Kissing Spine Syndrome in Adolescents: Are We Missing This?

Aim and objective Low back pain (LBP) is increasingly prevalent among pediatric patients but often lacks a definitive diagnosis. Kissing Spine Syndrome (KSS), or Baastrup's Disease, is well-described in adults but understudied in children. This study characterizes the clinical and radiographic features of pediatric and adolescent patients with LBP suggestive of KSS. Methods We conducted a retrospective comparative study, wherein we reviewed 131 patients aged 10-22 years presenting with LBP to a pediatric orthopedic clinic in 2021. Inclusion criteria were lumbar spine radiographs and clinical examination. Exclusions included prior spine surgery, inadequate imaging, spondylolysis, spondylolisthesis, degenerative disc disease, and congenital anomalies. Patients were classified into a KSS group (n=23), defined by sclerosis on adjacent spinous processes, or a non-KSS group (n=108). Data were analyzed using non-parametric statistics. Results The KSS group had a higher mean age (16.5±1.8 vs 15.0±2.4 years; p=0.006) and greater female predominance (84% vs 57%; p=0.020). Pain with lumbar extension occurred in 67% of KSS and 53% of non-KSS patients (p=0.217). Patients with KSS had higher pelvic incidence (53.0°±11.5 vs 45.6°±11.3; p=0.039) and reduced interspinous distances at L2-L3 (7.5±3.3 vs 10.0±4.5 mm; p=0.015) and L4-L5 (5.1±3.1 vs 6.9±3.6 mm; p=0.013). MRI demonstrated higher frequencies of spinous process edema (22% vs 5%) and interspinous ligament edema (44% vs 24%), though differences were not statistically significant. Conclusions KSS is an identifiable cause of pediatric LBP, particularly in adolescent female subjects and patients performing extension-based activities. Key indicators include pain with lumbar extension, adjacent spinous process sclerosis, and reduced interspinous distances. MRI trends suggest early inflammatory changes, but larger studies are needed to define its diagnostic role.