Risk factors and potential prevention strategies for PJK and PJF.
| Risk Factors | Prevention Techniques |
| Surgical | |
| Disruption of posterior soft tissues | Meticulous dissection at UIV and care to protect facet capsule of the level above |
| Rigidity of instrumentation | Use of hooks vs screws at proximal level, not engaging all screw threads proximally, use of transition rods and tethers |
| Choice of vertebral levels | UIV in the lower thoracic spine increases the risk of failure and vertebral fracture, UIV in the upper thoracic spine may increase the risk of junctional kyphosis, and lower instrumented vertebra to the sacrum/pelvis may increase the risk of PJK/PJF |
| Choice of approach | Avoid combined anterior-posterior approaches if feasible |
| Degree of correction: high SVA correction, increased correction of lumbar lordosis | Optimize global sagittal alignment, SVA of 0 cm may not be optimal for all patients, and PJK may be a compensatory mechanism for overcorrection; consider age-adjusted alignment targets, “ideal” Roussouly type, Global Alignment and Proportion Score |
| UIV loading | Under-loading of the UIV (decreased bending moment) associated with PJK/PJF |
| Radiographic | |
| Increased preoperative thoracic kyphosis | Nonmodifiable |
| Increased preoperative proximal junctional angle (>5°) | Ensure the construct includes any levels with junctional kyphosis >5° |
| Patient Specific | |
| Advanced age (>55 y) | Nonmodifiable |
| Body mass index | Encourage weight loss and nutrition counseling |
| Osteopenia/osteoporosis | Vertebral augmentation and preoperative optimization (consider interventions such as intermittent teriparatide treatment) |
| Lower muscularity and fatty degeneration in the thoracolumbar region | Consider UIV in the upper rather than lower thoracic in these patients |
| Higher preoperative thoracic spine flexibility associated with PJK | Obtain preoperative supine radiographs to identify patients at risk of thoracic spine flattening during positioning |
Abbreviations: PJF, proximal junctional failure; PJK, proximal junctional kyphosis; SVA, sagittal vertical axis; UIV, upper instrumented vertebra.
Note: Modified from: Kim HJ, Iyer S. Proximal junctional kyphosis. J Am Acad Orthop Surg. 2016;24(5):318–326. doi:10.5435/JAAOS-D-14-00393.