Incidence and Risk Factors for Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis After Correction Surgery: A Meta-Analysis.

OBJECTIVE: To evaluate the incidence and risk factors associated with proximal junctional kyphosis (PJK) in patients with adolescent idiopathic scoliosis (AIS) after correction surgery. METHODS: PubMed, Embase, and Cochrane Library were searched from inception until August 2018 to obtain relevant studies. After study selection and data extraction, statistical analysis was performed with RevMan 5.3. The odds ratios (ORs) and weight mean differences (WMDs) with 95% confidence intervals (CIs) for all available factors were analyzed using fixed or random effects models. RESULTS: A total of 7 studies were included in this meta-analysis. The overall incidence of PJK in AIS was 14% (95% CI, 8%-20%). Among the potential risk factors, proximal implants with screws (OR, 1.64; 95% CI, 1.13-2.39; P = 0.010), instrumentation types with all screws (OR, 1.78; 95% CI, 1.19-2.67; P = 0.005), larger preoperative thoracic kyphosis (TK) (WMD, 7.50; 95% CI, 5.75-9.26; P < 0.001), larger preoperative lumbar lordosis (LL) (WMD, 4.85; 95% CI, 2.79-6.92; P < 0.001), larger postoperative LL (WMD, 2.00; 95% CI, 0.09-3.91; P = 0.040), greater change in TK (WMD, -6.75; 95% CI, -9.72 to -3.78; P < 0.001), and greater change in LL (WMD, -3.26; 95% CI, -5.40 to -1.12; P = 0.003) were identified as risk factors for PJK. CONCLUSIONS: The incidence of PJK in patients with AIS was 14%. Proximal implants with screws and instrumentation types with all screws were significantly associated with increased occurrence of PJK. Larger preoperative TK, larger preoperative LL, larger postoperative LL, greater TK change, and greater LL change were also identified as risk factors for PJK in AIS after correction surgery.

Postoperative Cervical Sagittal Realignment Improves Patient-Reported Outcomes in Chronic Atlantoaxial Anterior Dislocation.

BACKGROUND: Chronic atlantoaxial anterior dislocation (AAD) not only results in myelopathy, but dislocation-related kyphosis also results in cervical malalignment, which permanently affects neck function and patient-reported outcomes (PROs). OBJECTIVE: To investigate the effect of kyphotic correction on realigning cervical spine and independent cervical alignment parameters, which may be correlated with an improvement of PROs. METHODS: The study included 21 patients with chronic AAD-related kyphosis who underwent C1-2 reduction and correction surgery. Radiographic parameters were measured to assess cervical realignment preoperatively and postoperatively. Neck disability index (NDI), short form 12 physical component summary (SF-12 PCS), and Japanese Orthopaedic Association (JOA) scores were recorded to reveal changes in PROs. The independent parameters correlated with the improvements of PROs were analyzed. RESULTS: Of the radiographic parameters, the C1-2 Cobb angle, the C2-7 Cobb angle, thoracic inlet angle, cervical tilt, and T1 slope were significantly changed from -4.0° ± 16.2°, -29.2° ± 11.2°, 73.1° ± 13.3°, 30.4° ± 8.5°, and 29.1° ± 8.8° preoperatively to -13.5° ± 8.1° (P = .005), -18.0° ± 12.0° (P < .001), 67.1° ± 11.6° (P = .042), 23.1° ± 10.3° (P = .007), and 24.0° ± 7.0° (P = .011) at last follow-up, respectively. NDI, JOA, and SF-12 PCS scores were significantly improved postoperatively. The C1-2 Cobb angle was an independent parameter correlated with the improvements in SF-12 PCS, NDI, and JOA scores. CONCLUSION: Correction and reduction surgery can realign cervical spine in chronic AAD patients. The C1-2 Cobb angle was an independent parameter correlated with the improvements of PROs.