Causes for revision of dual-mobility and standard primary total hip arthroplasty A Dual-mobility Cup Reduces Risk of Dislocation in Isolated Acetabular Revisions Can Dual Mobility Cups prevent Dislocation in All Situations After Revision Total Hip Arthroplasty? Dislocation of Primary Total Hip Arthroplasty with 36 and 40-mm Femoral Heads Early experience with dual mobility acetabular systems featuring highly cross-linked polyethylene liners for primary hip arthroplasty in patients under fifty five years of age: an international multi-centre preliminary study Comparison of dual-mobility cup and unipolar cup for prevention of dislocation after revision total hip arthroplasty Cementless dual-mobility cup in total hip arthroplasty revision Influence of preoperative patient education on the risk of dislocation after primary total hip arthroplasty. Dual mobility cups hip arthroplasty as a treatment for displaced fracture of the femoral neck in the elderly. A prospective, systematic, multicenter study with specific focus on postoperative dislocation. Dual-Mobility Cup and Cemented Femoral Component: 6 Year Follow-Up Results Are Hip Precautions Necessary Post Total Hip Arthroplasty? A Systematic Review The dual-mobility POLARCUP: first results from a multicenter study. Relationship of Femoral Head and Acetabular Size to the Prevalence of Dislocation Large femoral heads decrease the incidence of dislocation after total hip arthroplasty: a randomized controlled trial. Surgical dislocation of the hip versus arthroscopic treatment of femoroacetabular impingement: a prospective matched-pair study with average 2-year follow-up. Dislocation after total hip arthroplasty using Hueter anterior approach. Total hip arthroplasty and hemiarthroplasty in mobile, independent patients with a displaced intracapsular fracture of the femoral neck. A randomized, controlled trial.
Introduction The causes for revision of primary total hip arthroplasty ( THA ) are various and quite well known . The developing use of dual-mobility THA ( DM-THA ) seems a relevant option to decrease the risk of instability . Due to lack of long-term follow-up , this innovative retentive concept is suspected to increase the risk of polyethylene ( PE ) wear . the aim of the study was to analyse the causes for  DM-THA revision and assess whether or not its occurrence is different from that of fixed-st and ard ( FS ) THA , particularly for aseptic loosening or wear and /or osteolysis . Material s and methods The SoFCOT group conducted an observational prospect i ve multicentre study from 1 January 2010 to 31 December 2011 . Inclusion criteria comprised an exhaustive collection of 2044 first-revision THAs with 251 DM-THAs and 1793 FS-THAs . After excluding complications linked to patient factors ( infection and periprosthetic fractures ) , we performed a matched case – control study ( matching ratio 1:1 ) comparing two groups of 133 THAs . Results Revisions for aseptic loosening or osteolysis/wear were as frequent in DM-THA ( 58.7 % ) as in FS-THA ( 57.1 % ) ( p 0.32 ) ; 7.5 % of DM-THA were revised for dislocation versus 19.5 % of FS-THA ( p 0.007 ) . Discussion Revision for osteolysis/wear and aseptic loosening were as frequent in DM-THA as in FS-THA ;  revision for dislocation was less frequent in DM-THA . This confirms the efficiency of the DM concept regarding the risk of dislocation . Causes for revision were different between groups , and revisions for dislocation were less frequent in DM-THA . Only prospect i ve comparative studies could provide reliable information that may support broader use of the DM concept Background Isolated acetabular revisions using st and ard cups are at risk of dislocation . The introduction of a nonconstrained dual-mobility cup was design ed to improve prosthetic stability without increasing loosening rates , but it is unclear whether the risk of dislocation is reduced . Questions / purpose sWe therefore determined : ( 1 ) if the rate of dislocation in isolated acetabular revisions is lower with a dual-mobility cup , ( 2 ) implant survival , ( 3 ) patient function , and ( 4 ) radiographic incidence of migration , loosening , and osteolysis . Methods We prospect ively followed 33 selected patients who underwent isolated acetabular revisions with a minimum of 2 years ’ followup ( mean , 3 years ; range , 2–5 years ) . In 24 patients a stainless steel dual-mobility cup was cemented into an antiprotrusio cage , whereas in nine we used a hyaluronan dual-mobility revision cup with a foramen hook and superior and posterior flanges screw fixations . We determined Harris hip ( HHS ) and WOMAC scores and examined radiographs for migration , loosening , and osteolysis . Results There were no dislocations . Survivorship rates of the femoral and acetabular components were 97 % at 5 years ; the rerevision rate for any reason was 3 % . At last followup , the mean HHS increased from 48 points preoperatively to 86 points . No patients had progressive osteolysis , component migration , or loosening on radiographs . Conclusion In this select group of isolated acetabular revisions , our data suggest the use of a dual-mobility cup reduced the risk of dislocation without increasing loosening from 2 to 5 years . Level of Evidence Level IV , therapeutic study . See the Guidelines for Authors for a complete description of levels of evidence UNLABELLED The outcome of a single design of dual mobility cup was prospect ively evaluated in a continuous series of 994 revision THAs with respect to dislocation and intra-prosthetic dislocation ( IPD ) . At a 7.3-year mean follow-up , the dislocation rate was 1.5 % and the IPD rate was 0.2 % . The 2 IPD occurred in acetabular-only revisions and were related to a poor head-to-neck ratio with early impingement and wear at the polyethylene mobile component chamfer . Dual mobility cups demonstrated a low dislocation rate in revision THA but did not compensate for potential perioperative technical errors . In addition , IPD did not appear to be a concern with respect to the benefit in term of instability prevention though caution is advised in acetabular-only revision associated with a poor head-to-neck ratio . LEVEL OF EVIDENCE Therapeutic study -Level IV Some authors suggest the use of larger ( 36 and 40 mm ) femoral heads against highly cross-linked polyethylene acetabular liners will reduce the prevalence of early dislocation after primary total hip arthroplasty ( THA ) . We prospect ively followed 61 consecutive patients at high risk for dislocation to determine the prevalence of early dislocation after primary THA with 36 and 40 mm femoral heads .  We established specific indications for the use of these larger heads in primary arthroplasty . There were 65 hips in 61 patients with a minimum followup of 1 year ( mean 2 years , range 1 - 4 years ) . There were 55 36 mm heads and 10 40 mm heads . All arthroplasties were performed by the posterior approach with capsular repair . The prevalence of early dislocation was 4.6 % ( 3 of 65 ) . There was one patient with an anterior dislocation and two with posterior dislocation . No patient underwent reoperation for dislocation . There was no dislocation in the 10 hips that had a 40 mm head . We identified no complications related to the larger femoral heads . The use of larger femoral heads did not notably reduce the prevalence of early dislocation after primary THA in high risk patients compared to historical controls . Therapeutic study : Level IV , case series . See Guidelines for Authors for a complete description of levels of evidence Purpose To evaluate early performance of contemporary dual mobility acetabular systems with second generation annealed highly cross-linked polyethylene for primary hip arthroplasty of patients under 55 years of age . Methods A prospect i ve observational five years study across five centers in Europe and the USA of 321 patients with a mean age of 48.1 years was performed . Patients were assessed for  causes of revision , hip instability , intra-prosthetic dissociation , Harris hip score and radiological signs of osteolysis .  Results There were no dislocations and no intra-prosthetic dissociations . Kaplan Meier analysis demonstrated 97.51 % survivorship for all cause revision and 99.68 % survivorship for acetabular component revision at five years . Mean Harris hip score was 93.6 . Two acetabular shells were revised for neck-rim implant impingement without dislocation and ten femoral stems were revised for causes unrelated to dual mobility implants . Conclusion Contemporary highly cross-linked polyethylene dual mobility systems demonstrate excellent early clinical , radiological , and survivorship results in a cohort of patients that dem and high performance from their implants . It is envisaged that DM and second generation annealed HXLPE may reduce THA instability and wear , the two most common causes of THA revision in hip arthroplasty Background and purpose — Revision total hip arthroplasty ( THA ) is associated with higher dislocation rates than primary THA . We compared the risk of dislocation within 6 months and all-cause re-revision during the whole study period using either the dual-mobility cup or the unipolar cup . Methods — We used a prospect i ve hospital registry-based cohort including all total and cup-only revision THAs performed between 2003 and 2013 . The cups used were either dual-mobility or unipolar ; the choice was made according to the preference of the surgeon . 316 revision THAs were included . The mean age of the cohort was 69 ( 25–98 ) years and 160 THAs ( 51 % ) were performed in women . The dual-mobility group ( group 1 ) included 150 THAs ( 48 % ) and the mean length of follow-up was 31 ( 0–128 ) months . The unipolar group ( group 2 ) included 166 THAs ( 53 % ) and the mean length of follow-up was 52 ( 0–136 ) months . Results — The incidence of dislocation within 6 months was significantly lower with the dual-mobility cup than with the unipolar cup ( 2.7 % vs. 7.8 % ) . The unadjusted risk ratio ( RR ) was 0.34 ( 95 % CI : 0.11–1.02 ) and the adjusted RR was 0.28 ( 95 % CI : 0.09–0.87 ) . The number of patients needed to treat with a  dual-mobility cup in order to prevent 1 case of dislocation was 19 . The unadjusted incidence rate ratio for all-cause re-revision in the dual-mobility group compared to the unipolar group was 0.6 ( 95 % CI : 0.3–1.4 ) . Interpretation — Use of a dual-mobility rather than a unipolar cup in revision THA reduced the risk of dislocation within 6 months Purpose Dislocation is a frequent complication in total hip arthroplasty ( THA ) revision . Cup fixation is the second concern . In order to know outcomes at two years , we prospect ively followed a continuous series of 78 patients to demonstrate that  cementless dual-mobility cup ( DMC ) used in revision THA  is safe as regards dislocation risk and bone fixation . Method We enrolled 78 consecutive patients ( 79 cases ) in a prospect i ve study . Mean interval between index surgery and revision was 12.9 years . Mean age at revision was 75.5 years . Two types of cementless DMC were used : a st and ard DMC in 68 cases with low- grade bone defect ( Paprosky grade 1 and 2 ) , and a specific design reconstruction DMC in 11 cases with severe bone loss ( Paprosky grade 3 ) . Results At two years of follow-up , 68 patients were review ed ; four were lost to follow-up . , and six patients were deceased . We identified three types of situations at risk : st and ard risk ( 33 cases ) , Paprosky grade 1 or 2 ; medium risk ( 37 cases ) , revision for recurrent instability ( 21 ) , periprosthetic fractures ( 14 ) or severe loosening Paprosky grade 3 without femorotomy ( 2 ) ; high risk ( nine cases ) , revision for severe loosening with a femorotomy . One ( 1.3 % ) patient dislocated her hip at one month without recurrence . Revision rate for dislocation was 0 % ; two ( 2.7 % ) early mechanical failures occurred . Conclusion Considering outcomes of this series , cementless DMC can be suggested in THA revision surgery OBJECTIVE Dislocation is a well-known complication after  total hip arthroplasty ( THA ) , and is the second-highest cause of revision surgery . Our objective was to assess the effect of preoperative patient education on the occurrence of  hip dislocation  within 6 months after primary THA . METHODS Between 1998 and 2007 , we conducted a prospect i ve cohort study at the Geneva University Hospital Department of Orthopaedic Surgery , including all primary THAs performed via an anterolateral transgluteal approach with the use of a 28-mm diameter head .  The preoperative education session was introduced in June 2002 and included advice on muscle strengthening exercises and postoperative restrictions of range of motion as a means of preventing dislocation . The main outcome was the incidence of dislocation within 6 months of surgery . RESULTS A total of 597 patients who underwent 656 THAs between June 2002 and June 2007 participated in the education session , whereas 1,641 patients who underwent 1,945 procedures did not . Forty-six dislocations occurred over the study period , 5 ( 0.8 % ) in participants and 41 ( 2.1 % ) in non participants ( absolute risk reduction 1.3 % ; 95 % confidence interval [ 95 % CI ] 0.4 , 2.3 ) , with the time interval between surgery and dislocation being significantly shorter among participants ( 0.2 versus 1.2 months ) . Non participants had a 2.8 times higher risk of dislocation than participants ( unadjusted odds ratio [ OR ] 2.80 ; 95 % CI 1.10 , 7.13 ) . Adjustment for age , sex , comorbidities , and prior surgery did not change the results ( adjusted OR 2.79 ; 95 % CI 1.09 , 7.15 ) . CONCLUSION Our findings suggest that participation in a preoperative patient education session may reduce the risk of dislocation within 6 months after THA INTRODUCTION Displaced fractures of the femoral neck in the elderly are best treated with arthroplasty . The type of arthroplasty to be used , either hemi- or total hip arthroplasty , remains controversial as total hip replacements potentially have a higher rate of dislocation . HYPOTHESIS Dual mobility cups have a low dislocation rate when used to manage acute fractures of the femoral neck . PATIENTS AND METHODS In a multicenter prospect i ve study conducted in France over an inclusion time of 3 months , all displaced fractures of the femoral neck treated with arthroplasty  were operated on with insertion of a dual mobility cup . Patients had clinical and radiological assessment at 3 , 6 , and 9 months postoperative . RESULTS Two hundred and fourteen hips in 214 patients with a mean age of 83 years ( range , 70 - 103 years ) were included . None of the patients was lost to follow-up . The mortality rate after 9 months was 19 % . Two patients ( 1 % ) had early postoperative infection successfully treated with lavage and antibiotics . Three patients ( 1.4 % ) , operated through a posterior approach , presented one postoperative dislocation , all of which were posterior . Reduction was performed through closed external manipulation under general anesthesia . There was no recurrence of dislocation . DISCUSSION This low rate of dislocation after acute total hip replacement using dual mobility design cups favorably compares with hemiarthroplasties . Dual mobility cups might therefore be considered a valuable option to prevent postoperative dislocation when treating displaced intracapsular fractures of the proximal femur in elderly patients if a total hip replacement is recommended . Further study is needed before extending the indications for total hip arthroplasty following a fracture of the femoral neck , to assess the potential cost and complications of a longer procedure with its potential acetabular complication , and weigh them against the potential benefits Use of a dual-mobility acetabular cup is associated with a lower risk of dislocation compared with conventional hip implants . The seleXys ® DS acetabular cup combines the advantages of Charnley low-friction arthroplasty with those of dual mobility . We performed a non-r and omised , prospect i ve study of patients receiving primary hip arthroplasty , including an uncemented seleXys ® DS dual-mobility acetabular cup with hydroxyapatite coating ( Mathys AG , Bettlach , Switzerl and ) and a cemented femoral component ( Stallion femoral stem Groupe Lepine , Lyon , France ) . The objective of the study was to evaluate longevity of the implant and the risk of dislocation . All operations were performed by a single surgeon using a posterior approach , with patients lying in the lateral decubitus position . The stem had a modular head diameter of 22.2 mm and was cemented in all patients . A total of 53 patients were studied , and the median duration of follow-up was 78.9 months . Implant survival 6 years after surgery was 98.4 % ( n=47 ; 95 % CI : 89.3–99.8 ) . There was one revision for sepsis 29 months after surgery , and one dislocation . The results of this study appear to demonstrate excellent implant survival and a low rate of dislocation using the chosen implants Purpose : Total hip arthroplasty ( THA ) is a common and effective treatment of hip osteoarthritis . Activity restrictions known as hip pre caution s are widely practice d in rehabilitation post THA , aim ing to foster healing and prevent hip dislocation . The focused clinical question was : Does the application of hip pre caution s in patients post THA versus unrestricted activities significantly decrease the risk of prosthetic dislocation ? Methods : A comprehensive literature search was conducted for r and omized controlled trials or cohort studies with a comparative group and minimum 6 months follow-up , with dislocation as an end point . Retrieved titles were assessed independently by 2 review ers for inclusion and underwent st and ardized data extraction . Results : Title search produced 80 potentially relevant articles . Five articles were retrieved for data extraction of which 2 met a prior eligibility criteria . No eligible studies were found that concerned posterior approaches to hip arthroplasty , so the results of this review concern only anterolateral approaches . Neither included study showed any benefit of hip pre caution s in preventing dislocation . Conclusion : The rate of dislocation after anterolateral THA is low and is not improved by hip pre caution s. Hip pre caution s are associated with a slower return to activities , significant expense , and decreased patient satisfaction . Existing studies risk being compromised by a type II error , but a definitive study may be prohibitively large and expensive Dislocation is a leading cause of revision after  total hip arthroplasty ( THA ) . To address this risk , dual-mobility technology was developed , which features a mobile polyethylene liner locked onto a femoral head and articulating in a metallic acetabular shell . This study reports clinical outcome data after implantation of the third-generation POLARCUP Dual-Mobility System ( Smith & Nephew Orthopaedics AG , Rotkreuz , Switzerl and ) .  Primary THA procedures were performed in 150 patients . At 7.1 years , cumulative cup survival according to Kaplan-Meier was 97.4 % . The mean Postel-Merle d'Aubigne score improved from 8.9 to 17.1 during the investigation . Two cups were revised at 5.4 and 6.4 years because of aseptic loosening . No dislocations were observed during follow-up . The current results confirm excellent early to midterm clinical outcomes for the POLARCUP Dual-Mobility System Two clinical studies , one prospect i ve r and omized and one retrospective , were performed to evaluate the relationship of femoral head size and acetabular component outer diameter to the prevalence of dislocation of the  modular total hip replacement . Between October 1995 and April 1996 , 31 primary total hip arthroplasties in 30 patients were r and omized to a femoral head diameter of 22 mm or 28 mm , for two groups of acetabular components of outer diameters of 56 mm or larger and 54 mm or smaller . Head size ( 22 mm ) and acetabular component outer diameter ( ≥ 56 mm ) were found to increase the risk of dislocation . From December 1984 to January 1994 , 308 primary total hip arthroplasties were performed through a posterior approach by one surgeon using a modular 28 mm femoral head and one type of uncemented acetabular component .  The rate of dislocation for acetabular components with an outer diameter of 62 mm or larger was increased significantly ( five of 36 hips , 14 % ) compared with those with an outer diameter of 60 mm or smaller ( 11 of 272 hips , 4 % ) BACKGROUND The use of larger femoral heads has been proposed to reduce the risk of dislocation after total hip arthroplasty , but there is a lack of evidence to support this proposal . The aim of this multicenter r and omized controlled trial was to determine whether the incidence of dislocation one year after total hip arthroplasty is significantly lower in association with the use of a 36-mm femoral head articulation as compared with a 28-mm articulation . METHODS Six hundred and forty-four middle-aged and elderly patients undergoing primary or revision arthroplasty were r and omized intraoperatively to receive either a 36 or 28-mm metal femoral head on highly cross-linked polyethylene .  Patients who were at high risk of dislocation ( including those with dementia and neuromuscular disease ) and those undergoing revision for the treatment of recurrent hip dislocation or infection were excluded . Patients were stratified according to other potential risk factors for dislocation , including diagnosis and age . Diagnosis of hip dislocation required confirmation by a physician and radiographic evidence of a dislocation . RESULTS Overall , at one year of follow-up , hips with a 36-mm femoral head articulation had a significantly lower incidence of dislocation than did those with a 28-mm articulation ( 1.3 % [ four of 299 ] compared with 5.4 % [ seventeen of 316 ] ; difference , 4.1 % [ 95 % confidence interval , 1.2 % to 7.2 % ] ) when controlling for the type of procedure ( primary or revision ) ( p = 0.012 ) . The incidence of dislocation following primary arthroplasty was also significantly lower for hips with a 36-mm femoral head articulation than for those with a 28-mm articulation ( 0.8 % [ two of 258 ] compared with 4.4 % [ twelve of 275 ] ; difference , 3.6 % [ 95 % confidence interval , 0.9 % to 6.8 % ] ) ( p = 0.024 ) . The incidence of dislocation following revision arthroplasty was 4.9 % ( two of forty-one ) for hips with a 36-mm articulation and 12.2 % ( five of forty-one ) for hips with a 28-mm articulation ; this difference was not significant with the relatively small sample size of the revision group ( difference , 7.3 % [ 95 % confidence interval , -5.9 % to 21.1 % ] ) ( p = 0.273 ) . CONCLUSIONS Compared with a 28-mm femoral head articulation , a larger 36-mm articulation result ed in a significantly decreased incidence of dislocation in the first year following primary total hip arthroplasty . However , before a 36-mm metal-on-highly cross-linked polyethylene articulation is widely recommended , the incidence of late dislocation , wear , periprosthetic osteolysis , and liner fracture should be established PURPOSE The purpose of this study was to prospect ively compare outcomes of patients receiving surgical hip dislocation and those undergoing arthroscopic treatment for femoroacetabular impingement ( FAI ) , using a matched-pair analysis . METHODS Between January 2008 and August 2011 , patients aged 30 years or younger with a diagnosis of FAI treated with surgical dislocation or arthroscopy were included . Patients were excluded with Tönnis grade 2 or greater , dysplasia , Legg-Calve-Perthes disease , and previous hip surgery . Patients treated with surgical dislocation  were pair-matched to patients treated arthroscopically in a 1:2 ratio . Patient-reported outcomes were prospect ively obtained in all patients preoperatively and postoperatively at 3 months , at 1 year , at 2 years , and at latest follow-up . Alpha angles were measured preoperatively and postoperatively for both groups . Revision surgery and complications were recorded for each group . RESULTS Ten patients were included in the surgical dislocation group , and 20 pair-matched patients were included in the arthroscopic group . We obtained 100 % follow-up at a mean of 24.8 months in the open group and 25.5 months in the arthroscopic group . Preoperative scores were similar between the 2 groups ; significant improvements were made postoperatively for both groups . When we compared the 2 groups , the change in Hip Outcome Score-Sport-Specific Subscale ( 42.8 v 23.5 , P = .047 ) and 2-year Non-Arthritic Hip Score ( 94.2 v 85.7 , P = .01 ) were significantly higher in the arthroscopic group . Both groups showed a significant decrease in the alpha angle postoperatively ( P = .775 ) . CONCLUSIONS Favorable results were shown with both approaches , with significant improvement in all patient-reported outcome measures and high patient satisfaction ratings . However , arthroscopic treatment of FAI showed greater improvement in the Hip Outcome Score-Sport-Specific Subscale and a higher absolute Non-Arthritic Hip Score at an average 2-year follow-up . LEVEL OF EVIDENCE Level II , prospect i ve matched-pair comparative study A prospect i ve study including 1764 hips has been carried out to evaluate the frequency of dislocation while using the Hueter anterior approach and the correlated factors . The dislocation group was compared with the patients without dislocation . We observed 27 dislocations ( 1.5 % ) . The dislocation rate when using 28 mm head diameter was 0.5 % . Two patients underwent a revision for recurrent dislocations . Correlated factors for dislocation were male sex , high body mass index , etiology of osteonecrosis , low head diameter , high bleeding , and low postoperative ROM . Dislocation risk while using Hueter approach is one of the lowest in the literature . The main disadvantages are the necessity for a specific orthopedic table and a more difficult exposure of the femur BACKGROUND Hemiarthroplasty and total hip arthroplasty are commonly used to treat displaced intracapsular fractures of the femoral neck , but each has disadvantages and the optimal treatment of these fractures remains controversial . METHODS In the present prospect ively r and omized study , eighty-one patients who had been mobile and lived independently before they had sustained a displaced fracture of the femoral neck were r and omized to receive either a total hip arthroplasty or a hemiarthroplasty .  The mean age of the patients was seventy-five years . Outcome was assessed with use of the Oxford hip score , and final radiographs were assessed . RESULTS After a mean duration of follow-up of three years , the mean walking distance was 1.17 mi ( 1.9 km ) for the hemiarthroplasty group and 2.23 mi ( 3.6 km ) for the total hip arthroplasty group , and the mean Oxford hip score was 22.3 for the hemiarthroplasty group and 18.8 for the total hip arthroplasty group . Patients in the total hip arthroplasty group walked farther ( p=0.039 ) and had a lower ( better ) Oxford hip score ( p=0.033 ) than those in the hemiarthroplasty group . Twenty of thirty-two living patients in the hemiarthroplasty group had radiographic evidence of acetabular erosion at the time of the final follow-up . None of the hips in the hemiarthroplasty group dislocated , whereas three hips in the total hip arthroplasty group dislocated . In the hemiarthroplasty group , two hips were revised to total hip arthroplasty and three additional hips had acetabular erosion severe enough to indicate revision . In the total hip arthroplasty group , one hip was revised because of subsidence of the femoral component . CONCLUSIONS Total hip arthroplasty conferred superior short-term clinical results and fewer complications when compared with hemiarthroplasty in this prospect ively r and omized study of mobile , independent patients who had sustained a displaced fracture of the femoral neck
Conclusion Based on the current data , the use of DM acetabular components are effective in minimising the risk of instability after both primary and revision THA .
This benefit must be balanced against continuing concerns about the additional modularity , and the new mode of failure of intraprosthetic dislocation .
Aims The aim of this systematic review was to report the rate of dislocation following the use of dual mobility ( DM ) acetabular components in primary and revision total hip arthroplasty ( THA ) .