gms | German Medical Science

Objectives/Interrogation: Arthroscopic cancellous bone grafting of the scaphoid is a technique with many potential advantages - high union rates, minimally invasive and less deep scarring. The associated fixation is generally buried Kirschner wire fixation, as described by PC Ho. The fixation must remain in situ until union is confirmed, and generally mobilisation must be minimal while the wires remain, due to the risk of migration and soft tissue irritation.

Since cancellous bone grafting is performed, which will not resist compression, headless compression screws are not preferred, since they may lead to deformity, in the presence of a defect. We have designed a non-compressive neutralisation screw, which will hold the scaphoid in its corrected position before the cancellous graft is inserted.

Study Material: The rationale for the implant design is discussed, and the surgical considerations which have been considered in fine tuning the technique.

Finite element analysis of the implant versus 3 K-wires is presented.

The surgical technique and some cases are presented.

Operative Method: Dry arthroscopy is the presenter's preferred option. My preference is for 3 midcarpal ports, the most ulna is the radial midcarpal. The non-union is debrided to cancellous bone.

The wrist is then removed from traction. If there is deformity, a temporary Linscheid wire may be used to stabilise the lunate to the radius. The wrist is then extended over a bump and a retrograde K-wire inserted with image intensification. The correction and wire position are assessed with fluoroscopy. The wire is over-drilled, then the screw inserted. Traction is re-applied and the joint and fixation assessed arthroscopically. Cancellous bone graft is then inserted and sealed with fibrin glue.

Results: The interference screw fixation is markedly more stable than 3 K-wire fixation, as assessed by finite element analysis. Some cases where passive motion has begun prior to bony union are presented.

Discussion: This screw design has the potential advantages of increased stability, which may allow the surgeon to hold correction of deformity without the use of a post-operative Linscheid type wire. It also allows earlier motion, which in conjunction with arthroscopic surgery, may lead to improved range of motion. It also avoids associated K-wire complications and the need for K-wire removal.

Conclusion: The role of intereference, non-compressive screw fixation with arthroscopic scaphoid bone grafting is presented.