The Ins and Outs of Joint Replacement Coding

By: ADVANCE Staff

Total joint replacement (TJR) and, more specifically, total knee or total hip replacement procedures have become two of the most commonly performed and successful procedures in medicine today. The hospital discharge rate for total hip replacement increased by one-third, and the discharge rate for knee replacement increased by 70 percent from 1996 to 2006. Several factors have contributed to the explosive growth of these services. The overall population is aging, but many of the “senior” members of society are more active and are requesting these procedures at younger ages than their parents’ generation did. Add this to clinical factors related to implant longevity and the need for increased TJR services is clear to see.

To fully understand the codes associated with the diagnoses related to TJR, it’s helpful to understand the background and causes. The vast majority of TJR patients suffer from arthritis, which is the second most common chronic disease in the U.S. today. Although most commonly associated with the elderly and 20-30 percent of people over the age of 70 suffer from osteoarthritis of the hip, the disease also affects 50 million (22 percent) adults throughout the country.

Total costs associate with arthritis amount to more than $82 billion, which includes drug and hospital costs, nursing home costs and lost productivity. And while non-operative treatment options are typically attempted before moving to a surgical treatment option, for many people the non-operative solutions are only temporary and do not offer a long-term solution.

Non-operative options include activity modification, weight loss, physical therapy, drug injections or other medication regimens. After these options have been exhausted the patient may be offered a surgical treatment option, which may include a joint preserving procedure (such as arthroscopy, osteotomy or cartilage transplantation) or arthroplasty. The arthroplasty methods include hemi-arthroplasty (partial joint replacement), a resurfacing arthroplasty or the total joint replacement option.

Coding staff don’t generally have trouble assigning diagnosis codes for patients with arthritis undergoing initial joint replacement. But as younger and more active patients begin having problems over time with their prostheses, the codes describing these joint replacement complications have become much more specific. Causes of TJR failure may be varied and can include:

  • Mechanical loosening

  • Articular bearing surface wear

  • Infection

  • Instability

  • Osteolysis

  • Peri-prosthetic fracture

  • Implant failure

A small proportion (< 10 percent) of TJR complications occur within the first 5 years, which is considered an “early” complication. These typically involve dislocation, infection or an implant failure. The majority of TJR complications occur after the first 5 years and may involve mechanical loosening, peri-prosthetic fracture, osteolysis or wear of the articular bearing surface, which increases over time. When the articular bearing surface wear has progressed to a point where the prosthesis has loosened or the patient experiences significant pain, a revision of the TJR is usually recommended.

When a fracture of a prosthetic joint is due to trauma, it should be coded to a traumatic fracture code with the appropriate V-code from category V43.6 (Joint replacement status), to indicate the specific joint involved. If a pathologic fracture of a prosthetic joint is documented as due to an underlying condition (such as osteoporosis or a neoplasm), the case should be coded as a pathologic fracture, and again, the appropriate code from the V43.6 category should be added as a secondary diagnosis. Infections of a prosthetic joint are assigned to code 996.66 (Infection and inflammatory reaction due to internal joint prosthesis). In some cases, the only complication documented may be pain, which is assigned to code 996.77 (Other complications due to internal joint prosthesis).

Specific Diagnosis Codes
There are currently several subcategories of diagnosis codes that provide significant specificity in the type of TJR mechanical complication documented. When these codes are assigned, an instructional note indicates: “Use additional code to identify prosthetic joint with mechanical complication (V43.60 – V43.69).” The first of these codes is the most non-specific, describes an “unspecified mechanical complication” and should be avoided if possible. If the medical record does not indicate the complication involved, the physician should be queried for more information. This range of codes is as follows:

996.40 Unspecified mechanical complication of internal orthopedic device, implant or graft

996.41 Mechanical loosening of prosthetic joint

Aseptic loosening

    1. Dislocation of prosthetic joint

      2. Instability of prosthetic joint

      Subluxation of prosthetic joint

    2. Broken prosthetic joint implant

      3. Breakage (fracture) of prosthetic joint

    3. Peri-prosthetic fracture around prosthetic joint

    4. Peri-prosthetic osteolysis

    5. Articular bearing surface wear of prosthetic joint

    6. Other mechanical complication of prosthetic joint implant

Mechanical complication of prosthetic joint NOS

Prosthetic joint implant failure NOS

996.49 Other mechanical complication of other internal orthopedic device, implant, and graft

Breakage of internal fixation device in bone

Dislocation of internal fixation device in bone

Coders should keep in mind that although these codes are included within the complication section of the ICD-9-CM, their use does not always indicate poor medical care or faulty devices. All devices wear out over time and the codes in this subcategory are for use regardless of the age of the prosthetic joint. It’s also important to determine the site of breakage when documentation indicates a TJR breakage. If the breakage involves the device itself, it should be coded to 996.43, but if the breakage involves physiological sites such as the bone around the device, it should be coded to 996.44. Peri-prosthetic osteolysis is unwanted destruction of bone that occurs when the body mounts a cellular reaction to bone wear debris due to TJR. It should be coded to 996.45.

The type and cause of the joint replacement failure will determine the type of revision joint replacement procedure and the diagnosis and procedure codes should match. Coding staff should ensure that if a code for a specific type of TJR failure is present, that the revision procedure matches that diagnosis. In addition, a fracture of a prosthetic joint due to trauma should be coded to a traumatic fracture code with the appropriate V code from subcategory V43.6, Joint replaced by other means, to indicate the joint prosthesis status. A pathologic fracture of a prosthetic joint due to an underlying condition, such as osteoporosis or a neoplasm, should be coded as a pathologic fracture, also with the appropriate V43.6 code. The Coding Clinic issue from 4th quarter 2005 contains an article detailing code assignment for complication of total join replacements.

After review of the article, test your knowledge with the quiz below:

Questions:

    1. A 72-year-old male had previously undergone total hip replacement. He now returns with a loosened acetabular component that is causing significant pain. The patient was admitted and taken to the operating room for a procedure that included removal and replacement of the acetabular component only, using a metal-on-polyethylene bearing surface. The appropriate diagnosis codes are:

      1. 996.4, V43.64

      2. 996.77, V43.64

      3. 996.66, V43.6

      4. 996.41, V43.64

    2. A 69-year-old woman has had significant problems with infections since her previously total hip replacement. She is now admitted for revision of the joint prosthesis, which included combined components, ceramic-on-ceramic implant bearing surface and removal of previously placed cement spacers. The appropriate diagnosis codes are:

      1. 996.77, V43.65

      2. 996.66, V43.64

      3. 996.41, V43.64

      4. 996.41, V43.65

    3. A 67-year-old male patient had a previously placed knee joint prosthesis and now returns with a peri-prosthetic fracture. No trauma was documented. Surgery included replacement of the femoral and tibial components. The appropriate diagnosis codes are:

      1. 996.44, V43.65

      2. 996.43, V43.65

      3. 996.44, V43.64

      4. 996.47, V43.65

Answers:

    1. d. The diagnosis code 996.41 (fifth digit required) indicates a loosening of the prosthetic joint and the V-code indicating hip replacement status also requires a fifth digit.
    2. b. The principal diagnosis is infection of the joint prosthesis (996.66), and the joint previously replaced and being treated on this admission involved the hip (V43.64).
    3. a. Since the problem with the joint prosthesis involved a peri-prosthetic fracture, assign code 996.44 as the principal diagnosis. The V43.65 code appropriately reflects a knee replacement status.

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