Total Disc Replacement (TDR) or Artificial Disc Replacement (ADR)
The orthopedic procedure where artificial discs replace degenerated discs is called Total Disc Replacement (TDR) or Artificial Disc Replacement (ADR). 1, 2
Procedure Overview
Total disc replacement involves removing the degenerated intervertebral disc and replacing it with an artificial disc prosthesis to preserve spinal motion. 1, 2 The goals are to eliminate the painful disc while maintaining movement at that spinal segment, unlike fusion which eliminates motion. 3
Common Device Types
- The Charité artificial disc is one of the FDA-approved devices for lumbar disc replacement, consisting of a polyethylene core between two metal endplates. 1, 4
- The ProDisc is another artificial disc system used for lumbar degenerative disc disease. 1
- These devices replace the entire disc (nucleus pulposus and annulus fibrosus), though some newer devices focus only on nucleus replacement. 3
Clinical Effectiveness vs. Fusion
Recent evidence from 2021 shows that total disc replacement significantly improved pain, patient satisfaction, reduced reoperation rates, shortened hospital stays, and decreased post-surgical complications compared with lumbar spine fusion in both short-term and long-term follow-up. 5
Key Outcome Comparisons
- Meta-analyses comparing TDR with lumbar fusion found TDR was non-inferior to fusion at 2-year follow-up, with composite "clinical success" rates of 57.1% for Charité vs. 46.5% for fusion, and 53.4% for ProDisc vs. 40.8% for fusion. 1
- Patient satisfaction and physical function scores on SF-36 were significantly better with TDR compared to fusion at 24 months. 2
- Hospital length of stay was significantly shorter with TDR compared to fusion procedures. 2
Important Caveats and Complications
The overall success rates for both TDR and fusion remain modest (40-57%), and complications are substantial with both approaches. 1
Complication Rates
- Major complications with TDR range from 0% to 13% per device implanted in case series, with overall complication rates in trials ranging from 7.3% to 29.1%. 2
- Approach-related complications occur in 2.1% to 18.7% of cases, prosthesis-related complications in 2.0% to 39.3%, and treatment-related complications in 1.9% to 62.0%. 1
- Reoperation at the index level occurs in 1.0% to 28.6% of patients, with trial data showing 3.7% to 11.4% reoperation rates for TDR. 1, 2
Long-Term Issues
- Subsidence (sinking) of the prosthesis into the vertebral body occurred in 16 of 27 patients (59%) in one complication series. 4
- Anterior migration of the device can occur, potentially compressing iliac vessels. 4
- Polyethylene wear becomes evident over time (documented at 12 years post-op). 4
- Adjacent level degeneration occurred in 14 of 27 patients (52%) with persistent complaints. 4
- Facet joint arthrosis at the same or other levels developed in 11 of 27 patients (41%). 4
Approach-Related Complications
- Retrograde ejaculation and sexual dysfunction can occur with anterior lumbar approaches. 4
- Abdominal wall hematomas occurred in 4 of 27 patients (15%). 4
- Early dislocation requiring removal occurred in 2 of 27 patients (7%). 4
Patient Selection Criteria
Only approximately 5% of patients requiring surgery for degenerative disc disease are candidates for artificial disc replacement. 2 The procedure is reserved for patients with:
- Single or two-level lumbar degenerative disc disease unresponsive to at least 6 months of conservative treatment. 2
- Preserved facet joints without significant arthrosis. 4
- No significant spondylolisthesis or spinal instability. 5
- Age typically 30-50 years (younger, more active patients). 4
Clinical Context
When comparing TDR to non-operative management, both surgical fusion and TDR show similar effects to conservative treatment, with low-quality evidence supporting surgical intervention. 5 This underscores the importance of rigorous patient selection and comprehensive conservative management before considering either fusion or disc replacement.