A leg length difference can cause changes in the way we move. To move efficiently and prevent injury, it is preferred to have symmetric alignment of our muscles and bones. This causes less stress and fatigue to our bodies.
Leg length differences are common, with the majority of people having a difference of less than 1.1cm. They are usually able to easily compensate for this.
As we move from one leg to the other as we walk, our bodies constantly have a shifting centre of gravity. This moves the force from one leg to the other. If we have a leg length difference, it means that the pressure may be higher through one leg. This can cause an array of injuries.
When does a leg length difference cause an injury?
The likelihood of developing an injury due to a leg length difference is based on how much force is going through the legs.
So in general, an injury is more likely in the case of
- A large difference between the length of two legs
- High impact activities eg. Running
There are 2 main types of leg length difference – structural and functional. A structural difference is caused by the length of the leg bones being different. Whereas a functional leg length difference is due to the body compensating for an injury or other alignment issue somewhere in the body.
How do we measure a limb length difference?
There are 3 main ways to clinically measure a limb length difference.
- CT Scan: At Performance Podiatry we often refer for a CT leg length scan to measure the length of the thigh and shin bones. We have a special relationship with a radiology clinic who allow our clients to have these bulk billed through Medicare. This CT scan is a single image from the pelvis to the feet. It is highly accurate and low radiation (approximately 1/7 of the radiation of a plain xray).
- Tape Measure: This method involves your podiatrist measuring the length of the legs from the hips to ankles. It can be unreliable as it does not account for any rotation from the hips or soft tissues contracting due to an injury.
- Heel Raises: By adding a heel raise to the shorter leg when standing, your therapist can monitor if the hips level out. This usually means that there is a functional or structural leg length difference. Unfortunately this method does not differentiate between which type of leg length difference is present.
What are the signs of a leg length discrepancy?
- Lower back pain
- Bending one knee or leaning to one hip while standing
- One foot may be flat and the other high arched
- Stress fracture
- Disc herniation
- Hip and knee pain (+ OA), PFP syndrome
- Piriformis syndrome
- ITB syndrome
- Hip bursitis
- Plantar fasciitis
- Posterior tibial stress syndrome (shin splints)
- Contracture of the Achilles tendon
- Metatarsalgia (pain in ball of foot)
How do we treat a leg length difference?
First we need to address if the difference is structural or functional. Your podiatrist will refer you for the appropriate scans to determine this in your biomechanical assessment. If the difference lies between the length of the bones, we must treat that by adding a full foot raise inside or outside of the shoe. A heel raise can also be used, but this is not our preference, as it means that one foot is in a downward facing position compared to the other foot. This can cause problems of its own.
If the difference between the legs is not due to a difference in the leg lengths, we need to identify where that difference is coming from and treat accordingly. This could involve stretching, join range of movement exercises, strengthening weak muscles, prescription of orthotics (shoe inserts) and evaluation and changing of footwear.
If you suspect you may have a difference in the length of your legs, or are experiencing the symptoms listed above, do not hesitate to give our office a call and chat through your concerns with a podiatrist – (02) 9231 0518.