The effect of single-level, total disc arthroplasty on sagittal balance parameters: a prospective study

Abstract

A prospective radiographic study of the influence of total disc replacement on spinal sagittal balance. The goal of this study was to prospectively determine the effect of a single-level, total disc replacement on the sagittal balance of the spine, especially on sacral tilt (ST), pelvic tilt (PT), and lumbar lordosis. It has been shown that lumbar fusion may deleteriously alter the sagittal balance of the spine, including a decrease in the ST and lumbar lordosis. Clinically, postfusion pain has been shown to be significantly related to a decreased ST, increased PT, and decreased lumbar lordosis, independent of other factors such as pseudoarthrosis. To our knowledge, the influence of total disc replacement on spinal sagittal balance has not yet been reported in the literature. This is a prospective study of 35 patients who received a single level disc replacement using the Maverick Total Disc Arthroplasty system (Medtronic Sofamor Danek, Memphis, Tennessee) by a single surgeon at one institution from March 2002 to September 2003. The preoperative and postoperative radiographic evaluation included standing anteroposterior and lateral full spine films that included the femoral heads. The parameters studied were ST, PT, global and segmental lordosis, and global kyphosis. The average age of the 35 patients studied was 44.3 years (range 35-57). There were 18 females and 17 males. The disc arthroplasty was performed at the L4-L5 level in 19 patients and at the L5-S1 level in 16 patients. The average follow-up was 14 months (range 6-22 months). The preoperative values of global lordosis, ST, and PT were 51.5 degrees , 37.8 degrees , 16.9 degrees and, at last follow-up, they were 51.4 degrees , 37.4 degrees , and 17.5 degrees , respectively. These changes were not significantly different. When the groups were separated according to the level operated, there was still no statistical difference with regard to the overall lordosis, ST, PT or kyphosis from pre- to postoperative period or when the two groups were compared with each other. The level above the prosthesis has always significantly less lordosis. In the present study with use of a motion-preserving Maverick prosthesis, it appears that the patient is able to maintain the preoperative sagittal balance. The prosthesis has enough freedom of motion to allow the patient to maintain the natural sagittal and spinopelvic balance needed to prevent potential undue stress on the muscles and the sacroiliac joint. Although the number of patients is small, this is the first study to our knowledge that evaluates the sagittal balance after motion-preserving total disc arthroplasty.

Sagittal balance parameters influence indications for lumbar disc arthroplasty or ALIF

“…A disc prosthesis in L5-S1 appeared more suitable for backs with a lower sacral slope. Backs with a higher sacral slope produce increased shear constraints and reduce this regulator role due to reduced mobility of the prostheses [10]. It will be possible to vary the different sizes/heights and angles of prostheses in order to optimise their effect on L5-S1, although in practice this effect appeared very limited and random [9].…”

Analysis of post-operative pain patterns following total lumbar disc replacement: results from fluoroscopically guided spine infiltrations

“…One of the primary aims of TDR is to preserve motion and thereby ultimately avoid stress and degeneration of the adjacent segment. Radiographic studies have demonstrated maintained physiological sagittal and spinopelvic alignment following TDR [5,10,33,61]. It has therefore been hypothesized that the above-mentioned fusion-related negative side effects and post-fusion pain patterns could be avoided with TDR.…”

“…In a radiographic study with 35 patients, LeHuec et al [33] concluded that the Maverick prosthesis had enough freedom of motion to maintain the natural sagittal and spinopelvic balance needed to prevent potential undue stress on the muscles and the sacroiliac joints. However, this is the first study to demonstrate that the lumbar facet and sacroiliac joints are a similarly frequent cause of post-operative pain.…”

“…Hypothetically, lumbar disc arthroplasty should serve to avoid stress to the adjacent segments by maintaining motion. Furthermore, it has been shown that physiological sagittal alignment is maintained following TDR [5,6,10,33,61].…”

Total disc replacement compared to lumbar fusion: a randomised controlled trial with 2-year follow-up

“…Total disc replacement (TDR) is one such technique and was developed to avoid the negative effects of arthrodesis by preserving function of the motion segment. The theoretical mechanism of pain relief is based on a combination of complete excision of the painful disc and restoration or improvement of segmental load transfer, sagittal balance and motion [5,14] hoping that this will improve both short-and long-term results. Reduced degeneration of the adjacent spine, as indicated by an in vitro study [6] may be an advantage, but still needs to be proven in prospective studies.…”