Reviewed by Jerome Thomas, SPT, Tyler Tice, PT, DPT, OCS, ATC

Utilization of total knee arthroplasty (TKA) procedures in the United States has skyrocketed in recent years. According to Cram et. al (2012), the annual volume of TKA surgeries among Medicare beneficiaries increased 161.5% between 1991 and 2010. In this research article, Cram and his colleagues proposed that this dramatic advancement in TKA surgeries could be due to the fact that the TKA procedure is highly reliant on subjective criteria, therefore lending itself to potential over-utilization. Determining whether a TKA surgery is advisable for a patient requires evidence-based appropriateness criteria; however, these specific criteria have never formally been developed for patients undergoing TKAs. The aim of this cohort study is to determine if the current TKA appropriateness criteria is valid and accurately predicts whether a patient should opt for a TKA surgery.

As previously mentioned, there has been no formal appropriateness criteria for TKA procedures in the United States. The most commonly recommended and studied approach is the RAND/UCLA method developed by Escobar and his colleagues in Spain. Escobar et. al constructed their TKA appropriateness algorithm based on several variables: symptom behavior, age, extent of radiographic arthritis, prior medical history, knee joint mobility and stability, and functional status. These researchers in Spain then tested their algorithm against 775 TKA patients and determined their appropriateness based on their specialized criterion. The purpose of this cohort study was to modify Escobar’s system for US TKA patients and analyze its validity in determining whether a patient is a good candidate for a TKA procedure.

For the cohort study, 216 subject data sets were derived from 4,796 possible patients enrolled in the Osteoarthritis Initiative (OAI). In order to assess severity of knee arthritis for each patient, the KL radiographic grading system was utilized: 1 indicated mild (1 to 33%) narrowing, 2 indicated moderate (34–66%) narrowing and 3 indicated severe (67 to 100%) narrowing. The WOMAC Physical Function scale evaluates the functional status of each patient and how their symptoms impact their function:0 = none, 1=mild impairment, 2= moderate impairment, 3=severe impairment, 4=extreme impairment. Additionally, patients were categorized as limited when they had either less than 0° to 90° of knee motion or greater than 5 millimeters of medial or lateral gapping during stress testing.

The results of the cohort study were based on the modifications of Escobar’s appropriateness algorithm. Of 175 subjects with complete data sets, 77 were classified as appropriate TKA surgeries. The majority of patients that were deemed appropriate for TKA surgeries had intense or severe symptoms that impacted functional status, KL arthritis scores of 4 (severe knee joint narrowing), and were greater than 55 years of age. Many patients struggle with the ultimate decision of undergoing a TKA surgery so the researchers of this cohort study wanted to provide evidence-based criteria for patients to aid in their choice.

Clinical Application:

The patient population that are most likely to be deemed appropriate for TKA surgeries are those with intense/severe symptoms that impact functional status, KL arthritis scores of 4 (severe knee joint narrowing shown on radiographic images), and greater than 55 years of age. Other important variables that must be considered before a TKA procedure include psychological readiness for the surgery and the recommendations of all members of the patient’s healthcare team.


Cram P, Lu X, Kates SL, Singh JA, Li Y, Wolf BR. Total knee arthroplasty volume, utilization, and outcomes among Medicare beneficiaries, 1991–2010. JAMA. 2012; 308(12):1227–36.

Escobar A, Quintana JM, Arostegui I, Azkarate J, Guenaga JI, Arenaza JC, et al. Development of explicit criteria for total knee replacement. Int J Technol Assess Health Care. 2003; 19(1):57–70.

Riddle DL, Jiranek WA, Hayes CW. Use of a validated algorithm to judge the appropriateness of total knee arthroplasty in the United States: a multicenter longitudinal cohort study. Arthritis Rheumatol. 2014;66(8):2134-2143.