Diseases of the Musculoskeletal System and Connective Tissue
(ICD-10-CM Chapter 13, Codes M00-M99)
Learning Objectives
2. Identify pertinent anatomy and physiology of the musculoskeletal system and connective tissue
3. Identify diseases of the musculoskeletal system and connective tissue
5. Identify common treatments, medications, laboratory values, and diagnostic tests
6. Explain the importance of documentation as it relates to MS-DRGs for reimbursement
Abbreviations/Acronyms
ALIF anterior lumbar interbody fusion
AxiaLIF axial lumbar interbody fusion
DEXA dual-energy x-ray absorptiometry (bone density)
DIC disseminated intravascular coagulation
DJD degenerative joint disease
DLIF direct lateral lumbar interbody fusion
ICD-9-CM International Classification of Diseases, 9th Revision, Clinical Modification
ICD-10-CM International Classification of Diseases, 10th Revision, Clinical Modification
ICD-10-PCS International Classification of Diseases, 10th Revision, Procedure Coding System
IV intravenous
JRA juvenile rheumatoid arthritis
MRI magnetic resonance imaging
MS-DRG Medicare Severity diagnosis-related group
NSAIDs nonsteroidal anti-inflammatory drugs
PLIF posterior lumbar interbody fusion
PV percutaneous vertebroplasty
SLE systemic lupus erythematosus
TLIF transforaminal lumbar interbody fusion
XLIF extreme lateral lumbar interbody fusion
ICD-10-CM Official Guidelines for Coding and Reporting
Please refer to the companion Evolve website for the most current guidelines.
13. Chapter 13: Diseases of the Musculoskeletal System and Connective Tissue (M00-M99)
a. Site and laterality
Most of the codes within Chapter 13 have site and laterality designations. The site represents the bone, joint or the muscle involved. For some conditions where more than one bone, joint or muscle is usually involved, such as osteoarthritis, there is a “multiple sites” code available. For categories where no multiple site code is provided and more than one bone, joint or muscle is involved, multiple codes should be used to indicate the different sites involved.
1) Bone versus joint
For certain conditions, the bone may be affected at the upper or lower end, (e.g., avascular necrosis of bone, M87, Osteoporosis, M80, M81). Though the portion of the bone affected may be at the joint, the site designation will be the bone, not the joint.
b. Acute traumatic versus chronic or recurrent musculoskeletal conditions
Many musculoskeletal conditions are a result of previous injury or trauma to a site, or are recurrent conditions. Bone, joint or muscle conditions that are the result of a healed injury are usually found in chapter 13. Recurrent bone, joint or muscle conditions are also usually found in chapter 13. Any current, acute injury should be coded to the appropriate injury code from chapter 19. Chronic or recurrent conditions should generally be coded with a code from chapter 13. If it is difficult to determine from the documentation in the record which code is best to describe a condition, query the provider.
c. Coding of Pathologic Fractures
7th character A is for use as long as the patient is receiving active treatment for the fracture. Examples of active treatment are: surgical treatment, emergency department encounter, evaluation and treatment by a new physician. 7th character, D is to be used for encounters after the patient has completed active treatment. The other 7th characters, listed under each subcategory in the Tabular List, are to be used for subsequent encounters for treatment of problems associated with the healing, such as malunions, nonunions, and sequelae.
Care for complications of surgical treatment for fracture repairs during the healing or recovery phase should be coded with the appropriate complication codes.
See Section I.C.19. Coding of traumatic fractures.
d. Osteoporosis
Osteoporosis is a systemic condition, meaning that all bones of the musculoskeletal system are affected. Therefore, site is not a component of the codes under category M81, Osteoporosis without current pathological fracture. The site codes under category M80, Osteoporosis with current pathological fracture, identify the site of the fracture, not the osteoporosis.
1) Osteoporosis without pathological fracture
Category M81, Osteoporosis without current pathological fracture, is for use for patients with osteoporosis who do not currently have a pathologic fracture due to the osteoporosis, even if they have had a fracture in the past. For patients with a history of osteoporosis fractures, status code Z87.310, Personal history of (healed) osteoporosis fracture, should follow the code from M81.
2) Osteoporosis with current pathological fracture
Category M80, Osteoporosis with current pathological fracture, is for patients who have a current pathologic fracture at the time of an encounter. The codes under M80 identify the site of the fracture. A code from category M80, not a traumatic fracture code, should be used for any patient with known osteoporosis who suffers a fracture, even if the patient had a minor fall or trauma, if that fall or trauma would not usually break a normal, healthy bone.
Apply the General Coding Guidelines as found in Chapter 5 and the Procedural Coding Guideline as found in Chapters 6 and 7.
Anatomy and Physiology
The musculoskeletal system is made up of muscles, bones, ligaments, tendons, cartilage, and the joints they form. The purposes of the musculoskeletal system are to provide a framework and to protect the internal organs. Bones also are important for hematopoiesis and for storing calcium and phosphate. Hematopoiesis is the development of blood cells that occurs in the bone marrow and lymphatic tissue of normal adults.
A good grasp of anatomy is essential in coding conditions of the musculoskeletal system. It is important to know that the femur is the long bone in the thigh area, and that the radius and the ulna are two bones in the forearm. Pictures are best for illustrating the locations of the skeletal structures (Figure 19-1) and muscles (Figure 19-2). It is particularly important to understand the terms used in the musculoskeletal chapter to describe the location of structures relative to the body as a whole or to other body structures (Figure 19-3). Anterior or ventral describes the front of the body or an organ. Posterior or dorsal relates to the back of the body or an organ. The terms medial and lateral describe the position of the body or an organ relative to the median sagittal plane that divides the body in half. Medial refers to a structure that is closer to the median plane than is another structure in the body. The eyes are medial to the ears. Lateral refers to a structure that is to the side of the body. The ears are lateral to the eyes. The terms superior (above) and inferior (below) describe the position of the body or an organ relative to the vertical axis of the body. The shoulders are superior to the hips, and the ankles are inferior to the knees. Other terms that may be used are cranial, which means toward the head, and caudal, which means towards the tail. Proximal (closer to the point of reference) and distal (farther from the point of reference) are often used to describe a location in the limbs. The shoulder is proximal to the elbow, and the wrist is distal to the elbow. Supine refers to lying on the back, face up. Prone is lying on the stomach, face down.
The joints are the means of joining two bones together; they assist with body movement. Ligaments are dense fibrous bands of connective tissue that provide stability for the joint. Ligaments can be injured by overstretching or tearing (sprain). Tendons are the connective tissue that attaches muscle to bone. Tendons are susceptible to strain injuries. The fascia is the tissue just below the skin that covers and separates the underlying layers of muscle.
Disease Conditions
Diseases of the Musculoskeletal System and Connective Tissue (M00-M99), Chapter 13 in the ICD-10-CM code book, are divided into the following categories:
| CATEGORY | SECTION TITLES |
| M00-M02 | Infectious arthropathies |
| M05-M14 | Inflammatory polyarthropathies |
| M15-M19 | Osteoarthritis |
| M20-M25 | Other joint disorders |
| M26-M27 | Dentofacial anomalies, including malocclusion, and other disorders of the jaw |
| M30-M36 | Systemic connective tissue disorders |
| M40-M43 | Deforming dorsopathies |
| M45-M49 | Spondylopathies |
| M50-M54 | Other dorsopathies |
| M60-M63 | Disorders of muscles |
| M65-M67 | Disorders of synovium and tendon |
| M70-M79 | Other soft-tissue disorders |
| M80-M85 | Disorders of bone density and structure |
| M86-M90 | Other osteopathies |
| M91-M94 | Chondropathies |
| M95 | Other disorders of the musculoskeletal system and connective tissue |
| M96 | Intraoperative and postprocedural complications and disorders of musculoskeletal system, not elsewhere classified |
| M99 | Biomechanical lesions, not elsewhere classified |
Many of the conditions in Chapter 13 are coded based on site and laterality. Sites may include the bone, joint, or muscle involved. According to the guidelines, if a condition affects the portion of the bone at the joint, the site designation will be bone, not the joint.
Infectious (M00-M02) and Inflammatory Arthropathies (M05-M14)
Arthropathy is a disease that affects the joints. The term arthropathy is generic, and symptoms and treatment will depend on the cause of the arthropathy. Common causes include:
Infectious—due to an infection of the joint
Crystal—due to diseases such as gout that deposit crystals in the joint
Diabetic—a manifestation of diabetes
Neuropathic—a manifestation due to nerve damage around the joint
Enteropathic—a type of arthritis that is related to colitis such a Crohn’s or ulcerative colitis
Rheumatoid arthritis (RA) is a chronic, inflammatory, systemic disease that affects the joints, often causing deformity (Figure 19-4). RA is one of the most severe and disabling forms of arthritis. Damage may extend beyond the joints, affecting the heart and blood vessels and producing damage within the layers of skin.
Juvenile rheumatoid arthritis ( JRA) affects children, usually between the ages of 2 and 5 years. Various forms of JRA may affect only a few joints, may affect many joints, or may be systemic in nature (also known as Still’s disease).
Exercise 19-1
Assign codes to the following conditions.
| 1. Juvenile RA, left knee | _______________ |
| 2. Arthritis bilateral hips due to Crohn’s disease | _______________ |
| 3. Rheumatoid lung disease | _______________ |
| 4. Septic arthritis, right shoulder due to MRSA | _______________ |
| 5. Idiopathic chronic gout, left wrist | _______________ |
Osteoarthritis (M15-M19) and Other Joint Disorders (M20-M25)
Osteoarthritis
Osteoarthritis is a type of arthritis that develops as the result of wear and tear on the joints. It occurs because of breakdown and loss of cartilage within the joints (Figure 19-5). Osteoarthritis (OA) or degenerative joint disease (DJD), the most common form of arthritis, is more common in the elderly. Weight-bearing joints such as the knees and hips are often affected. The most common symptoms include sore and stiff joints, particularly in the morning or with changes of weather. Edema and deformity may also be present. Treatment depends on the severity of the condition and the success of conservative medical treatments (i.e., anti-inflammatory medications, exercise, steroid injections). In severe cases, surgery may be required to replace affected joints.
Primary osteoarthritis is an idiopathic condition that occurs in previously intact joints and has no apparent initiating factor. Primary osteoarthritis is related to the aging process and typically occurs in older individuals. Secondary osteoarthritis refers to degenerative disease of the joints that results from a predisposing condition such as trauma or disease. Secondary osteoarthritis may occur in relatively young individuals and usually affects the joints of one area.
Recurrent dislocations are not coded as an injury even if due to trauma. After the initial dislocation, the joint becomes less stable and requires less force to dislocate the joint again. The most common sites for recurrent dislocation to occur are shoulders, fingers, and knees.
Exercise 19-2
Assign codes to the following conditions.
| 1. Pain both knees due to DJD | _______________ |
| 2. Loose body in left knee joint | _______________ |
| 3. Talipes planus, right (acquired) | _______________ |
| 4. Contracture, left hand | _______________ |
| 5. Osteoarthritis, right shoulder | _______________ |
Systemic Connective Tissue Disorders (M30-M36)
Collagen Diseases
The main component of connective tissue is collagen. Collagen diseases result from immune system malfunctions in which the immune system identifies the body’s connective tissue as foreign and attacks it. A patient’s heart, lungs, and kidneys may also suffer damage. No cure is known for these diseases. The most common conditions include systemic lupus erythematosus, scleroderma, and rheumatoid arthritis.
Systemic lupus erythematosus (SLE) is a chronic, inflammatory autoimmune disease that can damage connective tissue anywhere in the body. It causes inflammation of the skin, joints, nervous system, kidneys, lungs, and other organs. A butterfly rash that spreads from one cheek across the nose to the other cheek is a common symptom (Figure 19-6). Fever, fatigue, weight loss, and joint deformity may also be present.
Scleroderma is a chronic, progressive disease that is characterized by hardening of the skin and scarring of internal organs. No cure is known for scleroderma; treatment is supportive and varies according to the organs that are affected. CREST syndrome is a form of scleroderma that includes the following:
Calcinosis—calcification of the skin
Esophageal dysfunction—such as reflux or difficulty in swallowing
Sclerodactyly—hardening of the skin of the fingers or toes
Telangiectasia—dilatation of tiny blood vessels, particularly of the skin
Polymyalgia Rheumatica
Polymyalgia rheumatica, or PMR, is a syndrome that is characterized by severe aching and stiffness in the neck, shoulder girdle, and pelvic girdle. It is classified as a rheumatic disease, although its origin remains undetermined. It has been closely linked to temporal arteritis.
Exercise 19-3
Assign codes to the following conditions.
| 1. Sicca syndrome | _______________ |
| 2. SLE with nephrotic syndrome | _______________ |
| 3. Mixed connective tissue disease | _______________ |
| 4. Kawasaki disease | _______________ |
| 5. Giant cell arteritis | _______________ |
Deforming Dorsopathies (M40-M43), Spondylopathies (M45-M49), and Other Dorsopathies (M50-M54)
Spinal Deformities
Sometimes, the normal curvatures of the spine are altered. Lordosis is an exaggerated inward curvature of the spine that may be caused by increased abdominal girth due to obesity, pregnancy, or abdominal tumor (Figure 19-7, A). Improved posture, exercise, and weight loss can often alleviate symptoms. Kyphosis is an excessive posterior curvature of the thoracic spine that may not be detected until a hump in the upper back is noticeable (Figure 19-7, B). In older people, particularly women, osteoporosis is often the cause. If it occurs in children or adolescents, the exact cause may have to be determined, so that the best treatment approach can be selected. Scoliosis is a lateral or sideways curvature of the spine (Figure 9-8). School screening programs may detect spinal abnormalities. Varying degrees of abnormality may be observed, and often, conservative medical management is attempted. In severe cases, the performance of procedures that fuse the vertebrae and the application of internal fixation devices such as rods, wires, plates, and/or screws may be necessary to correct the problem.
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