Impact of Adjacent Muscular Anatomic Preservation on Proximal Junctional Kyphosis and Failure

Surgical intervention is a cornerstone of adult spinal deformity (ASD) management. However, there remain burdens from complications, including proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). Posterior anatomic preservation at the uppermost instrumented vertebra has emerged as an accessible approach to potentially reduce PJK/PJF risk.

We assembled an institutional cohort of patients with ASD evaluated between 2017 and 2022 who had spinal fusion performed with a modified subperiosteal dissection at and immediately below the uppermost instrumented vertebra. Through a meta-analysis with a random-effects model, we compared our incidence of PJK/PJF against other prophylactic interventions.

Ninety patients were identified, (median age, 64 years; average follow-up, 19 months). Most had scoliosis and/or spinal stenosis with a median of 8 levels fused (40% revision cases). 6.7% and 3.3% of patients developed PJK and PJF, respectively, with the most common clinical correlate being a minor neurologic deficit such as numbness (37.8%). PJK/PJF and non-PJK/PJF patients had similar postoperative complication profiles. Radiographic parameters varied: the PJK/PJF cohort had greater preoperative pelvic incidence/pelvic tilt and postoperative pelvic incidence-lumbar lordosis mismatch as well as smaller operative correction of the thoracolumbar Cobb angle. In the literature, prophylactic interventions broadly reduced the incidence of PJK/PJF, with a pooled estimate of 19% compared with 36% in patients who did not receive any additional intervention.

Preservation of posterior anatomic structures likely has a role in reducing the rate of PJK/PJF. Linking radiographic parameters to PJK/PJF and studying techniques that keep posterior structures intact may be steps toward improving ASD correction outcomes.