In forefoot pain, the lateral 2 to 5 toes, and the corresponding metatarsophalangeal joint or submetatarsal head pain, are the most problematic conditions for clinicians. After performing a detailed examination and test, the diagnosis is usually not difficult to confirm and treatment is relatively uncomplicated. However, forefoot pain is usually diagnosed and treated by a foot and ankle surgeon, and may require special care in identification by a general orthopedic surgeon because of an incomplete understanding of this area. This article provides a brief explanation of the most common hammer toe of the forefoot.
Hammer toe (Hammer toe) is a common deformity of the toes, defined as a state of deformity in which the metatarsophalangeal joint is hyperextended, the proximal interphalangeal joint is flexed, and the distal interphalangeal joint is straightened. The deformity is usually seen in the 2nd and 3rd toes and is usually differentiated from hammer toe by claw toe and mallet toe. (See Figure 1)
Clinical manifestations
Pain and limited shoe wear are the main clinical signs of hammertoe. Severe deformities can be complicated by dorsal corns of the interphalangeal joint or severe painful calluses at the tip of the toe. When the deformity is present, the patient is severely restricted in wearing shoes, sometimes even loose athletic shoes. Walking becomes an ordeal and the long-term deformity can cause severe functional limitations of the patient’s foot.
Physical examination
The main thing to distinguish is whether the deformity is pliable or rigid. Stiff deformities usually require interphalangeal arthroplasty (DuVries procedure), while flexible deformities can usually be treated with tendon transposition.
It is then important to note whether the deformity is located in the metatarsophalangeal joint or the proximal interphalangeal joint, or both.
The drawer test (Lachman’s test), which examines the function of the metatarsal plate and collateral ligaments, is performed. It is usually considered positive when there is a dorsal extension shift of more than 2 mm or a shift of more than 50% of the distal toe. It is important that the hand is held in the correct position, otherwise a false positive result may occur.
Etiology
There are three main causes of hammertoe formation: bunion, overgrowth of the second metatarsal, and wearing pointed shoes. In these three conditions, the toe is subjected to abnormal stress over time and gradually develops a deformity. Clinically, you may also see patients with a short 1st metatarsal who develop a hammertoe due to excessive stress on the lateral metatarsals.
The presence of a hammertoe is usually followed by an imbalance in muscle strength and instability of the metatarsophalangeal joint in the foot.
Decreased muscle strength in the intrinsic muscles of the foot can result in inadequate flexion strength of the metatarsophalangeal joint and inadequate dorsiflexion strength of the interphalangeal joint. This results in a relative overstrength of the long and short extensor tendons and the long and short flexor tendons of the toe, and a hammertoe deformity.
Muscle strength imbalance and long term deformity of the toe can result in loss of interphalangeal joint mobility, from a pliable deformity, to a stiff deformity.
In addition, deformed toes cause damage, malfunction, or fracture to the stable structures of the metatarsophalangeal joint, such as the collateral ligaments and metatarsal plates, which are subjected to excessive stress during foot walking. This results in crossed toes or “floating toes”. By precise definition, a toe with a metatarsal plate injury does not have the same mechanism of injury as a toe with a bunion. However, the result of long-term stress is essentially the same. Clinically speaking, the treatment of these deformities is also the same and is discussed here together (Figure 2).
The deformity is usually seen in the 2nd and 3rd toes (Figure 3). The usual stabilizing structures of the toe are the metatarsal plate and the lateral collateral ligaments of the metatarsophalangeal joint. Collateral ligament injuries can cause instability of the toe in the coronal plane, while metatarsal plate injuries cause instability in the sagittal plane. If both are present, a crossed toe may be present.
Treatment
There are not many treatment options for hammertoe. Conservative treatment requires a crescent-shaped toe pad under the toe to accommodate the deformity if it is a stiff deformity, or a hammertoe pad to limit it if it is a flexible deformity. However, the long-term results of conservative treatment are not good. The patient’s pain will reappear after a period of treatment.
The surgical options for lateral toe deformities are more limited. The usual methods used are the Weil osteotomy (metatarsal head shortening osteotomy), the Girdlestone-Taylor procedure (flexor tendon to extensor tendon transposition), and the Z-lengthening of the extensor tendon. In case of rigid deformity, arthroplasty (DuVries procedure) can be performed at the interphalangeal joint.
Treatment of claw toe is similar to hammertoe, but stiff claw toe is more dependent on shortening of the metatarsal osteotomy or soft tissue release.
All of these treatments have complications, such as recurrence of toe deformity, toe stiffness, toe weakness, or residual pain, but the incidence varies. The most common unsatisfactory outcome for patients is stiffness. Abnormal toe muscle strength cannot be fully restored by surgery, so it is important to communicate with the patient before surgery that the purpose of the surgery is to relieve pain and wear shoes, and that the patient understands the purpose of the surgery before proceeding. If the patient has high expectations, it is not suitable for surgical management.
In patients with metatarsal plate injuries, “floating toe” is the most common postoperative complication, and this complication may be related to the lack of metatarsal plate repair.