Fractures in Hereditary Neuromuscular Disorders: Frequency, Risk Factors, and Implications

Abstract

Background: Hereditary neuromuscular disorders (NMD) are associated with compromised bone health and elevated fracture risk, though data are largely lacking.

Objective: This study aimed to assess the prevalence and risk factors of fractures in hereditary NMD.

Methods: We conducted a retrospective study in a cohort of adult patients with diverse hereditary NMD, using data from electronic medical records.

Results: Among 469 patients, 505 fractures were recorded, with 5.5% of patients experiencing a fracture within the past year. In the 10 years preceding study inclusion, 31.1% of all patients sustained at least one fracture. The fracture rate was 47.3/1000 patient-years. Fracture incidence was highest in the second decade of life and the first five years after symptom onset. Fracture recurrence occurred in 25.6% over the next two years. Fractures were most prevalent in patients with Duchenne muscular dystrophy, myotonic dystrophy type 1/2, and spinal muscular atrophy. Patients with Vignos scale 5-6 had the highest fracture risk. Major osteoporotic fractures accounted for 28.6%, and 71.3% were caused by low-energy trauma. Long-term complications of a fracture were present in 44.2%, with 9.0% losing ambulation. Osteoporosis was confirmed in 47.5% of DXA scans. In patients with a normal DXA scan, 66.7% experienced a subsequent fracture. Hip T-scores declined with increasing Vignos scale (r = -0.27, p = 0.001). Fracture risk factors included glucocorticoid use, alcohol abuse, recent falls, and previous emergency visits for falls (all p < 0.05).

Conclusion: This cohort exhibited a high prevalence of fractures and osteoporosis, emphasizing the need for regular bone health assessment and fracture prevention in hereditary NMD patients.

Keywords: DXA scan; bone health; fall; muscular dystrophy; osteoporosis.

FIGURE 1

Distribution of mobility of the patient cohort according to the Vignos scale and use of walking aid. Bar chart presenting (A) the frequency of patients with mobility limitations based on the Vignos scale (1–9); and (B) the level of support provided by the patients' walking aids, for the total cohort and the different neuromuscular diseases separately. The number of patients per disease group are displayed at the top of the figure. Disease abbreviations are explained in the Methods section.

FIGURE 2

Prevalence of falls and fractures in hereditary neuromuscular diseases. Bar chart showing the percentage of patients (A) categorized by neuromuscular disorder, and (B) by Vignos scale for the following outcomes: Patients with at least one fall during the past 12 months (blue bar), patients with a fracture due to a fall during the past 12 months (green bar), and patients with a fracture during the past 12 months (red bar).

FIGURE 3

Distribution of recorded fractures by age and onset of neuromuscular symptoms. The bar chart (A) illustrates the number of fractures recorded in five‐year intervals, categorized by the years before (light gray bars) and after (dark gray bars) the onset of neuromuscular symptoms, which is indicated by a dotted vertical line. The second bar and third chart displays the age distribution of fractures at the time of occurrence, (B) for all patients and (C) when excluding DMD and SMA patients.

FIGURE 4

Fractures by location and mechanism. Bar chart depicting (A) the distribution of fracture sites among the 505 recorded fractures during the patients' lifetimes, grouped by neuromuscular disorder. The total number of recorded fractures per disease group are displayed at the top of the figure. Percentages indicated in white in the bars represent the fractures commonly associated with diminished bone health, i.e. major osteoporotic fractures, in the lower arm/wrist, vertebra/backbone, shoulder and hip. (B) Bar chart illustrating the mechanism of fractures, for the total cohort and for each neuromuscular disorder separately.

FIGURE 5

Results of DXA scans categorized by Vignos scale. Bar chart illustrating the mean and standard deviation of T‐scores from 101 DXA scans performed in the total patient cohort. The first graph (A) shows the results for the lumbar spine and hip, with light gray representing patients with a Vignos scale of 1–8, and dark gray patients with a Vignos scale of 9. The second (B) and third (C) scatter plot display the mean T‐scores and standard deviations for the lumbar spine and hip, respectively, grouped by individual Vignos scale grades. Vignos scale 7 and 8 were not included.