The LP-ESP (Spineway, France) is a one-piece lumbar disc prosthesis with a viscoelastic core released on the market mid-2000s. Though it is in use worldwide, its mechanical properties and functional outcomes have sparsely been reported. The objectives of this study were 1) to provide a comprehensive description of postoperative clinical and radiological outcomes and 2) to look for potential prognostic factors that may influence the clinical outcomes.
A consecutive series of 21 monosegmental LP-ESP were analyzed: 16 L5S1 and 5 L4L5 (mean follow-up 2.7 years). The clinical (ODI) and radiological parameters (segmental and lumbar lordosis and ROM) were measured preoperatively and at last follow-up (LFU) in addition to the implant positioning on the lateral radiograph (AP) that was measured as a percentage in reference to the center of the inferior endplate ( <50% meant anterior centering). Analytic statistics were performed with univariate tests.
The mean preoperative ODI was 51 [41;60] and dropped to 30 [19;41] at LFU, p=0.0008. The mean decrease in ODI was 38% [18;59] at the LFU. Half of the patients decreased ODI by 38% and a quarter by 67%. The mean lumbar lordosis went from 53° [49;58] to 56° [52;60], p=0.02. The segmental lordosis increased by 6° [3.5;9], p=0.0001. The mean PI/LL mismatch went from 7° [5;9] to 5° [3;7] at LFU, p=0.05. The mean lumbar ROM went from 30° [30;39] to 33° [25;41], p=0.09. The mean segmental ROM went from 3.4° [2.3;4.4] to 3.8° [2.5;5.1] at LFU, p=0.38. The mean AP was 45% [43;47].
The age, weight, Pfirrmann, and Modic grades were not associated with ODI changes. The following parameters were associated with the ODI decrease: the preoperative PI/LL mismatch (-6% ODI decrease per degree of mismatch [-11; -1.5], p=0.02), the gain of segmental ROM from preoperatively to LFU (-12% ODI decrease per degree of segmental ROM gain [-20;-3.5], p=0.01), and the anterior positioning of the prosthesis (-5% ODI decrease per percent under 50% [1.3;9], p=0.02).
LP-ESP resulted in good functional outcomes with an average decrease in ODI of 38% associated to partial restauration of sagittal balance and mobility. Further investigations appear interesting to improve indications, particularly the degree of preoperative degeneration and disc stiffness.