International Knee Documentation Committee Rating System

Introduction

To provide a comprehensive analysis of the knee condition and the effect of a treatment protocol on a knee injury or disorder, authors have suggested that rating systems measure a variety of symptoms, sports and daily activity functions, and objective findings. To our knowledge, only three knee-specific rating systems are available that measure all of these factors and have established psychometric properties of reliability, validity and responsiveness: the Cincinnati Knee Rating System (CKRS), the International Knee Documentation Committee (IKDC) Knee Evaluation system, and the new Knee Society Scoring System. The CKRS (see Chapter 41 ) and IKDC Knee Evaluation measure pain, swelling, giving way, functions of sports and daily activities, sports activity levels, patient perception of the knee condition, range of knee motion, joint effusion, tibiofemoral and patellofemoral crepitus, knee ligament subluxations, compartment narrowing on radiographs, and lower limb symmetry during single leg hop tests. The new Knee Society Scoring system (see Chapter 45 ) is designed specifically for arthroplasty research investigations. It includes an objective knee score completed by the physician (measuring alignment, instability, and joint motion) and multiple scales completed by the patient that assess symptoms, satisfaction, and daily and athletic functions and limitations.

The IKDC is one of the most commonly used instruments to determine the results of anterior cruciate ligament (ACL) reconstruction and other knee operations and injuries. This chapter describes the history, development, initial forms, and revisions of the IKDC system. Investigations which provided reliability, validity, and responsiveness data are summarized. The major sections of the current knee forms are described.

History of the IKDC

As early as 1983, some authors expressed concern that comparing results of different methods of treatment of ACL ruptures was not possible without a standardized method of evaluation. At that time, a multitude of scoring systems had been proposed to quantify symptoms and functional limitations caused by ACL injuries and to evaluate the results of operative and conservative treatment. None of these systems were accepted internationally. One major problem was that the majority assigned numerical values to factors that were not quantifiable, weighted certain factors over others, and then added these scores together to provide either an excellent, good, fair, or poor overall outcome grade. Because the content and relative weight given to each component varied greatly from one system to another, individuals rated as excellent or good on one instrument could be rated as fair or poor on another.

To develop a worldwide, standardized knee ligament rating system, a group of knee surgeons from Europe (European Society of Sports Traumatology, Knee Surgery and Arthroscopy [ESKA]) and America (American Orthopaedic Society for Sports Medicine [AOSSM]) founded the IKDC in 1987 ( Table 42-1 ). Common terminology to describe knee motion and function were agreed upon by the committee members. A set of measurements to determine knee motion limits was validated in formal investigations. Methods to quantify knee function, activity levels, and symptoms were evaluated. A single-page Knee Ligament Standard Evaluation Form was then created ( Fig. 42-1 ). The goals of the evaluation form were to measure the essential criteria judged at that time to be necessary to determine the results of treatment and to be simple enough to complete so that research personnel were not required. The committee anticipated that a more comprehensive system would eventually be developed. The form evaluated sports activity levels and eight domains, including patient's assessment of knee function, symptoms, range of knee motion, ligament evaluation, compartment findings, harvest site pathology, radiographic findings, and single-leg hop function testing.

The 1995 IKDC evaluation form adopted the philosophy of Noyes and coworkers (contained in the CKRS ) in the assessment of symptoms that were graded at the highest activity level possible without incurring pain, swelling, or giving way. Two questions determined the patient's assessment of knee function and its effect on activity level. A total of 24 factors were rated as normal, nearly normal, abnormal, or severely abnormal as shown in Figure 42-1 . Four domains (patient's subjective assessment, symptoms, range of motion, and ligament evaluation) received a final rating, and an overall evaluation result was derived, also using the same philosophy as the CKRS. In this manner, the lowest-graded factor determined the overall grade for each individual domain and the final evaluation. For example, a knee that had a positive pivot shift test and 6 mm of increased anteroposterior displacement on KT-2000 testing would receive an abnormal rating, even if all of the other categories were rated as normal or nearly normal. The form also rated sports activities according to a four-level gradient of strenuous, moderate, light, or sedentary.

Irrgang and associates evaluated the construct and concurrent validity of the 1995 IKDC evaluation form in 133 patients who were 1 to 5 years post-ACL reconstruction. These authors reported that the form was useful for reporting outcome after ACL reconstruction. The scoring system clearly distinguished patients whose outcomes were normal or nearly normal from those who were abnormal or severely abnormal, thus preventing a positively biased result when a significant problem in the knee persisted postoperatively. All of the domains contributed to the final rating; however, symptoms and knee ligament evaluation accounted for 62% of the variance in the final rating. The authors did not conduct reliability or responsiveness testing in this investigation.

Paxton and colleagues reported the reliability and internal consistency of the 1995 IKDC evaluation form in 153 patients who had sustained patellar dislocations. The patients completed the form 2 to 5 years after their injury. Adequate reliability and internal consistency (correlation coefficients, 0.82 and 0.84, respectively) were reported. However, high ceiling effects were noted that indicated poor content validity for this group of patients.

Components of the IKDC Knee Scoring System

The IKDC Knee Scoring System currently includes six forms for research investigations. The IKDC is copyrighted by the AOSSM and all of the forms are available on the website of the AOSSM at www.sportsmed.org . The forms have been translated into Portuguese, Chinese, French, German, Greek, Italian, Japanese, Korean, Spanish, and Swedish.

• 1.

  2000 IKDC Subjective Knee Evaluation Form

• 2.

  2000 IKDC Knee Examination Form

• 3.

  IKDC Demographic Form (Musculoskeletal Outcomes Data Evaluation and Management System [MODEMS] demographic form)

• 4.

  IKDC Current Health Assessment Form (Medical Outcomes Study 36-Item Short Form Health Survey [SF-36] form)

• 5.

  2000 IKDC Knee History Form

• 6.

  2000 IKDC Surgical Documentation Form

An online IKDC Scoring worksheet is also available on the website of the AOSSM. The patient's responses to each question are entered and the worksheet calculates a raw (overall) score and a percentile rank (relative to age- and gender-based norms). Also available on this website is the modified IKDC Subjective Knee Form (Pedi-IKDC), developed for children and adolescents who are between 10 and 18 years of age. This form was found to have adequate validity and internal consistency in a group of 673 patients. However, its reliability and responsiveness have not been published.