Characteristics of Adult-Onset Acute Lumbar Spondylolysis Treated Conservatively.

Introduction: Lumbar spondylolysis typically arises during adolescence, whereas its onset in adulthood is rare. Several studies have reported incidentally identified terminal-stage spondylolysis in adults, but only one case series has investigated acute lumbar spondylolysis lesions with bone marrow edema in adults. Methods: We retrospectively investigated lumbar spondylolysis in patients aged 18 years or older. Age at diagnosis, sex, competitive sporting level, and competitive sporting discipline were investigated in each patient. The level of the affected vertebra, pathological stage, bone union, and treatment period were analyzed for each lesion. Results: The study included nine patients (eight males and one female), aged 18-22 years old, with 14 acute lumbar spondylolysis lesions. Four patients were soccer players (two professionals, and two amateurs), four were amateur track and field athletes, and one was an amateur basketball player. The affected vertebral levels were L3 in two lesions, L4 in seven lesions, and L5 in five lesions. The pathological stage was pre-lysis stage in two lesions, early stage in eight lesions, and progressive stage in four lesions. Ten lesions achieved bone union with conservative therapy. The average treatment period was 84.7 days. Conclusions: The adult-onset lumbar spondylolysis patients were young, up to their early 20s, and generally professional sportspeople performing at an elite level. Most of them were performing a sport that has been reported to have a high risk of causing lumbar spondylolysis. L4 was the most affected vertebral level in contrast to L5, which has been reported in adolescent lumbar spondylolysis. Bone union was achieved for most lesions with conservative therapy.