Orthonotes
by the.bonestories
Menu
SA (supination-adduction): lat avulsion → vertical medial fx. SER (supination-external rotation): ATFL → fibula at level → posterior → medial (most common). PA (pronation-abduction), PER (pronation-external rotation) sequences predict associated injuries.
10 AI-generated high-yield questions by our AI engine
The Lauge-Hansen classification (described by Niels Lauge-Hansen in 1950 based on cadaveric experiments) is the mechanism-based classification system for ankle fractures. Unlike the Danis-Weber classification (which is purely anatomical — based only on the fibular fracture level), the Lauge-Hansen system describes the sequence of ligamentous and bony injuries that occur as the foot adopts a specific position and the deforming force is applied. This makes it invaluable for: (1) understanding the full extent of an ankle injury (including ligamentous injuries not visible on plain X-ray); (2) guiding reduction technique (reversing the mechanism); (3) predicting associated injuries beyond the obvious fractures; (4) surgical planning. It is complementary to the Danis-Weber system, not a replacement.
| Type | Stage | Injury at Each Stage | Weber Equivalent |
|---|---|---|---|
| Supination-Adduction (SA) | Stage 1 | Transverse avulsion fracture of the LATERAL MALLEOLUS at or below the joint line — the lateral collateral ligament (ATFL/CFL) avulses the tip of the fibula transversely; OR lateral ligament tear (ATFL ± CFL) without fracture | Weber A (infrasyndesmotic) |
| Stage 2 | Vertical fracture of the MEDIAL MALLEOLUS (vertical shear fracture from the adducted talus impacting the medial malleolus — the talus is driven medially and superiorly against the medial malleolus, creating a vertical `crush` fracture); this vertical medial malleolus fracture is pathognomonic of SA Stage 2 and is an important operative consideration (vertical medial malleolus fractures require lag screw fixation oblique to the fracture line, NOT the standard horizontal screw used for transverse medial malleolus fractures) | ||
| Supination-External Rotation (SER) — MOST COMMON (~60%) | Stage 1 | Disruption of the AITFL (anterior inferior tibiofibular ligament); OR Chaput-Tillaux avulsion fracture of the anterior tibial margin (where the AITFL inserts on the tibia); OR Wagstaffe-Le Fort avulsion fracture of the anterior fibular margin (where the AITFL inserts on the fibula); these are `equivalent` injuries — the AITFL either tears or avulses a bony fragment from one of its two bony attachments | Weber B (transsyndesmotic) — the fibular fracture in SER is the characteristic oblique/spiral fracture starting at the joint line anteriorly and running proximally and posteriorly |
| Stage 2 | Oblique or spiral fracture of the LATERAL MALLEOLUS at the syndesmotic level — the classic `Weber B` fibular fracture (starting at the ankle joint level anteriorly and spiralling proximally and posteriorly); this is the commonest ankle fracture in clinical practice | ||
| Stage 3 | Disruption of the PITFL (posterior inferior tibiofibular ligament); OR fracture of the POSTERIOR MALLEOLUS (the `third malleolus` — an avulsion of the PITFL from the posterior tibial plafond; also called `Volkmann`s fragment`) | ||
| Stage 4 | Fracture of the MEDIAL MALLEOLUS (transverse fracture from the talus being forced medially as it externally rotates) OR deltoid ligament tear (WITHOUT medial malleolus fracture — the `bimalleolar equivalent`); the most important stage for stability — if Stage 4 occurs, the ankle mortise is rotationally unstable | ||
| Pronation-Abduction (PA) | Stage 1 | Transverse fracture of the MEDIAL MALLEOLUS (avulsion by the deltoid ligament as the talus abducts) OR deltoid ligament tear; in pronation injuries, the MEDIAL SIDE FAILS FIRST | Weber C (suprasyndesmotic) for PA Stage 3 — comminuted fibular fracture at or just above the syndesmosis level |
| Stage 2 | Disruption of the AITFL + PITFL + interosseous ligament (syndesmotic complex rupture) | ||
| Stage 3 | Comminuted fracture of the FIBULA at or just above the level of the syndesmosis (from the abducting force on the fibula — the fibula is bent and fractures in a comminuted/bending pattern); the comminuted pattern of the fibula in PA is one distinguishing feature from the SER-type oblique fibular fracture | ||
| Pronation-External Rotation (PER) | Stage 1 | Transverse fracture of the MEDIAL MALLEOLUS OR deltoid ligament tear — medial side fails FIRST (identical to PA Stage 1) | Weber C (high) — the fibular fracture in PER is characteristically ABOVE the syndesmosis and may be very proximal (up to the fibular neck — the Maisonneuve fracture is a PER Stage 4 injury) |
| Stage 2 | Disruption of the AITFL and interosseous ligament | ||
| Stage 3 | Disruption of the PITFL (posterior inferior tibiofibular ligament) | ||
| Stage 4 | Spiral or oblique fracture of the FIBULA — at a level ABOVE the syndesmosis; the fracture travels PROXIMALLY along the interosseous membrane and fibula; the most extreme form is the Maisonneuve fracture (fibular neck fracture = PER Stage 4); the higher the fibular fracture, the more proximal the interosseous membrane tear |
| Lauge-Hansen Finding | Clinical/Radiological Significance |
|---|---|
| Posterior malleolus fracture (SER Stage 3 / PA / PER) | The posterior malleolus (Volkmann`s fragment) is the PITFL bony attachment; its fracture indicates the PITFL is disrupted; the posterior malleolus contributes to the bony articular surface of the tibia (the plafond); if >25% of the articular surface is involved → ORIF of the posterior malleolus is required (reduces the articular incongruency + restores the PITFL attachment = helps prevent syndesmotic instability); if <25% → non-operative (does not significantly compromise the articular surface) |
| Vertical medial malleolus fracture (SA Stage 2) | The vertical fracture pattern in SA is caused by the adducted talus impacting the medial malleolus from below; the fracture line is nearly vertical (not the usual transverse orientation of SER medial malleolus fractures); fixation requires screws placed OBLIQUELY to the fracture line (not horizontally as for transverse fractures); horizontal screws parallel to the fracture line in a vertical fracture would pull through |
| Medial side fails FIRST in pronation injuries (PA, PER) | In pronation injuries, the medial structures (deltoid ligament or medial malleolus) fail before the lateral structures; this means that in any ankle injury where the medial side is severely disrupted (large medial malleolus fracture or widely widened medial clear space), a pronation mechanism should be suspected; the fibular fracture in pronation injuries is typically HIGHER (above the syndesmosis) than in supination injuries (at or below the syndesmosis) |
| Lateral side fails FIRST in supination injuries (SA, SER) | In supination injuries, the lateral structures fail first (ATFL/lateral malleolus for SA; AITFL and lateral malleolus for SER); the medial side is injured only in higher-grade injuries (SA Stage 2; SER Stage 4); this is clinically relevant — a Weber B fibular fracture with medial tenderness but NO medial malleolus fracture = SER Stage 4 with deltoid tear = bimalleolar equivalent = unstable = operative |
10 AI-generated high-yield questions by our AI engine