Artificial lumbar disc effective at 11-year follow-up

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The Charité III artificial lumbar disc (DePuy Synthes) produces satisfactory clinical and radiological outcomes at 11 years with acceptable complication and reoperation rates, reported Yong Hai, Capital Medical University of China, Beijing, China, at EUROSPINE 2015.

In the short- to mid-term, lumbar total disc replacement has at least equivalent clinical results compared with lumbar fusion. However, as Hai explained to the audience, “questions remain regarding long-term complications and whether total disc replacement can prevent adjacent segment degeneration”.

The 35 patients (15 male and 17 female, average age of 43.4 years) were treated between 1999 and 2002. Of these, 32 patients (with 35 discs) were followed up to 11 years after treatment. Visual analogue scale (VAS) and Oswestry Disability Index (ODI) were used for clinical outcomes.

From baseline to 11-year follow up, patient VAS scores fell from 8.5 to 1.46 (p=0.0015) and ODI scores fell from 41.36 to 13.21 (p=0.0047). Hai said that 28 patients (87.5%) had “a successful clinical outcome”.

Seven patients had a range of motion of less than 2 degrees at 11 years and the mean of the remaining 28 prostheses was 5.4 degrees. Upper adjacent level range of motion decreased from 6.7 degrees to 5.2 degrees (p=0.0143) and lower adjacent level range of motion decreased from 4.5 degrees to 2.4 degrees (p=0.0027). Intervertebral disc height of the index level decreased by 2.1mm compared with preoperative height (p=0.061), and intervertebral disc heights were not significantly affected (p=0.21).

There were no implant failures at final follow-up. Late complications were reported by 15.6% of the patients. These included one case of severe low back and leg pain at seven years diagnosed as adjacent segment degeneration and one pedicle fracture at 20 months. Three patients (9.4%) were found to have prosthesis subsidence, all of which were without symptoms.

Heterotopic ossification was detected in 25 segments (71.4% of segments), none of which were Class IV. Hai reported that no significant difference in segmental range of motion was found in patients with either Class I (20%) or Class II (25.7%) ossification and those with none. Segments with Class III ossification, however, had significantly decreased range of motion compared to those with no ossification (p=0.014). VAS and ODI scores were not significantly different between those with heterotopic ossification and those without.

“For the correct patients, total disc replacement is a safe and effective procedure as an alternative to lumbar fusion,” concluded Hai. “However, whether the procedure can protect the adjacent segment over the long term still requires more evidence.”

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