Prosthesis Manufacture and Actual Surgery

A rapid prototype of the medical model used for virtual resection was fabricated using Objet RP system (Objet Geometries Ltd., Israel), and provided to the prosthesis manufacturer (Fig. 10.8(a)). The manufacturer used the physical model to take the dimensional measurements required for accurate manufacture of the saddle component, as well as fit-check the component (Fig. 10.8(b)).

Fig. 10.6 Virtual resection of pelvic bone using a haptic-CAD system

Resection line

Tumour boundary

An additional saddle component with a larger depression was also manufactured to ensure a good fit even in the event of additional resection during actual surgery.

The surgical procedure was carried out as planned. The pelvic bone was resected along the line as indicated earlier, the tumour was removed, and replaced by the pelvic prosthesis. The femoral stem of the prosthesis was inserted into the femur bone, the saddle was placed around the resected portion of the pelvic bone, and the two portions were connected at the ball-and-socket hip joint (Fig. 10.9(a)). The fit between the saddle component and resected pelvic bone was found to be about 1.5 mm, as planned. This was confirmed by post-operative radiographs (Fig. 10.9(b)). The patient was able to walk and navigate stairs aided by a walker within three months of the surgical intervention.

Fig. 10.9 (a) Implantation of prosthesis; (b) post-operative radiograph
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