive daily step count may be a risk factor for a decrease in MJS of the nonoperative hip.

No difference in early functional outcome between the direct anterior approach and posterior approach in patients following total hip arthroplasty

BACKGROUND

Objective and subjective outcomes in the direct anterior approach (DAA) and posterior approach (PA) in total hip arthroplasty (THA) were assessed in this study, using the Oxford Hip Score (OHS) as primary outcome. Pain, 3 objective performance-based tests, surgical time, blood loss and length of stay were assessed as secondary outcomes.

METHODS

Patients with primary end-stage osteoarthritis were prospectively enrolled by shared decision making for the DAA (32 patients) or PA (26 patients). Baseline data were collected preoperatively and outcomes postoperatively at 2-, 6-, 9- and 12-month follow-up.

RESULTS

There is no significant difference (p < 0.05) between the DAA and PA on primary outcome (OHS). There was a main effect of time which indicated an increase of OHS over time independent of group (p < 0.01).

CONCLUSIONS

In the current study, no significant differences in postoperative functional outcome were found between DAA and PA in all follow-up moments.

Identifying Deficits in Hip and Knee Muscle Strength on the Surgical and Nonsurgical Sides in Women up to 12 Months After Total Hip Arthroplasty

OBJECTIVE

Regaining hip and knee muscle strength is important after total hip arthroplasty (THA). However, it is unclear if muscles other than those of the operated hip also lose strength. This study aimed to identify deficits in hip and knee strength on the surgical and nonsurgical sides in female patients up to 12 months after THA.

METHODS

Participants were 91 female patients who had hip osteoarthritis and underwent unilateral THA. Forty-six community-dwelling women who were asymptomatic were selected as control participants. Patients with locomotor disorders or postsurgical complications were excluded. Maximal isometric strength of the hip flexors, extensors, and abductors and knee extensors and flexors on the surgical and nonsurgical sides were measured before THA and 3, 6, and 12 months thereafter.

RESULTS

Twelve months after THA, hip flexion, extension, and abduction strength on the surgical side were 84.6%, 83.5%, and 76.2%, respectively, of those in individuals who were asymptomatic; at the same time point, those on the nonsurgical side were 94.8%, 83.9%, and 79.4%, respectively. Knee extension strength on the surgical side was 89.3% of that in individuals who were asymptomatic. Compared to individuals who were asymptomatic, nearly all muscles showed significantly lower strength on both sides up to 6 months after THA.

CONCLUSION

At 12 months after THA, hip and knee strength on both the surgical and nonsurgical sides did not recover to the level observed in individuals who were asymptomatic. In particular, hip abductor strength on the surgical and nonsurgical sides were 76% and 79%, respectively, of that in individuals who were asymptomatic.

IMPACT

At 12 months after THA, hip and knee strength on the surgical and nonsurgical sides did not recover to the level observed in individuals who were asymptomatic, suggesting that the nonsurgical side may be inappropriate as a control to assess strength recovery on the surgical side.

Recovery of Muscular Strength Following Total Hip Replacement: A Narrative Review

This narrative review analyzes muscle strength recovery following total hip replacement (THR) and looks at various factors affecting postoperative muscle function restoration. The review synthesizes evidence from various studies regarding the timing and degree of muscular strength recovery, different rehabilitation protocols, and patient-specific variables such as age, preoperative physical condition, and comorbidities, among others. Overall, it appears that THR is associated with improved hip function and quality of life, but this usually takes a long time due to individualized physical therapy interventions. In addition, postoperative rehabilitation has been found not to exist without any personal factors involved such as age or gender whereby for instance senior citizens have no alternative but to go for THR surgery, making their lower limbs weaker than those who are younger. Based on the findings in this review on muscle recovery after THR surgeries, one may conclude that this endeavor should begin as early as possible and include regular resistance training programs with performance-focused functional training after surgery. In addition, more longitudinal studies should be conducted regarding post-surgical outcomes comparing other traditional medical practices.

Does self-reported physical activity relate to physical function and walking ability in female patients with hip osteoarthritis? A cross-sectional multicenter study

BACKGROUND

The effectiveness of a high level of physical activity in maintaining physical function in patients with hip osteoarthritis has not been adequately examined.

OBJECTIVE

This study aimed to determine whether self-reported physical activity is associated with physical function and walking ability in female patients with hip osteoarthritis.

METHODS

This was a multicenter cross-sectional study. The dependent variables were the lower-limb range of motion and muscle strength, and walking ability. Self-reported physical activity was assessed according to the guidelines of the Japanese Ministry of Health, Labor, and Welfare. Multiple regression models were used to determine whether physical activity was significantly related to the dependent variables after adjusting for confounding factors (age, body mass index, hip pain, comorbidity, and severity of hip osteoarthritis).

RESULTS

A total of 167 participants were included in the study. Physical activity was associated with muscle strength in hip flexion (affected/unaffected, β = 0.18/β = 0.16), abduction (β = 0.19/β = 0.26), knee extension (β = 0.22/β = 0.26), Timed Up-and-Go test (β = -0.16), and 5-m walking time test (β = -0.15).

CONCLUSION

In female patients with hip osteoarthritis, greater physical activity was associated with greater lower extremity muscle strength and walking ability.

Early Recovery of Physical Function After Total Hip Arthroplasty in a Patient With Osteopetrosis: A Case Report

Osteopetrosis is an uncommon and inherited disorder. Some disease-specific characteristics, such as diffuse osteosclerosis and a high incidence of fractures, may potentially affect postoperative rehabilitation. This report presents a case of successful rehabilitation early after total hip arthroplasty for osteopetrosis. A 56-year-old Japanese man, who was diagnosed with osteopetrosis at the age of 11, underwent total hip arthroplasty in the right hip. Full weight-bearing was allowed on the day after the operation; the postoperative rehabilitation program was proceeded based on a standard program as done after total hip arthroplasty for osteoarthritis. A shoe lift in the left leg was used in supervised walking training to correct the imbalanced alignment due to leg length discrepancy. The patient could walk independently with a cane 17 days after the operation. Three weeks after the operation, the patient demonstrated comfortable and maximal walking speed of 1.11 and 1.34 m/s, respectively, and maximal hip abductor muscle strength of 3.96 kgf･m, both of which were better than those before the operation. There were no adverse events during the postoperative rehabilitation course. These findings suggest the safety and efficacy of standard rehabilitation programs after total hip arthroplasty even in individuals with osteopetrosis. In addition, it may be important to consider the whole-body condition in the rehabilitation of individuals with osteopetrosis.

Cut-off values of preoperative knee extensor strength and hip abductor strength for predicting good walking ability after total knee arthroplasty

INTRODUCTION

Total knee arthroplasty (TKA) reduces pain and improves physical function; however, not all patients have successful outcomes after surgery. To identify these patients would be critical information for improving rehabilitation programs. The purpose of this study was to clarify the cut-off values of lower extremity muscle strength for predicting postoperative good walking ability.

MATERIALS AND METHODS

Timed Up and Go test of 105 patients was measured at 6 months postoperatively, and participants were divided into good (< 9.1 s) and poor (≥ 9.1 s) walking ability. Both sides of knee extensor strength (KES) and hip abductor strength (HAS) were measured using hand-held dynamometer preoperatively. Receiver operating characteristic (ROC) curve analysis was used to identify cut-off values for classifying the participants into the two groups.

RESULTS

Of the 105 patients, 54 were allocated in the poor walking ability group, whereas 51 were allocated in the good walking ability group. KES and HAS were significantly greater in the good walking ability group than in the poor walking ability group. ROC curve analysis revealed that the cut-off value for KES was 0.79 Nm/kg (area under the curve (AUC) 0.68; sensitivity 64.7%; specificity 68.5%) on the involved side and 0.86 Nm/kg (AUC 0.73; sensitivity 84.6%; specificity 55.6%) on the uninvolved side, and for HAS was 0.57 Nm/kg (AUC 0.71; sensitivity 60.8%; specificity 71.7%) on the involved side and 0.61 Nm/kg (AUC 0.76; sensitivity 66.7%; specificity 77.4%) on the uninvolved side.

CONCLUSION

The cut-off values of preoperative KES and HAS for predicting good walking ability after TKA are 0.79 Nm/kg on the involved side and 0.86 Nm/kg on the uninvolved side, and 0.57 Nm/kg on the involved side and 0.61 Nm/kg on the uninvolved side, respectively. We should provide enhanced pre- and post-operative rehabilitation programs for patients with muscle strength lower than these values.

Effects of cross-training on motor function and length of stay after total hip arthroplasty: A randomized controlled trial

BACKGROUND

There is no consensus about which training methods will give better early outcomes after total hip arthroplasty (THA).

OBJECTIVE

To investigate the short-term effects of cross trainer exercise on physical function and walking ability following THA.

METHODS

Fifty patients who underwent THA were randomly allocated into two groups. The intervention program was started 3 days after surgery. The main physical function results were pain, hip range of motion, knee extensor strength, single-leg stance time, and walking performance test. In addition, the number of days of requiring to walk and the length of hospital stay were recorded.

RESULTS

In the comparison between groups at discharge, the patients in the cross trainer group had significantly less hip pain while walking, improvement in knee extensor strength, increased single-leg stance time, as well as increased walking speed and stride length at discharge. The number of days required to walk and length of stay were also significantly lower in the intervention group.

CONCLUSIONS

Conclusions: Cross trainer exercise commencing 3 days postoperatively improves physical function and walking ability after THA.

Effects of social isolation associated with the COVID-19 pandemic on hip muscle strength, hip joint pain, and walking ability in patients with osteoarthritis of the hip joint

To reduce the spread of the Sars-CoV-2 virus, governments in many countries adopted a social isolation strategy. However, social isolation may adversely affect people's health, e.g., by decreasing the muscle function of lower limbs. We recruited 118 patients who had undergone total hip arthroplasty (THA) and 87 patients with moderate to severe hip joint osteoarthritis (OA) and measured hip muscle strength, hip joint pain, and walking ability from before to one year after the start of the COVID-19 pandemic. During the pandemic, hip flexion (straight leg raise, SLR) strength decreased in 13.1% of patients in the post-THA group and 25.6% in the severe-OA group; in the severe-OA group, the decrease in SLR strength was mainly in patients aged 65 years and older. In addition, pain increased to mild or moderate and walkable distance decreased in more patients in the severe-OA group.

Blood Flow Restriction Enhances Rehabilitation and Return to Sport: The Paradox of Proximal Performance

The use of blood flow restriction (BFR) within rehabilitation is rapidly increasing as further research is performed elucidating purported benefits such as improved muscular strength and size, neuromuscular control, decreased pain, and increased bone mineral density. Interestingly, these benefits are not isolated to structures distal to the occlusive stimulus. Proximal gains are of high interest to rehabilitation professionals, especially those working with patients who are limited due to pain or postsurgical precautions. The review to follow will focus on current evidence and ongoing hypotheses regarding physiologic responses to BFR, current clinical applications, proximal responses to BFR training, potential practical applications for rehabilitation and injury prevention, and directions for future research. Interestingly, benefits have been found in musculature proximal to the occlusive stimulus, which may lend promise to a greater variety of patient populations and conditions. Furthermore, an increasing demand for BFR use in the sports world warrants further research for performance research and recovery.

LEVEL OF EVIDENCE

Level V, expert opinion.

Relationship between early physical activity after total knee arthroplasty and postoperative physical function: are these related?

Background

Physical activity is associated with physical function; however, the relationship between early physical activity after total knee arthroplasty (TKA) and postoperative physical function remains unclear. The purpose of this study was to evaluate the association of early physical activity after TKA with postoperative physical function.

Methods

Timed Up and Go test (TUG) of 47 patients was assessed preoperatively and at 10 days, 3 months, and 6 months postoperatively. Physical activity from the second to the ninth day after TKA was measured with accelerometer, and the correlation with pre- and postoperative physical function was evaluated . A multiple linear regression was used to predict TUG at 6 months after TKA.

Results

Postoperative physical activity correlated with preoperative TUG (ρ = −0.485, p < 0.001), TUG at 10 days (ρ = −0.675, p < 0.001), 3 months (ρ = −0.441, p < 0.01), and 6 months (ρ = −0.368, p < 0.05) after surgery. Multiple linear regression indicated that only the preoperative TUG was associated with TUG at 6 months. Postoperative physical activity was not an independent factor predicting TUG at 6 months after TKA.

Conclusion

Our study demonstrated that patients with better physical function have higher physical activity in the early postoperative period, whereas it does not affect physical function at 6 months after TKA. In the early postoperative period, increasing physical activity may not always be necessary to improve postoperative physical function. We also confirmed that preoperative physical function affects postoperative physical function. These findings may be beneficial in improving rehabilitation programs in the early postoperative period.

A predictive model for hip abductor strength and knee extensor strength 12 months after total hip arthroplasty with an interaction term

Background

Identifying populations with poor muscle recovery after total hip arthroplasty (THA) is important for postoperative physical therapy. Preoperative muscle strength is a strong factor that determines postoperative muscle strength. However, this effect may depend on other factors. Thus, predictive models with interaction terms are important for accurately predicting postoperative muscle strength. This study aimed to develop a predictive model for lower muscle strength 12 months after THA which incorporates interaction terms.

Methods

Subjects were female patients with hip osteoarthritis who underwent unilateral THA. Patients with locomotor disorders, neurological disorders, or postoperative complications were excluded. Hip abductor and knee extensor strength were measured, and a generalized linear model approach with preoperative muscle strength, age, body weight, height, disease duration, physical activity, and leg extension as explanatory variables was used to identify factors that determine muscle strength 12 months after THA. Models with interaction terms between preoperative muscle strength and other explanatory variables were also examined.

Results

A total of 82 patients were analyzed. Preoperative muscle strength, age, body weight, physical activity, and disease duration were extracted as factors that significantly and independently determine hip abductor and knee extensor strength. The interaction term between preoperative muscle strength and age was identified as a factor that significantly determines knee extensor strength. Regression coefficients for preoperative knee extensor strength and postoperative muscle strength were significant when age was +1 SD, but not when age was -1 SD.

Conclusions

The predictive model demonstrated that lower muscle strength 12 months after THA is determined by preoperative muscle strength, age, weight, physical activity, disease duration, and preoperative muscle strength, with the effect of preoperative muscle strength on knee extensor strength being dependent on age. When predicting postoperative knee extensor strength using preoperative muscle strength, it is important to consider the effect of age.

Trunk movement compensation identified by inertial measurement units is associated with deficits in physical performance, muscle strength and functional capacity in people with hip osteoarthritis

BACKGROUND

Trunk movement compensation characterized as ipsilateral trunk lean and posterior rotation with respect to pelvis during stance phase of walking is common in people with hip osteoarthritis and a biomarker of deficits in physical function in older adults. However, the relationship between trunk movement compensation on deficits in physical performance, muscle strength and functional capacity is unknown.

METHODS

A cross-sectional study design was used. Two inertial measurement units were used to assess trunk movement compensation during the six-minute-walk-test. Knee extension, knee flexion and hip abduction strength were measured using hand-held dynamometer. Multivariate regression models, controlling for self-reported hip pain, were used to regress trunk movement compensation onto six-minute-walk-test and muscle strength measures. Pairwise t-tests were used to evaluate the difference trunk movement compensation has on functional capacity by comparing the first and last minute of the six-minute-walk-test.

FINDINGS

Thirty-five participants (63.3 ± 7.4 years, 57% male, 28.6 ± 4.5 kg/m²) were enrolled. Greater trunk movement compensation was related to poorer six-minute-walk-test (p = 0.03; r = -0.46). Greater hip abduction weakness was related to increased trunk movement compensation in both the sagittal (p = 0.05; r = -0.44) and frontal (p = 0.04; r = -0.38) planes. Participants demonstrated greater frontal plane trunk movement compensation during the last minute compared to the first minute of the six-minute-walk-test (p < 0.01).

INTERPRETATION

Trunk movement compensation, identified by inertial measure units, is a clinically relevant measure and has a moderate-to-strong relationship on deficits in physical performance, muscle strength and functional capacity. Inertial measurement units can be used as a practical means of measuring movement quality in the clinical setting.

Could the Evaluation of Muscle Strength Imbalances Be Used as a Predictor of Total Hip Arthroplasty?

Loss of muscle strength characterizes the period before total hip arthroplasty (THA). Little is known about whether muscle strength imbalances caused by muscle strength decline could be considered another clinical predictor for THA. This study aimed to determine whether muscle imbalances may be used as a clinical predictor for THA surgery. Thirty-six participants were enrolled in the study. Eighteen patients had THA (THA group), while 18 were healthy elders (CON group). Ipsilateral (H/Q) and bilateral (% Def) muscle imbalances of the knee were assessed. THA patients showed impairment of the extensors on the affected extremity compared to those unaffected. A comparison between the groups proved there were weakened flexors in the THA group on both extremities. A comparison of the imbalances revealed a significant bilateral imbalance of the extensors and ipsilateral imbalance of both extremities in the THA group. We computed two logistic regressions using bilateral and ipsilateral imbalance as the predictors of THA surgery. We found that bilateral extensor imbalance may be used as a predictor for THA (Nagelkerke R² = 0.22). A decrease of the bilateral extensors imbalance by 8% decreases the probability of THA by 8%. The most interesting finding is that the evaluation of the bilateral extensor imbalance may be used as another clinical predictor for THA.

Prevalence and Risk Factors of Falls in Adults 1 Year After Total Hip Arthroplasty for Osteoarthritis: A Cross-Sectional Study

Total hip arthroplasty is very successful in alleviating the pain from osteoarthritis. However, deficits in lower limb strength, gait, and balance after surgery has identified this group at risk of falls. Considering the high number of people annually receiving a total hip arthroplasty, further elaboration of factors associated with falls is needed to refine fall prevention guidelines. The objective was to examine the prevalence and circumstances of falling and the risk factors associated with falling in older adults in the first year after total hip arthroplasty surgery. This was a cross-sectional study involving 108 individuals (age of 72.4 ± 6.5 yrs, 60% females) who had unilateral total hip arthroplasty. The primary outcome was falls and their circumstances during the 12 mos after the total hip arthroplasty. Twenty-five people (23.1%) had at least one fall and most falls (56%) occurred 6-12 mos after surgery. Falls resulted in minor injuries for 44% and 12% reported major injuries. The strongest independent predictor for falls was a history of a previous joint replacement with odds ratio of 7.38 (95% CI = 2.41-22.62, P < 0.001). Overall, the information highlights that falls are common after total hip arthroplasty, yet considering the older age of people having this surgery screening for falls risk should follow established guidelines.

Variation in rehabilitation setting after uncomplicated total knee or hip arthroplasty: a call for evidence-based guidelines

Background

High-level evidence consistently indicates that resource-intensive facility-based rehabilitation does not provide better recovery compared to home programs for uncomplicated knee or hip arthroplasty patients and, therefore, could be reserved for those most impaired. This study aimed to determine if rehabilitation setting aligns with evidence regardless of insurance status.

Methods

Sub-study within a national, prospective study involving 19 Australian high-volume public and private arthroplasty centres. Individuals undergoing primary arthroplasty for osteoarthritis participated. The main outcome was the proportion participating in each rehabilitation setting, obtained via chart review and participant telephone follow-up at 35 and 90 days post-surgery, categorised as ‘facility-based’ (inpatient rehabilitation and/or ≥ four outpatient-based sessions, including day-hospital) or ‘home-based’ (domiciliary, monitored or unmonitored home program only). We compared characteristics of the study cohort and rehabilitation setting by insurance status (public or private) using parametric and non-parametric tests, analysing the knee and hip cohorts separately.

Results

After excluding ineligible participants (bilateral surgeries, self-funded insurance, participation in a concurrent rehabilitation trial, experience of a major acute complication potentially affecting their rehabilitation pathway), 1334 eligible participants remained. Complete data were available for 1302 (97%) [Knee: n = 610, mean age 68.7 (8.5) yr., 51.1% female; Hip: n = 692, mean age 65.5 (10.4) yr., 48.9% female]; 26% (158/610) of knee and 61% (423/692) of hip participants participated predominantly in home-based programs. A greater proportion of public recipients were obese and had greater pre-operative joint impairment, but participated more commonly in home programs [(Knee: 32.9% (79/240) vs 21.4% (79/370) (P = 0.001); Hip: 71.0% (176/248) vs 55.6% (247/444) (P <  0.001)], less commonly in inpatient rehabilitation [Knee: 7.5% (18/240) vs 56.0% (207/370) P (< 0.001); Hip: 4.4% (11/248) vs 33.1% (147/444) (P <  0.001], and had fewer outpatient treatments [Knee: median (IQR) 6 (3) vs 8 (6) (P < 0.001); Hip: 6 (4) vs 8 (6) (P < 0.001)].

Conclusions

Facility-based programs remain the norm for most knee and many hip arthroplasty recipients with insurance status being a major determinant of care. Development and implementation of evidence-based guidelines may help resolve the evidence-practice gap, addressing unwarranted practice variation across the insurance sectors.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2570-8) contains supplementary material, which is available to authorized users.

Postoperative hemoglobin and recovery of hip muscle strength after total hip arthroplasty

Background

The presence/absence of postoperative anemia are presumed to have an impact on early recovery after surgery. This study was performed to compare hip muscle strength and hemoglobin during the perioperative period in 82 patients undergoing THA.

Methods

Evaluation of presence/absence of anemia was performed by calculating the 10-day postoperative/preoperative Hb ratio. Muscle strength was investigated before and 2 months after surgery.

Results

Postoperative SLR strength showed a significant difference between the patients whose 10-day postoperative/preoperative Hb ratio was <85% and ≧ 85%.

Conclusion

We need to consider perioperative strategies to minimize anemia in order to improve patient outcomes.

Early clinical results of total hip arthroplasty assessed with the 25-question Geriatric Locomotive Function Scale and muscle strength testing

BACKGROUND

We think that it is necessary to evaluate whether the patient after total hip arthroplasty has achieved age-appropriate locomotor ability by improvement in hip joint function. The 25-question Geriatric Locomotive Function Scale (GLFS-25) have been determined age-specific standard values for the general population. The aim of this study was to compare postoperative hip muscle strength and functional performance at 3 months after THA with preoperative levels, and to compare the outcomes at 3 months after THA with the function of age-matched adults without hip disease.

METHODS

The GLFS-25 scores and muscle strength were investigated before THA and 3 months after surgery in 12 men and 75 women who underwent total hip arthroplasty.

RESULTS

The mean preoperative and postoperative GLFS-25 score was 55.4 and 19.1, respectively. With regard to the influence of age, the mean scores before and after THA were respectively 52.0 versus 18.2 for patients aged 60-69 years and 61.2 versus 17.3 for those aged 70-79 years in the normal/mild OA group. When female patients from the normal/mild OA group and the implant group classified into levels 4-7 after THA were combined (n = 15), their mean preoperative and postoperative straight leg raising (SLR) strength was 0.56 Nm/kg and 0.75 Nm/kg, respectively. On the other hand, the mean preoperative and postoperative SLR strength was respectively 0.54 Nm/kg and 0.86 Nm/kg for patients classified into levels 1-3 after THA (n = 45).

CONCLUSION

Before THA, 90% of the patients who has severe hip disturbance were in need of nursing care (levels 4-7), while the percentage decreased to 30% after surgery. There was a difference of SLR muscle strength between the patients in levels 4-7 and those in levels 1-3 after THA, suggesting that achieving levels 1-3 postoperatively might depend on whether SLR muscle strength shows improvement.

Comparison of hip muscle volume between fit-and-fill stem and tapered-wedge stem after total hip arthroplasty using the anterolateral approach

BACKGROUND

In total hip arthroplasty (THA) surgery, hip muscle preservation is important in strengthening the stability of the hip and improving the activities of the patient. However, whether the type of femoral stem affects the recovery of the hip muscles remains unknown. The aim of this study was to compare the postoperative hip muscle recovery among femoral stem varieties after THA.

METHODS

The computed tomography (CT) images of 44 patients (44 hips) who underwent THA using an anterolateral approach were reviewed. Twenty-two patients received a fit-and-fill (FF) stem and 22 received the tapered-wedge (TW) stem. The volumes of the gluteus maximus (GMA), gluteus medius (GME), and obturator internus (OI) were measured on three-dimensional models reconstructed using preoperative and 6-month postoperative CT images. Relationships between muscle volume changes and factors including the femoral stem length were evaluated.

RESULTS

The GMA and GME volumes increased postoperatively by 8.2% and 8.3%, respectively, in the FF stem group and 7% and 6%, respectively, in the TW stem group, with no group differences. In contrast, the OI volume decreased postoperatively by 17.8% in the FF group and was preserved in TW group (p < 0.001). Moreover, OI volume was decreased in 19 patients (86%) in the FF group and in 11 patients (50%) in the TW group (p = 0.01). The normalized stem length was significantly associated with the postoperative change in OI volume (r = -0.45, p = 0.002).

CONCLUSIONS

The TW stem showed a significant advantage over the FF stem in terms of OI preservation. Surgeons should pay close attention during surgery to avoid OI injury when using different femoral stem types. We suggest that a short and reduced lateral shoulder femoral stem is a better choice for the preservation of external rotation muscles.

Effects of High- and Low-Velocity Resistance Training on Gait Kinematics and Kinetics in Individuals with Hip Osteoarthritis: A Randomized Controlled Trial

OBJECTIVE

The aim of this study was to investigate the effects of high-velocity (HV) and low-velocity (LV) resistance training on gait kinematics and kinetics in patients with hip osteoarthritis.

DESIGN

This was a single-blind, randomized controlled trial. Forty-six women with hip osteoarthritis were randomly allocated to the HV (n = 23) or LV (n = 23) training group. The participants underwent an 8-week home-based the HV or LV resistance-training program, involving the hip and knee muscles. Outcome measures included gait kinematics and kinetics using 3-dimensional analyses, muscle strength and power, the Harris Hip Score, and hip pain using the visual analog scale.

RESULTS

There was no significant difference in changes for any of the outcome measures between groups. After the training session, muscle power, walking speed, and cadence significantly increased only in the HV group, whereas stride length and the peak hip extension angle during gait significantly increased, and pain on the visual analog scale and the peak ankle dorsiflexion moment during gait significantly decreased only in the LV group. Muscle strength and Harris Hip Score significantly increased in both groups.

CONCLUSIONS

The results of this study may indicate that the potential effect of resistance training on abnormal gait pattern depends on movement velocities during training.