Mylène Jansen

48 Chapter 3 (confirmed by radiography). Full weight-bearing of the distracted joint was encouraged with the use of crutches if needed with springs in the device to ascertain sufficient synovial fluid dynamics. Patients got anticoagulants (subcutaneous low molecular weight heparin) during treatment time and antibiotics (flucloxacillin) in case of pin-tract skin infections. After 2 months (average 60 days, range 54–64 days) the pins and monotubes were removed under anesthesia and patients were discharged without imposed functional restrictions. Follow-up Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires and visual analogue scores (VAS) of pain were assessed at baseline and yearly thereafter. Structural outcome was assessed at baseline, 1, 2, 5, and 7 years’ follow-up using radiographs. MRI was performed pre- and 1-year post-treatment. Treatment ‘failure’ was defined as undergoing TKA in the subsequent years after KJD (these patients were not further followed), whereas survivors still had their native knee without additional surgery at 9 years. Clinical outcome The WOMAC questionnaire (version 3.0, normalized to a 100-point scale for total and subscales; “100” being the best score) was used as primary outcome parameter. The secondary clinical outcome parameter was the VAS pain score (0–100 mm; “0” meaning no pain). Structural outcome Radiographic analysis Standardized weight-bearing, semi-flexed, posterior-anterior radiographs were made and evaluated by use of knee images digital analysis (KIDA) software. 11 Analyses were performed by 1 experienced observer, blinded to acquisition order and patient characteristics. The minimum and mean joint space width (JSW) of the most affected compartment (MAC) are presented. Subchondral bone density was measured in the MAC of the tibia and femur averaged and expressed in mm aluminum equivalents (Al eq), using an aluminum step wedge as reference. Quantitative MRI analysis MRI scans were performed with the Eckstein protocol. 6,12 The mean cartilage thickness over the subchondral bone area and the percentage of denuded subchondral bone area were calculated at baseline and 1-year follow-up for the MAC. 7