The Influence of Percentage Weight-Bearing on Foot Radiographs

Area of Science:

• Orthopedics
• Radiology
• Biomechanics

Background:

• Clinical decisions in foot conditions often rely on weight-bearing radiographs.
• The impact of varying weight-bearing levels on specific foot radiographic measurements is not fully understood.

Purpose of the Study:

• To investigate how different percentages of body weight affect standard radiographic measurements of the healthy foot.

Main Methods:

• A prospective study involving 20 healthy individuals.
• Radiographs of the foot were taken under five conditions: non-weight-bearing, 10%, 25%, 50%, and 100% body weight.
• Key measurements included hallux valgus angle (HVA), 1-2 intermetatarsal angle (IMA), talonavicular coverage angle (TNCA), talocalcaneal angle (TCA), forefoot width, LisFranc distance, cuboid height to ground (CHG), and talo-first metatarsal angle (TMA).

Main Results:

• Increased weight-bearing significantly elevated the talonavicular coverage angle (TNCA) and talocalcaneal angle (TCA).
• Cuboid height to ground (CHG) significantly decreased with higher weight-bearing percentages.
• Hallux valgus angle (HVA), 1-2 intermetatarsal angle (IMA), forefoot width, LisFranc distance, and talo-first metatarsal angle (TMA) showed no significant changes across weight-bearing conditions.

Conclusions:

• Increasing body weight on the foot leads to a flatter medial arch, increased hindfoot valgus, and midfoot rotation/abduction, as evidenced by changes in TNCA, TCA, and CHG.
• Radiographic measurements of the foot remain stable between 25% and 100% body weight.
• Graduated weight-bearing protocols post-injury or surgery may only be clinically relevant if the patient's weight-bearing level is below 25% or above this threshold.