Five-year data suggest limited cervical disc arthroplasty benefits

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Two presentations at the annual conference of the International Society for the Advancement of Spinal Society (6–8 April; Las Vegas, USA) have revealed potential benefits for cervical disc arthroplasty over anterior cervical discectomy and fusion (ACDF). Both using prospective, randomised, five-year clinical trial data based on LDR’s Mobi-C artificial cervical disc, one presentation suggested that arthroplasty could have benefits over ACDF at two levels, whilst the other suggested benefits in favour of arthroplasty in patients younger than 50.

The first study compared results for one- and two-level procedures for both treatment types. Within the one-level cohort, 164 patients were treated by arthroplasty and 81 by ACDF. For the two-level cohort, 225 were treated by arthroplasty, and 105 by ACDF. The researchers assessed outcomes according to visual analogue scale scores for neck and arm pain, Neck Disability Index, range of motion, short form-12 score, patient satisfaction and reoperation rate.

The only significant differences found between one- and two-level procedures were found in those patients treated by ACDF. Both lower success rates and lower improvements were found in the two-level ACDF group—compared with the one- level group—for mean Neck Disability Index. Additionally, lower improvement in short form-12 was observed in the two-level ACDF group compared with the one-level group (8.8 vs. 14, respectively). The rate of reoperations was also higher for the two-level ACDF group (16.1%) than any other group in either cohort (11.1% for one-level ACDF, 4% for two-level arthroplasty and 3% for one-level arthroplasty. The authors suggest that “these results that cervical disc arthroplasty has potential benefits over ACDF, particularly for two-level procedures.”

The second presentation aimed to address the paucity of data analysing the interaction between age and outcomes for ACDF and cervical disc arthroplasty procedures. Participants (n=575) were randomised 2:1, with 389 treated by arthroplasty, and 186 by ACDF. Outcomes data including visual analogue scales, Neck Disability Index and secondary operation rates were collected and subjected to univariate analysis—stratified by age—and multivariate analysis by logistic regression.

No significant difference was found in outcomes results among participants in either treatment group according to age. However, the rate of secondary operation was significantly higher for participants younger than 50 treated by ACDF, when compared with the same age group treated by cervical disc arthroplasty. Within the ACDF group, results showed higher rates of secondary operation within the under-50s group, but these only trended towards significance. The authors concluded that, “a higher rate of subsequent surgery in ACDF patients less than 50 years old suggests that cervical disc arthroplasty may provide a benefit over ACDF for these patients.”

Whilst randomised control trials have suggested benefits of cervical disc arthroplasty over ACDF in the past, clinically-significant results have been sparse (see page 4). The follow-up length of this data may improve its clinical relevance, even if its results only provide limited support to cervical disc arthroplasty.

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