Proximal and distal contributions to lower extremity injury: A review of the literature

Abstract

Excessive or prolonged foot pronation has been linked to the development of numerous overuse injuries affecting the lower limb. The originally proposed pathomechanical model suggests foot motion affects more proximal structures through disruption of distal to proximal coupling between the foot, tibia, femur, and hip. Research evidence supports the presence of a dynamic coupling mechanism between lower limb segments, however, the direction of the coupling is inconclusive.

Recent prospective investigations of the role of the lumbo-pelvic hip complex have identified a strong association between proximal dysfunction and increased risk of lower limb injuries. Strength of muscles of the lumbo-pelvic hip complex (core muscles) is suggested to be essential to controlling hip abduction, subsequent internal rotation of the femur and potentially more distal movement. Proximal muscle weakness and altered motor control have also been implicated in the development of numerous lower limb injuries, many of which have previously been attributed to excessive foot pronation.

This review discusses the theoretical basis for the role of proximal and distal structures in biomechanical dysfunction of the lower limb and the development of lower limb overuse injury. Current prospective evidence relating to the contributions of excessive foot pronation and core muscle function to the development of lower extremity injury is evaluated.

Introduction

Generalised excessive or prolonged foot pronation has been implicated in numerous functional changes to the lower limb resulting in overuse injuries affecting the lower back, hip, knee, lower leg, ankle, and foot [1], [2]. The proposed mechanism of injury is via the propagation of abnormal functional mechanics proximally [3]. Closed chain pronation occurring at the subtalar joint (STJ) involves eversion of the calcaneus and adduction and plantarflexion of the talus [4]. The position of the talus within the ankle mortise creates a coupling mechanism, transferring pronation of the foot into rotation of the tibia via articulations at the ankle subtalar and midtarsal joints [5]. This in turn, is temporally linked to hip movement with rearfoot pronation coupled with internal rotation of the femur, and rearfoot supination synchronous with external rotation at the hip [6], [7], [8]. Disruption of the coupling mechanism has been implicated in the development of numerous musculoskeletal injuries of the lower limb [7], [9], [10]. Excessive or prolonged pronation is proposed to delay external rotation of the tibia and disrupt timing between knee extension and rearfoot supination [11], [12], [13]. This pathomechanical model has been associated with development of patellofemoral syndrome [13], [14], altered position and function of the hip and pelvis [15], [16], and the development of lower back pain [17], [18].

More recently, attention has turned to the role of proximal structures in biomechanical function of the lower limb and the development of lower extremity injury [19], [20], [21]. There is a growing body of evidence identifying strength of muscles of the lumbo-pelvic hip complex (core muscles) as being essential to controlling hip abduction, subsequent internal rotation of the femur, and potentially more distal movement [19], [22], [23], [24]. In addition, dysfunction of core muscles has been implicated in the development of various lower limb injuries, many of which have also been attributed to excessive foot pronation [19], [22], [25]. As a result, the potential for lumbopelvic instability to drive lower limb pathomechanics is increasingly being investigated.

The purpose of this review is to investigate prospective studies relating to the roles of foot pronation and core stability in biomechanical function and injury of the lower limb.