User Tools

Site Tools


introduction

Introduction

Objectives

Most radiologists are familiar with the basic measurements used to evaluate alignment of the adult foot on skeletal radiographs. However, not all of us have a clear understanding of the basis for these measurements ie. the anatomic changes occurring in the foot that produce these abnormalities. An understanding of the biomechanical basis for these radiographic abnormalities of alignment is key. Although the orthopedist places a great deal of importance on the clinical and physical examination, the radiograph is an essential part of the assessment.

In this tutorial we will:

  1. Present the abnormalities of foot alignment most commonly seen by the orthopedist and examine the biomechanical basis for malalignment.
  2. Discuss the normal and abnormal radiographic lines, angles, and measurements utilized in evaluating common alignment abnormalities.
  3. Review some of the treatment options commonly employed to correct the deformity

Importance of Weight-bearing Radiographs in Evaluation of the Foot

Both PA (dorsoplantar) and lateral views of the foot are required to assess alignment. The importance of obtaining FULL weight-bearing views cannot be overly emphasized. The non-weight bearing position may mask significant abnormalities that only manifest in the position of function, and measurements will therefore be totally invalid. Just as the clinical examination is based on evaluation of the foot in a position as close to functional as possible, so should also the radiographic examination. Full weight-bearing AP and lateral views in the natural base and angle of stance, have been shown to closely approximate the position of dynamic gait (1).

The following are lateral views of the same patient with different degrees of weight bearing. The true extent of the alignment abnormality is revealed only on the FULL weight-bearing view.

Non weight-bearing: Normal alignment

Non weight-bearing: normal alignment

Simulated weight-bearing: Mild pes planus (flatfoot)

Simulated weight-bearing: mild pes planus (flatfoot)

Full weight-bearing: severe pes planus

Full weight-bearing: severe pes planus

Often when patients have a painful extremity almost 70-80% of their body weight is placed on the less painful side. Therefore, full weight should be placed only on the affected leg. One radiographic clue that a lateral view is not fully weight-bearing is that the tibia is less than vertical.

Full weight-bearing. The tibia is perpendicular to the floor.

Full weight-bearing. The tibia is perpendicular to the floor.

Partial weight-bearing. Note that the tibia is angled relative to the floor.

Partial weight-bearing. Note that the tibia is angled relative to the floor.

Partial weight-bearing. Note that the tibia is angled relative to the floor.

Partial weight-bearing. Note that the tibia is angled relative to the floor.

Onward to pes planus!!

introduction.txt · Last modified: 2016/08/14 01:33 (external edit)