The use of Patient Reported Outcome Measures (PROM) for knee pathology may be affected by socioeconomic factors, language barriers and time constraints in busy outpatient clinics. The Squat and Smile Test (SST) is an example of such a test that has previously been validated for femur fractures. The aim of this study was to validate the SST against other PROM in patients with knee pathology.
Patients presenting to a subspecialist knee clinic in a large hospital in sub-Saharan Africa were approached to participate. They were asked to squat and the depth of the squat as well as the need to support themselves were classified into 4 categories. To describe their pain, participants also selected one of three smiley faces (unhappy, neutral, smiling). These test scores were correlated to the patient’s Knee Injury and Osteoarthritis Outcome Score (KOOS), Lysholm Tegner Score and EQ5D scores.
Seventy patients (median age 53.4 years) were included. The Squat depth correlated moderately with the KOOS score (r = 0.56) and poorly with the EQ5D and Lysholm scores (r=0.46; r= 0.43). The need for squat support had poor correlations with the KOOS, EQ5D and Lysholm scores (r= 0.29; r=0.31; r=0.31) as did the Smiley Face component (r=0.40; r=0.32; r=0.30).
For patients with knee pathology, the squat depth correlates moderately with other PROM. It could therefore be used in settings for which conventional PROM have limited application. Support needed to squat, and a visual analogue scale of smiley faces had poor correlation when compared to other knee PROM and should not be used for the assessment of knee pathology.