[Four-Corner Arthrodesis of the Wrist with Dorsal Circular Plate - a Retrospective Monocentric Study].

PURPOSE OF THE STUDY Our study aimed to evaluate a group of patients who in the period from 2005 to 2014 underwent a four-corner arthrodesis of the wrist in our department. We also wanted to verify the hypothesis as to whether the use of conventional dorsal plate without the application of bone grafts leads to comparable results as the use of dorsal locking plates and routine application of bone grafts. MATERIAL AND METHODS Throughout the years 2005 to 2014 the four-corner arthrodesis of the wrist was performed in our department in a total of 62 patients, in two cases bilaterally. The indication was the diagnosis of SLAC/SNAC grade III. Normed RondoFix implant was used in all the cases. Following the surgery, the wrist was immobilized by a volar plaster splint for the period of 2 weeks and subsequently orthosis was applied for additional 4 weeks. The wrist mobilisation started in week seven when the orthosis was removed, the patients were allowed full load on the wrist 3 months after the surgery. Our group of patients was evaluated retrospectively, a total of 53 operated wrists in 51 patients were assessed. The assessment was carried out based on a radiograph of the wrist, range of motion, Mayo Modified Wrist Score, DASH Score and grip strength test. RESULTS The mean range of motion in sagittal plane was 63.7°, in frontal plane the mean value was 32.1°. According to the Mayo Modified Wrist Score 37 patients were rated "excellent" or "good". Due to the presence of moderate pain, the result in other 10 patients was assessed as "satisfactory". In a total of 4 patients the result was assessed as "weak", in two of them for a presence of non-union and in other two for severe pain under load. One of these patients underwent bilateral surgery and reported severe pain in both the wrists. Regarding DASH score, the best result equalled 0, the worst 65.83, with the mean of 20.5. The grip strength ranged from 8 to 54 kg, with the mean value of 27.5 kg. In two patients, a non-union occurred. In the first case the extraction of implant and re-arthrodesis was performed due to severe pain and screw migration. The patient is now 22 months after the surgery and the radiographs show that the arthrodesis has healed and the patient has no clinical difficulties. The second patient did not report any difficulties, therefore he is only subject to follow-up. No cases of screw or plate breakage were reported. In one case, the patient reported pain in the region of radial styloid process. A revision was indicated with radial styloidectomy and decompression of tendons of m. extensor pollicis brevis and m. abductor pollicis longus. As a result the patient had no clinical difficulty. One case of wrist radial deviation was recorded. It was managed by corrective wedge osteotomy and reosteosynthesis using a circular dorsal plate. In one patient dorsal impingement occurred, accompanied by limited range of motion and pain. Extraction of OS material was indicated and the patient was relieved of any difficulties. We have recorded aseptic necrosis of lunate bone in one case. DISCUSSION When comparing the functional results such as the range of motion and grip strength, our results are fully comparable to previously published papers. In papers where DASH was referred to, its value ranges from 13 to 29.82, which is fully consistent with our observations with the final value of 20.5. The incidence of non-union and the degree of complications is not deviating from the values included in other publications either. In all the mentioned publications the authors refer to routine use of bone grafts. The publications evaluating the use of locking plates do not report different results either. CONCLUSIONS In case of correct indication, the four-corner arthrodesis of the wrist represents a very good solution. In our group of patients, we confirmed the hypothesis that equally good results as with the use of locking plates can be achieved when using a non-locking plate system. Essential is the proper correction of DISI and primary good congruence between fused carpal bones instead of the use of bone grafts. Key words: SLAC wrist, SNAC wrist, four-corner arthrodesis, partial wrist fusion.