Clinical outcome of rearthrodesis in cases of non-union following four-corner fusion

Purpose Four-corner fusion is a proven treatment option for degenerative arthritis of the wrist (SLAC/SNAC); however, in some cases, non-union occurs. The purpose of this study was to evaluate the clinical outcome of rearthrodesis in cases of non-union following four-corner fusion. Furthermore, the goal was to identify the cause of non-union and the location of pseudarthrosis within the fusion. Methods Seven patients (5 males, 2 females) who experienced pseudarthrosis following a four-corner fusion procedure and subsequently elected a rearthrodesis procedure were clinically and radiologically examined. The average age was 58 years (range 48–71 years). Average follow-up after rearthrodesis was 27 months (range 4–60 months). All patients experienced persistent wrist pain and non-union was diagnosed via radiography or CT scan. Range of motion, grip strength, the Modified Mayo Wrist score, and the DASH score were evaluated. The level of pain was determined by using a visual analogue scale. Patients were also asked whether they were satisfied with the procedure and if they would elect it again. Results In all patients, the rearthrodesis procedure led to proper bone consolidation, which was verified by radiological examination. Due to persistent wrist pain, one patient required additional procedures (denervation, wrist arthroscopy). In four cases, the location of pseudarthrosis occurred between the triquetrum and hamate. In three cases, the location of pseudoarthrosis was between the capitate and lunate and, additionally, between the triquetrum and hamate. The average DASH score value was 38 and the average Modified Mayo Wrist score was 66. Grip strength was reduced to 85 percent of the contralateral, unaffected side. Three patients indicated that they are dissatisfied with the results and would not elect the procedure again. Conclusions The most frequent location of pseudarthrosis was between the triquetrum and the hamate, which was caused by incomplete cartilage debridement. Proper bone consolidation could be attained by means of rearthrodesis in cases of non-union following four-corner fusion. However, clinical results remain only moderate.