Objective
To study the association between various radiographic definitions of acetabular dysplasia (AD) and incident radiographic hip osteoarthritis (RHOA), and to analyze in subgroups.

Methods
Hips free of RHOA at baseline and with follow-up within 4–8 years were drawn from the World COACH consortium. The Wiberg center edge angle (WCEA), acetabular depth width ratio (ADR), and the modified acetabular index (mAI) were calculated. AD was defined as WCEA≤25°, and for secondary analyses as WCEA≤20°, ADR ≤250, mAI ≥ 13°, and a combination. A logistic regression model with generalized mixed effects with 3 levels adjusted for age, biological sex, and body mass index (BMI) was used. Descriptive statistics stratified by age, biological sex and BMI were reported.

Results
A total of 18,807 hips from 9 studies were included. Baseline characteristics: age 61.84 (± 8.32) years, BMI 27.40 (± 4.49) kg/m², 70.1% women. 4766 hips (25.3%) had WCEA≤25°. Within 4–8 years (mean 5.8 ±1.6) follow-up, 378 hips (2.0%) developed incident RHOA. We found an association between AD and RHOA (adjusted OR [aOR] 1.80 95% confidence interval [CI] 1.40–2.34). In secondary analyses, all other definitions of AD were also associated with incident RHOA (aOR ranging from 1.52 95% CI 1.19–1.94 to 1.96 95% CI 1.26–3.02). Descriptive statistics showed that the relative risk (RR) in AD hips to develop RHOA was higher compared to non-AD hips in age group 61–70 (RR 1.70), BMI<25 (RR 1.66), and in female hips (RR 1.73).

Conclusion
AD was consistently associated with incident RHOA. Explorative analyses show that AD hips in women and age group 61–70 years seem to be more at risk of developing RHOA compared to non-AD hips.@en

Objective: The objective is to determine the association and absolute risk of femoroacetabular impingement syndrome (FAIS) for the development of radiographic hip osteoarthritis (RHOA). Methods: This is a nationwide, multicentre prospective cohort study (Cohort Hip and Cohort Knee) with 1002 individuals aged between 45 and 65 years. Hips without definitive RHOA (Kellgren-Lawrence (KL) grade≤1) at baseline and with anteroposterior pelvic radiographs at baseline and 10-year follow-up available (n=1386 hips) were included. FAIS was defined by the baseline presence of a painful hip, limited internal hip rotation≤25° and cam morphology defined by an alpha angle>60°. The outcomes were incident RHOA (KL grade≥2 or total hip replacement (THR)) and incident end-stage RHOA (KL≥3 or THR) within 10 years. Results: Of the 1386 included hips (80% women; mean age 55.7±5.2 years), 21 hips fulfilled criteria for FAIS and 563 hips did not fulfil any of the FAIS criteria (reference group; no symptoms, no signs, no cam morphology). Within 10-year follow-up, 221 hips (38%) developed incident RHOA and 15 hips (3%) developed end-stage RHOA (including 9 hips with THR). Adjusted for sex, age and body mass index, FAIS with cam morphology resulted in an OR of 6.85 (95% CI 2.10 to 22.35) for incident RHOA and 47.82 (95% CI 12.51 to 182.76) for incident end-stage RHOA, compared with hips not having any FAIS criteria. The absolute risk of FAIS was 81% for incident RHOA and 33% for incident end-stage RHOA. Conclusion: FAIS was strongly associated with the development of RHOA within 10 years. Although the baseline prevalence of FAIS was low, the high absolute risk of FAIS for RHOA warrants further studies to determine preventive strategies.

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Objective: To examine the association between 3D patellar shape and 1) isolated magnetic resonance imaging (MRI)-based patellofemoral osteoarthritis (PFOA), 2) the morphological features of PFOA, and 3) the clinical symptoms of PFOA. Design: MRI data from 66 women with isolated MRI-based PFOA and 66 age- and BMI-matched healthy women were selected from a cohort study. The patellae were manually segmented from MRI scans and used to create a 3D statistical shape model (SSM) of the patella. Structural abnormalities were semi-standardized scored on MRI using MRI osteoarthritis knee score (MOAKS). Regression analyses were applied to determine the associations between the shape parameters retrieved from the SSM, group status, clinical symptoms, and structural abnormalities. Results: Four shape variants showed a statistically significant (<0.05) association with the group status. The mode responsible for most of the shape variations showed participants with PFOA possess a relatively thicker dorsal bump on the articular part of the patella, compared to patellae of control participants. Three of these variants showed an association with the presence of osteophytes and cartilage loss on the patella. Multiple associations were found between patellar shape and the clinical symptoms of PFOA. Conclusions: Patellar shape is associated with the prevalence of MRI-based PFOA in women. Some shape variants were also associated with clinical symptoms. Interestingly, one particular shape variant associated with the presence of MRI-based PFOA was earlier shown to be associated with structural abnormalities associated with OA in a population aged under 40. This may suggest that patellar shape may be an early detectable risk factor for PFOA.

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Objective: To summarize available evidence on the association between hip shape as quantified by statistical shape modeling (SSM) and the incidence or progression of hip osteoarthritis. Design: We conducted a systematic search of five electronic databases, based on a registered protocol (available: PROSPERO CRD42020145411). Articles presenting original data on the longitudinal relationship between radiographic hip shape (quantified by SSM) and hip OA were eligible. Quantitative meta-analysis was precluded because of the use of different SSM models across studies. We used the Newcastle–Ottawa Scale (NOS) for risk of bias assessment. Results: Nine studies (6,483 hips analyzed with SSM) were included in this review. The SSM models used to describe hip shape ranged from 16 points on the femoral head to 85 points on the proximal femur and hemipelvis. Multiple hip shape features and combinations thereof were associated with incident or progressive hip OA. Shape variants that seemed to be consistently associated with hip OA across studies were acetabular dysplasia, cam morphology, and deviations in acetabular version (either excessive anteversion or retroversion). Conclusions: Various radiographic, SSM-defined hip shape features are associated with hip OA. Some hip shape features only seem to increase the risk for hip OA when combined together. The heterogeneity of the used SSM models across studies precludes the estimation of pooled effect sizes. Further studies using the same SSM model and definition of hip OA are needed to allow for the comparison of outcomes across studies, and to validate the found associations.

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Background: Altered perfusion might play an important role in the pathophysiology of patellofemoral pain (PFP), a common knee complaint with unclear pathophysiology. Purpose: To investigate differences in dynamic contrast-enhanced (DCE)-MRI perfusion parameters between patients with PFP and healthy control subjects. Population/Subjects/Phantom/Specimen/Animal Model: Thirty-five adult patients with PFP and 44 healthy adult control subjects. Field Strength/Sequence: 3T DCE-MRI consisting of a sagittal, anterior-posterior, frequency-encoded, fat-suppressed 3D spoiled gradient-echo sequence with intravenous contrast administration. Assessment: Patellar bone volumes of interest (VOIs) were delineated by a blinded observer. Quantitative perfusion parameters (k_ep and k_trans) were calculated from motion-compensated DCE-MRI data by fitting Tofts' model. Weighted mean and unweighted median values of k_ep and k_trans were computed within the patellar bone VOIs. Statistical Tests: Differences in patellar bone perfusion parameters were compared between groups by linear regression analyses, adjusted for confounders. Results: Mean differences of weighted mean and unweighted median were 0.0039 (95% confidence interval [CI] –0.0013; 0.0091) and 0.0052 (95% CI –0.0078; 0.018) for k_trans, and 0.046 (95% CI –0.021; 0.11) and 0.069 (95% CI –0.017; 0.15) for k_ep, respectively. All perfusion parameters were not significantly different between groups (P-values: 0.32; 0.47 for k_trans, and 0.24; 0.15) for k_ep. However, a significant difference in variance between populations was observed for k_trans (P-value 0.007). Data Conclusion: Higher patellar bone perfusion parameters were found in patients with PFP when compared to healthy control subjects, but these differences were not statistically significant. This result, and the observed significant difference in k_trans variance, warrant further research. Level of Evidence: 1. Technical Efficacy: Stage 3. J. Magn. Reson. Imaging 2018;47:1344–1350.

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