Lower Leg Injuries and Nerve Damage

Ankle Injury Assessment and Diagnosis

Patient Presentation

• Patient reports pain as a 10/10.

• Pronounced limp and unwillingness to bear weight on the affected foot.

• Pain during active and passive range of motion, especially with varus stress or eversion.

Initial Assessment

• Plain film radiograph ordered to assess the injury.

Soft Tissue Involvement

• Question: What soft tissue is directly involved in this injury?

• Options:

  • Fibularis brevis or longus

  • Flexor hallucis longus

  • Lateral collateral ligament of the ankle

  • Medial collateral ligament

  • Plantar aponeurosis

  • Tibialis posterior muscle

• The correct answer is Fibularis brevis.

Fibularis Brevis Injury

• The tendon inserts on the fifth metatarsal.

• Avulsion fracture can occur at the base of the fifth metatarsal.

Types of Fractures at the Base of the Fifth Metatarsal

• Avulsion Fracture: At the tip of the base.

• Jones Fracture: Further in, around the remnant of the growth plate.

  • Note: Differentiating between avulsion and Jones fracture not required for exams.

• Stress Fracture: Due to repetitive overuse; ligament is intact.

Os Peroneum

• Vestigial sesamoid bone that can be misdiagnosed as a fracture.

• Patient history and physical assessment are important for accurate diagnosis.

Treatment of Fibularis Brevis Avulsion Fracture

• Conservative treatment: Ankle brace or boot to allow healing.

• The bone will refuse over time if not constantly pulled on.

Avulsion Fracture and Tendon Retraction

• Unlike a biceps rupture, the tendon doesn't pull back significantly due to retinaculum and tight space.

• Assessment focuses on point tenderness at the base of the fifth metatarsal.

Shin Splints and Related Conditions

Case Presentation: Cross Country Athlete

• 16-year-old high school cross country athlete.

• Dull, aching pain at the front of the leg, greatest after training, relieved by rest.

• Training on indoor track during winter months.

• X-ray ordered.

Question: Soft Tissue Involvement

• What soft tissue structure is most likely involved in the patient's injury?

• Options:

  • Extensor digitorum longus or hallucis longus

  • Tibialis brevis or longus muscles

  • Medial collateral ligament at the ankle

  • Flexor digitorum longus or hallucis longus

  • Tibialis anterior or posterior muscles

• The correct answer is Tibialis Posterior.

Shin Splints - Tibialis Posterior Involvement

• Commonly associated with sprint training on hard surfaces.

• During foot plant, weight pushes the heel down; dorsiflexors contract eccentrically to slow the weight, then concentrically for a forceful sprint.

• Eccentric contractions generate more force than concentric contractions, leading to microtrauma.

• Tibialis anterior (dorsiflexor) is less engaged in this activity.

Eccentric Contractions and Hypertrophy

• Focusing on eccentrics with resistance training may stimulate hypertrophy, though research is inconclusive.

Location of Pain

• Pain is felt at the front of the leg due to inflammation of the interosseous membrane.

• The tibialis posterior is in the deep posterior compartment, but the interosseous membrane is closer to the front.

Treatment Considerations

• Ice application: Apply to the front of the leg to target the inflamed interosseous membrane.

• Bone is a strong conductor of heat; cooling the tibia helps cool the interosseous membrane.

• Rehab focus: Stretching the affected muscle (plantar flexor) by pushing into dorsiflexion.

• Gradual progression to avoid re-tearing tissue.

Factors related to activity

• Individuals can stretch by sitting or standing position.

Case Presentation: Shin Splints in Cross Country Athlete

• 20-year-old cross country athlete with shin splints that bother her ~15 minutes into training.

• Examination reveals nothing significant initially.

• Reports pain and tightness after training and showering.

• Mentions tripping a lot late into training sessions.

• Active and resistive ROM are painful but normal.

• Passive ROM is limited due to pain.

• Capillary refill test is normal.

• Sensory test reveals numbness in the webbing between the first two toes.

Question: Chief Medical Condition

• Options:

  • Terrible triad

  • Complete lesion in the common fibular nerve

  • Excessive pressure in the anterior or lateral compartments

  • Deep fibular nerve lesion

  • Distal talofibular joint ligament tear

  • Fibular fracture

  • Lateral or medial ankle ligament tears

  • Superficial fibular nerve lesion

• The correct answer is Excessive pressure in the anterior compartment

Anterior Compartment Syndrome

• Key Point: Symptoms present after training and showering, suggesting transient pressure increase.

• Muscle pump and edema during exercise increase pressure.

• Resting reduces pressures, re-establishing blood flow, but sensory neurons may still be affected.

• The key with this case is that the capillary refill test is normal.

Sensory vs Motor Neurons

• Sensory neurons are more susceptible to pressure due to smaller diameter.

• Motor neurons have a larger diameter and require more pressure to be affected.

Sensitivity and Specificity of Tests

• Even the best tests have false negatives.

• Clinical practice requires considering all evidence to determine the most likely diagnosis.

Chronic Exertional Anterior Compartment Syndrome

• Exercise-induced pain that goes away at rest.

• Can be asymptomatic at rest.

• Tightness, cramping, and dull aching.

Compartment Syndrome: Personal Accounts

• Maddie: Anterior, lateral, and posterior compartment syndrome; pain with minimal activity; treated with fasciotomy.

• Steph: Compartment syndrome in all four compartments; misdiagnosed as shin splints; had anterior and lateral release, but symptoms returned in the posterior part of calves.

Acute vs Chronic Compartment Syndrome

• Anterior and lateral compartments are more concerning due to limited space; swelling can lead to ischemia and necrosis.

• Posterior compartments have more volume but can still cause issues.

• Conservative treatment is typically not successful; fasciotomy has a higher success rate.

• Easy to misdiagnose; pain presents like shin splints.

Nerve Injuries

Case Presentation: Jalen Smith Injury

• Jalen Smith suffered ACL and LCL tear during hyperextension.

• Difficulty lifting toes while heading off the field.

• Numbness along the lateral aspect of the left leg and dorsum of the left foot.

Question: Nerve Damage

• What nerve was most likely damaged in the hyperextension injury?

• Options:

  • Common fibular

  • Deep fibular

  • Saphenous

  • Superficial fibular

  • Tibial

• The correct answer is Common fibular.

Common Fibular Nerve Injury

• Hypervarus force can stretch the common fibular nerve.

• Loss of sensation to the lateral leg and dorsum of the foot indicates superficial fibular nerve involvement.

• Loss of motor function to the dorsiflexors indicates deep fibular nerve involvement.

• Combined loss of sensation and motor function indicates common fibular nerve involvement.

Other Nerve Injuries

• Deep Fibular Nerve Lesion: Loss of dorsiflexion (drop foot); loss of sensation between the webbing of the two toes.

• Superficial Fibular Nerve Lesion: Diffuse loss of sensation on the lateral leg and dorsum of the foot.