Purpose: In radiological assessment of hip osteoarthritis, minimal joint space width (mJSW) is widely used as a potent surrogate of disease progression. However, conventional, manual measurements of mJSW have limited sensitivity and reproducibility to assess subtle change of JSW for longitudinal observation of hip osteoarthrits. We have developed a computational program which allows automatic measurement of mJSW. The purpose of the present study was to investigate natural course of patients with hip osteoarthritis and to examine potential risk factors for progressive joint space narrowing. Methods: Fifty-three patients (73 hips) who consulted to our hospital in 1997-2000 and received annual examinations over 6 years without surgical intervention, were enrolled. There were 9 men and 44 women, and mean age was 48.8 years (range 21-73 years) at the initial examination. The initial radiograph showed Kellgren/Lawrence (K/L) grading of 1/2/3 in 23/36/14 hips, respectively. Mean duration of followup was 8.9 years (range 6-12 years) and anteroposterior pelvis radiographs were obtained annually. On a custom-made computational software, an operator manually identified the 5 seed points including bilateral tear drops, lateral rim and medial extreme of the acetabular roof, and approximate center of the femoral head. The, center edge (CE) angle, Sharp angle, center of the femoral head with respect to the tear drop, mJSW, and localized mJSW at the 3 equally subdivided locations (medial, intermediate, and lateral) of the weight-bearing were calculated automatically. We evaluated longitudinal change of mJSW of all patients and examined potential risk factors for progressive narrowing of mJSW, including CE angle, Sharp angle, initial K/L grading. Results: The initial average mJSW was 3.39±2.75mm, and localized medial/intermediate/lateral mJSW was 2.91±2.64mm/ 2.85±1.91mm/3.72±3.33mm, respectively. From overall patterns of progression of mJSW during followup, we divided the group into 2 subpopulations; progressive and non-progressive OA groups using the threshold of 1.0mm decline of mJSW during the fol-lowup. There were 34 hips in progressive OA group, and 39 hips in non-progressive OA group. In progressive OA group, 12/8/14 hips had most declined JSW at medial/intermediate/lateral location, respectively. There was a significant association between the intermediate/lateral mJSW decline at the last radiograph and initial Sharp angle (r=0.38/0.54, respectively), while there was not a significant association between K/L grading and the decline in mJSW. Conclusions: Radiographic hip mJSW was reliably quantified during longitudinal followup using a computational, automated software on standard radiographs. The results suggested that hip joint space measurement may be a practical and reliable method of assessing disease progression and detecting patient with high risk of subsequent progression of OA.
Shiomi, T., Nishii, T., Sakai, T., Takao, M., Hananouchi, T., Nakahara, I., … Sugano, N. (2009). 440 LONGITUDINAL ANALYSIS OF PROGRESSION IN HIP OSTEOARTHRITIS OVER 6 YEARS, USING A COMPUTATIONAL, AUTOMATED ALGORITHM. Osteoarthritis and Cartilage, 17, S234–S235. https://doi.org/10.1016/s1063-4584(09)60461-1