Radiography and bone scintigraphy in osteoarthritis of the knee: comparison with MR imaging

The aim was to compare radiography of the tibiofemoral joint (TFJ) and the patellofemoral joint (PFJ), as well as bone scinigraphy with MR imaging in middle-aged individuals with chronic knee pain in the format of a prospective study of knee osteoarthritis. Individuals aged 35-54 years with chronic knee pain were identified. The prevalence of chronic knee pain was 15% (279/2000). Within this group of people, both knees in 61 randomly chosen persons, were examined with plain weight-bearing radiograms of the TFJ, standing axial radiograms of the PFJ and bone scintigraphy. One knee (the most painful at inclusion in the study) in each person was examined with MR imaging on a 1.0 T imager. Assessment of the minimal joint space (MJS) width in the PA view of the TFJ in weight-bearing examinations should be performed with equal weight on both legs and in semiflexion. MJS of 3 mm in the TFJ and MJS of 5 mm in the PFJ are limits in diagnosing joint-space narrowing (JSN) in the TFJ and the PFJ, respectively. There is a high prevalence of meniscal abnormalities within the narrowed compartments of the TFJ in comparison with those that were narrowed. With the presence of marginal osteophytes in the TFJ there is a high prevalence of MR-detected cartilage defects in the same joint whether JSN (MJS < 3 mm) is present or not. No such relationship, independent of MJS, was found between marginal osteophytes and cartilage defects in the PFJ. The agreement between increased bone uptake and MR-detected subchondral lesion was good. The agreement between increased bone uptake and MR-detected osteophytes or cartilage defects was in general poor. With the increased knowledge about interpreting weight-bearing PA radiograms of the TFJ and axial radiograms of the PFJ, these examinations will even in the future be valuable when evaluating knee pain. Further studies have to be done to evaluate if MR imaging has the same ability as bone scintigraphy to predict the progression of the OA process