Parkinson’s disease (PD) significantly increases the risk of fractures, especially hip and other non-vertebral fractures, due to a combination of factors related to the disease’s effects on the body. People with PD have about twice the risk of hip fractures and nearly double the risk of fractures in other bones compared to those without the disease. This elevated fracture risk arises from several interconnected causes intrinsic to PD as well as secondary complications.
One major contributor is **postural instability and gait disturbances** caused by the progressive loss of motor control in PD. The disease leads to symptoms like tremors, rigidity, slowness of movement, and impaired balance. These motor impairments make falls much more frequent and severe. In fact, over 40% of individuals with PD experience recurrent falls. Each fall carries a risk of bone injury, and repeated falls increase the cumulative fracture risk.
Another key factor is **reduced bone mineral density (BMD)**, often linked to PD-related osteoporosis. Osteoporosis is a condition where bones become weak and brittle, making them more susceptible to fractures even from minor trauma. PD patients frequently have lower BMD due to a combination of reduced mobility, nutritional deficiencies, and possibly disease-related metabolic changes. Vitamin D deficiency, common in PD, further worsens bone health since vitamin D is essential for calcium absorption and bone strength.
Long-term use of certain **medications for PD** may also negatively affect bone health. Some drugs can influence calcium metabolism or cause side effects like dizziness and orthostatic hypotension (a drop in blood pressure upon standing), which increase fall risk. Additionally, muscle weakness and rigidity reduce the protective reflexes that normally help prevent falls or reduce their impact.
Cognitive impairment and other non-motor symptoms of PD, such as slowed reaction times and impaired judgment, can contribute to unsafe movements and poor hazard recognition, further increasing the likelihood of falls and fractures. The combination of motor and cognitive decline creates a dangerous environment for bone injuries.
When fractures do occur, especially hip fractures, PD patients face additional challenges. Surgical treatments like total hip arthroplasty (THA) are complicated by PD-related muscle weakness, impaired motor control, and cognitive issues, which increase the risk of postoperative complications such as joint dislocation. Rehabilitation after fractures is also more difficult due to the progressive nature of PD, often leading to prolonged immobility and further bone loss.
Physical activity, particularly walking at a brisk pace, is known to help maintain bone strength and reduce fracture risk in the general population. However, PD patients often experience reduced mobility and slower walking speeds, which may limit this protective effect. Encouraging safe, supervised physical activity tailored to PD patients can help mitigate bone loss and improve balance, potentially lowering fracture risk.
In summary, Parkinson’s disease affects fracture risk through a complex interplay of increased falls due to motor symptoms, decreased bone density from osteoporosis and vitamin D deficiency, medication side effects, and cognitive decline. These factors combine to make fractures, especially hip fractures, a common and serious complication in PD, requiring careful management of bone health, fall prevention strategies, and tailored rehabilitation approaches.
