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Motor and sensory function improved 6 weeks after cervical disc arthroplasty, ACDF
Post-hoc analysis finds that most improvements occurred within the first 6 postoperative weeks.
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Most neurologic deficits associated with cervical pathology improved by 6 weeks after arthroplasty or fusion surgery, and the improvements were maintained 2 years later, according to data presented at the North American Spine Society 24th Annual Meeting.
“In the majority of cases, sensory and motor improvement occurred within the first 6 weeks following surgery,” said Jacob Buchowski, MD, assistant professor of orthopedic surgery and neurological surgery and director of the Center for Spinal Tumors at Washington University in St. Louis, Mo. “Compared with motor function improvement, fewer sensory deficits improved following surgery in both arthroplasty and fusion patients, and more worsened by 2 years. There were no differences between the arthroplasty and fusion groups for either motor or sensory deficit improvement.”
Prospective review
Buchowski and his colleagues performed a post-hoc analysis of prospectively collected data from an arthroplasty FDA investigational device exemption (IDE) study to determine neurologic outcome in patients who had single-level cervical degenerative process that led to radiculopathy and/or myelopathy.
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Two hundred forty-two of the patients underwent a single-level cervical disc arthroplasty, using the Bryan Total Disc Replacement (Medtronic), and 221 had anterior cervical discectomy and fusion (ACDF). Two hundred twenty-nine of the arthroplasty patients and 194 ACDF patients had a minimum 2-year follow-up, according to Buchowski. Motor scores were determined using manual muscle testing of five muscle groups on each side in the arms and legs. Sensory function was measured for each dermatome, and the researchers were provided with a sum of the measurements.
Most improved
Buchowski and his colleagues found that 74.7% of the arthroplasty patients and 76.3% of the ACDF patients had preoperative motor deficits. At 2 years, improvement was seen in 96.5% of the arthroplasty patients with preoperative deficits and 95.3% of the fusion patients with preoperative deficits; 2.9% in the arthroplasty group and 4.7% in the ACDF group worsened at 2 years.
Preoperatively, sensory deficits were present in 69.4% of arthroplasty patients and 68.6% of ACDF patients. At 2 years, 89.3% of the arthroplasty patients with preoperative deficits and 85.3% of the ACDF patients with preoperative deficits improved. Sensory function worsened in 6.9% of arthroplasty and 13.5% of ACDF patients.
Buchowski noted that a major limitation of the study was the researchers’ inability to determine at which level the motor or sensory deterioration was occurring.
“Because the scores were summed, it’s impossible to tell whether the deterioration in the sensory function occurred at the operative level or if it occurred at the adjacent level,” Buchowski said. – by Tina Dimarcantonio
Reference:
- Buchowski J, Anderson PA, Riew KD. Improvement of neurologic deficits following anterior cervical spine surgery. Presented at the North American Spine Society 24th Annual Meeting. Nov. 10-14, 2009. San Francisco.
- Jacob Buchowski, MD, assistant professor of orthopedic surgery and neurological surgery and director of the Center for Spinal Tumors at Washington University in St. Louis, St. Louis, Mo., can be reached at buchowskij@wustl.edu.
This study confirms what we have always understood in the past — that if you have a neurologic deficit from anterior cord compression, taking that pressure off anteriorly can predictably result in improvement in arm pain and neurologic deficit. This confirms what we have always thought to be the case, but never before have we had such consistent level 1 data. Now, with a series of IDE studies looking at arthroplasty and fusion, we have objective data for both the fusion group and the arthroplasty group that anterior surgery is effective in improving neurologic symptoms. This in general will not have any impact on clinical practice, because this is something we have always known to be the case, and it’s just supported now by better evidence.
– Alex Vaccaro, MD, FACS
Professor of
Orthopedic Surgery and Neurosurgery, Thomas Jefferson University Hospital
Philadelphia, Pa.