True Leg Length Test

Orthopedic Exam / Special Tests for Physical Therapy: KNEE/ HIP

True Leg (True Tibia & Femur) Length Test:

Leg Length Discrepancy:

There are two classifications of leg length discrepancy, Functional, sometimes referred to as ‘apparent ‘ and Anatomical, sometimes referred to as a ‘true’.

Anatomical or true leg-length discrepancies are when there are actual skeletal differences in the shape and length of the leg bones, such as the femur, tibia and fibula. They can also include deformities of the foot and ankle bones as well as the pelvis. These bony differences are further subdivided into two categories; those that shorten a limb and those that lengthen it. Congenital growth deficiencies, bone or joint infections, growth plate fractures or dysfunctions, among other things can cause lower limb shortening.

Functional or apparent leg length discrepancies are classed as those where there are no bony differences and the legs are technically the same length, instead its other conditions such as spinal scoliosis, pelvic asymmetries create the appearance of one leg being longer or shorter than the other. Other possible causes are so called ‘excessive’ ankle pronation, knee genu varum or valgum, or even possibly due to soft tissue contractures or imbalances.

True Leg (True Tibia & Femur) Length Test:


  • Testing for the tibia and femur lengths

Video Demo Instructions, Procedure, Positive Test:

True Leg (True Tibia & Femur) Length Test: SUPINE

True Tibia & Femur Length Test: Procedure: PRONE

• Patient is prone
• Patient’s knees and hips flexed , with the plantar surfaces of their feet on the table.
• Their medial malleoli even and knees together

To compare the lengths:

• Tibia: Therapist stands at the foot of the table to compare the heights of the patient’s tibial plateaus to look for the shorter tibia
• Femur: Then therapist stands at the side of the table to compare the positions of the patellas looking for the shorter femur.