104 Part I Chapter 4 Pain reduction and preservation of non-affected joint lines are the aim of surgery. Because of the large movement amplitude and small bony contact zone, the fusion rate of partial arthrodesis of the wrist is lower compared with large joints. Especially fusion of a single joint like the lunotriquetral joint is difficult [26]. For successful fusion the complete resection of the cartilage and subchondral bone, compression and fixation of bone parts is necessary, for which fusion plates and wires are used. For mediocarpal arthrodesis fusion between various carpal bones with resection of the scaphoid is performed in patients with painful OA between scaphoid and radius. Often a tear of the scapholunar ligament is the underlying cause or a pseudarthrosis after scaphoid fracture with OA [27]. Complications of this procedure can be: pseudarthrosis, an impingement of the capitate against the posterior radius in wrist extension, and extensor tendon injuries caused bymovingwires and adjacent OA. The aim of scaphoid-trapezium-trapezoid (STT) fusion is stabilization of the radial column and is performed in STT OA and lunatum osteonecrosis. The main complication of STT arthrodesis is nonunion with a rate of up to 29% [28]. Other complications are adjacent OA and impingement against the styloid process. The radioscapholunar (RSL) arthrodesis is the union of the radiocarpal joint in patients with painful OA of the radiocarpal joint, often after intraarticular distal radius fracture. The nonunion rate in RSL arthrodesis was reported to be up to 27% in the past, but the outcome has significantly improved if additional distal scaphoidectomy is performed [29, 30]. The lunotriquetral (LT) arthrodesis is rarely performed in patients with painful LT ligament instability or localized OA and is associated with a high nonunion rate of 27% [31]. The complete wrist arthrodesis encompasses the fusion of the radiocarpal and midcarpal joint and serves as last option if motion-preserving procedures are no longer possible (Figure 4). Complications are nonunion and loosening or fracture of the plate. SPECT/CT can be used to assess the typical complications of wrist partial or complete arthrodesis by showing absent fusion on CT associated with increased uptake in nonunion, OA with joint space narrowing and subchondral cysts and sclerosis together with increased uptake in adjacent OA and increased bone uptake in impingement. Wrist arthroplasties Wrist and finger joint arthroplasties might be a therapeutic option in severely destroyed and painful joints in OA, trauma or rheumatologic diseases and if arthrodesis should be avoided to preserve joint motion. Total wrist arthroplasty is very rarely performed. More often arthroplasty of the distal radioulnar joint (DRUJ) (Figure 5) is performed with replacement of the ulnar head or evenmulti-component implants, consisting of a radial component replacing the sigmoid notch and an ulna component replacing the ulna head [32].