TANTALUM HIP SCREW FOR FEMORAL HEAD OSTEONECROSIS

Abstract

Femoral head osteonecrosis is a progressive disease that affects patients in the third to the fifth decades. It is probably a multifactorial disease since many patients that have the known risk factors never develop it and others develop the disease without any risk factors.

There isn’t any totally effective treatment that can stop the disease and prevents bone collapse, but it is known that operative treatment gives better results than conservative treatment in Ficat stages I and II.

The authors began in October of 2003 the surgical treatment of pre-collapse patients (Ficat stage I and II) with the tantalum hip screw hopping that it could prevent progression to collapse.

The tantalum is an innovating new metal with an excellent bio-integration and with mechanic properties very close to normal bone. The tantalum hip screw gives structural support to the necrotic bone segment, permits immediate charging of the affected hip and pretends to be a substitute to peroneal graft.

There isn’t any published clinical result of the use of the tantalum hip screw in the literature to date.

Between the October of 2003 and November of 2004 we made 10 such procedures in 8 patients with mean age of 44 years. The patients were Ficat grade I and II and we could identify that most of the patients had been taking corticosteroid medication. There was one hip with less than 15% of extension and 9 with a severe extension (more than 30% of the femoral head from the University of Pennsylvania system of classification and staging).

There was rapid radiographic progression of the disease in all patients but one with bilateral involvement. There was progression for femoral head collapse in 70% of the patients despite the femoral hip screw. In 3 patients the collapse led to screw protrusion on the acetabulum and needed hip arthroplasty, on average, 12 months after screw implantation.

The harris hip score of the 5 patients (7 hips) than weren’t submitted to hip arthroplasty gave a good result in 1 patient and a fair result in 3 patients (4 hips). There was a poor result in the other patient.

The tantalum hip screw made it more difficult to do a hip arthroplasty but it didn’t make it impossible.

This study shows that the tantalum hip screw didn’t prevent the progression of the femoral neck osteonecrosis in all but one patient with an initial Ficat grade IIa.

The fact that 9 in 10 patients had a severe extension of the disease (> 30% of the femoral head diameter) could have prevented the success of the tantalum hip screw because the area of sustention of the screw was limited and the disease continued to progress around the screw.