gms | German Medical Science

Objectives/Interrogation: Longstanding un-united scaphoid fractures or scapholunate insufficiency can progress to degenerative wrist osteoarthritis, termed scaphoid non-union advanced collapse (SNAC) or scapholunate advanced collapse (SLAC) respectively. Scaphoid excision and partial wrist fusion is a well-established procedure for the surgical treatment of this condition. In this study we present a novel technique and mid-term results, where fusion is reserved for the lunocapitate and triquetrohamate joints, commonly referred to as bicolumnar fusion. The purpose of this study was to report functional and radiological outcomes in a series of patients who underwent this surgical technique.

Methods: This was a prospective study of 23 consecutive patients (25 wrists) who underwent a bicolumnar carpal fusion from January 2014 to January 2017 due to a stage 2 or 3 SNAC/SLAC wrist, with a minimum follow-up of one year. In all cases two retrograde cannulated headless compression screws were used for inter-carpal fixation. The clinical assessment consisted of range of motion, grip and pinch strength that were compared with the unaffected contralateral side. Patient-reported outcome measures, including the DASH and PRWE scores were analysed. The radiographic assessment parameters consisted of bone fusion and appearance of the radiolunate joint space.

Results and Conclusions: The average follow-up was 2.9 years. The mean wrist extension was 41°, flexion 36° and radial-ulnar deviation arc was 43° (70%, 52% and 63% of contralateral side respectively). Grip strength was 40 kg and pinch 8.9 kg, both 93% of contralateral side. Residual pain for activities of daily living was 1.4 (VAS). The mean DASH and PRWE scores were 19±16 and 29±18 respectively. There were three cases of non-union (fusion incidence 88%). Two wrists were converted to total wrist arthroplasty and one partial fusion was revised and healed successfully. The radio-lunate joint space narrowing had progressed in 2 patients but did not affect their functional outcome.

After bicolumnar carpal fusion using retrograde screws, patients of this series maintained a functional flexion-extension arc of motion, with grip-pinch strength that was close to normal. These functional outcomes and fusion rates were comparable with standard 4-corner fusion technique. This technique has the advantage that compression screws are placed in a retrograde fashion which does not violate the proximal articular surface of the lunate, preserving the residual load-bearing articulation.