Introduction: The purpose of this study was to identify the diagnostic possibilities of the different diagnostic techniques in the evaluation of the pathological conditions affecting the peritalar region.
Materials and methods: Between September 1995 and December 1996, 58 patients, with a painful syndrome at peritalar level were submitted to MRI, which was performed using a 'dedicated system' consisting of 0.2 and 0.5 T equipment. Spin-Echo T1-weighted and Gradient-Echo T2-weighted sequences were used on sagittal, coronal and axial planes, with slice thickness of 3-5 mm. Conventional radiography was previously performed in all patients, while 18 of them underwent CT. Surgery or arthroscopy was performed in 22 cases. 36 patients underwent clinical follow-up associated with conventional radiography in six cases, MRI in 11 and to both of them in six patients.
Results: After arthroscopy and surgery, an involvement of the tibio-talar joint was found (one pathogenic synovial plica, three meniscoid syndrome and 12 anterior impingement) in 16 patients. Concerning the subtalar joint, surgical examination revealed a cellulo-adipostis of the sinus tarsi in two patients, while in three cases osteochondral damage of the subtalar joint was identified. In the last patient, degenerative changes of the posterior tibial tendon associated with osteochondral pathology of the talo-navicular joint were found. MRI findings agreed with the surgical and arthroscopic ones in all patients except for the synovial plica; in this case, the MRI was negative. Follow-up performed on 36 patients revealed 12 tibio-talar joint, 17 subtalar joint and 7 talo-navicular joint pathological conditions.
Discussion: Concerning the tibio-talar joint, MRI findings were confirmed by arthroscopy in all cases of anterior impingement. Magnetic resonance (MR), due to its capability in detecting osteochondral damage and identifying osteophyte sites, results in the best imaging method for evaluating this condition. Meniscoid syndrome is easily detected by MRI only in the presence of sufficient scar tissue, while conventional radiography reveals the calcific stage. In sinus tarsi syndrome, the ligamentous damage associated with sero-hemorrhagic effusion at fatty tissue level may lead to a 'chopping' effect on the nerve endings: this condition is well demonstrated by MRI. In all cases of osteochondral alterations affecting both the subtalar and talo-navicular joint, it has been possible to obtain correct diagnosis with MRI, which also depicted well the tenosynovitis of the posterior tibial tendon. In cases of stress fracture of the navicular bone, both CT and MRI demonstrated the lesions well, even when, in the early phases, conventional radiography produced a negative result. In conclusion, MRI may be considered the choice method in the study of different pathological alterations affecting the peritalar region, also providing detailed information useful for a therapeutic approach.