[Experiences with the STT (scapho-trapezio-trapezoid) arthrodesis. A retrospective evaluation]

From 1992 until 1998, 98 fusions of the scapho-trapezio-trapezoid joint on 97 patients were performed in our clinic. The indications were dissociation of the scapho-lunate joint (n = 32), necrosis of the lunate stage III/IV (Lichtman classification) (n = 39), and idiopathic arthrosis of the scapho-trapezio-trapezoid joint (n = 27). 87 patients with 88 procedures were reviewed after an average follow-up period of three years. The review included a clinical examination with determination of a traditional wrist-score and a DASH questionnaire, X-rays of the wrist and CT of the carpal bones. The results in the wristscore were on average 74 of maximal 100 points. The DASH-score was on average 29. The best results were in the group with arthrosis of the scapho-trapezio-trapezoid joint. The results in the groups with scapho-lunate dissociation and necrosis of the lunate were also good. The rate of non-union was within an acceptable level with 7.7%. In the examined group, five patients underwent fusion of the wrist for persisting pain after scapho-trapezio-trapezoid arthrodesis. The examination of the radiological investigations in the reviewed group demonstrated, that CT shows arthritic degeneration in patients where the conventional X-ray does not. In conclusion, scapho-trapezio-trapezoid arthrodesis is a valid therapeutic method in the above mentioned indications. However, the question how early arthritic degeneration will affect long-term results remains unanswered for the moment.