October 16, 2003

Sports Medicine Conference

Foot and Ankle Biomechanics

v    Gait and alignment

v    Ankle joint

v    Subtalar joint

v    Syndesmosis injury

v    Midfoot

v    forefoot

Clinical Diagnosis

v    Gait cycle

v    stance phase ( shock dissipation and force generation)

v  heel strike

v  lateral column loading

v  foot flat

v  load transmission across midfoot               ( pronation ) to medial column

v  push off  (force generation)

Clinical Diagnosis

v    Gait cycle

Terminology of motion can be confusing

v    Varus/Valgus and Abd/Add should have one clear axis for measuring angles

v    Pronation/Supination describe motion about more than one axis leading to confusion

Pronation

v    Dorsiflexion of the ankle

v    Eversion of calcaneus (subtalar joint)

v    Abduction of forefoot

Supination

v    Plantar flexion of the ankle

v    Inversion of the calcaneus      (subtalar joint)

v    Adduction of the forefoot

Clinical Diagnosis

Physical Exam

v    Gait cycle

v    examination

v  biomechanical

Clinical Situations

Physical Exam

v    examination

v  biomechanical

v  neurologic

v  vascular

Basic Principles:       Gait cycle

Moment Arm

v    Action of muscle/tendon highly depends the position of its line of action in relation to the joint axis (i.e. moment arm)

v    Muscle mass also matters

v    Absolute torque determined by moment arm and force (muscle mass)

Plantar aponeurosis via dorsiflexion of the MP joint also contributes to heel inversion

v     PA Extends from heel to plantar plate (base of PP)

v     This mechanism starts with heel rise

Eversion aligns TT joints
Inversion removes parallel alignment

Joints critical to motion
of foot during gait

Metatarsal Break

v     Location of MP joints creates obliquity in relation to axis of foot

v     Metatarsal break encourages hindfoot and midfoot inversion with heel rise in concert with ST and TT joints

Clinical Diagnosis

Physical Exam

Acute Ankle Instability

Acute Ankle Instability

v    Acute Ankle Arthroscopy:

v    van Djik (1994)

v    66% medial talar chondral lesion

OLT: Diagnosis

v    Diagnosis commonly missed,     delayed

v    Chronic pain, swelling,

v          giving way

v    ± associated instability

Chronic Ankle Instability

v    Ankle Instability

v    Functional

v    Mechanical

v    Subtalar

Chronic Ankle Instability

Chronic Ankle Instability

v    Functional

v    Mechanical

-      Failure of static components

-      Failure of dynamic mechanisms to compensate 

v    Subtalar

Chronic Ankle Instability

v    Stress Radiography: 

v    Is it Useful?

v    Talar tilt

v    Anterior drawer

Chronic Ankle Instability

v    Stress X-rays for Acute Sprains (7 papers):

v     ( Frost, Amendola, CJSM, 1999 )

v    6 of 7 authors concluded that AD or TT stress x-rays inadequate in assessing degree of instability

Chronic Ankle Instability

v    Surgical Options:

v    Anatomic     - Brostrum (and modifications)

v    Non-anatomic  - Evans

              - Watson-Jones

              - Chrisman-Snook

              - others

Chronic Ankle Instability

v    Authors Approach:

v    Anatomic            - Brostrum repair

      - direct repair to bone

      - Gould (extensor retinaculum)

Chronic Ankle Pain

Etiology:

v    Soft tissue lesions

v    Anterolateral impingement

v    Syndesmosis injury

v    Peroneal tendinitis/subluxation

v    Sinus tarsi/ subtalar joint injury

v    Peroneal nerve injury

Ankle Syndesmosis: Anatomy

Ankle Syndesmosis: Function

v    Stability

v    Weight transmission

v     Accommodate talar motion

Syndesmosis Injury: Treatment

v    External rotation

v    Acute dorsiflexion

v    Severe ankle sprain

Syndesmosis Injuries 

Physical Exam

v    Tenderness

v    External rotation stress     test

v    Squeeze test

v    Stability test

Chronic Syndesmosis  Injuries

X-rays

v    Diastasis

v    Calcification

v    Posterior tibial avulsion

Syndesmosis Sprains

Syndesmosis Sprains: stress testing

 Midfoot Sprains : Diagnosis

v    True Lisfranc fracture dislocations are not difficult to diagnose, but...

·      clinical exam

·      X-ray findings

   Introduction

v    Tarsometatarsal joints (Lisfranc) Injuries

·    Anatomy

·    Biomechanics

·    Injury Classification

·    Subtle Injuries or Sprains ( BEWARE)

·    Lisfranc fracture dislocation

 Midfoot Sprains : Anatomy

 Midfoot Sprains : Anatomy

Midfoot Sprains : Biomechanics

v    “Non- essential” joint

v    stability, shock dissipation not mobility

v    maintain longitudinal and transverse arches

v    medial column Ù stability

Clinical Situations

A. Forefoot

             1. Hallux Rigidus, Turf Toe, Sesamoiditis

Clinical Situations

A. Forefoot

Clinical Situations

A. Forefoot