Introduction: The cup and cone technique, first described by Carrol and Hill is very simple. It affords excellent contact between bones, and allows all possible adjustments of the arthrodesis in three planes before its final fixation.
Material and methods: Fifty seven cup and cone arthrodesis of the thumb were performed in 41 adult tetraplegic patients. Level of arthrodesis was i.p. in 28 cases, TM in 25 cases and MP in 4 cases. Distribution in Giens classification was 3 group 1, 14 group 2, 9 group 3, 23 group 5, 2 group 6, 1 group 7, 2 group 10. Mean follow-up was 51 months. Three criteria were retrospectively studied: the clinical strength of arthrodesis, its position, and the potential existence of complications.
Results: Clinical fusion was obtained in 8 week in all cases, without any infection. No delayed union was observed. In only one case, a surgical revision was required, due to initial bad setting of TM arthrodesis and an intermetacarpal arthrodesis was performed with a bony graft. In all other cases, position of arthrodesis was correct. In a few cases, only minor or non specific drawbacks were observed: TM arthrodesis were sometimes painful during the first 6 months postoperatively; transient dystrophy of the thumb nail occurred two times in i.p. arthrodesis; the worst drawback was the shortening of the thumb, which impaired the key-grip in cases where the thumb was preoperatively short.
Discussion: In tetraplegic patients, stabilization of the thumb can be obtained either by split distal FPL tenodesis or by an arthrodesis at TM, MP or i.p. level of the thumb. When the provided thumb length is adequate arthrodesis is preferred. The cup and cone technique is very simple and effective. It is fit particularly in tertraplegic patients, whatever the level of the thumb arthrodesis.