A comminuted fracture is also known as a multifragmentary fracture and is characterized by the bone being broken into more than two pieces. There are several sub-types of 'comminuted fracture' or 'multifragmentary fracture' that describe specific forms of these fractures in more detail, such as:

Spiral wedge fracture - due to torsional force(s)
Bending wedge fracture - usually due to direct or indirect violence
Complex spiral fracture - has more than one spiral element
Complex segmental fracture - has one or more distinct 'complete' sections of bone, as opposed to multiple small irregular fragments
Complex irregular fracture - the bone between the main (largest) sections is broken into many irregular pieces or fragments, some of which may be very small. - http://www.ivyroses.com/HumanBody/Skeletal/Fractures/Types-o...

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Complex Fractures
About Complex Fractures

The term “complex fracture” describes a broken bone that is more severe than what is common or routine. Fractures are considered to be complex when:

The fragments are comminuted (broken into many pieces)
The soft tissues are severely damaged
There is loss of bone due to severe trauma
There is disruption of the articular surface (severe cartilage injury at a joint)
There are multiple fractures at several levels in a single bone
There is an associated joint dislocation - http://drbrinker.com/complex-fractures/

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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1399838/pdf/ann...

https://books.google.com/books?id=D94WAAAAYAAJ&pg=PA445&lpg=...

Fracture patterns and their significance

1. Hairline fracture

2. Greenstick fractures

3. Simple fractures

4. Multifragmentary (comminuted) fractures

5. Multifragmentary complex fractures

Pocketbook of Orthopaedics and Fractures - https://goo.gl/BdKMCP - pages 212, 213