Ankle Instability

By admin Last updated Jan 2, 2024

Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.

Title: 5-Minute Orthopaedic Consult, 2nd Edition

> Table of Contents > Ankle Instability

Ankle Instability

Dennis E. Kramer MD

Basics

Description

Recurrent ankle sprains occurring
primarily from an inversion stress on a plantarflexed ankle, which lead
to chronic ankle pain and instability
Divided into 2 types:
- Functional instability:
  - Pain causes ankle to be unstable.
  - Feeling of ankle “giving way”
  - Neuromuscular deficit
- True mechanical instability:
  - Frank insufficiency of ligaments
  - Physiologic ROM is exceeded.
  - Positive anterior drawer or talar tilt test

General Prevention

Treat initial ankle sprains aggressively using:
- Activity modification
- Bracing
- Functional rehabilitation program

Epidemiology

Incidence

Ankle sprains account for as many as 40% of all athletic injuries (1).
27,000 ankle sprains occur each day in the United States (2).
Symptomatic ankle instability will develop in up to 20% of patients after an inversion sprain of the lateral ankle ligaments (3).

Prevalence

High in soccer and basketball players

Risk Factors

History of previous sprain (most common risk factor)
Connective-tissue disorders
Cavovarus foot alignment

Etiology

Complex causes of functional instability:
- Neural: Proprioception, reflexes, muscle reaction time
- Muscular: Strength, power, endurance
- Mechanical: Lateral ligamentous laxity
Ankle sprains cause sequential disruption of:
- Anterolateral joint capsule
- ATFL
- CFL
Primary static restraints to ankle inversion injury:
- ATFL:
  - Most commonly injured ankle ligament
  - Primary restraint to inversion with ankle plantarflexed
  - Torn in inversion, plantarflexion, and internal rotation
- CFL:
  - Stabilizes ankle and subtalar joints
  - Resists inversion with ankle dorsiflexed
  - Tears in inversion and dorsiflexion
Primary dynamic restraints:
- Peroneal tendons
Key anatomy:
- ATFL:
  - Originates 1 cm proximal to tip of lateral malleolus
  - Inserts into talus 18 mm superior to subtalar joint, coursing anteriorly at a 90° angle to fibula
  - 7 mm wide, 10 mm long
  - Intimately associated with joint capsule
- CFL:
  - Originates adjacent to the ATFL, 8 mm proximal to tip of fibula
  - Courses at a 130° angle to the fibula,
    heading posteriorly and distally to insert on the calcaneus 13 mm
    distal to subtalar joint
  - Extracapsular: Floor of peroneal sheath
- Posterior talofibular ligament: Rarely injured except with ankle dislocations

Associated Conditions

Connective-tissue disorders: Ehlers-Danlos

Diagnosis

Must differentiate functional from mechanical instability.
15–30% of simple ankle sprains result in residual symptoms with peroneal weakness (functional instability) (3,4).

Signs and Symptoms

Recurrent ankle pain and swelling

History

Recurrent sprains with minimal trauma
Subjective feeling of ankle “giving way”
Repeated episodes of instability with asymptomatic periods between episodes

Physical Exam

Assess hindfoot alignment.
Evaluate gait.
Neurovascular examination: Increased superficial peroneal nerve injuries in patients with recurrent ankle sprains
Palpate peroneal tendons.
Assess ankle ROM.
- Crepitus and pain with ROM may be indicative of cartilaginous injury.
Assess subtalar motion.
- Rigidity may suggest tarsal coalition.
Assess subtalar stability.
- Assess CFL integrity.
- Dorsiflex ankle and apply inversion force to calcaneus.
- Medial translation of calcaneus is indicative of subtalar instability.
Evaluate for mechanical instability.
- Anterior drawer test:
  - Evaluates ATFL
  - Position ankle in neutral and apply anterolateral force to heel.
  - Positive test: >10 mm of anterior
    translation on involved side, >3 mm of anterior translation greater
    than on uninvolved side; confirm with lateral stress radiograph.
- Talar tilt test:
  - Evaluates CFL
  - Patient seated, ankle neutral
  - Apply inversion force to hindfoot and midfoot as a unit.
  - Do not allow forefoot to rotate medially.
  - Positive test: Talar tilt >9° total,
    talar tilt 3° more on involved than uninvolved side; confirm on stress
    mortise radiograph.

Tests

Imaging

Lateral and mortise radiographs:
- Posttraumatic changes:
  - Tibial marginal osteophytes
  - Talar exostoses (at ATFL insertion)
  - Osteochondral lesions of talus
  - Os subfibulare
Mortise and lateral stress radiographs:
- Anterior translation (assesses ATFL):
  - Measured on lateral stress radiograph
  - Perpendicular distance between posterior edge of tibial articular surface and talus
  - Anterior translation 3–5 mm more than other side or 10 mm absolute is indicative of mechanical instability.
- Talar tilt (assesses CFL):
  - Measured on mortise stress view
  - Angle between tibial and talar surfaces
  - Talar tilt angle 3–5° more than the other side or 10° absolute is indicative of mechanical instability.

Differential Diagnosis

Ankle pain may be associated with ankle instability.
Other causes of ankle pain include (2,5):
- Intra-articular fibrosis/synovitis
- Talus OATS
- Peroneal tendon tears
- Peroneal tendon subluxation
- Lateral process of talus fracture

P.21

Treatment

General Measures

Initial treatment for ankle instability is nonoperative.
- RICE protocol
- Ankle brace:
  - Moderate to severe sprains may be braced for 6 months to allow return to sports.
- Functional rehabilitation
- Residual lateral ankle pain and functional instability most often are secondary to inadequate rehabilitation.

Activity

Restrict sports until:
- Rehabilitation program is completed.
- Strength and ROM are normal.
- Patient is able to perform sport-specific tasks (cutting, jumping).
Functional bracing or taping during return to athletics may help prevent recurrence.
- Braces do not interfere with performance.

Special Therapy

Physical Therapy

Should emphasize:
- ROM, concentric and eccentric muscle strengthening
- Endurance training of peroneals
- Proprioception
- Tilt-board exercises

Surgery

Indications for surgery:
- Persistent instability after a functional rehabilitation program
- Extreme laxity
- Recurrent sprains with normal activities
- Instability with sports despite bracing/taping
Surgical techniques:
- Anatomic repair:
  - Best results for patients with good-quality soft tissues
  - Benefits: Restores normal anatomy, preserves subtalar motion, preserves peroneals (dynamic stabilizers)
  - Contraindications: Connective-tissue
    disorder (Ehlers-Danlos), failed previous surgery, severely attenuated
    tissue (>10 years of instability)
  - Broström repair (6): Direct late repair, torn ends of ATFL shortened and repaired; sometimes CFL imbrication is necessary
  - Gould modification (7):
    Immobilization and reattachment of inferior extensor retinaculum to
    fibula after imbrication of ATFL and CFL; provides additional stability
  - Combination of Broström and Gould technique is the gold standard, with 90% success rate (8).
- Reconstruction (Chrisman-Snook, Evans):
  - Indications: Patient with poor-quality
    soft tissue (ligaments are attenuated), salvage for a failed Broström
    procedure, obesity/high-demand patient
  - Benefits: Increased strength of repair
  - Problems: Nonanatomic reconstruction, loss of talocrural and subtalar motion, adjacent peroneal nerve injury
  - Chrisman-Snook reconstruction (9):
    Split peroneus brevis at its attachment to base of 5th metatarsal;
    harvest proximal portion of split peroneus brevis and weave it anterior
    to posterior through a drill hole in fibula; then weave it posterior to
    anterior through a calcaneal bone tunnel; suture it back to itself.
  - Evans reconstruction (10):
    Harvest proximal portion of peroneus brevis; weave it anterior to
    posterior through a fibular drill hole; does not address subtalar
    instability
- Realignment procedures: Hindfoot varus— calcaneal osteotomy can be performed in conjunction with repair or reconstruction.

Follow-up

Postoperatively:
- Cast in eversion for 2–6 weeks
- Then switch to removable brace
- Physical therapy for 3 months
- Protective brace for at least 6 months

Prognosis

High success rate regardless of anatomic repair or tenodesis procedure (1)
Predictors of poor outcome after surgery:
- ≥10 years of symptoms
- Ankle osteoarthritis
- Joint hypermobility

Complications

Highest percentage occur in nonanatomic reconstruction procedures
- Loss of subtalar and talocrural motion
- Peroneal nerve injury
- Tendon failure: Tendons are stiffer and have less strain to failure than ligaments.

References

1. Colville MR. Surgical treatment of the unstable ankle. J Am Acad Orthop Surg 1998;6:368–377.

2. Renstrom PAFH. Persistently painful sprained ankle. J Am Acad Orthop Surg 1994;2:270–280.

3. Freeman MAR. Instability of the foot after injuries to the lateral ligament of the ankle. J Bone Joint Surg 1965;47B:669–677.

4. Gerber
JP, Williams GN, Scoville CR, et al. Persistent disability associated
with ankle sprains: a prospective examination of an athletic
population. Foot Ankle Int 1998;19:653–660.

5. Digiovanni BF, Fraga CJ, Cohen BE, et al. Associated injuries found in chronic lateral ankle instability. Foot Ankle Int 2000;21:809–815.

6. Broström L. Sprained ankles. VI. Surgical treatment of “chronic” ligament ruptures. Acta Chir Scand 1966;132:551–565.

7. Gould N, Seligson D, Gassman J. Early and late repair of lateral ligament of the ankle. Foot Ankle 1980;1:84–89.

8. Bell SJ, Mologne TS, Sitler DF, et al. Twenty-six-year results after Broström procedure for chronic lateral ankle instability. Am J Sports Med 2006;34:975–978.

9. Snook
GA, Chrisman OD, Wilson TC. Long-term results of the Chrisman-Snook
operation for reconstruction of the lateral ligaments of the ankle. J Bone Joint Surg 1985;67A:1–7.

10. Evans DL. Recurrent instability of the ankle—a method of surgical treatment. Proc R Soc Med 1953;46:343–344.

Additional Reading

Baumhauer JF, O’Brien T. Surgical considerations in the treatment of ankle instability. J Athletic Training 2002;37:458–462.

Girard
P, Anderson RB, Davis WH, et al. Clinical evaluation of the modified
Broström-Evans procedure to restore ankle stability. Foot Ankle Int 1999;20:246–252.

Povacz
P, Unger F, Miller K, et al. A randomized, prospective study of
operative and non-operative treatment of injuries of the fibular
collateral ligaments of the ankle. J Bone Joint Surg 1998;80A:345–351.

Thacker SB, Stroup DF, Branche CM, et al. The prevention of ankle sprains in sports. A systematic review of the literature. Am J Sports Med 1999;27:753–760.

Miscellaneous

Codes

ICD9-CM

718.87 Ankle instability

Patient Teaching

Activity

Modify activities until appropriate rehabilitation program is completed.

Prevention

Brace may prevent recurrence during athletics.

FAQ

Q: Does the patient have functional or mechanical instability?

A: Check anterior drawer and talar tilt test to document presence or absence of mechanical instability.

Q: What are the initial treatment recommendations for a patient presenting with functional ankle instability?

A:
Activity modification, ankle brace, functional rehabilitation program
focusing on proprioception and endurance training of peroneals.

Q: What is the gold standard initial surgery for mechanical ankle instability in a healthy athlete?

A: An anatomic repair procedure such as the Broström repair with Gould modification.