INTRODUCTION: The first lumbar total disc replacement (TDR) was the Charite. There was much enthusiasm for the potential to restore/maintain motion with these devices. In 2010, the Charite was no longer available on the market with speculation this was due to poor outcomes. This later led to suspicion that TDRs were inherently related to poor safety and/or clinical outcomes. The purpose of this study was to investigate the long-term outcome of patients undergoing TDR using the Charite disc.
METHODS: The study was based on the consecutive series of 556 patients beginning with the first case experience in 2000. Patients were treated for symptomatic disc degeneration after failure of non-operative care. Data were collected from existing records and updated chart review. For patients who were not recently seen in clinic, mailings and/or telephone calls were attempting to collect current outcome data. Outcome measures used were visual analog scales (VAS) separately assessing back and leg pain, Oswestry Disability Index (ODI), and reoperations.
RESULTS: The mean follow-up duration was 108.3 months (median 112.5 months). Current data was collected for 238 patients (mean follow-up 182.2 months), 29 patients were deceased (mean follow-up available from chart review 41.2 months), and 289 were lost to follow-up after multiple attempts to find current contact information and mailings/calls were made for contact or opted not to participate (mean follow-up available from chart review 54.0 months). There was statistically significant improvement from pre-operative to the most recent follow-up in VAS back pain scores (7.1 to 3.8; p<0.001), VAS leg pain scores (4.3 to 2.7; p<0.001), and ODI scores (49.0 to 29.9; p<0.001). Mean improvements in these outcome measures were not significantly different when comparing subgroups based on the patients being in the original FDA trial who received the TDR as an investigational device, those who received it serving as a control patient in subsequent TDR trials, or who received the TDR post-approval at one level, two levels, or as part of a hybrid combined with fusion at an adjacent level. The reoperation rate involving the TDR level was 7.6% (involved 42 patients). The mean duration from TDR implantation to reoperation was 46.6 months, with the longest duration of 165 months. Reoperation procedures included 8 cases of TDR removal with fusion performed (1.4%), 22 patients underwent posterior fusion and/or posterior supplemental fixation (4.0%), 8 cases of decompression at the TDR level (1.4%), 1 case of cyst removal (0.2%), and in the remaining 3 patients (0.5%) not enough detail was available to determine reoperation details. Removals/revisions were accomplished without excessive blood loss or complication.
DISCUSSION: This study found that lumbar TDR with the Charite disc produced good outcomes in the long-term. The reoperation rate at the TDR implanted level was 7.6%. Although there has been comments made about Charite being removed from market for a high failure rate, this has not been supported in the current study or others. The device was no longer marketed after the manufacturer was purchase by a company which already had a TDR on the market.