Bibliographic record
Abstract
When cervical total disc arthroplasty (cTDR) was introduced, many questioned its efficacy over anterior cervical discectomy and fusion (ACDF). Clinical adjacent segment pathology (CASP) was considered to be part of natural history, and many thought that cTDR would not reduce CASP. Others disagreed based on the evidence available at the time. In vitro studies showed increased stress on the adjacent levels after ACDF in comparison with cTDR. Increased stress was thought to cause accelerated disc degeneration that was seen on imaging studies. CASP does not appear “in a vacuum”; it is preceded by radiographic adjacent segment pathology. Therefore, the logical conclusion was that ACDF increases CASP, and with longer follow-up, adjacent level surgery will be greater with ACDF than with cTDR. Longer-term outcomes from randomized controlled trials show that as a group, cTDR patients do as well or better than ACDF patients, and that CASP is reduced with cTDR. Good outcomes with cTDR have also been confirmed in real-world practice and cost-effectiveness studies.1 One criticism has been that US Investigational Device Exemption studies, although randomized, are not reliable due to the fact that they are industry-sponsored and conflicts of interest may exist. Each study must be scrutinized separately as to its value,2 but longer-term outcomes have shed light on many previously unanswered questions. Before we celebrate, however, there are issues relevant to cTDR that need to be considered. Placing an artificial disc is not the same as placing an implant to achieve fusion. With cTDR, the preparation of host bone endplates and the placement of an artificial disc must be more meticulous and precise. Cervical prostheses can migrate or subside after implantation. Heterotopic ossification may lead to spontaneous fusion, and postoperative kyphosis may develop. Peri-prosthetic osteolysis may occur many years after the surgery, and these patients may need much longer follow-up. Randomized controlled trials have led to better understanding of cervicogenic headaches. Headaches are a very common accompanying symptom for those with cervical degenerative disc disease. Anterior cervical spine surgery, both cTDR and ACDF, led to headache reduction with durable outcomes.3
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.047 | 0.019 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".