ATFL Primary | CFL Secondary | Mechanical + Functional
Types of Instability
Critical Must-Knows
- ATFL is weakest and most commonly injured lateral ligament
- CFL is EXTRA-ARTICULAR - injured with increasing inversion force
- Anterior drawer tests ATFL; Talar tilt tests CFL
- Conservative treatment fails in 20-40% of patients
- Brostrom-Gould is gold standard surgical treatment
Clinical Pearls
- "ATFL: resists anterolateral translation in plantarflexion
- "CFL: resists inversion throughout ROM (crosses subtalar joint)
- "Functional instability = proprioceptive deficit, peroneal weakness
- "Always exclude subtalar instability and OLT
Clinical Imaging
Imaging Gallery
Critical Chronic Ankle Instability Exam Points
Anatomy is Key
ATFL (anterior talofibular): weakest lateral ligament, taut in plantarflexion, resists anterior translation. CFL (calcaneofibular): extra-articular, taut in dorsiflexion, crosses subtalar joint. PTFL: rarely injured, strongest lateral ligament.
Distinguish Instability Types
Mechanical instability = true laxity (positive anterior drawer greater than 10mm, talar tilt greater than 10 degrees). Functional instability = giving way without laxity (proprioceptive deficit, peroneal weakness). Both types can coexist.
Examination
Anterior drawer (ATFL): 90 degrees knee flexion, ankle neutral, translate talus anteriorly. Talar tilt (CFL): invert hindfoot, compare to contralateral. Compare side-to-side - absolute values less reliable.
Surgical Decision
Brostrom-Gould = anatomic repair + IER reinforcement (first line). Non-anatomic reconstruction (tenodesis) for revision, generalized laxity, or poor tissue. Graft reconstruction increasingly popular.
Quick Decision Guide
| Presentation | Examination | Imaging | Management |
|---|---|---|---|
| Giving way, no objective laxity | Normal drawer/tilt, weak peroneals | XR normal, consider MRI | 6 months proprioceptive rehab |
| Recurrent sprains, mild laxity | Positive drawer, minimal tilt | Stress XR equivocal | Trial bracing + rehab first |
| Frequent giving way, clear laxity | Positive drawer AND tilt | Stress XR positive | Surgical stabilization |
| Previous failed surgery | Positive exam, generalized laxity | MRI shows tissue quality | Graft reconstruction |
ACPLateral Ligament Complex
| A | ATFL (Anterior Talofibular) Weakest, most injured, intra-articular |
| C | CFL (Calcaneofibular) Extra-articular, crosses subtalar joint |
| P | PTFL (Posterior Talofibular) Strongest, rarely injured |
| A | ATFL (Anterior Talofibular) Weakest, most injured, intra-articular |
| C | CFL (Calcaneofibular) Extra-articular, crosses subtalar joint |
| P | PTFL (Posterior Talofibular) Strongest, rarely injured |
Hook:ACP = Anterior is weakest, Calcaneofibular is Central, Posterior is strongest!
PROPSCauses of Functional Instability
| P | Proprioceptive deficit Impaired joint position sense |
| R | Reflex delay Delayed peroneal reaction time |
| O | Omentic (muscle) weakness Peroneal and inverter weakness |
| P | Postural control deficit Balance impairment |
| S | Somatosensory changes Altered afferent input |
| P | Proprioceptive deficit Impaired joint position sense | P | Postural control deficit Balance impairment |
| R | Reflex delay Delayed peroneal reaction time | S | Somatosensory changes Altered afferent input |
| O | Omentic (muscle) weakness Peroneal and inverter weakness |
Hook:PROPS support the ankle - without them, it gives way!
BGTSurgical Options
| B | Brostrom (Modified Brostrom-Gould) Anatomic repair + IER reinforcement |
| G | Graft reconstruction Allograft or autograft (peroneus brevis, plantaris) |
| T | Tenodesis (non-anatomic) Evans, Chrisman-Snook, Watson-Jones |
| B | Brostrom (Modified Brostrom-Gould) Anatomic repair + IER reinforcement |
| G | Graft reconstruction Allograft or autograft (peroneus brevis, plantaris) |
| T | Tenodesis (non-anatomic) Evans, Chrisman-Snook, Watson-Jones |
Hook:BGT = Brostrom is Gold standard, Tenodesis for revisions!
Overview and Epidemiology
Chronic ankle instability (CAI) develops in 20-40% of patients following lateral ankle sprain. It is characterized by recurrent ankle sprains, episodes of giving way, and persistent symptoms lasting greater than 12 months despite conservative treatment. Athletes and active individuals are at highest risk.
Why Does Instability Develop?
Multifactorial: (1) Incomplete ligament healing with elongation/attenuation, (2) Proprioceptive deficit from mechanoreceptor damage, (3) Peroneal muscle weakness, (4) Altered neuromuscular control. Both mechanical and functional factors contribute.
Risk Factors
- Previous ankle sprain (strongest predictor)
- Inadequate initial treatment/rehab
- High-demand sports (basketball, soccer)
- Generalized ligamentous laxity
- Cavovarus foot alignment
Associated Conditions
- Osteochondral lesions of talus (15-25%)
- Subtalar instability
- Peroneal tendon pathology
- Anterior/posterior impingement
- Syndesmotic injury
Pathophysiology and Mechanisms
Critical Anatomy
The lateral ligament complex consists of three ligaments. The ATFL originates from anterior fibula and inserts on lateral talar body - it is the primary restraint against anterior translation in plantarflexion. The CFL is extra-articular, crosses the subtalar joint, and resists inversion throughout ROM.
Lateral Ankle Ligaments
| Ligament | Origin | Insertion | Injury Frequency | Function |
|---|---|---|---|---|
| ATFL | Anterior distal fibula | Lateral talar body | 85% (most common) | Resists anterior translation in PF |
| CFL | Distal fibula tip | Lateral calcaneus | 50-75% combined | Resists inversion, crosses STJ |
| PTFL | Posterior fibula | Posterior talus | Rare (5%) | Resists posterior translation in DF |
ATFL Biomechanics
ATFL taut in plantarflexion - this is why most ankle sprains occur with plantarflexion-inversion mechanism. ATFL provides 100% of resistance to anterior talar translation at 15 degrees plantarflexion. Sectioning ATFL increases anterior drawer by 4-5mm.
ATFL Details
- Length: 15-20mm, width: 7-8mm
- Weakest lateral ligament
- Intra-articular structure
- 3 distinct bands described
- Mean load to failure: 139N
CFL Details
- Length: 20-25mm, cord-like
- Extra-articular (key exam point)
- Crosses subtalar joint
- Overlapped by peroneal tendons
- Mean load to failure: 310N
Classification Systems
Mechanical vs Functional Classification
| Type | Definition | Examination | Treatment Focus |
|---|---|---|---|
| Mechanical | True ligamentous laxity | Positive drawer/tilt, stress XR abnormal | Surgical stabilization |
| Functional | Giving way without laxity | Normal exam, proprioceptive deficit | Proprioceptive rehabilitation |
| Combined | Both mechanical and functional | Laxity + neuromuscular deficit | Surgery + comprehensive rehab |
Clinical Significance
Functional instability can exist without mechanical laxity and responds well to rehabilitation. Mechanical instability requires structural restoration. Most patients with CAI have elements of both, requiring comprehensive management.
Classification guides treatment approach and rehabilitation focus.
Clinical Assessment
History
- Mechanism: Index injury and subsequent events
- Symptoms: Giving way, swelling, pain, difficulty on uneven ground
- Sports/Activity level: Demands and expectations
- Previous treatment: Bracing, rehab, surgery
Examination
- Inspection: Swelling, alignment (cavovarus)
- Palpation: ATFL, CFL, peroneal tendons, sinus tarsi
- ROM: Ankle and subtalar joint
- Stress tests: Anterior drawer, talar tilt
Complete Examination Required
Always assess: subtalar instability (Broden stress), peroneal tendon integrity (subluxation, tears), generalized ligamentous laxity (Beighton score), hindfoot alignment (cavovarus = higher recurrence), and contralateral ankle for comparison.
Clinical Tests for Lateral Ankle Instability
| Test | Technique | Positive Finding | Structure Tested |
|---|---|---|---|
| Anterior drawer | Stabilize tibia, translate talus anteriorly | Greater than 10mm or greater than 3mm vs contralateral | ATFL |
| Talar tilt | Stabilize tibia, invert hindfoot | Greater than 10 degrees or greater than 5 degrees asymmetry | CFL (+ ATFL if positive) |
| Inversion stress | Maximal inversion with ankle neutral | Pain, apprehension, increased motion | Lateral ligament complex |
| Peroneal test | Resist eversion, check for subluxation | Weakness, subluxation over malleolus | Peroneal tendons |
Comparison is Key
Absolute values are unreliable due to normal variability. Always compare to contralateral ankle. Asymmetry greater than 3mm (drawer) or greater than 5 degrees (tilt) is more significant than absolute measurements. Examine both ankles in the same position.
Differential Diagnosis of the "Giving-Way" Ankle
Recurrent giving way is NOT always lateral ligament instability. The exam favourite is the patient with normal stress tests whose true problem lies elsewhere - missing these is a classic viva trap.
Differential Diagnosis of Recurrent Ankle Giving Way
| Condition | Distinguishing Features | Best Test | Why It Mimics CAI |
|---|---|---|---|
| Lateral ligament (mechanical) instability | Positive drawer/tilt, plantarflexion-inversion mechanism | Stress radiographs, MRI | True ATFL/CFL laxity - the index diagnosis |
| Functional instability | Giving way, NORMAL stress tests, peroneal weakness | Balance/proprioception testing | Neuromuscular deficit without structural laxity |
| Subtalar instability | Sinus tarsi pain, hindfoot giving way, Broden views | Broden stress views, exam under anaesthesia | Often coexists; tilt may be falsely attributed to CFL |
| Peroneal tendon tear/subluxation | Posterolateral pain, snapping, weak eversion | Dynamic ultrasound, MRI | Peroneals are dynamic stabilizers - failure feels like instability |
| Osteochondral lesion of talus | Deep ankle pain, catching, effusion | MRI, arthroscopy | Catching/locking misread as giving way |
| Anterolateral soft-tissue impingement | Anterolateral pain on dorsiflexion, no laxity | MRI, diagnostic arthroscopy | Pain limits activity, mimics unstable ankle |
| Cavovarus / hindfoot malalignment | Visible varus, lateral overload, recurrent sprains | Weight-bearing alignment views, Coleman block | Structural varus drives recurrent inversion injury |
Investigations
Imaging Protocol
AP, lateral, and mortise views. Assess for malalignment, OLT, talar dome changes, arthritis. Weight-bearing views essential for alignment assessment. Often normal in isolated ligament injury.
Anterior drawer stress (Telos device) and inversion stress views. Quantify mechanical instability. Drawer greater than 10mm or tilt greater than 10 degrees (or asymmetry greater than 3mm/5 degrees) indicates instability.
Assess ligament quality, associated lesions (OLT, peroneal pathology, impingement), and tissue quality for surgical planning. Identifies chronic ligament changes (thickening, discontinuity, scarring).
Stress Radiograph Thresholds
Anterior drawer: greater than 10mm absolute or greater than 3mm asymmetry = ATFL incompetent. Talar tilt: greater than 10 degrees absolute or greater than 5 degrees asymmetry = ATFL + CFL involved. Always compare to uninjured side.
Radiographic Findings
- Stress XR: Quantify laxity
- Standard XR: Alignment, OLT, arthritis
- Broden stress: Subtalar instability
- Hindfoot alignment view: Cavovarus
MRI Findings
- ATFL: Thickened, attenuated, absent
- CFL: Integrity, scarring
- OLT: Location, size, stability
- Peroneal tendons: Tears, subluxation
Management Algorithm
Non-Operative Management Protocol
Goal: Restore proprioception, strength, and neuromuscular control.
Rehabilitation Phases
Acute management: RICE for any acute exacerbations. Ankle bracing for activity. Begin ROM exercises. Initiate proprioceptive training (single leg stance, wobble board).
Strengthening and proprioception: Progressive peroneal strengthening. Balance training progression. Sport-specific agility introduction. Continue bracing for activity.
Return to activity: Graduated return to sport. Continue proprioceptive maintenance. Brace use as needed. Monitor for recurrent symptoms.
Conservative Success Factors
60-80% success rate with comprehensive rehabilitation. Better outcomes with: functional instability only, good compliance, lower demands, and adequate peroneal strength. Failure indicators: mechanical laxity, cavovarus foot, high-demand athlete.
Minimum 6 months of supervised rehabilitation before considering surgery.
Surgical Technique
Modified Brostrom Procedure (Gold Standard)
Surgical Steps
Lateral decubitus or supine with bump. Thigh tourniquet. Mark landmarks: lateral malleolus, ATFL course, peroneal tendons, sinus tarsi.
Curvilinear incision anterior and distal to lateral malleolus (following ATFL). Identify and protect superficial peroneal nerve branches. Incise IER (inferior extensor retinaculum).
Identify ATFL (often attenuated, scarred). Assess CFL through same incision or separate distal limb. Evaluate tissue quality for repair vs reconstruction decision.
Incise ATFL capsule longitudinally at its talar attachment. Prepare fibular footprint with decortication. Pass suture anchors (2-3) into anterior fibula. Pants-over-vest imbrication of ATFL with ankle in neutral.
Key step: Advance IER (inferior extensor retinaculum) over ATFL repair and secure to fibula with sutures. This provides critical reinforcement and limits anterior translation.
If CFL involved, extend incision distally. Repair CFL to calcaneus with suture anchor or directly if tissue quality permits. Tension with ankle in neutral to slight eversion.
Technical Pearls
Tension repair with ankle in neutral - avoid over-tightening (causes stiffness) or under-tightening (recurrence). IER augmentation (Gould) is critical for improved outcomes. Consider arthroscopy first for OLT assessment and treatment.
Post-repair immobilization in walking boot for 2-4 weeks, then progressive weight-bearing and rehabilitation.
Complications
Potential Complications
| Complication | Risk Factors | Prevention | Management |
|---|---|---|---|
| Recurrent instability | Poor tissue quality, cavovarus, non-compliance | Proper patient selection, address alignment | Revision reconstruction with graft |
| Stiffness | Over-tensioning, prolonged immobilization | Appropriate tensioning, early ROM | Physiotherapy, possible MUA |
| Superficial peroneal nerve injury | Surgical approach | Careful dissection, identify nerve | Observation, most resolve |
| Wound complications | Diabetes, obesity, smoking | Meticulous technique, optimize health | Wound care, possible debridement |
| Subtalar stiffness (tenodesis) | Non-anatomic procedures | Use anatomic techniques | PT, accept some limitation |
Recurrence Risk Factors
Higher recurrence with: cavovarus foot (address surgically if significant), generalized ligamentous laxity (use graft augmentation), poor rehabilitation compliance, return to high-demand sport too early. Recurrence rate 5-15% even with modern techniques.
Cavovarus Foot
Cavovarus alignment places lateral ligaments at increased stress. If significant hindfoot varus present, consider calcaneal osteotomy (Dwyer) at time of ligament reconstruction to correct alignment and reduce recurrence risk.
Postoperative Care
Rehabilitation Protocol
Immobilization: Below-knee cast or controlled motion boot. Non-weight-bearing initially. Elevate, ice, wound care. Begin toe/knee ROM to prevent stiffness.
Protected mobilization: CAM boot weight-bearing as tolerated. Begin ankle ROM exercises out of boot. Avoid inversion initially. Start isometric strengthening.
Progressive loading: Wean from boot to supportive footwear. Progressive resistance training. Proprioception exercises. Gait training, stationary bike.
Return to activity: Sport-specific drills. Agility and plyometric progression. Criteria-based return to sport. Consider bracing for return.
Return Criteria
- Greater than 90% strength vs contralateral
- Full ROM without pain
- Passed functional hop tests
- Sport-specific drills tolerated
- Typically 4-6 months post-op
Bracing Post-Surgery
- Consider brace for first 6-12 months of sport
- May use permanently for high-demand activities
- Ankle support reduces re-injury risk
- Transition to tape if preferred
Outcomes and Prognosis
Outcomes by Procedure
| Procedure | Success Rate | Recurrence | Return to Sport |
|---|---|---|---|
| Brostrom-Gould (primary) | 85-95% | 5-10% | 85-90% |
| Anatomic graft reconstruction | 80-90% | 5-15% | 80-85% |
| Non-anatomic tenodesis | 70-80% | 10-20% | 70-80% |
| Revision surgery | 70-85% | 15-25% | 70-80% |
Long-Term Outcomes
Brostrom-Gould has excellent long-term outcomes with 20+ year follow-up studies showing maintained stability. Anatomic reconstruction approaches similar outcomes when properly indicated. Key to success: appropriate patient selection, address associated pathology, comprehensive rehabilitation.
Controversies and Areas of Uncertainty
High-level evidence in chronic ankle instability is limited, and several questions remain genuinely unsettled - examiners reward a balanced, evidence-aware answer here.
Arthroscopic vs open Brostrom
Arthroscopic and arthroscopic-assisted repair are rising rapidly. Meta-analysis shows equivalent early functional outcomes to open repair, but long-term durability data are immature and nerve-related complications (superficial peroneal, sural) are a concern. Open remains the reference standard.
Repair vs reconstruction threshold
When to abandon anatomic repair for graft reconstruction is not standardised. Proposed but unvalidated triggers: generalized hyperlaxity (Beighton high), poor remnant tissue, BMI/high demand, and revision. Some advocate primary suture-tape augmentation to allow accelerated rehab - long-term superiority is unproven.
Suture-tape (InternalBrace) augmentation
Augmenting the Brostrom with non-absorbable tape may permit earlier loading and protect the repair, but risks over-constraint, stiffness and a foreign-body construct. Evidence is mostly short-term cohort data without proven outcome benefit over standard Brostrom-Gould.
Concomitant OLT and subtalar instability
RCT data support single-stage treatment of OLT with stabilization. Subtalar instability is harder - diagnosis is unreliable (no validated stress threshold), and whether it needs specific surgical address versus a combined ATFL/CFL reconstruction remains debated.
Balanced Exam Answer
When asked "arthroscopic or open?" or "repair or reconstruct?", state that high-quality long-term comparative data are limited, give the pragmatic indication-based answer, and acknowledge that surgeon experience and tissue quality drive the decision. Avoid dogmatic claims.
Evidence Base
- In 61 patients undergoing lateral ligament reconstruction, NO ankle had isolated ligament injury. Most common associated lesions: peroneal tenosynovitis 77%, anterolateral impingement 67%, attenuated peroneal retinaculum 54%, ankle synovitis 49%, loose body 26%, peroneus brevis tear 25%, talar osteochondral lesion 23%.
- 32 ankles in young active patients (US Naval Academy) followed a mean 26.3 years. Mean ankle function 91/100; 91% rated their ankle good or excellent. Stability durable over the long term.
- Multicentre comparison (25 anatomical reconstruction vs 29 tenodesis), mean 12.3-year follow-up. Tenodesis had more positive anterior drawer, greater talar tilt and translation on stress radiographs, more medial degenerative change, and fewer excellent results. Tenodesis does NOT restore normal ligament anatomy.
- Functional treatment (tape/brace plus a supervised exercise programme) is favoured over immobilisation for acute lateral ligament rupture. Surgery is reserved for cases failing comprehensive exercise-based treatment. Bracing reduces recurrent sprains. NSAIDs may impair healing.
- 4 comparative studies (1 RCT), 207 patients. No statistically significant difference in functional outcome scores between arthroscopic and open Brostrom repair at early term; both gave favourable results, with one study showing faster return to daily activity after arthroscopy.
- RCT of 103 patients with both CLAI and osteochondral lesion of the talus. Concurrent (single-stage) microfracture plus modified Brostrom-Gould was non-inferior to staged surgery at 24 months, and gave better Karlsson-Peterson and AOFAS scores at short-term follow-up.
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
Scenario 1: Young Athlete with Recurrent Sprains
"A 22-year-old soccer player presents with recurrent ankle sprains over 2 years. He has completed 6 months of physiotherapy with bracing. Examination shows positive anterior drawer (12mm vs 6mm contralateral). He wants to return to competitive sport."
Scenario 2: Failed Previous Repair
"A 35-year-old woman had a Brostrom repair 3 years ago that failed after 18 months. She now has persistent instability, giving way episodes, and anterior drawer 14mm (vs 5mm contralateral). MRI shows attenuated ligament remnants."
Scenario 3: Instability with OLT
"A 28-year-old basketball player has CAI confirmed on stress XR. MRI also shows a 1.2cm medial talar dome osteochondral lesion with overlying cartilage damage. He has failed conservative treatment."
Scenario 4: Functional vs Mechanical Instability
"A 30-year-old recreational runner has recurrent giving way and ankle sprains. She has completed 3 months of physiotherapy. Examination shows negative anterior drawer and talar tilt. She has significant peroneal weakness and poor single-leg balance."
MCQ Practice Points
Primary Restraint
Q: Which ligament is the primary restraint against anterior translation of the talus in plantarflexion? A: Anterior talofibular ligament (ATFL) - The ATFL is taut in plantarflexion and provides 100% of resistance to anterior talar translation at 15 degrees plantarflexion. It is the weakest and most commonly injured lateral ligament.
CFL Unique Property
Q: What unique anatomical feature of the CFL makes it important for subtalar stability? A: CFL is extra-articular and crosses the subtalar joint - Unlike the ATFL which is intra-articular, the CFL crosses both the ankle and subtalar joints, contributing to stability of both articulations.
Stress Test Thresholds
Q: What is considered a positive anterior drawer stress test in chronic ankle instability? A: Greater than 10mm absolute OR greater than 3mm asymmetry compared to contralateral - Side-to-side comparison is more reliable than absolute values due to individual variation in ligamentous laxity.
Surgical Procedure
Q: What is the gold standard first-line surgical procedure for chronic ankle instability? A: Modified Brostrom-Gould - This anatomic repair involves ATFL imbrication to the fibula with suture anchors plus reinforcement with the inferior extensor retinaculum (Gould modification), achieving 85-95% success rates.
IER Augmentation
Q: What is the purpose of the Gould modification in the Brostrom procedure? A: Reinforcement with inferior extensor retinaculum (IER) - The IER is advanced over the ATFL repair and secured to the fibula, providing additional anterior restraint and improving outcomes compared to ATFL repair alone.
Guidelines, Registries & Global Practice
Global Epidemiology
Lateral ankle sprain is one of the most common musculoskeletal injuries worldwide, with an estimated incidence around 2-7 per 1000 person-years in the general population and far higher in court and field sports (basketball, volleyball, football/soccer, netball, rugby). Roughly 20-40% of sprains lead to chronic ankle instability. The injury affects all regions and resource settings; the burden is concentrated in young, active populations, and women have a higher rate in indoor court sports.
Side-by-Side Guideline Comparison
Major Society Positions on Lateral Ankle Instability
| Body / Guideline | Initial Management | Imaging Stance | Surgical Position |
|---|---|---|---|
| Dutch / IOC evidence-based guideline (Vuurberg 2018, BJSM) | Functional treatment: brace/tape PLUS supervised exercise; avoid prolonged immobilisation | Delayed exam at 4-5 days most reliable; imaging for refractory/atypical cases | Reserve surgery for failure of comprehensive exercise-based rehab |
| AAOS / AOFAS (US practice) | Functional rehab and neuromuscular training first-line | Stress radiographs and MRI to confirm mechanical laxity and associated lesions before surgery | Anatomic repair (modified Brostrom-Gould) as standard; reconstruction for revision/poor tissue |
| BOA / UK practice (BMJ/NICE-aligned) | PRICE/POLICE then exercise rehab; brace for recurrent sprains | Selective imaging; MRI when associated pathology suspected | Surgery for documented mechanical instability failing rehab |
| ESSKA-AFAS consensus | Conservative rehabilitation first | Stress imaging and MRI for surgical planning | Anatomic repair preferred; arthroscopic management of intra-articular lesions encouraged |
Where Guidelines Agree
Across societies the message is consistent: structured exercise-based rehabilitation first, anatomic (Brostrom-type) repair as the surgical default, and reconstruction reserved for revision, hyperlaxity or poor tissue. Differences are mainly in imaging thresholds and how aggressively associated lesions are sought.
Registry & Outcome Data
- No dedicated international ligament-repair registry exists (unlike arthroplasty); evidence comes from cohort series, RCTs and meta-analyses
- Patient-reported outcome measures used: Karlsson-Peterson, AOFAS, FAAM, CAIT (Cumberland Ankle Instability Tool) for case identification
- Reported recurrence after modern anatomic repair is roughly 5-15%
High- vs Limited-Resource Practice
- High-resource: stress imaging, MRI, arthroscopy, suture-anchor/graft constructs, supervised return-to-sport programmes
- Limited-resource: clinical diagnosis and functional rehab predominate; bracing/taping widely used; non-anatomic tenodesis may still be performed where anchors/grafts are unavailable
- Functional rehabilitation is effective and low-cost - the global first-line everywhere
Global Exam Focus
Examiners worldwide (FRCS, FRACS, EBOT, ABOS, DNB/MS, MRCS, SICOT) expect: mechanical vs functional instability, anatomy of the lateral ligament complex (ATFL taut in plantarflexion, CFL extra-articular crossing the subtalar joint), stress radiograph thresholds, the Brostrom-Gould technique, and indications for graft reconstruction in revision/hyperlaxity settings.
CHRONIC ANKLE INSTABILITY
Clinical summary
Key Anatomy
- •ATFL: weakest ligament, intra-articular, taut in PLANTARFLEXION
- •CFL: EXTRA-ARTICULAR, crosses subtalar joint, taut in DF
- •PTFL: strongest, rarely injured
- •Anterior drawer tests ATFL; Talar tilt tests CFL
Instability Types
- •MECHANICAL: true laxity (positive stress tests/XR)
- •FUNCTIONAL: giving way WITHOUT laxity (proprioceptive deficit)
- •Most CAI patients have BOTH components
- •Surgery for mechanical; Rehab for functional
Stress Test Thresholds
- •Anterior drawer: greater than 10mm OR greater than 3mm asymmetry = positive
- •Talar tilt: greater than 10 degrees OR greater than 5 degrees asymmetry = ATFL + CFL
- •Always COMPARE to contralateral side
- •Asymmetry more reliable than absolute values
Surgical Approach
- •Brostrom-Gould = GOLD STANDARD (85-95% success)
- •Gould modification = IER reinforcement (critical)
- •Graft reconstruction for: revision, hyperlaxity, poor tissue
- •Non-anatomic tenodesis largely HISTORICAL
Exam Pearls
- •6 months conservative before surgery
- •ATFL provides 100% resistance to anterior translation at 15 degrees PF
- •Always assess for OLT (15-25%), peroneals, subtalar instability
- •Cavovarus = higher recurrence - consider calcaneal osteotomy