Definition
Chronic instability due to rupture of one or more parts of the lateral ligament
Anatomy
Progressive injury
1. Anterolateral capsule
2. ATFL
3. CFL
NHx
Can lead to ankle OA over time
History
Swelling over anterolateral ankle
Giving way with inversion
- occurs with activity & walking on uneven ground
- stiffness, locking, crepitation
Chronic pain is unusual with isolated chronic instability
Examination
Tender & swelling over involved ligaments
- anterior to lateral malleolus for ATFL
- inferior to lateral malleolus for CFL
Limited dorsiflexion
Calf atrophy (especially peroneal)
Instability
- depends on ligaments involved
ATFL Instability
1. Positive Anterior Drawer
- anterior subluxation on anterior drawer of talus on tibia
- ankle in 10° PF
2. Increased inversion on varus stress with AJ in PF
CFL Instability
1. Increased inversion on varus stress with AJ in DF
2. Positive Talar Tilt
ATFL & CFL instability
1. Increased inversion on varus stress in all positions of AJ
2. Positive Anterior Drawer and Talar Tilt
Stress Xrays
Plain xray usually normal
- look for OCD
- medial aspect of talus
1. Talar Tilt
Best to supervise personally, use lead gloves
- mortise view
- AJ 10o PF
- > 10° side to side difference
2. Anterior Drawer
AJ 10° PF knee flexed
- side to side diff 3mm
- > 10mm on single film
MRI
Will demonstrate tears of ATFL / CFL
DDx
Bone
- tibiofibular synostosis
- stress fractures (calcaneum)
- intra-articular fracture / OCD
- lateral talar process
Ligament
- syndesmosis strain
Tendon
- peroneal tendonitis / subluxation / dislocation
Nerve / RSD
Sinus tarsi syndrome
- pain & tenderness over lateral opening sinus tarsi
- inversion injury
- tear of interosseous talocalcaneal ligament
- usually heals but can get synovitis
Mechanical Instability vs Functional Instability
Mechanical
- beyond physiologic range
- >10mm anterior drawer / >10° talar tilt
Functional
- ankle giving way during ADL's
Classification O'Donoghue
Grade 1
Partial Tear ATFL or CFL
- incomplete injury
- negative Anterior Draw clinically and on xray
- negative Talar Tilt clinically and on xray
Grade 2
Torn ATFL +/- partial CFL
- positive Anterior Draw clinically and on xray
- negative Talar Tilt clinically and on xray
Grade 3
Torn ATFL & CFL
- positive Anterior Draw clinically and on xray
- positive Talar Tilt clinically and on xray
Management
Non-operative (90%)
Rehabilitation programme
- strengthen of peronei
- proprioception (wobble board)
Shoe-wear modification with lateral flared heel
Operative Management
Indication
Instability with failure of non-operative treatment
Patient not willing to accept the discomfort
Options
1. Anatomic repair / modified brostrom
2. Advancement
3. Augmentation of repairs
1. Anatomic Repair / Modified Brostrom
Procedure
- mid substance repair
- often attenuated
Advantages
- restore normal anatomy & mechanics
- no donor site morbidity or weakening
Gould Modification
Technique
- suturing extensor retinaculum over ATFL repair
Advantages of modification
- reinforces repair
- limits inversion
- correct STJ part of instability (present in 10%)
Inferior extensor retinaculum anatomy
- laterally arises from anterior surface calcaneum
- medially has 2 limbs - med malleolus & plantar aponeurosis
Results
85% G/E without Gould modification
95% G/E with Gould modification
Poor outcome
1. Generalised ligamentous laxity
2. >10 yrs instability
3. Previous operations
4. Ankle osteoarthrosis
2. Fibular advancement of ATFL / CFL
Technique
EUA
- confirm talar tilt / anterior draw
Longitudinal incision anterior to lateral malleolus
- protect branches of SPN
- expose tissue of ATFL / CFL
- can often feel them
- tissue is broad and diffuse
Dissect out two flaps
- anterior incision between ATFL and CFL to talus
- begins at tip of fibula to talus
- superior flap is ATFL
- take off fibula as broad / thick flap
- inferior flap is CFL
- need to protect peroneals with inferior portion of dissection
Inspect talar dome for OCD
- place retractor across talar dome
- ensure no loose bodies
- can remove anterior ankle osteophyte if necessary
Place foot in eversion and AJ neutral
2 x 3.5 mm anchors in fibula
- ensure not in joint and not prominent
- 4 sutures through ATFL
- 2 through CFL
- 2 sutures either side of interval of ATFL and CFL so can close this
Make sure FROM & anterior drawer is negative at end
Extensor retinaculum is sutured over the site
- over ATFL
- over anterior aspect of fibula
Post op
- weight bear in moon boot for 6/52
- sport 3/12
3. Augmented Repairs
Technique
- most use peroneus brevis (PB)
Indications
- poor tissue for anatomic repair
- long standing instability
- hypermobile STJ / ligamentous laxity
- previous surgery / revision
A. Chrisman & Snook
Reconstructs ATFL + CFL
- stabilizes the STJ
- preserves 1/2 PB
- most widely used non-anatomic reconstruction
Good results in 90%
- restricted inversion (100%) and dorsiflexion (20%)
Technique
- split PB in 2 leaving 1/2 attached to 5th MT base
- drill fibula transversely in AP direction
- drill calcaneus with small tunnel inferior to fibula
- thread tendon from fibula anterior to posterior & then into calcaneus
- then back onto PB / PL or to PB anterior to fibula
B. Evans
Tenodesis of PB
- divide proximally
- re-route through drill hole from anteroinferior tip to postero-superior
- pass PB through & suture to proximal end
- will also limit SJ motion
Baltopoulis et al. CORR 2004
- 27 patients, average AOFAS score 91
- 1/3 restricted hindfoot movement
C. Watson-Jones
Attempt to recreate ATFL with PB tenodesis
- detach PB tendon as proximally as possible
- drill hole through fibula transversely 1 inch from tip
- drill second hole through talar neck
- thread tendon through fibular posterior to anterior
- then through talus superior to inferior
- suture back to itself over LM
- limits STJ motion
D. Colville
Anatomic reconstruction CFL and ATFL
- 1/2 PB left attached distally
- through calcaneal tunnel
- to tip fibula tunnel to anterior fibula 8mm proximally
- to talar neck tunnel and back to anterior tibia
- idea is not to restrict STJ movement