Procedure Practice 08/15/99 - Coding Recommendations

Feature Article 08/15/99:

Bones

Anatomy - Fractures - Treatments and Procedures

Fractured bones are commonly treated in physicians’ offices, emergency departments, outpatient surgical units, and, in cases of multiple or complex fractures, in the acute care hospital. This month, we learn about bone structure and function, discuss types of fractures, and review the many options available to treat these injuries.
  

Anatomy

Skeletal Functions

Bones perform five basic functions:

1. Support - The skeleton supports soft tissues and enables the body to maintain its shape and posture.
     
2. Protection - Bones protect the brain and spinal cord and the heart, lungs, and major blood vessels of the thoracic cavity.
     
3. Motion - In concert with their attached muscles, bones act as levers to produce body movement.
     
4. Hematopoiesis - The production of red blood cells, white blood cells, and some platelets occurs within the red bone marrow.
     
5. Storage - Bones serve as storage sites for calcium, phosphorus, and fat.
      

Bone Structure

Bone is a specialized type of connective tissue. It contains a large amount of intercellular substance that bathes widely separated cells. This intercellular substance, called osteoid, is composed primarily of calcium phosphate and calcium carbonate salts. These salts together are called hydroxyapatites. As the salts are deposited in the fibers of the intercellular substance, the bone tissue hardens (ossifies). Mature bone cells are called osteocytes. A typical long bone consists of the following parts:

1. The diaphysis is the shaft of the bone.
    
2. The epiphyses are the ends of the bone.
     
3. The metaphyses are areas between the shaft and epiphysis. In children with growing bones, the metaphyses are the growth plates where calcified cartilage is reinforced and then ultimately replaced by bone.
    
4. Articular cartilage covers the bony epiphyses to cushion joints.
     
5. Periosteum is a dense fibrous cover around the surface of the bone. Its outer fibrous layer is made of blood and lymph vessels and nerves that pass into the bone. The inner layer is the osteogenic layer. Elastic fibers, blood vessels, and osteoblasts are found here. Osteoblasts are immature bone cells that are responsible for new bone growth and repair. The periosteum is essential for bone growth, repair, and nutrition. It also serves as a point of attachment for ligaments and tendons.
    
6. The medullary (or marrow) cavity is the space within the bone shaft that contains fatty yellow marrow in adults.
    
7. The endosteum is a layer of osteoblasts that lines the medullary cavity.

Bone is not a completely solid, homogeneous substance. Although it seems very hard when seen by the naked eye, at a microscopic level, bone contains numerous spaces between its hard components. These spaces provide channels for blood vessels and make bones lighter. Depending upon the size and distribution of spaces, bone mass is classified as either compact or cancellous.

Compact bone contains few spaces. It is deposited in a layer over cancellous bone tissue. The layer of compact bone is thicker in the bone’s diaphysis than in the epiphyses. Compact bone provides protection and support and helps long bones resist the stresses placed upon them. Compact bone has a concentric ring structure which cancellous bone does not. Blood vessels and nerves from the periosteum penetrate compact bone through channels called Volkmann’s canals. The blood vessels of these canals connect with blood vessels and nerves of the medullary cavity and those of the central (Haversian) canals. Haversian canals run longitudinally through bone. They are surrounded by concentric rings of calcified intercellular substance called lamellae. Between the lamellae are small spaces called lacunae where osteocytes are found. Osteocytes are mature bone cells. Tiny channels called canaliculi radiate in all directions from the lacunae and connect with other lacunae and Haversian canals. This intricate network is formed throughout compact bone and provides routes for the delivery of nutrients to osteocytes and for the removal of waste products. Each Haversian canal with its surrounding lamellae, lacunae, osteocytes, and canaliculi is called an osteon.

In contrast to compact bone, cancellous bone does not contain true osteons. Cancellous bone consists of an irregular latticework of thin plates called trabeculae. Within the trabeculae are the small spaces called lacunae, and osteocytes are located within the lacunae. Blood vessels from the periosteum penetrate through to the cancellous bone and the osteocytes are nourished directly from blood circulating through the medullary cavity.

Unlike compact bone, cancellous bone becomes increasingly hollow toward its center. Cancellous bone is composed of an irregular latticework of thin plates called trabeculae which is surrounded by numerous large spaces. Cancellous bone makes up most of the tissue of short, flat, and irregularly shaped bones as well as most of the epiphyses of the long bones. Cancellous bone provides a storage area for red and yellow bone marrow.
  

Bone Replacement and Remodeling

Remodeling is the replacement of old bone tissue by new bone tissue. Compact bone is formed by the transformation of cancellous bone. Bone shares with skin the feature of replacing itself throughout adulthood. Remodeling allows injured or worn bone to be replaced with new strong tissue. Remodeling also allows bone to serve as a storage area for calcium. The blood continually trades off calcium with the bones, removing it when other tissues (muscles, for example) need more of this element, and then resupplying it with dietary calcium to prevent loss of bone mass.

Osteoclasts are the cells responsible for resorption of bone tissue. A delicate homeostasis is maintained between the osteoclasts as they remove calcium and the osteoblasts as they deposit calcium to create new bone. Normal bone growth in children and bone replacement in adults depends upon several factors. First, sufficient amounts of phosphorus and calcium must be included in the diet. Second, dietary intake of vitamins A, C, and D must be adequate, because these vitamins enable the body to properly use calcium and phosphorus. Finally, the body must make the proper amounts of those hormones responsible for bone tissue activity.
  

Blood and Nerve Supply

Bone is richly supplied with blood, and blood vessels are especially abundant in portions of bone with red bone marrow. Blood vessels pass into the bone via the periosteum and then branch into the Haversian canals on their way to the marrow. Arteries are accompanied by veins, which leave the bone via numerous vascular foramina in the epiphyses. Although nerve supply is not extensive, vasomotor nerves accompany the blood vessels as they course through bone tissue, and some sensory nerves occur in the periosteum. Periosteal nerves are primarily pain sensors.

Fractures

Pathology

A fracture is the most common bone lesion and is defined as a break in the continuity of a bone or a part of its mineralized structure. A fracture may be the result of an excessive impact, rotation, bending, or other mechanical force acting on previously normal bone, or it may be the consequence of an unnoticed or trivial injury of previously diseased bone. Many factors influence fracture repair, among them the severity of injury, type of fracture, vascular damage, infection, age of patient, hormonal and nutritional factors, and systemic disease.

The immediate effects of a fracture are to break the bone’s hard outer cortex and trabeculae, tear the periosteum, and sever the bone’s blood vessels, resulting in extravasation and pooling of blood and blood clots between the bone fragments beneath the periosteum and in the adjacent muscle and other soft tissues. Many bone cells and other cells at the fracture site undergo necrosis as a result of physical injury and ischemia. An acute inflammatory response occurs in regions of tissue injury and necrosis.

The process of fracture repair proceeds both internally (endosteally) and externally (subperiosteally) and can be divided into three stages occurring at approximately the following time intervals: by the second or third day, organization of hematoma and exudate by granulation tissue; by the fifth or sixth day, beginning formation of primitive or woven bone around the fracture (primary callus) which bridges the gap between the bone fragments and immobilizes them; by six weeks and beyond, replacement of callus by mature lamellar bone (secondary callus) and establishment of bony union.

Soon after injury, the fracture hematoma begins to clot, a network of fibrin strands is formed, connective-tissue cells from the surrounding tissues migrate along the network, capillary endothelial buds enter the coagulated mass, and the hematoma eventually becomes organized and converted into granulation tissue.

Meanwhile, osteoblasts begin to deposit organic bone matrix (osteoid) on the existing cortex and trabeculae or other solid tissue base. The osteoid becomes mineralized and forms a primitive bone callus around the fracture, bridges the fracture gap, plugs the medullary cavity, and immobilizes the bone fragments. At this stage, a periosteal shell of mineralized callus may first appear on an x-ray film.

Next, the bulky callus is slowly decreased in size and replaced by strong lamellar bone, and firm bony union is established. The process of bone remodeling by osteoclastic resorption and osteoblastic reformation takes place over subsequent weeks or months. The final result of fracture healing in a setting of good alignment, close positioning, and firm immobilization of bone fragments is to attain a normal anatomical and functional reconstitution of the bone cortex and medulla.
  

Common Terms and Eponyms

Common types of fractures as well as some eponyms and terms pertaining to specific fracture sites include the following:

Closed or simple - A break in the bone that does not protrude through the skin

Open or compound - A break in which broken ends of bone protrude through the skin

Comminuted - A break in which the bone splinters at the site of impact and smaller bone fragments are found between the two main fragments

Compression - A fracture produced by compression of bones against one another, e.g., a vertebral compression fracture

Greenstick - A fracture which occurs in children and in which one side of the bone breaks while the other side bends

Impacted - A fracture in which one bone fragment is driven into the cancellous tissue of another bone

Spiral - In this type of fracture the bones are twisted apart.

Transverse - The break occurs at a right angle to the long axis of the bone

Avulsion - These fractures occur at a soft tissue (i.e., muscle, tendon, ligament) insertion site on bone when soft tissue along with fragments of bone are pulled away from the insertion site

Intraarticular - A fracture that occurs within a joint capsule

Stress/Fatigue - A partial fracture caused by inability to withstand repeated stress, often seen in athletes as training increases in duration, frequency, or difficulty; occurs often in metatarsals or in the distal third of the fibula

Pathologic - A fracture caused by weakened bone structure rather than by trauma

Displaced - A fracture in which the bone fragments do not maintain proper position and alignment

Nondisplaced - A fracture in which the bones maintain proper position and alignment

Hairline - A fracture without separation of the fragments with a resultant hairlike appearance to the break, sometimes seen in skull fractures

Blow-out - A fracture of the orbital floor produced by a blow to the globe with force transmitted from the globe to the orbit

LeFort I - A facial fracture involving a horizontal fracture of the maxilla above the apices of the teeth

LeFort II - A mid-facial fracture in which the principal fracture lines meet at an apex near the nasal bones

Tripod - A facial fracture of the zygomatic processes of the maxilla and frontal bones and the arch of the zygomatic bone

Monteggia’s - An ulnar fracture with dislocation of the radial head

Colles’ - A fracture of the distal radius with dorsal displacement of the distal fragment

Smith’s - A fracture of the distal radius with volar displacement of the distal fragment

DeQuervain’s - A fracture of the navicular bone of the hand with dislocation of the lunar bone

Boxer’s - A fracture of the neck of the 5th metacarpal, often caused by forcefully punching an object

Intertrochanteric - A femoral fracture that occurs along the line from the greater to the lesser trochanter just distal to the femoral neck

Pertrochanteric - A fracture of the femur that passes through the greater trochanter

Subcapital - A fracture of the femur at the junction of the head and neck

Transcervical - A fracture of the femoral neck

Supracondylar - A fracture above a bony condyle, usually refers to the condyles of the distal femur

Bimalleolar/Pott’s/Dupuytren’s Fracture - A fracture of both malleoli on either side of the ankle; i.e., a fracture of the distal fibula and the distal tibia

Trimalleolar - A fracture of both malleoli plus an additional fracture of the posterior tip of the tibia

Lisfranc - A fracture of one or more of the bones at the site of the arched tarsometatarsal joint in the midfoot. This joint is composed of the 1st through 3rd metatarsals and the 1st through 3rd cuneiform bones. Joint dislocation often accompanies a fracture at this site.

March - A metatarsal stress fracture

Pilon - A fracture of the distal metaphysis of the tibia that extends into the ankle joint

Shepherd’s - A fracture of the posterior process of the talus

  

Treatments and Procedures

The treatment of fractures can be simple or quite complicated. The goal of any treatment is to realign the bone fragments and restore normal function as soon as possible. As discussed above, bones heal in a very complex way that requires the transformation of tissue from hematoma to callus to new bone. The type of treatment depends upon the fracture location, the general health of the patient, and the existence of associated injuries. To heal properly, fracture fragments must be in correct anatomical position, and they must remain stable in this position during the healing process.
 

Closed Treatment

Closed treatment of a fracture means that the fracture site is not surgically opened and therefore not directly visualized by the physician. Closed fracture treatment includes treatment without manipulation, treatment with manipulation/reduction, and skin or skeletal traction.

• Without manipulation describes the simple application of an immobilizing/stabilizing device. Examples of these devices include splints, all types of casts, wraps, or bandages. Nondisplaced fractures in which bones maintain their proper alignment are treated with this method.
    
• Closed treatment with manipulation, or closed reduction, is done when fracture fragments need to be repositioned before they heal. The broken bone is not exposed and no incision is made. Following reduction, the fracture fragments are usually held in position by casting.
   
• Skin or skeletal traction requires application of force to reinforce stability of the fracture fragments. Application of traction causes the muscles to act as internal splints to maintain the bones in proper alignment. Skin traction applies longitudinal force on a limb with a felt, foam, or strapping apparatus applied directly to the skin. Skeletal traction uses force via use of a pin, wire, screw, or clamp that penetrates the bone. The hardware is drilled into and across the bone and out through the skin, with force then applied to the external hardware.
    

Open Treatment

Open treatment involves surgical exposure of the fracture site in order to realign the fracture fragments. The bone ends are visualized and once the fracture is reduced, the physician may use either internal or external fixation devices to maintain proper anatomical alignment.
 

Internal Fixation

Internal fixation uses various types of hardware, such as plates, rods, nails, pins, wires, and screws to stabilize a fracture that was either nondisplaced or already previously reduced. Internal fixation is a method of fracture stabilization, not a fracture reduction procedure. The surgeon places hardware into the bone to secure anatomical position of the fracture fragments. Internal fixation does not always require that a fracture site be opened.

• Percutaneous skeletal fixation is an internal fixation method that does not require direct exposure of the fracture site. The surgeon inserts hardware (screws, Steinmann pins, Kirschner wires) into the bones across the fracture site under radiologic imaging, usually x-ray or fluoroscopy.
   
• Intramedullary nailing or rodding is an internal fixation method used to stabilize shaft fractures. The fracture is first manipulated into position under radiologic guidance. Then the surgeon makes an incision either proximal or distal to the fracture site, and threads a nail down the medullary canal, again under radiologic guidance, through the bone and across the site of the fracture. An interlocking screw is sometimes applied at right angles to the nail, further stabilizing the fracture. The fracture site is not opened during this procedure.
   

External Fixation

This treatment method employs placement of percutaneous pins proximal and distal to the fracture fragments with application of a frame that connects the pins externally. The device keeps the pins at a constant distance and stabilizes the bone setting. The external fixation system stays in place until the fracture has healed sufficiently to maintain stability without the frame. Examples of this type of external frame system are Spinelli, Monticelli, Unifix, Orthofix, and Hoffman fixators.
 

Fracture Debridement

Fracture debridement is a procedure that is sometimes necessary to clean and prepare fracture sites prior to reduction and stabilization of the bone fragments. The wound site of a compound fracture may be contaminated with foreign debris such as glass, dirt, metal, gravel, etc., and the tissue layers at the wound edges may be torn and jagged. Closed fractures may have associated skin lacerations, burns, or deep abrasions. Debridement involves prolonged irrigation and cleansing of the wound site, removal of foreign material and devitalized tissues, and exploration of soft tissue injuries. The goal of the procedure is to leave only viable tissue that the surgeon may then close or leave open and to reduce the amount of swelling and hemorrhage usually associated with this type of contaminated wound.

Practice Makes Perfect!

Are you ready for some hands-on practice?

Read the patient report(s) on our procedure practice page. Assign the appropriate codes and then compare your answers with our coding recommendations. Good luck!

Back to:
Top - Anatomy - Fractures - Treatments and Procedures
   

If you have comments or suggestions about our code selections or about any topic on our Coding Edge® pages, please e-mail us at codingedge@lagunamedsys.com.