Background/Purpose:

Foot pain is a risk factor for disability; however, not all foot pain is the same. Foot pain etiology can vary by region (e.g., toe pain may arise from overlapping toes, forefoot pain from hallux valgus), suggesting its effects on foot biomechanics may differ as well. Therefore, the aim of this study was to evaluate differences in foot biomechanics during gait by region of foot pain.

Methods:

Framingham Foot Study participants with complete data on regional foot pain, foot biomechanics, and foot disorders were included in this study.

A trained examiner conducted a validated foot exam to determine presence of the following structural foot disorders: hallux valgus, hallux rigidus, claw toes, overlapping toes and hammer toes. 

Biomechanical data were collected using a pressure mat (Tekscan Matscan) as participants walked barefoot at a self-selected pace. Data were processed (Novel Automask) to extract maximum force and peak pressure at the toes, forefoot, midfoot, and rearfoot.

Participants selected location(s) of foot pain from a graphic, with location options including toe, nail, ball of foot, forefoot, arch, heel and hindfoot. The eight locations of pain were collapsed into four regions: toes (toe and nail pain); forefoot (forefoot and ball pain); midfoot (arch pain); and rearfoot (heel and hindfoot pain).

Each foot was classified into one of seven groups: 1) toe pain only; 2) forefoot pain only; 3) midfoot pain only; 4) rearfoot pain only; 5) pain in two regions; 6) pain in three or more regions; and 7) no regional pain (referent).

A per-foot analysis using General Estimating Equations (SAS, v. 9.3) determined associations between regional foot pain and biomechanical measures, adjusting for age, gender, weight and presence of structural foot disorders. Alpha was set to p≤0.05.

Results:

There were 3158 participants (6280 feet) included (age: 66 ± 10.5 years; BMI: 28 ± 5.5 kg/m²; 56% women), with 2634 (42%) feet having one or more structural foot disorder.

After adjustment, individuals with midfoot pain had higher midfoot force with greater toe pressure (Figure 1), while those with forefoot pain had greater rearfoot force and less toe force, compared to the referent. Individuals with pain in toes, rearfoot, and multiple regions typically displayed lower rearfoot pressure and force relative to the referent.

Conclusion:                                                          

Region of foot pain is associated with biomechanical differences at the pain locale and other foot regions. These results suggest that region of foot pain may be associated with biomechanical differences during gait at other lower extremity joints (e.g., knee and ankle). As changes in gait affect mobility and fall risk, future work should evaluate how region of foot pain affects lower extremity function, falls and disability.