A Modified Anatomic Front and Back (ANAFAB) Approach in a Case of Chronic Neglected Lunate Dislocation

The treatment of neglected chronic lunate dislocations is controversial while open reduction of lunate was often not available in the situation. Lunate excision, partial wrist fusion or proximal-row carpectomy (PRC) were recommended in several studies, but long-term complications of capsular contracture, carpal collapse, and post-traumatic arthritis which lead to poor wrist function were still noted.

We described a 25-year-old male suffering from motor-vehicle accident 3 years ago with neglected chronic lunate dislocation and necrosis, Mayfield classification stage IV. A modified anatomic front and back (ANAFAB) technique was applied for the situation in June, 2020 with a 4-year follow-up. Follow-up was done at postoperative 2 weeks, 6 weeks, 3 months, 6 months, 1 year, 2 years, and 4 years at our outpatient department with radiographic images and functional outcomes recording at the same time. Functional outcomes included visual analog scale (VAS) for pain, The shortened Disabilities of the Arm, Shoulder, and Hand questionnaire and Mayo Wrist Score for functional evaluation.

After surgery, eight weeks of immobilization was adequate and no additional Kirshner wires or other temporary fixation was needed. The modified ANAFAB technique revealed the ability of sustaining significant load on the carpus and radius without pain. The results of Disabilities of the Arm, Shoulder, and Hand questionnaire and Mayo Wrist Score were satisfactory. No significant loss of correction or carpal realignment was detected during the 4-year-follow-up.

Lunate excision following modified ANAFAB reconstruction was applied to achieve carpal stability via the tension of tape and attached FCR tendon to prevent advanced scaphoid flexion and the further rotation of triquestrum. Also, the choice of possible intervention including partial wrist fusion and PRC in the future for the young patient were still preserved. Modified ANAFAB technique might be a resolution in cases of neglected chronic lunate dislocation with necrosis, as it provided carpal stability and soft tissue tension simultaneously and didn’t burn the bridge of possible partial wrist fusion or PRC in the future.

Keywords: Chronic Lunate Dislocation; ANAFAB; Carpal instability