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Pauwels Calculator
Pauwels Classification of Femoral Neck Fractures
The Pauwels classification grades an intracapsular femoral neck fracture by the angle between the fracture line and the horizontal plane on an anteroposterior radiograph — type I below 30°, type II from 30° to 50°, and type III above 50° — because the more vertical the fracture, the greater the shear component across it and the higher the risk of fixation failure.
What the Pauwels score means
Pauwels scores run from 0 to 90, where a lower score is better. The bands below are conventional reporting categories, not diagnostic cut-offs.
- Pauwels I — fracture line under 30° from the horizontal0–29.9
The fracture plane is close to horizontal, so body weight crossing the neck is resolved mainly into compression across the fracture. The most mechanically stable pattern and the one with the lowest reported rate of fixation failure.
- Pauwels II — fracture line 30° to 50° from the horizontal30–50
An intermediate obliquity in which compressive and shear components across the fracture are of comparable magnitude.
- Pauwels III — fracture line above 50° from the horizontal50.1–90
A near-vertical fracture plane, in which shear predominates over compression. Conventionally regarded as the least stable pattern and the one most likely to fail simple screw fixation; a fixed-angle device or an added anti-glide construct is commonly used.
Published criteria and reliability
The published cut-offs that define this instrument, and the measured agreement between observers using it. Each is reported with the population it was derived in.
| Type | Value | Subscale | Population | Follow-up | Source |
|---|---|---|---|---|---|
| Criterion | Under 30° — type I (conventional cut-off; not fixed numerically by Pauwels) | — | Intracapsular femoral neck fracture, anteroposterior radiograph | — | Shen M 2016 |
| Criterion | 30° to 50° — type II (conventional cut-off; not fixed numerically by Pauwels) | — | Intracapsular femoral neck fracture, anteroposterior radiograph | — | Shen M 2016 |
| Criterion | Above 50° — type III (conventional cut-off; not fixed numerically by Pauwels) | — | Intracapsular femoral neck fracture, anteroposterior radiograph | — | Shen M 2016 |
| Criterion | Interobserver agreement kappa 0.31; the authors concluded the classification is unreliable and that its use should be avoided | — | Ten observers classifying 100 intracapsular femoral neck fractures | — | van Embden D 2011 |
Criterion is a published cut-off, definition or performance figure belonging to a classification or decision rule — it is not a change score and should not be read as one.
How the score is calculated
Stated in full so the calculation can be independently checked, and reproduced by hand if needed.
Draw a line along the fracture as it appears on the anteroposterior radiograph, then draw a horizontal line — one parallel to the inter-teardrop line and therefore perpendicular to the long axis of the body. The Pauwels angle is the angle between those two lines. An angle of less than 30° is type I, an angle from 30° to 50° inclusive is type II, and an angle greater than 50° is type III. Those numbers are the modern convention rather than a quotation from Pauwels: his 1935 monograph did not set fixed critical angles, and defined the grades by the mechanical behaviour of the fracture — whether the shear across it can be neutralised by impaction, and whether a free torque distracts the proximal fragment. Bartoníček’s re-reading of the original makes the point that textbook versions of the angles differ from one another for exactly this reason, and other cut-offs (most often 30°/70°) are still in circulation. The 30°/50° form is used here because it is the form in which the classification is now applied and reported; record the measured angle itself alongside the type so the reader is not dependent on which convention you used. The mechanical reasoning behind the cut-offs is that the resultant force crossing the femoral neck can be resolved into a component compressing the fracture and a component shearing it; as the fracture plane becomes more vertical, the shear component grows and the compressive component shrinks, so a type III fracture is loaded in a way that tends to displace it rather than impact it.
Missing data
The classification requires the angle. If the angle is blank, out of the 0–90° range, or not a number, no type is reported and the result explains what is needed instead.
Instrument profile
- Developer
- Friedrich Pauwels
- Institution
- RWTH Aachen, Germany
- First published
- 1935
- Items
- 1
- Response format
- One angular measurement in degrees
- Score range
- 0 to 90
- Direction
- Lower score = better
- Completion time
- About 1 minutes
- Age range
- Adults; most often applied to the vertical fractures seen in younger, higher-energy injuries
- Regions
- Hip
- Conditions
- Femoral neck fracture, Intracapsular hip fracture, Vertical femoral neck fracture
- Procedures
- Cannulated screw fixation, Sliding hip screw, Fixed-angle plate fixation, Femoral neck system fixation
- Validity
- The mechanical rationale — shear rising with the obliquity of the fracture plane — is sound and is supported by biomechanical testing. The clinical association between Pauwels type and non-union or fixation failure is the conventional teaching but has not been reproduced consistently in retrospective clinical series, partly because the angle itself is measured unreliably.
- Reliability
- Reliability is the system’s weak point. The measured angle varies with limb rotation and with pre- versus post-reduction imaging. In the largest reliability study — ten observers, 100 fractures — interobserver agreement was kappa 0.31, and the authors concluded that classification by the Pauwels angle is unreliable and should be avoided. Report the measured angle rather than the type alone.
When to use the Pauwels
Well suited to
- Describing the obliquity of a vertical femoral neck fracture in a younger patient, where the choice between cannulated screws, a sliding hip screw and a fixed-angle construct turns on shear.
- Communicating fracture geometry in an operative plan or a research dataset, alongside the Garden grade rather than instead of it.
Limitations and poor fits
- Extracapsular fractures — intertrochanteric, basicervical and subtrochanteric patterns are outside the system.
- As a stand-alone reliability-dependent research variable, given the documented interobserver disagreement; report the measured angle itself rather than only the type.
- On a rotated or poorly positioned film, where the projected fracture line does not represent its true plane.
- In isolation for treatment decisions: patient age, bone quality, displacement (Garden grade), comminution and the quality of reduction all matter at least as much.
Pauwels compared with other instruments
Instruments measuring a related construct, with the practical difference between them.
| Instrument | Items | Range | What it adds |
|---|---|---|---|
| Garden | 2 | 1–4 | The Garden classification grades intracapsular femoral neck fractures into four types by the completeness of the fracture line and the degree of displacement on an anteroposterior radiograph, where types I and II are non-displaced and types III and IV are displaced. |
| AO/OTA | 3 | 1–3 | The AO/OTA classification gives every fracture an alphanumeric code in which the first digit is the bone, the second the segment and the letter the fracture type — extra-articular, partial articular or complete articular in an end segment, and simple, wedge or multifragmentary in a shaft — so that 32-A is a simple femoral shaft fracture and 43-C a complete articular pilon fracture. |
| Harris Hip Score | — | 0–100 | The Harris Hip Score is a 100-point clinician-administered hip assessment combining 44 points for pain, 47 for function, 4 for absence of deformity and 5 for range of motion, where 90 or above is graded excellent and below 70 poor. |
Copyright and permitted use
Published openly because it is the question every clinician and researcher asks before using an instrument, and almost nobody answers it.
A published radiographic measurement and classification method, not a questionnaire. The angle and its thresholds are freely reproducible and no licence is required.
References
- Pauwels F. Der Schenkelhalsbruch: ein mechanisches Problem. Ferdinand Enke Verlag, Stuttgart (monograph). 1935.
- Bartoníček J. Pauwels’ classification of femoral neck fractures: correct interpretation of the original. Journal of Orthopaedic Trauma. 2001.
- van Embden D, Roukema GR, Rhemrev SJ, Genelin F, Meylaerts SAG. The Pauwels classification for intracapsular hip fractures: is it reliable?. Injury. 2011.
- Shen M, Wang C, Chen H, Rui YF, Zhao S. An update on the Pauwels classification. Journal of Orthopaedic Surgery and Research. 2016.
Editorial status
This page has not yet been signed off by a named clinical reviewer. The scoring logic is stated in full above so it can be independently verified, and every threshold is traceable to its source. See our editorial methodology.