This was a retrospective study of a consecutive series of patients who underwent capitolunate arthrodesis with scaphoidectomy through the lateral approach between 2016 and 2020.
With the same indication as of 4-CA, patients with stage II or III SLAC or SNAC with midcarpal arthrosis, but radiolunate joint preservation, can undergo capitolunate arthrodesis using the lateral approach. Patients with immunological diseases, such as rheumatoid arthritis, are more suitable for total wrist fusion as the generalised carpal joints would be involved. Patients with severe peripheral vascular occlusive problems which compromise the hand circulation should be avoided because the surgical procedure takes place in close approximation to the radial artery and, therefore, could cause stress to the artery during the opening of the wound for surgery.
In our practice, computed tomography is routinely performed before surgery involving bony structures and alignment evaluation. Magnetic resonance imaging is not a routine procedure and is only performed when the cartilage or ligamentous conditions need to be further verified.
Under tourniquet control, a longitudinal or curved incision of approximately 3 to 4 cm was made over the area of the anatomical snuffbox, between the extensor pollicis brevis and extensor pollicis longus. Care should be taken to protect the superficial branch of the radial nerve and the radial artery, which can be found across this operative field. The division of the wrist capsule, which is placed longitudinally underneath, and the scaphoid are then revealed.
After visualisation of the scaphoid, it could be removed, as a whole, with the assistance of a carpal stick or K-wire, or it could be cut into pieces to assist the removal process. Scaphoid excision was followed by radial styloidectomy, which was performed from the scaphoid space under fluoroscopy. If the radial styloid is difficult to remove, the release of part of the corresponding first extensor retinaculum would be helpful.
The arthritic condition of the capitolunate joint could be inspected through the wound. The degenerative articular surface and the subchondral sclerotic bone layer were removed for the preparation of capitolunate arthrodesis. It is important to not remove too much of the subchondral bone because carpal height restoration could then be difficult.
Before fusion of the capitate and lunate, it is important to correct the dorsal intercalated segment instability (DISI). If it is difficult to correct the DISI while simultaneously adjusting the capitate-lunate alignment, the DISI could be corrected first by flexing the patient’s wrist to make the lunate position neutral. Then, the lunate position is maintained by transfixing a 1.0-mm or 1.25-mm K-wire from the dorsal cortex of the distal radius to the lunate, with a small incision for protecting the extensor tendons using mosquito forceps.
After correction of the DISI, the capitate-lunate alignment needs to be corrected by translating the capitate ulnarly to sit completely on top of the lunate. A 1.6-mm K-wire is preferred for pushing the capitate on its side from the lateral wound. The capitate was pushed by the K-wire ulnarly, and the capitate-lunate alignment was checked under fluoroscopy to ensure the capitate sitting completely on top of the lunate. Traction of the fingers distally could help increase carpal height. The K-wire was then aimed at the triquetrum and drilled foreword to transfix the capitate-triquetrum. After capitotriquetrum transfixation (Figs. 1 and 2), the relationship between the proximal and distal carpal row could be maintained.
Following this, the bone graft could be stuffed into the capitoluante junction for arthrodesis. The resected scaphoid can be used as a bone graft. If the scaphoid is not sufficient to afford the bone graft, more cancellous bone grafts can be harvested from the bone window of radial styloidectomy or other bone substitutes can also be an option.
During this procedure involving the lateral approach, we suggest that capitoluanate screw fixation should be performed in a retrograde manner, as the entry points are easier to access as compared to those achieved using antegrade screw fixation.
With a small longitudinal incision of approximately 1 to 1.5 cm over the capitometacarpal joint, the extensor tendons were identified and protected. Under fluoroscopy, two guide pins were inserted from the distal-dorsal corner of the capitate retrogradely to the lunate. Two K-wires of larger diameters (1.25 mm or 1.6 mm) could be used; they would be beneficial for direction control or the handling of the capitate while the K-wire(s) was driven into the capitate before the insertion into the lunate. Then, one of the two K-wires having larger diameters was replaced with the guide pin of a headless screw, and the headless screw was fixed thereafter. The second headless screw was set in the same manner (Figs. 1 and 2).
If there is no good entry point for capitoluante fixation, the guide pin(s) could be set to go through the third metacarpal to have a volar entry point of the distal capitate. The endpoint of the headless screw fixation should be located between the middle and anterior halves of the lunate. It is important to ensure sufficient bone purchase by the screws of both the capitate and lunate (Fig. 3).
After the surgery, the patient was advised a short-arm splint for one month, followed by a removable wrist brace that had to be applied for yet another month. Gentle wrist motion rehabilitation was started after the brace was removed. Strengthening and advanced motion rehabilitation could be started when junctional healing was radiographically confirmed. Weight-bearing work or activities were allowed 3 to 6 months postoperatively depending on the healing condition and functional recovery.
For clinical evaluation of function, wrist range of motion, grip strength, the visual analogue scale (VAS) for pain (where 0 = no pain; 10 = worst pain), the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) questionnaire, and the Mayo wrist score were used as the main evaluations.[6, 7] Radiograph images were taken at every follow-up after postoperative 1 month. The capitolunate angle was measured using the lateral radiographic view, and the carpal height ratio, which was calculated by dividing the carpal height by the length of the third metacarpal, was evaluated using the anteroposterior radiographic view. The radiographic images and functional outcomes were evaluated by two hand surgeons who were not involved in the treatment and follow-up of the patients.