Evaluating osseointegration, bone remodeling and osteolysis after total wrist arthroplasty using photon-counting detector CT.

OBJECTIVE

To evaluate osseointegration, bone quality, and periprosthetic osteolysis following total wrist arthroplasty using photon-counting detector CT (PCD-CT).

MATERIALS AND

METHODS

Nineteen patients with total wrist arthroplasty were examined with PCD-CT the day after surgery, at 6 and 12 months postoperatively. CT images were reviewed and osseointegration and periprosthetic osteolysis were evaluated. Cortical thickness and cortical density were measured. The bones around the implant were divided into zones, and the evaluations were made in each zone.

RESULTS

Osseointegration, visualized as bone ingrowth to the implant, increased in all zones except for the capitate during the 12-month follow-up period. The highest percentage of osseointegration was found in the zones most distant from the joint space, with more than 50% of the circumference of the implant in 84.2% of the patients at the metacarpal screw tip, and in 89.5% of the patients at the radial screw tip at 12 months. Cortical thickness and cortical density decreased in radial distal zones. Osteolytic changes were observed in all but one patient, and increased during the follow-up period, starting near the joint space.

CONCLUSION

Progressive osteolytic changes, and reduction in cortical thickness and density were observed during 12 months after total wrist arthroplasty, especially near the joint space. Concomitantly, continued osseointegration of the implants was observed on PCD-CT images. Osseointegration counteracts the diminished bone contact following osteolysis and may be an important factor to preserved stability.