Cervical Disk Replacement in Adjacent Segment Disease: Two-Year Follow Up of 51 Cases

Purpose: Prospective consecutive series of 51 prosthetic implantations with over 95 % follow up at two years post-operatively-- Class II Levels of Evidence.

Methods: This is a prospective consecutive study of 51 PCM prostheses inserted in forty-one patients with 60 adjacent segments previously fused or rendered immobile-ten cases were performed as bilevel implantations. The inclusion and exclusion criteria were otherwise identical to the normal FDA prospective IDE criteria with all patients presenting with radiculopathy and a corresponding neurologic deficit confirmed by an MRI compressive lesion.

Results: The mean preoperative cervical lordosis was 2.65 degrees (-32 to 25), mean postoperative lordosis 12.3 degrees (-17 to 30), and the mean improvement was 9.4 degrees of cervical lordosis (range (-15 to 23). EBL = 0 to 100 cc with no patients requiring blood transfusions, Length of surgery = mean 104 minutes (60 to 150) and the length of hospital stay = mean 1.17 days (0 to 3 days). All patients were neurologically intact at follow up with a mean improvement of NDI = 50 % and mean improvement in VAS = 58.3 %. The range of flexion and extension motion at the level of the prosthesis was a mean of 8.9 degrees (range 4 to 20 degrees).

Conclusions: Adjacent levels are a chalenging environment for cervical disk arthroplasty--19 of the 60 previously fused levels had prior cervical instrumentation. 5 patients had previous cervical cages, 2 had cage-plates, 7 patients had previous anterior cervical plates, one had a prior arthroplasty device with HO, and 4 patients had PMMA which required revision. An added potential bonus is the preserved 8.9 degrees of flexion - extension mobility. The PCM appeared to work well in these revision cases. This is the largest study to date investigating prospectively the value of cervical arthroplasty at vertebral levels adjacent to an anterior cervical fusion.