Endocrine Abstracts

Patients with acromegaly (PWA) experience higher rates of falls and fall-related injuries than age-matched Canadian adults. Previous studies of standing balance revealed increased sway in PWA compared to healthy controls but failed to control for the effects of the pituitary adenoma. Therefore, the aim of the present study was to determine if acromegaly influenced the neuromuscular control of standing balance. Bipedal standing balance was evaluated in PWA (n=13) in biochemical remission and a control group of patients with non-functioning pituitary adenomas (PNA, n=13). The groups were of similar age, sex, and BMI and all participants underwent surgery to remove the pituitary adenoma. Self-reported survey data was used to compare joint pain, functional disability scores, and history of joint surgery between groups. PWA reported significantly higher back (P=0.004), hip (P=0.007), and knee (P=0.007) pain and greater functional disability of the hip (P=0.041) and knee (P=0.041) than PNA. However, the history of joint surgery did not significantly differ between groups. Bipedal standing balance trials were repeated with eyes open, and eyes closed. Bipedal centre of pressure (COP) was measured using two AMTI force plates with one underneath each foot. Centre of mass (COM) was measured using a 14 body segment model with anatomical 3D positions recorded using a 14-camera OptiTrack motion capture system. The force plates and motion capture systems were synchronized and sampled at 200 Hz. Primary outcome measures included COP 95% prediction ellipse area and anteroposterior (AP) and mediolateral (ml) components of COP range, COP mean velocity, COP median frequency, root mean square (RMS) difference between COP and COM, cross-correlation between COP and COM, and time lag between COP and COM. PWA exhibited significantly greater RMS difference of COP and COM than PNA in both the AP (P=0.042) and ml (P=0.006) axes. No other balance measures were significantly different between the groups. There was no significant interaction between vision and acromegaly for any of the balance outcome measures. In conclusion, the larger RMS difference between COP and COM may indicate impaired sagittal plane ankle stiffness and impaired frontal plane hip mechanics in PWA.