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- Figure 1
Flowchart of the patient selection process.
- Figure 2
A case of a 75-year-old woman developing recurrent proximal junctional failure (R-PJF). (A) Preoperatively, her pelvic incidence (PI), lumbar lordosis (LL), and pelvic incidence–lumbar lordosis (PI–LL) were 61°, 37°, and 24°, respectively. (B) After corrective surgery, LL improved to 66° with a PI–LL of –5°. This PI–LL was overcorrected relative to her age-adjusted PI–LL target. (C) Proximal junctional failure occurred 1 month postoperatively with a proximal junctional kyphosis severity scale score of 10 points. (D) Although fusion extension surgery was performed, R-PJF occurred again. (E) Finally, the fusion was extended to T4.
Tables
Variables No R-PJF (N = 36) R-PJF (N = 24) P Total fusion levels 7.5 ± 1.8 7.0 ± 1.3 0.320 Pelvic fixation 20 (55.6%) 13 (54.2%) 1.000 Pelvic incidence (°) 52.4 ± 6.2 49.8 ± 6.9 0.070 Lumbar lordosis (°) 43.2 ± 13.8 40.9 ± 15.8 0.276 PI–LL (°) 9.1 ± 13.2 8.9 ± 14.6 0.473 Sacral slope (°) 31.8 ± 8.7 28.6 ± 8.9 0.087 Pelvic tilt (°) 19.4 ± 6.6 19.5 ± 8.0 0.491 Thoracic kyphosis (°) 25.2 ± 10.7 22.1 ± 9.5 0.124 T1 pelvic angle (°) 17.0 ± 7.7 17.0 ± 9.4 0.491 Sagittal vertical axis (mm) 19.0 ± 30.1 39.0 ± 26.5 0.005 Gravity line to hip axis (mm) –10.9 ± 32.9 –29.1 ± 38.4 0.031 Age-adjusted PI–LL 0.018 Undercorrection 8 (22.2%) 8 (33.8%) Matched correction 22 (61.1%) 6 (25.0%) Overcorrection 6 (16.7%) 10 (41.7%) Global alignment and proportion score 0.180 Proportioned 10 (27.8%) 2 (8.3%) Moderately disproportioned 10 (27.8%) 9 (37.5%) Severely disproportioned 16 (44.4%) 13 (54.2%) Scoliosis research society-Schwab PI–LL modifier 0.510 PI–LL < 10° 24 (66.7%) 13 (54.2%) PI–LL 10°–20° 5 (13.9%) 6 (25.0%) PI–LL > 20° 7 (19.4%) 5 (20.8%) Abbreviations: PI–LL, pelvic incidence–lumbar lordosis; R-PJF, recurrent proximal junctional failure.
Note: Data presented as mean ± SD or n (%). Bold P values indicate statistical significance.
Variables No R-PJF (N = 36) R-PJF (N = 24) Pa a Patient factors at the revision surgery Age, y 73.6 ± 6.9 70.5 ± 6.0 0.076 Women 31 (86.1%) 20 (83.3%) 0.768 Femoral neck BMD (T-score) –1.4 ± 1.3 –1.5 ± 1.3 0.704 Osteoporosis 7 (19.4%) 6 (25.0%) 0.609 Osteoporosis treatmenta 0.906 None 20 (55.6%) 15 (62.5%) Anabolic agents 11 (30.6%) 7 (29.1%) Antiresorptive agents 5 (13.8%) 2 (8.4%) Body mass index 27.1 ± 3.8 26.3 ± 2.8 0.392 ASA grade 2.2 ± 0.4 2.3 ± 0.4 0.807 Smoking 5 (13.8%) 2 (8.3%) 0.330 Hypertension 23 (63.9%) 18 (75.0%) 0.410 Diabetes mellitus 13 (54.2%) 11 (45.8%) 0.592 Surgical factors at the revision surgery Time from index op to revision surgery (mo) 22.7 ± 17.2 32.7 ± 22.3 0.226 Failure modes causing revision surgery 0.166 Disc and ligamentous failure 11 (30.6%) 5 (20.8%) Bony failure 19 (52.8%) 18 (75.0%) Implant/bone interface failure 6 (16.7%) 1 (4.2%) Performance of laminectomy 22 (61.1%) 9 (37.5%) 0.687 No. of fusion levels extended 4.0 ± 2.5 4.2 ± 2.7 0.840 Final UIV level 0.743 T1–T4 5 (13.9%) 3 (12.5%) T5–T8 12 (33.3%) 6 (25.0%) T9–T10 19 (52.8%) 15 (62.5%) Hounsfield unit of UIV 172.1 ± 57.1 160.5 ± 44.8 0.202 Hounsfield unit of UIV + 1 186.6 ± 55.2 167.0 ± 41.8 0.072 Uppermost screw angle (°)b –0.5 ± 3.2 1.0 ± 2.6 0.037 Hook fixation at UIV + 1 level 11 (30.6%) 5 (20.8%) 0.404 UIV cement 12 (33.3%) 2 (8.3%) 0.031 Abbreviations: ASA, American Society of Anesthesiologists; BMD, bone mineral density; R-PJF, recurrent proximal junctional failure; UIV, uppermost instrumented vertebra.
Note: Data are presented as mean ± SD or n (%). Bold P values indicate statistical significance.
↵a Anabolic agents include teriparatide, and antiresorptive agents include denosumab or bisphosphonate.
↵b Positive value represents the cranial inclination of the pedicle screw relative to the upper endplate.
Radiographic Parameters No R-PJF (N = 36) R-PJF (N = 24) P Lumbar lordosis (°) 39.2 ± 16.3 37.3 ± 16.5 0.337 Pelvic incidence–lumbar lordosis (°) 12.9 ± 15.9 14.8 ± 14.9 0.328 Sacral slope (°) 24.8 ± 1.6 23.1 ± 2.0 0.256 Pelvic tilt (°) 28.1 ± 9.9 29.1 ± 10.2 0.356 Thoracic kyphosis (°) 30.6 ± 18.7 29.1 ± 15.9 0.376 T1 pelvic angle (°) 27.8 ± 10.4 27.6 ± 5.3 0.460 Sagittal vertical axis (mm) 63.8 ± 50.2 63.1 ± 48.9 0.477 Gravity line to hip axis (mm) 0.5 ± 64.9 8.1 ± 54.4 0.318 Proximal junctional angle (°) 30.7 ± 17.0 29.1 ± 14.3 0.356 Abbreviation: R-PJF, recurrent proximal junctional failure.
PJKSS components No R-PJF (N = 36) R-PJF (N = 24) P Neurological deficit 0.107 0 pt None 5 (13.9%) 0 (0%) 2 pt Radicular pain 18 (50.0%) 11 (45.8%) 4 pt Myelopathy 13 (36.1%) 13 (54.2%) Focal pain 0.319 0 pt None 5 (13.9%) 1 (4.2%) 1 pt VAS ≤4 1 (2.8%) 0 (0%) 3 pt VAS ≥5 30 (83.3%) 23 (95.8%) Instrumentation problem 0.115 0 pt None 15 (41.7%) 6 (25.0%) 1 pt Partial fixation loss 16 (44.4%) 17 (70.8%) 2 pt Complete fixation loss 5 (13.9%) 1 (4.2%) Change in kyphosis/PLC integrity 0.731 0 pt 0°–10° 8 (22.2%) 5 (20.8%) 1 pt 10°–20° 12 (33.3%) 6 (25.0%) 2 pt > 20° or PLC failure 16 (44.4%) 13 (54.2%) UIV/UIV +1 fracture 0.026 0 pt None 12 (33.3%) 5 (20.8%) 1 pt Compression fracture 13 (36.1%) 17 (70.8%) 2 pt Burst/chance fracture 11 (30.6%) 2 (8.3%) 3 pt Translation 0 (0%) 0 (0%) Level of UIV 0.729 0 pt Thoracolumbar junction 30 (83.3%) 21 (87.5%) 1 pt Upper thoracic 6 (16.7%) 3 (12.5%) Total sum of PJKSS 8.1 ± 2.0 9.1 ± 2.1 0.023 Abbreviations: PJKSS, proximal junctional kyphosis severity scale; PLC, posterior ligamentous complex; R-PJF, recurrent proximal junctional failure; UIV, uppermost instrumented vertebrae; VAS, visual analog scale.
Note: Data presented as n (%) or mean ± SD. Bold P values indicate statistical significance.
Radiographic Parameters No R-PJF (N = 36) R-PJF (N = 24) P After revision surgery LL (°) 39.2 ± 13.8 34.9 ± 14.2 0.244 Pelvic incidence–LL (°) 13.1 ± 14.1 14.9 ± 12.9 0.311 SS (°) 30.4 ± 9.3 25.8 ± 7.7 0.025 Pelvic tilt (°) 23.9 ± 12.9 28.0 ± 15.1 0.132 TK (°) 26.5 ± 13.3 23.7 ± 13.0 0.219 TPA (°) 20.6 ± 8.0 21.4 ± 6.1 0.342 SVA (mm) 41.4 ± 35.9 35.3 ± 46.6 0.284 GL-HA (mm) –7.6 ± 37.6 –16.2 ± 55.4 0.239 PJA (°) 8.4 ± 5.2 9.0 ± 7.2 0.340 Post-pre changes Δ LL (°) –0.4 ± 6.0 –2.4 ± 6.9 0.110 Δ SS (°) –6.1 ± 11.8 –5.1 ± 7.7 0.351 Δ TK (°) –4.1 ± 9.0 –5.4 ± 8.7 0.298 Δ TPA (°) –7.2 ± 10.7 –6.2 ± 6.7 0.340 Δ SVA (mm) –22.4 ± 52.9 –27.8 ± 51.2 0.349 Δ GL-HA (mm) –8.1 ± 63.9 –24.3 ± 59.9 0.164 Δ PJA (°) –22.3 ± 18.4 –20.1 ± 15.6 0.935 Abbreviations: GL-HA, gravity line to hip axis; LL, lumbar lordosis; PJA, proximal junctional angle; R-PJF, recurrent proximal junctional failure; SS, sacral slope; SVA, sagittal vertical axis; TK, thoracic kyphosis; TPA, T1 pelvic angle.
Note: Data presented as mean ± SD. Bold P values indicate statistical significance.
- Table 6
Stepwise regression analysis of the risk factors for recurrent proximal junctional failure.
Variables P Exp (B) 95% CI At the index surgery Postoperative sagittal vertical axis (mm) 0.003 1.044 1.015–1.074 Correction relative to age-adjusted pelvic incidence–lumbar lordosis 0.027 Matched correction – Reference Undercorrection 0.088 3.633 0.717–18.408 Overcorrection 0.030 7.794 1.214–50.024 At the revision surgery Proximal junctional kyphosis severity scale score 0.045 1.415 1.007–1.989 No uppermost instrumented vertebra cement 0.037 5.494 1.105–27.027 Note: Bold P values indicate statistical significance.
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