Short segment coronal plane deformity after two-level lumbar total disc replacement.

STUDY
DESIGN: Case series of 2-level lumbar disc arthroplasties treated by the authors.
OBJECTIVE: Identify a potentially significant failure rate of 2-level disc arthroplasty due to coronal plane instability. SUMMARY OF BACKGROUND DATA: Arthrodesis remains the standard for surgical treatment of degenerative disc disease, despite concerns about adjacent level degeneration and persistent postoperative pain in some patients. Total disc arthroplasty has been proposed as a way to reduce these problems. Intermediate follow-up of 1-level procedures demonstrates promising safety and improved pain scores. Some surgeons are expanding the surgical indications to more challenging settings, including multilevel disease.
METHODS: We report here our experience with 4 cases of failed 2-level disc arthroplasty.
RESULTS: We have seen 4 patients with failed 2-level lumbar arthroplasty, of those 2 performed in Germany and 2 performed in our state by 2 different experienced spine surgeons. The 2 local cases represent 29% (2/7) of all 2-level CHARITE arthroplasties performed within our state. All 4 patients presented within 11 to 13 months of implantation with increased back pain and radicular symptoms. The mechanism of failure was coronal instability due to small deviations of the prostheses from a midline position in all 4 cases.
CONCLUSION: Disc arthroplasty appears to be a safe and effective treatment for 1-level lumbar degenerative disc disease. Although promising biomechanical reports of 2-level models are emerging, we are concerned by the rate of failures of 2-level arthroplasty that we are seeing. It appears that the potential for coronal plane instability increases as the number of levels increases. Given the costs and risks associated with these procedures, we feel that this issue deserves the attention of the spine surgery community despite the limited numbers in this report.