Where should a laminoplasty start? The effect of the proximal level on post-laminoplasty loss of lordosis

Abstract Background Context Open-door laminoplasty is a useful operation in the surgical management of cervical myelopathy with favorable outcomes and relatively low complications. One potential undesirable outcome is a decrease in cervical lordosis postoperatively. It is unknown whether the most proximal level undergoing laminoplasty affects the magnitude of loss of lordosis. Purpose To compare the loss of cervical lordosis postoperatively in patients for whom the most proximal level undergoing laminoplasty is C3 versus C4. Study Design/Setting Retrospective radiographic review at an academic center. Patient Sample 65 patients at a single institution who underwent plated open door laminoplasty for cervical myelopathy by multiple surgeons over a five-year period were included. Outcome Measures The primary outcome was change in cervical lordosis, which was the difference in C2-T1 Cobb Angle between the postoperative and preoperative films. Methods Patients were divided into two groups based on the most proximal vertebral level undergoing laminoplasty. Forty-nine patients underwent laminoplasty beginning at C3, while sixteen patients underwent laminoplasty beginning at C4. The C2-T1 Cobb angle was measured on the preoperative film and on the final postoperative follow-up film. The difference between these values was calculated for each patient, and the mean of the differences for the C3 group was compared to that of the C4 group. Results When C3 was the proximal plated laminoplasty level, loss of lordosis averaged 9°. In contrast, when C4 was the proximal plated level, loss of lordosis was significantly less and averaged only 3° (p=0.047). In the group as a whole, mean preoperative lordosis was 18° compared with 11° postoperatively, for an overall 7° loss of lordosis. Conclusions Starting the laminoplasty at C4 led to significantly less loss of lordosis than starting at C3. When the pattern of spinal cord compression does not require laminoplasty at C3, consideration should be given to making C4 the most cephalad laminoplasty level rather than C3 in order to better preserve lordosis.