Freiberg Disease

Introduction

Freiberg disease is illustrated as a self-limiting progressive imbalance of normal bone growth (osteochondrosis) in the long bone of the foot known as the second metatarsal bone. It is a very rare disease that was first identified in 1914 by Dr. Alfred Freiberg. He described this condition in 6 patients who had pain around the second metatarsal during any kind of activity. Radiographs showed a sclerotic and compacted metatarsal head.¹ He linked this state to any kind of trauma, but later it was clarified that trauma alone is not adequate to cause it. Usually, the second and third metatarsals are affected but the fourth and fifth metatarsals may be involved in rarer cases.² Even though it is considered an unusual occurrence, this avascular necrosis of the second metatarsal is the fourth most frequent osteochondrosis to be known.³

Causes

The two most widespread theories that explain the occurrence of Freiberg Disease are trauma and vascular compromise. However, many investigators believe that it can occur due to multiple factors.^4,5 Additionally, other systemic disorders which have been studied to have a role in this disease development include systemic lupus erythematosus, diabetes mellitus, and hypercoagulability.^6,7

1. Trauma

Studies related to trauma being a major factor in Freiberg disease occurrence are controversial. The first time this disease was defined by Dr. Freiberg, he reported that 4 out of his 6 patients had experienced traumatic events. Other scientists like Smillie ⁸ supported the idea that repetitive trauma can cause such an effect on the joints. The comparatively increased length of the second metatarsal makes it more inclined to withstand higher stresses during the normal walk.^5,9 Any kind of dysfunctional alignment like hallux valgus or hallux rigidus that interrupts the usual weight-bearing role of the first ray causes increased load stress on the second metatarsal.¹⁰ Another reason for increased trauma may be shoe size or type. High heels cause increased stress on this joint. However, not many studies have been able to prove this connection^4,5

2. Vascular

These joints mainly receive blood from the vascular network of the dorsal metatarsal artery and medial deep plantar artery.¹¹ Compression of this vascular network due to joint effusion or any swelling may decrease the blood supply in these joints. Thus, this deficiency in blood supply to the second metatarsal contributes to the development of Freiberg disease due to the occurrence of necrosis at the second metatarsal¹²

Epidemiology

This is the only type of osteochondrosis that is present more commonly in females, with a ratio of 5 to 1.⁶ Freiberg disease affects both feet equally. Characteristically, only one lesion is observed in a foot. However, bilateral involvement can present, even though it has been observed in very few cases (approximately <10% ).¹³ The regions affected are as follows: the second metatarsal is the most affected region (68%): the third metatarsal affected in around 27% of cases; the fourth in only 3%; and the fifth metatarsal very rarely affected. The peak age of onset of this disease is between 11 to 17 years.¹⁴

Symptoms

Patients usually complain about the pain mainly localising at the metatarsal head region. Patients describe that they feel like they are walking on something hard like a stone. On clinical examination, it has been observed that the toe generally has a swollen appearance, and may also be elevated in some cases. In more advanced stages, crossover deformities or hammer toes may develop.¹⁴

Classification

The most widely used classification to define Freiberg’s disease has been given by Smillie.⁸

Stage I: Initially, a constricted fissure fracture advances in the ischaemic epiphysis. Adjacent cancellous bone generally appears sclerotic. In comparison with nearby metaphyseal bone, the epiphysis is undersupplied or there is a complete lack of blood flow

Stage II: The subchondral bone collapses once the absorption of cancellous bone happens in the metatarsal head. The superimposing cartilage is decreased, pivoting on the intact cartilage at the plantar facet, modifying the contour of the articular surface

Stage III: At this stage, further absorption happens which causes the central portion to descend further, leaving projections on either side. The plantar cartilage remains integral

Stage IV: By this stage, repair of the anatomy of the foot is not possible as the central portion of the articular surface has descended deep enough to fracture the plantar hinge. Marginal protuberances have fractured to form loose bodies

Stage V: The last and final stage exhibits arthrosis (degeneration) with marked levelling. Only the plantar section of the metatarsal cartilage maintains the original contour. Most of the loose bodies have decreased in size and the shaft of the metatarsal is stiffened

Diagnosis

Freiberg’s disease is usually diagnosed clinically and confirmed with plain films

• Radiographs: Radiographs of the affected foot should be performed at lateral, anteroposterior, and oblique angles.¹⁵ However, early radiographic assessment of this disease is often not possible as the most primitive radiographic appearance of Freiberg’s disease is illustrated approximately 3 to 6 weeks after the beginning of symptoms. It is generally described as the widening of the subtle joint space¹⁶
  
• Magnetic Resonance Imaging (MRI): MRI of a painful metatarsal can help in the early detection of Freiberg’s disease.¹⁷ MRI images reveal modifications within marrow intensity. Important features detected by MRI are: the location of articular preservation; articular compromise; the presence of intra-articular loose fragments; osseous defects; and bone marrow oedema. Hence, evaluation by MRI is important both for staging as well as for treatment planning¹⁸
  
• Bone Scan: Early-stage disease may illustrate a photopenic zone that is encircled by a very active revascularized collar. The image is then magnified and optimised for good resolution in the circumscribed areas¹³

Treatment

Non-operative management

Since these lesions are mainly asymptomatic, the objective of non-operative treatment is to attain more tolerable symptoms.

One of the ways to manage this disease is to modify the size or type of the shoe one wears. The standard shoe should be the one that is very comfortable and puts the least possible pressure on the foot, especially at the affected point. Even though custom shoe modifications are available, usually a graphite footplate and other commercially available shoes are equally helpful at a low cost.

Another option is to get steroid injections. These medications help to lower inflammation and redness at the joint. However, this is a temporary solution as there are major side effects associated with its continuous and prolonged use.

Regenerative medicine is also coming into play to help in the management of Freiberg Disease. Use of stem cells or platelet-rich plasma may help in repairing cartilage deficiency associated with this disease.¹⁸

Operative management

Operative management of Freiberg disease is generally planned for patients whose pain and functional limitations are not managed with non-surgical methods. Surgical treatment can further be categorised into “joint preserving” and “joint sacrificing”.

While planning surgical treatment, it is important to take into consideration points such as the length of the second metatarsal, joint deformity and length or mobility of the first ray. However, there is no clear agreement as to which method is best.¹⁸

Joint preserving

It involves methods like osteotomy, debridement and cartilage replacement.

• Osteotomy: The two main types of osteotomies are dorsiflexion and shortening. The purpose of the dorsal closing wedge osteotomy is to cause articulation of the plantar articular cartilage with the proximal phalanx, while the objective of the shortening osteotomy is to decompress the abnormal metatarsal head.¹⁹ Osteotomy is an advantageous technique because it uses the patient's own tissue to repair a cartilage surface at the foremost articulating part of the joint
  
• Debridement: It involves the removal of any loose bodies, protuberant osteophytes and delaminated areas of cartilage along with the hypertrophic synovium. This method is mainly performed in patients with pain due to bony impingement²⁰
  
• Cartilage replacement: It can consist of osteochondral allograft, autogenous osteochondral grafting and chondral allograft

Joint sacrificing

• Metatarsal head resection:  In the past, removal of the diseased metatarsal head at the later stages of the disease had been encouraged.²¹ However, this method causes an elevated risk of transfer metatarsalgia, undesirable reduction in the involved digit, and hallux valgus^20,22
  
• Interpositional arthroplasty: Autogenous or allograft soft tissue grafts have been used as biological spacers. They are associated with positive results.^23,24 Moreover, if the graft fails, the procedure does not have much effect on other additional reconstructive options that may be performed
  
• Synthetic implants: Ceramic, silicone, and titanium devices have been used in a small number of cases but with varied results.^21,25,26 Several problems have been observed with the use of these devices - failure or loosening of prosthesis, osteolysis, infection, and dysfunction of the diseased toe causing transfer metatarsalgia. For these reasons and because of the lack of consistent successful studies, artificial joint arthroplasty is not recommended for the treatment of late-stage Freiberg disease

Summary

Freiberg disease is a rare disease with varying presentations over a wide range of age groups. Treatment options must take into regard the stage of pathology, patient’s age, overall foot mechanics and symptoms. Despite substantial radiographic findings, patients often do not show any symptoms and hence do not require any major treatment. However, the late-stage disease may require more assertive surgical treatments to sustain the toe length and lower the chance of transfer metatarsalgia. Hence, further studies are required to support any individual method of treatment.