Objective: To investigate the relationship between body mass index (BMI) and the incidence and progression of radiological knee as well as of radiological hip osteoarthritis. Design: Cohort study. Setting: Population based. Participants: 3585 people aged ⩾55 years were selected from the Rotterdam Study, on the basis of the availability of radiographs of baseline and follow-up. Main outcome measures: Incidence of knee or hip osteoarthritis was defined as minimally grade 2 at follow-up and grade 0 or 1 at baseline. The progression of osteoarthritis was defined as a decrease in joint space width. Methods:x Rays of the knee and hip at baseline and follow-up (mean follow-up of 6.6 years) were evaluated. BMI was measured at baseline. Results: A high BMI (>27 kg/m²) at baseline was associated with incident knee osteoarthritis (odds ratio (OR) 3.3), but not with incident hip osteoarthritis. A high BMI was also associated with progression of knee osteoarthritis (OR 3.2). For the hip, a significant association between progression of osteoarthritis and BMI was not found. Conclusion: On the basis of these results, we conclude that BMI is associated with the incidence and progression of knee osteoarthritis. Furthermore, it seems that BMI is not associated with the incidence and progression of hip osteoarthritis.

The Knee Injury and Osteoarthritis Outcome Score (KOOS) was constructed in Sweden. This questionnaire has proved to be valid for several orthopedic interventions of the knee. It has been formally translated and validated in several languages, but not yet in Dutch. The purpose of the present study was to evaluate the clinimetric properties of the Dutch version of the KOOS questionnaire in knee patients with various stages of osteoarthritis (OA).

Objective: To investigate the association between acetabular dysplasia and the incidence of radiographic osteoarthritis (OA) of the hip in a population‐based sample of elderly subjects.Methods: Radiographs of the hip at baseline and at followup (mean followup time 6.6 years) were evaluated in 835 men and women (age ≥55 years) from the Rotterdam Study. Subjects with a baseline Kellgren/Lawrence grade of 0 or 1 in both hips were included in the study. Incident radiographic OA of the hip was defined as a decrease of joint space width of the hip (≥1.0 mm) at followup. Acetabular dysplasia was assessed using the center‐edge angle and the acetabular depth. The association between acetabular dysplasia and incident radiographic hip OA was assessed by calculating odds ratios using multivariate regression analysis.Results: In this study population with a mean ± SD age of 65.6 ± 6.5 years, 9.3% developed incident radiographic hip OA. Subjects with acetabular dysplasia (center‐edge angle <25°) had a 4.3‐fold increased risk for incident radiographic OA of the hip (95% confidence interval 2.2–8.7) compared with subjects without acetabular dysplasia. These associations were independent of known determinants of hip OA such as age, sex, and body mass index (BMI), but tended to be enhanced by female sex, heavy mechanical load, and low BMI.Conclusion: In a study population age ≥55 years, acetabular dysplasia is still a strong independent determinant of incident radiographic hip OA.

Objective: To assess whether a clinically relevant difference exists in patients’ perceptions of symptoms, knee function, and ability to participate in sports over a period of two years after rupture of the anterior cruciate ligament (ACL) between two commonly used treatment regimens. Design: Open labelled, multicentre, parallel randomised controlled trial (COMPARE). Setting: Six hospitals in the Netherlands, between May 2011 and April 2016. Participants: Patients aged 18 to 65 with an acute rupture of the ACL, recruited from six hospitals. Patients were evaluated at three, six, nine, 12, and 24 months. Interventions: 85 patients were randomised to early ACL reconstruction and 82 to rehabilitation followed by optional delayed ACL reconstruction after a three month period (primary non-operative treatment). Main outcomes: Patients’ perceptions of symptoms, knee function, and ability to participate in sporting activities were assessed with the International Knee Documentation Committee score (optimum score 100) at each time point over 24 months. Results: Between May 2011 and April 2016, 167 patients were enrolled in the study and randomised to one of two treatments (mean age 31.3; 67 (40.%) women), and 163 (98%) completed the trial. In the rehabilitation and optional delayed ACL reconstruction group, 41 (50%) patients underwent reconstruction during follow-up. After 24 months, the early ACL reconstruction group had a significantly better (P=0.026) but not clinically relevant International Knee Documentation Committee score (84.7 v 79.4 (difference between groups 5.3, 95% confidence interval 0.6 to 9.9). After three months of follow-up, the International Knee Documentation Committee score was significantly better (P=0.002) for the rehabilitation and optional delayed ACL reconstruction group (difference between groups −9.3, −14.6 to −4.0). After nine months of follow-up, the difference in the International Knee Documentation Committee score changed in favour of the early ACL reconstruction group. After 12 months, differences between the groups were smaller. In the early ACL reconstruction group, four re-ruptures and three ruptures of the contralateral ACL occurred during follow-up versus two re-ruptures and one rupture of the contralateral ACL in the rehabilitation and optional delayed ACL reconstruction group. Conclusions: In patients with acute rupture of the ACL, those who underwent early surgical reconstruction, compared with rehabilitation followed by elective surgical reconstruction, had improved perceptions of symptoms, knee function, and ability to participate in sports at the two year follow-up. This finding was significant (P=0.026) but the clinical importance is unclear. Interpretation of the results of the study should consider that 50% of the patients randomised to the rehabilitation group did not need surgical reconstruction. Trial registration: Netherlands Trial Register NL 2618.