Orthopedic Coding Alert

This ICD-10 example shows you why you should know these terms.

Bone comprises of a rigid structure, which is based on dense connective tissue. A normal human bone is made up of the following essential macro and micro elements:

Periosteum: The periosteum is the dense fibrous membrane that is composed of irregular connective tissue and covers the bony surfaces. It comprises of an outer fibrous layer and inner cellular layer.

Medullary Membrane: Medullary membrane is a thin layer of highly vascular and areolar connective tissue lining the cylindrical medullary cavity and haversian canal. This membrane has osteogenic, hematopoietic and fracture healing properties.

Marrow: Marrow is a vascular substance found in the cylindrical cavities of the long bones and sternum, and facilitates the production of red blood cells, white blood cells, and platelets.

Blood Vessels and Nerves of Bone: The periosteum of the bones is extensively invaded by blood vessels and nerves. The vast distribution of blood vessels inside the bony canals constitutes the complex vasculature, which facilitates nutrition to the respective bones. Most non-orthopedic surgeons, including many other medical professionals, are not aware that bone bleeds. In some cases, bones can bleed quite briskly.

Haversian Canals (Canals of Havers): These can be explored through a transverse section of the bone. A Haversian canal typically comprises of a central hole within the bony region, which runs parallel to the long axis of bone. The canal is surrounded by numerous concentric rings or layers, which are also known as lamellae. The individual layers along with central canal constitute a haversian system (which is also known as an osteon).

Lamellae: The bony osteon comprises of multiple layers that have the same focus, which overlap the central haversian canal. These layers are termed as lamellae.

Lacunae: These appear as fusiform opaque spots between lamellar spaces and consist of the bone-corpuscle. Lacunae act as channels to provide nutrition to the Haversian system.

Canaliculi: These are very small canals connecting multiple lacunae together inside the haversian system.

Canaliculi extend from one specific lacuna and communicate to another series of lacunae within the haversian canal.

Perichondrium: The non-vascularized layer of dense irregular connective tissue that covers the elastic and hyaline cartilage is termed as perichondrium. This layer primarily works as the growth layer of cartilage.

Osteoblasts: The inner surface of periosteum is invaded by the mononucleate formative cells that act to provide nutrition to the bony matrix during the early stages of bone development. These formative cells are termed as osteoblasts. However, osteoblasts descend in number as one ages, thereby leading to the gradual degradation of the bony tissues.

Osteoclasts: The giant cells that remain involved in the absorption of the bone matrix are termed as osteoclasts. These are particularly loacted in red marrow, inside the Howship’s foveolae (bony pits or cavities). Osteoclasts control the quantity of osteoblasts by enhancing the bone resorption process.

Medullary spaces: Medullary spaces are the cancellous tissue intervals that exist as a substitute of Haversian canals in the thin plates of bone, and remain confined between bone trabeculae.

Epiphysis: The articular end of a long bone, which is surrounded by cartilage, is defined as epiphysis. This portion of bone is further segregated into subchondral zone, including the epiphysial line.

Diaphysis: The shaft of a long bone (diaphysis) is constituted by a section of compact bone that contains bone marrow. Shaft indicates the mid section of the bone that contains components like medullary cavity, nutrient foramen, endosteum, periosteum and adipose tissue.

Metaphysis: The extended portion of the long bone (that lies adjacent to the epiphysis) is termed as metaphysis. Growth plates (or the epiphysial plates) are present as a part of the bony metaphysis, which particularly serves as the growth center of the long bone and facilitates the ossification process.

Now that you’ve learned the parts of the bone, let’s apply this to your diagnosis coding.

Example: Suppose your physician documents that a patient has a nontraumatic acute slipped upper femoral epiphysis of the right hip. (Note: The epiphysis means the articular end of a long bone, which is surrounded by cartilage.) How should you report this?

You should report M93.013 (Acute slipped upper femoral epiphysis [nontraumatic], right hip).

Documentation note: Encourage your physician to specify the location of the affected hip to get to a more detailed code.