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Background: Midcarpal arthrodesis is a treatment of choice in patients with midcarpal arthritis. Traditionally a four corner fusion has been favoured, however recent research has shown improved results when the triquetrum and scaphoid are excised. There is no clear evidence as to which remaining bones should be fused or which implants should be used. The purpose of this study is to compare the biomechanics of midcarpal arthrodesis after scaphoid and triquetrum excision, using memory staples or cannulated screws, in recognised construct patterns., Methods: 36 identical sets of carpal bones were 3D printed from acetyl butyl styrene. Midcarpal arthrodeses were performed in three configurations with shape memory alloy staples or headless compression screws. This gave 6 treatment groups; lunocapitate single staple or screw, lunocapitate with 2 staples or screws, three corner fusion with 2 staples or screws. Peak torque to distraction was measured and analysed., Results: The peak torque to distraction was significantly greater in almost all constructs utilizing screws compared to staples, with two lunocapitate screws having the highest peak torque at both 1 and 3 mm distraction with 244 Nmm and 749 Nmm respectively (p < 0.05)., Conclusions: Constructs utilizing screws have a peak torque to distraction significantly higher when compared to staples. Our recommendation when performing a midcarpal arthrodesis after scaphoid and trapezium excision is to fuse the midcarpal joint with 2 headless compression screws.

Purpose: To review the results and indications of simultaneous four finger metacarpophalangeal joint fusions., Methods: The clinical records and X-rays of nine patients undergoing the above procedure were reviewed. The indication for surgery was to reverse severe metacarpophalangeal joint flexion deformities in eight patients, and following a traumatic four finger amputation in one. Seven patients returned for follow-up assessment. The fusions were performed with a tension band wire technique, aiming for 20 degrees of flexion for index and middle fingers and 40 degrees in the ring and little fingers. Time to radiological fusion and position of fusion, and improvement in function and appearance were assessed., Results: All joints were radiologically fused between six and 12 weeks. The average position of fusion of index and middle fingers was 20 degrees (range: 15-30) and ring and little fingers was 40 degrees (range: 35-50). Appearance was improved in all patients. Improved function was reported by four patients, and improved ease of hygiene and general care in four patients with non-functioning or poorly functioning hands., Discussion: Simultaneous fusion of all four finger metacarpophalangeal joints may be considered as a primary procedure to reconstruct destroyed metacarpophalangeal joints due to inflammatory arthropathy or trauma, and for inability to correct deformity or maintain the correction with soft tissue procedures for patients with cerebral palsy, adult brain injury and arthrogryposis.