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Current Concepts in Clinical Research: Anterior Cruciate Ligament Outcome Instruments

May 4, 2018 | Surgery
Molly Day, MD, ATC ; Kyle Hancock, MD ; Natalie Glass, PhD ; Matthew Bollier, MD
Author and Disclosure Information

Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article.

Dr. Day and Dr. Hancock are Orthopedic Surgery Residents; Dr. Glass is a Statistician; and Dr. Bollier is Congdon Professor in Orthopedic Surgery, Sports Medicine Fellowship Director, and Team Physician, Department of Orthopedics and Rehabilitation, University of Iowa Hospitals and Clinics, Iowa City, Iowa.

Address correspondence to: Matthew J. Bollier, MD, University of Iowa Hospitals and Clinics, Department of Orthopedics and Rehabilitation, 200 Hawkins Drive, Iowa City, IA 52242 (tel, 319-467-8324; fax, 319-356-8999; email, matthew-bollier@uiowa.edu).

Am J Orthop. 2018;47(5). Copyright Frontline Medical Communications Inc. 2018. All rights reserved.

Molly Day, MD, ATC Kyle Hancock, MD Natalie Glass, PhD Matthew Bollier, MD . Current Concepts in Clinical Research: Anterior Cruciate Ligament Outcome Instruments. Am J Orthop.

May 4, 2018

TAKE-HOME POINTS

  • PRO instruments are widely used to capture patient perception of general health, QOL, daily function, and pain, and are an essential part of evaluation after ACL reconstruction.
  • ACL outcome measures vary widely in regards to their validity, reliability, minimal clinically important difference, and applicability to specific patient populations.
  • There is currently no standardized instrument universally accepted as superior following ACL reconstruction.
  • In most cases, a general health outcome measure should be used in combination with a condition-specific rating scale.
  • Activity rating scales, such as Marx or Tegner, should be included when evaluating patients with low-activity lifestyles.

MARX ACTIVITY RATING SCALE

The Marx activity rating scale was developed to be utilized with other knee rating scales and outcome measures as an activity assessment.57 In contrast to the Tegner activity score, the Marx activity rating scale measures function rather than sport-specific activity. The scale is a short, patient-based activity assessment that consists of a 4-question survey evaluating patients’ knee health by recording the frequency and intensity of participation in a sporting activity. Questions are scored from 0 to 4 on the basis of how often the activity is performed. The 4 sections of the Marx scale that are rated include running, cutting, decelerating, and pivoting. This scale has been validated in patients with ACL injuries, chondromalacia patellae, and meniscal lesions.42,56-58 Acceptable ceiling effects of 3% and floor effects of 8% were noted in the study of ACL-injured patients.57

AMERICAN ACADEMY OF ORTHOPAEDIC SURGEONS (AAOS) SPORTS KNEE SCALE

The American Academy of Orthopaedic Surgeons (AAOS) Sports Knee Rating Scale consists of 5 parts and 23 items, including a section addressing stiffness, swelling, pain and function (7 questions), locking/catching (4 questions), giving way (4 questions), limitations of activity (4 questions), and pain with activity (4 questions).59,60 Items may be dropped if patients select particular responses, which can lead to difficulties when using the survey. This scoring system has been found to be satisfactory when all subscales were combined and the mean was calculated.42

DISCUSSION

PRO measures play an increasingly important role in the measurement of success and impact of health care services. Specifically, for ACL reconstruction, patient satisfaction is key for demonstrating the value of operative or other interventions. Selecting a suitable outcome measurement tool can be daunting, as it can be difficult to ascertain which outcome measures are appropriate for the patient or disorder in question. As there is currently no instrument that is universally superior in the evaluation of ACL outcomes, clinicians must consider the specific patient population in which the outcome instrument has been evaluated. Investigators should also use instruments with reported minimal clinically important differences so that variation in scores can be interpreted as either clinically significant or not. When choosing which outcome instrument to use, there is rarely a single appropriate rating system that is entirely comprehensive. In most cases, a general health outcome measure should be used in combination with a condition-specific rating scale. Activity rating scales, such as Marx or Tegner, should be included, especially when evaluating patients with low-activity lifestyles.

CONCLUSION

There are a number of reliable, valid, and responsive outcome measures that can be utilized to evaluate outcomes following ACL reconstruction in an array of patient populations. Outcome measures should be relevant to patients, easy to use, reliable, valid, and responsive to change. By increasing familiarity with these outcome measures, orthopedic surgeons and investigators can develop better studies, interpret data, and implement findings in practice with sound and informed judgment. Future research should focus on identifying the most relevant outcome metrics for assessing function following ACL reconstruction.

This paper will be judged for the Resident Writer’s Award.

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