K-line (-) in the Neck-Flexed Position in Patients With Ossification of the Posterior Longitudinal Ligament Is a Risk Factor for Poor Clinical Outcome After Cervical Laminoplasty.
METHODS
Retrospective study comparing postoperative clinical outcomes after cervical laminoplasty between K-line (-) ossification of the posterior longitudinal ligament (OPLL) and K-line (+) OPLL in the neck-flexed position.


OBJECTIVE
To investigate postoperative outcomes using Japanese Orthopedic Association (JOA) scores, and grip-and-release (GR) and foot-tap (FT) test scores after laminoplasty in patients with K-line (-) OPLL in the neck-flexed position.


BACKGROUND
Cervical laminoplasty has been reported to lead to poor outcomes in K-line (-) OPLL and good outcomes in K-line (+) OPLL. The cervical spine, however, continues moving in the extension and flexion direction after laminoplasty.


METHODS
Patients with cervical myelopathy were divided into K-line (+) and (-) in the neck-flexed position. We compared postoperative outcomes after cervical laminoplasty using recovery rate, as assessed by the JOA score and degree of improvement in the six JOA score items, and performance, as assessed by GR and (FT) tests, between patients with K-line (+) OPLL (n = 18) and K-line (-) OPLL (n = 23) in the neck-flexed position.


RESULTS
Recovery rate of JOA score (23.8%) of patients in the K-line (-) group was significantly lower (P = 0.028) than that (46.3%) of K-line (+) group in the neck-flexed position. In the K-line (+) group, significant improvements were seen in all JOA-score items except bladder function; however, in the K-line (-) group, improvements were seen only in upper- and the lower-extremity sensory functions. In the K-line (+) group, mean GR and FT tests significantly improved, but in the K-line (-) group, only mean FT test significantly improved.


CONCLUSIONS
The K-line (-) OPLL in the neck-flexed position is a risk factor for poor clinical outcome after cervical laminoplasty.


METHODS
4.
Department of Orthopedic Surgery, Odate Municipal General Hospital, Odate, Japan.
Kazunari
K
Takeuchi
Department of Orthopedic Surgery, Odate Municipal General Hospital, Odate, Japan.
Toru
T
Yokoyama
Department of Orthopedic Surgery, Towada City Hospital, Towada, Japan.
Takuya
T
Numasawa
Department of Orthopedic Surgery, Japan Community Health Care Organization, Akita Hospital, Akita, Japan.
Yoshihito
Y
Yamasaki
Department of Orthopedic Surgery, Towada City Hospital, Towada, Japan.
Hitoshi
H
Kudo
Department of Orthopedic Surgery, Kuroishi General Hospital, Kuroishi, Japan.
Taito
T
Itabashi
Department of Orthopedic Surgery, Kuroishi General Hospital, Kuroishi, Japan.
Shunfu
S
Chin
Department of Orthopaedic Surgery, Hirosaki University School of Medicine, Hirosaki, Japan.
Kan-Ichiro
KI
Wada
D000328:Adult; D000368:Aged; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D006801:Humans; D065406:Laminoplasty / Q000379:methods; D017846:Longitudinal Ligaments / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017887:Ossification of Posterior Longitudinal Ligament / Q000601:surgery*; D010012:Osteogenesis / Q000502:physiology*; D011184:Postoperative Period; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome