Abstract
Introduction Adjacent segment disease with radiculopathy and neurologic deficit adjacent to a non-mobile spinal segment is the ideal application for cervical arthroplasty. Not only are the stresses and loads increased but unfortunately the previously fused segment is further compromised by being fixed in a kyphotic position.
Methods This is a prospective study of 40 PCM prostheses inserted in thirty patients with 50 adjacent segments previously fused or rendered immobile—ten cases were performed as bi-level 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). The clinical follow-up was greater than 2 years. 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).
Discussion Naturally, the adjacent segment application of a cervical disc replacement is a challenging clinical environment for cervical arthroplasty – by definition every case had prior surgery. Not only is the cervical spine position often compromised by being in excessive kyphosis, but seventeen of the 50 previously fused levels had prior cervical instrumentation. 5 patients had previous cervical cages, 2 had cage-plates, 5 patients had previous anterior cervical plates, one had a prior arthroplasty device with HO, and 4 patients had PMMA which required revision. Despite the complicated nature of the presenting pathology, the Porous Coated Motion Cervical prosthesis successfully restored some element of cervical lordosis, and restored stability to the cervical segments. An added potential bonus is the preserved 9.4 degrees of flexion – extension mobility. The PCM appeared to work well in these revision cases. This is the world’s largest study to date investigating prospectively the value of cervical arthroplasty in adjacent segment disease.
The abstracts were prepared by Assoc Prof Bruce McPhee. Correspondence should be addressed to him at the Division of Orthopaedics, The University of Queensland, Clinical Sciences Building, Royal Brisbane Hospital, Herston, Brisbane, 4029, Australia.
