MRI FOLLOW-UP OF PISIFORM BONE TRANSPOSITION FOR TREATMENT OF LUNATOMALACIA

Objective. Transposition of the pisiform bone is an operative treatmen t for lunatomalacia. The postoperative viability of the transposed pis iform bone is difficult to assess, The purpose of the study was to eva luate the utility of MRI for postoperative assessment of viability of the pisiform and lunate bones. Design and patients. Six patients who u nderwent transposition of the pisiform for treatment of lunatomalacia, were assessed pre-and postoperatively with conventional radiographs ( including tomography), CT and MRI. Results. Conventional radiographs, conventional tomograms and CT were all useful in demonstrating the loc ation of the transposed pisiform. CT showed the transposed pisiform wi thout superposition, However, neither CT nor conventional techniques p rovided information regarding viability of the pisiform. In all patien ts investigated in the first year following surgery, T1-weighted MR im ages showed high signal intensity in the transposed bones. In all pati ents investigated after 1 year, the signal intensity decreased to an i ntermediate level on T1-weighted images. Enhancement following contras t medium administration in the transposed pisiform and the lunate was noted in all patients, indicative of viability. Conclusion. Contrast-e nhanced MRI is able to provide important information regarding the via bility of the transposed pisiform and the remaining parts of the lunat e. Thus, contrast enhanced MRI provides an improved means of postopera tive assessment regarding short-term follow-up following pisiform tran sposition. In the long-term follow-up conventional radiography and CT may be equal to MRI in showing increasing sclerosis and/or fragmentati on.