Total disc arthroplasty does not affect incidence of adjacent segment degeneration in the cervical spine

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The results of 93 patients in three prospective randomised clinical trials were presented by Pierce D Nunley, Spine Institute of Louisiana, Shreveport, during the Best Papers session at the North American Spine Society annual meeting in Orlando, USA.

 

“While the clinical outcomes of total disc arthroplasty have proved the procedure to be equally safe and effective to anterior cervical discectomy and fusion in the treatment of cervical degenerative disc disease, no published data thus far provides or assesses the incidence of adjacent segment disease after the procedure,” said Nunley.

 

The investigators examined the incidence of adjacent segment disease at 37-month follow-up in 93 patients with one and two-level cervical degenerative disc disease who received either total disc arthroplasty or anterior cervical discectomy and fusion in three different prospective, randomised clinical trials.

 

Ninety three qualifying patients with documented one and/or two-level symptomatic cervical degenerative disc disease were assigned to receive total disc arthroplasty or anterior cervical discectomy and fusion by an unbiased computer generated randomisation method. The randomisation scheme was 2:1 in favour of the total disc arthroplasty. All three devices had satisfied the US FDA safety criteria for investigational clinical trials.

 

Data at the baseline was collected at the time of enrolment. The patients were followed in the clinic at six weeks; three months; six months; and then annually up to four years after surgery. Success of the index surgery was defined as >30 points reduction in both visual analog score and neck disability index scores from baseline; absence of worsening or new neurological at the index levels.

 

The final scores for visual analog score and neck disability index were similar for both groups with no statistical difference (p=0.693). Both scores showed a significantly better improvement at six weeks, three months and six months post surgery in patients with total disc arthroplasty when compared with scores of those receiving anterior cervical discectomy and fusion (p=0.01).

 

However, the scores tended to juxtapose for the two groups for longer follow-up at one, two, three and four years respectively. These results showed that total disc arthroplasty definitely afforded a quicker recovery and improvement in symptoms when compared to anterior cervical discectomy and fusion in these patients.

 

The presence of documented lumbar disease was statistically significant risk factor for the development of adjacent segment degeneration in both groups (p=0.016). In the presence of concurrent lumbar disease the projected rates for avoidance of adjacent level degeneration dropped significantly to 54.3 ± 1.9% (from 73.5%) for anterior cervical discectomy and fusion and 52.3 ± 1.5% (from 71%) for total disc arthroplasty patients.

 

Total disc arthroplasty demonstrates equivalence of safety and efficacy when compared to anterior cervical fusion in the management of symptomatic degenerative disc disease of the cervical spine.

 

While total disc arthroplasty affords a significantly quicker symptomatic relief, the longer-term outcomes do not prove results superior to those with anterior cervical discectomy and fusion.

 

The clinical evidence at a median follow-up of 38 months failed to corroborate the theory that total disc arthroplasty could potentially reduce the risk of developing adjacent segment disease in patients.

 

The risk of developing symptomatic adjacent segment disease is considerably higher in patients in concurrent lumbar degenerative disease regardless of the surgery performed for cervical degenerative disc disease, Nunley concluded. The paper was selected as the “2010 Outstanding Paper: Surgical Science” by The Spine Journal.

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