A hip stress fracture is an overuse injury where a bone develops a microscopic break from repeated stress, rather than a single traumatic event like a fall. Unlike a sudden, complete break, this injury starts as a tiny crack that grows when the bone’s natural repair process cannot keep up with the constant, excessive force being placed upon it. A stress fracture in the hip often indicates an imbalance between training load and bone health. Early identification is important to avoid complications that can lead to long-term problems with the hip joint.
Defining the Injury and Common Locations
A hip stress fracture most frequently occurs in the femoral neck, the short, thinner segment of the thigh bone (femur) connecting the ball of the hip joint to the main shaft. This area is under significant mechanical load even during simple activities like standing, with forces multiplying during running. The pubic rami, which are part of the pelvis, are another common location for stress fractures in the hip region, particularly in long-distance runners.
Stress fractures in the femoral neck are categorized based on their location, which dictates the severity and treatment approach. A compression-sided fracture occurs on the inferior (lower, inside) aspect of the neck, where the bone is under compressive load. These are generally considered lower-risk injuries that often heal well with rest and non-weight bearing.
A tension-sided fracture occurs on the superior (upper, outside) aspect of the femoral neck, where the bone is pulled apart during activity. This type is considered high-risk because the pulling forces make the fracture unstable and prone to widening or displacing completely. Displacement can severely compromise the blood supply to the femoral head, potentially leading to bone death, a complication known as avascular necrosis. Immediate diagnosis and treatment of tension-sided fractures are necessary.
Causes and Who Is At Risk
The underlying cause of a hip stress fracture is a repetitive overload that disrupts the normal cycle of bone remodeling. A frequent factor is the abrupt or excessive increase in the intensity, duration, or volume of physical activity, often referred to as a training error. This sudden change does not allow the bone tissue enough time to adapt and strengthen in response to the new demands.
Biomechanical factors, such as an improper gait or running form, can also contribute by creating abnormal stress concentrations on the bone. The injury is prevalent in high-impact populations, including long-distance runners and military recruits who undergo rapid and strenuous physical conditioning. Track and field athletes are another group with a high incidence of stress fractures.
Inadequate nutritional habits and low bone mineral density significantly increase vulnerability to these injuries. Conditions like Relative Energy Deficiency in Sport (RED-S), which involves insufficient caloric intake relative to energy expenditure, are directly linked to poor bone health and increased stress fracture risk. This energy imbalance can lead to hormonal irregularities, such as low estrogen levels in females, which impair the activity of bone-building cells, making the skeleton structurally weaker.
Recognizing Symptoms and Seeking Diagnosis
The pain associated with a hip stress fracture typically begins subtly, often described as a mild ache in the groin area that is only noticeable during activity. Initially, the discomfort may disappear quickly with rest, but as the fracture progresses, the pain becomes more persistent and intense, eventually occurring during normal walking or even while resting. A tell-tale sign is pain that worsens with weight-bearing activities like running or jumping.
The diagnostic process begins with a physical examination, which may include tests like the single-leg hop test, where a sharp increase in pain suggests a positive result. While standard X-rays are often the first imaging test ordered, they frequently appear normal in the early stages because the hairline crack is too small to be visible. This limitation means that stress fractures are often missed early on.
For a definitive diagnosis, advanced imaging is usually necessary, with Magnetic Resonance Imaging (MRI) being the most sensitive technique. An MRI can detect the bone’s inflammatory response to the stress injury even before a visible fracture line appears on an X-ray. A bone scan is another reliable option that can confirm the diagnosis by showing increased metabolic activity in the injured area.
Treatment Protocols and Recovery Timelines
Treatment for a hip stress fracture is highly dependent on the location and type of injury, specifically whether it is a lower-risk compression-sided or a higher-risk tension-sided fracture. Lower-risk compression-sided fractures are generally managed non-surgically, involving a period of strict rest and protected weight-bearing. Patients are typically required to use crutches for non-weight-bearing movement for about six weeks to remove mechanical stress from the bone.
Higher-risk tension-sided fractures, or those where the crack involves more than 50% of the femoral neck width, typically require surgical intervention. The surgery usually involves internal fixation, such as placing cannulated screws across the fracture site to stabilize the bone and prevent displacement. This stabilization protects the blood supply to the femoral head and minimizes the risk of serious complications.
Following the initial period of non-weight-bearing (six to twelve weeks), a gradual return to activity begins. Full recovery and a return to high-impact sports typically take between three to six months, and sometimes up to a year. Physical therapy is a necessary component of recovery, focusing on restoring strength, flexibility, and addressing underlying biomechanical issues to prevent recurrence. Addressing nutritional deficiencies, particularly calcium and Vitamin D levels, is also an ongoing component of the treatment plan.