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.

Multiple Hereditary Exostoses is a rare skeletal chondrodysplasia characterized by the presence of a variable number of osteochondromas, usually mostly affecting the long bones but possibly located anywhere. Appearance and growth of exostoses is parallel to the patient’s growth, essentially ending when skeletal maturity is reached.

Its clinical expression is well known and may vary from asymptomatic to severe deformities and is rarely complicated by trasformation to secondary chondrosarcoma (0.5–2%). Research in the field of genetics has lead to identification of 2 responsible genes, EXT1 and EXT2, located respectively on chromosome 8 and 11, both coding for transmembrane glycoproteins involved in the synthesis of heparan-sulfate chains.

A third rare abnormality (EXT3) has been located on chromosome 19 but the responsible gene has not been identified yet.

Seems logical to investigate the genetic basis of the disease and the correlation with clinical aspects, either severity of the deformities and consequent functional impairment and potential for chondrosarcoma.

At the authors’ Institution a total of 550 patients with Multiple Hereditary Exostoses are presently filed. Genetic screening by DHPLC (Denaturing High Performance Liquid Chromatography) and clinicoradiographic orthopedic evaluation has been carried out on 200 patients. So far, 45 mutations have been identified (35 in EXT1 and 10 in EXT2) in 167 patients, 20 of which presented with negative family history and are therefore considered “de-novo” mutations.

Comparison of the clinical data and prospective long term follow-up will possibly clarify different prognosis and risk of secondary chondrosarcoma for different genotypes.

Aims: Purpose of this study was to obtain long term follow-up in patients with Osteofibrous Dysplasia (OFD), in order to investigate natural history of the disease, late results of treatment, and potential risk of Adaman-tinoma development in this setting. Methods: A retrospective study of 48 patients with histologically proven OFD observed at our Institution between 1900 and 1997 was undertaken. Clinico-pathologic features of all cases were reviewed and found consistent with OFD. A clinical status update and current radiographs were obtained in all patients. A subgroup of 21 patients with minimum follow-up of 20 years (21 to 44 years, average 27) was analysed for functional result and adamantinoma development. Functional result according to MTS-ISOLS score correlated with surgical aggressiveness. Results: Best results were observed in patients that received a single biopsy or curettage; worse results were seen after multiple resections or osteotomies and associated with complications as infection or compartment syndrome. No patients had current symptoms or significant symptoms changes nor physical findings, radiographic clues or subsequent radiographic changes suggesting adamantinoma development. Conclusions: OFD is a benign condition; the natural history of the disease has minimal consequences in the adult life. Surgical treatment is usually not necessary and may actually worsen the result because of the potential for severe complications.

The relationship with adamantinoma remains unclear, follow-up is suggested.