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

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


Kerley lines - types

Kerley lines are named after Peter J. Kerley, a British radiologist, who identified types of septal lines on chest radiographs in patients with congestive heart failure.

Type Description
Kerley A lines linear opacities usually 2 - 6 cm long radiating from the hila into the periphery, caused by distention of lymphatic channels between perivenous and peribronchovascular lymphatics
Kerley B lines

Shoulder impingement syndrome - Neer classification

Neer classification divides lesions of the rotator cuff into three stages that typically succeed in this order during one's life.

Stage Description Age group
Stage I actue inflammation, edema, hemorrhage in the rotator cuff younger patients <25 years
Stage II progression to fibrosis and tendinitis of the rotator cuff usually between 25 and 40 years
Stage III

Grades of osteoarthritis by Ahlbäck

Grading of joint osteoarthritis by Ahlbäck uses plain postero-anterior weight-bearing radiographs to assess the extent of degenerative disease as joint space narrowing and bone attrition.

Grade - Changes Description
Grade I joint space narrowing (<3mm)
Grade II joint space obliteration
Grade III minor bone attrition (0 - 5mm)
Grade IV
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