Changes of gluteus medius muscle in the adult patients with unilateral developmental dysplasia of the hip

Efficient musculoskeletal annotation using free-form deformation

Traditionally, constructing training datasets for automatic muscle segmentation from medical images involved skilled operators, leading to high labor costs and limited scalability. To address this issue, we developed a tool that enables efficient annotation by non-experts and assessed its effectiveness for training an automatic segmentation network. Our system allows users to deform a template three-dimensional (3D) anatomical model to fit a target magnetic-resonance image using free-form deformation with independent control points for axial, sagittal, and coronal directions. This method simplifies the annotation process by allowing non-experts to intuitively adjust the model, enabling simultaneous annotation of all muscles in the template. We evaluated the quality of the tool-assisted segmentation performed by non-experts, which achieved a Dice coefficient greater than 0.75 compared to expert segmentation, without significant errors such as mislabeling adjacent muscles or omitting musculature. An automatic segmentation network trained with datasets created using this tool demonstrated performance comparable to or superior to that of networks trained with expert-generated datasets. This innovative tool significantly reduces the time and labor costs associated with dataset creation for automatic muscle segmentation, potentially revolutionizing medical image annotation and accelerating the development of deep learning-based segmentation networks in various clinical applications.

Ultrasonographic screening for developmental dysplasia of the hip: the Graf method revisited

Until the 1980s, the diagnosis of developmental dysplasia of the hip (DDH) was based on clinical examination and radiographic imaging. In 1980, Reinhard Graf developed his own ultrasonographic method for the examination of the infant hip joint. Graf's method evaluates the osseous and cartilaginous coverage of the femoral head by the acetabulum in the infantile hip joint by measuring the angles α and β. The validity of Graf method is that with these measurements the hip joint is further classified by Graf classification into types I to IV that guide treatment. Currently, Graf method is considered the gold standard examination for the diagnosis of DDH in many European countries. This review article aims to discuss the incidence, risk factors and pathophysiology of DDH, and to emphasize on the Graf method for the evaluation, classification, prevention and further management of this entity.

Preoperative Body Composition Correlates with Postoperative Muscle Volume and Degeneration after Total Hip Arthroplasty

Impaired muscle recovery after total hip arthroplasty (THA) may affect gait and activities of daily living. Bioelectrical impedance analysis (BIA) can assess body composition and muscle volume, and computed tomography (CT) can assess muscle volume and the fatty degeneration of muscle. This study aimed to explore the effectiveness of BIA, and the correlation between preoperative body composition and postoperative muscle volume and degeneration after THA using BIA and CT. Thirty-eight patients who underwent THA and had BIA and CT performed pre- and postoperatively were retrospectively assessed. The BIA-derived measurements of preoperative body composition (fat mass index, fat-free mass index, and phase angle) were correlated with the CT-derived measurements (pre- and postoperative muscle volume and gluteus maximus and quadriceps Hounsfield Units of the affected hip). The preoperative fat mass index negatively correlated with the postoperative muscle volume of the gluteus maximus (p = 0.02) and quadriceps (p < 0.001) and the Hounsfield Units of the gluteus maximus (p = 0.03) and quadriceps (p = 0.03). The preoperative fat-free mass index positively correlated with the postoperative muscle volume of the quadriceps (p = 0.02). The preoperative phase angle positively correlated with the postoperative muscle volume of the quadriceps (p = 0.001) and the Hounsfield Units of the gluteus maximus (p = 0.03) and quadriceps (p = 0.001). In patients who underwent THA, preoperative body composition correlated with postoperative muscle volume and the fatty degeneration of the affected lower limb. Preoperative body composition may help predict postoperative muscle volume and fatty degeneration and thus, postoperative recovery.

The effect of experimentally induced gluteal muscle weakness on joint kinematics, reaction forces, and dynamic balance performance during deep bilateral squats

Squatting is a common daily activity and fundamental exercise in resistance training and closed kinetic chain programs. The aim of this study was to investigate the effects of an experimentally induced weakness of the gluteal muscles on joint kinematics, reactions forces (JRFs), and dynamic balance performance during deep bilateral squats in healthy young adults. Ten healthy adults received sequential blocks of (1) branch of the superior gluteal nerve to the tensor fasciae latae (SGNtfl) muscle, (2) superior gluteal nerve (SGN), and (3) inferior gluteal nerve (IGN) on the dominant right leg. At the control condition and following each block, the participants were instructed to perform deep bilateral squats standing on two force plates. Hip, knee, ankle, and pelvis kinematics did not differ significantly following iatrogenic weakness of gluteal muscles. The most important finding was the significant differences in JRFs following SGN and IGN block, with the affected hip, patellofemoral, and ankle joint demonstrating lower JRFs, whereas the contralateral joints demonstrated significantly higher JRFs, especially the patellofemoral joint which demonstrated an average maximum difference of 1.43 x body weight compared with the control condition. When performing a deep bilateral leg squat under SGN and IGN block, the subjects demonstrated an increased center of pressure (CoP) range and standard deviation (SD) in mediolateral compared with the control condition. These results imply that squat performance changes significantly following weakness of gluteal muscles and should be considered when assessing and training athletes or patients with these injuries.

An Analysis of Radiographic Leg Length Discrepancy and Hip Offset in Patients at Risk of Developing Osteoarthritis

Background

Leg length and hip offset are important principles in total hip arthroplasty (THA). Patients may endorse leg length differences (LLD) postoperatively that may be anatomical or functional. The objective of this study was to determine the normal radiographic variation in leg length and hip offset in a preosteoarthritic population without a THA.

Methods

A retrospective study was completed using data from the Osteoarthritis Initiative, a prospective longitudinal study. Patients at risk of developing or with early osteoarthritis without inflammatory arthritis or prior THA were included. Measurements were made from full limb length anterior-posterior (AP) radiographs. Multiple linear regression models were employed to predict side-to-side differences in LLD, Δ femoral offset (FO), Δ abductor muscle length (AML), Δ abductor lever arm, and Δ AP pelvic offset.

Results

The mean radiographic LLD was 4.6 mm, with 12 mm within 1 standard deviation. No significant differences were detected between LLD and sex, age, body mass index, or height. The median radiographic differences in FO, AML, abductor lever arm, and AP pelvic offset were 3.2 mm, 4.8 mm, 3.6 mm, and 3.3 mm, respectively. Height was predictive of Δ FO, while both height and age were predictive of Δ AML.

Conclusions

Radiographic leg length variations in a population without symptomatic or radiographic osteoarthritis exist. FO and AML are dependent on patient characteristics. Preoperative radiographic LLD is not predicted by age, gender, body mass index, or height. It should be stressed that anatomic reconstruction is one of the many goals of arthroplasty and can stand in conflict with the priority and primary goals of stability and fixation, which should be prioritized.

Mechanical upside of PAO mainstream fixations: co-simulation based on early postoperative gait characteristics of DDH patients

Purpose: To investigate the early postoperative gait characteristics of patients who underwent periacetabular osteotomy (PAO) and predict the biomechanical performance of two commonly used PAO fixation methods: iliac screw (IS) and transverse screw (TS). Methods: A total of 12 patients with unilateral developmental dysplasia of the hip (DDH) (mean age 27.81 ± 4.64 years, 42% male) that were scheduled to undergo PAO surgery were included in this study. Their preoperative CT images and pre- and postoperative gait data were used to create subject-specific musculoskeletal models and complete the inverse dynamics analysis (IDA). Two patients with typical gait characteristics were selected using clustering analysis, and their IDA data were incorporated into finite element (FE) models of IS and TS fixations. Failure simulation was performed by applying iterative steps with increasing gait load to predict yield load. Stress results and yield loads were calculated for each FE model at different phases of the gait cycle. Results: Postoperative gait showed improvement compared to preoperative gait but remained inferior to that of healthy individuals. Postoperative gait was characterized by a lower hip range of motion, lower peri-ilium muscle forces, particularly in the abductors, and a sharper initial peak and flatter second peak of hip joint reaction force (HRF). Finite element analysis (FEA) showed a trend of increasing stress during the second-fourth phases of the gait cycle, with lower stress levels in other phases. At high-stress gait phases, the mean stress of maximum p ¯ 100 differed significantly between IS and TS (p < 0.05) and between coupled and uncoupled muscle forces (p < 0.05). Failure analysis predicted a slightly larger yield load for TS configurations (6.21*BW) than that for IS (6.16*BW), but both were well above the gait load. Coupled and uncoupled groups showed similar results, but uncoupled groups had lower yield loads (5.9*BW). Conclusion: PAO early postoperative gait shows a normalized trend, but abnormalities persist. IS and TS are both capable of resisting mechanical strain failure, with no significant mechanical advantage found for transverse screw fixation during PAO early postoperative gait. Additionally, it is important to note that the TS may have a higher risk of cyclic fatigue failure due to the localized greater stress concentration. Furthermore, the most medial screw is crucial for pelvic stability.

Greater hip abductor size in prearthritic patients with developmental dysplasia of the hip versus femoroacetabular impingement

Developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) are common hip pathologies and important risk factors for osteoarthritis, yet the disease mechanisms differ. DDH involves deficient femoral head coverage and a shortened abductor moment arm, so this study hypothesized that the cross-sectional area (CSA) of the gluteus medius/minimus muscle complex and the stabilizing iliocapsularis muscle would be larger in DDH versus FAI, without increased fatty infiltration. A longitudinal cohort identified prearthritic patients with DDH or FAI who underwent imaging before surgery. Patients with DDH and FAI (Cam, Pincer, or Mixed) were 1:1 matched based on age, sex, and body mass index. Magnetic resonance imaging was used to measure the gluteus medius/minimus complex and iliocapsularis in two transverse planes. Amira software was used to quantify muscle and noncontractile tissue. Paired samples t-tests were performed to compare muscle size and composition (p < 0.05). There were no differences in the iliocapsularis muscle. Patients with DDH had significantly larger CSA of the gluteus medius/minimus complex at both transverse planes, and the noncontractile tissue proportion did not differ. The mean difference in overall muscle CSA at the anterior inferior iliac spine was 4.07 ± 7.4 cm² (p = 0.005), with an average difference of 12.1%, and at the femoral head this was 2.40 ± 4.37 cm² (p = 0.004), with an average difference of 20.2%. This study reports a larger CSA of the gluteus medius/minimus muscle complex in DDH compared to FAI, without a difference in noncontractile tissue, indicating increased healthy muscle in DDH.

Artificial intelligence-based volumetric analysis of muscle atrophy and fatty degeneration in patients with hip osteoarthritis and its correlation with health-related quality of life

PURPOSE

Artificial intelligence (AI) technologies have enabled precise three-dimensional analysis of individual muscles on computed tomography (CT) or magnetic resonance images via automatic segmentation. This study aimed to perform three-dimensional assessments of pelvic and thigh muscle atrophy and fatty degeneration in patients with unilateral hip osteoarthritis using CT and to evaluate the correlation with health-related quality of life (HRQoL).

METHODS

The study included one man and 43 women. Six muscle groups were segmented, and the muscle atrophy ratio was calculated volumetrically. The degree of fatty degeneration was defined as the difference between the mean CT values (Hounsfield units [HU]) of the healthy and affected sides. HRQoL was evaluated using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ).

RESULTS

The mean muscle atrophy rate was 16.3%, and the mean degree of muscle fatty degeneration was 7.9 HU. Multivariate correlation analysis revealed that the WOMAC stiffness subscale was significantly related to fatty degeneration of the hamstrings, the WOMAC physical function subscale was significantly related to fatty degeneration of the iliopsoas muscle, and the JHEQ movement subscale was significantly related to fatty degeneration of the hip adductors.

CONCLUSION

We found that fatty degeneration of the hamstrings, iliopsoas, and hip adductor muscles was significantly related to HRQoL in patients with hip osteoarthritis. These findings suggest that these muscles should be targeted during conservative rehabilitation for HOA and perioperative rehabilitation for THA.

Anatomical Parameters Associated with the Shortening Decision in Crowe Type 4 Dysplastic Hip Osteoarthritis: A Case-Control Study

Background

Muscle and bone morphometry may be potent indicators for predicting femoral subtrochanteric shortening osteotomy (FSSO). We aimed to investigate muscular and bony factors that may be predictive of FSSO.

Methods

Patients with unilateral Crowe type 4 developmental dysplasia of the hip (DDH) who underwent unilateral total hip arthroplasty (THA) without (Group 1, 31 patients) and with FSSO (Group 2, 39 patients) were included. Sixty healthy hips (Group 3) were selected as the control group. Several muscular and bony parameters were measured on the operative (O) and non-operative (NO) hips on radiographs and computed tomography (CT) images.

Results

The mean NO gluteus medius cross-sectional area (CSA) index (NO-GMed CI), NO tensor fasia lata (TFL) CI, NO iliopsoas (IP) CI, and NO gluteus maximus (GMax) CI for the control group were lower than those for both Crowe type IV DDH with and without FSSO. The mean NO gluteus minimus CI (NO-GMin CI) for the control group were higher than those for both Crowe type IV DDH with and without FSSO. There was significant difference between Groups 1 and 2 regarding axial position of neo-acetabulum (APNA) (- 0.03 ± 8.5 vs. 5.27 ± 6.33, p = 0.004), coronal position of neo-acetabulum (CPNA) (33.39 ± 10.65 vs. 53.70 ± 12.27, p = 0.000), operative leg length discrepancy (O-LLD) (14.18 ± 15.14 vs. 24.44 ± 15.80, p = 0.001), O-gluteus minimus (GMin) length (155.34 ± 157.73 vs. 106.79 ± 20, p =  < 0.01), and O-GMin CI (57.28 ± 58.59 vs. 29.95 ± 12.13, p =  < 0.01). The cutoff values determined by the receiving operating curve analyses were as follows: 13.7 mm, 2.5 mm, and 41.4 mm for O-LLD, APNA, and CPNA, respectively.

Conclusion

FSSO is associated with APNA, CPNA, O-LLD, O-GMin length, and O-GMin CI. By using cutoff values of APNA, CPNA, and O-LLD, predicting FSSO preoperatively is possible. Owing to these parameters, it may be possible to lower the technically demanding level of surgery.

Prediction of femoral head coverage from articulated statistical shape models of patients with developmental dysplasia of the hip

Developmental dysplasia of the hip (DDH) is commonly described as reduced femoral head coverage due to anterolateral acetabular deficiency. Although reduced coverage is the defining trait of DDH, more subtle and localized anatomic features of the joint are also thought to contribute to symptom development and degeneration. These features are challenging to identify using conventional approaches. Herein, we assessed the morphology of the full femur and hemi-pelvis using an articulated statistical shape model (SSM). The model determined the morphological and pose-based variations associated with DDH in a population of Japanese females and established which of these variations predict coverage. Computed tomography (CT) images of 83 hips from 47 patients were segmented for input into a correspondence-based SSM. The dominant modes of variation in the model initially represented scale and pose. After removal of these factors through individual bone alignment, femoral version and neck-shaft angle, pelvic curvature, and acetabular version dominated the observed variation. Femoral head oblateness and prominence of the acetabular rim and various muscle attachment sites of the femur and hemi-pelvis were found to predict 3D CT-based coverage measurements (R2  = 0.5-0.7 for the full bones, R2  = 0.9 for the joint). Statement of Clinical Significance: Currently, clinical measurements of DDH only consider the morphology of the acetabulum. However, the results of this study demonstrated that variability in femoral head shape and several muscle attachment sites were predictive of femoral head coverage. These morphological differences may provide insight into improved clinical diagnosis and surgical planning based on functional adaptations of patients with DDH.

The biomechanical disadvantage of dysplastic hips

Developmental dysplasia of the hip (DDH) is strongly associated with an increased risk for hip osteoarthritis. Skeletal deformities undeniably contribute to detrimental biomechanical loading in dysplastic hips, but cannot explain all types of damage and symptoms that patients with DDH experience. Characterizing the geometry and function of the muscles spanning the hip is a logical next step in our progression of knowledge about DDH pathomechanics. In this study, we compared skeletal geometry, muscle volumes, intramuscular fatty infiltration, moment arms, and isometric strength in patients with DDH (N = 20) to healthy controls (N = 15). Femoral coverage was significantly less in patients (p < 0.001, Cohen's d effect size = 2.2), femoral neck-shaft angles were larger (p = 0.001, d = 1.3), and hip joint centers (HJCs) were more lateral (p = 0.001, d = 1.3). These skeletal abnormalities were associated with smaller abductor muscle moment arms in patients with DDH (e.g., gluteus medius [GMED]: p = 0.001, d = 1.2). Patients with DDH also had larger GMED volumes (p = 0.02, d = 0.83), but no differences in fatty infiltration, compared to controls. Isometric strength of the hip abductors, extensors, and flexors was lower in patients, but not significantly different from controls. The abnormal skeletal geometry, lateralized HJC, and reduced muscle moment arms represent a chronic biomechanical disadvantage under which patients with DDH operate. This phenomenon causes increased demand on the abductor muscles and results in high medially and superiorly directed joint reaction forces, which can explain reports of superomedial femoral cartilage damage in patients. The abnormal muscle geometry and function, in context with abnormal skeletal structure, are likely strong, but underappreciated, contributors to damaging loads in DDH.

Comparative Analysis of Preoperative and Postoperative Muscle Mass around Hip Joint by Computed Tomography in Patients with Hip Fracture

Purpose

This study was conducted in order to assess changes in hip muscles by comparing results of preoperative and postoperative computed tomography (CT) in older patients who underwent surgery for treatment of hip fracture.

Materials and Methods

A total of 50 patients (aged ≥65 years) who underwent surgery for treatment of intertrochanteric fractures (25 patients) and femoral neck fractures (25 patients) between February 2013 and February 2019 and underwent preoperative and postoperative pelvic CT were enrolled in the study. The cross-sectional area, attenuation and estimates of muscle mass of the gluteus medius, gluteus minimus, iliopsoas, and rectus femoris on the uninjured side were measured. Basic patient data (sex, age, height, weight, body mass index [BMI], bone mineral density [BMD], Harris hip score [HHS], and length of follow-up) were collected from medical records.

Results

No significant differences in sex, age, height, weight, BMI, BMD, HHS, and length of follow-up were observed between the two groups. No significant difference in the cross-sectional areas and attenuations of gluteus medius and gluteus minimus was observed after surgery; however, a statistically significant decrease was observed in those of iliopsoas and rectus femoris after surgery. Lower estimates with statistical significance of muscle mass of the iliopsoas and rectus femoris were observed on postoperative CT.

Conclusion

Muscle mass of the hip flexor (iliopsoas, rectus femoris) showed significant decreases on postoperative CT compared with preoperative CT. Based on these findings, selective strengthening exercise for hip flexor should be beneficial in rehabilitation of hip fractures.

Bilateral Asymmetry in Balance Control During Gait in Children with Treated Unilateral Developmental Dysplasia of the Hip

INTRODUCTION

About 1% of the newborn population has developmental dysplasia of the hip (DDH), altering joint biomechanics, gait performance and balance control. Pemberton's osteotomy is used in early treatment but it remains unclear whether it will help the patient regain normal balance control during gait. The current study aimed to identify the changes of the whole-body balance control during level walking in children treated for unilateral DDH during toddlerhood, in terms of inclination angles (IA) of the line joining the body's center of mass (COM) and center of pressure (COP), and the rate of change of IA (RCIA).

MATERIALS AND METHODS

Twelve girls (DDH group; age: 7.1 ± 2.1 years) who had been treated with Pemberton's osteotomy for unilateral DDH during toddlerhood and twelve healthy controls (Control group; age: 7.6 ± 2.1 years) walked at their preferred walking speed while IA, RCIA and temporal-spatial parameters were calculated from measured kinematic and forceplate data, and were compared using independent t-tests.

RESULTS

Compared to the Control group, the DDH group showed significantly decreased sagittal IA (p = 0.042) but increased range of sagittal RCIA during SLS on the unaffected side (p = 0.006), and increased peak sagittal RCIA during DLS (p < 0.008). In the frontal plane, the altered COM-COP control occurred mainly during stance phase of the affected side, showing a decreased range of RCIA during SLS (p = 0.033) followed by decreased IA (p = 0.045) with an increased peak value of RCIA (p = 0.023) during terminal DLS.

CONCLUSIONS

The children with treated unilateral DDH showed compromised, bilaterally different balance control strategies with altered COM-COP control during gait, not only during stance in the frontal plane as expected, but even more so during swing in the sagittal plane. It is thus suggested that routine assessment of the morphological changes and/or altered balance control of both the unaffected and affected hips is equally important for early identification of any signs of insidious hip problems, deteriorating balance control or increased risk of loss of balance.

Relationship between Perceived Leg Length Discrepancy at One Month and Preoperative Hip Abductor Muscle Elasticity in Patients after Total Hip Arthroplasty

OBJECTIVE

Preoperative factors related to perceived leg length discrepancy (PLLD) after total hip arthroplasty (THA) are not well studied. This study aimed to examine the preoperative factors, including hip abductor modulus, related to PLLD one month after THA.

METHODS

The study included 73 patients diagnosed with osteoarthritis secondary to developmental dysplasia of the hip and a posterior approach to surgery. Multiple logistic regression analysis was performed using the presence or absence of PLLD as the dependent variable and preoperative hip abductor's modulus of elasticity, pain, hip abduction range of motion, hip abductor muscle strength and pelvic obliquity as the independent variable. Additionally, receiver operating characteristic curves were used for the extracted variables for calculating the cutoffs, sensitivity, specificity and area under the curve (AUC) to determine the presence or absence of PLLD. The significance level was set at p<0.05.

RESULTS

The hip abductor modulus (odds ratio=1.13; 95% confidence interval=1.06-1.21; p<0.001) was selected as a preoperative factor. The cutoff value to determine the presence or absence of a PLLD was 16.32 kPa. The sensitivity and specificity were 81.8% and 72.5%, respectively, and the AUC was 0.8137.

CONCLUSION

The hip abductor muscle elastic modulus affected PLLD one month after THA. If the preoperative hip abductor elastic modulus is higher than the cutoff value, it may affect the appearance of PLLD at one month postoperatively.

What happens to the gluteus medius in young and middle-aged patients with hip dysplasia?

BACKGROUND

Much research has focused on quantifying the bony characteristics of patients with developmental dysplasia of the hip (DDH). Far less attention, however, has been paid to muscle abnormalities around the hip such as those in the gluteus medius (GM).

METHODS

We retrospectively examined clinical and imaging data, such as the age of onset and computed tomography (CT) findings, in 108 consecutive hips. Subjects for the control group were selected from our radiology database. Two readers independently evaluated the length (LGM), cross-sectional area (CSA), width (WGM), and thickness (TGM) of the GM and arm of GM (AGM) and angle of the GM activation (AOA) and bony parameters including the acetabulum-head index (AHI), lateral central edge angle (LCEA), acetabular index (AI), femoral offset (FO), and height of the rotation centre of femoral head (HCFH) among all cases using the imaging data.

RESULTS

The patient group included 108 hips. The AGM, LGM, CSA, and TGM were lower in the DDH patients, while AOA was higher. However, there was no significant difference in the WGM between the two groups. Multiple linear regression analysis showed that AGM and AOA were independent factors affecting LCEA. The following regression equation was used: Y(LCEA) = 5.377 * X1 (AGM) - 0.310 * X2 (AOA) - 11.331. The mechanical characteristics of the GM and many bony parameters were significantly correlated (the AGM and AHI, LCEA, AI, FO, but not HCFH; AOA and AHI, LCEA, AI, but not FO or HCFH). The CSA was positively correlated with only HCFH. The rest were not statistical significance linear correlation. The multivariate regression results showed that the age of onset was positively correlated with AGM (r = 0.467). The regression equation used was Y = 9.0 * X (age of onset) - 11.4.

CONCLUSION

We found difference in the morphological and mechanical characteristics of the GM between hips with DDH and hips of normal morphology. Of note, the mechanical characteristics of the GM were influenced by bony parameters in patients with DDH.

Survivorship and functional outcome of a cemented acetabular component with bulk roof autograft for severe acetabular dysplasia: 12- to 23-year follow-up

AIMS

Primary aim was to determine survival of a cemented acetabular component with bulk roof autograft with a minimum of 12 years follow-up. The secondary aim was to determine the clinical outcome.

METHODS

A cohort of 62 consecutive patients (74 hips) undergoing cemented total hip arthroplasty with acetabular bulk roof autograft for acetabular dysplasia were retrospectively identified. The group consisted of 57 female patients (67 hips) and 5 male patients (7 hips) with a mean age at operation of 45 years. No patient was lost to follow-up, however 9 patients died had during the study period. The Oxford Hip Score (OHS), Forgotten Joint Score (FJS), EuroQol 5-Dimensional Score (EQ-5D), Short Form (SF-12) physical score and patient satisfaction were used to assess clinical outcome for patients with a surviving prosthesis.

RESULTS

The median follow-up was 16.6 (13.4-19.1) years. 6 revisions were performed during the follow-up period, all of which were due to aseptic loosening of the acetabular component. The all-cause Kaplan Meier survival rate for the acetabular component was 99% at 10 years, 95% at 15 years and 83% at 20 years. Neither age, gender, femoral osteotomy or polyethylene (UHMW vs. cross-linked) were significant predictors of aseptic revision of the acetabular component. There were no case of graft resorption and all grafts were radiologically incorporated. 45 patients were available for functional assessment at a mean follow-up of 18.2 years. The mean OHS was 37.8, FJS was 55.7, EQ5D was 0.73, and SF-12 physical component was 43.2. No patient was dissatisfied, with 2 patients reporting a neutral satisfaction, 7 stating they were satisfied and the remaining 36 were very satisfied.

CONCLUSIONS

A cemented acetabular component with bulk roof autograft for dysplasia offers excellent survival with good to excellent functional outcome with high patient satisfaction in the medium- to long-term.

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.

Increased Loading Rates During Gait Correlate With Morphology of Unaffected Hip in Juveniles With Treated Developmental Hip Dysplasia

Long-term follow-up studies on children with surgically treated developmental dysplasia of the hip (DDH) have shown that not only the affected side progresses to premature osteoarthritis, but the unaffected side may also suffer from insidious hip dysplasia or osteonecrosis. The current gait analysis study identified the loading and unloading rates of the ground reaction forces (GRF) and lower limb joint axial forces during gait, and their correlations with the hip morphology in twenty juvenile patients with surgically treated unilateral DDH during toddlerhood. In a gait laboratory, each subject walked at preferred speed on a 10-m walkway while the kinematics and the GRF were measured. Loading and unloading rates of the vertical GRF and the joint axial forces were obtained as the maximum instantaneous slope of these force curves. Radiographic measurements of the hips were taken, and the correlations between the morphological parameters and the loading and unloading rates were obtained. The patients showed greater-than-normal peak loading rates of the joint axial forces, and the loading rates on both the affected and unaffected sides were strongly correlated to the acetabular index on the unaffected side, which was also significantly correlated with the peak unloading rates on the affected side. These results suggest that apart from regular follow-up of the affected hip, routine assessment of the morphological changes and/or increased loading rates on the unaffected hip is also important for early identification of any signs of insidious hip dysplasia and risk of premature degeneration of the cartilage.

Volume of Gluteus Maximus and Minimus Increases After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

PURPOSE

To investigate the change in muscle volume around the hip in patients with femoroacetabular impingement (FAI) after arthroscopy and evaluate other factors related to muscle change.

METHODS

We performed a retrospective review of magnetic resonance imaging data of patients with FAI who underwent hip arthroscopy. Magnetic resonance imaging was obtained pre- and postoperatively. The cross-sectional area (CSA) of muscles were determined on axial images. The Wilcoxon signed-rank test was used to determine the differences between pre- and postoperative hip muscle CSA. The correlations of change in muscle CSA with age, sex, body mass index, pain level, preoperative symptom duration, follow-up time, and multiple validated patient-reported outcomes were also analyzed with a Spearman rank correlation test.

RESULTS

Fifty-one patients with a mean age of 36.5 ± 5.6 years were included and analyzed. The follow-up was 26.6 ± 0.5 months (range, 24-40 months), and 27 (52.9%) were women. Patients with FAI showed increased hip muscle CSA of gluteus maximus (P = .002) and gluteus minimus (P = .001). Post- compared with preoperative, the value for the change in medius CSA was underpowered, and no differences in other hip muscle CSAs were observed. The increased muscle CSA of the gluteus maximus was significantly correlated with the improvement of modified Harris Hip Score (ρ = 0.404; P = .003). The increased muscle CSA of the gluteus minimus was significantly correlated with the improvement of pain Visual Analog Scale (ρ = 0.452; P = .001). Age, body mass index, sex, symptom duration, and follow-up time were not significantly correlated with change in muscle CSA.

CONCLUSIONS

Patients with FAI have a significantly increased postoperative muscle CSA of the gluteus maximus (7.8%) and the gluteus minimus (11.6%) compared with preoperative values. The increased muscle CSA of the gluteus maximus and gluteus minimus was significantly correlated with improvement in modified Harris Hip Score and pain Visual Analog Scale, respectively. The increase of muscle volume may be associated with the improvement of subjective function and pain relief.

LEVELS OF EVIDENCE

Level IV, therapeutic case series.

Effects of Hip Abductor Strengthening on Musculoskeletal Loading in Hip Dysplasia Patients after Total Hip Replacement

Hip dysplasia patients after total hip replacement show worse functional performance compared to primary osteoarthritis patients, and unfortunately there is no research on muscle and joint loads that would help understand rehabilitation effects, motor dysfunctions and failure events. We tested the hypothesis that a higher functional improvement in hip dysplasia patients who received hip abductor strengthening after hip replacement, would result in different gait function and musculoskeletal loads during walking compared to patients who performed standard rehabilitation only. In vivo gait analysis and musculoskeletal modeling were used to analyze the differences in gait parameters and hip and muscle forces during walking between the two groups of patients. We found that, in a functional scenario of very mild abnormalities, the patients who performed muscle strengthening expressed a more physiological force pattern and a generally greater force in the operated limb, although statistically significant in limited portions of the gait cycle, and likely related to a higher gait speed. We conclude that in a low-demand task, the abductor strengthening program does not have a marked effect on hip loads, and further studies on hip dysplasia patients would help clarify the effect of muscle strengthening on loads.

Evaluation of muscle volume and degeneration after total hip arthroplasty: a comparison of the posterolateral approach and the anterolateral supine approach

Background

Muscle strength around the hip after total hip arthroplasty (THA) is crucial for preventing dislocation and limping. This study aimed to assess and compare muscle volume and degeneration after THA using the posterolateral (PL) and anterolateral (AL) approaches.

Methods

Sixty-four hips in 64 patients who underwent primary THA were retrospectively analyzed. Patients were segregated into the PL group (35 hips) and AL group (29 hips) for evaluating pre- and postoperative muscle volumes and degeneration around the hip. Computed tomography (CT) examinations were performed preoperatively and 6 months post THA. The muscle volume and Hounsfield units (HU) of the gluteus maximus (G-max), gluteus medius (G-med), tensor fasciae latae, internal obturator muscle, and external obturator muscle were measured.

Results

In the PL group, the postoperative muscle volume of the G-max significantly increased than the preoperative muscle volume. In contrast, the postoperative muscle volume of the internal obturator muscle was significantly lower than the preoperative muscle volume. The postoperative HU of the internal and external obturator muscles were significantly lower than the preoperative HU. In the AL group, the postoperative muscle volumes of the G-max, G-med, and tensor fasciae latae significantly increased than their preoperative muscle volumes. The postoperative HU of the G-med and tensor fasciae latae were significantly higher than the preoperative HU values.

Conclusion

The PL approach can lead to degeneration of the internal and external obturator. The AL approach is more beneficial for recovering the G-med, tensor fasciae latae, and internal obturator muscle than the PL approach.

Abductor muscle strengthening in THA patients operated with minimally-invasive anterolateral approach for developmental hip dysplasia

OBJECTIVE

In developmental hip dysplasia (DDH) patients, the chronic dislocation of the femoral head with respect to the true acetabulum determines muscle contracture and atrophy, particularly of the abductor muscles, and leads to secondary osteoarthritis (OA) with severe motor dysfunction, pain and disability. The correct positioning when a total hip replacement (THR) is performed is fundamental to the recovery of gait function. Also, inadequate rehabilitation of the abductor muscles for pelvic stabilisation can be responsible for residual dysfunction. Consensus on a programme for abductor muscle strengthening in these patients is not currently available. The aim of this study was to evaluate the effectiveness of a specific program of exercises for strengthening the abductor muscles in these patients.

METHODS

A multicentre, prospective, randomised clinical trial was carried out in an outpatient rehabilitation setting on 103 patients given THR for DDH through a minimally-invasive anterolateral approach. Patients were randomly divided into a Study Group, including 46 patients, and a Control Group, including 57 patients. All patients underwent standard early postoperative rehabilitation. In addition, the Study Group were given an extra 2-week rehabilitation once full weight-bearing on the operated limb was allowed, aimed at strengthening the abductor muscles. All patients were evaluated preoperatively, and at about 3 and 6 months postoperatively. Clinical measures (lower limb-length differences, hip range of motion, abductor muscle strength), and functional measures (WOMAC, HHS, 10mt WT, SF-12) were taken.

RESULTS

Hip range of motion and functional outcome measures showed a progressive improvement at follow ups in both groups, significantly higher in the Study Group. In particular, abductor strength at 6 months post-op improved by 92.5% with respect to 35.7% in the Control Group.

CONCLUSION

In addition to standard rehabilitation, a rehabilitation programme for strengthening the gluteal muscles in DDH patients who underwent THR determined an increase in muscle strength that improved functional performance and patient satisfaction.

Dysplastic hip anatomy alters muscle moment arm lengths, lines of action, and contributions to joint reaction forces during gait

Developmental dysplasia of the hip (DDH) is characterized by abnormal bony anatomy, which causes detrimental hip joint loading and leads to secondary osteoarthritis. Hip joint loading depends, in part, on muscle-induced joint reaction forces (JRFs), and therefore, is influenced by hip muscle moment arm lengths (MALs) and lines of action (LoAs). The current study used subject-specific musculoskeletal models and in-vivo motion analysis to quantify the effects of DDH bony anatomy on dynamic muscle MALs, LoAs, and their contributions to JRF peaks during early (~17%) and late-stance (~52%) of gait. Compared to healthy hips (N = 15, 16-39 y/o), the abductor muscles in patients with untreated DDH (N = 15, 16-39 y/o) had smaller abduction MALs (e.g. anterior gluteus medius, 35.3 vs. 41.6 mm in early stance, 45.4 vs. 52.6 mm late stance, p ≤ 0.01) and more medially-directed LoAs. Abduction-adduction and rotation MALs also differed for major hip flexors such as rectus femoris and iliacus. The altered MALs in DDH corresponded to higher hip abductor forces, medial JRFs (1.26 vs. 0.87 × BW early stance, p = 0.03), and resultant JRFs (5.71 vs. 4.97 × BW late stance, p = 0.05). DDH anatomy not only affected hip muscle force generation in the primary plane of function, but also their out-of-plane mechanics, which collectively elevated JRFs. Overall, hip muscle MALs and their contributions to JRFs were significantly altered by DDH bony anatomy. Therefore, to better understand the mechanisms of joint degeneration and improve the efficacy of treatments for DDH, the dynamic anatomy-force relationships and multi-planar functions of the whole hip musculature must be collectively considered.

Risk of Dislocation After Total Hip Arthroplasty in Patients with Crowe Type IV Developmental Dysplasia of the Hip

Objective

To investigate whether the risk of dislocation after total hip arthroplasty (THA) in patients with Crowe type IV developmental dysplasia of the hip (DDH) is high and to further identify the risk factors for postoperative dislocation in these patients.

Methods

This retrospective cohort study reviewed Crowe type IV DDH patients undergoing THA between January 2009 and December 2017 in our institution. Each Crowe type IV DDH patient was matched with three Crowe type I, II, or III DDH patients according to gender, side and date of operation. The primary outcome of this study was postoperative dislocation after THA. Occurrence, rate, classification, treatment and outcome of dislocation were documented in detail for all patients. The dislocation rates were compared between Crowe type IV DDH patients and Crowe type I, II, or III DDH patients. Demographic data, implant factors, and surgical factors were compared between the dislocation and no dislocation groups. Multiple logistic regression analysis was used to determine the independent risk factors for dislocation in Crowe type IV hips.

Results

A total of 131 Crowe type IV hips were followed up for a mean of 76.5 ± 28.1 months. Three hundred and ninety‐three Crowe type I, II and III hips, including 261 type I hips, 94 type II hips, and 38 type III hips, were identified as controls and followed up for a mean of 76.4 ± 28.2 months. No significant difference was observed in follow‐up time between two groups (P = 0.804). One or more dislocations occurred in 22 of the 524 dysplasia hips (4.20%). Of the 22 dislocated hips, 20 hips (90.9%) were successfully managed with non‐operative treatment. Two patients (9.1%, one Crowe type I and one Crowe type IV) experienced recurrent dislocation and required revision surgery. Crowe type IV hips had a significantly higher postoperative dislocation rate than type I, II, and III hips (11.45% vs 1.78%, P < 0.001). The use of a 22‐mm femoral head (odds ratio [OR] = 23.55, 95% confidence interval [CI] = 1.901–291.788, P = 0.014), older age (OR = 1.128, 95% CI = 1.037–1.275, P = 0.031), and absence of false acetabulum (OR = 12.425, 95% CI = 1.982–77.879, P = 0.007) were identified as independent risk factors for dislocation in Crowe type IV hips.

Conclusions

Crowe type IV DDH patients were at a high risk of dislocation after THA, and using large femoral heads and improving abductor muscle strength may help decrease the rate of postoperative dislocation in such patients.

Treatment of Osteoarthritis Secondary to Developmental Dysplasia of the Hip with Prolotherapy Injection versus a Supervised Progressive Exercise Control

BACKGROUND Osteoarthritis secondary to developmental dysplasia of the hip (DDH) is one of the major causes of hip pain and disability. The aim of the study was to compare the effectiveness of prolotherapy (PrT) injections versus exercise protocol for the treatment of DDH. MATERIAL AND METHODS There were 46 hips of 41 patients who had osteoarthritis secondary to DDH included in this study. Patients were divided into 2 groups: treated with PrT (PrT group; n=20) and exercise (control group; n=21). Clinical outcomes were evaluated with visual analog scale for pain (VAS) and Harris hip score (HHS) at baseline, 3 weeks, 3 months, 6 months, and a minimum of 1-year follow-up. In PrT group clinical results were also compared in Crowe type I-IV hips. RESULTS Between group analysis revealed no significant between group differences at baseline. Dextrose injection recipients out performed exercise controls for VAS pain change score at 6 months (-4.6±2.6 versus -2.8±2.5; P=0.016), and 12 months (-4.5±2.4 versus -2.9±2.5; P=0.017) and for HHS at 6 months (24.2±14.0 versus 14.8±12.4; P=0.007) and 12 months (24.3±13.4 versus 16.5±11.3; P=0.018). CONCLUSIONS To our best knowledge, this study is the first regarding the effects of an injection method in the treatment of osteoarthritis secondary to DDH. According to our study, PrT is superior to exercises. PrT could provide significant improvement for clinical outcomes in DDH and might delay surgery.

Patients With Unilateral Femoroacetabular Impingement Syndrome Have Asymmetrical Hip Muscle Cross-Sectional Area and Compensatory Muscle Changes Associated With Preoperative Pain Level

PURPOSE

To compare the symptomatic hip muscle cross-sectional area (CSA) in patients with unilateral femoroacetabular impingement syndrome (FAIS) with the asymptomatic-side hip muscle CSA and to determine whether correlations exist between the hip muscle CSA and preoperative pain level, preoperative symptom duration, and postoperative function.

METHODS

We performed a retrospective review of magnetic resonance imaging data of patients who underwent hip arthroscopy from January 2012 through June 2015 for the treatment of unilateral FAIS and who had a minimum of 2 years' follow-up after hip arthroscopy for FAIS. A picture archiving and communication system workstation with an embedded region-of-interest tool was used to measure the muscle CSA of both the symptomatic and asymptomatic sides in FAIS patients. One-way repeated-measures analyses of variance were used to determine differences between symptomatic and asymptomatic hip muscle CSAs. Spearman rank correlations were used to determine relations between the symptomatic-side hip muscle CSA and preoperative pain level, preoperative symptom duration, and multiple validated patient-reported outcomes to quantify the level of function.

RESULTS

A total of 50 patients met the inclusion criteria and were analyzed. The mean age of the patients was 34.22 ± 14.12 years, and 64% were women. Specific muscles of the symptomatic hip displaying significantly decreased CSAs compared with the asymptomatic hip included the gluteus maximus (P = .007), gluteus minimus (P = .022), and rectus femoris (P = .028). The tensor fascia lata (ρ = 0.358; P = .011), pectineus (ρ = 0.369, P = .008), adductor longus (ρ = 0.286, P = .044), and obturator externus (ρ = 0.339, P = .016) showed a moderate positive correlation with preoperative pain level on a visual analog scale in unilateral FAIS patients. No associations were found between the symptomatic-side hip muscle CSA in patients with unilateral FAIS and symptom duration or patient-reported function.

CONCLUSIONS

Patients with unilateral FAIS have a significantly decreased muscle CSA in the symptomatic hip compared with the asymptomatic hip. The symptomatic-side hip muscle CSA was correlated with the preoperative pain level on a visual analog scale. The association between the muscle CSA and preoperative pain level may represent a compensatory change in muscle function around the hip joint in patients with unilateral FAIS.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Effect of exercise therapy combined with branched-chain amino acid supplementation on muscle strengthening in persons with osteoarthritis

Background

Improving lower limb muscle strength is important in preventing progression of osteoarthritis (OA) and its symptoms. Exercise with branched-chain amino acid (BCAA) supplementation has been reported to affect protein anabolism in young and elderly persons. However, few studies provided daily BCAAs for patients with OA.

Objective

This study examined the effects of combined BCAAs and exercise therapy on physical function improvement in women with hip OA scheduled for total hip arthroplasty.

Methods

The subjects were 43 women with OA (age: 64.2 ± 9.4). The participants were randomly divided into two groups: BCAA ( n = 21 ) and control ( n = 22 ). The combined therapy was carried out for one month. Exercise intervention involved hip abductor muscle exercise in both groups. For the nutritional intervention, 6 g of BCAAs or 1.2 g of starch were consumed within 10 min before starting the exercise.

Results

There was a marginally significant difference in the main effect between the groups in 10-m timed gait time. The improvement rate in hip abductor muscle strength of the contralateral side was significantly greater in the BCAA group.

Conclusion

By combining BCAA intake and exercise therapy, a significant improvement in hip abductor muscle strength of the contralateral side was achieved in women with OA.

Advanced Concepts in Hip Morphology, Associated Pathologies, and Specific Rehabilitation for Athletic Hip Injuries

Hip and groin injuries comprise up to 17% of athletic injuries and can pose rehabilitation challenges for many athletes. Injuries involving abnormal femoral acetabular morphology, reduced range of motion, and decreased lumbopelvic strength and endurance also may increase the risk of injury to lower extremities and delay return to play if proper rehabilitation does not take place. The rehabilitation of athletic hip injuries requires a multifaceted interdisciplinary approach that manages the interplay of multiple factors to restore preinjury function and facilitate return to play. Emphasis should be placed on activity modification, preservation of the arcs of range of motion, functional strengthening of the lumbopelvic core, and optimization of proprioceptive and neuromechanical strategies. Communication between providers and the injured athlete also is crucial to ensure that proper therapeutic approaches are being applied.

Decreased postoperative gluteus medius muscle cross-sectional area measured by computed tomography scan in patients with intertrochanteric fractures nailing

BACKGROUND

In patients with femoral intertrochanteric fractures treated by cephalomedullary (CM) nailing, abduction force reportedly decreased by 25-30% during the postoperative follow-up period. The purpose of the current study is to evaluate the cross-sectional area (CSA) and adipose tissue ratio (ATR) of the gluteus medius muscle on the postoperative computed tomography (CT) view, expecting this graphic study will support clinical results.

MATERIALS AND METHODS

A total of 27 patients with femoral intertrochanteric fractures treated by CM femoral nail implants completed the study. The mean age at osteosynthesis was 83 years (range: 72-94 years). The mean postoperative follow-up period was 23 months. The three CT axial slice views were defined as slices A, B, and C corresponding to proximal, midway, and distal part of gluteus medius, respectively. The CSA and ATR were assessed bilaterally.

RESULTS

The mean and standard deviation of CSA values (mm²) between the nonoperated/ operated side were as follows: slice A: 2225.8 ± 621.2/1984.5 ± 425.8; slice B: 2145.1 ± 538.3/1854.9 ± 383.9; and slice C: 1711.0 ± 459.0/1434.5 ± 396.9 ( p < 0.01 in slices A, B, and C). The mean and standard deviation of ATR values (%) from the nonoperative/ operative side were as follows: slice A: 2.8 ± 1.7/5.2 ± 3.5; slice B: 2.7 ± 1.9/4.6 ± 3.2; and slice C: 3.6 ± 3.0/4.8 ± 3.2 ( p < 0.01 in slices A and B and p < 0.05 in slice C).

CONCLUSION

Our image findings documented that gluteus medius is significantly changed in CSA and ATR. The damage possibly triggers decrease in muscular strength of hip abduction in the postoperative follow-up period. This measurement is objective, and needed no patient's endurance and cooperation.

Hip Abductor Muscle Volume and Strength Differences Between Women With Chronic Hip Joint Pain and Asymptomatic Controls

Study Design Secondary analysis, cross-sectional study. Background Chronic hip joint pain (CHJP) can lead to limitations in activity participation, but the musculoskeletal factors associated with the condition are relatively unknown. Understanding the factors associated with CHJP may help develop rehabilitation strategies to improve quality of life of individuals with long-term hip pain. Objectives To compare measures of hip abductor muscle volume and hip abductor muscle strength between women with CHJP and asymptomatic controls. Methods Thirty women, 15 with CHJP and 15 matched asymptomatic controls (age range, 18-40 years), participated in this study. Magnetic resonance imaging was used to determine the volume of the primary hip abductor muscles, consisting of the gluteus medius, gluteus minimus, a small portion of the gluteus maximus, and the tensor fascia latae, within a defined region of interest. Break tests were performed using a handheld dynamometer to assess hip abductor strength. During the strength test, the participant was positioned in sidelying with the involved hip in 15° of abduction. Independent-samples t tests were used to compare muscle volume and strength values between those with CHJP and asymptomatic controls. Results Compared to asymptomatic controls, women with CHJP demonstrated significantly increased gluteal muscle volume (228 ± 40 cm³ versus 199 ± 29 cm³, P = .032), but decreased hip abductor strength (74.6 ± 16.8 Nm versus 93.6 ± 20.2 Nm, P = .009). There were no significant differences in tensor fascia lata muscle volume between the 2 groups (P = .640). Conclusion Women with CHJP appear to have larger gluteal muscle volume, but decreased hip abductor strength, compared to asymptomatic controls. J Orthop Sports Phys Ther 2017;47(12):923-930. Epub 9 Oct 2017. doi:10.2519/jospt.2017.7380.

CT-based analysis of muscle volume and degeneration of gluteus medius in patients with unilateral hip osteoarthritis

Background

The gluteus medius (GMED) affects hip function as an abductor. We evaluated muscle volume and degeneration of the GMED by using CT-based analysis and assessed factors that affect hip abductor strength in patients with unilateral hip osteoarthritis (OA).

Methods

We examined clinical and imaging findings associated with hip abductor strength in consecutive 50 patients with unilateral hip OA. Hip abductor muscle strength and Harris hip score (HHS) were assessed. Leg length discrepancy (LLD) and femoral offset were assessed using X-ray; CT assessment was employed for volumetric and qualitative GMED analysis. Volumetric analysis involved measurement of cross sectional area (CSA) and three-dimensional (3D) muscle volume. CT density was measured for the qualitative assessment of GMED degeneration with or without adjustment using a bone mineral reference phantom.

Results

Hip abductor muscle strength on the affected side was significantly lower than that on the contralateral healthy side and positively correlated with overall score and score for limping of gait of HHS, demonstrating the importance of hip abductor strength for normal hip function. A significant correlation was found between CSA and 3D muscle volume, unadjusted CT density and adjusted CT density, and hip abductor strength and these CT measurements. Multiple linear regression analysis demonstrated that 3D muscle volume, adjusted CT density, and LLD are independent factors affecting hip abduction.

Conclusions

3D measurement of muscle volume and adjusted CT density more accurately reflect quantity and the GMED quality than do conventional assessments. Increase in muscle volume, recovery of muscle degeneration, and correction of LLD are important for improving limping in patients with hip OA.

The radiological research for pelvis asymmetry of unilateral developmental dysplasia of the hip in adult

Objectives

To investigate whether adult patients with unilateral developmental dysplasia of the hip (UDDH) have pelvic asymmetry and what correlation existing between them.

Methods

A total of 100 adult patients with UDDH were enrolled in the retrospective observational study in Shanghai Jiaotong University Affiliated Sixth People’s Hospital, Shanghai, China, between January 2012 and February 2014. The anteroposterior pelvic radiographs were reviewed and the pelvic heights and ischium heights were measured and compared between the affected and non-affected sides to find out the relationship between the pelvic morphology and hip dysplasia.

Results

The pelvic heights demonstrated significant differences between the non-affected side and the affected side in patients with Crowe type II-IV UDDH (p<0.05), but not in patients with Crowe type I UDDH (p=0.09). There were significant differences in the bilateral ischium heights in patients with Crowe type III and IV UDDH (p<0.05), but not in patients with Crowe type I and II UDDH (p=0.78, p=0.055). In addition, the degree of hip dysplasia was positively associated with the degrees of asymmetry of pelvis (r=0.78, p<0.001) and ischium (r=0.72, p<0.001) in UDDH patients.

Conclusion

The pelvic asymmetry exists in adult patients with UDDH. In addition, the degree of asymmetry has correlation with the degree of hip dysplasia. We recommend that it should be taken more cautions to use teardrops and ischial tuberosity as anatomy landmarks to balance leg-length discrepancy for unilateral DDH patients in preoperative planning and total hip arthroplasty.

Effects of perioperative factors and hip geometry on hip abductor muscle strength during the first 6 months after anterolateral total hip arthroplasty

[Purpose] The importance and effect of hip joint geometry on hip abductor muscle strength are well known. In addition, other perioperative factors are also known to affect hip abductor muscle strength. This study examined the relative importance of factors affecting hip abductor muscle strength after total hip arthroplasty. [Subjects and Methods] The subjects were 97 females with osteoarthritis scheduled for primary unilateral THA. The following variables were assessed preoperatively and 2 and 6 months after surgery: isometric hip abductor strength, radiographic analysis (Crowe class, postoperative femoral offset (FO)), Frenchay Activities Index, compliance rate with home exercise, Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ), and demographic data. Factors related to isometric hip abductor muscle strength 2 and 6 months after surgery were examined. [Results] Significant factors related to isometric hip abductor muscle strength at 2 and 6 months after surgery were, in extraction order: 1. isometric hip abductor muscle strength in the preoperative period; 2. BMI; and 3. the JHEQ mental score at 2 and 6 months after surgery. [Conclusion] Preoperative factors and postoperative mental status were related to postoperative isometric hip abductor strength. FO was not extracted as a significant factor related to postoperative isomeric hip abductor strength.

Small femoral offset is a risk factor for lateral femoral cutaneous nerve injury during total hip arthroplasty using a direct anterior approach

INTRODUCTION

Lateral femoral cutaneous nerve (LFCN) injury is a risk specific to the direct anterior approach (DAA) for total hip arthroplasty (THA). However, prevention strategies have not been established. This study aimed to identify the predisposing factors determining LFCN injury during THA via a DAA.

HYPOTHESIS

Patients with LFCN injury after THA via DAA would demonstrate predisposing factors.

MATERIAL AND METHODS

LFCN injury was identified using a patient questionnaire. Potential factors predisposing to LFCN injury were identified in four categories in patient records: patient factors (age, sex, BMI, diagnosis and range of hip motion), surgical factors (surgical time and surgeon's experience of the DAA), preoperative radiographic factors (neck-shaft angle, femoral offset, acetabular offset, total offset and length of muscle on computed tomography axial image) and radiographic changes (differences between each offset pre- and post-surgery). Multivariate analysis was performed to identify risk factors for LFCN injury during this surgery.

RESULTS

After application of inclusion and exclusion criteria, 102 hips (28 with LFCN injury; 74 without) in 102 patients (17 males, 85 females; mean age 66.0 years [range, 26-88 years]) were included. Univariate analysis of patients with and without LFCN injury revealed that small preoperative femoral offset and short preoperative long axis of the tensor fascia lata were statistically significant risk factors for LFCN injury (P=0.004, and P=0.01, respectively). Multivariate analysis showed that small preoperative femoral offset was the only independent risk factor for LFCN injury (odds ratio, 0.895; 95% Confidence Interval, 0.817-0.981; P=0.0018).

DISCUSSION

Smaller femoral offset was a significant risk factor for LFCN injury following THA via a DAA. Our recommendations are that careful attention should be paid to the skin-fascia incision and subcutaneous exposure, and that excessive retraction of the sartorius muscle and tensor fascia lata should be avoided, to reduce the risk of LFCN injury in patients with a small femoral offset.

LEVEL OF EVIDENCE

IV, retrospective historical cohort study.

Cementless Total Hip Replacement for the Management of Severe Developmental Dysplasia of the Hip in the Middle Eastern Population: A Prospective Analysis

Introduction

In the Middle East, severe developmental dysplasia of the hip with subsequent high dislocation is often seen. We assessed the efficiency of total hip replacement (THR) with subtrochanteric shortening femoral osteotomy and trochanteric advancement in this population.

Methods

This prospective study assessed 25 female patients with symptomatic and severe (Crowe IV). Pre- and postoperative Harris hip score (HHS) and Oxford hip score (OHS) were performed alongside assessment of leg length discrepancy (LLD) and the ability to sit in a cross-legged position.

Results

The mean HHS and OHS improved pre-operatively at 1 and 10 years, respectively (p-value < 0.001). The mean postoperative LLD was 3 mm (0–8 mm). Functionally, 22/25 patients were able to sit cross-legged. None of the 25 hips underwent revision during this period.

Conclusion

Total hip replacement with subtrochanteric shortening osteotomy in combination with trochanteric advancement is sufficient for the management of Crowe type IV hips in this population.

Volume Increases of the Gluteus Maximus, Gluteus Medius, and Thigh Muscles After Hip Arthroplasty

BACKGROUND

Muscle atrophy in osteoarthritis (OA) patients is expected to recover after total hip arthroplasty (THA) because of the increase in activity levels. Although some reports have shown an increase in the thigh muscles (Th) after THA, no reports of increases in the gluteal muscles and of analyses of the factors related to muscle recovery have been published. In this study, the changes in the gluteal and Th volumes after THA were quantitatively evaluated using computed tomography (CT) images, and the factors related to muscle recovery were analyzed.

METHODS

The subjects were 40 OA hips with CT images taken 3 weeks after THA (first postoperative [postop] CT) and more than 2 years after THA (second postop CT). The cross-sectional areas of gluteus maximus (G-max), gluteus medius (G-med), and Th were measured in both CT images. The factors related to muscle recovery that were measured and evaluated were age, gender, days from operation, surgical approach, Kellgren-Lawrence grades, and hip functional score (Japanese Orthopaedics Association hip score).

RESULTS

All measured cross-sectional areas of the operated side increased significantly from the first postop CT to the second postop CT (G-max, 40%; G-med, 11%; and Th, 20%). In the analysis of the factors related to muscle recovery, the increase rate of G-max correlated significantly with patient age, and the increase rate of G-med correlated significantly with the increase in Japanese Orthopaedics Association hip score.

CONCLUSIONS

Hip OA can lead to atrophy of the gluteal and Th, but the muscle volume can recover more than 2 years after THA.

Sciatic nerve course in adult patients with unilateral developmental dysplasia of the hip: implications for hip surgery

Background

Sciatic nerve injury is a disastrous adverse complication of surgery and can cause debilitating pain, functional impairment and poor quality of life. Patients with developmental dysplasia of the hip (DDH) have a high incidence of sciatic nerve injury after total hip arthroplasty (THA). A better understanding of the course of the sciatic nerve in patients with DDH may help minimise the risk of sciatic nerve injury after THA.

Methods

A total of 35 adult patients with unilateral DDH were enrolled in this retrospective study. We reviewed the patients’ computed tomography (CT) scans, which included the area from the iliac crest to below the lesser trochanter. The distance between the sciatic nerve and regional anatomic landmarks in four different sections on CT scans was measured to identify the course of the sciatic nerve.

Results

The distance from the sciatic nerve to the spine’s midline was shorter on the affected side than on the healthy side (p < 0.05); the same difference was also detected in the distance to the ilium/ischium outside the true pelvis (p < 0.05). The distance to the greater trochanter was longer on the affected side (p < 0.05). However, the two sides showed no significant difference in the distance from the sciatic nerve to the lesser trochanter (p > 0.05).

Conclusions

For patients with unilateral DDH, the sciatic nerve was located near the ischium and ilium but relatively far from the femur of the affected hip joint, compared to its location on the healthy side. These findings reveal that sciatic nerve becomes shorter in the affected low-limb and is relatively unlikely to be directly injuried using the posterolateral approach in patients with unilateral DDH.

Partial greater trochanter osteotomy for hip reduction in total hip arthroplasty for high dislocated hip: a preliminary report

Background

Hip reduction in total hip arthroplasty for high dislocated hips is difficult. Various femur osteotomy procedures have been used for hip reduction, but these methods increase operative time and risk of nonunion. We investigated the efficacy of a novel partial greater trochanter osteotomy technique for hip reduction in total hip arthroplasty for patients with high hip dislocation.

Methods

Twenty-one patients (23 hips) with high dislocated hip were treated with total hip arthroplasty that included partial greater trochanter osteotomy, i.e., the upper 2/3 greater trochanter was resected, and the gluteus medius muscle attachment was spared. The clinical outcome was evaluated by comparing the Harris hip scores and radiographic exam results, obtained before surgery and at follow-ups.

Results

Follow-ups of 21 patients ranged from 13 to 56 months. The mean Harris hip score increased from preoperative 55.0 (36–69) to postoperative 86.1 (71–93; P = 0.00). The average preoperative leg length discrepancy in patients with unilateral high hip dislocation was 46 mm (28–65 mm); postoperatively leg length discrepancy was less than 1 cm in 11 patients, between 1 and 2 cm in 8 patients, and more than 2 cm in 2 patients. The average leg lengthening at the time of surgery was 36 mm (24–54 mm). Trendelenburg’s gait changed from positive to negative in 20 hips by the last follow-up. No nerve injury occurred postoperative.

Conclusion

Partial greater trochanter osteotomy is an effective method to render hip reduction in total hip arthroplasty for patients with high dislocation of the hip.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-293) contains supplementary material, which is available to authorized users.

Impact of osteoid osteomas of the hip on the size and fatty infiltration of the thigh muscles

We aimed to assess the impact of osteoid osteomas of the hip on the size and fatty infiltration of the muscle thigh in 42 patients. The thigh circumference, cross-sectional areas, and fatty atrophy of four anterior muscles were assessed on magnetic resonance axial T1-weighted images. A significant fatty atrophy was found in the studied muscles of the ipsilateral thigh except for the rectus femoris. No significant association was demonstrated with pain duration suggesting that muscle atrophy may rather be related to the locoregional inflammation than subsequent to the disuse of the limb.

Effect of preoperative limb-length discrepancy on abductor strength after total hip arthroplasty in patients with developmental dysplasia of the hip

BACKGROUND

Limb-length discrepancy (LLD) arising from hip subluxation or dislocation and accompanied by insufficiency of hip abductor in patients with developmental dysplasia of the hip (DDH) can be corrected partially or completely with total hip arthroplasty (THA). However, information about post-THA changes in abductor strength related to preoperative LLD in patients with DDH is lacking. We aimed to explore the post-THA recovery course of abductor muscle strength and its related factors in patients with DDH.

METHODS

A cohort of 45 patients with unilateral DDH was divided into two groups according to their Crowe classification: patients with class I or II DDH formed Group M, and patients in class III and IV DDH formed Group S. The following parameters were measured on standardized antero-posterior hip radiographs taken in the supine position pre- and post-THA: abductor muscle length, abductor lever arm, LLD, and femoral offset (FO). Abductor strength was evaluated quantitatively with the Isomed 2000 isokinetic test system (1 week before the operation and 1, 3, 6, and 12 months after the operation). The contralateral normal hip joint served as a within-patient control. The affected side:healthy side ratios of the parameters above were calculated.

RESULTS

Abductor strength ratio evaluated at the five follow-up time points was larger in Group M than that in Group S (p < 0.001). The average abductor strength ratio reached 78.5, 85.4, and 89.2% at the 3, 6, and 12 months postoperative exams, respectively, in Group M, and reached 50.3, 63.2, and 72.9% in Group S. The abductor muscle length ratio, the abductor muscle level arm ratio, and the FO ratio were significantly increased postoperatively, relative to preoperative assessment, in the two groups. LLD was reduced significantly postoperatively, relative to preoperative values, in both groups. Both preoperative LLD (r = -0.791, p < 0.001) and the change in abductor muscle length ratio (r = -0.659, p < 0.001) correlated with abductor strength recovery.

CONCLUSION

Patients showed the greatest improvement in abductor strength within the first 6 months after THA, especially during the first 3 months. Abductor strength was consistently greater in patients with mild dysplasia than in patients with severe dysplasia. The extent of preoperative LLD and the increase in abductor length were related with post-THA abductor strength recovery in patients with DDH.

The ratio of femoral head diameter to pelvic height in the normal hips of a Chinese population

OBJECTIVE

The aim of this study was to determine whether the ratio between the femoral head diameter and pelvic height in a Chinese population is the same as that found in Westerners.

MATERIALS AND METHODS

Standard pelvic radiography was performed on a group of 187 Chinese adult subjects consisting of 81 males and 106 females with a mean age of 40 years (21-68 years). Femoral head diameter (vertical distance from the femoral head-neck junction to the highest point of the femoral head) and pelvic height (vertical distance from the highest point of the iliac crest to the edge of the ischial tuberosities) were measured.

RESULTS

There were significant differences between males and females (p < 0.001), and between persons of high height versus low height (p = 0.011) and medium height (p = 0.039). There were no significant differences between persons of different age (p = 0.244), body mass index (p = 0.091), or between persons of low- and medium-height groups (p = 0.69). The overall mean ratio between the femoral head diameter and pelvic height was 0.215 (0.173-0.249) with a 95 % CI = 0.214-0.217. The mean ratios in males and females were 0.221 (0.194-0.249) and 0.211 (0.173-0.238), respectively.

CONCLUSION

The mean ratio in Chinese population was similar to the reported ratio in a western population (about 1:5). We suggest that Chinese surgeons may be able to use the Crowe classification to classify patients with hip dysplasia.