Is anterior decompression and fusion more beneficial than laminoplasty for K-line (+) cervical ossification of the posterior longitudinal ligament? An analysis using propensity score matching
Authors: Inoue Takaki , Maki Satoshi , Yoshii Toshitaka , Furuya Takeo , Egawa Satoru , Sakai Kenichiro , Kusano Kazuo , Nakagawa Yukihiro , Hirai Takashi , Wada Kanichiro , Katsumi Keiichi , Fujii Kengo , Kimura Atsushi , Nagoshi Narihito , Kanchiku Tsukasa , Nagamoto Yukitaka , Oshima Yasushi , Ando Kei , Takahata Masahiko , Mori Kanji , Nakajima Hideaki , Murata Kazuma , Matsunaga Shunji , Kaito Takashi , Yamada Kei , Kobayashi Sho , Kato Satoshi , Ohba Tetsuro , Inami Satoshi , Fujibayashi Shunsuke , Katoh Hiroyuki , Kanno Haruo , Imagama Shiro , Koda Masao , Kawaguchi Yoshiharu , Takeshita Katsushi , Matsumoto Morio , Ohtori Seiji , Yamazaki Masashi , Okawa Atsushi , _ _ 
Published: February 2022

OBJECTIVE
It is unclear whether anterior cervical decompression and fusion (ADF) or laminoplasty (LMP) results in better outcomes for patients with K-line–positive (+) cervical ossification of the posterior longitudinal ligament (OPLL). The purpose of the study is to compare surgical outcomes and complications of ADF versus LMP in patients with K-line (+) OPLL.

METHODS
The study included 478 patients enrolled in the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament and who underwent surgical treatment for cervical OPLL. The patients who underwent anterior-posterior combined surgery or posterior decompression with instrumented fusion were excluded. The patients with a follow-up period of fewer than 2 years were also excluded, leaving 198 patients with K-line (+) OPLL. Propensity score matching was performed on 198 patients with K-line (+) OPLL who underwent ADF (44 patients) or LMP (154 patients), resulting in 39 pairs of patients based on the following predictors for surgical outcomes: age, preoperative Japanese Orthopaedic Association (JOA) score, C2–7 angle, and the occupying ratio of OPLL. Clinical outcomes were assessed 1 and 2 years after surgery using the recovery rate of the JOA score. Complications and reoperation rates were also investigated.

RESULTS
The mean recovery rate of the JOA score 1 year after surgery was 55.3% for patients who underwent ADF and 42.3% (p = 0.06) for patients who underwent LMP. Two years after surgery, the recovery rate was 53.4% for those who underwent ADF and 38.7% for LMP (p = 0.07). Although both surgical procedures yielded good results, the mean recovery rate of JOA scores tended to be higher in the ADF group. The incidence of surgical complications, however, was higher following ADF (33%) than LMP (15%; p = 0.06). The reoperation rate was also higher in the ADF group (15%) than in the LMP group (0%; p = 0.01).

CONCLUSIONS
Clinical outcomes were good for both ADF and LMP, indicating that ADF and LMP are appropriate procedures for patients with K-line (+) OPLL. Clinical outcomes of ADF 1 and 2 years after surgery tended to be better than LMP, but the analysis did not detect any significant difference in clinical outcomes between the groups. Conversely, patients who underwent ADF had a higher incidence of surgery-related complications. When considering indications for ADF or LMP, benefits and risks of the surgical procedures should be carefully weighed.