Effect of intervertebral position on range of motion after artificial lumbar total disc replacement and clinical management

Abstract

To discuss the effect of SB Charité lumbar artificial disc position on intervertebral range of motion (ROM) and clinical management. Between 2004 and 2007, 30 discogenic low back pain patients confirmed by discography underwent 1/2-level total disc replacement (TDR) implantation with 32 prostheses. There were 12 males and 18 females with a mean age of 44 years old (range: 28-55). All indexed levels were inserted between L4-S1 involving L4-5 (n = 9), L5S1 (n = 19) and L4-S1 (n = 2). The clinical outcome was measured by Oswestry disability index (ODI) and visual analogue scale (VAS). Radiographic outcome measures included flexion/extension ROM, restoration of operative level intervertebral disc height, maintenance of disc height at the final follow-up. A technique previously described by McAfee was used to evaluate TDR position in three groups. Paired t test was used to compare the preoperative and postoperative ROM and clinical ODI, VAS scores. Twenty-eight patients were followed-up for 24-60 months with an average of 38 months. All the prostheses were solidly immobilized with the vertebral endplate. No disc prosthesis rupture, dislocation, subsidence or heterotopic ossification was observed. Preoperative ODI, VAS back pain and VAS leg pain scores were 70.34 ± 9.21, 7.46 ± 2.65, 4.81 ± 2.75;and postoperative corresponding scores 7.65 ± 8.61, 0.68 ± 0.69, 0.35 ± 0.32 respectively. The positions of disc prostheses were graded as Group I, excellent, n = 17; Group II, suboptimal, n = 6; Group III, poor, n = 5. Preoperative mean intervertebral flexion/extension ROM (degree) of Group I to Group III were 9.75 ± 2.80, 10.30 ± 1.20 and 10.08 ± 2.43 respectively. The postoperative mean intervertebral flexion/extension ROM (degree): 6.68 ± 3.83, 4.22 ± 3.51 and 3.48 ± 3.56 respectively. Postoperatively all clinical outcome scores were lower than preoperative ones. Disc height was significantly restored. Mean intervertebral ROM decreased versus preoperative. Although there was a tendency of mean intervertebral ROM increasing with a better disc position, no statistical difference was observed. The mid-term clinical outcome of TDR is generally satisfactory. The TDR position influences intervertebral ROM to some extent. Efficient clinical management can reduce prosthetic malposition.