Speaker reports proximal junctional kyphosis can affect postoperative C2-7 SVA

Patients with proximal junctional kyphosis may also present with greater differences in cervical alignment preoperatively and postoperatively.

A retrospective review of a multcenter, prospective database found cervical alignment parameters can affect proximal junctional kyphosis in adults with spinal deformity, according to a presenter at the Cervical Spine Research Society Annual Meeting.

Proximal junctional kyphosis (PJK) is a diagnostic enigma in terms of how it occurs or why, Han Jo Kim, MD, of New York City, said. The retrospective study he and his colleagues conducted determined that patients with adult spine deformity with PJK have a higher C2-7 sagittal vertical axis (SVA).

“The PJK patients in our study had a higher pre- and postoperative difference in the C2-7 SVA, while all other parameters stayed the same,” Kim said.

Using the International Spine Study Group database, Kim and colleagues retrospectively analyzed 190 adults with spinal deformity for whom complete radiographic data were available. In all, 57 patients or about 30% of the patients in the study, had PJK. The remaining 133 patients did not have PJK.

Kim and colleagues divided the patients into two groups; one group with PJK and one group without PJK. There were no differences in the demographics for both groups of patients.

The baseline, 6-weeks and 1-year findings for each group were compared.

PJK incidence

“Patients with a higher postop C2-7 SVA had a higher incidence of PJK and that was also maintained at the 1-year time point. More importantly, the delta parameter of 8 mm vs. 1.2 mm was the difference between those that had PJK and those that did not,” Kim said.

Han Jo Kim

Furthermore, “Patients who have PJK for some reason have a C2-7 SVA that remains to be offset compared to preoperative parameters. All other radiographic parameters were similar to groups included with lumbar lordosis and spinal pelvic parameters and there was no difference in outcomes between the two groups,” he said.

The investigators calculated C2–7 SVA by determining the distance between a plumb line dropped from centroid of C2 and the posterior superior corner of C7.

Kim presented the case of a woman in the study who presented with a 3.5-mm C2-7 SVA. She had posterior spine fusion from T9 to the pelvis; however at 4 days postoperatively she had a 12-mm C2-7 SVA.

Further studies needed

According to Kim, since there was a large preoperative to postoperative C2-7 SVA difference, the patient would be at increased risk of PJK.

“Six weeks later the patient presented with a 32° PJK that had to be followed very closely. Her C2-7 SVA at this point was 16 mm. We saw her again at 6 months, and we saw her PJK had stabilized. The C2-7 SVA also started to decrease a bit, to 5.8 mm. The final, most recent follow-up was a C2-7 SVA of 1.6 [mm], and PJK remained stabilized,” Kim said.

Further studies are needed to determine the factors that lead to higher than usual C2-7 SVA changes postoperatively, he said. – by Robert Linnehan

Reference:
Kim HJ, et al. Paper #5. Presented at: Cervical Spine Research Society Annual Meeting; Dec. 4-6, 2014; Orlando, Fla.

For more information:
Han Jo Kim, MD, can be reached at Hospital for Special Surgery, East River Professional Building, 2nd Floor, 523 East 72nd St., New York, NY 10021; email: hanjokimmd@gmail.com.

Disclosure: Kim reports no relevant financial disclosures.