Abstract
Background
Wallis implant was developed in 1986 to stiffen unstable operated degenerate lumbar segments while preserving some intervertebral mobility. The long-term results of first-generation Wallis implant from developers were promising. However, documentation pertaining to safety and efficacy of second generation Wallis implant is sparse in literature.
Purpose
The objective of this study was to assess the clinical outcome of the second generation Wallis interspinous device for degenerative lumbar disc disease.
Study design
Prospective consecutive single surgeon series.
Methods
Patients were selected according to recommendations by developers of Wallis implant. Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) were used to assess patient outcomes. Implant failure was determined by disc recurrence, implant removal and revision.
Results
25 patients (13 male, 12 female) with mean age of 51 years (range 47-76) had Wallis implantation (22 one level and 3 two level). Clinical outcome data at average of 60 months (47-76) available for 24 patients (96% FU)
Mean ODI scores decreased from 59.1% pre-operatively to 24.7 and 40.5% at 2 years and 5 years follow up, respectively. 34.4 points change from baseline at 2 years and 18.6 points at final follow-up.
Mean VAS scores decreased from 7.2 to 3.0 and 4.8 cm for back pain at 2 and 5 years; from 6.8 to 3.8 and 4.2 cm for leg pain at 2 and 5 years follow-up, respectively.
Taking a 24 point change in ODI as representing good outcome 96 % (24 patients) of study subjects achieved this at 2 years.
Taking a 16 point change in ODI as representing minimum change needed for clinical success 40% (10 patients) failed to achieve this at 5 years.
2 revisions have occurred so far (8% failure rate)
Conclusion
The results of our series indicate that the study device is safe and efficacious in the treatment of symptomatic lumbar degenerative discs. However, good clinical outcome obtained at early years is not maintained in medium-term.
Interest Statement
There was no commercial support or funding of any sort.
