Orthopaedic Surgery - Freiberg Disease (Freiberg Infraction)

Basics

Freiberg disease, also called Freiberg infraction, is an osteochondrosis or osteonecrotic disorder involving the metatarsal head, most commonly the second metatarsal head.

It typically presents in an adolescent, young adult, or occasionally middle-aged adult with well-localized pain at the second metatarsophalangeal (MTP) joint that worsens with activity and improves with rest.

Anatomic Distribution

The second metatarsal head is affected most frequently.

The third or other lesser metatarsal heads may occasionally be involved.

Disease may be unilateral or bilateral.

Disease Progression

The disorder progresses through a spectrum of subchondral injury, necrosis, collapse, and eventually degenerative arthritis.

Early radiographs may demonstrate subtle mottling, sclerosis, or central subchondral collapse.

Moderate disease produces flattening or collapse of the metatarsal head, often accompanied by osteophytes or loose osteochondral fragments.

Advanced disease is characterized by joint-space loss, articular destruction, and secondary MTP arthritis.

Epidemiology

Freiberg disease occurs more commonly in females than males.

The true incidence is uncertain because some cases remain asymptomatic and are discovered incidentally on radiographs.

Age

The condition is classically diagnosed during adolescence, especially between approximately 13 and 18 years of age, although symptoms may persist into adulthood or first become clinically apparent later.

Risk Factors

Important associations include running, dancing, repetitive forefoot loading, and a relatively long second metatarsal.

These factors increase mechanical stress across the affected metatarsal head.

Etiology

The exact cause is likely multifactorial.

Freiberg disease is characterized by compromise of the subchondral bone and blood supply of the metatarsal head, resulting in osteonecrosis and structural collapse.

Vascular Factors

Impaired local microcirculation has been proposed as an important contributor to the development of osteonecrosis.

Acute Trauma

A single traumatic event may damage the subchondral bone or vascular supply and initiate the disease process in some patients.

Repetitive Microtrauma

Repeated forefoot loading from running, jumping, dancing, or other high-impact activity may produce cumulative microtrauma.

Second Metatarsal Anatomy

The second metatarsal is often the longest metatarsal and is relatively rigidly fixed at its base.

These characteristics can subject the second metatarsal head to increased repetitive loading and may explain why it is affected most frequently.

Diagnosis

Signs and Symptoms

The characteristic complaint is pain localized to the second MTP joint.

Pain is aggravated by walking, running, sports, and other weight-bearing activity and generally improves with rest.

Swelling

Localized swelling or soft-tissue thickening may develop around the involved MTP joint.

Swelling may become more noticeable after prolonged activity.

Stiffness

As disease progresses, the affected MTP joint may lose motion because of synovitis, articular collapse, osteophytes, or secondary arthritis.

Physical Examination

Range of Motion

The involved MTP joint may demonstrate reduced active and passive range of motion.

Motion can become progressively restricted in later stages.

Tenderness

Direct palpation over the metatarsal head and MTP joint typically reproduces the patient’s pain.

Swelling

Soft-tissue swelling around the joint may be present, particularly after activity.

Toe-Rise Test

Standing on the toes or performing a heel rise increases loading across the metatarsal heads and may reproduce pain.

Imaging

Plain Radiographs

Initial evaluation should include weight-bearing AP, oblique, and lateral radiographs of the foot.

Radiographic appearance varies according to the stage of disease.

Early Radiographic Findings

Early findings may include localized osteopenia, subtle subchondral lucency, sclerosis, or irregularity of the metatarsal head.

Radiographs can occasionally appear normal in very early disease.

Progressive Disease

With progression, the metatarsal head may become enlarged, flattened, sclerotic, and irregular.

Subchondral cystic changes and osteophytes may also develop.

End-Stage Disease

Advanced disease produces joint-space narrowing, fragmentation, deformity, and degenerative destruction of the MTP joint.

MRI

MRI is particularly useful when early disease is suspected but radiographs are normal or equivocal.

Typical findings include bone marrow edema and abnormalities of the subchondral bone consistent with osteonecrosis or osteochondral injury.

Bone Scintigraphy

Technetium bone scanning can demonstrate focal increased tracer uptake at the involved metatarsal head.

It may help identify occult disease, although MRI is generally more useful for defining early structural abnormalities.

Pathological Findings

Characteristic pathologic changes include synovitis, loose bodies, osteophytes, and osteonecrosis of the metatarsal head.

Metatarsal Head Necrosis

The marrow space may undergo fibrosis with areas of dead trabecular bone.

Subsequent resorption and structural weakening can lead to collapse of the articular surface.

Cartilage Damage

Progressive disease eventually results in articular cartilage loss and secondary degenerative arthritis.

Classification

Several classification systems have been proposed.

The best known is the Smillie classification, which describes progressive stages based largely on the structural and macroscopic appearance of the metatarsal head.

Although useful for describing severity, the classification does not always determine treatment reliably by itself.

Natural History

Freiberg disease may progress through stages of subchondral necrosis, collapse, remodeling, and secondary arthritis.

In some patients, remodeling ultimately produces a reasonably congruent articular surface and substantial improvement in pain.

Others develop persistent deformity or degenerative arthritis.

Differential Diagnosis

Idiopathic Synovitis

MTP synovitis can produce localized pain and swelling without the characteristic osseous abnormalities of Freiberg disease.

Inflammatory Arthritis

Inflammatory arthropathies may cause forefoot pain, swelling, stiffness, and multiple-joint involvement.

Acute Fracture

An acute metatarsal or osteochondral fracture should be considered when symptoms follow trauma.

MTP Sprain

Ligamentous injury around the MTP joint can produce pain and swelling without metatarsal head osteonecrosis.

Metatarsal Stress Fracture

A stress fracture may cause activity-related forefoot pain and focal tenderness and can resemble early Freiberg disease.

Morton Neuroma

Morton neuroma produces forefoot pain, often with burning or paresthesias radiating into the toes, typically from an intermetatarsal space rather than directly from the metatarsal head.

Treatment

General Principles

Treatment depends on the stage of disease, severity of pain, degree of articular collapse, and functional limitation.

Early disease is generally treated nonoperatively.

Activity Modification

Activities that reproduce pain should be reduced or temporarily avoided.

This commonly includes running, jumping, dancing, and other high-impact loading of the forefoot.

Immobilization and Footwear

Early-stage disease may be treated with a stiff-soled shoe, walking boot, or short walking cast to decrease motion and loading across the involved MTP joint.

Metatarsal Pad

A metatarsal pad placed just proximal to the affected metatarsal head can redistribute plantar pressure away from the painful joint.

Taping

Taping or strapping the involved toe can limit MTP motion and reduce mechanical irritation.

Medication

NSAIDs may be used to reduce pain and inflammatory swelling when appropriate.

Corticosteroid Injection

A carefully selected intra-articular corticosteroid injection may temporarily reduce symptomatic synovitis.

Such injections should be used judiciously and do not correct the underlying structural abnormality.

Surgery

Surgery is considered when substantial symptoms persist despite appropriate nonoperative treatment, particularly in patients with progressive collapse or mechanical joint symptoms.

Synovectomy

Synovectomy can be performed when persistent inflammatory synovitis contributes significantly to pain.

Joint Debridement

Debridement may include removal of fibrotic tissue, loose osteochondral bodies, and osteophytes.

This can improve motion and reduce mechanical symptoms.

Bone Grafting

Bone grafting of the metatarsal head may be considered in selected earlier-stage lesions when the subchondral bone is compromised but the articular surface has not yet undergone major collapse.

Dorsiflexion Osteotomy

A dorsiflexion osteotomy of the affected metatarsal can rotate relatively healthy plantar articular cartilage dorsally so that it articulates with the proximal phalanx.

This simultaneously unloads the damaged dorsal portion of the metatarsal head.

Resection Arthroplasty

Metatarsal head resection arthroplasty may be considered for severe end-stage disease in selected patients.

However, shortening and loss of the metatarsal head can alter forefoot load distribution.

Prosthetic Joint Replacement

Routine prosthetic replacement of the lesser MTP joint is generally not favored.

Potential problems include transfer metatarsalgia, bone resorption, loosening, and implant failure.

Follow-Up

Prognosis

The prognosis is generally favorable.

In many patients, the acute painful phase gradually resolves and is replaced by only an intermittent ache or mild activity-related discomfort.

Long-Term Outcome

Outcome depends on the degree of articular collapse and secondary arthritis.

Patients treated before extensive joint destruction generally have better preservation of motion and function.

Complications

Articular Collapse

Progressive subchondral failure can lead to flattening and collapse of the metatarsal head.

MTP Arthritis

Loss of joint congruity and cartilage can result in secondary degenerative arthritis of the second MTP joint.

Transfer Metatarsalgia

As the painful joint becomes mechanically unloaded, pressure may shift to adjacent metatarsal heads.

This can produce transfer metatarsalgia and plantar callus formation elsewhere in the forefoot.

Patient Monitoring

Patients should be monitored for pain, swelling, MTP range of motion, progression of metatarsal head collapse, development of arthritis, and ability to return to activity.

Repeat weight-bearing radiographs are useful when symptoms persist or worsen, particularly to assess structural progression and guide the need for operative treatment.