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• Prosthetic loosening has been debated for decades, both in terms of the timing and nature of the triggering events. Multiple radiostereometric studies of hip prostheses have now shown that early migration poses a risk of future clinical failure, but is this enough to explain late clinical loosening?

• To answer this question, the progression of loosening from initiation to radiographic detection is described; and the need for explanations other than early prosthetic loosening is analysed, such as stress-shielding, particle disease, and metal sensitivity.

• Much evidence indicates that prosthetic loosening has already been initiated during or shortly after the surgery, and that the subsequent progression of loosening is affected by biomechanical factors, fluid pressure fluctuations and inflammatory responses to necrotic cells and cell fragments, i.e. the concept of late loosening appears to be a misinterpretation of late-detected loosening.

• Clinical implications: atraumatic surgery and initial prosthetic stability are crucial in ensuring low risk of prosthetic loosening.

Cite this article: EFORT Open Rev 2020;5:113-117. DOI: 10.1302/2058-5241.5.190014

• Hip fractures are severe conditions with a high morbidity and mortality, especially when the diagnosis is delayed, and if formulated over 30 days after the injury, is termed a ‘neglected femoral neck fracture’ (NFNF).

• Cerebral palsy (CP) is probably one of the major risk factors for NFNF in Western countries, mainly because of both cognitive and motor impairments. However, considering the high prevalence of fractures in these patients, the incidence of NFNF in this population is probably underestimated, and this condition might result in persistent hip or abdominal pain.

• Several techniques are available for the treatment of NFNF (i.e. muscle pedicle bone graft, fixation with fibular graft, valgisation osteotomy), but most of them could affect motor function.

• Motor function must be preserved for as long as possible, in order to enhance the quality of life of CP patients.

• After discussing published NFNF cases in CP patients and available treatment options, a practical approach is proposed to facilitate the orthopaedic surgeon to both early identify and appropriately manage these challenging fractures.

Cite this article: EFORT Open Rev 2020;5:58-64. DOI: 10.1302/2058-5241.5.190019

• Excessive anterior pelvic tilt is suspected of causing femoroacetabular impingement, low back pain, and sacroiliac joint pain. Non-surgical treatment may decrease symptoms and is seen as an alternative to invasive and complicated surgery. However, the effect of non-surgical modalities in adults is unclear. The aim of this review was to investigate patient- and observer-reported outcomes of non-surgical intervention in reducing clinical symptoms and/or potential anterior pelvic tilt in symptomatic and non-symptomatic adults with excessive anterior pelvic tilt, and to evaluate the certainty of evidence.

• MEDLINE, EMBASE, Web of Science and Cochrane (CENTRAL) databases were searched up to March 2019 for eligible studies. Two reviewers assessed risk of bias independently, using the Cochrane Risk of Bias tool for randomized trials and the ROBINS-I tool for non-randomized studies. Data were synthesized qualitatively. The GRADE approach was used to assess the overall certainty of evidence.

• Of 2013 citations, two randomized controlled trials (RCTs) (n = 72) and two non-RCTs (n = 23) were included. One RCT reported a small reduction (< 2°) in anterior pelvic tilt in non-symptomatic men. The two non-RCTs reported a statistically significant reduction in anterior pelvic tilt, pain, and disability in symptomatic populations. The present review was based on heterogeneous study populations, interventions, and very low quality of evidence.

• No overall evidence for the effect of non-surgical treatment in reducing excessive anterior pelvic tilt and potentially related symptoms was found. High-quality studies targeting non-surgical treatment as an evidence-based alternative to surgical interventions for conditions related to excessive anterior pelvic tilt are warranted.

Cite this article: EFORT Open Rev 2020;5:37-45. DOI: 10.1302/2058-5241.5.190017

• Osteonecrosis of the femoral head is a poorly understood condition that may lead to progressive destruction of the hip joint. Its incidence is common between the third and fifth decades of life and it is the diagnosis behind 5–18% of annually performed total hip arthroplasties (THAs) in the USA.

• Regarding the high rate of complications of THA in that age group, authors have agreed on the importance of joint-preservation techniques for this disease but techniques vary to establish a generally accepted algorithmic approach.

• Surgical head-preserving procedures, core decompression with or without graft, stem cell augmentation, or biologic adjuncts, vascularized bone grafting, and proximal femoral osteotomies have all been published on with heterogeneous results and with limited evidence to date.

• Consensus states that the prognosis of patients with osteonecrosis of the femoral head can be significantly improved with early diagnosis and timely intervention.

Cite this article: EFORT Open Rev 2019;4:647-658. DOI: 10.1302/2058-5241.4.180073

• Total hip arthroplasty (THA) is one of the most successful surgical procedures – reducing pain and providing functional improvement. However, THA instability is a disabling condition and remains the most common indication for revision THA. To combat the risk of instability, the concept of dual mobility (DM) was developed. This article provides a comprehensive review of DM in the literature.

• Widespread use of first-generation DM was limited due to concern regarding wear of the polyethylene head and the unique complication of intraprosthetic dislocation (IPD). Implant modifications using highly cross-linked, durable polyethylene and a smooth, cylindrical femoral neck have all but eliminated IPD in contemporary DM.

• In multiple studies, DM demonstrates statistically significant reductions in dislocation rates comparative to standard bearing primary THA. These results have been particular promising in high-risk patient populations and femoral neck fractures – where low dislocation rates and improved functional outcomes are a recurrent theme. From an economic perspective, DM is equally exciting – with lower accrued costs and higher accrued utility comparative to standard bearing THA.

• Longer-term clinical evidence and higher-quality prospective comparative studies are required to strengthen current research. Dual mobility may well represent the future gold standard for THA in high-risk patient populations and femoral neck fractures, but due diligence of long-term performance is needed before recommendations for widespread use can be justified.

Cite this article: EFORT Open Rev 2019;4:640-646. DOI: 10.1302/2058-5241.4.180089

• Prosthetic joint infection (PJI) is associated with poor clinical outcomes and is expensive to treat.

• Although uncommon overall (affecting between 0.5% and 2.2% of cases), PJI is one of the most commonly encountered complications of joint replacement and its incidence is increasing, putting a significant burden on healthcare systems.

• Once established, PJI is extremely difficult to eradicate as bacteria exist in biofilms which protect them from antibiotics and the host immune response.

• Improved understanding of the microbial pathology in PJI has generated potential new treatment strategies for prevention and eradication of biofilm associated infection including modification of implant surfaces to prevent adhesion of bacteria.

• Much research is currently ongoing looking at different implant surface coatings and modifications, and although most of this work has not translated into clinical medicine there has been some early clinical success.

Cite this article: EFORT Open Rev 2019;4:633-639. DOI: 10.1302/2058-5241.4.180095

• Robotic total hip arthroplasty (THA) improves accuracy in achieving the planned acetabular cup positioning compared to conventional manual THA.

• Robotic THA improves precision and reduces outliers in restoring the planned centre of hip rotation compared to conventional manual THA.

• Improved accuracy in restoring hip biomechanics and acetabular cup positioning in robotic THA have not translated to any differences in early functional outcomes, correction of leg-length discrepancy, or postoperative complications compared to conventional manual THA.

• Limitations of robotic THA include substantive installation costs, additional radiation exposure, steep learning curves for gaining surgical proficiency, and compatibility of the robotic technology with a limited number of implant designs.

• Further higher quality studies are required to compare differences in conventional versus robotic THA in relation to long-term functional outcomes, implant survivorship, time to revision surgery, and cost-effectiveness.

Cite this article: EFORT Open Rev 2019;4:618-625. DOI: 10.1302/2058-5241.4.180088

• Preoperative planning is mandatory to achieve the restoration of a correct and personalized biomechanics of the hip.

• The radiographic review is the first and fundamental step in the planning. Limb or pelvis malpositioning during the review results in mislead planning.

• Correct templating is possible using three different methods: acetate templating on digital X-ray, digital 2D templating on digital X-ray and 3D digital templating on CT scan.

• Time efficiency, costs, reproducibility and accuracy must be considered when comparing different templating methods. Based on these parameters, acetate templating should not be abandoned; digital templating allows a permanent record of planning and can be electronically viewed by different members of surgical team; 3D templating is intrinsically more accurate. There is no evidence in the few recently published studies that 3D templating impacts positively on clinical outcomes except in difficult cases.

• The transverse acetabular ligament (TAL) is a reliable intraoperative soft tissue reference to set cup position.

• Spine–hip relations in osteoarthritic patients undergoing hip joint replacement must be considered.

Cite this article: EFORT Open Rev 2019;4:626-632. DOI: 10.1302/2058-5241.4.180075

• Many studies in the literature have been carried out to evaluate the various cellular and molecular processes involved in osteogenesis.

• Angiogenesis and bone formation work closely together in this group of disorders. Hypoxia-inducible factor (HIF) which is stimulated in tissue hypoxia triggers a cascade of molecular processes that helps manage this physiological deficiency.

• However, there still remains a paucity of knowledge with regard to how sickle cell bone pathology, in particular avascular necrosis, could be altered when it comes to osseointegration at the molecular level.

• Hypoxia-inducible factor has been identified as key in mediating how cells adapt to molecular oxygen levels.

• The aim of this review is to further elucidate the physiology of hypoxia-inducible factor with its various pathways and to establish what role this factor could play in altering the disease pathophysiology of avascular necrosis caused by sickle cell disease and in improving osseointegration.

• This review article also seeks to propose certain research methodology frameworks in exploring how osseointegration could be improved in sickle cell disease patients with total hip replacements and how it could eventually reduce their already increased risk of undergoing revision surgery.

Cite this article: EFORT Open Rev 2019;4:567-575. DOI: 10.1302/2058-5241.4.180030

• Hip instability following total hip arthroplasty (THA) remains a major challenge and is one of the main causes of revision surgery.

• Dual mobility (DM) implants have been introduced to try to overcome this problem. The DM design consists of a small femoral head captive and mobile within a polyethylene liner.

• Numerous studies have shown that DM implants reduce the rate of dislocation compared to fixed-bearing inserts.

• Early designs for DM implants had problems with wear and intra-prosthetic dislocations, so their use was restricted to limited indications.

• The results of the latest generation of DM prostheses demonstrate that these problems have been overcome. Given the results of these studies presented in this review, surgeons may now consider DM THA for a wider patient selection.

Cite this article: EFORT Open Rev 2019;4:541-547. DOI: 10.1302/2058-5241.4.180045