Schatzker Classification Explained Type by Type, With CT Signs and Fixation Strategy

A tibial plateau fracture gets a Schatzker number on every trauma list, and the number is meant to carry the energy of the injury and the operation it needs. The Schatzker classification does that well for the lateral plateau and for the line between one condyle and two. It is drawn on the AP radiograph, though, and it does not describe the posterior fragments that most often decide the approach. The answer in one sentence: use Schatzker for the pattern and the energy, then plan the incisions from the CT, column by column. The full clinical picture is on the tibial plateau fractures topic page.

What are the six Schatzker types?

Schatzker, McBroom and Bruce published the system in 1979 from the Toronto experience of 1968–1975. It describes six patterns on plain radiographs, and the number broadly tracks energy: types I–III are lower-energy injuries of the lateral plateau, types IV–VI the medial, bicondylar and dissociated patterns of higher-energy trauma. The lateral plateau is involved in 55–70% of plateau fractures, and type II is the most common type.

Two boundaries carry most of the weight. Between III and IV the injury moves from the lateral plateau to the medial, which is treated as high-energy until proven otherwise. Between IV and V it moves from one condyle to two, and with it from a single approach to staged surgery and two plates. In AO/OTA terms the bicondylar fractures are complete articular, segment 41-C; the AO/OTA classification page sets out the lettering.

Types I to III: the lateral plateau

The lateral plateau is convex, sits about 3 mm higher than the medial and is the side prone to depression. Three patterns follow from that.

Type I: the pure split. A wedge of lateral condyle is split off by a low-energy valgus force, with no articular depression, in younger and denser bone. Fixation is often percutaneous lag screws, with or without a lateral buttress plate. Plain films underestimate depression, so the CT is there to confirm that no depressed segment is hiding behind the split, and to size the fragment for the screws.

Type II: split-depression. The most common type and the common operative pattern: a lateral split with a depressed articular segment beside it. Through an anterolateral approach with a submeniscal arthrotomy, the split fragment is opened like a book to expose the depression, which is lifted with a tamp. The metaphyseal void is filled, raft screws go immediately beneath the subchondral bone, the split is closed over the restored joint surface, and a lateral buttress or locking plate holds it. Calcium phosphate cement has the higher compressive strength and lower rates of subsidence than calcium sulfate, which is why it is the favoured filler under a reduced surface.

The meniscus is part of the type II injury. Gardner and colleagues obtained pre-operative MRI in 62 consecutive Schatzker II fractures. With depression over 6 mm and condylar widening over 5 mm on the AP radiograph, lateral meniscal injury was present in 83%, against 50% with less displacement. Lateral collateral and posterior cruciate ligament tears were not seen below 4 mm of displacement but approached 30% as it increased. The lateral meniscus can also be trapped in the fracture; tears are addressed at the time of fixation.

Type III: pure depression. A central depression with the lateral cortex intact, usually a low-energy axial injury in osteoporotic bone. With no split to open, the depressed segment is reached through a metaphyseal cortical window, lifted, and supported with raft screws and a void filler. Arthroscopic-assisted reduction suits types I–III: it shows the step-off directly and lets meniscal and chondral injury be treated. The trap is irrigation fluid leaking through the fracture into the leg compartments, so inflow pressure is kept low and the calf watched.

II or III? The difference is the cortical break. If the cortex is split, the split is the door to the depression; if it is intact, the surgeon has to make a window. Because the choice of exposure turns on it, it is worth confirming on the CT rather than the AP film.

Why is a Schatzker IV fracture different?

The medial plateau is concave, congruent, has the stronger subchondral bone and takes about 60% of the load in neutral alignment. Breaking it usually takes a high-energy varus force. The tibial plateau ORIF operative guide treats a medial plateau fracture as a knee-dislocation-equivalent, with the highest risk of popliteal arterial injury, common peroneal nerve palsy and compartment syndrome of the six types. In one series of 67 knees in spanning frames, compartment syndrome followed 9 of 17 (53%) medial plateau fracture-dislocations against 9 of 50 (18%) type VI fractures (Stark 2009 (opens in a new tab)).

The limb before the bone. Document foot pulses, the ankle-brachial pressure index, common peroneal nerve function and all four compartments before discussing fixation. Any abnormal pulse, or an ABPI under 0.9, means CT angiography and vascular review. When the plateau fracture comes with a knee dislocation, Moore's classification is the one used; the vascular pathway is on the knee dislocation page and fasciotomy on the compartment syndrome of the leg page.

The fixation follows the fragment. A medial fragment that is a posteromedial coronal split displaces posteriorly under axial load, so it needs a buttress plate on the posterior surface; an anteromedial approach cannot place a true posterior buttress. That is the job of the posteromedial approach to the tibial plateau: prone, knee flexed 20–30°, through the interval between the pes anserinus and the medial head of gastrocnemius, with the saphenous nerve found and protected early. High-energy type IV injuries are staged like V and VI when the soft tissues demand it, and types IV–VI stay non-weight-bearing for at least 6–8 weeks.

Types V and VI: bicondylar fractures and staged surgery

Type V splits both condyles, classically as an inverted Y, with the metaphysis still in continuity with the shaft. Type VI adds a fracture that dissociates the metaphysis from the diaphysis. Both are high-energy, and in both the soft tissues set the timing.

Stage the knee. A knee-spanning external fixator goes on the day of injury. The leg is kept raised, the wrinkle test is repeated, and definitive fixation follows at about 7–21 days, once the skin wrinkles and blisters have epithelialised. Both blister types are a split at the dermo-epidermal junction, but under a blood-filled blister the dermis is stripped completely of epidermis, a slightly deeper injury in which incisions heal less well, so incisions are kept away from haemorrhagic blisters (Giordano 1994 (opens in a new tab)). In Egol's prospective protocol of 57 high-energy fractures, 74% of them Schatzker VI, deep infection was 5% overall (PubMed 16056075 (opens in a new tab)). The wider logic is in our post on damage control orthopaedics, and the compartment that can turn up after fixation in our compartment syndrome diagnosis and fasciotomy post.

Two incisions, two plates. The standard is an anterolateral approach for the lateral column and a posteromedial approach for the medial, with a skin bridge of over 7 cm. A single lateral plate leaves the medial column unsupported, and it collapses into varus. Barei and colleagues treated 83 AO/OTA 41-C3 fractures with medial and lateral plates through two exposures. Of the 31 patients with complete radiographs, only 55% had a satisfactory articular reduction (step or gap of 2 mm or less), and after adjusting for age and polytrauma a satisfactory reduction was associated with better function. Residual dysfunction was common.

Or a ring. The Canadian Orthopaedic Trauma Society randomised 83 Schatzker V–VI fractures to dual plating or to limited fixation with a circular fixator. Reduction quality was similar and two-year WOMAC scores did not differ. Plating had more blood loss (544 vs 213 mL), a longer stay (23.4 vs 9.9 days), deep infection in 7 of 40 (18%), and more unplanned reoperations (37 procedures against 16). Periarticular wires are kept roughly 14 mm or more below the joint line to stay extracapsular; frame principles are on the Ilizarov external fixation page.

What does CT add to a Schatzker type?

Less to the label than to the plan. Yacoubian and colleagues had three trauma surgeons read radiographs alone, with CT and with MRI, blinded. Adding CT changed the Schatzker type in only 6% of cases and moved interobserver kappa from 0.68 to 0.73. In an earlier series using the AO system, plain films underestimated 18 of 42 fractures, and CT changed the surgical plan in 13 of 22 (Wicky 2000 (opens in a new tab)). Different studies, different systems, but the direction is consistent: the scan changes the operation more often than the number.

What to read on the CT:

• Depression depth and area, which decide elevation and the volume of void filler
• Coronal-plane fracture lines, above all a posteromedial or posterolateral fragment, which decide the approach
• Fragment size, which decides whether screws will hold
• Comminution, which decides between spanning and length-stable fixation
• The lateral cortex, which separates a type II from a type III

Timing matters too. In a high-energy plateau the CT is best taken after the spanning frame, when ligamentotaxis has pulled the fragments towards the shape you will operate on; a scan of the grossly displaced knee overstates the comminution. The physics and protocols are on the CT imaging principles page.

Where does the Schatzker classification fall short?

Kfuri and Schatzker put it plainly when they revisited the system in 2018: it is a two-dimensional representation of the fracture. The AP film shows which condyle is broken but not whether the main fracture plane runs anterior or posterior, and the posterior fragments are where the fixation fails.

The posteromedial fragment. Higgins and colleagues reviewed CT in 111 bicondylar fractures and found a posteromedial fragment in 65 (59%). It averaged 25% of the joint surface, had over 5 mm of articular displacement in 55%, and ran nearly vertically (mean sagittal angle 73°), the shape of a shear fragment. Barei's group found it in 42 of 57 bicondylar fractures that involved the medial articular surface, nearly a third of the bicondylar fractures they evaluated. In a composite-bone model, every construct failed at the posteromedial fragment first, and the authors suggested lateral locking screws may not reliably reach it (Yoo 2010 (opens in a new tab)).

The three-column concept. Luo and colleagues divided the plateau on axial CT into lateral, medial and posterior columns. A column is involved when it holds a separate articular fragment, and each involved column gets its own approach and fixation. In their 29 three-column (Schatzker V–VI) fractures, fixed through a posterior inverted-L approach combined with an anterolateral one, all but one had a satisfactory reduction and none showed secondary articular depression, in a single-centre cohort without a comparison group.

Schatzker's own revision. Kfuri and Schatzker kept the six types but added a coronal "equator" that splits each condyle into anterior and posterior quadrants. Types I–IV take an A or P modifier for the location of the main fracture plane, and V–VI take one for each column. The point is the same as Luo's: positioning, approach and plate position follow the main fracture plane, which only CT shows.

How reliable is the Schatzker classification?

Usually only moderately on plain films.

• Walton (2003): three observers, 30 fractures; Schatzker interobserver agreement was only fair, and AO was more reliable between observers (PubMed 14574596 (opens in a new tab)).
• Charalambous (2007): six observers, 50 fractures, AP and lateral films; interobserver kappa 0.41 for Schatzker and 0.43 for AO/OTA. Grouping fractures as unicondylar or bicondylar, and as pure split or depression with or without split, improved agreement.
• Maripuri (2008): four observers, 50 fractures; Schatzker interobserver kappa 0.47 and intraobserver 0.91, better than AO (0.36) and Hohl and Moore (0.14).
• Brunner (2010): four observers, 45 fractures; adding CT improved interobserver reliability from moderate to good for Schatzker, AO/OTA and Hohl alike (PubMed 19744652 (opens in a new tab)).
• Millar (2018), systematic review: plain-film reliability was frequently moderate (kappa 0.40–0.60), CT typically improved it, and the simpler three-column system scored higher (interobserver kappa 0.71–0.87) at the cost of less detail on morphology.

The practical reading matches what Charalambous found. Observers agree on the large decisions, one condyle or two, split or depression, and disagree on the finer boundaries. Say what you see in those terms, then give the number.

In the exam

Examiners want the type named, the energy recognised, the CT used for the right reason and the limits of the system acknowledged. For holding six types and their consequences in memory, see how to memorise orthopaedic classifications.