Acetabular dysplasia and hip osteoarthritis in Britain and Japan

Volume and quality of the gluteal muscles are associated with early physical function after total hip arthroplasty

PURPOSE

Identifying muscles linked to postoperative physical function can guide protocols to enhance early recovery following total hip arthroplasty (THA). This study aimed to evaluate the association of preoperative pelvic and thigh muscle volume and quality with early physical function after THA in patients with unilateral hip osteoarthritis (HOA).

METHODS

Preoperative Computed tomography (CT) images of 61 patients (eight males and 53 females) with HOA were analyzed. Six muscle groups were segmented from CT images, and muscle volume and quality were calculated on the healthy and affected sides. Muscle quality was quantified using the mean CT values (Hounsfield units [HU]). Early postoperative physical function was evaluated using the Timed Up & Go test (TUG) at three weeks after THA. The effect of preoperative muscle volume and quality of both sides on early postoperative physical function was assessed.

RESULTS

On the healthy and affected sides, mean muscle mass was 9.7 cm3/kg and 8.1 cm3/kg, and mean muscle HU values were 46.0 HU and 39.1 HU, respectively. Significant differences in muscle volume and quality were observed between the affected and healthy sides. On analyzing the function of various muscle groups, the TUG score showed a significant association with the gluteus maximum volume and the gluteus medius/minimus quality on the affected side.

CONCLUSION

Patients with HOA showed significant muscle atrophy and fatty degeneration in the affected pelvic and thigh regions. The gluteus maximum volume and gluteus medius/minimus quality were associated with early postoperative physical function. Preoperative rehabilitation targeting the gluteal muscles on the affected side could potentially enhance recovery of physical function in the early postoperative period.

Gait Characteristics of Fallers and Nonfallers in Female Patients with Unilateral End-Stage Hip Osteoarthritis

BACKGROUND/OBJECTIVES

Osteoarthritis of the hip (hip OA) may increase the risk of falls. To decrease fall risk, it is important to assess the gait characteristics of patients with hip OA in detail. This study aimed to investigate the gait characteristics of patients with hip OA caused by falls by simultaneously assessing foot and waist trajectories via an inertial measurement unit (IMU).

METHODS

The subjects were 77 patients with hip OA, 17 of whom had fallen in the past year. The physical function, gait parameters, and waist trajectories of the fall and nonfall groups were compared.

RESULTS

Compared with the nonfall group, the fall group was older and had higher fall scores and lower Japan Orthopaedic Association (JOA) hip scores. With respect to gait characteristics, the stride length on the nonaffected side was significantly shorter in the fall group than in the nonfall group. Stride velocity gait asymmetry was also significantly lower in the fall group than in the nonfall group. The amount of lifting of the waist on the affected and nonaffected sides was significantly lower in the falling group than in the nonfalling group.

CONCLUSIONS

It was suggested that the fall group might be adapting to stabilization and adjusting to a stable and safe gait pattern because of the effects of falls; new gait characteristics regarding falls in patients with hip OA were found.

Deficient postoperative anterior wall index adversely affects joint survival after transposition osteotomy of the acetabulum in patients with hip dysplasia

Aims

This study aimed to determine clinical outcomes; relationships between postoperative anterior, lateral, and posterior acetabular coverage and joint survival; and prognostic factors for joint survival after transposition osteotomy of the acetabulum (TOA).

Methods

Data from 616 patients (800 hips) with hip dysplasia who underwent TOA between November 1998 and December 2019 were reviewed. The median follow-up period was 8.9 years (IQR 5 to 14). A medical notes review was conducted to collect demographic data, complications, and modified Harris Hip Score (mHHS). Radiological indicators of acetabular coverage included lateral centre-edge angle (LCEA), anterior wall index (AWI), and posterior wall index (PWI). The cumulative probability of TOA failure (progression to Tönnis grade 3 or conversion to total hip arthroplasty) was estimated using the Kaplan-Meier product-limited method. A multivariate Cox proportional hazards model was used to identify predictors for failure.

Results

Median mHHS improved from 68 preoperatively to 96 at the latest follow-up (p < 0.001). The overall joint survival rate was 97% at ten years and 70% at 20 years. For the postoperative LCEA subgroups, survival in the deficient group was lower than that in the excessive (p = 0.006) and normal (p = 0.007) groups. For the postoperative AWI subgroups, survival in the deficient group was lower than that in the excessive (p = 0.015) and normal (p < 0.001) groups. Multivariate analysis identified age (p = 0.010), Tönnis grade 2 (p < 0.001), roundness index (p = 0.003), fair joint congruity (p = 0.004), and postoperative AWI (p = 0.002) as independent risk factors.

Conclusion

Deficient postoperative AWI adversely affected joint survival after TOA, underscoring the importance of sufficient anterior acetabular coverage, along with precise surgical indications, to ensure successful hip joint preservation in the treatment of hip dysplasia.

Morphometric Assessment of the Hip Joint in a Functional Dysplastic Rabbit Model

The present study investigates the morphometric changes in the hip joint in a surgically induced rabbit model of hip dysplasia through the sectioning of the ligamentum capitis femoris and pelvic limb immobilization. A total of seventeen rabbits were evaluated using radiographic and computed tomographic imaging to measure the following parameters: the femoral angles of anteversion and inclination, length and width indexes of the neck of the femur, and acetabular depth and ventroversion. Significant differences in femoral anteversion angle and acetabular depth were observed, particularly in the group of hip instability surgery with pelvic limb immobilization. The results have shown the influence of hip joint instability in the promotion of femoral anteversion and acetabular shallowing. These findings provide a foundation for future research on naturally occurring or experimentally induced hip dysplasia in rabbits and underscore the model's potential for studying the biomechanical and developmental aspects of hip joint disorders.

Bone morphology and physical characteristics of the pro-cyclist hip joint

PURPOSE

This study aimed to investigate the radiographic findings for the hip joint and hip range of motion in professional cyclists, and to determine their bone morphology and physical characteristics. The effects of physical characteristics on athletic performance were examined in terms of metabolic efficiency using simulation analysis.

METHODS

We performed a case-control research study on 22 hips in 11 male professional cyclists (average age 28.5, height 1.73 m, weight 77.6 kg). Thirty hips in 15 healthy male volunteers were selected as controls. As radiographic evaluations, acetabular dysplasia was assessed on standardized radiographs. During physical evaluations, the hip range of motion was examined. We used simulation analysis to investigate the metabolic efficiency in the different cycling forms.

RESULTS

The radiographic evaluations showed a significant difference in the incidence of acetabular dysplasia (p = 0.01): 59% (13/22 hips) in the pro-cyclist group versus 10% (3/30 hips) in the control group. The physical evaluations revealed significant differences in the hip internal rotation angle (p = 0.01), with greater ranges of internal rotation in the pro-cyclist group versus the control group. The simulation analyses showed that metabolism was reduced in the cycling form with hip internal rotation, especially in the lower extremities.

CONCLUSIONS

Pro-cyclists showed a high frequency of acetabular dysplasia and superior hip internal rotation. According to the cycling model analyses, hip internal rotation allowed pedaling with reduced metabolic power.

Life Course Epidemiology of Hip Osteoarthritis in Japan: A Multicenter, Cross-Sectional Study

BACKGROUND

The incidence of developmental dysplasia of the hip (DDH) in Japanese newborns has reduced drastically following a primary prevention campaign initiated around 1972 to 1973; this perinatal education campaign promoted maintaining the hips of newborns in the naturally flexed-leg position. The purpose of the present study was to describe the life course epidemiology of hip osteoarthritis (OA) in adolescent and adult patients and to assess its association with exposure to the primary prevention campaign for DDH.

METHODS

We included new patients with hip OA diagnosed from January 1, 2022, to December 31, 2022, at 12 core hospitals (8 special-function hospitals and 4 regional medical care support hospitals). The trend in the percentage of hips with a history of DDH treatment in childhood was estimated with use of a centered moving average using the birth year of the patient. We compared the prevalence of severe subluxation (Crowe type II, III, or IV) between patients with secondary hip OA due to hip dysplasia who were born in or before 1972 and those who were born in or after 1973.

RESULTS

Overall, 1,095 patients (1,381 hips) were included. The mean age at the time of the survey was 63.5 years (range, 15 to 95 years). A total of 795 patients (1,019 hips; 73.8% of hips) were diagnosed with secondary OA due to hip dysplasia. Approximately 13% to 15% of hips among patients born from 1963 to 1972 had a history of DDH treatment in childhood; however, the percentage decreased among patients born in or after 1973. The prevalence of severe subluxation (Crowe type II, III, or IV) among patients born in or after 1973 was 2.4%, which was significantly less than that among patients born in or before 1972 (11.1%; odds ratio, 0.20; p < 0.001).

CONCLUSIONS

As of 2022, secondary hip OA due to hip dysplasia is still responsible for most new cases of adolescent and adult hip OA seen in core hospitals in Japan. However, the perinatal education campaign initiated 50 years ago, which utilized a population approach and advocated for maintaining the hips of newborns in the naturally flexed-leg position, may have improved the environmental factors of DDH, as indicated by the apparently reduced need for treatment of DDH in childhood and the associated severe subluxation. This may result in a reduced need for challenging hip surgery later in life.

LEVEL OF EVIDENCE

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

Morphological features of the acetabulum with coxa profunda in women: a retrospective observational study

BACKGROUND

The morphology of coxa profunda remains inadequately understood. However, knowledge about the characteristics of the acetabulum in coxa profunda can help to predict pelvic morphology in three dimensions based on radiographic findings, as well as help to diagnose and predict hip pathologies. Therefore, this study aimed to investigate the relationship between the morphological characteristics of the pelvis and coxa profunda.

METHODS

We conducted a retrospective analysis including women who had undergone unilateral total hip arthroplasty. Only those with normal hip joint morphology on the opposite side, as evidenced by anteroposterior pelvic radiography showing a distance of ≥ 2 mm between the ilioischial line and acetabular floor, were included. Five parameters related to acetabular anteversion, thickness, and the position of the ilioischial line were measured using axial computed tomography at the central hip joint. The coxa profunda group (n = 39) and control group (n = 34) were compared.

RESULTS

The mean acetabular anteversion angle was 12.5° ± 4° in the control group and 22.3° ± 5.6° in the coxa profunda group. The mean thickness from the acetabular fossa to the medial wall was 7.5 ± 1.7 mm in the control group and 3.9 ± 1.2 mm in the coxa profunda group. Furthermore, the bony region representing the ilioischial line was positioned more posteriorly in the coxa profunda group than it was in the control group.

CONCLUSION

Our findings suggest that coxa profunda in women is associated with anterior acetabular dysplasia and a thin acetabulum, in contrast to previous interpretations of excessive coverage. This insight suggests a conversion of coxa profunda from a finding of pincer-type femoroacetabular impingement to a finding of acetabular dysplasia, a revelation that also draws attention to cup positioning for total hip arthroplasty.

The Three-Dimensional Criteria of Developmental Dysplasia of the Hip Using the Functional Pelvic Plane Is More Useful Than That Using the Anterior Pelvic Plane

Background: This retrospective cross-sectional study investigated the cutoff values (COVs) for developmental dysplasia of the hip (DDH) using a three-dimensional (3D) pelvic model reconstructed using computed tomography (CT). We included 107 healthy Japanese participants and 73 patients who had undergone curved periacetabular osteotomy (CPO) for DDH between 2012 and 2017. Methods: The hip CT images were adjusted to the anterior pelvic plane (APP), functional pelvic plane (FPP), sagittal anterior center-edge angle (ACEA), and sagittal posterior center-edge angle (PCEA). The lateral center-edge angle (LCEA), acetabular roof obliquity (ARO), anterior acetabular sector angle (AASA), and posterior acetabular sector angle (PASA) were measured. Receiver operating characteristic (ROC) curves were used to calculate the COVs, and the association between the parameters was analyzed using multiple logistic regression. Results: The ARO (≥10.2°) and LCEA (≤22.2°) were independent influencing factors for the APP, whereas the AASA (≤53.1°) and LCEA (≤24.5°) were independent influencing factors for the FPP. Conclusions: The 3D criteria for the diagnosis of DDH in Japanese individuals can identify DDH with insufficient anterior coverage, which anteroposterior plain radiographs cannot visualize, and can help determine indications for acetabular osteotomy.

Novel subtype of coxitis knee associated with acetabular dysplasia of the hip: a case series

BACKGROUND

Multiple joint arthritis patterns require a comprehensive understanding to optimize patient management. This study aimed to present a patient cohort that deviated from known definitions of coxitis knee (CK), identifying and characterizing this atypical group.

METHODS

Patients undergoing both total hip arthroplasty and total knee arthroplasty between January 2008 and December 2018 were retrospectively reviewed. The patients were classified into a typical coxitis knee group (classic, long leg arthropathy, and windswept deformity) and an atypical coxitis knee group. Leg-length discrepancy, body mass index (BMI), and radiographic parameters of the groups were compared and analyzed.

RESULTS

A total of 31 patients were allocated to the typical coxitis knee group (n = 10), and atypical coxitis knee group (n = 21). In the atypical group, 27 hips were involved, of which 21 had acetabular dysplasia, 5 exhibited subchondral insufficiency fracture-like changes, and only 1 had classic osteoarthritis. Among the 27 knees undergoing total knee arthroplasty, 26 showed varus alignment, 1 was within the normal range, and none was valgus. Acetabular dysplasia involved ipsilateral (n = 1), contralateral (n = 14), and bilateral (n = 6) hips, showing atypical coxitis knee. Patients with acetabular dysplasia were more likely to exhibit atypical CK.

CONCLUSION

Most patients in the cohort displayed acetabular dysplasia and contralateral varus knees, constituting a pattern referred to as acetabular dysplasia-associated gonarthritis. Identifying this novel subtype may have important clinical implications for regions with high risk factors, where acetabular dysplasia and constitutional genu varum are prevalent.

Association Between Anterior Hip Capsule Thickening and Sagittal Pelvic Alignment Among Patients With Developmental Dysplasia of the Hip

INTRODUCTION

The pathogenesis and pathology of secondary osteoarthritis (OA) of the hip, which is mainly due to developmental dysplasia of the hip (DDH), in Japan are obscure. There are some reports on the thickening of the hip capsule, but the relationship between the thickness of the hip capsule and the pelvic alignment due to hip deformity is not well known. This research investigated whether the capsular thickness of female DDH patients was related to pelvic alignment.

METHODS

This single-center cross-sectional study included female patients aged 50-79 years (n=13) who had undergone primary total hip arthroplasty (THA) due to secondary hip OA with a background of DDH. The part of the hip capsule including the iliofemoral ligament was resected and measured directly with a digital caliper. The Sharp angle, center-edge (CE) angle, sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), and lumbar lordosis angle (LLA) were measured with an X-ray image to investigate the relationship between the capsular thickness and the pelvic posture.

RESULTS

Pearson's correlation coefficient showed a negative correlation between hip capsular thickness and Sharp angle (r=-0.57, p>0.05). No significant correlation was found between the thickness of the hip capsule and the sagittal X-ray parameters including SS, PT, PI, LLA, and CE angle in the coronal plane.

CONCLUSION

The thickness of the hip capsule is moderately associated with the Sharp angle on the coronal plane. The results of this study suggest that the thickness of the joint capsule does not necessarily relate to the degenerative process among patients with DDH and the process can be complex to apply two-dimensional postural indices for the explanation.

Hip Pain and Movement Dysfunction Associated With Nonarthritic Hip Joint Pain: A Revision

The Academy of Orthopaedic Physical Therapy (AOPT), formerly the Orthopaedic Section of the American Physical Therapy Association (APTA), has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). This is an update to the 2014 Clinical Practice Guideline (CPG) for Hip Pain and Movement Dysfunction Associated with Nonarthritic Hip Joint Pain. The goals of the revision were to provide a concise summary of the contemporary evidence since publication of the original guideline and to develop new recommendations or revise previously published recommendations to support evidence-based practice. This current CPG covers pathoanatomical features, clinical course, prognosis, diagnosis, examination, and physical therapy interventions in the management of nonarthritic hip joint pain. J Orthop Sports Phys Ther 2023;53(7):CPG1-CPG70. doi:10.2519/jospt.2023.0302.

Evaluation of lateral and anterior center-edge angles according to sex and anterior pelvic plane tilt angle: a three-dimensional quantitative analysis

BACKGROUND

This study aimed to quantitatively evaluate lateral center-edge angle (LCEA) and anterior center-edge angle (ACEA) according to sex and the anterior pelvic plane (APP) tilt angle and analyze the correlation between these measurements and acetabular coverage.

METHODS

Computed tomography scans of 71 adults (38 men and 33 women) with normal hip joints were obtained. LCEA, anterior ACEA, and acetabular coverage were measured with APP tilt every 5° from - 30° to + 30° and were compared between the sexes. The correlation between acetabular coverage and LCEA/ACEA was also analyzed.

RESULTS

(1) LCEA, ACEA, and acetabular coverage were statistically larger in men than in women at all APP tilt angles (with the exception of acetabular coverage ≥ 25°). (2) LCEA, ACEA, and acetabular coverage differed according to APP tilt angle. LCEA and acetabular coverage showed maximum values at 10°. ACEA showed a tendency to increase by an average of 3.6° for every 5° increase in the APP tilt angle. LCEA demonstrated strong and very strong associations across all APP tilting angles, whereas ACEA showed a moderate association at angles ≥ 15° in men and ≥ 30° in women.

CONCLUSIONS

The LCEA and ACEA are adequate measurement methods that reflect actual acetabular coverage unless the pelvis is tilted excessively anteriorly. While pelvic tilting does not need to be considered for LCEA within the physiologic range, it should always be taken into account for ACEA, as it increases by an average of 3.6° for every 5° increase in APP tilt angle.

LEVEL OF EVIDENCE

Level III: retrospective cohort study.

Standard radiographic values for the acetabulum in Japanese adolescents: a cross-sectional study

BACKGROUND

Most previous reports of normal acetabular radiographic values focused on adults or elderly people. Recent reports have described premature hip osteoarthritis in adolescents not caused by acetabular dysplasia. In addition, there is a certain failure rate of surgical treatment for young patients with borderline acetabular dysplasia. Accurate indices for treatment of adolescent hips are unclear because standard measurement values of the adolescent acetabulum have not been reported.

METHODS

This cross-sectional study involved 552 Japanese adolescents aged 12-18 years who had scoliosis or suspected scoliosis and asymptomatic hips. All persons underwent plain standing anteroposterior whole-spine radiography, and measurements were obtained using the pelvic part of the radiograph. We excluded persons who were unable to correctly perform measurements because of conditions such as pelvic rotation or lateral inclination and persons in whom closure of the triradiate cartilage or closure of the secondary ossification centers of the acetabulum had not yet occurred. In 1101 hips, we measured the lateral center-edge angle (LCEA), Tönnis angle, Sharp angle, acetabular head index (AHI), lateral subluxation (LS), vertical subluxation (VS), and peak-to-edge distance (PED). We evaluated the correlation coefficient and coefficient of determination between each parameter and age, height, body weight, and body mass index (BMI) and assessed the intra- and inter-rater reliability of each radiographic parameter.

RESULTS

Among all hips, the mean of each parameter was as follows: LCEA, 27.9° ± 4.8°; Tönnis angle, 5.0° ± 3.7°; Sharp angle, 44.1° ± 3.1°; AHI, 82.1% ± 5.5%; LS, 5.4 ± 1.4 mm; VS, 0.3 ± 1.2 mm; and PED, 14.0 ± 2.3 mm. The correlation between each parameter and age, height, body weight, and BMI was considerably low. Intra- and inter-rater reliability was moderate or good for almost all parameters.

CONCLUSIONS

The values for each radiographic parameter of the acetabulum in this study are considered standard for the adolescent acetabulum without age-related changes. Some parameters differ slightly from the normal values for adults or elderly people in previous reports; thus, we suggest careful evaluation of these parameters for adolescents.

The prevalence of hip osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

To estimate the global prevalence of hip osteoarthritis (HOA) through a systematic review and meta-analysis, and to determine by regression analysis the respective relationships between age and sex, and sex and prevalence.

METHODS

EMBASE, PubMed, Web of science, CINAHL, and SCOPUS were searched from inception until August 2022. Two authors independently extracted data and assessed the quality of the retrieved literature. Random-effects meta-analysis was performed to derive the pooled prevalence. Variations in the prevalence estimate in different subgroups, including diagnostic methods, region, and patient sex, were examined by subgroup meta-analysis. Meta-regression was used to construct the age-specific prevalence of HOA.

RESULTS

A total of 31 studies were included in our analysis, involving 326,463 participants. Quality evaluation showed that all studies included in the analysis had a Quality Score of at least 4. The most frequently used method for diagnosing HOA was the Kellgren-Lawrence (K-L) grade classification, accounting for 19/31 (61.3%) studies. The pooled prevalence of HOA diagnosed based on the K-L grade ≥ 2 criterion was 8.55% (95% CI 4.85-13.18) worldwide. The prevalence of HOA was lowest in Africa at 1.20% (95% CI: 0.40-2.38), followed by Asia at 4.26% (95% CI 0.02-14.93) and North America at 7.95% (95% CI 1.98-17.36), and highest in Europe at 12.59% (95% CI 7.17-19.25). There was no statistically significant difference in HOA prevalence between men (9.42%, 95% CI:4.81-15.34) and women at (7.94%, 95% CI: 3.57-13.81). The regression model showed a correlation between age and the prevalence of HOA.

CONCLUSION

HOA has high prevalence worldwide and increases with age. The prevalence varies significantly by region but not by patient sex. High-quality epidemiological studies are warranted to more accurately estimate the prevalence of HOA.

Genome-Wide Association Study and Transcriptome of Japanese Patients with Developmental Dysplasia of the Hip Demonstrates an Association with the Ferroptosis Signaling Pathway

This study examined the association between developmental dysplasia of the hip (DDH) and disease-associated loci in a Japanese cohort. A genome-wide association study (GWAS) of 238 Japanese patients with DDH and 2044 healthy individuals was performed. As a replicate, GWAS was also conducted on the UK Biobank data with 3315 cases and matched 74,038 controls. Gene set enrichment analyses (GSEAs) of both the genetics and transcriptome of DDH were performed. Transcriptome analysis of cartilage specimens from DDH-associated osteoarthritis and femoral neck fractures was performed as a control. Most of the lead variants were very low-frequency ones in the UK, and variants in the Japanese GWAS could not be replicated with the UK GWAS. We assigned DDH-related candidate variants to 42 and 81 genes from the Japanese and UK GWASs, respectively, using functional mapping and annotation. GSEA of gene ontology, disease ontology, and canonical pathways identified the most enriched pathway to be the ferroptosis signaling pathway, both in the Japanese gene set as well as the Japanese and UK merged set. Transcriptome GSEA also identified significant downregulation of genes in the ferroptosis signaling pathway. Thus, the ferroptosis signaling pathway may be associated with the pathogenic mechanism of DDH.

Radiographic markers of hip dysplasia in young adults: predictive effect of factors in early life

ABSTRAC

BACKGROUND AND OBJECTIVES: Acetabular dysplasia in young adults occurs, despite screening for developmental hip dysplasia (DDH) in the neonatal period. We aimed to examine how early life factors predict radiographic measurements of acetabular dysplasia at 18-19 years of age.

METHODS

From a previous randomized trial (n = 12,014; 1988-90) evaluating the role of hip ultrasound in newborn screening of DDH, 4469 participants (2193 males) were invited to a follow-up 18 years later (2007-09), of which 2370 (53% attendance; 932 males) met. We examined associations between early life factors and four radiographic measurements for acetabular dysplasia at skeletal maturity. Hierarchical regressions, with addition of variables observed/measured consecutively in time, were analyzed using mixed effects models considering hip as the unit in the analyses. The study is approved by the Regional Ethics Committee.

RESULTS

In total, 2340 participants (921 boys), mean age 18.7 years, (SD 0.6) had hip radiographs performed at follow-up and were included. Early life factors significantly predicting radiographic acetabular dysplasia at age 18-19-years included female gender, breech, low acetabular inclination (alpha) angle and sonographic instability, abduction treatment, as well as the velocity of growth during childhood. A positive family history of DDH was not associated with acetabular dysplasia at skeletal maturity.

CONCLUSION

The acetabular inclination (alpha) angle as measured on ultrasound at birth turned out to be a significant predictor of dysplasia at 18-19 years of age. The discordant role of a positive family history in early versus adult hip dysplasia is intriguing, warranting further studies on the genetic mechanisms of DDH.

Effects of Walking With a Cane on Frontal Plane Hip Joint Loading in Patients With Late-Stage Unilateral Hip Osteoarthritis

Objective

To investigate the effects of walking with a cane on frontal plain bilateral hip joint loading in patients with late-stage unilateral hip osteoarthritis (OA).

Design

Nonrandomized experimental design.

Setting

Urban inpatient hospital.

Participants

Adults (men, n=10; women, n=17) with osteoarthritis who were scheduled for total hip arthroplasty (N=27).

Intervention

Gait with and without a T-cane was assessed using a 3-dimensional motion analysis system.

Main Outcome Measures

Peak hip adduction moment and hip adduction moment impulse, vertical ground reaction force, and ground reaction force impulse were assessed under 4 different conditions: OA side vs non-OA side with non-cane gait, OA side vs non-OA side with cane gait, non-cane vs cane gait on OA side, and non-cane vs cane gait on non-OA side. The lateral trunk lean angle in the stance phase on both sides was compared between with and without a cane. Pain during walking with and without a cane was also determined using a visual analog scale (0=no pain; 100=most painful).

Results

Walking with a cane reduced the peak hip adduction moment from an average of 0.76 to 0.57 Nm/kg (reduction approximately 25%) and the mean hip adduction moment impulse from 50.58 to 42.78 Nm/kg (reduction approximately 15%) on the affected side. Walking with a cane reduced the peak ground reaction force from an average of 10.15 to 9.20 N/kg but did not markedly affect the mean ground reaction force impulse on the affected side. The mean impulse of vertical ground force and hip adduction moment on the nonaffected side with a T-cane was larger than that without a cane (940.4 vs 899.2, 73.7 vs 68.8, respectively), albeit without statistical significance. The mean lateral trunk lean angle on the affected side was 5.85±3.95 degrees with a non-cane gait and 4.46±2.66 degrees with a T-cane gait, showing a significant difference. Furthermore, walking with a cane was associated with a significant decrease in the visual analog scale of pain from 42.1 to 26.4.

Conclusion

These findings indicate that walking with a cane reduces the load and pain on the affected hip joint. The effect of the cane on the trunk lean was small, but it is worth noting that walking with a cane may increase the load on the healthy side.

Three-dimensional foot trajectory in female patients with end-stage hip osteoarthritis during walking

Osteoarthritis (OA) is a risk factor for falls. To decrease the fall risk, it is important to evaluate the detailed features of the gait of patients with OA. This study aimed to investigate the spatio-temporal parameters of gait in patients with end-stage hip OA, especially foot trajectory. We measured normal speed gait in patients with hip OA and in healthy controls (HCs) using inertial measurement units attached to shanks. The stride lengths in the affected and unaffected sides in the patients with hip OA were shorter than those in the HCs, but the position of maximum foot clearance was not significantly different between the two groups. The patients with hip OA compensated the position of maximum foot clearance to avoid fall risk. The horizontal plane foot trajectory in patients with hip OA suggests that the lateral bending of the trunk during walking, which is frequently seen in them, was a result of the lateral distance at swing down being located significantly more medially on the unaffected side than on the affected side. Herein, a new gait parameter of lateral distance at swing was discovered by a detailed evaluation of three-dimensional foot trajectory of female patients with end-stage hip OA.

The influence of calcar collar and surface finish in the cemented femoral component on the incidence of postoperative periprosthetic femoral fracture at a minimum of five years after primary total hip arthroplasty

INTRODUCTION

Cemented femoral component design including its mechanical behavior in total hip arthroplasty (THA) has influenced the occurrence of postoperative periprosthetic femoral fracture (PPFF). The main aim of this study was to investigate the influence of the calcar collar and surface finish in the cemented femoral component on the risk of PPFF.

MATERIALS AND METHODS

This retrospective review was undertaken of 1082 primary THAs in 912 patients using cemented femoral components followed for a minimum of five years (mean, 9.4 years; range, 5-24 years). The incidence of PPFF, patients' demographics and surgical details were evaluated. Kaplan-Meier survivorship analysis was performed for four different outcomes: any PPFF, revision of the femoral component for PPFF, aseptic loosening, and for any reason.

RESULTS

The overall incidence of PPFFs was 1.0% (n = 11): 1.4% (n = 10) in the collarless polished (CLP) group, none in the collared polished (CP) group and 0.6% (n = 1) in the collared non-polished (CNP) group (p > 0.05). Kaplan-Meier survival analysis for the femoral component at 12 years with PPFF as the end point was 97.4% (95% confidence interval [CI], 94.9 to 99.8) in the collarless group and 99.7% (95% CI, 99.1 to 100) in the collared group (p = 0.048). With revision of the femoral component for aseptic loosening as the end point, survivorship was 100.0% in the CLP and CP groups, and 98.1% (95% CI, 95.9 to 100) in the CNP group (CLP vs CP, p > 0.999; CLP vs CNP, p = 0.001; CP vs CNP, p = 0.112).

CONCLUSION

This study demonstrated that the calcar collar in the cemented femoral component could play an important role to reduce the incidence of PPFF. The surface finish in the cemented femoral components influenced the incidence of femoral component revision for aseptic loosening over 5-12 years. Surgeons should consider not only the geometry and the mechanical function of the femoral components based on different design philosophies, but also potential complications associated with different designs that may require revision arthroplasty.

Prevalence of radiographic hip dysplasia in Japanese population-based study

OBJECTIVES

The purpose of this study was to measure the indices of radiographic developmental dysplasia of the hip (DDH) in a cross-sectional study of an elderly Japanese population.

METHODS

Hip radiographs of 427 informed, voluntary Japanese community-dwelling individuals (279 female and 148 male) aged 50-96 years-old were obtained from Miyagawa village in Japan through a health screening. The hip radiographs were measured by a custom-written, semi-automated MATLAB program. The center edge (CE) angle, acetabular roof obliquity (ARO), acetabular head index (AHI), and minimum joint space width (mJSW) were measured. We examined the associations between gender, side-of-hip, and age group on radiographic DDH and hip osteoarthritis (OA).

RESULTS

The mean CE angle was 31.0°. The mean ARO was 5.8°. The mean AHI was 88.2%. The mean mJSW was 4.0 mm. Of the total population, 29.9% had DDH and 4.0% had hip OA. Of those who had hip OA, 41.2% were secondary OA, and 58.8% were primary OA. The relationship between DDH and OA was not significant.

CONCLUSION

DDH is unlikely to be an important cause of hip OA in the present population-based study.

Factors affecting spine–femur discordance in the percentage of young adult mean on dual-energy X-ray absorptiometry in the elderly population: a retrospective study

Background

Several retrospective studies have reported spine–femur discordance in bone mineral density (BMD) values. However, the average age of individuals in these studies was the mid-50s, which is younger than the typical age of individuals requiring treatment for primary osteoporosis. Therefore, we aimed to investigate factors associated with discordance in the percentage of young adult mean (YAM) between the lumbar spine and femoral neck in the elderly population.

Methods

We evaluated 4549 dual-energy X-ray absorptiometry (DXA) measurements obtained from 2161 patients (269 men and 1892 women) between January 2014 and December 2017 at our hospital. For individuals with more than one eligible set of measurements, the first record was used. We investigated each patient’s age, sex, body mass index, current smoking status, alcohol consumption, use of steroids, presence of diabetes mellitus, and presence of rheumatoid arthritis.

Results

The mean age of the patients was 76.4 ± 8.9 years. Older age (p <  0.001), male sex (p <  0.001), and diabetes mellitus (p = 0.007) were significantly associated with spine–femur discordance in the percentage of YAM.

Conclusion

The frequency and magnitude of spine–femur discordance in the percentage of YAM from DXA scans increased with age. Notably, more than 77.4% of patients in their 90s had spine–femur discordance > 10% of YAM. Furthermore, the frequency of spine–femur discordance was higher in men and in patients with diabetes mellitus, suggesting that the percentage of YAM at the lumbar spine may not be reliable for diagnosis of osteoporosis in patients with these factors.

Preoperative Factors Associated With Low Back Pain Improvement After Total Hip Arthroplasty in a Japanese Population

BACKGROUND

Spinal disorders and low back pain (LBP) have been associated with worse clinical outcomes of total hip arthroplasty (THA). It is essential to identify spinal factors associated with post-THA LBP improvement. Therefore, we aimed to determine the proportion of patients with improved LBP after THA and to identify the preoperative spinal factors associated with LBP improvement.

METHODS

We included 151 patients who underwent primary THA between December 2015 and December 2019 and had a preoperative visual analog scale score for LBP of ≥2. The patients were classified into the LBP improved or LBP continued group based on a visual analog scale score for LBP at 1 year after THA. Preoperative spinal parameters were compared between the 2 groups.

RESULTS

Ninety-five patients (62.9%) were classified into the LBP improved group. Among the coronal spinal parameters, the Cobb angle was significantly lower in the LBP improved group. Among the sagittal spinal parameters, the LBP continued group showed a significantly more posteriorly titled pelvis, lower lumbar lordosis, greater sagittal vertical axis, and greater pelvic incidence minus lumbar lordosis mismatch, indicating a sagittal spinal imbalance. Logistic regression analysis found that preoperative factors associated with LBP improvement after THA had a low Cobb angle and high anterior pelvic plane angle (anteriorly tilted pelvis).

CONCLUSION

Among patients with LBP before THA, 62.9% had improved LBP. Sagittal spinal imbalance and high Cobb angle were the key spinal factors associated with persistent LBP. Our findings suggest that hip surgeons should evaluate spinal alignment before THA in patients with LBP.

Mechanism of Chronic Pain of Symptomatic Hip Osteoarthritis by Association of its Distribution, Nociceptive, Neuropathic, Nociplastic, or Mixed-pain Screening, and the Prevalence of Lumbar Spinal Stenosis: A Cross-sectional Study

OBJECTIVES

The pain of hip osteoarthritis (OA) is generally recognized as nociceptive in origin because of the local pathology. However, some patients with OA experience a neuropathic pain component as an essential part of some nociplastic pain subtype. Here, we sought to examine the mechanism of chronic pain of symptomatic hip OA by the association of its distribution, complex pain mechanism screening, and the prevalence of lumbar spinal stenosis.

MATERIALS AND METHODS

We conducted a prospective cross-sectional study of 100 hips in 100 patients with symptomatic hip OA in a chronic state. We examined all baseline clinical characteristics including clinical and functional score, location of pain and numbness, and pain score (PainDETECT questionnaire and the Leeds Assessment of Neuropathic Symptoms and Signs), and magnetic resonance imaging of the hip and lumbar spine.

RESULTS

The PainDETECT questionnaire and Leeds Assessment of Neuropathic Symptoms and Signs revealed that 23% of the patients had a neuropathic pain component. There were 24 variations of the pain pattern. By contrast, the pain localized around the hip joint was only 15%. Pain distal to the thigh and any numbness was significantly more frequent in the group with neuropathic pain (P<0.001). Lumbar spinal stenosis grade was not significantly different between patients with nociceptive pain and those with neuropathic pain. Pain score was significantly correlated with the pain in clinical and functional scores.

DISCUSSION

Among patients with symptomatic hip OA, the distribution of pain was various, and about 23% of patients had neuropathic, nociplastic, or mixed pain as a possibility for somatosensory system disturbances.

Sex differences in reference values of hip acetabular measurements using computed tomography in Japanese adults and the effect of aging on the measurement parameters

BACKGROUND

It is very important to understand the acetabular morphology of the normal hip joint to assist in diagnosis and surgical planning of hip disorders. The purpose of the present study was to obtain gender-based reference values for the acetabular measurements of a normal hip using computed tomography data and investigate the effect of aging on the measurement values.

METHODS

We measured acetabular parameters (center-edge angle, Sharp angle, vertical center anterior angle, acetabular anteversion) on computed tomography corrected for changing the obliquity, rotation, and tilt of the pelvis. We performed measurements in 245 patients (490 joints; 120 men [240 joints] and 125 women [250 joints]). The mean age was 64.7 ± 14.3 (31-88) years for men and 63.2 ± 15.2 (30-88) years for women.

RESULTS

In men and women, the mean center-edge angle was 31.8° ± 6.4° and 30.6° ± 6.5°, the mean Sharp angle was 38.6° ± 3.2° and 40.6° ± 3.8°, the mean vertical center anterior angle was 44.3° ± 7.9° and 40.0° ± 8.5°, and the mean acetabular anteversion angle was 14.3° ± 5.2° and 18.8° ± 5.4°, respectively. All differences were statistically significant. The center-edge angle increased with age in women; however, such an effect was not observed in men. The other measurements showed a similar trend, such as larger vertical center anterior angle and smaller Sharp and acetabular anteversion angles, with aging in both men and women.

CONCLUSIONS

We used computed tomography data to quantitatively assess the coverage and shape of the acetabulum in adult Japanese subjects and obtain the estimated reference ranges by gender. The results also proved that the measurements changed with aging in both sexes. These facts must be taken into account during the diagnosis of hip disease and planning of surgery.

Current Evidence about Developmental Dysplasia of the Hip in Pregnancy

In adults, developmental dysplasia of the hip (DDH) represents a spectrum of disorders. It is commonly found in women in routine orthopedic practice. Hip dysplasia is a leading precursor of joint laxity; when untreated, it can contribute to chronic modifications, such as thickening of the pulvinar and ligamentum teres (which can also elongate), hypertrophy of the transverse acetabular ligament, and osteoarthritis. DDH is presumed to be associated with alterations in pelvic morphology that may affect vaginal birth by the reduction in the transverse diameter of the pelvic inlet or outlet. Here, we provide an overview of the current knowledge of pregnancy-associated DDH. We primarily focused on how a surgical DDH treatment might influence the pelvic shape and size and the effects on the mechanism of birth. We presented the female pelvis from the standpoint of bone and ligament morphology relative to a pelvic osteotomy. Then, we described whether the pregnancy was impacted by previous surgical DDH treatments, performed from infancy to adulthood. In conclusion, hip dysplasia is not associated with high-risk complications during pregnancy or with increased difficulty in vaginal delivery.

Risk factors for a radiolucent line around the acetabular component with an interface bioactive bone cement technique after primary cemented total hip arthroplasty

Aims

The main aims were to identify risk factors predictive of a radiolucent line (RLL) around the acetabular component with an interface bioactive bone cement (IBBC) technique in the first year after THA, and evaluate whether these risk factors influence the development of RLLs at five and ten years after THA.

Methods

A retrospective review was undertaken of 980 primary cemented THAs in 876 patients using cemented acetabular components with the IBBC technique. The outcome variable was any RLLs that could be observed around the acetabular component at the first year after THA. Univariate analyses with univariate logistic regression and multivariate analyses with exact logistic regression were performed to identify risk factors for any RLLs based on radiological classification of hip osteoarthritis.

Results

RLLs were detected in 27.2% of patients one year postoperatively. In multivariate regression analysis controlling for confounders, atrophic osteoarthritis (odds ratio (OR) 2.17 (95% confidence interval (CI), 1.04 to 4.49); p = 0.038) and 26 mm (OR 3.23 (95% CI 1.85 to 5.66); p < 0.001) or 28 mm head diameter (OR 3.64 (95% CI 2.07 to 6.41); p < 0.001) had a significantly greater risk for any RLLs one year after surgery. Structural bone graft (OR 0.19 (95% CI 0.13 to 0.29) p < 0.001) and location of the hip centre within the true acetabular region (OR 0.15 (95% CI 0.09 to 0.24); p < 0.001) were significantly less prognostic. Improvement of the cement-bone interface including complete disappearance and poorly defined RLLs was identified in 15.1% of patients. Kaplan-Meier survival analysis for the acetabular component at ten years with revision of the acetabular component for aseptic loosening as the end point was 100.0% with a RLL and 99.1% without a RLL (95% CI 97.9 to 100). With revision of the acetabular component for any reason as the end point, the survival rate was 99.2% with a RLL (95% CI 97.6 to 100) and 96.5% without a RLL (95% CI 93.4 to 99.7).

Conclusion

This study demonstrates that acetabular bone quality, head diameter, structural bone graft, and hip centre position may influence the presence of the any RLL.

Cite this article: Bone Joint Open 2021;2(5):278–292.

Investigation of the priority among the roentgenogram measurements in acetabular dysplasia

PURPOSE

There are many radiographic parameters to evaluate developmental dysplasia of the hip joint (DDH); however, the priority between the parameters is unclear. We evaluated the priority of radiographic parameters in DDH.

METHODS

We retrospectively reviewed the radiographs of 82 consecutive patients aged above 85 years without hip osteoarthritis (OA; no osteoarthritis (NO) group), and 28 patients with early stage hip OA were set as the control group (OA group). We used the linear discriminant analysis (LDA) to consider the priority of the following parameters: acetabular roof obliquity (ARO), center-edge (CE) angle, Sharp angle, acetabular head index (AHI), and acetabular depth ratio (ADR).

RESULTS

The LDA of five different parameters revealed that the NO and OA groups could be almost distinguished with 83.6% accuracy (p < 0.0001, Wilks' lambda test). The standardized scoring coefficients were as follows: ARO, -0.23; CE, -0.43; Sharp, -0.29; AHI, 0.97; and ADR, 0.11. The AHI was particularly noticeable in the NO group.

CONCLUSION

Dissociation of the AHI in the OA group was significantly higher than that of the other parameters in the OA group compared to the parameters in the NO group. A small AHI may be a risk parameter for hip OA due to DDH.

Pelvic tilt after total hip arthroplasty in patients with osteoarthritis of the hip

BACKGROUND

It is important to understand postoperative global sagittal spinal alignment after total hip arthroplasty (THA) to prevent not only the following hip complications but also progressing lumbar degeneration. The purpose of this study was to progress the analysis of the global sagittal spinal alignment between before and after THA in patients without large lower limbs discrepancy.

SUBJECTS AND METHODS

The subjects were 87 patients with bilateral hip osteoarthritis (OA) before unilateral primary THA. We measured sagittal vertical axis (SVA), lumbar lordotic angle, sacral slope, pelvic tilt (PT), and pelvic incidence (PI) and compared the postoperative change of those parameters. Excluded criteria were Crowe classification types II, III, and IV and more than 10 mm of leg length difference, spinal scoliosis (Cobb angle > 25°), and lumbar kyphosis.

RESULTS

The correlation coefficient between preoperative factors and postoperative sagittal alignments revealed that postoperative SVA has correlation with age (r = 0.46, p < 0.008) and preoperative PT (r = 0.42, p = 0.015). Postoperative PT had a correlation with preoperative PI (r = 0.46, p = 0.007). The change of PT after operation had negative correlation to preoperative PT (r = -0.47, p < 0.01) and PI (r = -0.38, p = 0.03). Multiple regression analysis revealed that the change of PT = 4.979 - 0.235 × preoperative PT (p < 0.05). Therefore, when preoperative PT was less than 20°, the postoperative PT would become larger than the preoperative one.

CONCLUSION

(1) In patient with hip OA without large lower limbs discrepancy, the postoperative PT after THA correlated with PI. (2) The postoperative change of PT was influenced by preoperative PT.

Is Ranawat triangle method accurate in estimating hip joint center in Japanese population?

BACKGROUND

Little information has been available regarding the usefulness of Ranawat triangle method in estimating anatomical hip joint center in the Japanese population. In this study, we aimed to determine the accuracy of the method in estimating hip joint center.

METHODS

Using digitally reconstructed radiographs of 123 normal hips (123 patients), we measured the hip joint center coordinates (Cx, Cy) with reference to the ipsilateral lowest point of the teardrop, the pelvic width, and the pelvic height. Using these measurement values, we performed the following analyses: (1) the relationship of hip joint center location with pelvic dimensions; (2) accuracy of Ranawat method in estimating hip joint center; (3) alternative methods to estimate hip joint center using pelvic height.

RESULTS

The mean Cx and Cy were 32 ± 3.0 mm and 13 ± 2.1 mm, respectively. Pelvic height was positively correlated with Cx (r = 0.51, p < 0.001) and Cy (r = 0.69, p < 0.001), but the correlations of pelvic width with Cx and Cy were negligible. The mean estimation error of the Ranawat method was -6.7 ± 2.6 mm in x-axis and 6.6 ± 1.9 mm in y-axis, respectively. The hip joint center was estimated within a 5 mm error in both axes in only 8 hips (6.5%). Thus, we developed two estimating methods using pelvic height, modified Ranawat method and pelvic height ratio method, and the estimation errors of these methods were within 5 mm in both axes in 118 hips (96%) and 116 hips (94%), respectively.

CONCLUSIONS

Ranawat method showed poor accuracy in estimating anatomical hip joint center and is not recommended for clinical use. Our alternative methods may be useful for surgeons planning the position of the acetabular component in total hip arthroplasty.

Anterior pelvic plane tilt poorly estimates the sagittal body alignment due to internal rotation of innominate bone

This study investigated the influence of the rotation of innominate bone on anterior pelvic plane (APP) tilt, the angle formed by the APP, and coronal plane of the body to determine whether the provision of proper information about the sagittal balance of the body by the value of the APP tilt (APPT). In total, 244 patients (171 females, 73 males) who were candidates for total hip or knee arthroplasty, periacetabular osteotomy, or shelf arthroplasty were included. The rotational angle of the innominate bone was quantified using computed tomography images at the level of the anterior superior, and anterior inferior iliac spine, and ischiopubic portion. Clustering analysis was performed to identify subtypes of innominate bone rotation. High, intermediate, and low internal rotational alignment groups were identified in females, characterized by rotational angles. Males were treated as one group, and no intergroup differences were observed in sacral slope (SS) and pelvic incidence. However, intergroup differences in APPT were found, indicating a variation in APPT irrespective of sagittal body balance. A negligible relationship between SS and APPT was observed in the high-internal-rotation group, intermediate-internal-rotation group, and male group, whereas a moderate correlation found in the low-internal-rotation group (r = .59). The results could suggest surgeons that the value of the APPT provides no information on the sagittal balance; therefore, it may be ignored for acetabular component positioning during preoperative planning for total hip arthroplasty.

Objective characterization of hip pain levels during walking by combining quantitative electroencephalography with machine learning

Pain is an undesirable sensory experience that can induce depression and limit individuals' activities of daily living, in turn negatively impacting the labor force. Affected people frequently feel pain during activity; however, pain is subjective and difficult to judge objectively, particularly during activity. Here, we developed a system to objectively judge pain levels in walking subjects by recording their quantitative electroencephalography (qEEG) and analyzing data by machine learning. To do so, we enrolled 23 patients who had undergone total hip replacement for pain, and recorded their qEEG during a five-minute walk via a wearable device with a single electrode placed over the Fp1 region, based on the 10-20 Electrode Placement System, before and three months after surgery. We also assessed subject hip pain using a numerical rating scale. Brain wave amplitude differed significantly among subjects with different levels of hip pain at frequencies ranging from 1 to 35 Hz. qEEG data were also analyzed by a support vector machine using the Radial Basis Functional Kernel, a function used in machine learning. That approach showed that an individual's hip pain during walking can be recognized and subdivided into pain quartiles with 79.6% recognition Accuracy. Overall, we have devised an objective and non-invasive tool to monitor an individual's pain during walking.

Minimum 5 year follow-up of clinical and radiographic results of cemented acetabular components with an interface bioactive bone cement technique in primary cemented total hip arthroplasty

INTRODUCTION

A well-fixed cement-bone interface is a crucial factor for acetabular and femoral components in cemented total hip arthroplasty (THA). The aim of the present study was to evaluate the middle-term clinical and radiological results of fixing the acetabular component with an interface bioactive bone cement (IBBC) technique in primary cemented THA.

MATERIALS AND METHODS

We undertook a retrospective review was undertaken of 193 primary cemented THAs in 174 patients using acetabular components cemented with an IBBC technique and followed for a minimum of 5 years (mean 8.3 years; range 5-17 years). Baseline data, clinical and radiological outcomes were evaluated.

RESULTS

Japanese Orthopedic Association hip score and modified Harris hip scores demonstrated significant clinical improvement in all patients (p < 0.001). Radiolucent lines were detected in 15 hips (7.8%) at the first year and 24 hips (12.4%) at the final post-operative follow-up. The Kaplan-Meier survivorship with radiographic loosening as the end point was 97.8% [95% confidence interval (CI) 95.2-100]. With revision of the acetabular component for aseptic loosening as the end point, component survival was 99.0% (95% CI 97.5-100). With revision of the acetabular component for any reason as the end point, component survival was 97.0% (95% CI 93.9-100).

CONCLUSIONS

Clinical and radiological results of the acetabular component with the IBBC technique in primary cemented THA were excellent.

Treatment and Healthcare Cost Among Patients with Hip or Knee Osteoarthritis: A Cross-sectional Study Using a Real-world Claims Database in Japan Between 2013 and 2019

BACKGROUND AND OBJECTIVES

The guidelines for osteoarthritis (OA) treatment recommend different therapies including pharmacotherapy, and several analgesic options are available for pain management. In Japan, research on hip and knee OA treatment trends is scarce and OA-related healthcare costs are unknown. Therefore, this study aimed to examine the treatment and healthcare cost trends among Japanese patients with hip or knee OA.

METHODS

This was a cross-sectional study held between 2013 and 2019, using a medical claims database. The demographic and treatment characteristics of hip or knee OA patients for each year were descriptively analyzed and the medians for healthcare utilization and all-cause healthcare costs were calculated.

RESULTS

The yearly mean age of 59,218 hip OA and 270,722 knee OA patients ranged from 66.3 to 68.6 years and 71.1 to 73.1 years, respectively. The prevalence of comorbidities was higher in knee OA than hip OA. In both groups, > 70% of patients were female, and the most common treatment was pain-related medication. In hip OA, topical and systemic nonsteroidal anti-inflammatory drugs (NSAIDs) were mostly used throughout the study period (34.1-41.4% and 32.0-40.3%, respectively). Similarly, in knee OA, topical and systemic NSAIDs were used in 58.3-63.3% and 36.5-46.0% patients, respectively. Increase in the use of acetaminophens (10.9% in hip OA and 10.2% in the knee OA) and weak opioids (3.7%, and 3.4%, respectively) from 2013 to 2019 were observed. Most patients were treated as outpatients in both groups. The median all-cause healthcare costs were approximately 35,000 JPY for hip OA and 74,000 JPY for knee OA.

CONCLUSIONS

Although a considerable change in total healthcare cost was not observed in our study, the contents of medical treatment and cost breakdown were greatly altered due to the treatment and cost for OA itself, and the treatment and cost for comorbidities. Similar studies to investigate such a trend may help predict necessary resources and social needs. Thus, further investigation utilizing other databases is needed.

Factors associated with health-related quality of life in Japanese patients with hip osteoarthritis: A cross-sectional study

Background/Purpose:

Chronic symptoms related with hip osteoarthritis (OA) can negatively affect health-related quality of life (HRQoL). The purpose of this study was to examine factors related to a HRQoL measure that considers an Asian lifestyle in Japanese patients with hip OA.

Methods:

Forty-seven female subjects participated. The dependent variable was the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ), which assessed HRQoL. Potential factors were measured as independent variables. After screening, potential variables were entered into a multiple regression analysis to determine which variables were related to HRQoL.

Results:

In the regression model, knee extension muscle strength on the unaffected side and hip flexion range of motion (ROM) on the affected side were associated with HRQoL. Higher strength and higher ROM were related to greater HRQoL.

Conclusion:

Results can help health-care providers develop appropriate rehabilitation programs for improving HRQoL in patients with hip OA.

Low prevalence of radiographic hip osteoarthritis and its discordance with hip pain: A nationwide study in Korea

AIM

This study aimed to evaluate the prevalence and associated factors of radiographic hip osteoarthritis (OA) in the Korean community-dwelling population.

METHODS

This study included 11 814 individuals (5025 men and 6789 women) ≥50 years of age from the Korea National Health and Nutrition Examination Surveys. Radiographic hip OA was defined as having a Kellgren-Lawrence grading scale score ≥2. Painful hip OA was defined as radiographic hip OA with the presence of hip pain. The prevalence of radiographic hip OA was evaluated with respect to age group, sex and presence of hip pain. The associations of sociodemographic and clinical variables with hip OA and hip pain were assessed using multivariable logistic regression analyses.

RESULTS

The weighted prevalence of radiographic hip OA and painful hip OA was 1.1% and 0.2%, respectively, in Korea. Older age (≥75 years) and male sex were independently associated with radiographic hip OA and painless hip OA. Comorbid musculoskeletal pain (knee pain) was independently associated with painful hip OA. The difference between painful and painless hip OA was the presence of comorbid musculoskeletal pain (knee pain and low back pain). Although hip pain was more common in women than in men, it was associated with the severity of hip OA only in men.

CONCLUSIONS

Radiographic hip OA is rare in Korean middle-aged and elderly people. Furthermore, hip pain is infrequent in radiographic hip OA. Geriatr Gerontol Int 2021; 21: 20-26.

Radiographic characteristics of the hip joint in skeletally mature patients with multiple hereditary exostoses

OBJECTIVE

To elucidate the radiological characteristics of the hips, especially in proximal femur, of skeletally mature patients with multiple hereditary exostoses (MHE).

MATERIALS AND METHODS

Fifty eligible patients (100 hips) were included in the study and assigned to the MHE group. The control group included age- and sex-matched individuals, and the radiographs of 100 hips were used as controls. We examined the anatomical characteristics of the acetabulum and the proximal femur, including the acetabular depth-width ratio (ADR), Sharp's angle, femoral neck-shaft angle (NSA), Wiberg's centre-edge angle (CEA), femoral neck axis length (FNAL), femoral head diameter, (FHD), femoral neck width (FNW), femoral shaft width (FSW), femoral neck-shaft angle (NSA), and femoral head-neck ratio (FHNR = FHD/FNW). p value < 0.05 was considered significant.

RESULTS

Osteochondroma was frequently observed in the medial femoral neck (79%), but it was rarely found in the femoral head (1%). ADR and Sharp's angle were not significantly different between the MHE and control groups (p = 0.2056, p = 0.5025). CEA was significantly different between the two groups (p < 0.0001). FNW was significantly larger in the MHE group than in the control group (p < 0.0001). FHNR was significantly different between the two groups (p < 0.0001). NSA was significantly larger than the MHE group (141.8° ± 9.7° vs 129.5° ± 5.6°, p < 0.0001).

CONCLUSIONS

Hip dysplasia in the pelvic side was not commonly observed in skeletally mature MHE patients. However, they showed femoral neck widening and coxa valga. The occurrence of osteochondroma around the femoral neck affects the degree of valgus deformity. These facts could be useful for orthopaedic surgeons treating MHE patients.

Racial/Ethnic, Socioeconomic, and Geographic Disparities in the Epidemiology of Knee and Hip Osteoarthritis

It is estimated that 32.5 million US adults have clinical osteoarthritis (OA), with the most common sites being knee and hip. OA is associated with substantial individual and societal costs. Race/ethnicity, socioeconomic status (SES), and geographic variations in the prevalence of knee and hip OA are well established around the world. In addition, clinical outcomes associated with hip and knee OA differ according to race/ethnicity, SES, and geography. This variation is likely multifactorial and may also reflect country-specific differences in health care systems. The interplay between different factors, such as geography, SES, and race/ethnicity, is difficult to study.

CT Based Analysis of Acetabular Morphology in Northern Indian Population: A Retrospective Study

PURPOSE

The acetabular morphology has shown to differ among different regions of the world. Multiplanar evaluation by computed tomography (CT) scan is the key to assess acetabular depth, version, and inclination at the same time which have been rarely explored before in the Indian population. We present an anthropometric study of the native acetabulum by CT based coronal, sagittal, and axial parameters in the Northern Indian population.

METHODS

The acetabular anteversion (AA), acetabular angle of sharp (AAS), sagittal acetabular angle (SAA), lateral center edge angle (LCEA), acetabular depth (AD), acetabular horizontal offset (AHO), extrusion index (EI) and acetabular depth ratio (ADR) was measured in CT scans of 122 patients (244 hips) without any bony pathologies. LCEA < 20°, ADR < 250, AD < 9 mm, AAS > 43°, and EI ≥ 25% were taken as criteria for dysplastic acetabulum.

RESULTS

There were 62 males and 60 females included in the study with a mean age of 63.8 ± 17.2 years (21-98 years). In this study, females were having significantly lower ADR (p = 0.002) and higher EI (p = 0.01) than males. The prevalence of dysplasia was 3.2% according to LCEA and 1.6% while combining all of the criteria.

CONCLUSION

There are prominent differences in acetabular depth in the Indian population compared with the population of Western countries or other parts of Asia. Females were shown to have shallower acetabulum than males. The comparative analysis of radiographic parameters obtained from our study with the data available on different country-based studies can help better understanding the acetabular morphology of Indian as well as the worldwide population.

LEVEL OF STUDY

Retrospective cross-sectional study.

Modified lateralized head sign: An accurate marker in diagnosing adult hip dysplasia

BACKGROUND

Although lateralized head sign (LHS) is considered indicative of structural instability, it lacks reproducibility, and its usefulness in diagnosing adult hip dysplasia is unknown. In this study, we proposed a modified LHS and aimed to determine its reliability and accuracy in diagnosing adult hip dysplasia.

METHODS

We reviewed anteroposterior pelvic radiographs of 94 patients (134 hips) with hip dysplasia. As controls, 133 normal hips were evaluated. We defined the modified lateralization distance (LD) as the horizontal distance between the medial aspect of the femoral head to the acetabular fossa. The sensitivity, specificity, and cutoff value of modified LD in diagnosing hip dysplasia were calculated using receiver operating characteristic curve analysis.

RESULTS

The sensitivity and specificity of the modified LD (79% and 87%, respectively) were higher than those of the conventional LD (63% and 80%, respectively). Diagnostic accuracy was further improved when patients were divided on the basis of sex. The sensitivity and specificity of the modified LD in men were 89% and 97%, respectively, with a cutoff value of 12 mm, while in women, they were 80% and 96%, respectively, with a cutoff value of 9.7 mm. Therefore, we defined the modified LHS as presentation with a modified LD ≥ 12 mm in men and ≥10 mm in women. Between three observers, the kappa value for intraobserver reliability was ≥0.9, while that for interobserver reliability was >0.8. The mean sensitivity and specificity of the modified LHS in diagnosing hip dysplasia were 85% and 99%, respectively.

CONCLUSIONS

Modified LHS-a horizontal distance between the medial aspect of the femoral head and the acetabular fossa ≥12 mm in men and ≥10 mm in women-is a clinically useful marker in detecting lateral femoral head subluxation indicative of hip dysplasia or structural hip instability.

Long-Term Outcomes of Eccentric Rotational Acetabular Osteotomy Combined With Femoral Osteotomy for Hip Dysplasia

BACKGROUND

This study aimed at investigating the clinical outcomes of eccentric rotational acetabular osteotomy (ERAO) combined with intertrochanteric valgus osteotomy (ITVO) over a period of more than 10 years.

METHODS

This is a case-control study of 39 patients (40 hips) who underwent ERAO combined with ITVO for hip dysplasia (ITVO group). Patients were matched for age, sex, follow-up period, and preoperative joint stage to 78 patients (80 hips) who underwent ERAO alone (ERAO group). We compared the clinical and radiographic outcomes and the survival rates between the groups.

RESULTS

The Harris Hip Score at the final follow-up was significantly lower in the ITVO group than in the ERAO group. The postoperative center edge angle, acetabular head index, and minimum joint space were significantly smaller in the ITVO group than in the ERAO group. The survival rates for the conversion to total hip arthroplasty end point were not significantly different between groups. However, survival rates for the Harris Hip Score < 80 end point were significantly poorer in the ITVO group than in the ERAO group.

CONCLUSION

The long-term results of ERAO combined with ITVO were not satisfactory from a hip function perspective. ERAO combined with ITVO should be indicated in only young active patients with pre-osteoarthritis and initial stages of osteoarthritis.

Editorial Commentary: A-version to a Pain in the Butt-Structural and Dynamic Determinants of Posterior Hip Pain

Ischiofemoral impingement is becoming a more recognized source of buttock pain that occurs as the lesser trochanter of the femur approximates the lateral margin of the ischium. Abnormal bony structure and alignment of the hip joint and/or faulty dynamic movement patterns may decrease the ischiofemoral space and compress the structures that are found within the space, including the quadratus femoris, proximal hamstring tendons, and sciatic nerve. The ischiofemoral space is reduced by structural factors including an increase in femoral anteversion and femoral neck angle. Dynamic assessment of the hip region may include the Craig test and total rotational range of motion of the hip joint, as well as the ischiofemoral impingement test and the long-stride walking test. The combination of structural and dynamic assessment of the hip region may help determine the presence of ischiofemoral impingement and direct appropriate management of the condition.

Morphological risk factors associated with dislocation after bipolar hemiarthroplasty of the hip in patients with femoral neck fractures-a nested case-control study

Background

The relationship between preoperative hip measurements and dislocation after bipolar hemiarthroplasty is presently unclear. In the current study, we investigated the morphological risk factors associated with dislocation after bipolar hemiarthroplasty of the hip in patients with femoral neck fractures.

Methods

Between January 2011 and June 2017, a nested case-control design study was used to analyze the risk factors for dislocation in 348 patients who had undergone bipolar hemiarthroplasty because of femoral neck fractures. Twelve patients underwent at least one dislocation postoperatively. Sixty patients without dislocation were selected as controls matched in terms of time of surgery, age, and sex, at a ratio of 1:5. Patient acetabular measurements were compared between the dislocation group and the control group, including the center-edge angle, abduction angle, acetabular width and depth, depth-to-width ratio, femoral neck offset, leg length discrepancy, and femoral head coverage ratio. A multivariate logistic regression model was used to evaluate the morphological risk factors of dislocation.

Results

Postoperatively, the incidence of dislocation was 3.4%. A smaller center-edge angle was found to be a risk factor associated with dislocation after bipolar hemiarthroplasty of the hip. Patients with small acetabular depth and a small acetabular depth–width ratio were prone to dislocation. Patients with a center-edge angle of ≤ 45.4° or an acetabular depth of ≤ 19.12 mm were more likely to suffer dislocation.

Conclusions

Careful preoperative measurements before bipolar hemiarthroplasty of the hip are important. Surgical intervention for femoral neck fracture patients with a shallow acetabulum should be carefully planned and total hip arthroplasty should be considered when necessary.

Does Acetabular Coverage Vary Between the Supine and Standing Positions in Patients with Hip Dysplasia?

BACKGROUND

Although variation in physiologic pelvic tilt may affect acetabular version and coverage, postural change in pelvic tilt in patients with hip dysplasia who are candidates for hip preservation surgery has not been well characterized, and its clinical importance is unknown.

QUESTIONS/PURPOSES

The aim of this study was to determine (1) postural changes in sagittal pelvic tilt between the supine and standing positions; (2) postural changes in the acetabular orientation and coverage of the femoral head between the supine and standing positions; and (3) patient demographic and morphologic factors associated with sagittal pelvic tilt.

METHODS

Between 2009 and 2016, 102 patients underwent pelvic osteotomy to treat hip dysplasia. All patients had supine and standing AP pelvic radiographs and pelvic CT images taken during their preoperative examination. Ninety-five patients with hip dysplasia (lateral center-edge angle < 20°) younger than 60 years old were included. Patients with advanced osteoarthritis, other hip disease, prior hip or spine surgery, femoral head deformity, or inadequate imaging were excluded. Sixty-five patients (64%) were eligible for participation in this retrospective study. Two board-certified orthopaedic surgeons (TT and MF) investigated sagittal pelvic tilt, spinopelvic parameters, and acetabular version and coverage using pelvic radiographs and CT images. Intra- and interobserver reliabilities, evaluated using the intraclass correlation coefficient (0.90 to 0.98, 0.93 to 0.99, and 0.87 to 0.96, respectively), were excellent. Demographic data (age, gender, and BMI) were collected by medical record review. Sagittal pelvic tilt was quantified as the angle formed by the anterior pelvic plane and a z-axis (anterior pelvic plane angle). Using a 2D-3D matching technique, we measured the change in sagittal pelvic tilt, acetabular version, and three-dimensional coverage between the supine and standing positions. We correlated sagittal pelvic tilt with demographic and CT measurement parameters using Pearson's or Spearman's correlation coefficients.

RESULTS

Although functional pelvic tilt varied widely among individuals, the pelvis of patients with hip dysplasia tilted posteriorly from the supine to the standing position (mean APP angle 8° ± 6° versus 2° ± 7°; mean difference -6°; 95% CI, -7° to -5°; range -17° to 4.1°; p < 0.001; paired t-test).The pelvis tilted more than 5° posteriorly from the supine to the standing position in 39 patients (60%), and the change was greater than 10° in 12 (18%). In the latter subgroup of patients, the mean acetabular anteversion angle increased (22° ± 5° versus 27° ±5°; mean difference 5°; 95% CI, 4°-6°; p < 0.001) and the mean anterosuperior acetabular sector angle notably deceased from the supine to the standing position (91° ± 11° versus 77° ± 14°; mean difference -14°; 95% CI, -17° to -11°; p < 0.001; paired t-test). Postural change in pelvic tilt was not associated with any of the studied demographic or morphologic parameters, including patient age, gender, BMI, and acetabular version and coverage.

CONCLUSIONS

On average, the pelvis tilted posteriorly from the supine to the standing position in patients with hip dysplasia, resulting in increased acetabular version and decreased anterosuperior acetabular coverage in the standing position. Thus, assessment with a supine AP pelvic radiograph may overlook changes in acetabular version and coverage in weightbearing positions. We recommend assessing postural change in sagittal pelvic tilt when diagnosing hip dysplasia and planning hip preservation surgery. Further studies are needed to determine how postural changes in sagittal pelvic tilt affect the biomechanical environment of the hip and the clinical results of acetabular reorientation osteotomy.

LEVEL OF EVIDENCE

Level IV, diagnostic study.

Comparison of four parameters to assess acetabular dysplasia and acetabular dysplasia rates in primary hip osteoarthritis patients: A study in Turkish population

INTRODUCTION

Hip osteoarthritis is an important orthopedic problem frequently observed in the elderly. Acetabular dysplasia (AD) is one of the pathologies that cause coxarthrosis. Nearly 20-45% of primary or idiopathic hip osteoarthritis is linked to AD. In our country, there are few studies on this topic. We measured the center-edge (CE) angle, Sharp's angle, acetabular depth, and femoral head coverage ratio on pelvis anteroposterior radiographs of patients with primary coxarthrosis and calculated the dysplasia rates.

PATIENTS AND METHOD

Age at surgery and sex of the patients; and CE angle, Sharp's angle, acetabular depth, and femoral head coverage ratio for both operated and opposite hips were evaluated in 223 total hip prosthesis-performed patients with coxarthrosis. Also the distribution of mean age at surgery, sex of patients, dysplasia rates of operated hips, and bilateral dysplasia rates were calculated.

RESULTS

The right to left ratio of operated hips was 104/119. Female to male ratio was 163/60 (2.7/1), for those with CE angle below 20° it was 123/30 (4.1/1), and it was 40/30 (1.3/1) with CE angle above 20°. Mean age of patients at surgery was 56.9 (±11.4) years. CE angle less than 20° was found in 68.6% of patients, acetabulum depth less than 9 mm was found in 75.3%, Sharp's angle was more than 45° in 65.9%, and femoral head coverage ratio was less than 70% in 70.3% of patients.

CONCLUSIONS

We identified a high rate of AD in primary coxarthrosis patients undergoing total hip arthroplasty in the study population.

Prevalence of radiologic acetabular dysplasia in asymptomatic Asian volunteers

The purpose of this study was to evaluate the prevalence of acetabular dysplasia in an asymptomatic Asian population as one of the most important risk factors of hip osteoarthritis. From December 2014 to March 2015, we investigated the data of 200 asymptomatic volunteers (400 hips) aged 18–50 years recruited from our institution. Pelvic radiographs were taken and reviewed by two experienced orthopaedic surgeons. Lateral centre-edge (LCE) angle, Sharp angle, Tonnis angle and acetabular depth-to-width ratio (AD/WR) were measured. We investigated the mean values and identified the statistical differences between the sexes and evaluated the prevalence and bilaterality of acetabular dysplasia defined by each parameter. Mean LCE angle, Sharp angle, Tonnis angle and AD/WR were 26.2°, 41.3°, 8.5° and 0.28, respectively. All parameters showed more dysplastic results in females than in males and were statistically significantly different, except for AD/WR. When defined acetabular dysplasia as LCE angle <20°, Sharp angle >45°, Tonnis angle >14° or AD/WR <0.25, the prevalence of acetabular dysplasia by each parameter was 15.0%, 12.8%, 13.3% and 12.8%, respectively. There was a higher prevalence in females than in males; however, only Sharp and Tonnis angles showed significant differences. The bilaterality of acetabular dysplasia was 18.6–39.5% for all subjects. There is high prevalence of asymptomatic dysplastic hips in the Asian population.

What Are the Reference Values and Associated Factors for Center-edge Angle and Alpha Angle? A Population-based Study

BACKGROUND

The available evidence regarding normal ranges for the center-edge angle and the alpha angle derives from a few small studies, and associated factors such as sex and anthropometric factors have not been well evaluated. Knowing more about normal values for these parameters is critical, because this can inform decisions about when to perform elective hip preservation surgery. Population-level studies would provide considerable clarity on these issues, but to our knowledge, no such studies are available.

QUESTIONS/PURPOSES

The purposes of this study were (1) to use MRI in patients of a population-based study to establish normal values for the alpha and center-edge angles in the normal adult hip; and (2) to determine whether age, sex, or anthropometric variables were associated with differences in these values.

METHODS

We used MRI images (1.5 T) of 3226 participants of the Study of Health in Pomerania (SHIP). SHIP is a population-based study that started with 4308 participants in 1997. Participants were recruited randomly from official inhabitant data files as a stratified cluster sample of the population from a defined region in northeastern Germany. To ensure a representative epidemiologic cohort, stratification variables were sex, age, and city of residence. Between 2008 and 2012, 1094 of these participants underwent whole-body MRI with pelvic sequences in the second followup. In parallel, the next cohort, SHIP-Trend, started with the same protocol in which 2132 participants underwent MRI examination. Reference values were calculated by quantile regressions for the 2.5 and 97.5 percentiles. Associations with the demographic features sex, age, weight, height, body mass index (BMI), and waist circumference were analyzed by bivariate linear regression models.

RESULTS

The mean center-edge angle was 31° (± 7°) with a corresponding calculated normal range of 17° to 45°. The mean alpha angle was 55° (± 8°) with a corresponding calculated normal range between 39° and 71°. Men (30° ± 7°) had a lower center-edge angle than women (32° ± 8°) (p < 0.001, β = 1.4°; 95% confidence interval [CI], 0.9°-1.9°) and a higher alpha angle (57° ± 8° versus 52° ± 7°, p < 0.001, β = 5.7°; 95% CI, 5.2°-6.3°). Moreover, a higher center-edge angle for the left side was found (33° ± 8° versus 30° ± 8°, p < 0.001, β =3.2°; 95% CI, 3.0°-3.4°). In addition to sex, we found that age, height, waist circumference, and BMI affected both center-edge angle and alpha angle. Weight was associated with the alpha angle as well. Because of these associations, age- and sex-adjusted reference values with belonging formulas were calculated.

CONCLUSIONS

The range of normal center-edge and alpha angles is quite wide. Therefore, only markedly abnormal angles may be associated with pathology. Moreover, center-edge angle and alpha angle are associated with age, sex, and anthropometric factors, which have to be taken into account for better interpretation.

CLINICAL RELEVANCE

The association of abnormal radiographic values with true clinical hip pathology is tenuous at best. Assuming that a patient with an abnormal radiograph requires treatment is unwise. The clinical picture has to be substantial for therapeutic decisions.

Hemi-pelvic slope is correlated with the acetabular depth in adults-a radiological study

OBJECTIVE

The purpose of this study was to determine if there is an anatomic relationship between pelvic geometry and acetabular depth.

MATERIALS AND METHODS

One hundred and fifty-one anteroposterior pelvic radiographs (157 hip joints) were selected and analyzed in a retrospective fashion. Six parameters, including iliac offset, ischial offset, acetabular offset, pelvic height, center-edge (CE) angle of Wiberg, and acetabular index (AI) angle of Tönnis were measured for each of the hip joints. Based on the defined variables, three formulas (formulas 1, 2, and 3) were calculated to represent the hemi-pelvis slope.

RESULTS

There was a strong relationship between the hemi-pelvis slope and probability of acetabular dysplasia. Wider upper pelvis was associated with deeper acetabulum and wider lower pelvis was associated with dysplastic acetabulum.

CONCLUSIONS

Pelvic anatomic dimensions and the relationship between them are strongly correlated with hip dysplasia indices. Dysplastic hips tend to be found in pelvises with lower slope (low width of the upper pelvis at the level of iliac crest and high width of the lower part at the level of ischium).

A whole-genome transcriptome analysis of articular chondrocytes in secondary osteoarthritis of the hip

Objective

To date, exhaustive gene expression analyses of chondrocytes in hip osteoarthritis (OA) have yielded specific gene expression patterns. No study has reported on the exhaustive transcriptome of secondary hip OA based on acetabular dysplasia in a Japanese population, while previous reports have focused on primary or idiopathic hip OA in Caucasian populations. This study aims to search for specific gene expression patterns of secondary hip OA chondrocytes by transcriptome analysis.

Design

Human articular cartilage was obtained from femoral heads following hemiarthroplasty for femoral neck fracture (N = 8; non-OA) and total hip arthroplasty for secondary hip OA (N = 12). Total RNA was extracted from the articular cartilage and submitted for microarray analysis. The obtained data were used to perform gene expression analysis, GO enrichment analysis and pathway analysis and were compared with data from primary hip OA in Caucasian populations in the literature.

Results

We identified 888 upregulated (fold change: FC ≥ 2) and 732 downregulated (FC ≤ 0.5) genes in hip OA versus non-OA chondrocytes, respectively. Only 10% of upregulated genes were common between the secondary and primary OA. The newly found genes prominently overexpressed in the secondary hip OA chondrocytes were DPT, IGFBP7, and KLF2. Pathway analysis revealed extracellular matrix (ECM)-receptor interaction as an OA-related pathway, which was similar to previous reports in primary hip OA.

Conclusions

This is the first study to report the genome-wide transcriptome of secondary hip OA chondrocytes and demonstrates new potential OA-related genes. Gene expression patterns were different between secondary and primary hip OA, although the results of pathway and functional analysis were similar.