The fibula is a bone in the lower leg. When mature, it consists of bone and cartilage. Cartilage is present on surfaces that cover the joints and allows for a smooth gliding surface for bones to move along on. In the growing child, the fibula consists of all cartilage, but then ossifies or becomes bone starting at 8 weeks of fetal life and continues to ossify in stages until age 25.
Structure
The fibula is the smaller of the two bones making up the lower part of the leg in between the knee and ankle joints. In cross section, the fibula is triangular in shape. The major components of the fibula are its head, shaft and the lateral malleolus. The head of the fibula is located closest to the knee joint. The shaft is between the head and lateral malleolus. The lateral malleolus is the part of the fibula bone that forms the outer portion of the ankle joint.
Function
The function of the fibula is to have muscle attachments and to help form joints. The muscles that attach to the fibula help to move the knee and ankle joints. The fibula is an important bone for the formation of the ankle joint. For the knee joint, the fibula is not part of the hinge joint of the knee, but helps to stabilize the outer knee through its ligament attachment to the femur by the lateral collateral ligament.
Fracture
Fibular fractures can occur at the head, shaft or at the lateral malleolus. Some injuries involve a fracture and then an associated dislocation or disruption of a joint. Fractures can occur from a wide variety of causes including trauma, crush injuries, stress fractures and as result of a twisting injury to the ankle. Conditions such as osteoporosis or a bone tumor can weaken the bone and lead to increased risk for fracture. The fibular shaft can often be fractured along with the tibial shaft in trauma.
Congenital Deficiency
Congenital deficiency of the fibula or fibular hemimelia is the lack in some infants to form a full-sized fibula when developing prior to birth. The limb anomaly can range from a partial absence to a complete absence of the fibula. According to "Wheeless' Textbook of Orthopaedic Surgery," the condition is most commonly unilateral and more common in males. Patients may have a shortened lower extremity, abnormal knee and lower extremity alignment, ligament deficiencies of the knee, a malformed ankle joint, fusion of foot bones or tarsal coalition and absent forefoot and toe bones. Patients can be treated with simple shoe lifts, limb lengthening or an amputation depending upon the severity of the fibular deficiency.
Fibular Grafts
The fibula can often be used as a bone graft in other locations in the body, according to the AAOS Comprehensive Orthopaedic Review. The graft can be taken with either the blood vessel to the fibula attached or unattached. The reason that the fibula can be used for a bone graft is because the fibula is not an absolutely essential bone in the lower extremity for structural support.
References
- "Clinically Oriented Anatomy (5th ed)"; Dr. K. Moore, Dr. A. Dalley (eds); 2006.
- "AAOS Comprehensive Orthopaedic Review"; Dr. Jay Lieberman (ed); 2008.
- "Handbook of Fractures"; Dr. Kenneth Koval, Dr. Joseph Zuckerman (eds); 2006.
- Wheeless' Textbook of Orthopaedics: Fibular Hemimelia
