Abstract
Background: The Wallis Interspinous implant was developed as a minimally invasive and anatomically conserving procedure without recourse to rigid fusion procedures. The initial finite element analysis and cadaver biomechanical studies showed that the Wallis ligament improves stability in the degenerate lumbar motion segment. Unloading the disc and facet joints reduces intradiscal pressures at same and adjacent levels allowing for the potential of the disc to repair itself.
Aims & Methods: The purpose of this prospective study is to demonstrate the survivorship and clinical effectiveness of Wallis implant against low back pain and functional disability in patients with degenerative lumbar spine disease. Patients were assessed pre operatively and post operatively every 6 months by VAS pain score, Oswestry Disability Index, SF-36. All the patients had pre operative radiographs, MRI scans and followed up with interval radiographs. The results were assessed in three sub groups. Group-1 is decompression and stabilisation, group-2 is stabilisation alone, and group- 3 is “Topping off” a fusion.
Results: A total of 211 Wallis Ligaments were inserted in 203 patients between July 2003 and November 2006. In total 179 patients were reviewed with mean age of 54(24–85) were followed for an average 30 months (6–40). The most common level is L4/5 (59%) followed by L3/4. In all the subgroups pain scores and oswestry disability index improved by 50%. And similarly SF-36 scores improved. There is 75–80% good clinical outcome with a survivorship of 98–99%.
Low infection rate of 1.1%. Two cases of prolapsed discs at the same level requiring further discectomy and one case of iatrogenic L4 paraesthesia.
Conclusions: The Wallis ligament represents a successful non fusion alternative in treatment of degenerative lumbar spine disease with least soft tissue damage, quick rehabilitation, less morbidity and associated low complication rate.
The Wallis implant treats pain, preserves mobility, anatomy and stability while being fully reversible, therefore leaving all subsequent options open.
Correspondence should be addressed to: Mr N. J. Henderson, BASS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
