Acromegaly is the result of a pituitary adenoma development which in turn leads to an increase in growth hormone (GH) and insulin-like growth factor-1 (IGF-1). Apart from swelling of the soft tissue in the hands and feet, cardiac hypertrophy and metabolic symptoms, this disorder is also associated with osteoarticular complications. Although there have been earlier case reports implying association between acromegaly and spinal ligament ossification, these were not conclusive nor were further investigated. A recent manuscript, published recently by Hoshino et al. in Bone Reports, went on to investigate the incidence of ossification of the spinal ligaments in patients with acromegaly.
Following approval from the institutional review board of the University of Tokyo, the study recruited 10 consecutive acromegaly patients who visited the University of Tokyo Hospital from December 2020 to December 2021. After diagnosis of acromegaly, patients underwent spinal CT to explore comorbidity of spinal ligament ossification. CT images were evaluated by two experienced orthopaedic surgeons, who also calculated the posterior/anterior/yellow (flavum) ligament indices (OP/OA/OF indices). The total ossification index (OS index) was calculated by the sum of the OA, OP and OF indices. In the present study, the OS index was used as indicative for the severity of spinal ligament ossification in each patient.
Findings showed that 5 out of 10 patients had ossification of the spinal ligaments. In particular, two patients had ossification of the anterior longitudinal ligament (OALL) and ossification of the ligamentum flavum (OLF) in addition to ossification of the posterior longitudinal ligament (OPLL). The remaining three patients had both OALL and OLF. There was no significant correlation between the OS index and GH or IGF-1. Body mass index was significantly higher in the patients with spinal ligament ossification, but there were no significant differences in age, sex, serum phosphate, albumin-adjusted calcium, GH, standard deviation of IGF-1, or presence of diabetes mellitus between the patients with or without ossification of the spinal ligaments.
Although this study had a rather small sample size, it was the first to report high prevalence of spinal ossification in acromegaly patients. In view of these findings, authors suggested that acromegaly patients should be tested to confirm, or rule out, spinal ossification but they also acknowledged the need of larger-scale prospective studies to clarify whether there is significant association between acromegaly and ossification of the spinal ligaments.