Foot Muscle Forces & Deformities

Introduction

Simple Deformities
Deformity	Strong Muscle	Weak Muscle
equinus	gastrocnemius-soleus complex	dorsiflexors
cavus	plantar fascia, intrinsics	dorsiflexors
varus	posterior tibialis and anterior tibialis	peroneal brevis
supination	anterior tibialis	peroneus longus
flatfoot	peroneus brevis	posterior tibialis
Complex Deformities
equinovarus + supination	gastroc-soleus complex, posterior tibialis, anterior tibialis	peroneus brevis & longus
equinovalgus	gastroc-soleus complex, peroneals	posterior tibialis, anterior tibialis
calcaneovalgus	foot dorsiflexors/evertors (L4 and L5)	plantar flexors /inverters (S1 and S2)

Introduction

Equinovarus foot
- most common deformity following stroke
  - use AFO and physical therapy for at least 6 months to await for possible neuro recovery
  - overactivity of the tibialis anterior, with contributions from the FHL, FDL, and tibialis posterior
- treatment
  - nonoperative
    - AFO fitting
    - physical therapy
    - Phenol or botox injections
  - 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

Physical Exam

Silfverskiöld test
- improved ankle dorsiflexion with knee flexed = gastrocnemius tightness
- equivalent ankle dorsiflexion with knee flexion and extension= achilles tightness

TAG

(OBQ10.193) Which of the following best describes the physical examination test demonstrated in Figure A? Topic

Review Topic

FIGURES: A

1. Silfverskiöld test used to differentiate gastrocnemius tightness from achilles tendon contracture
2. Thompson test used to differentiate soleus tightness from achilles tendon contracture
3. Coleman test used to differentiate soleus tightness from achilles tendon contracture
4. Silfverskiöld test to differentiate soleus tightness from achilles tendon contracture
5. Thompson test to differentiate gastrocnemius tightness from achilles tendon contracture

PREFERRED RESPONSE ▶

DISCUSSION: The Silfverskiöld test differentiates gastrocnemius tightness from an achilles tendon contracture by evaluating ankle dorsiflexion with the knee extended and then flexed. Increased ankle dorsiflexion with knee flexion indicates gastrocnemius tightness. This occurs because the gastrocnemius relaxes with knee flexion as the muscle spans the knee joint and the soleus does not. If there is no difference in dorsiflexion with flexion of the knee, then an achilles tendon contracture is present.

REFERENCES:

1. Wenz W, Dreher T. Charcot-Marie-Tooth disease and the cavovarus foot. In: Pinzur MS, ed. Orthopaedic Knowledge Update: Foot and Ankle 4. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2008:291-306.

2. Hansen ST Jr. Evaluation and education of the patient. In: Hansen ST Jr, ed. Functional Reconstruction of the Foot and Ankle. Philadelphia, PA: Lippincott Williams & Wilkins; 2000:115-121.

Question Authors:

Michael Hughes MD,

Please Rate Educational Value!

4.0

Average 4.0 of 13 Ratings

TAG

(OBQ04.112) A 54-year-old male with Protein C deficiency sustained a stroke 3 months ago with subsequent left sided weakness. The patient's skin is intact with no sign of ulcerations or callosities. His left foot is developing a varus deformity secondary to a spastic tibialis anterior. His ankle has a 5 degree plantar flexion deformity due to a gastrocnemius contracture which improves with knee flexion (positive Silverskiold test). The patient has an intrinsic minus foot with supple claw toes present. Which of the following is the most appropriate next step in management? Topic

Review Topic

1. Gastrocnemius fascia lengthening (Strayer) procedure
2. Split anterior tibial tendon transfer (SPLATT)
3. 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
4. Fractional lengthening of the tibialis posterior
5. Ankle foot orthosis (AFO) with physical therapy

PREFERRED RESPONSE ▶

DISCUSSION: The key to this patient's presentation is the occurrence of the stroke only 3 months ago. Miller Review states at least a 6 month delay is required and the review article by Younger and Hansen state a delay of 18 to 24 months between cerebral injury and reconstructive surgery is advisable because of the possibility of various degrees of functional recovery. The critcial components to nonoperative management include AFO fitting, early intervention with physical therapy, stretching and strengthening, and maintenance of joint range of motion. Phenol or botox injections can also be useful nonsurgical adjuvants.
Equinovarus posturing is the most common ankle-foot abnormality following a stroke. The equinus component is caused by overactivity of the gastrocnemius-soleus complex. The varus is due to relative overactivity of the tibialis anterior, with contributions from the tibialis posterior, FHL, and FDL. Each of the surgical options are reasonable treatments for this patient's presentation if there had been an adequate interval between the patient's cerebral insult and he had failed conservative management.

REFERENCES:

1. Mann RA, Coughlin MJ, ed. Surgery of the Foot and Ankle, ed 6. St. Louis, MO, Mosby, 1993, pp 604-605

2. Younger AS, Hansen ST Jr. Adult cavovarus foot. J Am Acad Orthop Surg. 2005 Sep;13(5):302-15. PMID:16148356 (Link to Abstract)

Question Authors:

Michael Hughes MD,

Please Rate Educational Value!

3.0

Average 3.0 of 9 Ratings

Level of Evidence 5 and Other Journal Articles (includes Case Reports, Expert Opinions, Personal Observations, and Biomechanic Studies)

Mann RA, Coughlin MJ, ed. Surgery of the Foot and Ankle, ed 6. St. Louis, MO, Mosby, 1993, pp 604-605
Younger AS, Hansen ST Jr. Adult cavovarus foot. J Am Acad Orthop Surg. 2005 Sep;13(5):302-15. PMID:16148356 (Link to Abstract)

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012

Undefined

Wenz W, Dreher T. Charcot-Marie-Tooth disease and the cavovarus foot. In: Pinzur MS, ed. Orthopaedic Knowledge Update: Foot and Ankle 4. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2008:291-306.
Hansen ST Jr. Evaluation and education of the patient. In: Hansen ST Jr, ed. Functional Reconstruction of the Foot and Ankle. Philadelphia, PA: Lippincott Williams & Wilkins; 2000:115-121.

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