Current Concepts in Clinical Research: Anterior Cruciate Ligament Outcome Instruments

QUALITY OF LIFE OUTCOME MEASURE FOR ACL DEFICIENCY (ACL-QOL)

The ACL-QOL Score was developed in 1998 as a disease-specific measure for patients with chronic ACL deficiency.³⁴ This scale consists of 32 separate items in 31 visual analog questions regarding symptoms and physical complaints, work-related concerns, recreational activities and sport participation or competition, lifestyle, and social and emotional health status relating to the knee. The raw score is transformed into a 0- to 100-point scale, with higher scores indicating a better outcome. The scale is valid, reliable, and responsive for patients with ACL insufficiency,^35,36 and is not applicable to other disorders of the knee. We recommend the ACL-QOL questionnaire be used in conjunction with other currently available objective and functional outcome measures.

CINCINNATI KNEE RATING SYSTEM

The Cincinnati Knee Rating System (CKRS) was first described in 1983 and was modified to include occupational activities, athletic activities, symptoms, and functional limitations.^37,38 There are 11 components, measuring symptoms and disability in sports activity, activities of daily living function, occupational rating, as well as sections that measure physical examination, laxity of the knee, and radiographic evidence of degenerative joint disease.³⁹ The measure is scored on a 100-point scale, with higher scores indicating better outcomes. Scores have been shown to be lower as compared with other outcome measures assessing the same clinical condition.^40,41 Barber-Westin and colleagues³⁹ confirmed the reliability, validity, and responsiveness of the CKRS by testing 350 subjects with and without knee ligament injuries. In 2001, Marx⁴² tested the CKRS subjective form for reliability, validity, and responsiveness and found it to be acceptable for clinical research.

LYSHOLM KNEE SCORE

The Lysholm Knee Score was published in 1982 and modified in 1985, consisting of an 8-question survey that evaluates outcomes after knee ligament surgery. Items include pain, instability, locking, squatting, limping, support usage, swelling, and stair-climbing ability, with pain and instability carrying the highest weight.⁴³ It is scored on a scale of 0 to 100, with high scores indicating higher functioning and fewer symptoms. It has been validated in patients with ACL injuries and meniscal injuries.⁴⁴ Although it is widely used to measure outcomes after ACL reconstruction,⁴⁵ it has received criticism in the evaluation of patients with other knee conditions.⁴⁶ The main advantage of the Lysholm Knee Score is its ability to note changes in activity in the same patient across different time periods (responsiveness). A limitation of the Lysholm Knee Score is that it does not measure the domains of functioning in daily activities, sports, and recreational activities. The Lysholm scoring system’s test-retest reliability and construct validity have been evaluated,^42,43,46 although there has been some concern regarding a ceiling effect and its validity, sensitivity, and reliability has been questioned.⁴⁷ Therefore, it is advised that this score be used in conjunction with other PRO scores.

INTERNATIONAL KNEE DOCUMENTATION COMMITTEE (IKDC) SUBJECTIVE KNEE FORM

In 1987, members of the European Society for Knee Surgery and Arthroscopy and the American Orthopaedic Society for Sports Medicine formed the IKDC to develop a standardized method for evaluating knee injuries and treatment. The IKDC Subjective Knee Evaluation Form was initially published in 1993, and in 2001 the form was revised by the American Orthopaedic Society for Sports Medicine to become a knee-specific assessment tool rather than a disease or condition-specific tool.⁴⁸ The IKDC subjective form is an 18-question, knee-specific survey designed to detect improvement or deterioration in symptoms, function, and ability to participate in sports activities experienced by patients following knee surgery or other interventions. The individual items are summed and transformed into a 0- to 100-point scale, with high scores representing higher levels of function and minimal symptoms. The IKDC is utilized to assess a variety of knee conditions including ligament, meniscus, articular cartilage, osteoarthritis, and patellofemoral pain.^48,49 Thus, this form can be used to assess any condition involving the knee and allow comparison between groups with different diagnoses. The IKDC has been validated for an ACL reconstruction population,⁴⁷ has been used to assess outcomes in recent clinical studies on ACL reconstruction,^50,51 and is one of the most frequently used measures for patients with ACL deficiency.³ The validity, responsiveness, and reliability of the IKDC subjective form has been confirmed for both adult and adolescent populations.^48,49,52-54

TEGNER ACTIVITY SCORES

The Tegner activity score was developed in 1985 and was designed to provide an objective value for a patient’s activity level.⁴⁴ This scale was developed to complement the Lysholm score. It consists of 1 sport-specific activity level question on a 0 to 10 scale that evaluates an individual’s ability to compete in a sporting activity. Scores between 1 and 5 represent work or recreational sports. Scores >5 represent higher-level recreational and competitive sports. The Tegner activity score is one of the most widely used activity scoring systems for patients with knee disorders,^55,56 commonly utilized with the Lysholm Knee Score.⁴⁴ One disadvantage of the Tegner activity score is that it relates to specific sports rather than functional activities, which limits its generalizability. We are not aware of any studies documenting the reliability or validity of this instrument.

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