136 - Influence of Preoperative Sagittal Balance and Roussouly’s Back Type o...

General Session: Lumbar

Presented by: A. Faure - View Audio/Video Presentation (Members Only)


A. Faure(1), C-H. Flouzat Lachaniette(1), M. Khalife(1), A. Poignard(1), J. Allain(1)

(1) CHU Henri Mondor, Créteil, France


Background Data: Excellent clinical two-year outcome after lumbar total disc replacement (TDR) is well established. However, whereas sagittal balance parameters are reported to influence the outcome of any spinal fusion, to our knowledge, no studies evaluated the influence of these parameters in TDR surgeries.

Purpose of the Study: To assess the influence of preoperative sagittal balance parameters, including Roussouly's classification defining 4 shapes of spine and C7/Sacro-Femoral Distance (SFD) ratio, on postoperative clinical and radiological outcomes following single-level TDR.

Methods: This is a prospective study in a continuous series of 78 patients presenting with low back pain due to degenerative disc disease (DDD) at one level and operated on with Mobidisc® TDR (LDR Medical) at L4-L5 or L5-S1. Prospective data were collected before surgery and at 24 months. Pelvic parameters, C7/ SFD ratio, lumbar lordosis (LL), and the four back types in the Roussouly classification were studied in standardized radiographs of the whole spine. Disability and pain were assessed using the Oswestry Disability Index (ODI), and the Lumbar and radicular Visual Analog Scale (L- and R-VAS), respectively.

Results: Before TDR, most patients were either Roussouly type 2 or 3 back (40% and 45%), few were type 4 (13%) or type 1 (2%). Preoperatively, based on C7/ SFD ratio, 17% of patients had sagittal imbalance and 23% had compensated sagittal balance, whereas they were only 8% to be imbalanced postoperatively. The overall gain of LL is significantly correlated with the importance of the initial sagittal imbalance (R = 0,27 and P = 0,005). 25% of patients went from a preoperative type 2 to a postoperative type 3 back. The overall results revealed a significant improvement of VAS and ODI scores (P < 0.05), regardless of their initial back type or state of sagittal imbalance (Figure 1 and 2) (P< 0.05). The most pronounced changes occurred in patients with Roussouly type 4 operated at L5-S1 level: lumbar and radicular VAS were respectively divided by 5 and 4.8, and ODI decreased by 34 points.

Conclusions: This study confirms the excellent results obtained at two-year follow-up after TDR. 40% of patients had type 2 backs, confirming the correlation between flat backs and DDD. Restoring lordosis, TDR enabled patients to change the shape of their spine, confirming its regulatory role, which allows patients to position themselves appropriately. According to our data and contrary to previously published reports, excellent results were obtained in Roussouly type 4 at L5-S1 level, which is not a contraindication for TDR.

Figures:R1 to R4: Roussouly 1 to 4. *=significant result

Figure 1

Figure 2