Background and Objectives: Pain is one of the most important outcome variables in epidemiologic studies of musculoskeletal disorders and is most commonly assessed retrospectively. This study examined the reliability/validity of retrospective pain ratings.

Methods: 400 individuals reporting low back pain (LBP) in a population-based survey were invited to participate in a year-long study of the course of LBP. At the start and end, they completed a questionnaire (demographics, symptoms, function, Chronic Pain Grade Questionnaire (CPGQ)). Each week, they completed a one-page diary (numeric rating scale for pain intensity, work limitations and social limitations due to LBP). Participants could choose between electronic or paper versions. Intraclass correlation coefficients indicated the agreement between the weekly ratings and the corresponding retrospective assessment (CPGQ).

Results: 348 individuals agreed to participate; 250 provided complete data-sets. Agreement between prospective and retrospective assessments was good (ICC pain=0.73, 95%CI 0.65–0.79; ICC work limitations=0.82, 95%CI 0.77–0.86; ICC social limitations=0.78, 95%CI 0.71–0.83). Separate analyses revealed no influence on the ICCs of completion-method, age and sex, but an influence of pain severity (severe: ICCs = 0.73, 0.88, 0.82, respectively; mild/moderate: 0.19, 0.22, 0.37, respectively) and pain duration (acute: 0.75, 0.81, 0.79, respectively; sub-acute/chronic: 0.52, 0.77, 0.57, respectively).

Conclusion: The results have important implications for clinical practice and epidemiological studies. For clinical practice, where patients with pain are being treated, retrospective pain assessments up to 6 months seem to be reliable. However, this is not the case in epidemiological studies in which many individuals with no or only moderate pain are involved.

Introduction: Randomized Controlled Trials (RCT) are the golden standard in nowadays evidence based outcome assessment. Nevertheless, RCTs in surgery are associated with several concerns. The major concern focuses on ethical issues when randomization is done.

Method: We conducted an indebt analysis on advantages and disadvantages of three types of data acquisition (Case Control Study (CCS), RCT, and Registries) where scientific impact, ability to assess changes over time, cost efficiency, time consumption, ability to provide bench marks and other variables are compared.

Results: RCTs are best regarding the scientific impact. Registers are superior in detecting changes over time (post market surveillance, early warning system), cost efficiency, time consumption, ability to provide benchmarks, local/national/international comparability and ability to let private practitioners participate. CCSs are of minor value in respect to all the assessed variables.

Conclusion: In Surgery, registries are an excellent alternative to RCTs if a great majority of the treating physicians (in respect to a therapy) participate and if all the treated patients (per physician) are included. The register increases its scientific impact if alternative therapies are included (control). In this case, the scientific impact of a register is getting nearly equivalent to RCTs.

Take home message: If ethical aspects allow an RCT, than the RCT is the study set up of choice when a new technique/implant has to be introduced in the market. Once the implant has proved its evidence, the following post market surveillance should be accompanied by registries (introduction of an implant in each country). If an RCT is not indicated (ethical or other contra indications), than registries should be used to prove evidence for an indicated therapy. CCSs are not recommended.

Aims: The study was carried out to describe the long-term development of relevant clinical parameters after total hip arthroplasty (THA). Methods: Primary and follow-up data from 26‘019 THA from 9‘801 men and 11‘144 women were monitored across a postoperative period of 15 years. The population was described as one group and according to Charnley. Results: Patients experienced significant pain relief and major improvements in mobility and hip motion. The 5% of patients with preoperatively no or mild hip pain grew to 90–95% postoperatively and was 85% 15 years later. The 8% patients with a preoperatively free walking time greater 30 min. increased to 60% postoperatively. 15 years after the THA 60% managed free walking times up to 30 minutes. A hip flexion greater 90 degrees was preoperatively possible for 22% of the patients, postoperatively for 78%. Up to 94% judged the outcome as excellent or good after one year and 84% after fifteen years. The prevalence of radiographically loose stems increased from 0.87% to 14.44% 14 years postoperatively. Simultaneously, the prevalence of radiographically loose cups increased from 0.8% to 16.67%. Conclusions: A THA delivers significant gain in mobility, hip motion and pain relief and a high number of satisfied patients. A constant deterioration of abilities and satisfaction could be observed beginning three to five years after the primary operation. However, 15 years postoperatively, these abilities were still superior to the preoperative levels. A steady increase in radiographically loose components was noted. It took patients three to five years to reach their maximum outcome.

Aims: New threshold levels for a classification of Harris hip score (HHS) with respect to patient satisfaction after total hip arthroplasty (THA) were calculated. Methods: Registry data from four follow-up intervals (< =3, 3–6, 6–9, > 9 years) from 3824 female and 4002 male patients were analyzed and optimal agreements between patient satisfaction and HHS classes were calculated using kappa values (κ). Patients were classified into Charnley classes A and B/C. HHS outcome was transformed into a binary format (positive, negative). Results: Associations between outcomes of the complete patient group using the normal HHS-classification (100, 90, 80,< 70) were weak (κ≤ 0.42). For a binary outcome classification with positive (excellent, good) and negative (fair, poor) results, associations improved especially for Charnley A patients (κ=0.46). Using the recalibrated HHS, the separation of patients in Charnley A vs. B/C and a binary outcome classification resulted in clear associations between HHS results and patient evaluation in both groups A (κ=0.527) and B/C (κ=0.424). The new thresholds were 95 (good), 75 (fair) and 65 (poor) for Charnley A and 95, 75 and 60 for Charnley B/C respectively. Conclusions: The newly calibrated HHS can differentiate between a patient perceived positive and a negative outcome in Charnley A and B/C patients. The differentiation between these two groups is essential since Charnley B and C patients have, by definition, an inferior mobility compared to Charnley A patients which can render a successful THA as fair and poor in many of those patients if the traditional HHS classification is applied.