Lateral Ankle Sprains

High-yield overview

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

Clinical 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

A	Anterior Talofibular (ATFL) First to tear (Plantarflexion)
F	Fibular Calcaneal (CFL) Second to tear (Neutral/Dorsiflexion)
P	Posterior Talofibular (PTFL) Last to tear (Dislocation)

A	Anterior Talofibular (ATFL) First to tear (Plantarflexion)
F	Fibular Calcaneal (CFL) Second to tear (Neutral/Dorsiflexion)
P	Posterior Talofibular (PTFL) Last to tear (Dislocation)

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)

C	Cannot weight bear 4 steps immediately & in ED
A	Anterior/Posterior Malleoli Tenderness distal 6cm
M	Medial Malleolus Tenderness tip/posterior edge
P	Posterior edge Lateral Malleolus Tenderness tip/posterior edge
B	Base of 5th MT / Navicular Foot tenderness zones

C	Cannot weight bear 4 steps immediately & in ED	P	Posterior edge Lateral Malleolus Tenderness tip/posterior edge
A	Anterior/Posterior Malleoli Tenderness distal 6cm	B	Base of 5th MT / Navicular Foot tenderness zones
M	Medial Malleolus Tenderness tip/posterior edge

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 Pathology

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

P	Protection 0-2 wks: Boot, RICE
M	Motion 2-4 wks: ROM, Isometric
S	Strengthening 4-6 wks: Peroneals, Balance
F	Function 6+ wks: Plyometrics, Sport

P	Protection 0-2 wks: Boot, RICE	S	Strengthening 4-6 wks: Peroneals, Balance
M	Motion 2-4 wks: ROM, Isometric	F	Function 6+ wks: Plyometrics, Sport

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

Controversies & Areas of Uncertainty

Arthroscopic vs Open Brostrom

Arthroscopic repair shows comparable stability with faster early weightbearing, but there are no long-term trials. Open Brostrom-Gould remains the reference standard until durable data emerge.

Internal Brace / Suture Tape

Augmentation may permit accelerated rehabilitation and protect weak tissue, but adds cost and a non-anatomic, stiffer construct. Best evidence is for revision, hyperlaxity, high-demand athletes and obesity, not routine primary repair.

Surgery After Acute Grade III

Pihlajamaki's RCT showed lower reinjury after acute repair but more osteoarthritis. The balance of evidence still favours functional treatment first, with surgery reserved for failure.

Routine MRI

MRI is over-used acutely. It is reserved for persistent pain (over 6 weeks), suspected osteochondral lesion or peroneal pathology, and pre-operative planning, not for diagnosing a simple sprain.

Evidence Base

Functional Treatment vs Immobilisation (Cochrane)

Kerkhoffs GMMJ, Rowe BH, Assendelft WJJ, et al. • Cochrane Database Syst Rev 2013;(3):CD003762 (2013)

Key Findings:

21 trials, 2184 participants; functional treatment favoured over immobilisation
More patients returned to sport long-term (RR 1.86, 95% CI 1.22-2.86) and returned to work sooner (WMD 8.2 days)
Less persistent swelling and less objective instability on stress X-ray with functional treatment
Caveat: several differences lose significance when low-quality trials are excluded; this Cochrane review has since been withdrawn pending update, but its functional-over-immobilisation conclusion remains consistent with current society guidance

Clinical Implication: Treat acute lateral sprains with early functional rehabilitation (motion plus external support), not prolonged cast immobilisation.

Verify on PubMed (PMID 23543522)

Anatomic Repair vs Tenodesis (RCT)

Hennrikus WL, Mapes RC, Lyons PM, Lapoint JM • Am J Sports Med 1996;24(4):400-4 (1996)

Key Findings:

Prospective randomised trial of 40 patients with chronic lateral instability
Both procedures gave good or excellent stability in over 80% of patients
Modified Brostrom achieved significantly higher Sefton functional scores than Chrisman-Snook
Significantly more complications occurred after the non-anatomic Chrisman-Snook tenodesis

Clinical Implication: Anatomic modified-Brostrom repair is preferred over non-anatomic tenodesis as first-line surgery, with fewer complications.

Verify on PubMed (PMID 8827297)

Prevention of Recurrent Ankle Sprains

Verhagen EALM, Bay K • Br J Sports Med 2010;44(15):1082-8 (2010)

Key Findings:

Critical review of 24 studies on ankle sprain prevention
Taping, bracing and neuromuscular training all reduce recurrence (relative risks 0.2-0.5 vs control)
Benefit is driven by previously injured athletes; effect on first-ever sprains is minimal
Combining an external support (tape or brace) with neuromuscular training gives the best protection

Clinical Implication: Offer external bracing or taping plus proprioceptive/neuromuscular training to athletes with a prior ankle sprain returning to sport.

Verify on PubMed (PMID 21047837)

Acute Surgery vs Functional Treatment (RCT)

Pihlajamaki H, Hietaniemi K, Paavola M, Visuri T, Mattila VM • J Bone Joint Surg Am 2010;92(14):2367-74 (2010)

Key Findings:

RCT of 51 young active men with acute Grade III rupture; mean 14-year follow-up
All patients in both groups regained their pre-injury activity level; ankle scores and stress radiographs did not differ
Reinjury was less frequent after surgery (1/15 vs 7/18; risk difference 32%)
However Grade-II osteoarthritis was seen only in the surgical group (4/15 vs 0/18)

Clinical Implication: Functional treatment is the default for acute Grade III sprains; surgery may lower reinjury but carries a higher long-term osteoarthritis risk, so it is not first-line.

Verify on PubMed (PMID 20833874)

Arthroscopic vs Open Brostrom (Meta-analysis)

Attia AK, Taha T, Mahmoud K, Hunt KJ, Labib SA, d'Hooghe P • Orthop J Sports Med 2021;9(7):23259671211015207 (2021)

Key Findings:

8 comparative studies, 408 patients (193 open, 215 arthroscopic)
States that nearly 20% of acute sprains progress to chronic instability requiring surgery
Arthroscopic repair gave modestly higher AOFAS scores and faster weightbearing (mean 9.0 vs 14.25 weeks)
Complication rates, talar tilt and anterior drawer were comparable; open Brostrom-Gould remains the reference standard

Clinical Implication: Open modified Brostrom-Gould remains the benchmark; arthroscopic repair is a reasonable alternative in experienced hands with comparable complications and faster early recovery.

Verify on PubMed (PMID 34368381)

Society Guidance on Ankle Sprain Care

Guideline

AAOS / BOA-BOAST / ESSKA-AFAS consensus • National society guidance and expert consensus

Key Findings:

Use validated decision rules (Ottawa Ankle Rules) to limit unnecessary radiographs
Functional rehabilitation with early weightbearing and proprioceptive training is first-line for acute sprains
Reserve surgery for chronic mechanical instability that has failed structured rehabilitation
Recommend bracing/taping plus neuromuscular training for athletes with recurrent sprains

Clinical Implication: Align practice with society guidance: decision rules, functional rehabilitation first, surgery only for refractory chronic instability.

Viva Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

Acute Ankle Sprain in Athlete

CLINICAL PROMPT

"25yo professional field-sport athlete, inversion injury 3 days ago. Swollen, positive anterior drawer. Previous sprains. Wants to play in the finals."

PRACTICAL APPROACH

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 CLINICAL POINTS

Grade assessment

Functional criteria for RTP

Prophylactic bracing (Evidence)

Short term gain vs long term risk

COMMON PITFALLS

Allowing play without passing functional tests

Missing syndesmosis injury

Ignoring previous history

FURTHER QUESTIONS

"What brace would you use?"

"When would you operate acutely?"

CLINICAL SCENARIOStandard

Chronic Instability Management

CLINICAL PROMPT

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

PRACTICAL APPROACH

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 CLINICAL POINTS

Indication: Mechanical instability + Failed Rehab

Procedure: Brostrom-Gould

Success: 90%

Anatomy: ATFL/CFL

COMMON PITFALLS

Proposing tenodesis (Chrisman-Snook) primarily

Failing to check hindfoot alignment (Varus predisposes to failure)

Missing hyperlaxity

FURTHER QUESTIONS

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

" How do you examine for Generalized Laxity?"

CLINICAL SCENARIOAdvanced

Examiner Challenge - Surgical Technique

CLINICAL PROMPT

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

PRACTICAL APPROACH

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 CLINICAL POINTS

Nerve protection (SPN)

Anchor placement

Tensioning position (Neutral/Eversion)

Gould modification

COMMON PITFALLS

Tensioning in inversion (recreates laxity)

Tensioning in plantarflexion (causes stiffness)

Cutting the SPN

FURTHER QUESTIONS

"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.

Guidelines, Registries & Global Practice

Global epidemiology. Lateral ankle sprain is the single most common musculoskeletal injury worldwide, with an estimated incidence of about 2-7 per 1000 person-years in the general population and far higher in court/jumping and field sports (basketball, volleyball, football/soccer). Around 40% present to emergency or primary care. Roughly 1 in 5 (about 20%) progress to chronic ankle instability with recurrent giving-way. There is no implant registry for soft-tissue ankle ligament surgery, so the evidence base is RCTs, cohorts and meta-analyses rather than national registries.

Side-by-Side Guideline Comparison

Body / Region	Imaging	Acute Treatment	Surgery
Ottawa Rules (validated globally)	X-ray only if bony tenderness or unable to weight bear 4 steps	n/a	n/a
AAOS / US sports medicine	Selective radiographs; MRI for persistent pain	Functional rehab, early weightbearing, proprioception	Chronic mechanical instability after failed rehab
BOA / NICE (UK)	Ottawa Rules to limit X-rays	RICE then early functional rehab; brief support	Reserved for refractory chronic instability
ESSKA-AFAS / EFORT (Europe)	Stress US/MRI in chronic cases	Functional rehab; bracing for high-risk return	Anatomic repair (Brostrom-Gould) first-line

High-Resource Settings

Ready access to MRI and ultrasound, supervised physiotherapy, suture-anchor and internal-brace constructs, and increasing use of arthroscopic Brostrom in specialist centres.

Limited-Resource Settings

Greater reliance on Ottawa Rules and clinical examination, functional rehabilitation with low-cost bracing/taping, and transosseous (drill-hole) Brostrom repair where suture anchors are unavailable. Outcomes of anatomic repair remain good without expensive implants.