Classification system to help with brachymetatarsia of the foot

Brachymetatarsia of the foot manifests itself with the presence of at least one shortened metatarsal . In this article, titled "Brachymetatarsia Classification," we will examine the types and how they manifest. Visually, the foot is quite disconcerting and functions bizarrely. This deformity comprises two main components: a bony component, involving the metatarsal and corresponding phalangeal bones , and a soft tissue component . In congenital brachymetatarsia, insufficient growth of the metatarsal and phalangeal bones occurs. In contrast, in the traumatic version , phalangeal length is normal.

Externally, brachymetatarsia is recognizable because one toe is shorter and more withdrawn than the adjacent toes, which lean toward the space left by the shorter toe. If the foot has more than one shortened metatarsal, it is called brachymetatarsia . The anatomy of this fascinating anomaly reveals that the attachment of the lesser metatarsal is located at the neck of the bone, while that of the first metatarsal is at the base. This positioning has different impacts on the position of the foot itself.

Lamm classification and brachymetatarsia: how is it done?

Foot brachymetatarsia affects approximately one in 1000 people, with a mysterious predilection for women, as shown by a recent study that found a 9:1 ratio compared to men. Furthermore, 47% suffer predominantly from bilateral brachymetatarsia . Of the 300 metatarsals observed in the study, 58% belonged to the fourth metatarsal, which is the most affected.

Surgeons use various metatarsal lengthening techniques , ranging from acute to gradual, each with its own complications. One of the main challenges is ensuring that the metatarsophalangeal joint (MTPJ) does not lock or dislocate during lengthening. A practical solution is " bridging ," in which the MTPJ is fixed during the bone's distraction phase.

However, greater amounts of lengthening carry a greater risk of complications, such as joint dislocation, chondrolysis , and postoperative stiffness . To avoid these problems, the osteotomy is performed as far from the joint as possible, preferably at the proximal metaphyseal-diaphyseal junction.

A practical guide to the Lamm classification for brachymetatarsia

Brachymetatarsal deformities can be varied. Lamm's classification identifies three main types:

• Type A: includes normally formed metatarsals, but with a reduced length.
• type B: involves a curvature of the metatarsal bone.
• type C: presents joint irregularities in the head of the metatarsal and in the base of the phalanges.

In addition to types A, B, and C, there are others that identify which metatarsal is short or hypoplastic . For example, a patient with a short fourth metatarsal, diaphyseal curvature , and an incongruent joint would be classified as 4ABC.

Acute lengthening with bone grafting offers advantages, including the lack of external fixation. However, it also has disadvantages, such as the need for a donor bone for the graft and the requirement to avoid weight bearing on the foot for a certain period. 

Lamm's classification in the surgical revision of brachymetatarsia

The Lamm classification also plays a fundamental role in surgical revisions. These procedures are known for their complexity, often due to the persistence of type B or C deformities. Thanks to the advanced use of CT and MRI , understanding of joint abnormalities and their influence on the success of lengthening has improved.

A stiff or dislocated MTPJ requires surgical revision: an external fixator can help distract the joint to maintain long-term function.

The connection between hallux valgus and brachymetatarsia

Hallux valgus often occurs together with brachymetatarsia. In fact, 41% of patients present this dual complication. Generally, the hallux deformity is corrected along with metatarsal lengthening using internal or external fixation techniques.

Book your visit with SmartHallux

Fortunately, the complexity of brachymetatarsia is now finally understood and better managed thanks to the Lamm classification. This revolutionary system allows us to predict the best surgical technique to adopt. However, the surgeon's experience remains the key to successfully addressing this problem. Relying on the professional orthopedists at SmartHallux can make all the difference. Using cutting-edge surgical techniques and cutting-edge technological solutions, they will resolve your foot problems without visible symptoms. In a short time, you will be back to living without pain and walking normally. Book now using the online form on our website.