Freiberg disease

Freiberg disease, also known as Freiberg infraction, is osteochondrosis of metatarsal heads. It typically affects the 2^nd metatarsal head (the 3^rd and  4^th may also be affected). It can be bilateral in up to 10% of cases.

Epidemiology

It is commoner in women aged 10-18 (male to female ratio of 1:3). 

Clinical presentation

Clinically they present with pain that is increased by weight-bearing, plus swelling and tenderness.

Pathology

The cause of Freiberg infraction is controversial and is probably multifactorial.

A traumatic insult in the form of either acute or repetitive injury and vascular compromise, perhaps due to an elongated 2^nd metatarsal, are the most popular theories, and as it is more commonly seen in women, particularly during adolescence, high-heeled shoes have been postulated as a possible causative factor.

Histologically, Freiberg infraction is characterised by the collapse of the subchondral bone, osteonecrosis, and cartilaginous fissures ¹. 

Radiographic features

Plain radiograph

These can be split into early and late features:

Early

• flattening and cystic lesions of the affected metatarsal head
• widening of the metatarsophalangeal (MTP) joint

Late

• osteochondral fragments
• sclerosis and flattening of the bone
• increased cortical thickening

Some publications advocate use of the Bragard staging classification ¹⁰, which requires 2 views/planes of the forefoot:

• I - metatarsal head flattening and decreased subchondral bone density
• II - metatarsal head sclerosis, fragmentation and deformation, with cortical thickening
• III - metatarsophalangeal (MTP) osteoarthrosis with intra-articular loose bodies

MRI

Early MR imaging findings include low-signal-intensity changes in the metatarsal head on T1-weighted images with increased signal intensity on corresponding T2-weighted and STIR images.

With disease progression, flattening of the metatarsal head occurs, and low-signal-intensity changes develop on T2-weighted images as the bone becomes sclerotic.

History and etymology

Albert H Freiberg first described it in 1914 ^8,9.

Differential diagnosis

On imaging consider

• normal variant, as a flat metatarsal head is described in ~10% of asymptomatic population
• fracture of metatarsal head or neck
• unstable metacarpus (only identified on MRI)
  • torn metacarpophalangeal collateral ligaments 

Practical points

• adolescent or young women
• pain and swelling at 2^nd metatarsophalangeal (MTP) joint
• flattening and cystic lesions of the affected metatarsal head
• widening of the MTP joint

See also

• avascular necrosis