• Acetabular retroversion (AR) consists of a malorientation of the acetabulum in the sagittal plane. AR is associated with changes in load transmission across the hip, being a risk factor for early osteoarthrosis. The pathophysiological basis of AR is an anterior acetabular hyper-coverage and an overall pelvic rotation.

• The delay or the non-diagnosis of AR could have an impact in the overall management of femoroacetabular impingement (FAI). AR is a subtype of (focal) pincer deformity.

• The objective of this review was to clarify the pathophysiological, diagnosis and treatment fundaments inherent to AR, using a current literature review.

• Radiographic evaluation is paramount in AR: the cross-over, the posterior wall and ischial spine signs are classic radiographic signs of AR. However, computed tomography (CT) evaluation permits a three-dimensional characterization of the deformity, being more reliable in its recognition.

• Acetabular rim trimming (ART) and periacetabular osteotomy (PAO) are the best described surgical options for the treatment of AR.

• The clinical outcomes of both techniques are dependent on the correct characterization of existing lesions and adequate selection of patients.

Cite this article: EFORT Open Rev 2018;3:595-603. DOI: 10.1302/2058-5241.3.180015

• Total hip arthroplasty through an anterior approach has been increasing in popularity amongst surgeons and patients.

• Anterior approach hip arthroplasty seems to offer improved early outcomes in terms of pain, rehabilitation and length of stay.

• No difference in long-term outcomes has been shown between anterior and posterior or lateral approaches.

• Proper formal training, utilization of fluoroscopy and adequate experience can mitigate risks of complications and improve early and medium-term outcomes.

Cite this article: EFORT Open Rev 2018;3:574-583. DOI: 10.1302/2058-5241.3.180023.

• The increasing prevalence of obesity has resulted in a marked increase in the number of total hip arthroplasties (THAs) carried out in patients with a high body mass index (BMI).

• THA in morbidly obese patients is often technically challenging owing to the associated co-morbidities and anatomical factors. Furthermore, the long-term clinical and functional outcomes of the procedure in these patients are not clear.

• The aim of this systematic review was to compare the long-term failure rate and functional outcomes of THA in morbidly obese versus non-obese patients.

• A literature search of PubMed, EMBASE and PubMed Central was conducted to identify studies that compared the outcomes of THA in patients defined as morbidly obese (BMI ≥ 35) to a control group (BMI < 30). The primary and secondary outcome measures were rate of revision and functional outcome, respectively, in the long term.

• Eight studies were included in this review. There were 66,238 THAs in morbidly obese patients and 705,619 THAs in patients with a BMI < 30. The overall revision rate was 7.99% in the morbidly obese patients versus 2.75% in the non-obese controls. The functional outcome was at least comparable to non-obese patients.

• This review suggests that morbidly obese patients have a slightly increased revision rate following THA. Importantly, these patients have a functional recovery at least comparable to those with a BMI < 30. Morbidly obese patients should be fully informed of these issues prior to undergoing surgery.

Cite this article: EFORT Open Rev 2018;3:507-512. DOI: 10.1302/2058-5241.3.180011

• Atypical femoral fractures (AFF) are stress or ‘insufficiency’ fractures, often complicated by the use of bisphosphonates or other bone turnover inhibitors. While these drugs are beneficial for the intact osteoporotic bone, they probably prevent a stress fracture from healing which thus progresses to a complete fracture.

• Key features of atypical femoral fractures, essential for the diagnosis, are: location in the subtrochanteric region and diaphysis; lack of trauma history and comminution; and a transverse or short oblique configuration.

• The relative risk of patients developing an atypical femoral fracture when taking bisphosphonates is high; however, the absolute risk of these fractures in patients on bisphosphonates is low, ranging from 3.2 to 50 cases per 100,000 person-years.

• Treatment strategy in patients with AFF involves: radiograph of the contralateral side (computed tomography and magnetic resonance imaging should also be considered); dietary calcium and vitamin D supplementation should be prescribed following assessment; bisphosphonates or other potent antiresorptive agents should be discontinued; prophylactic surgical treatment of incomplete AFF with cephalomedullary nail, unless pain free; cephalomedullary nailing for surgical fixation of complete fractures; avoidance of gaps in the lateral and anterior cortex; avoidance of varus malreduction.

Cite this article: EFORT Open Rev 2018;3:494-500. DOI: 10.1302/2058-5241.3.170070.

• Acute peri-prosthetic joint infection (PJI) following total hip arthroplasty (THA) is a potentially devastating and undesired complication, with a prevalence of 0.3% to 2.9%. Its suspicion begins with a meticulous physical examination and anamnesis. Diagnosis should be made on the basis of the Musculoskeletal Infection Society criteria. Serum and synovial biomarkers are very useful tools when major criteria are absent.

• Although sometimes not possible due to medical conditions, surgery is usually the first line of treatment. Although its outcome is highly correlated with the isolated microorganism, irrigation and debridement with implant retention (DAIR) is the gold standard for treatment. Ideally, the prior approach should be proximally and distally extended to augment the field of view and remove all of the prosthetic modular components, that is, femoral head and acetabular insert.

• Given DAIR’s unclear control of infection, with successful outcomes in the range of 30% to 95%, one- or two-stage revision protocols may play a role in certain cases of acute infections; nonetheless, further prospective, randomized studies are necessary to compare long-term outcomes between DAIR and revision surgeries.

• Following surgical treatment, length of antibiotherapy is in the range of six weeks to six months, without any difference in outcomes between short and long protocols. Treatment should be adjusted to the isolated bacteria and controlled further with post-operative serum biomarker levels.

Cite this article: EFORT Open Rev 2018;3:434-441. DOI: 10.1302/2058-5241.3.170032

• Hip pain is highly prevalent in both the younger and the elderly population. In older patients, pain arising from osteoarthritis (OA) is most frequent, whereas in younger patients, non-degenerative diseases are more often the cause of pain. The pain may be caused by hip dysplasia and femoroacetabular impingement (FAI).

• Abnormal mechanics of the hip are hypothesized by some authors to cause up to 80% of OA in the hip. Therefore, correction of these abnormalities is of obvious importance when treating young patients with hip pain.

• Hip dysplasia can be diagnosed by measuring a CE angle < 25° on a plain standing radiograph of the pelvis.

• Dysplastic or retroverted acetabulum with significant symptoms should receive a periacetabular osteotomy (PAO).

• FAI with significant symptoms should be treated by adequate resection and, if necessary, labrum surgery.

• If risk factors for poor outcome of joint-preserving surgery are present (age > 45 to 50 years, presence of OA, joint space < 3 mm or reduced range of motion), the patient should be offered a total hip arthroplasty (THA) instead of PAO.

• THA can be performed following PAO with outcomes similar to a primary THA.

• Hip arthroscopy is indicated in FAI (cam and pincer) and/or for labral tears.

Cite this article: EFORT Open Rev 2018;3:408-417. DOI: 10.1302/2058-5241.3.170042

• Total hip arthroplasty (THA) is widely considered one of the most successful surgical procedures in orthopaedics. It is associated with high satisfaction rates and significant improvements in quality of life following surgery. On the other hand, the main cause of late revision is osteolysis and wear, often a result of failure of bearing surfaces.

• Currently, several options are available to the surgeon when choosing the bearing surface in THA (ceramic-on-ceramic (CoC), ceramic-on-polyethylene (CoPE), metal-on-polyethylene (MoPE)), each with advantages and drawbacks.

• Very few studies have directly compared the various combinations of bearings at long-term follow-up. Randomized controlled trials show similar short- to mid-term survivorship among the best performing bearing surfaces (CoC, CoXLPE and MoXLPE). Selection of the bearing surface is often ‘experience-based’ rather than ‘evidence-based’.

• The aim of this paper is therefore to evaluate the main advantages and drawbacks of various types of tribology in THA, while providing practical suggestions for the surgeon on the most suitable bearing surface option for each patient.

Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.180300.

• The use of larger femoral head size in total hip arthroplasty (THA) has increased during the past decade; 32 mm and 36 mm are the most commonly used femoral head sizes, as reported by several arthroplasty registries.

• The use of large femoral heads seems to be a trade-off between increased stability and decreased THA survivorship.

• We reviewed the literature, mainly focussing on the past 5 years, identifying benefits and complications associated with the trend of using larger femoral heads in THA.

• We found that there is no benefit in hip range of movement or hip function when head sizes > 36 mm are used.

• The risk of revision due to dislocation is lower for 36 mm or larger bearings compared with 28 mm or smaller and probably even with 32 mm.

• Volumetric wear and frictional torque are increased in bearings bigger than 32 mm compared with 32 mm or smaller in metal-on-cross-linked polyethylene (MoXLPE) THA, but not in ceramic-on-XLPE (CoXLPE).

• Long-term THA survivorship is improved for 32 mm MoXLPE bearings compared with both larger and smaller ones.

• We recommend a 32 mm femoral head if MoXLPE bearings are used. In hips operated on with larger bearings the use of ceramic heads on XLPE appears to be safer.

Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170061.

• Total hip arthroplasty (THA) is a very satisfactory surgical procedure for end-stage hip disorders.

• Implant modifications, such as large femoral heads to improve stability, porous metals to enhance fixation and alternative bearings to improve wear, have been introduced over the last decade in order to decrease the rate of early and late failures.

• There is a changing pattern of THA failure modes.

• The relationship between failure modes and patient-related factors, and the time and type of revision are important for understanding and preventing short and late failure of implants.

• The early adoption of innovations in either technique or implant design may lead to an increased risk of early failure.

Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170068

• Over the last two decades, several conservative femoral prostheses have been designed. The goals of conservative stems include: the spearing of the trochanteric bone stock; a more physiological loading in the proximal femur reducing the risk of stress shielding; and to avoid a long stem into the diaphysis preventing impingement with the femoral cortex and thigh pain.

• All stems designed to be less invasive than conventional uncemented stems are commonly named ‘short stems’. However, this term is misleading because it refers to a heterogeneous group of stems deeply different in terms of design, biomechanics and bearing. In the short-term follow-up, all conservative stems provided excellent survivorship. However, variable rates of complications were reported, including stem malalignment, incorrect stem sizing and intra-operative fracture.

• Radiostereometric analysis (RSA) studies demonstrated that some conservative stems were affected by an early slight migration and rotation within the first months after surgery, followed by a secondary stable fixation. Dual-energy x-ray absorptiometry (DEXA) studies demonstrated an implant-specific pattern of bone remodelling.

• Although the vast majority of stems demonstrated a good osseointegration, some prostheses transferred loads particularly to the lateral and distal-medial regions, favouring proximal stress shielding and bone atrophy in the great trochanter and calcar regions.

Cite this article: EFORT Open Rev 2018;3:149-159. DOI: 10.1302/2058-5241.3.170052