Development of the Knee Numeric-Entity Evaluation Score (KNEES – ACL): A condition-specific questionnaire J. D. Comins 1,2 , M. R. Krogsgaard 1 , J. Brodersen 2 1 Section for Sports Traumatology, Department of Orthopedic Surgery, Copenhagen University Hospital – Bispebjerg, Copenhagen, Denmark, 2 Research Unit and Section of General Practice, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark Corresponding author: Jonathan D. Comins, PT, MS, PhD, Section for Sports Traumatology, Department of Orthopedic Surgery, Copenhagen University Hospital – Bispebjerg, Bispebjerg Bakke 23, 2400 Copenhagen, NV, Denmark. Tel: +45 35 32 79 60, Fax: +45 35 32 79 46, E-mail: jocom@sund.ku.dk Accepted for publication 28 March 2013 Patient-related outcome measures (PROMs) are com- monly used to gauge treatment effects in patients with anterior cruciate ligament (ACL) deficiency. Valid mea- sures of specific conditions depend on relevant item content. While item content can be derived either from clinicians (face validity) or from patients, item relevance and comprehensiveness can only be confirmed by the patient (content validity). Focus group and single inter- views were conducted with patients’ pre- and post-ACL reconstruction in order to construct a condition-specific PROM for the target patients. One hundred fifty-seven items from a previously conducted literature search were used as a basis for content genesis. Content satu- ration was achieved after three focus groups and seven single interviews. Thirty-eight items from the literature search were directly endorsed, and five modified items were endorsed. Twelve new item themes with verbatim content emerged. Thus, a 55-item pilot PROM consist- ing of six conceptual domains was assembled. We have constructed a condition-specific PROM for measure- ment of surgical and non-surgical treatment effects on ACL deficiency. The instrument possesses face and content validity. A pilot survey to assess the psychomet- ric properties will be performed using Rasch measure- ment theory. Rupture of the anterior cruciate ligament (ACL) is among the most frequent knee injuries in Western civi- lization and significantly affects function and increases the risk of knee osteoarthritis (OA) (Gelber et al., 2000; Lohmander et al., 2007). Nearly one-quarter of all persons with knee OA have an ACL rupture (Hill et al., 2005), and reconstruction of the ACL is one of the most common knee surgeries (Johnson, 1983). Current patient-related outcome measures (PROMs) for patients with ACL deficiency do not register differences in treatment effect when comparing interventions (Johnson, 2011). PROMs are health-related question- naires. Whether PROMs in fact measure the construct needs to be confirmed for meaningful interpretation of treatment results. However, when just 50–70% of ACL- deficient athletes regain pre-operative levels of activity (Krogsgaard, 2002; Johnson, 2011), better treatment results and more sensitive measures are needed. Particu- larly when PROMs are used as clinical endpoints, it is paramount that the instruments are appropriately and sufficiently validated, which is seldom the case (Johnson & Smith, 2001; Krogsgaard, 2005; Johnson, 2011). PROMs used to assess patients with ACL deficiency have historically not been rigorously validated (Zarins, 2005; Hambly & Griva, 2008; Comins et al., 2010). A recent editorial stresses the need for quality longitudinal studies to determine which patients are suitable for ACL surgery (Snyder-Mackler & Risberg, 2011). A basic requirement for conducting longitudinal group compari- sons among groups is that the PROM must be specifi- cally relevant for the targeted patient group (Streiner & Norman, 2008). PROMs are characterized as “any report coming directly from subjects without interpretation of the phy- sician or others about how they function overall or feel in relation to a condition and its therapy” (Patrick et al., 2007). Thus, the objective of PROMs is to measure latent constructs (latent variables) not directly measur- able by the clinician (McKenna et al., 2001; Doward & McKenna, 2004). Rigorous qualitative and quantitative methods are required in order to construct PROMs that can measure clinically important attributes for the tar- geted patient group (Doward & McKenna, 2004; Brodersen et al., 2005b; Patrick et al., 2007; Streiner & Scand J Med Sci Sports 2013: 23: e293–e301 doi: 10.1111/sms.12079 © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd e293