Osteoarthritis In Dysplastic Hips Research Articles

Characteristics of pelvic obliquity in dysplastic hip osteoarthritis.

Factors affecting direction of pelvic obliquity (PO) in dysplastic hip osteoarthritis (DHOA) remains unclear. This retrospective cohort study evaluates morphological characteristics, spinal alignment, and hip function in patients with unilateral DHOA. Between 2018 and 2022, 104 patients with unilateral DHA were enrolled. Patients were categorized into flat PO (F-PO group; PO < 2°), affected side PO (A-PO group; PO downward by ≥ 2°), and unaffected side PO (U-PO group; PO upward by ≥ 2°). Demographics, radiographic hip and lower limb parameters, spinal parameters, and functional scores were compared between the groups. There were 39, 44, and 21 patients in the F-PO, A-PO, and U-PO group, respectively. The subluxation percentage of Crowe classification showed a significant difference among the three groups. The femoral head lateralization distance was significantly greater in the U-PO group than in the F-PO and A-PO groups. Furthermore, the hip adduction angle was significantly lower in the A-PO group than in the F-PO and U-PO groups. The lumbar scoliosis angle was significantly different between the groups. In multivariate analysis, hip adduction angle was extracted as an independent factor associated with the A-PO. Age, subluxation percentage, and hip adduction angle were identified as independent factors associated with the U-PO. Harris hip score was significantly poorer in U-PO group than in F-PO group. Hip adduction angle influenced A-PO, while age, subluxation percentage, and hip adduction angle influenced U-PO; lumbar scoliosis angle was associated with PO direction. U-PO patients had poorer functional scores, indicating the impact of hip contracture and subluxation on PO direction in DHOA.

Computer simulation study of cementless cup placement for dysplastic hip osteoarthritis using subluxation percentage of Crowe classification.

It is often difficult to achieve adequate bone coverage of the cup in total hip arthroplasty in cases of severe developmental dysplasia of the hip (DDH). This study aimed to evaluate the relationship between subluxation percentage of Crowe classification and cup center-edge (cup-CE) angle to investigate whether subluxation percentage according to the Crowe classification is a useful indicator for cementless cup placement. Cementless cup placement was simulated in 77 women with DDH in 91 hips (Crowe I, 35 hips; Crowe II, 35 hips; and Crowe III, 21 hips) using computed tomography-based computer simulation software. The cups were placed at the anatomic hip center (AHC) and 10-mm high hip center (HHC). The relationship between the subluxation percentage and cup-CE angle was evaluated using Spearman's rank correlation coefficient. In addition, the cutoff values for the subluxation percentage that satisfied a cup-CE angle ≥0° were determined using the receiving operating characteristic curve. The cup-CE angle was negatively correlated with the subluxation percentage in both AHC and 10-mm HHC (correlation coefficient ρ = -0.542 [p < 0.01] and -0.704 [p < 0.01], respectively). The cutoff values for subluxation percentage that satisfied a cup-CE angle ≥0° were 56.1% and 73.6% for AHC and 10-mm HHC, respectively. Cementless cup placement in AHC is difficult in cases with the subluxation percentage ≥56.1%, and HHC reconstruction or femoral structural autograft technique should be considered as an alternative. Moreover, placement at 10 mm above AHC is difficult in cases with subluxation percentage ≥73.6%.

Fall risk in patient with dysplastic hip osteoarthritis.

Patients with dysplastic hip osteo arthritis (DHOA) often have a spinopelvic imbalance, and they are more likely to experience falls. This study aimed to evaluate the risk factors for falls in patients with DHOA, including spinopelvic parameters. In this cross-sectional study, a total of 103 patients with DHOA were included from 2019 to 2021. Fall risk was evaluated using the Fall Risk Index 5 items version (FRI-5). Demographics, functional outcomes, and spinopelvic parameters were compared between the high-risk group (FRI-5 ≥ 6) and the low-risk group (FRI-5 < 6). Multivariate analysis was performed using factors with significant differences in univariate analysis. High-risk and low-risk groups comprised 54 and 49 patients, respectively. Females were significantly more common in the high-risk group than in the low-risk group. The Harris Hip Score was significantly lower in the high-risk group than in the low-risk group (p = 0.02). Pelvic incidence, tilt, and obliquity were significantly higher in the high-risk group than in the low-risk group (p < 0.01). In multivariate analysis, female sex (odds ratio [OR]: 3.76, 95% confidence interval [CI]: 1.11-12.64, p = 0.03), pelvic obliquity (OR: 1.36, 95% CI: 1.09-1.71, p < 0.01), and Harris hip score (OR: 0.96, 95% CI: 0.93-0.99, p = 0.02) were identified as risk factors. Female sex, pelvic obliquity, and low Harris hip score were associated with an increased risk of falls among patients with DHOA.

Percutaneous Partial Tenotomy of ITB for Secondary Genu Valgum Developing After Total Hip Arthroplasty ın Patients wıth Crowe Type-Iv Dysplasia.

The aim of this study was to make a prospective evaluation of the effect on the clinical results of percutaneous iliotibial band partial tenotomy (PITP) applied to cases of genu valgum which developed following total hip prosthesis for Crowe Type IV dysplastic hip. The study consists of 33 patients with unilateral crowe type IV dysplastic hip osteoarthritis who developed iatrogenic ipsilateral genu valgum after total hip arthroplasty. The patients were randomly separated into 2 groups of Group 1 (n = 16) where percutaneous iliotibial band tricut partial tenotomy was applied (PITP) and Group 2 (n = 17) where no treatment was applied. Pre and postoperative measurements were taken of the Harris Hip Score (HHS), the Lysholm-Gilquist Knee Score (LGS), Visual Analog Score (VAS), ipsilateral knee Q angle, and the spina ilica anterior superior medial malleolus distance (SIAS-MM). In both Group 1 and Group 2, a statistically significant increase was seen in the values of SIAS-MM (p < 0.001), Q angle (p < 0.001) and HSS (p < 0.001) from preoperative to postoperative. A statistically significant decrease was determined in LGS (p < 0.001, p < 0.003). In Group 1, a statistically significant decrease in the Q angle was determined at the final follow-up after PITP compared to the early postoperative period (p < 0.001). The HSS values for Group 1 were statistically significantly high in the early postoperative period and at the final follow-up (p < 0.001). PITP application improves knee and hip clinical scores in the early postoperative period and hip clinical scores in the mid-term follow-up.

Factors influencing inconsistent leg length discrepancy in dysplastic hip osteoarthritis: a retrospective study

BackgroundWe aimed to examine the inconsistency between radiographic leg length discrepancy (R-LLD) and perceived LLD (P-LLD) in patients with dysplastic hip osteoarthritis and to evaluate the factors that can cause such inconsistency.MethodsWe conducted a retrospective study on 120 patients. An inconsistent LLD was defined as a condition in which the P-LLD was shorter than the R-LLD by > 5 mm. We compared relevant data on the general characteristics of the patients and the radiological findings between consistent (group E, 92 cases [76.7%]) and inconsistent LLDs (group S, 28 cases [23.3%]).ResultsThe number of patients with a history of hip surgery on the affected side and the Japanese Orthopedic Association classification pain scores were significantly higher in group S than in group E (32.1% vs. 10.8%, respectively; P = 0.015, and 21.7 ± 7.0 vs. 17.5 ± 8.2, respectively; P = 0.036). The pelvic oblique angle and length of the R-LLD were significantly higher in group S than in group E (2.9 ± 2.5° vs. 0.3 ± 2.3°, respectively; P < 0.01, and 17.2 ± 8.9 mm vs. 6.3 ± 8.4 mm, respectively; P < 0.01). Multivariate logistic analysis revealed that the pelvic oblique angle (odds ratio [OR]: 1.80, 95% confidence interval [CI]: 1.28–2.52; P < 0.01) and length of the R-LLD (OR: 2.75, 95% CI: 1.24–6.12; P = 0.013) were independent risk factors of inconsistent LLD.ConclusionThe pelvic oblique angle and a long R-LLD were independent risk factors of inconsistent LLD in patients with dysplastic hip osteoarthritis. Therefore, hip surgeons should consider P-LLD rather than R-LLD to understand the need for conservative intervention.

The fate of femoral head autograft in acetabular reconstruction in dysplastic hips at midterm.

To evaluate the acetabular cup and graft survival in patients who underwent total hip arthroplasty (THA) with the diagnosis of dysplastic hip osteoarthritis and received a femoral head autograft due to acetabular coverage deficiency. Between January 2005 and December 2016, 83 hip prostheses of 80 patients who underwent THA using femoral head autografts and were followed up for at least 2 years were retrospectively evaluated. Seventy-four hips of the remaining 71 patients (57 female (80%)) were included. Mean patient age at surgery was 51 ± 16 (range 18-76) years. The mean follow-up duration was 76 ± 25 (range 25-161) months. Acetabular inclination and graft thickness, contact length, percentage of coverage, and graft resorption were examined on postoperative and final follow-up radiographs. The presence of a radiolucent area around the acetabular and femoral components indicating loosening was also evaluated. The mean postoperative acetabular component inclination was 44 ± 5.1° (range 30-48°) with mean graft coverage of 34 ± 4.8% (range 24-46%). In all patients, autograft union with the pelvis was seen and the lateral overflow was remodeled. Fifteen patients (20%) underwent revision surgery due to aseptic acetabular component loosening in four, nontraumatic recurrent dislocations in eight, periprosthetic infection in one, acetabular component protrusion in one, and traumatic hip dislocation in one. In patients with osteoarthritis secondary to developmental hip dysplasia, the use of femoral head autografts to eliminate acetabular coverage deficiency during THA achieves acceptable midterm postoperative radiological outcomes. Increased acetabular bone stock may be beneficial in possible future revision surgeries.

Why do subchondral cysts occur at the medial aspect of the femoral head in hip dysplasia?

Osteoarthritis in dysplastic hips should develop from the lateral side of the acetabulum and the femoral head just below. However, the existence of subchondral cysts located more on the medial side contradicts the weight-loading theory. The aim of this study was to confirm the presence of medial cysts at the femoral head and to investigate the relationship between medial cysts and injuries of the ligamentum teres in hip dysplasia. A retrospective analysis was conducted on 257 cases of hip dysplasia. All patients had x-rays and 3-dimensional computed tomographies (3D CT) preoperatively and 123 patients had magnetic resonance arthrographies. A comparison was performed between cases with and without medial cysts according to the severity of damage to the ligamentum teres, the presence of bony spurs around the fovea capitis, and the Tönnis grade. Medial subchondral cysts around the fovea capitis were found in 100 cases. Mild osteoarthritis (Tönnis grade 0 or 1) was present in 89% of cases in the medial cyst group. A significant difference between the groups was observed in the incidence of bony spurs around the fovea capitis (p < 0.05) and injuries of the ligamentum teres (p < 0.05). The formation of subchondral cysts at the medial femoral head in hip dysplasia may be related to damage in the ligamentum teres. Considering that subchondral cysts develop in early osteoarthritis, the progression of arthritis in hip dysplasia appears to correlate with damage to the ligamentum teres, as well as compressive pressure on the joint.

Choice of the Acetabular Component Placement in Dysplastic Hip Patients

Abstract Total hip arthroplasty (THA) in patients with hip dysplasia is a challenging surgical operation. Many orthopedic surgeons concur that the anatomical placement of the acetabular components of endoprostheses (AC-EPs) during THA yields the best result. However, there are advocates of the high rotation center of the hip joint after replacement surgery. In our study, we compared the outcomes of THA based on the placement of acetabular cups to identify the most favorable site for AC-EPs in patients with varying grades of dysplastic osteoarthritis. Our study included 88 patients with dysplastic hip osteoarthritis who underwent 106 THAs during a three-year period using cementless fixation endoprostheses. Functional results were assessed by Merle d’Aubigne and Postel’s method and by instrumental gait analysis (IGA). Gait deviation index was calculated based on IGA to compare results in different acetabular component placement groups. Functional assessment of patients by Merle d’Aubigne and Postel’s grading method and IGA showed no significant difference in results due to the placement of the acetabular component. Most complications were found in the severe dysplasia patients group with the anatomical placement of the AC-EP. The appropriate location of cementless acetabular cups during THA in dysplastic hips depends on the grade of dysplasia, expected elongation of the leg, and the potential for adequate bone coverage for the AC-EP. In cases of severe dysplasia, the placement of the AC-EP in the secondary socket can provide a good functional outcome and reduce the risk of complications.

Primary Total Hip Arthroplasty in Severe Dysplastic Hip Osteoarthritis With a Far Proximal Cup Position

BackgroundDevelopmental hip dysplasia is the most common cause of secondary hip osteoarthritis. Due to severe acetabular bone deficiency, cup positioning in total hip arthroplasty (THA) of dysplastic hips remains a surgical challenge. The aim was to analyze the functional outcome of far proximal cup positions in primary THA. MethodsFifty patients (61 hips) with THA for severe dysplastic osteoarthritis and a far proximal cup position were included. Patients were divided according to the heights of the implanted cups with increasing vertical distance from the interteardrop line (group A: 55-65 mm, group B: 65-75 mm, group C: >75 mm). Functional outcome was assessed at latest follow-up (38 ± 16 months) by Lower Extremity Functional Score, Tegner Activity Score, and Harris Hip Score (HHS). Patients answered a Patient Satisfaction Questionnaire. Leg length discrepancy was estimated radiographically. ResultsThe Lower Extremity Functional Score significantly decreased in C (45.3 ± 25) compared to A (66.7 ± 15.3) and B (67.9 ± 9.9). The Tegner Activity Score significantly increased in all subgroups from preoperative to postoperative (2.2 ± 1.3 to 4.1 ± 1.4; P < .05). The mean overall HHS was 89.3 ± 14.7 (A: 89.5 ± 14.3, B: 94.3 ± 6.5, C: 78.3 ± 22.1). The HHS domains of activity of daily life and gait were significantly reduced in C (P < .05). Patients described a high satisfaction level with the surgery. No significant differences were found with regard to preoperative and postoperative leg lengthening (P = .881). Neither dislocations, impingement problems nor neurologic complications were observed. ConclusionPrimary THA without any concomitant surgical interventions with a far proximal cup position offers a safe and effective treatment option in severe dysplastic hip osteoarthritis.

Dynamic femoral head translations in dysplastic hips

BackgroundDevelopmental dysplasia of the hip is an important disease leading to osteoarthritis. Recently, researchers have focused on hip instability as a potentially important dynamic factor for osteoarthritis, but the detailed kinematics of dysplastic hips during weight-bearing gait have not been reported. The purpose of this research is to contrast femoral translation in contralateral healthy hips and dysplastic hips during weight-bearing stepping. MethodsTwelve dysplastic hips and eight healthy hips were investigated. Hip joint kinematics were analyzed using 3D-2D model-image registration with dynamic fluoroscopic images of each hip during a stepping-in-place activity. Femoral translation relative to the acetabular center was quantified as instability. FindingsTotal femoral head translations were significantly different between dysplastic and contralateral healthy hips. Mean translation was 1.0mm in dysplastic hips and 0.4mm in contralateral healthy hips during swing-phase, and consisted of inferior translation during early swing phase with a complementary superior translation just before foot strike. Total femoral translation was significantly correlated to several radiographic indices of hip dysplasia. InterpretationSuperior translations of the femur during the end of swing phase may result in altered articular contact mechanics, abnormal stresses on the labrum and lost lubricant sealing. All of these factors may contribute to joint degeneration and osteoarthritis in dysplastic hips.

Anterior dominant joint space narrowing in the dysplastic hip osteoarthritis

Anterior dominant joint space narrowing in the dysplastic hip osteoarthritis

The role of femoral neck anteversion in the development of osteoarthritis in dysplastic hips.

There have been several studies examining the association between the morphological characteristics seen in acetabular dysplasia and the incidence of the osteoarthritis (OA). However, most studies focus mainly on acetabular morphological analysis, and few studies have scrutinised the effect of femoral morphology. In this study we enrolled 36 patients with bilateral acetabular dysplasia and early or mid-stage OA in one hip and no OA in the contralateral hip. CT scans were performed from the iliac crest to 2 cm inferior to the tibial tuberosity, and the morphological characteristics of both acetabulum and femur were studied. In addition, 200 hips in 100 healthy volunteer Chinese adults formed a control group. The results showed that the dysplastic group with OA had a significantly larger femoral neck anteversion and a significantly shorter abductor lever arm than both the dysplastic group without OA and the controls. Femoral neck anteversion had a significant negative correlation with the length of the abductor lever arm and we conclude that it may contribute to the development of OA in dysplastic hips.

Patient-specific analysis of cartilage and labrum mechanics in human hips with acetabular dysplasia

Acetabular dysplasia is a major predisposing factor for development of hip osteoarthritis (OA), and may result from alterations to chondrolabral loading. Subject-specific finite element (FE) modeling can be used to evaluate chondrolabral mechanics in the dysplastic hip, thereby providing insight into mechanics that precede OA. To evaluate chondrolabral contact mechanics and congruency in dysplastic hips and normal hips using a validated approach to subject-specific FE modeling. FE models of ten subjects with normal acetabula and ten subjects with dysplasia were constructed using a previously validated protocol. Labrum load support, and labrum and acetabular cartilage contact stress and contact area were compared between groups. Local congruency was determined at the articular surface for two simulated activities. The labrum in dysplastic hips supported 2.8-4.0 times more of the load transferred across the joint than in normal hips. Dysplastic hips did not have significantly different congruency in the primary load-bearing regions than normal hips, but were less congruent in some unloaded regions. Normal hips had larger cartilage contact stress than dysplastic hips in the few regions that had significant differences. The labrum in dysplastic hips has a far more significant role in hip mechanics than it does in normal hips. The dysplastic hip is neither less congruent than the normal hip, nor subjected to elevated cartilage contact stresses. This study supports the concept of an outside-in pathogenesis of OA in dysplastic hips and that the labrum in dysplastic hips should be preserved during surgery.

Accuracy of Cup Height and Medialization in THA for Dysplastic Hip Osteoarthritis Using an Imageless Navigation System

In total hip arthroplasty (THA) for dysplastic hip osteoarthritis, bony deformity makes it difficult to identify the correct cup height and medialization. The authors developed a new technique for registration and navigation of cup position for dysplastic hips using an imageless navigation system. Eighty dysplastic hips (Crowe type I, n=58; type II, n=18; type III, n=4) underwent THA. Thirty-four hips were operated on while in the supine position and 46 hips were operated on while in the lateral position. Before capsulectomy, the anterior pelvic plane and the position of the femur were registered. After exposure of the acetabulum, the teardrop, posterior rim, and medial wall of the acetabulum were registered. Then the cup height, cup medialization, cup inclination, anteversion, and leg lengthening were navigated. The difference between the navigated and radiographic cup heights was 4.5 ± 4.0 mm, the difference in cup medialization was 3.0 ± 2.5 mm, the difference in cup inclination was 4.3° ± 3.1°, the difference in cup anteversion was 5.5° ± 3.8°, and the difference in leg lengthening was 3.7 ± 3.0 mm. Comparison of the first 20 cases with the last 20 cases showed that the accuracy of cup medialization was significantly improved. These differences were not affected by Crowe type or surgical position. Because the correct cup height and medialization are key issues in THA for dysplastic hip osteoarthritis, the accuracy of cup height and medialization in this imageless navigation system were acceptable for clinical application.

Modified Metaphyseal‐Loading Anterolaterally Flared Anatomic Femoral Stem: Five‐ to Nine‐Year Prospective Follow‐Up Evaluation and Results of Three‐Dimensional Finite Element Analysis

We have designed a proximal-fitting, anterolaterally flared, arc-deposit hydroxyapatite-coated anatomical femoral stem (FMS-anatomic stem; KYOCERA Medical, Osaka, Japan) for cementless total hip arthroplasty (THA) for Japanese patients with dysplastic hip osteoarthritis, using a nonlinear three-dimensional finite element analysis simulating loading conditions. The Anatomic Fit stem was modified in the region of the arc-sprayed surface, to allow more proximal appearance of spot welds. The aim of the present study was to analyze the clinical and radiographic outcomes of patients who underwent THA using this stem. We reviewed 73 consecutive patients (79 hips; 13 men 16 hips; 60 women 63 hips; age at surgery, 57.6 years, range, 35-78) who underwent cementless THA using the Anatomic Fit stem, at a follow-up period of 7.1 years (range, 5.1-9.4). Harris Hip score improved from 40.7 ± 17.1 before surgery to 91.0 ± 5.2 points at follow-up. The 7.1-year stem survival rate was 100%. Radiographs at follow-up confirmed the stability of the femoral stems within the femoral canal in all cases, with sufficient bone ingrowth. None of the patients had subsidence of the stem exceeding 2.0 mm within the femoral canal or changes in varus or valgus position of more than 2.0°. The Anatomic Fit stem provided excellent results. The nonlinear three-dimensional finite element analysis demonstrated that the stem-bone relative motion was 10 µm at the proximal end of the stem and proximal load transfer. Our analysis confirmed reduced radiolucency around the stem, minimal subsidence, appropriate stress shielding, and promising medium-term stability within the femoral canal.

The Chiari pelvic osteotomy for patients with dysplastic hips and poor joint congruency

We report the mid- to long-term (mean 20.3 years, 10 to 32.5) results of the Chiari pelvic osteotomy in patients with pre- to advanced stage osteoarthritis in dysplastic hips. We followed 163 Japanese patients (173 hips) with a mean age at surgery of 20 years (9 to 54). Overall, 124 hips (72%) had satisfactory results, with Harris hip scores ≥ 80. Satisfactory results were seen in 105 of 134 hips with pre- or early osteoarthritis (78%) and 19 of 39 hips with advanced osteoarthritis (49%). A total of 15 hips (9%) underwent a total hip replacement (THR) with a mean interval between osteotomy and THR of 16.4 years. With conversion to THR as the endpoint, the 30-year survival rate was 85.9% (95% confidence interval 82.3 to 89.5). It was 91.8% for patients with pre- or early osteoarthritis and 43.6% for those with advanced osteoarthritis (p < 0.001). We now perform the Chiari osteotomy for patients with dysplastic hips showing poor joint congruency and who prefer a joint-conserving procedure to THR.

Results of Total Hip Arthroplasty with L-shaped Bone Grafting of the Femoral Head for Dysplastic Hip Osteoarthritis

Results of Total Hip Arthroplasty with L-shaped Bone Grafting of the Femoral Head for Dysplastic Hip Osteoarthritis

Metaphyseal-Loading Anterolaterally-Flared Femoral Stem in Cementless Total Hip Arthroplasty: Five- to Eleven-Year Follow-Up Evaluation

Using a nonlinear three-dimensional finite element analysis simulating loading conditions, we designed a new type of proximal-fitting, anterolaterally-flared, arc-deposit hydroxyapatite-coated anatomical femoral stem (FMS-anatomic stem; Japan Medical Materials, Osaka, Japan) for cementless total hip arthroplasty (THA) for Japanese patients with dysplastic hip osteoarthritis. The aim of the present study was to analyze the clinical and radiographic outcomes of the new stem. We reviewed 143 consecutive patients (164 hips; 13 men, 14 hips; 130 women, 150 hips; age at surgery, 56.6 +/- 7.6 years, mean +/- SD, range, 30-74) who underwent cementless THA using the FMS-anatomic stem at a single institution, with a follow-up period of 7.6 +/- 1.6 years (range, 5.3-11.0). Harris Hip score improved from 46.1 +/- 12.6 before surgery to 90.0 +/- 8.9 points post-THA. The 7.6-year survival rate of the stem was 99.0% after revision for aseptic loosening. Radiographs at follow-up confirmed the stability of the femoral stems within the femoral canal in all cases, with sufficient bone ingrowth. None of the patients had subsidence of the stem exceeding 2.0 mm within the femoral canal or changes in varus or valgus position of more than 2.0 degrees . The FMS-anatomic stem provided excellent results in patients with dysplastic hip osteoarthritis. Our analysis confirmed reduced radiolucency around the stem in Gruen zones, minimal subsidence, appropriate stress shielding, and promising medium-term stability within the femoral canal in our patients.

Intracapsular pressure and interleukin-1β cytokine in hips with acetabular dysplasia

Background and purpose Several studies have demonstrated an increased intracapsular pressure in several hip disorders such as septic arthritis, synovitis, and trauma. We therefore measured the intracapsular pressure in different positions in early dysplasic hips and its relation to the concentration of interleukin-1β (IL-1β), the volume of joint fluid, and the clinical and radiographic findings before a periacetabular osteotomy.Methods 12 female patients (12 hips, mean age 35 (18–52)) with hip dysplasia were investigated. The intracapsular pressure was recorded and we investigated possible correlations with the Harris hip score, the Tönnis scale, radiographic findings, the volume of joint fluid, and the concentration of IL-1β.Results An increased intracapsular pressure was noted, especially in flexion or extension with internal rotation. We found positive correlations between the intracapsular pressure and both the volume of joint fluid and the concentration of IL-1β.Interpretation Increased intracapsular pressure varied with different positions, indicating the presence of synovitis resulting from early osteoarthritis in dysplastic hips. Positive correlations between the pressure and both the concentration of IL-1β and the volume of joint fluid suggest that the inflammatory cytokines produced by the synovial membrane as a consequence of mechanical instability of the hip joint may be of importance for the initiation and/or development of osteoarthritis in dysplastic hips.

Radiographic and Patient Factors Associated with Pre-Radiographic Osteoarthritis in Hip Dysplasia

Hip dysplasia leads to abnormal loading of articular cartilage, which results in osteoarthritis. The purpose of this study was to investigate the anatomic and demographic factors associated with the early onset of osteoarthritis in dysplastic hips by utilizing the delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) index as a marker of the disease. Ninety-six symptomatic dysplastic hips in seventy-four patients were assessed with standard radiographs and a dGEMRIC scan. The lateral center-edge angle of Wiberg, the acetabular index of Tönnis, and the break in the Shenton line were measured on a standing anteroposterior radiograph. Anterior undercoverage was assessed by measuring the anterior center-edge angle on a Lequesne false-profile view. A labral tear was considered to be present when contrast agent was seen through the entire thickness of the labrum on magnetic resonance arthrography. Osteoarthritis was defined as a dGEMRIC value of <390 msec (two standard deviations below the dGEMRIC index in normal hips). The mean dGEMRIC index (and standard deviation) for this cohort (473 +/- 104 msec) was significantly lower than that of a morphologically normal hip (570 +/- 90 msec). The anterior center-edge angle, the joint space width, and the presence of a labral tear were all found to be associated with osteoarthritis in the univariate analysis. Multivariate analysis identified age, the anterior center-edge angle, and the presence of a labral tear as independent factors associated with osteoarthritis. A second model was fitted with omission of the anterior center-edge angle because the lateral and anterior center-edge angles were highly correlated and the lateral center-edge angle is a more common clinical measure. This model identified age, the lateral center-edge angle, and the presence of a labral tear as significant independent factors associated with osteoarthritis. As has been demonstrated in previous studies of the hip, this investigation showed osteoarthritis to be associated with increasing age and the severity of dysplasia, as demonstrated both by the Wiberg lateral center-edge angle and the Lequesne anterior center-edge angle. Additionally, we identified a labral tear as being a risk factor for osteoarthritis.