Recovery Kinetics: Comparison of Patients Undergoing Primary or Revision Procedures for Adult Cervical Deformity Using a Novel Area Under the Curve Methodology

BACKGROUND Limited data are available to objectively define what constitutes a good versus a bad recovery for operative cervical deformity (CD) patients. Furthermore, the recovery patterns of primary versus revision procedures for CD is poorly understood. OBJECTIVE To define and compare the recovery profiles of CD patients undergoing primary or revision procedures, utilizing a novel area-under-the-curve normalization methodology. METHODS CD patients undergoing primary or revision surgery with baseline to 1-yr health-related quality of life (HRQL) scores were included. Clinical symptoms and HRQL were compared among groups (primary/revision). Normalized HRQL scores at baseline and follow-up intervals (3M, 6M, 1Y) were generated. Normalized HRQLs were plotted and area under the curve was calculated, generating one number describing overall recovery (Integrated Health State). Subanalysis identified recovery patterns through 2-yr follow-up. RESULTS Eighty-three patients were included (45 primary, 38 revision). Age (61.3 vs 61.9), gender (F: 66.7% vs 63.2%), body mass index (27.7 vs 29.3), Charlson Comorbidity Index, frailty, and osteoporosis (20% vs 13.2%) were similar between groups (P>.05). Primary patients were more preoperatively neurologically symptomatic (55.6% vs 31.6%), less sagittally malaligned (cervical sagittal vertical axis [cSVA]: 32.6 vs 46.6; T1 slope: 28.8 vs 36.8), underwent more anterior-only approaches (28.9% vs 7.9%), and less posterior-only approaches (37.8% vs 60.5%), all P<.05. Combined approaches, decompressions, osteotomies, and construct length were similar between groups (P>.05). Revisions had longer op-times (438.0 vs 734.4 min, P=.008). Following surgery, complication rate was similar between groups (66.6% vs 65.8%, P=.569). Revision patients remained more malaligned (cSVA, TS-CL; P<.05) than primary patients until 1-yr follow-up (P>.05). Normalized HRQLs determined primary patients to exhibit less neck pain (numeric rating scale [NRS]) and myelopathy (modified Japanese Orthopaedic Association) symptoms through 1-yr follow-up compared to revision patients (P<.05). These differences subsided when following patients through 2 yr (P>.05). Despite similar 2-yr HRQL outcomes, revision patients exhibited worse neck pain (NRS) Integrated Health State recovery (P<.05). CONCLUSION Despite both primary and revision patients exhibiting similar HRQL outcomes at final follow-up, revision patients were in a greater state of postoperative neck pain for a greater amount of time.