[Incorporation of bone allografts with the use of Octopus revision system in total hip arthroplasty].

PURPOSE OF THE STUDY

The study describes the revision arthroplasty of hip joints with grade III acetabular defects, as rated according to Paprosky, employing morsellized bone allografts and the Octopus revision acetabular system.

MATERIAL

In the period from 1998 to 2002, a total of 8297 operations were performed in our Department; of these 1527 (18.4%) were total hip replacements. In this group, 267 (15.5%) revision arthroplasties were carried out, with the the Octopus revision system being used in 32 patients (age range, 30 to 79 years; average age, 60.3 years). The average period between the initial surgery and reimplantation was 6.5 (range, 2-14) years.

METHODS

Acetabular defects were filled with morsellized cancellous bone allografts (one to three femoral heads per patient) obtained from the tissue bank. In nine patients, allografts were combined with hydroxypatite (Biovan). Osteointegration of the bone allografts and, if it occurred, loosening of the implant were checked by X-ray examination.

RESULTS

The patients were examined at intervals of two months. The average Harris hip score was 76 points at 1 to 3 years. None of the patients had deep post-operative wound infection; in one patient, the distal hook of the Octopus system broke off. The complete incorporation of allografts was seen on X-ray images in 28 patients; at follow-up, a radiolucent zone between the acetabular bed and the allograft was still visible in four patients. No implant loosening was recorded.

DISCUSSION

The Octopus system has an advantage of using morsellized allografts instead of solid ones that are associated with poorer incorporation and a higher risk of loosening. The remodeling of an allograft below the ring leads to the production of bone tissue, which is useful if revision arthroplasty were to be performed.

CONCLUSION

Based on their experience, the authors regard the Octopus revision system with the use of morsellized bone allografts from the tissue bank as an effective surgical procedure for the treatment of Paprosky grade III acetabular defects. The allografts below the ring are fully incorporated and remodeled; as a result the initial defect is gradual filling with the patient's own tissue, which has very good clinical outcomes.