DEFINITION

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

 

 

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FIG 1 • A. Right foot AP radiograph showing central subchondral collapse of the second metatarsal head. B. Oblique radiograph of same right foot demonstrating flattening of the dorsal second metatarsal head; note preservation of the plantar subchondral architecture. C. Sagittal T1- weighted magnetic resonance image demonstrating articular and subchondral flattening of the second metatarsal head. D. Sagittal computed tomography detailing dorsal metatarsal head osteophyte formation.

 

 

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.

 

Careful soft tissue handling is maintained. The extensor tendon is retracted, and the capsule overlying the MTP joint is split longitudinally.

 

 

The capsule is elevated from the proximal phalanx and metatarsal to expose the joint. The proximal phalanx is then maximally plantarflexed to expose the metatarsal head.

 

For all cases of Freiberg infraction that we have treated operatively, we have performed a comprehensive synovectomy.

 

 

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TECHNIQUES

• Dorsal Cheilectomy

With the metatarsal head fully exposed, the articular surface is examined. If the cartilage is preserved in the presence of a dorsal osteophyte, as in this case, dorsal cheilectomy alone is performed.

The microsagittal saw is used to remove the osteophyte from distal to proximal, along with any diseased dorsal metatarsal head articular cartilage, similar to the surgical management of the first metatarsal head in hallux rigidus (TECH FIG 1).

Range of motion is checked, particularly forced dorsiflexion after removing the osteophyte, to ensure impingement has been eliminated and satisfactory range of motion has been reestablished. As with hallux rigidus, a blunt elevator may be used to mobilize plantar capsular contractures to further improve dorsiflexion.

 

 

 

 

TECH FIG 1 • Resection of the dorsal osteophyte with microsagittal saw.

• Bone Grafting of Metatarsal Head

   

  Albeit relatively rare, MRI scanning may demonstrate precollapse Freiberg disease involving a symptomatic subchondral cyst and relative preservation of metatarsal head.

   

  In select cases, we have been successful in relieving symptoms by decompressing and bone grafting the cyst without disrupting the intact subchondral bone.

   

   

   

  TECH FIG 2 • A. Drilling of the involved metatarsal head from a dorsal approach. B. Decompression of the cyst with a small curette. C. Harvest of calcaneal bone graft from the ipsilateral calcaneus. D. Autograft is packed into the defect in the metatarsal head.

   

   

  If the cartilage is found to be intact after exposure, a dorsal drill hole is created and the metatarsal cyst is evacuated with a curette (TECH FIG 2A,B).

   

  Calcaneal bone graft is harvested from the ipsilateral foot and packed densely into the cyst (TECH FIG 2C,D).

   

  26

• Dorsal (Subcapital) Dorsiflexion Osteotomy

  Osteotomy

   

  For patients with collapse of the articular surface, we favor a subcapital dorsiflexion metatarsal head/neck osteotomy (TECH FIG 3A,B).

   

  This technique uses a dorsal closing wedge osteotomy to excise the unhealthy cartilage and rotate the intact healthy plantar articular cartilage to replace it.

   

   

  After dorsal longitudinal approach to the MTP joint, the metatarsal head is inspected (TECH FIG 3C). The dorsal osteophyte is removed, either with a microsagittal saw or with a rongeur (TECH FIG 3D).

   

  If upon inspection the dorsal articular surface is collapsed and the plantar cartilage is preserved, we perform a dorsally based wedge osteotomy, removing the diseased cartilage with extraction of the wedge (TECH FIG 3E,F).

   

  Ideally, the dorsally based wedge osteotomy should not penetrate the plantar cortex. Instead, both limbs of the osteotomy should meet at or immediately short of the plantar cortex.

   

  This way, the osteotomy may be collapsed dorsally, maintaining plantar periosteum and stability.

   

   

   

  TECH FIG 3 • A. Preoperative AP right foot radiograph in a 19-year-old female college basketball player, with a symptomatic second MTP joint. B. Oblique radiograph. Note dorsal osteophyte versus dorsal osteophyte and preserved plantar subchondral bone architecture. C. Full exposure of the involved metatarsal head. D. Dorsal prominence removal with a microsagittal saw. E. Dual converging osteotomies, creating the dorsal closing wedge osteotomy using the microsagittal saw to excise the diseased dorsal distal aspect of the metatarsal head. F. Extraction of the diseased portion of metatarsal head.

   

   

  Prior to closing osteotomy, the bony surfaces may be carefully drilled to facilitate healing.

   

  With closure of the osteotomy, the intact plantar cartilage is rotated into position to articulate with the proximal phalanx.

  Kirschner Wire Stabilization

   

  The osteotomy may be stabilized with a Kirschner wire (K-wire) placed across the osteotomy from proximal to distal. Because the plantar cortex remains intact and stable, we typically suture the wedge into place with one or two sutures (TECH FIG 4A).

   

  In this case, in which considerable correction was required, we opted to add a temporary longitudinal K-

  wire first placed antegrade from the MTP joint across the toe and then retrograde across the MTP joint into the metatarsal (TECH FIG 4B).

   

  The K-wire's position is confirmed fluoroscopically.

   

  When using a K-wire, we generally leave it in place for 4 weeks.

   

  Aggressive rotation of the metatarsal head (ie, a large wedge resection) increases the risk for transfer metatarsalgia.

   

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  TECH FIG 4 • A. Elevation of the plantar articular surface and fixation with nonabsorbable sutures. B. Given considerable correction and potential for instability, K-wire is placed across MTP joint to further stabilize the osteotomy.

• Metatarsal Head Arthroplasty versus Capsular Interpositional Arthroplasty

Metatarsal Head Reshaping

 

Even with severe metatarsal head degeneration (TECH FIG 5A-D), we recommend against complete metatarsal head excision, as it may lead to transfer metatarsalgia.

 

We favor reshaping and partial excision of the involved lesser metatarsal head without capsular interposition (TECH FIG 5E). Although this procedure does not fully relieve symptoms, in our experience, it often leads to less pain, less impingement, and improved function with little risk of creating transfer metatarsalgia (TECH FIG 5F,G).

Capsular Interpositional Arthroplasty

 

Interpositional arthroplasty for Freiberg infraction has not, in our hands, been as successful as when it is performed for first MTP joint arthritis (TECH FIG 6).

 

 

 

TECH FIG 5 • A 67-year-old woman with left hallux valgus, long-standing second metatarsal head Freiberg infraction, and more advanced second MTP joint arthritis. A. AP left foot radiograph; note advanced metatarsal head collapse and joint arthrosis. B. Same patient's oblique left foot radiograph. C. Intraoperative image demonstrating same patient's severe, advanced metatarsal head collapse and joint degeneration. (continued)

 

 

Adequate decompression is necessary because the joint will remain symptomatic if too little bone is resected. However, overzealous metatarsal head bone resection to accommodate the capsular interposition may lead to transfer metatarsalgia.

 

Capsular interpositional arthroplasty for hallux rigidus also includes excision of the proximal phalanx base; given poor results with lesser toe proximal phalanx base excision for claw toe correction, we advise against excision of the lesser toe proximal phalanges to accommodate a lesser MTP joint capsular interpositional arthroplasty.

Closure and Aftercare

 

 

Both the capsule and subcutaneous layers are closed with 3-0 absorbable suture. The tourniquet is released and meticulous hemostasis is obtained.

 

Care is taken to ensure that the toes are well perfused.

 

The skin is reapproximated with 4-0 monofilament suture to a tensionless closure.

 

A sterile dressing is used to protect the wound and a mildly compressive dressing is placed.

 

 

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TECH FIG 5 • (continued) D. There is some intact residual plantar articular cartilage but not enough to consider subcapital osteotomy. E. Metatarsal head is reshaped, accepting minimal residual metatarsal head cartilage but eliminating impingement and decompressing the joint. F. Note limited intact residual plantar cartilage. G. Satisfactory passive MTP joint dorsiflexion without impingement demonstrated.

 

 

 

TECH FIG 6 • Capsular interpositional arthroplasty. A. Essentially no residual metatarsal head articular cartilage noted on direct inspection. Dorsal cheilectomy performed. B. Dorsal capsule preserved to allow for an interpositional arthroplasty. Important to ensure that this MTP joint is relatively loose and is not overstuffed with capsule, which will create impingement symptoms. C. Dorsal capsule is sutured to plantar plate.

 

 

PEARLS AND PITFALLS

Instability of the

dorsiflexion osteotomy

• Remember to avoid violating the plantar cortex during the wedge resection.

• Use a dorsal suture to approximate the osteotomy. If necessary, place a longitudinal K-wire.

Transfer

metatarsalgia

• Avoid being overly aggressive in the dorsal wedge resection; otherwise,

  transfer metatarsalgia may result.

• In advanced disease, avoid complete resection of the metatarsal head; instead, perform a partial metatarsal head resection arthroplasty only.

 

 

 

POSTOPERATIVE CARE

 

If we did not perform an osteotomy, weight transfer to the forefoot progresses relatively rapidly over the first 2 weeks in a stiffer-soled postsurgical shoe and transition to regular shoe and physical therapy is permitted when the wound is stable.

 

Suture removal is typically at 10 to 14 days.

 

If an osteotomy was performed, we typically splint the patients with the ankle in neutral position, particularly if the toe has been stabilized with a K-wire. The splint protects against inadvertent displacement of the osteotomy and/or K-wire.

 

The patient returns to the office at 10 to 14 days for possible suture removal and another splint. If the patient is capable of remaining off of the forefoot, a boot may be placed in which the patient may weight bear through the heel.

 

The pin is removed in the office at 4 to 5 weeks (FIG 2).

 

 

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FIG 2 • Early radiographic follow-up suggests improved metatarsal head architecture.

 

We routinely obtain simulated weight-bearing foot radiographs at 4 weeks.

 

 

Even if the radiographs suggest satisfactory bony apposition at the osteotomy site, we recommend restricting weight transfer to the forefoot for a full 6 weeks.

 

At 6 weeks, the patient may transfer to a boot or postoperative shoe and gradually progress to full weight bearing over the subsequent 2 weeks.

 

We recommend that the patient be fitted for an offloading orthotic with metatarsal support as he or she transitions to a regular shoe between 6 and 8 weeks.

 

 

 

FIG 3 • Same patient as TECH FIG 3. A 19-year-old female basketball player at 2-year follow-up after dorsiflexion osteotomy for second metatarsal head Freiberg infraction. A. Healed dorsal incision. B. Satisfactory forefoot range of motion. C. She developed transfer metatarsalgia of the third metatarsal head. D. This was effectively treated conservatively with semirigid longitudinal arch support and metatarsal support to unload the third metatarsal head.

 

 

Our standard postoperative protocol for forefoot surgery is Xeroform over the incision, a soft dressing, and immediate weight bearing in a hard-soled postoperative shoe.

 

If an osteotomy is performed, the patient is placed into a wellpadded posterior/sugar-tong splint with no pressure on the involved toe, and weight bearing is protected. The pin remains for 6 weeks.

 

We recommend return to full activities only with resolved MTP joint symptoms and radiographic improvement in involved metatarsal head's radiographic appearance.

 

OUTCOMES

 

There is a lack of meaningful data that goes beyond simple case series regarding outcomes after treatment of Freiberg disease, with much of the recommendations based on anecdotal experience.

FIGS 3 and 4 show follow-up after dorsiflexion osteotomy for second metatarsal head Freiberg infraction in two patients.

 

 

 

 

COMPLICATIONS

Infection, wound complications, and nerve deficit are no more prevalent than in other forefoot procedures.

Vascular compromise is possible yet rare. In our hands, delayed capillary refill may occur if the toe is pinned in too much plantarflexion.

Joint stiffness typically persists after surgery, albeit without dorsal impingement pain provided the dorsal metatarsal head prominence is removed.

Physical therapy may help to improve motion but rarely can regain physiologic motion.

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FIG 4 • Two-year follow-up after dorsiflexion osteotomy for second metatarsal head Freiberg infraction. A. AP view. Note marked improvement and restoration of near-anatomic joint congruency. B. Oblique view of left foot.

 

In our experience, the most common complication after dorsiflexion osteotomy is transfer metatarsalgia. Fortunately, the overload of the adjacent metatarsal head is rarely as bothersome as was the untreated Freiberg infraction.

Transfer metatarsalgia is generally well managed with a semirigid longitudinal arch support with metatarsal support and that unloading of the affected adjacent metatarsal heads.

 

 

SUGGESTED READINGS

1. Freiberg AH. Infraction of the second metatarsal bone, a typical injury. Surg Gynecol Obstet 1914;19:191-193.

    

    

2. Gauthier G, Elbaz R. Freiberg's infraction: a subchondral bone fatigue fracture. A new surgical treatment. Clin Orthop Relat Res 1979;(142): 93-95.

    

    

3. Katcherian D. Treatment of Freiberg's disease. Orthop Clin North Am 1994;25:69-81.

    

    

4. Mandell GA, Harke HT. Scintigraphic manifestations of infraction of the second metatarsal (Freiberg's disease). J Nucl Med 1987;28(2):249-251.

    

    

5. Smillie IS. Treatment of Freiberg's infraction. Proc R Soc Med 1967;60(1): 29-31.

    

    

6. Smith TW, Stanley D, Rowley DI. Treatment of Freiberg's disease. A new operative technique. J Bone Joint Surg Br 1991;73:129-130.

    

    

7. Talusan PG, Diaz-Collado PJ, Reach JS Jr. Freiberg's infraction: diagnosis and treatment. Foot Ankle Spec 2014;7(1):52-56.