In patients complaining of recurrent patellar dislocations or persistent retropatellar pain due to a dysplastic femoral trochlea, we perform a Henri Dejour trochleoplasty. In this technique the femoral trochlea is deepened by removing the subchondral trochlear bone followed by incision, impaction and fixation of the cartilage flange along the trochlear groove. Between 1996 and 1999, 13 procedures were performed in 12 patients. Strictly lateral X-rays showed dysplasia of the trochlea, as defined by the "crossing sign", whether or not in combination with patella alta. Patients were assessed using the Larsen-Lauridsen score considering pain, stiffness, osteopatellar crepitus, flexion and loss of function. Although the majority of patients scored fair and poor on an objective scoring system, we achieved 77% good to very good subjective results. Although the result was not perfect, the patients were satisfied with the procedure. This technique might be a valuable alternative in cases of frank trochlear dysplasia associated with persistent retropatellar pain or recurrent patellar dislocations.

IV.

Purpose The Covid-19 pandemic has disrupted health care systems all over the world. Elective surgical procedures have been postponed and/or cancelled. Consensus is, therefore, required related to the factors that need to be in place before elective surgery, including hip and knee replacement surgery, which is restarted. Entirely new pathways and protocols need to be worked out. Methods A panel of experts from the European Hip Society and European Knee Association have agreed to a consensus statement on how to reintroduce elective arthroplasty surgery safely. The recommendations are based on the best available evidence and have been validated in a separate survey. Results The guidelines are based on five themes: modification and/or reorganisation of hospital wards. Restrictions on orthopaedic wards and in operation suite(s). Additional disinfection of the environment. The role of ultra-clean operation theatres. Personal protective equipment enhancement. Conclusion Apart from the following national and local guidance, protocols need to be put in place in the patient pathway for primary arthroplasty to allow for a safe return.

Purpose The COVID-19 pandemic has disrupted the health care system around the entire globe. A consensus is needed about resuming total hip and knee procedures. The European Hip Society (EHS) and the European Knee Association (EKA) formed a panel of experts that have produced a consensus statement on how the safe re-introduction of elective hip and knee arthroplasty should be undertaken. Methods A prospective online survey was done among members of EHS and EKA. The survey consisted of 27 questions. It includes basic information on demographics and details the participant's agreement with each recommendation. The participant could choose among three options (agree, disagree, abstain). Recommendations focussed on pre-operative, perioperative, and post-operative handling of patients and precautions. Results A total of 681 arthroplasty surgeons participated in the survey, with 479 fully completing the survey. The participants were from 44 countries and 6 continents. Apart from adhering to National and Local Guidelines, the recommendations concerned how to make elective arthroplasty safe for patients and staff. Conclusion The survey has shown good-to-excellent agreement of the participants with regards to the statements made in the recommendations for the safe return to elective arthroplasty following the first wave of the COVID-19 pandemic.

V.