The Common Vein
Copyright 2010
Definition
The tibia of the musculoskeletal system is characterized by being the second largest bone in the body, but the strongest weightbearing bone in the body. It is colloquially referred to as the shin bone or shank bone. It was named after the greek aulos flute.
It is part of the anteromedial lower leg. The tibia is part of both the knee and the ankle joints. It consists of bone and cartilage tissue once mature.
Its unique structural features include the tibial plateau, shaft, and plafond. There are many bony prominences along the tibia including the intercondylar eminence, Gerdy?s tubercle, tibial tuberosity, soleal line, nutrient foramen, tibialis posterior groove, fibular notch, and medial malleolus. The blood supply is from the nutrient artery and from periosteal vessels of the anterior tibial artery. The bone is more vertical and parallel in males. In females, the tibia tends to be slightly oblique.
The tibial plateau consists of the medial and lateral condyle. The articular surface of the plateau is mostly flat. The medial articular surface is slightly concave, while the lateral articular surface is slightly convex. The articular surface accommodates the large femoral condyles.
The intercondylar eminence consists of the intercondylar tubercles. These tubercles fit into the intercondylar fossa between the femoral condyles to allow for articulation. These tubercles are the attachment points for the menisci and knee ligaments.
The anterolateral tibial tubercle is also known as Gerdy?s tubercle. This is the insertion of some of the fibers iliotibial band providing some lateral support to the knee.
The fibular articular facet is located on the posterolateral proximal tibia. This is the site where the tibia is in contact with the fibular head.
The tibial shaft is vertical and triangular in cross section. There are three distinct borders of the tibial shaft; anterior, interossesous/lateral, and posterior. The anterior border is very prominent and can be felt on palpation of the shin. The location is just under the skin. The interosseous border is between the tibia and fibula where the interosseous membrane helps to connect the bones. Posteriorly, the tibia has the soleal line and nutrient foramen.
The tibial tuberosity is located on the superior and anterior portion of the tibia. It is the site of attachment of the patellar ligament. The patellar ligament is important for knee extension as it is made up of fibers originating from the quadriceps muscles.
The pes anserine region is located on the superior and medial aspect of the tibia. This is the site of attachement of the gracilis, sartorius, and semitendinosis. There is a bursa located in this region known as the pes anserine bursa.
The medial malleolus is the distal flare out of the tibia and serves as the origin of the medial/deltoid ligamentamous complex that stabilizes the medial ankle. The medial malleolus articulates with the talus and is covered with articular cartilage.
The interosseous membrane runs on the lateral portion of the tibia and helps to connect the tibia and fibula. There is an opening the proximal interosseous membrane for the anterior tibial vessels.
Inferiorly the articulation between the fibula and tibia occurs on the tibia at the fibular notch.
Posteriorly, the tibia has a rough ridge known as the soleal line. Distal to the soleal line is the nutrient foramen where the tibia receives part of its blood supply into the bone marrow. Just proximal to the ankle joint is the groove to the tibialis posterior tendon.
The tibia has three ossification centers. The body is a primary ossification center that appears at 7 weeks (fetal). The proximal ossification center is secondary appearing at birth and fusing at 20 years. The distal ossification center is secondary appearing during the 2nd year and fusing at 18 years. The tibia as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in embryo.
The function of the tibia is to allow for weight bearing and to serve as attachments for muscles and ligaments to move and stabilize the joints. The structure of the bone flaring out both medially and laterally helps to increase joint contact area and dissipate weight transfer. .
Common diseases include arthritis, fracture, tumor, bursitis, osteomyelitis, tibia hemimelia/deficiency, pseudoarthrosis, stress fractures, Osgood Schlatter, and Blounts Disease.
Fracture of the tibia can occur at the promimal tibia (tibial plateau), tibial tubercle (avulsion), tibial shaft, and at the distal tibia plafond (ankle). Compartment syndrome can occur with tibial fractures.
Osteomyelitis is an infection of the bone usually due to bacteria.
Tumors can either be primary or from metastasis. A few primary tumors that can occur in bone include leukemia, lymphoma, neuroblastoma, osteoblastoma, osteosarcoma, osteoid osteoma, enchondroma, and Ewing?s Sarcoma.
Rickets and other calcium depleting conditions can cause the tibial shaft to increase in convexity or bow.
Pseudoarthrosis is a condition of a false joint that leads to anterior tibial bowing.
Osgood Schlatter is a condition of juvenile traction osteochondritis where there is partial avulsion of the tibial tuberosity. It tends to be more common in early adolescent boys.
Blounts Disease is a growth disorder of the medial proximal tibial physis resulting in a varus deformity (bowlegged).
Tibial hemimelia/deficiency is a condition of abnormal development of the tibia or complete lack of the tibia.
Commonly used diagnostic procedures include clinical history, physical exam, x-ray, MRI, bone scan, and CT scan.
It is usually treated with internal or external surgical fixation or non-operative approaches for fractures and pseudoarthrosis. Tibial bursitis is treated with physical therapy, NSAIDs and steroid injections. Tumors can be treated with surgery, chemotherapy, and radiation. Rickets is treated with replacing vitamin D. Stress fractures are treated with rest, physical therapy, and dietary modification. Arthritis is treated initially with physical therapy, NSAIDs, steroid injections, and braces. Arthritis can also be surgically treated with arthroscopic debridement or knee replacement. Tibia hemimelia can be treated with Syme amputation or centralization of the fibula. Blounts Disease when it does not correct itself typically is corrected with a surgery on the growth plate. Osgood Schlatter disease is typically treated non-operatively, rarely do the ossicles need to be surgically removed.
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: Tibia Fracture Menu (http://www.wheelessonline.com/ortho/menu_for_the_tibia_tibia_frx)