Copyright 2009
Author John Udall MD
Definition
The fibula is a long, thin, cylindrical bone that runs parallel to the tibia and plays a role in both knee and ankle stability. It has relatively immobile attachments to the tibia both proximally and distally and has a strong syndesmotic ligament which runs the entire length of the bone which provides structural support of the two bones in between their proximal and distal attachments. It serves as the attachment site for the biceps femoris of the thigh, the lateral collateral ligament, and the posterolateral corner structures of the knee.
Its unique structural features include its distal extension, the lateral malleolus, which serves as the origin of the lateral ankle ligaments which are the most commonly injured ligaments in ankle sprains in athletes.
It articulates with tibia proximally to form a very sturdy, immobile arthrodial joint that is composed of very strong ligaments.
The function of the tibia is to act as a scoffold for the attachment of lateral muscles of the leg and to act asa a minor weight bearing bone of the leg (about 1/6 of the weight distributed up the leg from the ankle is transmitted through the fibula, wheras 5/6 is distributed through the tibia).
Common diseases include common fractures to the distal fibula (lateral malleolus fractures). Since the fibula is not a major weight bearing bone, arthritis will not involve the fibula as it does the proximal and distal weight bearing surfaces of the tibia. The anterior talofibular ligament is the most commonly injured ankle ligament in sprains, and attachmes to the lateral malleolus of the fibula
Commonly used diagnostic procedures include plain x-rays to evaluate fractures. The anterior drawer test is a posterior to anterior load applied to the ankle to check stability of the ankle when their is suspician of an anterior talofibular ligament tear
Distal nondisplaced fractures of the fibula can be treated with casting, bu when they are seen in conjunction with tibia medial malleolar fractures, surgery becomes necessary. Surgical intervention includes plate and screw fixation of the bone. Minor ankle sprains are treated with immobilization and activity modification, wheras more chronic ankle injuries that result in persistant instability of the ankle, sometimes require reconstruction or repair of the ligaments.