The Nijmegen classification of forefoot disorders in rheumatoid arthritis was first proposed in 2011 by researchers from the Radboud University Medical Center in Nijmegen, the Netherlands to grade the severity of the forefoot deformity.
The classification is based on the sequence of the functional and anatomical changes that typically occur in the foot with rheumatoid arthritis. It has four different grades from 0 to 3, with grades 2 and 3 having an additional classification of (a) or (b) depending on the absence or presence of hallux valgus.
Nijmegen Classification of Forefoot Disorders:
Grade 0: No clinical and no or very minimal radiographic changes in the MTP joints; no clinical changes in motion and no deformity.
Grade 1: Clinical and/or radiographic changes in one or more of the MTP joints, however, the mobility of the joints have not decreased the ability to plantarflex the joints sufficiently to put the plantar soft tissues back in place. The clinical symptoms are most probably related to the loss of cushion support from the plantar fat pad.
Grade 2: Loss of plantar flexion in one or more of the MTP joints; the loss of plantar flexion is such that the plantar soft tissues can no longer be reducible under the plantar aspect of one or more of the metatarsal heads.
a. With a hallux valgus greater than 20°
b. With a hallux valgus 20° or less
Grade 3: Extension contracture in one or more MTP joints, with or without radiographic subluxation or dislocation; due to the dorsally extended position of the MTP joint, the plantar fat pad is stretched distally around the metatarsal head.
a. With a hallux valgus greater than 20°
b. With a hallux valgus of 20° or less
Key Reference:
Peter F. Doorna, Noe¨l L .W. Keijsers, Jacques van Limbeek, Patricia G. Anderson, Roland F.J.M. Laan, Paul van’t Pad Bosch, Maarten C. de Waal Malefijt, Jan Willem K. Louwerens: A clinical classification system for rheumatoid forefoot deformity. Foot and Ankle Surgery 17 (2011) 158–165; 2011 (link)
In this study, the authors classified the forefoot of 94 people with rhuematoid arthritis using the Nijmegen classification. They also collected the VAS for pain with respect to the pain on the plantar aspect of the forefoot, the Foot Function Index and plantar pressure measurements. The authors concluded:
Despite the large variation between subjects in a certain grade, a clear trend was found between increase in grades of the introduced classification of forefoot disorders in patients with rheumatoid arthritis and VAS for pain, FFI difficulty with activities, and plantar peak pressure under the metatarsals. Therefore, the findings in the present study substantiate the usability of this proposed system to grade rheumatoid forefoot deformity based on the sequence of anatomical changes. The Nijmegen classification of forefoot disorders in patients with rheumatoid arthritis can be used to clearly define patient groups and foot deformities in order to perform future prospective comparative studies.
Other research using the Nijmegen Classification of Forefoot Disorders:
Andres Reinoso-Cobo et al; Morpho-structural characteristics of feet in patients
with rheumatoid arthritis: A cross sectional study. Int. J. Med. Sci. 2021, Vol. 18 (link)
Joost C.Schrier et al; Resection or preservation of the metatarsal heads in rheumatoid forefoot surgery? A randomised clinical trial. Foot and Ankle Surgery Volume 25, Issue 1, February 2019, Pages 37-46 (link)
Niki M.Stolwijk et al; Treatment of metatarsalgia based on claw toe deformity through soft tissue release of the metatarsophalangeal joint and resection of the proximal interphalangeal joint: Evaluation based on foot kinematics and plantar pressure distribution. Foot and Ankle Surgery Volume 26, Issue 7, October 2020, Pages 755-762 (link)
Books on rheumatology and the foot:
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