The ability to vary femoral offset and neck angles in total hip arthroplasty increases the amount of flexibility in the mechanical reconstruction of the hip joint. The present study investigates the changes in strain pattern and bone-implant micromotion caused by increased femoral offset in combination with retroversion or reduced neck-shaft angle, made possible by a large experimental femoral head. A cementless femoral stem was inserted in 10 human cadaver femurs. Three femoral head configurations were tested: the standard situation, an increased offset combined with retroversion, and increased offset combined with reduced neck-shaft angle. The femurs were loaded in a hip simulator that was able to reproduce the conditions that correspond to one-legged stance and stair climbing. There was a statistically significant increase in strain for the experimental head at several strain gauge rosettes compared to the standard head. The largest significant increase in strain was 14.2 per cent on the anterior side of the femur. The largest mean total point motion was 44 microm in the distal coating area for the configuration with increased femoral offset and retroverted neck axis. The clinical relevance of the changes in strain distribution is uncertain. The femoral stem showed excellent initial stability for all test situations.

IntroductionThe current evidence on the efficacy of antibiotic-loaded bone cement (ALBC) in reducing the risk of periprosthetic joint infections (PJI) after primary joint reconstruction is insufficient. In several European countries, the use of ALBC is routine practice unlike in the USA where ALBC use is not approved in low-risk patients. Therefore, we designed a double-blinded pragmatic multicentre register-based randomised controlled non-inferiority trial to investigate the effects of ALBC compared with plain bone cement in primary total knee arthroplasty (TKA).Methods and analysisA minimum of 9,172 patients undergoing full-cemented primary TKA will be recruited and equally randomised into the ALBC group and the plain bone cement group. This trial will be conducted in Norwegian hospitals that routinely perform cemented primary TKA. The primary outcome will be risk of revision surgery due to PJI at 1-year of follow-up. Secondary outcomes will be: risk of revision due to any reason including aseptic loosening at 1, 6, 10 and 20 years of follow-up; patient-related outcome measures like function, pain, satisfaction and health-related quality of life at 1, 6 and 10 years of follow-up; risk of changes in the microbial pattern and resistance profiles of organisms cultured in subsequent revisions at 1, 6, 10 and 20 years of follow-up; cost-effectiveness of routine ALBC versus plain bone cement use in primary TKA. We will use 1:1 randomisation with random permuted blocks and stratify by participating hospitals to randomise patients to receive ALBC or plain bone cement. Inclusion, randomisation and follow-up will be through the Norwegian Arthroplasty Register.Ethics and disseminationThe trial was approved by the Western Norway Regional Committees on Medical and Health Research Ethics (reference number: 2019/751/REK vest) on 21 June 2019. The findings of this trial will be disseminated through peer-reviewed publications and conference presentations.Trial registration numberNCT04135170.

Background Fast-track hip and knee arthroplasty (HA and KA) has been increasingly common over the last decade. In the same time period, there was a strong trend toward less restrictive mobilization. However, few reports have been published on combining these novel programs while measuring the postoperative results by patient-reported outcome measures (PROMs). Descriptions of fast-track surgery programs and their results are warranted. Methods The aim of this retrospective cohort study was to examine if it is possible to achieve excellent PROM results for hip and knee arthroplasty patients in a fast-track pathway without postoperative restrictions. During 2014–2017, the stepwise introduction of a PROM program was implemented at Stavanger University Hospital for all scheduled HA and KA patients, with preoperative assessments and postoperative follow-ups at the outpatient clinic. Standardized information with a focus on early mobilization and no postoperative restrictions was also initiated for the same patients. The generic EuroQol questionnaire (EQ-5D) and either the Hip or Knee disability/injury and Osteoarthritis Outcome Score (HOOS or KOOS) were used. Results PROM response rates varied from 80 to 99%. The median (interquartile range) change from preoperative to one-year postoperative results were as follows for HA and KA patients, respectively: pain, 55 (43–68) and 47 (31–61); other symptoms, 50 (40–65) and 36 (19–50); function in daily living, 54 (41–65) and 44 (31–55); function in sports and recreation, 56 (38–75) and 40 (15–64); joint-related quality of life, 69 (50–81) and 56 (38–75). The length of stay (LOS) was reduced by 1.9 days (mean), corresponding to a 40% reduction for HA patients and a 37% reduction for KA patients. Conclusions We found excellent PROM results after fast-track HA and KA with no postoperative restrictions. We believe that a fast-track program focusing on mobilization without any postoperative restrictions is superior for most patients, but further comparative studies are warranted.