Thesis

101 SPECT/CT in post-operative hand and wrist pain Scaphoid fracture and nonunion Scaphoid fractures occur as a result of a fall on the outstretched arm. Because the blood supply of the bone is often impaired by the fracture there is a significant risk of osteonecrosis of the proximal pole (13-50%). Nonunions occur in 5-10% and progression to scaphoid nonunion advanced collapse (SNAC) may worsen the prognosis [10]. In case of nonunion different operative procedures can be used: in non-displaced stable nonunions without degenerative changes or necrosis nonvascularized bone grafts from the distal radius or iliac crest may be sufficient. In contrast, in presence of avascular proximal scaphoid pole vascularized bone grafts should be considered [11]. The advantage of vascularized bone grafting is the preservation of blood supply, primary bone healing and maintenance of structural integrity. In very advanced stages with severe OA different ways of midcarpal fusion are operative therapeutic options [12, 13]. CT is the imaging modality of choice if nonunion is suspected on conventional X-rays [14]. MR serves as the reference standard for the assessment of viability of the proximal scaphoid pole in nonunions with sensitivity, specificity and accuracy of 54-62%, 93%, and 75-78% in a series of 40 cases with histopathologic correlation, respectively [15, 16]. For the initial diagnosis of scaphoid fracture conventional bone scintigraphy (BS) performs slightly better than CT and MR: the sensitivity and specificity of CT were 72% and 99%; for MRI these were 88% and 100%; and for BS 99% and 86% in a meta-analysis [17]. Since SPECT/CT combines the morphologic information of CT and the metabolic information of conventional scintigraphy it showed slightly better performance for carpal fractures compared to MR [18]. Planar bone scintigraphy is able to show impaired perfusion of carpal bones as shown in patients with idiopathic necrosis [19]. Some case reports indicate the value of SPECT/CT as one-stop shop modality for the assessment of impaired perfusion of the lunate in Kienböck`s disease [20], but there is no literature regarding the performance of SPECT/CT in the assessment of scaphoid necrosis in nonunion. In our own experience SPECT/CT can serve as a promising alternative to MR and CT for the assessment of scaphoid nonunion and therapy planning. Decreased radionuclide uptake of scaphoid fragments, especially in the proximal pole with sclerosis on CT is a sign of malperfusion/osteonecrosis. Other important signs are missing fusion, integrity or displacement of the bone and OA accompanied by increased uptake of the bony borders. By adding inta-articular contrast, a technique previously described for the wrist, knee and ankle joint, the integrity of the cartilage and scapholunar or lunotriquetral ligaments can be evaluated [5, 6]. There is a wide range (30-100%) of published healing rates after treatment of scaphoid pseudarthrosis with bone grafts [11]. Complications might be infection, graft extrusion, graft resorption or progressive OA. SPECT/CT can be used to assess these kinds of therapy failures and to identify the pain generator. 4

RkJQdWJsaXNoZXIy MjY0ODMw