Foot and Ankle

Question 1

Foot Muscle Forces & Deformities

1. Equinovarus foot = most common deformity following _____
   a. Use _____ and ________ for at least 6 months to await for possible neuro recovery
   b. overactivity of the _?_ (1 main; 3 minor)
2. Treatment : nonoperative [3]
3. Treatment : Surgical [3]
4. Silverskolds test

Answer 1

1. Equinovarus foot = most common deformity following stroke
   a. use AFO and physical therapy for at least 6 months to await for possible neuro recovery
   b. overactivity of the tibialis anterior, with contributions from the FHL, FDL, and PTT
2. Treatment : nonoperative

• AFO fitting
• physical therapy
• Phenol or botox injections

3. Treatment: surgical

• split anterior tibial tendon transfer (SPLATT)
• flexor hallucis longus tendon transfer to the dorsum of the foot and release of the flexor digitorum longus and brevis tendons at the base of each toe
• gastrocnemius or achilles lengthening

4. Silfverskiöld test

• improved ankle dorsiflexion with knee flexed = gastrocnemius tightness
• equivalent ankle dorsiflexion with knee flexion and extension= achilles tightness

Question 2

Gait Cycle

1. Gait cycle definition
2. Gait cycle phases?
3. Define Stride
4. Define Step

Answer 2

1. One gait cycle is measured from heel-strike to heel-strike
2. Consists of:

• stance phase:
  
  • period of time that the foot is on the ground
  • ~60% of one gait cycle is spent in stance
  • during stance, the leg accepts body weight and provides single limb support
• swing phase
  
  • period of time that the foot is off the ground moving forward
  • ~40% of one gait cycle is spent in swing
  • the limb advances

3. Stride = distance btwn consecutive inital contacts of same foot with the ground

4. Step = is the distance between initial contacts of the alternating feet

Question 3

Stance Phase

1. Initial contact (heel strike)
2. Loading response (initial double limb support) - marks beginning of initial double limb stance
3. Mid-stance (single limb support)
4. Terminal stance (single limb support)definition
5. Pre-swing (second double limb support)

Answer 3

• Initial contact (heel strike)
  
  • definition occurs when foot contacts the ground
  • muscular contractions
    
    • hip extensors contract to stabilize the hip
    • quadriceps contract eccentrically
    • tibialis anterior contracts eccentrically
• Loading response (initial double limb support): marks beginning of initial double limb stance
  
  • definition: occurs after initial contact until elevation of opposite limb; bodyweight is transferred on to the supporting limb
  • muscular contractions
    
    • ankle dorsiflexors (tibialis anterior) contract eccentrically to control plantar flexion moment
    • quads contract to stabilize knee and counteract the flexion moment (about the knee)
• Mid-stance (single limb support): initial period of single leg support
  
  • definition: from elevation of opposite limb until both ankles are aligned in coronal plane
  • muscular contractions
    
    • hip extensors and quads undergo concentric contraction
• Terminal stance (single limb support)
  
  • definition: begins when the supporting heel rises from the ground and continues until the opposite heel touches the ground
  • muscular contractions
    
    • toe flexors and tibialis posterior contract and are the most active during this phase
• Pre-swing (second double limb support): is the start of the second double limb stance in the gait cycle
  
  • definition : from initial contact of opposite limb to just prior to elevation of ipsilateral limb
  • muscular contractions
    
    • hip flexors contract to propel advancing limb

Question 4

Swing Phase

1. Initial swing (toe off)
2. Mid-swing (foot clearance)
3. Terminal swing (tibia vertical)

Answer 4

Initial swing (toe off) : start of single limb support for opposite limb

• definition
  
  • from elevation of limb to point of maximal knee flexion
• muscular contractions:
  
  • hip flexors concentrically contract to advance the swinging leg

Mid-swing (foot clearance)

• definition
  
  • following knee flexion to point where tibia is vertical
• muscular contractions
  
  • ankle dorsiflexors contract to ensure foot clearance

Terminal swing (tibia vertical)

• definition
  
  • from point where tibia is vertical to just prior to initial contact
• muscular contractions
  
  • hamstring muscles decelerate forward motion of thigh

Question 5

Variables Affected During Gait Cycle

1. Pelvic rotation
2. Pelvic tilt
3. Knee flexion in stance
4. Foot mechanisms
5. Knee mechanisms
6. Lateral displacement of pelvis
7. Center of gravity (COG)

Answer 5

1. Pelvic rotation

• Pelvis rotates 4 degrees medially (anteriorly) on swing side
  
  • lengthens the limb as it prepares to accept weight

2. Pelvic tilt

• pelvis drops 4 degrees on swing side
  
  • lowers COG at midstance

3. Knee flexion in stance

• early knee flexion (15 degrees) at heel strike
  
  • lowers COG, decreasing energy expenditure
  • also absorbs shock of heel strike

4. Foot mechanisms

• ankle plantar flexion at heel strike and first part of stance

5. Knee mechanisms

• at midstance, the knee extends as the ankle plantar flexes and foot supinates
• restores leg to original length
• reduces fall of pelvis at opposite heel strike

6. Lateral displacement of pelvis

• pelvis shifts over stance limb
  
  • COG must lie over base of support (stance limb)

7. Center of gravity (COG)

• in standing position is 5cm anterior to S2 vertebral body
• vertical displacement
  
  • during gait cycle COG displaces vertically in a rhythmic pattern
    
    • the highest point is during midstance phase
    • lowest point occurs at the time of double limb support
• horizontal displacement
  
  • COG displaces 5cm horizontally during adult male step

Question 6

High Ankle Sprain & Syndesmosis Injury

1. Incidence: _._% of all ankle sprains without fracture; __% of all ankle fractures
2. MOI:
3. Pathoanatomy
4. Associated injuries [5]
5. Prognosis

Answer 6

1. 0.5% of all ankle sprains without fracture / 13% of all ankle fractures

2. MOI: most commonly assoc with ER injuries

3. Pathoanatomy: ER forces the talus to rotate laterally and push the fibula away from tibia which may lead to:

• increased compressive stresses seen by the tibia
• increased likelihood of lateral subluxation of the distal fibula
• incongruence of the ankle joint articulation

4. Associated injuries

• osteochondral defects (15% to 25%)
• peroneal tendon injuries (up to 25%)
• fractures: ankle / 5th MT base / ant process calc / lat OR post process of talus
• deltoid ligament injury
• loose bodies

5. Prognosis

• missed injuries may result in end-stage ankle arthritis
• excellent functional outcomes if syndesmosis is anatomically reduced

Question 7

Syndesmosis Injury

Anatomy

1. Distal tibiofibular syndesmosis includes [5]
2. Syndesmosis Biomechanics

• function
• normal gait (motion)
• deltoid ligament

Answer 7

1. distal tibiofibular syndesmosis includes

• anterior-inferior tibiofibular ligaments (AITFL)
  
  • originates from anterolateral tubercle of tibia (Chaput’s)
  • inserts on anterior tubercle of fibula (Wagstaffe’s)
• posterior-inferior tibiofibular ligament (PITFL)
  
  • originates from posterior tubercle of tibia (Volkmann’s)
  • inserts on posterior part of lateral malleolus
  • strongest component of syndesmosis
• interosseous membrane
• interosseous ligament (IOL)
  
  • distal continuation of the interosseous membrane
  • main restraint to proximal migration of the talus
• inferior transverse ligament (ITL)

2. Syndesmosis Biomechanics

• function
  
  • maintains integrity between tibia and fibula
  • resists axial, rotational, and translational forces
• normal gait
  
  • syndesmosis widens 1mm during gait
• deltoid ligament
  
  • indirectly stabilizes the medial ankle mortise

Question 8

Sydnesmosis Injury

Imaging

• Radiographs
• CT
• MRI

Answer 8

FINDINGS

XRay

• decreased tibiofibular overlap
  
  • normal >6 mm on AP view
  • normal >1 mm on mortise view
• increased medial clear space
  
  • normal less than or equal to 4 mm
• increased tibiofibular clear space
  
  • normal <6 mm on both AP and mortise views

CT

• indications
  
  • clinical suspicion of syndesmotic injury with normal radiographs
  • useful post-operatively to assess reduction of syndesmosis after fixation
• sensitivity and specificity
  
  • more sensitive than radiographs for detecting minor degrees of syndesmotic injury

MRI

• indications
  
  • clinical suspicion of syndesmotic injury with normal radiographs
• sensitivity and specificity
  
  • highly sensitive and specific for detecting syndesmotic injury

Question 9

Syndesmosis injury

Treatment

Answer 9

Nonoperative

• non-weight-bearing CAM boot or cast for 2 to 3 weeks
  
  • indications
    
    • syndesmotic sprain without diastasis or ankle instability
  • technique
    
    • delayed weight-bearing until pain free
    • physical therapy program using a brace that limits external rotation
  • outcomes
    
    • typically display a notoriously prolonged and highly variable recovery period
    • recovery may extend to twice that of standard ankle sprain

Operative

• syndesmosis screw fixation
  
  • indications
    
    • syndesmotic sprain (without fracture) with instability on stress radiographs
    • syndesmotic sprain refractory to conservative treatment
    • syndesmotic injury with associated fracture that remains unstable after fixation of fracture
  • outcomes
    
    • excellent functional outcomes if syndesmosis is accurately reduced
    • requires removal
• syndesmosis fixation with suture button
  
  • indications
    
    • same as for screw fixation
  • technique
    
    • fiberwire suture with two buttons tensioned around the syndesmosis
    • may be performed in addition to a screw
  • outcomes
    
    • early results promising with some showing earlier return to activity when compared to screw fixation
    • does not require removal

Question 10

Metatarsal Fractures

1. Goals of treatment include:
2. Epidemiology
3. Mechanism
4. Associated conditions
5. Prognosis

Answer 10

• Goals of treatment include:
  
  • maintenance of transverse and longitudinal arch of forefoot
  • restore alignment to allow for normal force transmission across metatarsal heads
• Epidemiology
  
  • 5th MT most commonly fractured in adults
  • 1st MT most commonly fractured in children less than 4 years old
  • peak incidence between 2nd and 5th decade of life
  • 3rd metatarsal fractures rarely occur in isolation
    
    • 68% associated with fracture of 2nd or 4th metatarsal
• Mechanism
  
  • direct crush injury
    
    • may have significant associated soft tissue injury
  • indirect mechanism (most common)
    
    • occurs with forefoot fixed and hindfoot or leg rotating
• Associated conditions
  
  • Lisfranc injury
    
    • Lisfranc equivalent injuries seen with multiple proximal metatarsal fractures
  • stress fracture
    
    • consider metabolic evaluation for fragility fracture
    • look for associated foot deformity
    • seen at base of 2nd metatarsal in ballet dancers
    • may have history of amenorrhea
• Prognosis
  
  • majority of isolated metatarsal fractures heal with conservative management
  • malunion may lead to transfer metatarsalgia

Question 11

Metatarsal Fractures

Answer 11

• Nonoperative
  
  • indications
    
    • first metatarsal -> non-displaced fractures
    • second through fourth (central) metatarsals
      
      • isolated fractures
      • non-displaced or minimally displaced fractures
    • stress fractures
      
      • second metatarsal most common
      • look for metabolic bone disease
      • evaluate for cavovarus foot with recurrent stress fractures
• Operative
  
  • indications
    
    • open fractures
    • first metatarsal
      
      • any displacement
        
        • no intermetatarsal ligament support
        • 30-50% of weight bearing with gait
    • central metatarsals
      
      • sagittal plane deformity more than 10 degrees
      • >4mm translation
      • multiple fractures
  • techniques
    
    • antegrade or retrograde pinning
    • lag screws or mini fragment plates in length unstable fracture patterns
    • maintain proper length to minimize risk of transfer metatarsalgia
  • outcomes
    
    • limited information available in literature