156 Helsinki. All patients gave their consent to participate in this study prior to case review. Between June 2001 and January 2006, we identiﬁed patients who underwent total hip arthroplasties (THA) performed by the senior author. The inclusion criterion was diagnosis of OA secondary to CHD (Crowe’s classiﬁcation type I or II). The exclusion criterion was revision hip surgery. Each patient was asked to answer two questionnaires by phone, the Short-Form 36 (SF-36) and the Western Ontario and MacMaster University Osteoarthritis Index (WOMAC). The SF-36 is a generic measure of QoL with 36 questions. It consists of an eight-scale proﬁle of func- tional health and well-being, as well as psychometrically based physical and mental health summary measures. The SF-36 is often used as point of reference for other tests [2, 3]. Final score is proportional to individual well-being [4, 5]. The WOMAC is a validated instrument designed speciﬁcally for the assessment of lower extremity pain and function. Usually self-administered, the WOMAC assesses pain, disability and joint stiffness in knee and hip osteo- arthritis using a battery of 24 questions. It is useful for the clinical evaluation of disease treatment, speciﬁcally for short-term investigations [6–8]. Final score is proportional to individual disability. The questionnaires were adminstered pre-operatively, and at a minimum of four months after rehabilitation was completed. The questionnaires were scored per their respective operating manuals [9, 10]. All results were compared with the published literature, and SF-36 results were also compared with those of healthy Italian popula- tions aged 45–54 years, corresponding to the study cohort’s mean age [4, 5, 8, 11, 13–18]. The standard deviation (SD) and effect size (a measure of the strength of the difference between two groups) was calculated for each survey item pre- and post-operatively [11]. Each item was also analyzed for normality (Kolmogorov–Smirnov test). The Student t-test was used for paired comparisons when the data was normally Table 1 SF-36 results Scale Physical functioning Role physical Bodily pain General health Vitality Social functioning Role emotional Mental health 123 Pre-operative mean value (SD) 18.55 (17.71) 28.33 (41.20) 23.26 (24.59) 55.19 (23.26) 32.74 (28.78) 43.55 (29.73) 68.82 (40.31) 48.77 (32.26) J Orthopaed Traumatol (2008) 9:155–158 distributed, and the Wilcoxon signed-ranks test for non- parametric data. Signiﬁcance was set at 0.05. Data analysis was carried out using SPSS (Chicago, IL, USA). Results We identiﬁed 40 THAs in 40 consecutive patients per- formed by a single surgeon. Four patients were unavailable for survey completion. Three patients were excluded due to revision surgery, and two patients were excluded as they had not yet completed their rehabilitation. The study group was thus composed of 31 patients. There were 28 females and 3 males, with a mean age at surgery of 51 years (range 33–70). The mean follow-up time was 36 months (range 4– 60). There were 13 patients with a Type I Crowe classiﬁ- cation, and 18 patients with a type II classiﬁcation. All cases utilized a Conus-type stem and a Fitmore-type cup (Zimmer GmbH, Winterthur, Switzerland). Results from the SF-36 are collated in Table 1. Effect sizes of of 0.2, 0.5 and 0.8 indicate small, medium and large differences, respectively. The effect size (ES) for physical functioning was ES = 3.72, ES for bodily pain = 2.45, and ES for role emotional = 0.61. The percentage relative increase ranged from 36 to 356%. All values were statistically signiﬁcant for P \ 0.05. Results from the WOMAC are collated in Table 2. As a reminder, the ﬁnal score is proportional to individual dis- ability, i.e., a patient with less pain/disability should have a lower score. Once again, the ES and percentage relative increase demonstrated statistically signiﬁcant improve- ments between the patients’ pre- and post-operative values. Discussion In this study, 100% of all questionnaire items were obtained, which should be compared with the literature, P value Effect size Post-operative mean value (SD) 84.52 (12.67) 87.10 (24.89) 83.39 (19.67) 81.74 (15.39) 72.10 (17.78) 84.66 (18.17) 93.55 (20.04) 79.35 (14.68) 0.000 0.000 0.000 0.000 0.000 0.000 0.011 0.000 3.72 1.43 2.45 1.14 1.37 1.38 0.61 0.95 % Relative increase 355.47 207.45 258.51 48.11 120.22 94.40 35.93 62.70