A common injury in endurance runners and military recruits is bone stress. This bone injury occurs when overload to the bone from excessive activity, such as running, exceeds the ability of the bone to recover. Stress fracture can occur on the neck or shaft of the long bone of the leg, called the femur. This blog will discuss the typical presentation of a femoral shaft stress fracture and how we diagnose and manage it.
What is a femoral shaft stress fracture?
Generally, a femoral shaft stress fracture is defined as the weakening or fatigue of the middle part of the femur between the neck (near the hip joint) and the bottom of the femur (near the knee joint).
Femur stress fracture symptoms
As bone stress occurs in the middle or shaft of the femur, athletes present with vague pain in the front or inner thigh. Sometimes, this pain can move to the hip or knee, which can be confused with other injuries such as hip arthritis or meniscal tear of the knee. One study found anterior thigh pain in 50% of patients, while hip and groin pain was found in 27% and 8%, respectively.
Generally, pain is aggravated during and after impact activities such as walking or running. As bone stress worsens, pain can occur at rest and at night while sleeping. In severe cases, patients find it hard to walk and can limp.
Runners with a femur stress fracture will often have risk factors for bone stress, including:
- A sudden increase in running training volume and intensity
- Previous stress fractures
- Features that affect bone health, such as caloric restriction, Vit D deficiency and a history of abnormal or an absence of menstruation in females
Diagnosis of femoral shaft stress fracture
Any endurance runner with running-related pain should be assessed to exclude bone stress. Examining both the hip and knee is vital to exclude problems in these joints.
Features on clinical examination that make bone stress of the femoral shaft more likely include pain with hopping and pin-point tenderness on palpation of the shaft of the femur.
Femoral stress fracture test
A particular test called the ‘fulcrum’ or ‘hangman’ test is often positive. While sitting on the examining bed’s edge with your mid-thigh on the edge, your doctor will apply pressure on the bottom of your thigh. Pain with this test increases the likelihood of having bone stress in the femoral shaft.
If we suspect a femur stress fracture, imaging is required.
An X-ray can show bone cortex thickening and a fracture line. However, most X-rays will be normal in the early stages. In one study, X-ray showed changes in only 24% of runners with a femur stress fracture.
Generally, we suggest an MRI scan showing swelling in the bone marrow and cortex. In more advanced cases, we see a fracture line through the cortex.
Femoral stress fracture vs. quad strain
Sometimes, it can be challenging to differentiate a femoral stress fracture from a quad strain.
Often, a quad strain presents with localised tenderness in the quadriceps muscle and pain with resisted quads testing, such as resisted knee extension. Also, patients with a quads strain often don’t limp or have pain with a single hop.
Femoral stress fracture treatment
Once diagnosed, we recommend complete rest from impact activity – such as walking and running. If you’re limping, partial weight-bearing with crutches for 3-4 weeks will aid recovery. Crutches are stopped once the pain settles.
Non-impact activities such as swimming, upper body ergometry, and upper body strength training can be started immediately to maintain fitness. Once pain-free and off crutches, you can add cycling to non-impact activity. With time, other activities can be added, including gentle walking and lower body weights. You should consult a rehab specialist to supervise a strength training program to improve your lower body and hip strength. Once you can walk and hop without pain, you can perform a progressive walk/run programme supervised by your therapist. This graduated walk/run programme will often take 4-6 weeks.
Using an anti-G anti-gravity treadmill can accelerate your return to walking and running. It would be best to speak to your therapist about using an anti-gravity machine for rehab.
Generally, most runners return to full training in 4-5 months, although timeframes can vary depending on the patient and the severity of the stress fracture of the femur.
Frequently asked questions about femur stress fracture:
Can you bike with a femoral stress fracture?
Yes, you can bike with a femoral stress fracture. However, we suggest you begin cycling only when you have stopped limping and can walk without pain.
Can you walk on a fractured femur?
Yes, in the early stages, patients can often walk without pain. However, as the stress fracture worsens, walking becomes difficult, and limping is common.
Progressive walking is added during the second part of the rehab phase before the start of a running programme.
Is shockwave a possible treatment for a femoral stress fracture?
Yes. Recent evidence suggests that a type of shockwave called focused shockwave may help with bony healing in stress fractures. Generally, we recommend 3-5 sessions of high-energy-focused shockwave therapy in addition to other treatments. Sometimes, additional shockwave therapy is performed during the return to running or sport.
Final word from Sportdoctorlondon about femoral shaft stress fracture
Femoral shaft stress fractures are common in runners and military recruits. Any runner with pain at the front of the thigh, groin or upper knee needs assessment to exclude bone stress.
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