Document Articular Cartilage Damage When Rating Impairment of the Knee

Saturday, September 22, 2007 | 0

By Dr. Craig M. Uejo

This is the next article in a series written to assist evaluators in their use and interpretation of The AMA Guides to the Evaluation of Permanent Impairment, Fifth Edition (Cocchiarella L, Anderson G, AMA Guides to the Evaluation of Permanent Impairment, Fifth Edition, AMA Press, 2001).

It will be used to help summarize key points of clarification documented in past issues of The Guides Newsletter. References to specific issues will be provided to allow anyone the opportunity to review the entire issue/article for assistance in understanding and accuracy of reporting.

This particular article will discuss the issues of rating a full thickness knee articular cartilage injury or ununited osteochondral fracture in the case where radiographic cartilage interval measurements are "normal." This issue was discussed in the March/April 2005 edition of The Guides Newsletter - Knee Arthritis. Christopher Brigham, MD; Charles Brooks, MD; and James Talmage, MD were the authors.

Knee - Osteochondral Fracture or Full-Thickness Chondral Defect with Normal Joint Space Measurements

Knee contusion injuries can result in articular cartilage injuries such as full-thickness chondral defects or small ununited osteochondral fractures without documentable impairment based on the methodologies outlined in the Guides, 5th ed. Namely, there can be no motion loss, instability, strength loss, neurological deficits, etc. Arthritis can be a ratable finding if on radiographs there is documented joint space narrowing equal to or less than 3mm. If, however, there are normal joint spaces, the question raised by some evaluators is "could there be ratable impairment absent these methodologies?"

The Guides Newsletter article documents the following argument; Yes, there could be 7% lower extremity or 3% whole person impairment similar to a case of knee osteoarthritis with "mild" joint space narrowing:

The last sentence of text pertaining to diagnosis-based estimates states, "A diagnosis of full thickness chondral defect or ununited osteochondral fracture requires arthroscopic or surgical confirmation" (5th ed, 549). As implied in an article titled "Challenges with Chapter 17, The Lower Extremities 21" and in the Question and Answer section of The Guides Newsletter November-December 2003 issue, the Committee for the Lower Extremities had proposed changes to Table 17-33, Impairment Estimates for Certain Lower Extremity Impairments (5th ed, 546- 547), that would have resulted in impairment ratings for these conditions being listed. The rating for a full thickness chondral defect or ununited osteochondral fracture with a normal cartilage interval would be the same as that for mild arthritis in Table 17-31, Arthritis Impairments Based on Roentgenographically Determined Cartilage Intervals (5th ed, 544). For the knee, either of these conditions would result in 3% whole person or 7% lower extremity impairment.

In summary:

The Guides 5th ed. recommends considering rating a knee injury that resulted in documentable articular cartilage damage with a full-thickness chondral defect or an ununited osteochondral fracture and normal joint space measurements with 7% lower extremity or 3% whole person impairment.

Uejo is a CIR Medical Director at Brigham and Associates Inc. To view more of these tips visit:

www.impairment.com/tips

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