Surgical Management of Freiberg’s Infraction

Freiberg infraction is an osteochondrosis of a lesser metatarsal head, most commonly involving the second metatarsal.

In 1913, Freiberg originally documented six cases and used the term infraction to indicate incomplete fracture.

ANATOMY

An osteochondrosis is an insult to the blood supply to the epiphysis. In Freiberg infraction, it leads to avascular necrosis.

Freiberg disease is characterized by collapse of the dorsal articular surface, with relative preservation of the plantar surface of the involved metatarsal head.

PATHOGENESIS

Not fully understood but most likely multifactorial

Proposed etiologies include vascular insufficiency and potential genetic predisposition.

Thought to involve repetitive microtrauma and altered biomechanics

In our opinion, may be loosely compared to femoral head osteonecrosis

NATURAL HISTORY

Peak onset is between ages 11 and 17 years.

Incidence is uncertain but occurs in a 5:1 female-to-male ratio.

Typically unilateral but occurs bilaterally in 7% of cases

PATIENT HISTORY AND PHYSICAL FINDINGS

The classic presentation is activity-related pain and an antalgic gait, often worse when barefoot.

Tenderness to palpation, classically at the dorsal metatarsal head and metatarsophalangeal (MTP) joint

Decreased MTP joint range of motion, particularly with dorsiflexion

Pain and impingement with forced MTP joint dorsiflexion

Pain may also be present with forced MTP joint plantarflexion.

Periarticular hypertrophy with palpable dorsal metatarsal head bony prominence

MTP joint effusion, indicative of synovitis

IMAGING AND OTHER DIAGNOSTIC STUDIES

Although the aforementioned clinical findings are highly suggestive of Freiberg infraction, routine weight-bearing foot radiographs are recommended to confirm the diagnosis.

The radiographic Smillie classification remains a widely used staging system representing the spectrum of metatarsal head degeneration/collapse, from minimal involvement (simple dorsal metatarsal head flattening) to advanced disease (complete metatarsal head collapse and MTP joint destruction), which may be loosely compared to femoral head osteonecrosis.

Mild to moderate disease may be manifest only radiographically as flattening of the metatarsal head’s subchondral architecture.

In our experience, symptomatic patients most commonly present with intermediate stages, with the observed radiographic appearance being collapsed with or without fragmentation of the dorsal one-third to half of the metatarsal head; the plantar articular surface is typically preserved (FIG 1A,B).

Should plain radiographs fail to confirm a history and clinical examination suggestive of Freiberg infraction or if the diagnosis remains in question, magnetic resonance imaging (MRI) may prove useful.

MRI for Freiberg infraction generally demonstrates a dorsal metatarsal head with a hypointense signal on T1-weighted images and mixed signals on T2-weighted images.

MRI may also suggest metatarsal head flattening and dorsal osteophyte formation (FIG 1C).

Similar to MRI, technetium bone scans may detect early disease not evident on plain radiographs. With technetium bone scanning, Freiberg infraction typically appears as a photopenic center ringed by an area of hyperactivity on the involved metatarsal head. In our opinion, isolated technetium bone scanning is not indicated for Freiberg infraction.

Computed tomography may provide greater detail of subchondral collapse and dorsal metatarsal head prominence but is generally not indicated in the evaluation of Freiberg infraction (FIG 1D).

DIFFERENTIAL DIAGNOSIS

Metatarsal neck stress fracture

MTP joint synovitis (without suggestion of metatarsal head avascular necrosis and subchondral collapse)

MTP joint arthritis (without suggestion of metatarsal head avascular necrosis and subchondral collapse)

Neuroma, lipoma, ganglion cyst, or other soft tissue tumor

NONOPERATIVE MANAGEMENT

Limited weight bearing, with forefoot unloading and immobilization for 4 to 6 weeks

Gradually advance to a semirigid longitudinal arch support, with metatarsal support fitted in a stiffer-soled shoe to continue unloading of the involved MTP joint.

Progressive return to activities, with aforementioned orthotic and shoe modifications, as symptoms allow

Nonsteroidal anti-inflammatory drugs (NSAIDs) may diminish associated symptoms related to MTP joint synovitis.

Intra-articular corticosteroid injection should be used cautiously, as it may harm the residual articular cartilage or compromise the MTP joint’s ligamentous integrity.

Gait training may permit safe ambulation/running while compensating for the involved MTP joint’s stiffness; however, aggressive range-of-motion exercises for the affected MTP joint may aggravate impingement. We typically reserve physical therapy for patients who have had surgical management to improve the joint’s mechanics and to relieve mechanical impingement.

SURGICAL MANAGEMENT

Nonoperative treatment is first line. For patients who fail conservative treatment, the stage of disease generally dictates the planned surgical procedure.

For metatarsal heads with Freiberg infraction that have not progressed to dorsal subchondral bone collapse, with or without dorsal osteophyte formation, a joint synovectomy, dorsal cheilectomy, and/or decompression with bone grafting of the affected metatarsal head should be undertaken.

For patients who have gone on to subchondral bone collapse of the dorsal metatarsal head, with or without fragmentation, we typically perform a (subcapital) dorsiflexion osteotomy, bringing the healthier plantar articular surface dorsally to improve joint function.

For patients who have severe subchondral bone collapse and advanced MTP joint degeneration, consideration may be given to salvage procedures such as partial versus complete metatarsal head resection arthroplasty, or a soft tissue interpositional arthroplasty may be considered.

Preoperative Planning

Standard weight-bearing anteroposterior (AP), lateral, and oblique radiographs and potentially MRI are useful in assessing the severity of disease and determining the planned procedure.

Positioning

The patient is positioned supine on the operating room table with a support under the ipsilateral hip to limit external rotation of the leg.

We typically use a calf tourniquet.

Approach

The approach for all techniques involves a dorsal longitudinal incision overlying the affected (usually second) metatarsal. A curvilinear incision may also be used.