Aims: To clarify correlation between magnetic resonance imaging (MRI) and pathology of pain in posterior aspect of the ankle in ballet dancers. Methods: Twenty feet of þfteen patients, who underwent surgery with the average age of 19.2 years, were retrospectively analyzed. They were diagnosed as ßexor hallucis longus (FHL) tendon injury or posterior ankle impingement (PAI) syndrome mainly based on physical signs. MRI þndings of FHL tendon were classiþed with the classiþcation of posterior tibial tendon dysfunction presented by Conti et al., and were compared with macroscopic changes of the tendon. FHL injuries were classiþed as follows; paratendinitis as grade-1, superþcial injury (< 1/2 thickness) as grade-2, and deep injury as grade-3. MRI þndings of PAI syndrome were also compared to surgical and histological þndings. Results: Correlation of FHL tendon injury with MRI þndings was presented on the table. There was a case with a ganglion cyst of FHL tendon presented on MRI. There were, however, two cases with ganglions on þbro-osseous tunnel MRI could not reveal. In four feet of three patients, bone marrow edema in os trigonum or posterior part of the talus was observed. Conclusion: MRI was useful to investigate the pathology of pain in posterior aspect of the ankle.

Using in situ hybridisation and the terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick end-labelling (TUNEL) reaction in rats with osteonecrosis of the femoral head we have studied the effect of ischaemia on the gene expression of the stress proteins oxygen-regulated protein 150 (ORP150) and haemoxygenase 1 (HO1) and the death mechanism of the cells involved in osteonecrosis. Both ORP150 and HO1 have been reported to have important roles in the successful adaptation to oxygen deprivation.

ORP150 and HO1 mRNA expression was induced by ischaemia in osteoblasts and osteocytes. In proliferative chondrocytes, these signals were detected constitutively. During the development of ischaemic osteonecrosis, the mechanism of cell death was apoptosis as indicated by DNA fragmentation and the presence of apoptotic bodies in osteocytes, chondrocytes and bone-marrow cells. After the initial ischaemic event, expression of ORP150 and HO1 mRNA, the TUNEL-positive reaction and empty lacunae were found sequentially. These findings were exclusive and may be considered to be markers for each stage in the development of osteonecrosis.