Minimum 2-year outcome of cervical laminoplasty with deep extensor muscle-preserving approach: impact on cervical spine function and quality of life

Abstract

In this retrospective cohort study, two surgical methods of conventional open-door laminoplasty and deep extensor muscle-preserving laminoplasty were allocated for the treatment of cervical myelopathy, and were specifically compared in terms of axial pain, cervical spine function, and quality of life (QOL) with a minimum follow-up period of 2 years. Eighty-four patients were divided into two groups and received either a conventional open-door laminoplasty (CL group) or laminoplasty using a deep extensor muscle-preserving approach (MP group). The latter approach was performed by preserving multifidus and semispinalis cervicis attachments followed by open-door laminoplasty and re-suture of the bisected spinous processes at each decompression level. The average follow-up period was 38 months (25-53 months). The preoperative and follow-up evaluations included the original Japanese Orthopaedic Association (JOA) score, the new tentative JOA score including cervical spine function and QOL, and the visual analogue scale (VAS) of axial pain. Radiological analyses included cervical lordosis and flexion-extension range of motion (flex-ext ROM) (C2-7), and deep extensor muscle areas on MR axial images. The JOA recovery rates were statistically equivalent between two groups. The MP group demonstrated a statistically superior cervical spine function (84% vs 63%) and QOL (61% vs 45%) when compared to the CL group at final follow-up (P < 0.05). The average VAS scores at final follow-up were 2.3 and 4.9 in MP and CL groups (P < 0.05). The cervical lordosis and flex-ext ROM were statistically equivalent. The percent deep muscle area on MRI demonstrated a significant atrophy in CL group compared to that in MP group (56% vs 88%; P < 0.01). Laminoplasty employing the deep extensor muscle-preserving approach appeared to be effective in reducing the axial pain and deep muscle atrophy as well as improving cervical spine function and QOL when compared to conventional open-door laminoplasty.

Fig. 1

a–d Surgical procedure of deep extensor muscle-preserving laminoplasty. (Bottom of figure signifies the cephalad direction of the patient). a Exposure of the spinous processes in the midline, the consecutive laminae were exposed while preserving the multifidus and semispinalis cervicis muscle. The each star signifies a spinous process. b The spinous processes were vertically bisected using a surgical burr or osteotome with the preservation of extensor muscle attachments. The stay sutures were placed through the bone for the later closure. c Open-door laminoplasty was followed by the ligamentum flavum suture to the lateral paraverbral muscles. d Reconstruction of extensor muscles with tight sutures to the bisected spinous processes (arrows)

Fig. 2

a, b Representative axial MR images of deep extensor muscle after muscle-preserving laminoplasty and conventional open-door laminoplasty. a Deep extensor muscles are preserved in muscle-preserving laminoplasty. b Significant deep extensor muscle atrophy was demonstrated in conventional laminoplasty with a flat configuration of neck surface

Fig. 3

a–e A cervical OPLL patient received conventional open-door laminoplasty from C1 to C7. Note significant deep extensor muscle atrophy (box arrows): preoperative and follow-up comparison (d and e, respectively)

Fig. 4

a–e Cervical spondylotic myelopathy patient received the deep extensor muscle-preserving laminoplasty from C4 to C6. Box arrows signify the reattached spinous processes with deep extensor muscles. Note reductions in deep extensor muscle at follow-up (e) compared to preoperative image (d)