Lateral Ankle Sprains

High Yield Overview

Lateral Ankle Sprains

Inversion Injury | ATFL Rupture | Brostrom-Gould Repair

85%of all ankle sprains

20-40%develop chronic instability

98%Ottawa Rules sensitivity

85-95%Surgery success rate

Injury Grading

Grade I

PatternStretch, no macro tear, stable

TreatmentFunctional Rehab

Grade II

PatternPartial tear, mild laxity

TreatmentRehab + Bracing

Grade III

PatternComplete rupture, gross instability

TreatmentRehab (Acute) vs Surgery (Chronic)

Critical Must-Knows

ATFL is injured first in plantarflexion (weakest position)
Ottawa Ankle Rules reduce unnecessary X-rays by 30-40%
Functional rehab is superior to immobilization (Cochrane)
Brostrom-Gould repair is the Gold Standard for chronic instability
Rule out associated injuries: Maisonneuve, Base 5th MT, Osteochondral lesion

Examiner's Pearls

"
Don't offer surgery for acute sprains (even Grade III) - evidence supports conservation
"
Identify 'Mechanical' vs 'Functional' instability
"
Always palpate the proximal fibula (Maisonneuve fracture)
"
Prophylactic bracing reduces re-injury by 50%

Clinical Imaging

Imaging Gallery

Two-panel coronal MRI showing ankle ligament reconstruction with tendon graftCredit: Via Open-i (NIH) via Open-i (NIH) (Open Access (CC BY))

Arthroscopic view and diagram showing Brostrom repair with suture tape augmentationCredit: Via Open-i (NIH) via Open-i (NIH) (Open Access (CC BY))

Critical Exam Points

Ottawa Rules

Mandatory Knowledge. Know the 5 zones: Posterior edge/tip Lateral Malleolus, Medial Malleolus, Navicular, Base 5th MT, Weight bearing 4 steps.

Acute Management

Conservative First. Grade III acute ruptures heal well with functional rehab. Surgery is reserved for CHRONIC instability.

Must Not Miss

Associated Fractures. Maisonneuve (proximal fibula), Jones (Base 5th), Lisfranc (midfoot), Osteochondral lesion of Talus.

Surgical Standard

Brostrom-Gould. Anatomic repair of ATFL/CFL with retinaculum reinforcement. Avoid non-anatomic tenodesis.

At a Glance: Differential Diagnosis

Condition	Key Feature	Test	Management
Lateral Ankle Sprain	Inversion mech + ATFL tenderness	Anterior Drawer	Functional Rehab
Syndesmosis Injury	High ankle pain, dorsiflexion pain	Squeeze Test	Boot/TightRope
Fracture (Weber B)	Bony tenderness, unable to WB	X-ray (Ottawa)	ORIF vs Boot
Peroneal Dislocation	Snap/Pop, tendon subluxes	Resisted Eversion	Repair Retinaculum
Osteochondral Lesion	Deep pain, locking, persistent effusion	MRI	Debridement/Fixation

Mnemonic

AFPLigament Injury Sequence

Anterior Talofibular (ATFL)

First to tear (Plantarflexion)

Fibular Calcaneal (CFL)

Second to tear (Neutral/Dorsiflexion)

Posterior Talofibular (PTFL)

Last to tear (Dislocation)

Memory Hook:Anterior First in Plantarflexion.

Overview and Epidemiology

Lateral ankle sprains are the single most common musculoskeletal injury. While most heal uneventfully, a significant minority develop Chronic Ankle Instability (CAI), leading to recurrent giving way, pain, and potential post-traumatic arthritis.

Pathophysiology and Mechanisms

ATFL (Weakest Link)

Origin: Anterior distal fibula
Insertion: Lateral talar neck
Function: Resists anterior translation + inversion in plantarflexion
Thickness: Only 2mm (often just capsular thickening)
Injury: 85-90% of sprains

CFL (Stabilizer)

Origin: Fibula tip
Insertion: Lateral calcaneus
Function: Resists inversion in neutral/dorsiflexion
Course: Deep to peroneal tendons
Injury: 50-75% of severe sprains (usually with ATFL)

Critical Zone

The ankle is least stable in Plantarflexion. The wider anterior talus exits the mortise, relying entirely on ligaments (ATFL) for stability. This is why landing from a jump (plantarflexed foot) is the classic mechanism.

Classification Systems

Clinical Grading (Amalgamated)

Grade	Pathology	Clinical Findings	Stability	Rest
I (Mild)	Microscopic tear	Mild swelling, WB tolerated	Stable	1-2 weeks
II (Moderate)	Partial macroscopic tear	Moderate swelling, limp	Mild laxity	2-6 weeks
III (Severe)	Complete rupture	Severe swelling, Non-WB	Gross instability	6-12 weeks

Clinical Assessment

Mnemonic

CAMP BOttawa Ankle Rules (X-ray Indications)

Cannot weight bear

4 steps immediately & in ED

Anterior/Posterior Malleoli

Tenderness distal 6cm

Medial Malleolus

Tenderness tip/posterior edge

Posterior edge Lateral Malleolus

Tenderness tip/posterior edge

Base of 5th MT / Navicular

Foot tenderness zones

Memory Hook:Set up CAMP at the BASE of the mountain.

Examination Sequence

Lookswelling and deformity

Egg-shaped swelling over lateral malleolus (Haematoma sign). Check specifically for 'Too Many Toes' signs (pes planovalgus predisposes to instability).

FeelBony Tenderness

Rules out fractures: Fibula tip, Medial Mall, Base 5th MT, Navicular, Proximal Fibula (Maisonneuve).

MoveStability Tests

Anterior Drawer: Tests ATFL. (Positive greater than 3mm diff). Talar Tilt: Tests CFL. (Positive greater than 10deg or greater than 5deg diff). Squeeze Test: Syndesmosis.

Investigations

Standard Views: AP, Lateral, Mortise. Indications: Ottawa positive, inability to weight bear, high impact.

Management Algorithm

Clinical Algorithm

Loading flowchart...

Acute Management Gold Standard: Functional Rehabilitation (early motion + bracing) is superior to cast immobilization (Cochrane 2012). Immobilization should be reserved for severe pain or fractures, and limited to less than 10 days.

Surgical Technique

Modified Brostrom-Gould Repair

The Gold Standard Anatomic Repair.

Steps

ApproachAnterolateral Incision

Curvilinear incision anterior to fibula. Protect Superficial Peroneal Nerve (SPN) anteriorly.

ExposureIdentify ATFL

Open capsule. Identify widely stretched/torn ATFL/CFL remnants. Debride edges.

RepairAnatomic Plication

Place suture anchors (or transosseous tunnels) in distal fibula. Plicate ATFL/CFL in pants-over-vest fashion. Tighten in slight eversion/dorsiflexion.

GouldRetinaculum Augmentation

Mobilize Inferior Extensor Retinaculum. Advance superiorly over the repair. Increases strength and limits inversion (check subtalar motion).

Arthroscopic Brostrom repair with suture tape augmentation technique — Two-panel illustration of arthroscopic modified Brostrom repair with suture tape augmentation (internal brace) - (A) arthroscopic view showing first and second suture tape positions, (B) anatomical diagram demonstrating suture tape configuration providing checkrein reinforcement over native ligament repairCredit: Via Open-i (NIH) (Open Access (CC BY))

Complications

Nerve Injury

Superficial Peroneal Nerve: Most common (5-10%). Crossing branches in subcutaneous tissue.
Sural Nerve: Risk with posterior dissection for CFL.

Recurrence

Instability: 5-10% failure rate.
Stiffness: Overtightening causes loss of inversion/subtalar motion.

Wound

Dehiscence: Thin skin over lateral malleolus.
Infection: less than 1%.

Missed Mathology

Persistent Pain: Missed OCL, sinus tarsi syndrome, or peroneal tear.

Postoperative Care

Rehab Protocol

0-2 WeeksImmobilization

Backslab/Moonboot. Non-weight bearing or PWB. Wound healing priority.

2-6 WeeksProtection

CAM Boot. Start ROM (dorsiflexion/plantarflexion). Avoid inversion. Peroneal strengthening.

6-12 WeeksStrengthening

Lace-up brace. Proprioception training (balance board). Progress to jogging.

3-4 MonthsReturn to Sport

Sport-specific drills. Pass functional tests (Hop test).

Mnemonic

PMSFRehab Phases

Protection

0-2 wks: Boot, RICE

Motion

2-4 wks: ROM, Isometric

Strengthening

4-6 wks: Peroneals, Balance

Function

6+ wks: Plyometrics, Sport

Memory Hook:Please Make Sure Function returns.

Outcomes and Prognosis

Treatment	Success Rate	Return to Sport	Complications
Functional Rehab (Acute)	80-90%	2-6 weeks	20% Chronic Instability
Brostrom Repair	90-95%	3-4 months	5% Nerve Injury
Tenodesis (Non-anatomic)	70-80%	4-6 months	Stiffness/DJD

Evidence Base

Functional Rehab vs Immobilization

Kerkhoffs et al. • Cochrane Database 2012

Key Findings:

Functional treatment results in faster return to work/sport compared to immobilization
Less persistent swelling and instability
Highest evidence supports early motion + external support (brace/tape)

Clinical Implication: Treat acute sprains with early motion and bracing, not cast immobilization.

Brostrom vs Tenodesis

Hennrikus et al. • Am J Sports Med 2002

Key Findings:

Brostrom-Gould achieved higher functional scores (91 vs 82)
Fewer complications with Brostrom
Tenodesis associated with greater stiffness and subtalar degeneration
Confirmation of anatomic repair as gold standard

Clinical Implication: Brostrom-Gould is the gold standard; avoid non-anatomic tenodesis as first-line surgery.

Prophylactic Bracing

Verhagen et al. • BMJ 2000

Key Findings:

Prophylactic ankle support (bracing/taping) reduces incidence by 47%
Effect stronger in those with previous history (63% reduction)
Number Needed to Treat (NNT) = 5 to prevent one sprain

Clinical Implication: Mandate prophylactic bracing for all athletes with prior ankle sprains returning to sport.

Acute Surgery vs Conservation

Pihlajamaki et al. • JBJS Am 2010

Key Findings:

RCT of 51 young athletes with acute Grade III
No difference in instability, return to sport, or satisfaction at 9 years
Surgery group had more complications
Supports conservative management for ACUTE extra-articular injuries

Clinical Implication: Do not operate on acute Grade III sprains; conservative management is equally effective with fewer complications.

Brostrom Success Rate

Hale et al. • J Foot Ankle Surg 2007

Key Findings:

Systematic Review pooling 87-95% success rates
Return to sport 85%
Low complication rate (under 10%)
Superior to non-anatomic procedures

Clinical Implication: Counsel patients that Brostrom repair has 90% success rate with 85% return to sport.

Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Acute Ankle Sprain in Athlete

EXAMINER

"25yo AFL player, inversion injury 3 days ago. Swollen, positive anterior drawer. Previous sprains. Wants to play finals."

EXCEPTIONAL ANSWER

This is a Grade II/III injury. Management is initially conservative but aggressive (RICE to Functional Rehab). Rushing return carries 3-5x re-injury risk. I would assess function (hop test). If he plays, MANDATORY taping/bracing is required (reduces risk 50%). Long term, he risks chronic instability and may need off-season stabilization.

KEY POINTS TO SCORE

Grade assessment

Functional criteria for RTP

Prophylactic bracing (Evidence)

Short term gain vs long term risk

COMMON TRAPS

✗Allowing play without passing functional tests

✗Missing syndesmosis injury

✗Ignoring previous history

LIKELY FOLLOW-UPS

"What brace would you use?"

"When would you operate acutely?"

VIVA SCENARIOStandard

Chronic Instability Management

EXAMINER

"28F, recurrent sprains x4/year. Fails physio. MRI shows ATFL tear. Normal alignment."

EXCEPTIONAL ANSWER

Diagnosis is Chronic Ankle Instability (Mechanical). She has failed conservative care. I would offer Modified Brostrom-Gould repair. It is an anatomic repair using local tissue. I would augment with retinaculum. Success rate is 90%. Key risk to consent is nerve injury (SPN) and failure (5-10%).

KEY POINTS TO SCORE

Indication: Mechanical instability + Failed Rehab

Procedure: Brostrom-Gould

Success: 90%

Anatomy: ATFL/CFL

COMMON TRAPS

✗Proposing tenodesis (Chrisman-Snook) primarily

✗Failing to check hindfoot alignment (Varus predisposes to failure)

✗Missing hyperlaxity

LIKELY FOLLOW-UPS

"She has Ehlers-Danlos. Does this change your plan?"

" How do you examine for Generalized Laxity?"

VIVA SCENARIOAdvanced

Examiner Challenge - Surgical Technique

EXAMINER

"Describe your Brostrom-Gould technique. Where are the dangers? How do you set tension?"

EXCEPTIONAL ANSWER

I use a curvilinear anterolateral incision, protecting the superficial peroneal nerve anteriorly. I identify the ATFL/CFL remnants. I place suture anchors in the distal fibula (1cm proximal to tip). I perform a pants-over-vest imbrication of the ligaments. I tension in slight eversion and neutral dorsiflexion to avoid stiffness. Finally, I advance the extensor retinaculum (Gould) superiorly for augmentation. Key danger is the SPN.

KEY POINTS TO SCORE

Nerve protection (SPN)

Anchor placement

Tensioning position (Neutral/Eversion)

Gould modification

COMMON TRAPS

✗Tensioning in inversion (recreates laxity)

✗Tensioning in plantarflexion (causes stiffness)

✗Cutting the SPN

LIKELY FOLLOW-UPS

"What if the tissue is poor?"

"Role of Internal Brace?"

MCQ Practice Points

Nerve Injury

Q: What is the most common complication of Brostrom repair? A: Superficial Peroneal Nerve (SPN) injury (neurapraxia or injury). It runs in the subcutaneous tissue superficial to the extensor retinaculum.

Ottawa Specifics

Q: Which malleolar zones require X-ray according to Ottawa rules? A: Posterior edge or tip of medial/lateral malleolus (distal 6cm). Tenderness anterior to the malleolus (ATFL site) does NOT mandate X-ray.

Varus Malalignment

Q: What is the primary cause of Brostrom failure? A: Unrecognized Hindfoot Varus. The deformity places constant strain on the repair. A calcaneal osteotomy may be required.

Ligament Injury Sequence

Q: In what order do the lateral ankle ligaments tear with increasing force? A: ATFL → CFL → PTFL. The ATFL is weakest (2mm thick, essentially capsular thickening) and tears first in plantarflexion. The CFL tears second in neutral/dorsiflexion. The PTFL only tears with complete dislocation (strongest ligament).

Chronic Instability Definition

Q: How do you differentiate mechanical vs functional ankle instability? A: Mechanical instability = objective laxity on examination (positive Anterior Drawer/Talar Tilt). Functional instability = subjective giving way without gross laxity (proprioceptive/neuromuscular deficit). Treatment differs: functional requires rehab; mechanical may need surgical reconstruction if rehab fails.

Australian Context

Sports Stats

AFL/NRL: Lateral ankle sprain is the #1 most common injury. Bracing is mandatory for RTP in most clubs.