Abstract
Introduction Plantar foot pressure measurements using pressure distribution instruments is a standard tool for diagnostic and therapeutic interventions. Foot pressure studies have measured pressure distributions in patients with various conditions such as rheumatoid arthritis, diabetes and obesity . Pressure studies in metatarsalgia and Hallux rigidus, to our knowledge, has not been reported previously. Our aim was to measure plantar foot pressures in normal individuals and to compare them with variations in patients with metatarsalgia and Hallux rigidus. This data may enable us to identify areas of abnormal pressure distributions and thus plan foot-orthosis or surgical intervention.
Materials and Methods This was a case control study. We measured the plantar foot pressures in different parts of the foot in normal subjects of various ages and then compared this with foot pressures of patients with metatarsalgia and hallux rigidus. For measurement and statistical analysis, the plantar contact of the foot was divided into six anatomical divisions. The foot pressures were measured under the hallux, head of first metatarsal, over heads of second, third and fourth metatarsals, the fifth metatarsal, midfoot and hindfoot. This was measured using the FSCAN insole pedobarograph system (Tekscan, Inc, Boston, MA).
Results The foot pressures were measured in Kilopascals(Kpa). Independent T-tests was used to compare mean pressure distributions in the six anatomical divisions. Comparing normal with metatarsalgia, the mean pressures through the 5th metatarsal head 217(t=−2.32,p< 0.05) and midfoot 94(t=−3.17, p< 0.05), were significantly higher when compared to pressures in normal subjects. In patients with hallux rigidus, the mean pressures through the hallux 314 (t=−3.62, p< 0.01) and mid-foot 140 (t=-5.11, p< 0.01), were significantly higher, as compared to pressures in normal subjects.
Discussion Metatarsalgia is a condition that presents with pain under the region of the 2nd to 4th metatarsal heads. Hence, the normal response of the body would be to avoid putting increased pressure through this region, thus causing increased pressures to be transmitted through other parts of the foot. The foot pressures through the hallux and midfoot were higher in patients with hallux rigidus (compared to normal). This results in pressure imbalances and thus may contribute to pain, deformity and abnormal gait. Our study, confirms this, the mean plantar foot pressures were higher under the 5th metatarsal head and the midsole as compared to normal subjects. This could be explained by the tendency to walk on the outer aspect of the sole to avoid the painful area. Thus, any foot orthosis or surgery should aim to redistribute these forces.
Conclusion We have demonstrated increased pressures transmitted through the outer aspect of the sole of the foot, in patients suffering from metatarsalgia. The pressures through the Hallux and midfoot were higher in oatients with hallux rigidus. This information can be used further to plan any foot-orthosis or surgery to distribute pressures more evenly across the sole of the foot.
Correspondence should be addressed to Mr Carlos Wigderowitz, Honorary Secretary BORS, University Dept of Orthopaedic & Trauma Surgery, Ninewells Hospital & Medical School, Dundee DD1 9SY.
None of the authors have received anything of value from a commercial or other party related directly or indirectly to the subject of the presentation
