PRELIMINARY CLINICAL EXPERIENCE OF THE ISTITUTO RIZZOLI WITH THE GMRS MODULAR RECONSTRUCTIVE PROSTHESIS FOR THE LOWER LIMB.

Abstract

Purpose of this study is to report the preliminary results of the clinical experience of the Rizzoli with a new modular reconstructive tumor prosthesis for the lower limb (GMRS-Stryker).

Material and methods: based on the clinical experience and the review of 842 cases of modular tumor prosthesis for the lower limb, a new prosthetic design was introduced derived from the previous. It is a modular system with a rotating hinge mechanism for the knee and several possible options for the stems, including titanium and chromium-cobalt-molybdenum stems, cemented and uncemented, curved and straight-fluted, with or without hydroxyapatite coating. Moreover adaptors were available to revise older HMRS implants with GMRS components.

Between October 2003 and march 2006 this system was implanted at the Rizzoli in 85 cases. This series included 42 males and 43 females, ranging in age from 8 to 76 years. The sites of prosthetic reconstruction were distal femur in 60 cases, proximal femur in 7, total femur in 1, proximal tibia in 17 cases.

There were 79 oncologic and 6 non oncologic diagnoses. The histological diagnoses of the oncologic cases included 11 giant cell tumors and 68 malignant tumor: 52 osteosarcomas, 7 spindle cells sarcomas, 6 Ewing’s sarcoma, 3 chondrosarcomas. Of the 79 oncologic cases 55 were primary reconstructions with GMRS prosthesis and 24 secondary reconstructions for failure of a previous reconstruction.

In 16 cases HMRS/GMRS hybrid implants were used in reconstruction or revision, using adaptors.

All patients are periodically checked in the outpatient clinic of the Rizzoli.

Complications were reported and analyzed, x-rays were reviewed and pertinent information achieved for each patient. Functional results were assessed according to the MSTS system.

Results: at a short follow up (min 5 months, max 30 months) showed 76 patients NED (11 benign and 65 malignant), 1 NED1 after treatment of local recurrence, 4 NED1 after treatment of metastases.

There was 1 case of infection, treated with removal of the implant and spacer with antibiotics. There were 3 disruptions of the knee extensor apparatus, 1 patellar instability treated by revision of the prosthesis.

Functional result were evaluable in 59 cases and showed a function of 26% to 50% in 14% of pts, of 51% to 75% in 19%, over 76% in 67%. Results were considered good or excellent in 86% of the evaluated patients.

Conclusions: Although the results have been evaluated at a short term follow up, this prosthetic system is promising and it can also be used in some non oncological settings, such as challenging revisions of prosthetic failures with massive bone loss or some post-radiation non unions or allografts failures.