VISCOELASTIC LUMBAR DISC REPLACEMENT WITH A TITANIUM-POLYOLEFIN-TITANIUM PROSTHESIS – 5 YEAR OUTCOMES OF THE INITIAL SERIES

Abstract

This prospective study was carried out to document the efficacy of lumbar disc replacement using a viscoelastic prosthesis in the medium term.

Eleven patients were included in the pilot study of this prosthesis, with an average age at surgery of 41, and these have now reached 5 years follow-up. They have been followed up prospectively with clinical and radiological evaluation, and outcome assessment using the Oswestry Disability Index (ODI), Visual Analogue pain scales (VAS), and the Low Back Outcome Score (LBOS).

There have been 3 revision operations in patients who failed to get lasting symptomatic relief. Two patients have had their prosthesis removed with revision to an inter-body fusion supplemented with pedicle screw fixation, and one has been revised to a posterolateral fusion while retaining an apparently well functioning prosthesis.

In the 8 ‘survivors’ the improvement in the ODI, VAS and LBOS seen at the 2 year follow-up has been maintained in the longer term. Fine cut helical CT scan has shown that the prosthesis has undergone mechanical failure in 3 patients, without significant clinical problems. One patient (with a virtually perfect ODI and LBOS) appears to have undergone ‘autofusion’ with significant heterotopic ossification anterior to the disc prosthesis.

In conclusion, despite some successes, the rate of early failure of this prosthesis, both radiologically and clinically, is unacceptable, and its use has therefore been abandoned.