Background: Self-reported knee complaints may vary with age and gender. Reference data from the adult population would help to better interpret the outcome of interventions due to knee complaints. The objectives of the present study were to describe the variation of self-reported knee pain, function and quality of life with age and gender in the adult population and to establish population-based reference data for the Knee injury and Osteoarthritis Outcome Score (KOOS).

Objective. To evaluate the association between radiographic hand osteoarthritis (OA), a disease with marked heredity, and radiographic knee OA in patients treated with meniscectomy.Methods. We retrospectively identified 170 patients (mean age 54 years [range 33-87 years], 23% women) who had undergone isolated meniscectomy an average of 20 years earlier (range 17-22 years). Patients with cruciate ligament injury were excluded. All subjects were examined by standardized knee and hand radiography. Individual joints were considered to have OA when displaying radiographic features corresponding to a Kellgren/Lawrence (K/L) grade >2. Hand OA was considered present if at least 1 of the following criteria was fulfilled: the presence of radiographic OA (K/L grade >2) in at least 1 interphalangeal joint in each hand symmetrically, or in at least 2 distal or proximal interphalangeal joints in the same hand in a pattern consistent with primary OA (in the same row or ray), or in the first carpometacarpal joint bilaterally. The association between radiographic hand OA and radiographic knee OA was evaluated using logistic regression.Results. Radiographic hand OA was present in 57 patients (34%) and radiographic knee OA was identified in 105 patients (62%), within 94 index knees (55%) and 47 contralateral knees (28%). In a multivariate model, radiographic hand OA was associated with an increased likelihood of radiographic OA in the index knee (odds ratio [OR] 3.0, 95% confidence interval [95% CI] 1.2-7.5) and in the nonoperated contralateral knee (OR 3.5, 95% CI 1.0-12.2).Conclusion. The presence of radiographic hand OA is associated with an increased frequency of radiographic knee OA after meniscectomy. This finding confirms and extends that of a single previous study showing an interaction between hereditary and environmental risk factors for OA, a common and genetically complex disease. Accordingly, the development of OA following a meniscal tear and the resulting meniscal surgery should not be regarded to be of secondary origin only.

ObjectiveTo test the clinimetric properties and to evaluate the internal consistency, validity and reliability of the Polish version of the Knee injury and Osteoarthritis Outcome Score (KOOS) in older patients with end-stage knee osteoarthritis undergoing total knee replacement (TKR).Design and settingA prospective cohort study performed at the university hospital and the outpatient clinic.MethodsThe patients were asked to complete the KOOS questionnaire and the Short Form 36 Health Survey. We evaluated floor/ceiling effects, reliability (using Cronbach's α, intraclass correlation coefficients (ICC) and measurement error), structural validity (performing exploratory principal factor analysis), construct validity (with the use of 3 a priori hypotheses) and responsiveness (using data obtained before and after the surgery, and described by Global Perceived Effect, effect size and standardised response mean).ResultsThe study consisted of 68 participants (mean age 68.8, 82% women). The floor effects were found prior to surgery for the subscales Sports and Recreation Function, and Quality of Life. The Cronbach's α was from 0.90 to 0.92 for all subscales, indicating excellent internal consistency. The test–retest reliability at follow-up was excellent, with ICCs ranging from 0.81 to 0.86 for all KOOS subscales. The minimal detectable change ranged from 18.2 to 24.3 on an individual level and from 2.4 to 2.9 on a group level. All KOOS items were relevant, and all a priori established hypotheses were supported. Responsiveness was confirmed with a statistically significant correlation between all KOOS subscales and the Global Perceived Effect score (ranging from 0.56 to 0.70, p<0.001).ConclusionsThe Polish version of KOOS demonstrated good reliability, validity and responsiveness for use in patient groups that had undergone TKR. Since the smallest change considered clinically relevant cannot reliably be detected in individual cases, the Polish version of KOOS is advocated for assessment of groups of patients.