Identifying Signs of Limb Length Differences with F-Scan
Case Study

Identify Signs of Limb Length Discrepancy with F-Scan

This case study demonstrates how the F-Scan enables you to identify several factors that may indicate limb length differences (LLD) and helps determine the proper orthotic modifications.

Using Plantar Pressure Analysis to Detect Limb Length Discrepancy

by Bruce E. Williams, DPM
Merrillville, IN

Dr. Bruce Williams shows examples of using the F-Scan™ in-shoe analysis system to identify limb length discrepancy.

Normal Pressure ProfileNormal Pressure Profile

Normal Patterns

1) Notice the higher pressure under the 1st metatarsal head on the right foot. This could be an indication of a short side limb.

2) The Center of Force (CoF) icon on the right has accelerated faster than the CoF icon on the left.

3) Notice the early loss of heel pressure on the shortside limb.

Limb Length Difference Left SideLimb Length Difference Left Side

LLD Left Side Pressure Profile (Before)

Displayed at left is an example of a patient with a short limb on the left side. The patient has a 3/8" LLD left foot. Notice the early reduction of heel pressure left, and the faster acceleration for the CoF icon. There is also greater sub 1st mpj pressure on left. The above indicate the presence of left side LLD.

Limb Length After Heel LiftLimb Length After Heel Lift

Pressure Profile After Heel Lift Added

Displayed at left is the same patient after addition of a 3/8" korex heel lift on the left orthotic. Notice that left vs. right heel pressures are much more symmetrical, as is the pressure under the 1st metatarsals. The CoF icons are also at the same level, indicating equalization in the acceleration.