Prevalence of Altered Foot Posture in Osteoarthritis of Knee

Abstract

Osteoarthritis (OA) is a non-inflammatory progressive degenerative disorder of weight bearing joint. Changes in foot posture may cause increased mechanical rotational stress on the knee joint and may alter alignment and dynamic function of lower limb. To understand the effect of foot orthosis and footwear modification as a non-operative treatment and to identify patients who are most likely to benefit from it, greater knowledge of foot structure in this population is required to find altered foot posture in medial and lateral compartment OA knee using Navicular Drop Test (NDT) and Arch Index (AI). A cross sectional study done on 100 Osteoarthritis patients diagnosed with ACR clinically diagnostic criteria. Patients were evaluated using NDT and AI. NDT: Using a rigid ruler the height of navicular tuberosity in neutral talus position and relaxed standing position was measured. AI: A foot print was taken on graph paper and divided into 3 equal parts A (anterior), B(middle), C(posterior). The results showed that 64% had medial compartmental OA knee and 36% had lateral compartmental OA knee. Out of total population patient showed equal amount of pronation and supination i.e. 36%, while 28% having no alteration in foot posture. Medial compartment had 19.20% pronated foot due to knee adduction moment arm. 28.12% had supinated foot in order to decrease load on lateral compartment and to delay further degenerative process. The study concluded that medial compartment OA and lateral compartment OA showed more pronated and supinated foot type respectively.

Foot Posture Characteristics in Medial Knee Osteoarthritis Patients

“…Pronated feet were the most frequent among the abnormal foot. 9,10,12 This situation might be a consequence for medial KOA or as risk factor, to date it still cannot be determined yet. Patient with medial KOA tend to have a more varum alignment of the knee.…”

“…9 Pronated foot more frequent in medial KOA might due to biomechanical changes that occurs during abnormal loading of knee joint during weight bearing activities. 9,10 In order to decrease KAM, foot adapts subtalar joint in to pronated position. 10 Thus, shift the knee load more laterally and further decrease load on medial compartment.…”

“…9,10 In order to decrease KAM, foot adapts subtalar joint in to pronated position. 10 Thus, shift the knee load more laterally and further decrease load on medial compartment. However, there were some individual in medial KOA with supinated foot.…”

“…9 Specific foot posture might cause greater mechanical stress over knee joint. 10 Meanwhile, KOA may also affect foot motion during walking, 10 hence foot posture might play significant role in KOA setting. There are several type of foot postures.…”

“…12 In Surlakar and colleagues's research , they reported that there were 36% participants with pronated foot, 36% subjects with supinated foot and the rest with normal foot and among medial KOA subjects, there were 83.30% subjects have pronated foot. 10 As foot posture can directly influence the distribution of knee loading in medial KOA patients, 10 a conservative strategy using orthoses and footwears were developed to decrease the medial loading of knee joint. There are various kinds of foot orthoses that have been applied to decrease knee pain and improve functional capacity of the patients suffering from KOA.…”