Understanding Leg Length Discrepancy

For efficient movement of the human body there must be a well-aligned musculoskeletal system. Most of us have fairly similar leg lengths – however, many do not, and their legs are noticeably uneven. Many of the symptoms of leg length discrepancy (LLD) are treatable if the cause and type of LLD is identified early on.

Leg length discrepancy is a common among both children and adults, with statistics showing that between 90-95.5% of the population is affected. A survey conducted at the Children’s Hospital in Boston showed that 93% had a leg length discrepancy. Leg length discrepancy can have a great effect on the spine and hips, as well as the foot. A difference of more than 1cm is where the discrepancy starts to affect normal body alignment, but in a person with a largely sedentary lifestyle, this will usually have little to no effect on them. The effects may start to show when the person increases their level of activity.

Symptoms of leg length discrepancy include:

  • Lower back pain
  • Hip pain
  • A single flat foot and/or raised arch
  • A tendency for body weight to always be shifted to the longer side
  • A tilted pelvis
  • Achilles tendonitis
  • An early heel lift
  • Bow legs or knock knees
Leg length discrepancy may not be visible to the naked eye, and require a podiatrist to take measurements. | Family Podiatry Centre | Best Foot Doctor Podiatrist DPM Clinic Singapore Malaysia

What causes Leg Length Discrepancy?

There are 2 types of leg length discrepancy: Structural and Functional, which are caused by different factors.

  1. Structural leg length discrepancy, the actual difference in length of femur/tibia.
    • This may be caused be genetics, a surgery (e.g knee replacement) or prior trauma (e.g a fracture).
  2. Functional leg length discrepancy, when bone components are equal in length but function asymmetrically.
    • This may be from hip flexion contractures, prior trauma, excessive pronation/supination, a pelvic anomaly (e.g scoliosis), hyperextension of knees/ankles or misalignment of the knee.

Sometimes it is difficult to differentiate which type of leg length discrepancy a patient is suffering from as it is not unusual to have both arise together. Symptoms are also usually worse on the longer side, due to increased stance time and over-pronation on the limb. The human body will also try to compensate for the disparity, which can take a few forms:

  • Subtalar joint: pronation (flattened arch) of the longer leg and supination (raised arch) of the shorter leg 
  • Ankle joint: plantarflexion (pointing towards the ground) of the shorter leg 
  • Knee joint: hyperextension of the long leg or over-flexion of the knee on the long side
  • Uneven arm swing or shoulder tilt

Best Leg Length Discrepancy Treatment

To check for leg length discrepancy, podiatrists will conduct a thorough physical examination and use specific tests to confirm or diagnose a discrepancy in length. 

This involves taking tape measurements from the anterior superior iliac spine (the front of the hip) to the medial malleolus (inner ankle) several times, then taking an average length. The presence of a leg length discrepancy can be observed during a podiatrist’s gait analysis in-clinic as well, and these can include signs of shoulder tilt, unequal arm swing, pelvic tilt, excessive knee flexion or excessive high/low arch of the foot on one side. X-rays are also useful in determining leg length structurally, information on the bone quality of the limbs and any anatomical anomalies. 

Leg length discrepancy can be treated both surgically and non-surgically. 

Non-surgical methods 

  • Heel lifts using customised orthotics, tailored specifically to compensate for the exact discrepancy in leg length
  • Shoe modifications 
  • Stretching the contracted muscle groups to try and pull them to the same length

Surgical procedures can also be done to correct leg length discrepancy permanently.

Everyone’s case of leg length discrepancy is different. If yours is giving you problems, do not hesitate to book a consultation with a podiatrist to find out more about your leg length discrepancy.

Written by Mark B. Reyneker
Written by Mark B. Reyneker

Based in Singapore, 20 years of clinical experience. Practiced in South Africa, Malaysia, and Singapore. Pioneered CAD/CAM custom-made orthotics in S.E Asia.

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