The Common Vein
Copyright 2010
Definition
The metatarsals of the forefoot are characterized by being 5 separate bones.
They are part of the bones of the foot. They consists of bone and cartilage.
The unique structural feature is that each metatarsal bone has a similar structure including a head, shaft/body, and base. The head has a convex articular surface. The base is wedge-shaped to articulate with the tarsal bones. The dorsal and plantar surfaces are rough to allow for ligamentous attachments. The bases of the 1st and 5th metatarsal are larger to allow for tendon attachments.
The first metatarsal articulates with the first cuneiform and the proximal phalanx. The first metatarsal is shorter and stouter than the other metatarsals. There are two sesamoid bones (medial and lateral) that are located on the plantar surface embedded in the tendons near the metatarsophalangeal joint.
The 2nd metatarsal articulates with all three cuneiforms and its proximal phalanx. It is the largest metatarsal bone.
The 3rd metatarsal articulates with the lateral or third cuneiform and its proximal phalanx.
The 4th metatarsal articulates with the lateral or third cuneiform, the cuboid, and its proximal phalanx.
The 5th metatarsal articulates with cuboid and its proximal phalanx. The tuberosity of the 5th metatarsal is lateral to the cuboid.
The second through fifth metatarsals have two ossification centers. The primary center is at the shaft and the secondary center is at the head. They both appear between ages 5-8. The first metatarsal has a secondary center that appears during the 3rd or 4th year proximally and the 6th or 7th year distally. The metatarsals as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in embryo.
The function of the metatarsals is to join the phalanges with the cuneiforms and cuboid. The metatarsal head bear about ½ of a person’s body weight.
Common diseases include arthritis, Lisfranc injury, fracture, stress fracture, metatarsalgia, Frieberg infraction, turf toe, Hallus Rigidus, Hallux Valgus/Bunion, and osteomyelitis.
Arthritis can occur as a result of aging and use (osteoarthritis), rheumatoid arthritis, or as a result of post-traumatic changes.
Stress fractures are very common of the 2nd and 3rd metatarsals due to being fixed during walking.
The peroneus brevis tendon can be avulsed off the base of the 5th metatarsal.
A Jones fracture is a transverse fracture through the base of the 5th metatarsal where the peroneus tertius inserts.
A Dancer’s fracture is a spiral fracture of the 5th metatarsal neck common in ballet dancers due to inversion injury while dancing.
A Lisfranc injury refers to fracture/dislocation of all the joints in the midfoot due to a hyperextension injury. Compartment syndrome may occur after this type of injury.
Metatarsalgia is a condition pain and inflammation in the sole of the distal foot due to overuse and stress on the metatarsal head.
Freiberg infraction is a condition of painful collapse of the articular surface of the second metatarsal head.
Turf toe is a sprain of the 1st metatarsophalangeal joint due to a hyperextension injury resulting in stretching the plantar capsule and plate.
Hallux Rigidus refers to arthritis of the 1st metatarsophalangeal joint resuling in pain and stiffening of the joint.
Hallux Valgus or a bunion refers to a deformity of the 1st metatarsophalangeal joint resulting in lateral deviation of the proximal phalanx and medial pressure on the 1st metatarsal head.
Metatarsus adductus is a congenital deformity of the foot where the metatarsal bones are adducted (deviated toward the midline) and the foot appears the shape of a lima bean.
Skew foot is a type of flat foot also known as a Z foot or serpentine foot. There is adduction towards the midline and plantar flexion of the metatarsals. The midfoot is abducted with lateral displacement of the navicular. The hindfoot is valgus (angled outward) with pronation and rotation of the talus. Essentially the toes are turned away from the midline and the hindfoot is rotated towards the midline.
Osteomyelitis is an infection of the bone typically due to bacteria.
Commonly used diagnostic procedures include clinical history, physical exam, plain radiographs, CT scan, bone scan, and MRI.
It is usually treated with either non-operative methods or operative methods. Fractures can be treated non-operatively or operatively. Arthritis, hallux valgus/bunion, and hallux rigidus can be treated with surgery, physical therapy, or NSAIDs. Osteomyelitis is treated with surgery and antibiotics. Lisfranc injury is treated non-operatively or operatively depending upon the level of displacement of the bones. Non-operative management is usually casting and non-weight bearing for 6 weeks. Operative treatment involves screws or k-wire fixation with subsequent non-weightbearing for 6 to 12 weeks. Metatarsalgia can be treated with orthotics, heel cord stretching, or surgery. Turf toe is treated with reducing activities and an orthotic device. Freiberg infraction is almost always treated nonoperatively with limited activity, immobilization, and/or orthotics. Surgery is rare for Frieberg infraction. Metatarsus adductus can be treated with passive stretching.
References
Elstrom J, Virkus W, Pankovich (eds), Handbook of Fractures (3rd edition), McGraw Hill, New York, NY, 2006.
Koval K, Zuckerman J (eds), Handbook of Fractures (3rd edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.
Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Wheeless’ Textbook of Orthopaedics: Anatomy and Radiographs of the Midfoot (http://www.wheelessonline.com/ortho/anatomy_and_radiographs_of_the_midfoot