Mason classification of radial head fractures

The classification of radial head fractures is based on the

  • degree of displacement
  • intra-articular involvement

as follows

  • Mason type 1 - non-displaced to minimally displaced fracture (<2mm)
  • Mason type 2 - intra-articular fracture with displacement >2 mm or angulation
  • Mason type 3 - comminuted intra-articular fracture with displacement 

Sternoclavicular joint injury - Allman classification

Posttraumatic instability of the sternoclavicular joint is a result of injury to the joint capsule, the sternoclavicular or costoclavicular ligament.

Grade Description
Grade I sprain of the sternoclaviular joint without laxity and minimum pain
Grade II rupture of the sternoclavicular ligaments without rupture of the costoclavicular ligament
Grade III

Perilunate instability - Mayfield classification of carpal instability

Mayfield et al. described in 1980 the following four stages of progressive carpal instability.

Stage Description
Stage I scapholunate dissociation: dorsal dislocation of the proximal scaphoid pole in the radiocarpal joint (rotatory subluxation of the scaphoid) with disruption of the dorsal scapholunate ligament leads to widened scapholunate distance (Terry Tomas sign) on radiograph
Stage II

Posterior dislocation of the hip - Thompson-Epstein classification

Thompson-Epstein classification describes five types of posterior hip dislocation defined by associated acetabular fracture or fracture of the femoral head as depicted on plain radiographs. In general, there are three types of dislocations in the hip joint:

  • posterior: the femoral head is dislocated posteriorly, most commont type
  • anterior: the femoral head is dislocated anteriorly
  • central: impact of the femoral through the acetabular floor into the pelvis

Dislocation in acromioclavicular joint - Rockwood classification of AC dislocation

Rockwood classification divides dislocations in AC joint into six grades. It is an extension of the previous classification by Tossy et al. Normal width of AC joint is considered 1-3mm, widened AC joint has >7mm in men or >6mm in women.

Grade Description
Grade I sprain of the acromioclavicular (AC) ligaments
Grade II complete rupture of the AC ligaments
Grade III

Dislocation in acromioclavicular joint - Tossy classification of AC dislocation

Tossy classification divides dislocations in AC joint into three grades. It was later extended by Rockwood et al. by another three types. Normal width of AC joint is considered 1-3mm, widened AC joint has >7mm in men or >6mm in women.

Grade Description
Grade I no deformity visible on x-ray - strain and contusion of the AC joint
Grade II

Lesion of labrum glenoidale - Snyder classification of labral lesions (SLAP)

The classification of lesions of labrum glenoidale was published by Snyder et al. and had originally four types. Later, several authors added descriptions of other labral lesions.

Type Description
Type I fraying
Type II tear with biceps extension
Type III bucket-handle tear with intact biceps
Type IV bucket-handle tear with biceps extension

Atlanto-occipital dislocation - types

Complete atlanto-occipital dislocation (AOD) can be divided into three distinct types.

Type Description
Type I ventral dislocation - the most common
Type II axial dislocation - the most unstable
Type III dorsal dislocation - rare


Fracture types of axis, C2 by Effendi, modified by Levine & Edwards

The classification of fractures of axis was introduced by Effendi et al. and later modified by Lewine and Edwards. With further two types added (IA and IIA), the modified classification has five types.

Type Description
Type I fracture of the pedicles, intervertebral disc C2/3 is intact, dislocation ≤3mm without angulation
Type IA fracture lines on each side are not parallel, fracture line may involve foramen transversarium on one side

Grading of meniscal injury

Lesions of the menisci on MRI are divided into four grades. Normal meniscus has uniformly low signal intensity on T2-weighted images (T2W). Grade I and II lesions can be a normal appearance of ageing in older patients.

Grade Description
Grade I small focus of increased signal intensity on T2W, that does not extend to the articular surface
Grade II linear area of increased signal intensity without extension to the articular surface
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