title: Can segmental mobility be increased by cervical arthroplasty?
abstract: OBJECTIVE Many reports have successfully demonstrated that cervical disc arthroplasty (CDA) can preserve range of motion after 1- or 2-level discectomy. However, few studies have addressed the extent of changes in segmental mobility after CDA or their clinical correlations. METHODS Data from consecutive patients who underwent 1-level CDA were retrospectively reviewed. Indications for surgery were medically intractable degenerative disc disease and spondylosis. Clinical outcomes, including visual analog scale (VAS)-measured neck and arm pain, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores, were analyzed. Radiographic outcomes, including C2-7 Cobb angle, the difference between pre- and postoperative C2-7 Cobb angle (ΔC2-7 Cobb angle), sagittal vertical axis (SVA), the difference between pre- and postoperative SVA (ΔSVA), segmental range of motion (ROM), and the difference between pre- and postoperative ROM (ΔROM), were assessed for their association with clinical outcomes. All patients underwent CT scanning, by which the presence and severity of heterotopic ossification (HO) were determined during the follow-up. RESULTS A total of 50 patients (mean age 45.6 ± 9.33 years) underwent a 1-level CDA (Prestige LP disc) and were followed up for a mean duration of 27.7 ± 8.76 months. All clinical outcomes, including VAS, NDI, and JOA scores, improved significantly after surgery. Preoperative and postoperative ROM values were similar (mean 9.5° vs 9.0°, p > 0.05) at each indexed level. The mean changes in segmental mobility (ΔROM) were -0.5° ± 6.13°. Patients with increased segmental mobility after surgery (ΔROM > 0°) had a lower incidence of HO and HO that was less severe (p = 0.048) than those whose ΔROM was < 0°. Segmental mobility (ROM) was significantly lower in patients with higher HO grade (p = 0.012), but it did not affect the clinical outcomes. The preoperative and postoperative C2-7 Cobb angles and SVA remained similar. The postoperative C2-7 Cobb angles, SVA, ΔC2-7 Cobb angles, and ΔSVA were not correlated to clinical outcomes after CDA. CONCLUSIONS Segmental mobility (as reflected by the mean ROM) and overall cervical alignment (i.e., mean SVA and C2-7 Cobb angle) had no significant impact on clinical outcomes after 1-level CDA. Patients with increased segmental mobility (ΔROM > 0°) had significantly less HO and similarly improved clinical outcomes than those with decreased segmental mobility (ΔROM < 0°).
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital.|School of Medicine and.
authors.forename: Hsuan-Kan
authors.initials: HK
authors.lastname: Chang
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital.|School of Medicine and.
authors.forename: Chih-Chang
authors.initials: CC
authors.lastname: Chang
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital.|School of Medicine and.
authors.forename: Tsung-Hsi
authors.initials: TH
authors.lastname: Tu
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital.|School of Medicine and.
authors.forename: Jau-Ching
authors.initials: JC
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital.|School of Medicine and.
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Huang
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital.|School of Medicine and.|Institute of Pharmacology, National Yang-Ming University; and.
authors.forename: Li-Yu
authors.initials: LY
authors.lastname: Fay
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital.|School of Medicine and.
authors.forename: Peng-Yuan
authors.initials: PY
authors.lastname: Chang
authors.affiliation: School of Medicine and.|Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Ching-Lan
authors.initials: CL
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital.|School of Medicine and.|Institute of Pharmacology, National Yang-Ming University; and.
authors.forename: Henrich
authors.initials: H
authors.lastname: Cheng
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001178:Arthroplasty / Q000379:methods*; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019547:Neck Pain / Q000209:etiology / Q000601:surgery; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D015898:Tomography Scanners, X-Ray Computed; D016896:Treatment Outcome; D064232:Visual Analog Scale
keywords: ACDF = anterior cervical discectomy and fusion; CDA = cervical disc arthroplasty; Cobb angle; DDD = degenerative disc disease; FDA = Food and Drug Administration; HO = heterotopic ossification; JOA = Japanese Orthopaedic Association; NDI = Neck Disability Index; ROM = range of motion; VAS = visual analog scale; cervical alignment; cervical disc arthroplasty; heterotopic ossification; range of motion; sagittal vertical axis; segmental mobility