Knee replacement surgery involves replacing damaged parts of the knee joint with artificial components, typically made from metal and plastic. This procedure aims to alleviate pain and restore mobility for individuals with severe knee arthritis or injury. A common concern among patients is the durability of these implants, particularly whether they can be damaged or “broken” by a fall. While designed for strength and longevity, understanding their interaction with natural bone and fall impacts is important.
Understanding Knee Replacement Durability
Modern knee replacements are engineered to withstand significant daily stresses and loads, making them highly durable. Components are often crafted from metal alloys like cobalt-chromium and titanium, known for their strength and corrosion resistance, and high-density polyethylene, a specialized plastic providing a smooth, low-friction surface. These materials are selected for biocompatibility and ability to sustain mechanical stress. While designed to last many years, often between 15 to 20 years or more, they are not entirely indestructible. Implant longevity is influenced by factors such as the patient’s activity level and body weight.
How Falls Can Affect a Knee Replacement
While the artificial implant components themselves are highly robust and rarely “break” from a fall, a significant impact can still lead to serious complications. The most common issue arising from a fall is a periprosthetic fracture, which is a break in the bone surrounding the knee replacement components. These fractures can occur in the thigh bone (femur), shin bone (tibia), or kneecap (patella), with the femur being the most frequently affected. The bone often fractures before the metal or plastic components of the implant.
Another potential consequence is implant loosening, where the artificial components detach from the underlying bone. The force of a fall can disrupt the bond between the implant and the bone, regardless of whether it was secured with cement or designed for bone ingrowth. This loosening can cause pain and instability in the knee joint. Less common from a single fall, severe trauma or repeated impacts can damage the plastic insert or deform a metal component.
Factors Influencing Damage Risk
Several factors can influence the likelihood and severity of damage to a knee replacement from a fall. Bone quality plays a significant role, as individuals with osteoporosis or lower bone density are at an increased risk of periprosthetic fractures because their bones are more fragile. The type and severity of the fall also matter; high-impact falls, such as those from a height, or falls involving twisting motions, pose a greater risk of injury.
A patient’s age and overall health contribute to the risk. Older individuals or those with certain medical conditions, such as muscle weakness or poor vision, may have weaker bones or slower reflexes, increasing their susceptibility to falls and subsequent damage. The time since surgery is another factor; falls early in recovery (before full healing) or very late (after significant implant wear) can lead to complications. Specific implant designs or fixation methods can affect how they respond to extreme forces.
Steps to Take After a Fall
Experiencing a fall after knee replacement surgery requires immediate attention to assess for potential damage. The first step is to remain calm and assess the situation from where you are. Check for any immediate pain, swelling, or visible deformity around the operated knee. It is important to avoid putting weight on the affected leg if there is significant pain or an inability to move the limb.
If you cannot get up safely on your own, seek assistance from someone nearby or call for emergency help. Contacting your orthopedic surgeon or going to an emergency room is advisable, especially if symptoms are severe or you cannot bear weight. Diagnostic imaging, such as X-rays, will determine if any damage has occurred to the implant or surrounding bone. Even if pain is mild, prompt evaluation is important to rule out damage.