Quantitative determination of intermetatarsal pressure

Pain, plantar to the metatarsophalangeal joints, is a common location for the presentation of pain in the forefoot. In the absence of fractures or specific inflammatory conditions common causes of pain in this area include: (1) nonspecific metatarsalgia, (2) plantar fat pad atrophy, and (3) interdigital (intermetatarsal) neuroma. The aggravation and possibly the etiology of these forms of forefoot pain may be related to acute or chronic extrinsic pressure to the forefoot. The role of nonweightbearing, compression of the metatarsal heads, weightbearing, and toe-stance (on the metatarsal heads) on the intermetatarsal pressure of the third interspace was measured in eleven asymptomatic volunteers. Intermetatarsal pressures were recorded using the Stryker Miniaturized Digital Fluid Pressure Monitor. Intermetatarsal pressures for nonweightbearing, nonweightbearing with medial-lateral compression of the metatarsal heads, weightbearing, and toe stance averaged 21 mm Hg, 22 mm Hg, 29 mm Hg, and 36 mm Hg, respectively. In comparison to nonweightbearing, significant increases in intermetatarsal pressures were measured with weightbearing (P = .0027) and toe stance (P = .0002). The change noted from weightbearing to toe-stance was also significant (P = .0005). These findings support the proposition that increases in forefoot plantar pressures convey greater pressures to the intermetatarsal space and metatarsal heads. Increased pressures to the intermetatarsal space may likewise lead to or exacerbate the symptoms of patients with fat pad atrophy, nonspecific metatarsalgia and Morton's neuroma.