CHRONIC COMPLICATED OSTEOMYELITIS OF THE APPENDICULAR SKELETON - DIAGNOSIS WITH TC-99M LABELED MONOCLONAL ANTIGRANULOCYTE ANTIBODY-IMMUNOSCINTIGRAPHY

Chronic post-traumatic osteomyelitis (OM) represents a particular chal lenge for nuclear medicine and radiology since clinical and biochemica l parameters are frequently unreliable. The aim of this study was to i nvestigate the value of combined bone scan (BS) and immunoscintigraphy (IS) with technetium-99m labelled monoclonal antigranulocyte antibody (MAB) in patients with suspected chronic OM of the appendicular skele ton, Twenty-four patients (17 females and 7 males) with suspected chro nic post-traumatic OM were evaluated with three-phase BS/Tc-99m-MAB-IS . The final diagnosis was established by means of bone culture and his tology in 19 cases and clinical follow-up in five cases, The studies w ere reviewed by two independent and experienced observers; the interob server agreement was calculated by kappa statistics. The sensitivity, specificity and accuracy of BS alone were 92%, 18% and 58%, respective ly, Combined BS/(99)mTc-MAB-IS had a sensitivity, specificity and accu racy of 84%, 72% and 79%, respectively. Of 24 studies, 11 were true-po sitive, two false-negative, eight true-negative and three false-positi ve. Two patients presented with unexpected ectopic haematopoietic bone marrow in the appendicular skeleton that caused false-positive result s. A high degree of interobserver agreement was found (kappa=0.85). It is concluded that combined BS/(99)mTc-MAB-IS represents a very sensit ive and reproducible method with an acceptable specificity for the inv estigation of chronic OM, Problems may occur in the differentiation of low-grade OM from aseptic inflammation, Another problem is ectopic ma rrow that may occur in the appendicular skeleton due to a chronic infl ammatory stimulus. A former intramedullary intervention in the femur w ith displacement of haematopoietic marrow may also lead to an ectopic location.