Transient osteoporosis as a reversible subtype of osteonecrosis of the hipjoint

There is still controversy whether transient osteoporosis of the hip joint represents a distinct self-limiting disease, or reflects only an early, rev ersible subtype of non-traumatic osteonecrosis (ON). Transient osteoporosis has several synonyms: algodystrophy of the hip; transient marrow oedema; o r bone marrow oedema syndrome - BMOES. Clinical presentation of BMOES shows mechanical hip joint pain, ON risk factors, and a diffuse bone marrow oede ma in MR imaging. Histomorphological changes resemble early ON, but with di ffuse sufficient repair in BMOES and focal and insufficient repair only at the border of the necrotic lesion in ON. Therefore the clinical course and outcome are significant different, with restitution occurring in BMOES, whi le progressive destruction of the joint takes place in ON. So far, the pref erred treatment strategies are protected weight bearing for BMOES, but oper ative treatment for ON. In a prospective study of patients with BMOES, the clinical, radiographic, and MRI course of 43 hip joints after core decompre ssion treatment were investigated. All patients showed immediate relief of pain after surgery and the average duration of symptoms with conservative t reatment could be dramatically reduced by core decompression from 6 months down to 2 months. There were no perioperative complications. Based on our e xperience with over 100 BMOES patients,we are convinced that this syndrome represents not a distinct disease but an early reversible subtype of non-tr aumatic: ON. Due to the excellent clinical results of core decompression, w e recommend this operative therapeutical concept in patients with painful B MOES.