Diagnosing a calcaneal stress fracture requires a high index of suspicion because the symptoms often resemble more common causes of heel pain such as plantar fasciosis. Unlike an acute fracture, there is usually no history of a fall or major injury. Instead, the diagnosis is based on recognising the pattern of symptoms, identifying risk factors and confirming the injury with appropriate imaging.
The assessment begins with a detailed history. Patients are asked when the pain started, how it has progressed and whether there has been a recent change in activity levels. A sudden increase in running distance, military training, prolonged walking, sporting activity or occupational standing often provides an important clue. It is equally important to identify medical risk factors such as osteoporosis, vitamin D deficiency, previous stress fractures, eating disorders, menstrual irregularities or medications that affect bone health.
The pattern of pain is also highly informative. Patients with a calcaneal stress fracture typically report pain that worsens the longer they remain active. Initially the pain may only occur during exercise, but as the injury progresses it often develops during normal walking and eventually at rest. This differs from the classic presentation of plantar fasciosis, where pain is usually most severe during the first few steps after getting out of bed.
Clinical examination focuses on identifying the structures responsible for the pain. Tenderness is often present within the body of the calcaneus rather than only at the attachment of the plantar fascia. Compression of the heel from the sides, commonly called the calcaneal squeeze test, may reproduce symptoms because it places pressure through the injured bone. Gait assessment, foot posture and lower limb biomechanics are also evaluated because they may have contributed to the development of the stress injury.
Diagnostic ultrasound is frequently performed as part of the assessment of chronic heel pain because it provides excellent visualisation of the plantar fascia, tendons and surrounding soft tissues. Ultrasound may demonstrate plantar fasciosis or other associated pathology, but it cannot reliably diagnose a stress fracture within the calcaneus. A normal ultrasound therefore does not exclude a bone stress injury.
When a stress fracture is suspected, MRI is the investigation of choice. MRI is highly sensitive and can detect bone marrow oedema before a fracture line becomes visible. In many patients, MRI identifies a stress reaction at an early stage, allowing treatment to begin before a complete stress fracture develops. Typical MRI findings include bone marrow oedema within the calcaneus and, in more advanced cases, a visible fracture line extending through the trabecular bone.
Plain X-rays are usually the first imaging investigation requested in primary care because they are readily available and inexpensive. However, early stress fractures are frequently invisible on X-ray because insufficient bone healing has occurred to produce radiographic changes. A normal X-ray therefore should never reassure clinicians if the clinical suspicion for a stress fracture remains high.
Computed tomography (CT) is occasionally used when further definition of the fracture anatomy is required or when MRI is unavailable. However, CT is less sensitive than MRI for detecting early bone stress reactions because it primarily demonstrates structural bone changes rather than bone marrow oedema.
One of the most important aspects of diagnosis is excluding other causes of heel pain. Calcaneal bone marrow oedema, plantar fasciosis, Baxter's nerve entrapment, heel fat pad syndrome, inflammatory arthritis, infection and, rarely, bone tumours may all produce similar symptoms. MRI is particularly valuable because it evaluates both the bone and surrounding soft tissues during the same examination.
Early diagnosis significantly improves outcomes. Identifying a stress reaction before a complete fracture develops allows activity modification, appropriate protection and gradual rehabilitation while avoiding progression of the injury. Continuing to train or work through pain greatly increases the risk of delayed healing, fracture propagation and prolonged recovery.
The diagnosis of a calcaneal stress fracture therefore relies on combining the patient's history, physical examination and appropriate imaging rather than depending on a single test. This systematic approach ensures that treatment is directed at the true cause of the heel pain before the injury becomes more severe.