• 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

• Ankylosing Spondylitis (AS) can commonly involve the hip joint and cause significant mobility problems. Total hip arthroplasty (THA) on a single side alone will not restore mobility in patients with bilateral disease.

• We performed a systematic review of the available literature to determine the changes in objective outcome measures and complications of bilateral THA in patients with advanced AS. Four studies, a total of 114 THAs, were included in the study. The average patient age was 32.9 years and the average follow-up time was 59.5 months.

• All studies reported a significant improvement in hip function, patient satisfaction and patient mobility following bilateral THA. Harris Hip Score (HHS) improved by a mean of 60.6 points post-operatively.

• Complications included five intra-operative fractures (4.4%) and three transient nerve palsies (2.6%). There were two dislocations (1.8%) that were successfully managed with closed reduction. Seven hips required revision, with the most common cause being aseptic loosening. Twelve hips (10.5%) developed heterotopic ossification consistent with Brooker Class 1 or 2 with no reports of re-ankylosis.

• This review suggests that bilateral THA is a safe and effective treatment of advanced hip disease in AS. Attention must be paid to the highly demanding technical aspects of this procedure to reduce the risk of significant complications.

• Debate still exists on the ideal prosthesis, fixation method and approach to use but this review presents data from several series of uncemented prostheses that have good post-operative results.

Cite this article: EFORT Open Rev 2019;4:476-481. DOI: 10.1302/2058-5241.4.180047

• Traumatic neurological lesions may lead to development of heterotopic ossification. These cases are classified as ‘neurogenic heterotopic ossifications’ (NHOs). The associated neurological lesions can be caused by cranial trauma or spinal cord injury and may sometimes include a local trauma.

• NHOs that form around the hip joints are of particular interest because they often cause the patient to avoid the sitting position or the resumption of walking.

• Whilst NHO can involve the knee, shoulder and elbow joints, hip-involving NHOs are more numerous, and sometimes develop in close contact with vascular or neurological structures.

• Multi-disciplinary clinical examination is fundamental to evaluate patients for surgical intervention and to define the objectives of the surgery. The best investigation to define an NHO mass is a computerized tomography (CT) scan.

• Resection is performed to liberate a fused joint to provide functionality, and this need not be exhaustive if it is not necessary to increase the range of motion.

• While recurrence does occur post-surgery, a partial resection does not pose a greater risk of recurrence and there are no adjuvant treatments available to reduce this risk.

• The greatest risks associated with NHO surgical resection are infection and haematoma; these risks are very high and must be considered when evaluating patients for surgery.

Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180098

• Osteonecrosis of the femoral head is a disabling pathology affecting a young population (average age at treatment, 33 to 38 years) and is the most important cause of total hip arthroplasty in this population. It reflects the endpoint of various disease processes that result in a decrease of the femoral head blood flow.

• The physiopathology reflects an alteration of the vascularization of the fine blood vessels irrigating the anterior and superior part of the femoral head. This zone of necrosis is the source of the loss of joint congruence that leads to premature wear of the hip.

• Several different types of medication have been developed to reverse the process of ischemia and/or restore the vascularization of the femoral head. There is no consensus yet on a particular treatment.

• The surgical treatments aim to preserve the joint as far as the diagnosis could be made before the appearance of a zone of necrosis and the loss of joint congruence. They consist of bone marrow decompressions, osteotomies around the hip, vascular or non-vascular grafts.

• Future therapies include the use of biologically active molecules as well as implants impregnated with biologically active tissue.

Cite this article: EFORT Open Rev 2019;4:85-97. DOI: 10.1302/2058-5241.4.180036

• Total hip arthroplasty (THA) is one of the most commonly performed orthopaedic procedures. Some concern exists that trainee-performed THA may adversely affect patient outcomes. The aim of this meta-analysis was to compare outcomes following THA performed by surgical trainees and consultant surgeons.

• A systematic search was performed to identify articles comparing outcomes following trainee- versus consultant-performed THA. Outcomes assessed included rate of revision surgery, dislocation, deep infection, mean operation time, length of hospital stay and Harris Hip Score (HHS) up to one year. A meta-analysis was conducted using odds ratios (ORs) and weighted mean differences (WMDs). A subgroup analysis for supervised trainees versus consultants was also performed.

• The final analysis included seven non-randomized studies of 40 810 THAs, of which 6393 (15.7%) were performed by trainees and 34 417 (84.3%) were performed by consultants. In total, 5651 (88.4%) THAs in the trainee group were performed under supervision. There was no significant difference in revision rate between the trainee and consultant groups (OR 1.09; p = 0.51). Trainees took significantly longer to perform THA compared with consultants (WMD 12.9; p < 0.01). The trainee group was associated with a lower HHS at one year compared with consultants (WMD -1.26; p < 0.01). There was no difference in rate of dislocation, deep infection or length of hospital stay between the two groups.

• The present study suggests that supervised trainees can achieve similar clinical outcomes to consultant surgeons, with a slightly longer operation time. In selected patients, trainee-performed THA is safe and effective.

Cite this article: EFORT Open Rev 2019;4:44-55. DOI: 10.1302/2058-5241.4.180034.

• 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