RESUMO
BACKGROUND: Degenerative spondylolisthesis is associated with a significant segmental kyphosis at the level of the listhesis. We treated 7 disc spaces with Grade 2 listhesis and/or kyphosis of the slipped disc level with Kineflex disc replacement. METHODS: Out of a single-center prospective registry, involving 310 lumbar disc replacement patients, 7 patients underwent a single-level Kineflex disc replacement at the level of a degenerative spondylolisthesis with either segmental kyphosis or a Grade 2 slip. Preoperative and follow-up radiological parameters studied were: pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis L1-S1, degree of segmental listhesis, segmental lordosis, and range of motion (ROM). Clinical outcome measures were Visual Analog Scale pain score (VAS), Oswestry Disability Index (ODI), and patient satisfaction. RESULTS: Five replacements were performed at the L4-L5 level, and 2 were performed at a L3-4 level, above a pre-existing L4-S1 posterolateral fusion. Mean age was 50 (32-62) years. Average follow-up was 23.8 ± 13.1 months. Six of 7 patients considered their outcome as good or excellent. The mean VAS score decreased from 8.4 ± 1.9 to 2.7 ± 2.2 (P < .01). The ODI decreased from 45.2 ± 9.9 preoperatively to 19.7 ± 12.8 (P < .01). There were increases in lumbar lordosis (from 47.4o ± 10.6 to 61.3o ± 8.0 (P < .03)), in segmental lordosis (from 0.17° ± 7.0° to 16.4° ± 2.0° (P < .03)), and in sacral slope (from 34.5° ± 4.8° to 40.7° ± 4.5° (P < .03)). There were decreases in pelvic tilt (from 22.6° ± 6.3° to 15.5° ± 5.9° (P < .05)), and degree of segmental listhesis (from 24.4% ± 7.7 to 3.7% ± 3.4 (P < .03)). Pelvic incidence and ROM did not change. CONCLUSIONS: Disc replacement resulted in significant improvement in clinical outcome and excellent sagittal balance and slip correction. However, the influence of improved sagittal spinal alignment on clinical outcomes needs to be investigated in larger studies including a control group. CLINICAL RELEVANCE: This study is the first focused on disc replacement in degenerative spondylolisthesis.
RESUMO
BACKGROUND: The Kineflex lumbar disc is a mechanical, unconstrained, re-centering disc prosthesis developed in South Africa. The first implantation took place in October 2002. We present a single-center, prospective, longitudinal study of the first 100 patients treated with the Kineflex lumbar disc. Our objective was to evaluate the insertion technique, clinical outcomes, and patient satisfaction at 2 years postimplantation in 100 consecutive patients with 132 (68 single- and 32 2-level) Kineflex lumbar disc replacements. METHODS: We determined the exact central placement of all disc implants in the coronal and midsagittal planes. We measured clinical outcome with the Oswestry disability index (ODI), our own questionnaire, and the time needed to return to work. All patients received radiological and clinical follow-up assessments for 2 years after the index procedure. RESULTS: Forty-three patients were female. The mean age of the patients at operation was 44.9 years (range, 23-63 years). Postoperative hospitalization averaged 2.8 days (range, 2 to 8 days). All patients who were employed before surgery returned to work 31 ± 16.8 days after the operation. Fifty-six percent of operated disc levels had intervertebral disc heights of less than 5 mm. A 2-year clinical outcome was available for 98 of the 100 patients (58 excellent, 30 good, 7 fair, 3 poor). The ODI score improved from 47.8 ± 16.0 preoperatively to 14.2 ± 14.0 (P < .01) at 2 years. At 2 years, 95% of disc implants were radiologically in the ideal position. The insertion technique, with a released prosthetic mechanism for final placement, allowed ideal placement in the sagittal plane in 98% of discs. The radiographic placement accuracy achieved was equal in patients with preoperative intervertebral disc height below and above 5 mm. CONCLUSIONS: Good short-term clinical results were achieved with the Kineflex disc in a heterogeneous patient group with a high number of patients with advanced disc degeneration, severe disc space narrowing, and lumbar flat-back deformity. In this cohort, accurate implant placement could be achieved in our first 100 patients. CLINICAL RELEVENCE: This is the first report on the Kineflex mechanical lumbar disc prosthesis.
RESUMO
BACKGROUND: Failed fusion surgery remains difficult to treat. Few published data on disc replacement surgery after failed fusion procedures exist. Our objective was to evaluate outcomes of junctional lumbar disc replacement after previous fusion surgery and to correlate outcome with radiological changes to parameters of sagittal balance. METHODS: Out of a single-center prospective registry of 290 patients with 404 lumbar disc replacements, 27 patients had had a previous lumbar fusion operation on 1 to 4 lumbar segments and had completed a mean follow- up of 33 months (range: 18-56). We correlated the clinical outcome measures (patient satisfaction, 10-point pain score, and Oswestry Disability Index [ODI] score) to parameters of spinal sagittal alignment (sacral tilt, pelvic tilt, pelvic incidence, and lumbar lordosis). RESULTS: Postoperative hospital stay averaged 3.3 days (range: 2-8). Previously-employed patients went back to their jobs with a mean of 32 days (range: 21-42) after the procedure. At the latest follow-up, 1 of the patients considered the outcome to be poor, 3 fair, 8 good, and 15 excellent. Twenty-four patients "would undergo the operation again." Average pain score decreased from 9.1 ± 1.0 (SD) to 3.2 ± 2.1 (P < .01). Average ODI decreased from 50.2 ± 9.9 preoperatively to 21.7 ± 14.2 (P ≤ .01). We found the change in pelvic tilt to be an independent predictor of better clinical outcome by multivariate analysis (P < .05). CONCLUSIONS: In patients with junctional failure adjacent to a previous posterolateral fusion, disc replacement at the junctional level(s), compared with osteotomy and fusion surgery, offers the advantage of maintaining segmental mobility and correcting the flat-back deformity through a single approach with less operative time and blood loss. Early- to intermediate-term results are promising. The influence of changes in spinal sagittal alignment on clinical outcome needs to be addressed in future research. CLINICAL RELEVANCE: This is the first study on "junctional disc replacement patients" correlating clinical outcome to changes in spinal/pelvic alignment.
