Dual-Mobility Constructs in Primary and Revision Total Hip Arthroplasty: A Systematic Review of Comparative Studies

Background

Utilization of dual-mobility constructs in total hip arthroplasties (THA) has increased in the recent years. Benefits and risks of these implants in terms of reducing dislocations, long-term survivorship, and associated complications are uncertain when compared to non-dual-mobility articulations.

Revision of Failed Metal-on-Metal Total Hip Arthroplasty: Midterm Outcomes of 203 Consecutive Cases

BackgroundMetal-on-metal (MoM) revisions have shown high rates of complications from aseptic loosening, deep infection, and dislocation. The purpose of this study is to report on outcomes and complications of a large consecutive series of patients who were revised for failed MoM total hip arthroplasty (THA).MethodsWe evaluated 188 patients (203 hips) who underwent revisions of failed MoM THA. Mean age at the revision was 60 years old. Gender was female in 112 hips (55%) and male in 91 hips (45%). Mean interval to failure after primary THA was 4.9 years (range, 0-18 years). The acetabular component was revised in 183 cases (92%). Clinical outcomes assessed included pain score and Harris hip score.ResultsMean follow-up from revision was 4.2 years. Harris hip score improved from 53.6 pre-revision to 73.5 at most recent follow-up (P < .001). Pain level significantly improved from 17.2 pre-revision to 32.8 post-revision (P < .001). Reoperations occurred in 28 (14%) hips. Re-revision was required in 16 hips (7.9%). The most common reasons for re-revision were aseptic loosening (5), dislocation (3), infection (2), and iliopsoas tendonitis (2). Re-revision was significantly higher in cases of pseudotumor. There was no difference in survival with ultraporous cups. Three hips required re-revision to custom triflange components. All-cause survival was 90.5% at 4.2 years. Metal ion levels significantly declined after revision.ConclusionRevisions of failed MoM THA showed improvements in clinical outcomes, but present significant surgical challenges and complications especially in cases with soft tissue damage and pseudotumor.     

Declining Revision Burden of Metal-on-Metal Hip Arthroplasties

BackgroundAdverse reactions to metal debris (ARMD) have been a problem with metal-on-metal (MoM) hip systems for a decade. Unacceptably high revision rates have been described for both stemmed MoM total hip arthroplasties (THAs) and hip resurfacings. The aim of this study was to report survivorship and temporal trends of hip revisions in patients with MoM hips.MethodsWe identified 2520 patients with 3013 MoM hip arthroplasties performed at our institution. These included 1532 primary stemmed MoM THAs, 1262 MoM hip resurfacings, and 219 stemmed MoM THAs implanted in revision surgery.ResultsRevision surgery was performed on 551 (36%) primary stemmed MoM THAs and on 179 (14%) resurfacings. The most common reason for revision was ARMD both among primary MoM THAs (83%) and hip resurfacings (70%). The 15-year implant survivorship was 69% (95% confidence interval [CI] 67-71%) for the whole study group, 56% (CI 53-60%) for stemmed primary MoM THAs, and 84% (CI 82-87%) for hip resurfacings. Clear temporal peak in the number of revisions for ARMD was seen in 2011-2013, and the trend has been decreasing since.ConclusionAfter a decade since outburst of the ARMD problematics with MoM hips, a large proportion of them have gone through revision surgery at our single high-volume center. The peak years were 2011-2013, and thereafter, the number of ARMD revisions has decreased every year. With the threshold for revision remaining constant at our institution, it is not likely that large amount of new cases of ARMD will be seen. As these results are derived from a single center's data, similar studies from other institutions are needed to see whether our results represent a global trend.     

Revision Total Hip Arthroplasty in Patients With Ankylosing Spondylitis: Long-Term Results

BackgroundAnkylosing spondylitis (AS) is a common inflammatory spondyloarthropathy with hip involvement in 40% of patients. With the recent interest in the hip-spine interplay, the purpose of this study was to define the long-term outcomes of revision total hip arthroplasty (THA) in the setting of AS.Methods174 hips in patients with AS treated with revision THA from 1969 to 2016 were identified. Mean age at revision THA was 53 years and 76% were male. Cumulative incidences of any re-revision, reoperation, and dislocation were calculated using a competing risk analysis. Mean follow-up was 13 years.ResultsThe cumulative incidence of any re-revision after index revision THA was 7% at 5 years and 36% at 20 years. Cumulative incidence of any reoperation was 9% at 5 years and 38% at 20 years. Cumulative incidence of dislocation was 6% at 5 years and 8% at 20 years. Revision THAs performed with contemporary implants (2000-2016) had a lower but statistically nonsignificant cumulative incidence of any re-revision when compared with historical implants (before 2000) at 5 years (5% vs 8%), 10 years (11% vs 18%), and 15 years (11% vs 38%) (hazard ratio, 0.47; 95% confidence interval, 0.17-1.33; P = .016).ConclusionIn this large series of 174 revision THAs in patients with AS, the cumulative incidence of dislocation was 8% at 20 years. The 20-year cumulative incidence of any re-revision was 36%, which is similar to reported rates in patients with comparable demographic features without AS.Level of EvidenceLevel IV.     

Dual-mobility cups for revision due to instability are associated with a low rate of re-revisions due to dislocation: 228 patients from the Swedish Hip Arthroplasty Register

Background and purpose

Revision total hip arthroplasty (THA) due to recurrent dislocations is associated with a high risk of persistent instability. We hypothesized that the use of dual-mobility cups would reduce the risk of re-revision due to dislocation after revision THA.

Patients and methods

228 THA cup revisions (in 228 patients) performed due to recurrent dislocations and employing a specific dual-mobility cup (Avantage) were identified in the Swedish Hip Arthroplasty Register. Kaplan-Meier survival analysis was performed with re-revision due to dislocation as the primary endpoint and re-revision for any reason as the secondary endpoint. Cox regression models were fitted in order to calculate the influence of various covariates on the risk of re-revision.

Results

58 patients (25%) had been revised at least once prior to the index cup revision. The surgical approach at the index cup revision was lateral in 99 cases (44%) and posterior in 124 cases (56%). Median follow-up was 2 (0–6) years after the index cup revision, and by then 18 patients (8%) had been re-revised for any reason. Of these, 4 patients (2%) had been re-revised due to dislocation. Survival after 2 years with the endpoint revision of any component due to dislocation was 99% (95% CI: 97–100), and it was 93% (CI: 90–97) with the endpoint revision of any component for any reason. Risk factors for subsequent re-revision for any reason were age between 50–59 years at the time of the index cup revision (risk ratio (RR) = 5 when compared with age > 75, CI: 1–23) and previous revision surgery to the relevant joint (RR = 1.7 per previous revision, CI: 1–3).

Interpretation

The risk of re-revision due to dislocation after insertion of dual-mobility cups during revision THA performed for recurrent dislocations appears to be low in the short term. Since most dislocations occur early after revision THA, we believe that this device adequately addresses the problem of recurrent instability. Younger age and prior hip revision surgery are risk factors for further revision surgery. However, problems such as potentially increased liner wear and subsequent aseptic loosening may be associated with the use of such devices in the long term.Treatment of repeated dislocations after total hip arthroplasty (THA) is challenging, and often has poor outcome (Alberton et al. 2002, Gioe 2002, Patel et al. 2007). This is especially true of dislocations that occur in elderly patients, after THA resulting from femoral neck fractures (Iorio et al. 2001) and following THA revision surgery (Khatod et al. 2006). The use of augments or constrained acetabular liners has been advocated in order to treat persistent THA instability. Constrained liners minimize the risk of dislocation but the rate of aseptic loosening of such devices is high in the long term (Yun et al. 2005, Williams et al. 2007)A different concept in the treatment of recurrent THA instability has been available since the introduction of dual-mobility or tripolar cups (Farizon et al. 1998). The principle of such constructs is the encasement of a regular-size femoral head component inside a larger-size polyethylene liner that in turn articulates with and moves within a metal shell fixed to acetabular bone. The use of such implants has been described in both primary and revision THA (Langlais et al. 2008, Philippot et al. 2009a, Bouchet et al. 2011, Boyer et al. 2012).We investigated re-revision rates of dual-mobility cups after revision THA that was performed due to recurrent dislocations and recorded in the Swedish Hip Arthroplasty Register. We hypothesized that the use of dual-mobility cups would result in a low risk of re-revision due to dislocation after revision THA in the short term. As a secondary endpoint, we analyzed the risk of re-revision for any reason and identified risk factors for re-revision.     

What Is the Dislocation and Revision Rate of Dual-mobility Cups Used in Complex Revision THAs?

BackgroundDual-mobility cups have been shown to reduce the dislocation risk after THA. Although dual-mobility cups can be a useful strategy to mitigate against recurrent dislocation after revision surgery, few clinical studies have focused on the results of complex revision THAs with extensive bone and soft-tissue loss or in patients who have undergone more than one previous surgical procedure.Questions/purposes(1) What is the survival free from revision for dislocation of dual-mobility cups used in complex revision THAs? (2) What is the survival free from any dislocation?MethodsBetween January 1, 2009 and December 31, 2013, 327 patients underwent a complex revision THA that included an acetabular revision, defined as preexisting massive bone loss in the acetabulum (at least Paprosky Type 2B) and/or proximal femur (at least Paprosky Type 3), substantial gluteal soft-tissue involvement, at least two previous surgical procedures or a one-stage septic revision, or history of dislocation. All 327 complex revision patients received a dual-mobility cup. Of those, 34% (111) were lost to follow-up before 5 years and were not known to have reached a study endpoint (revision for dislocation, and any dislocation) before then, leaving 216 patients for analysis. For patients with bilateral hip surgeries only the first operated hip was included for analysis. The median (range) follow-up duration was 69 months (60 to 110). The primary endpoint was dislocation or re-revision for dislocation. Fifty-six percent (120 of 216) of the patients were women and 44% (96 of 216) were men. The mean age of the patients was 69 ± 9 years. The patients underwent a median of four surgical procedures (1 to 4) before the index procedure (the revision evaluated in this study). A survival analysis was performed using the Kaplan-Meier method; any dislocation or revision for dislocation was determined as the endpoint.ResultsThe dislocation-free survival rates were 96% (95% confidence interval 92 to 98) at 5 years and 82% (95% CI 72 to 89) at 9 years. The overall dislocation rate was 11% (24 of 216 patients) at the final follow-up interval. Survival free of revision for dislocation was 99% (95% CI 96 to 100) at 5 years and 85% (95% CI 75 to 92) at 9 years.ConclusionsDual-mobility cups used in complex revision THA in this series had a higher rate of dislocation and revision than expected, based on earlier studies of dislocations of these components. Although we believe dual-mobility cups are still the first choice of implant if the patient has instability, these cups should be used cautiously if severe bone loss or soft-tissue involvement is present.Level of EvidenceLevel III, therapeutic study.     

Dual-Mobility Constructs in Revision Total Hip Arthroplasties

Dislocation after revision total hip arthroplasty (THA) continues to be one of the most common and concerning complications after the procedure. As with every hip arthroplasty, it is essential to optimize component positioning, minimize impingement, and maintain the integrity of the abductor complex during the revision THAs. However, in several revision circumstances, additional strategies are required to mitigate the risk of dislocation, particularly those being revised for instability or those with cognitive or neuromuscular disorders. In such revision THAs, dual-mobility constructs offer lower rates of dislocations and re-revisions for dislocations in the midterm. However, it is important to note that dual-mobility constructs should not be considered as compensation for poor surgical technique or technical errors such as poor cup orientation or inappropriate restoration of soft-tissue tension. While intraprosthetic dislocations are a unique complication to dual-mobility constructs, they are exceedingly rare. Furthermore, additional follow-up is required with modular dual-mobility constructs utilized with increasing frequency during revision THAs in North America.     

Clinical Outcomes and Midterm Survivorship of an Uncemented Primary Total Hip Arthroplasty System

BackgroundThe rise in total hip arthroplasty (THA) has led to a concomitant increase in revision THAs. Tracking implant performance therefore remains a significant element of scientific inquiry to garner and maintain public trust in this procedure. There are few available reports of outcomes of a single manufacturer’s total hip system outside registry data.MethodsWe performed a retrospective review of a prospectively generated database to evaluate outcomes of a single manufacturer’s femoral stem and acetabular shell for THA. We report the functional outcomes, revision data, and survivorship for this total hip system.ResultsA total of 1942 primary THAs were implanted into 1672 patients. There were of 57 revisions. There were no cases of acetabular failure at 10-year follow-up. All functional outcome scores demonstrated significant improvements following THA. Kaplan-Meier survival analysis for all-cause revisions demonstrated 2-year implant survival of 97.6% (95% confidence interval [CI], 96.9-98.3), 5-year implant survival of 97.3% (95% CI, 96.5-98.1), and 10-year implant survival of 97.0% (95% CI, 96.0-98.0). When infection was excluded, implant survivorship improved to 99.2% (95% CI, 98.8-99.6) at 2 years, 98.9% (95% CI, 98.5-99.4) at 5 years, and 98.7% (95% CI, 98.1-99.4) at 10 years.ConclusionThis THA implant system comprising an uncemented press-fit acetabulum used alongside a triple-tapered femoral stem is an excellent option for THA. Implant survivorship at 2, 5, and 10 years is among the best reported for any total hip system in the world.     

Fate of the Retained Acetabular Component During Revision Total Hip Arthroplasty: A Meta-Analysis and Systematic Review

BackgroundThe aim of this meta-analysis and systematic review is to estimate re-revision rates due to aseptic loosening of retained acetabular components after revision total hip arthroplasty.MethodsPubMed, EMBASE, Cochrane Library, and Web of Science were searched until June 11, 2018. Data were extracted by 2 independent investigators and consensus was reached with the involvement of a third investigator. Rates of re-revision due to aseptic loosening from 6 studies were aggregated using random effects model after a logit transformation and were grouped by study and population level characteristics.ResultsAn assessment of the re-revision rates of retained acetabular components due to aseptic loosening in revision total hip arthroplasty was reported in 6 studies involving 669 cases. The pooled re-revision rate was 12.6% (95% confidence interval 8.4-18.4) with a mean study follow-up of 8.6 years. The rate of re-revision due to aseptic loosening of retained acetabular components was 6.8% (95% confidence interval 3.4-13.3). In the univariate meta-regression analysis, mean age at index revision surgery was significantly associated with the rate of re-revision due to aseptic loosening (R² = 99.98%, P < .0001).ConclusionBased on this exploratory analysis, revision hip procedures with retentions of well-fixed acetabular components generally have a low risk of failure during mid-term to long-term follow-ups.     

Femoral Head Length Impact on Outcomes Following Total Hip Arthroplasty in 36 Millimeter Cobalt Chrome-on-Highly Crosslinked Polyethylene Articulations

BackgroundDespite concerns for corrosion, dislocation, and periprosthetic femur fractures, minimal literature has investigated the effect of adjusting femoral head length on outcomes after primary total hip arthroplasty (THA). Therefore, we aimed to investigate the effect of femoral head length on the risk of any revision and reoperation following cobalt chromium (CoCr)-on-highly crosslinked polyethylene (HXLPE) THAs.MethodsBetween 2004 and 2018, we identified 1,187 primary THAs with CoCr-on-HXLPE articulations using our institutional total joint registry. The mean age at THA was 71 years (range, 19-97), 40% were women, and mean body mass index was 30 (range, 10-68). All THAs using 36 mm diameter femoral heads were included. Neutral (0 mm), positive, or negative femoral head lengths were used in 42, 31, and 27% of the THAs, respectively. Kaplan-Meier survivorship was assessed. The mean follow-up was 7 years (range, 2-16).ResultsThe 10-year survivorships free of any revision or reoperation were 94 and 92%, respectively. A total of 47 revisions were performed, including periprosthetic femur fracture (17), periprosthetic joint infection (8), dislocation (7), aseptic loosening of either component (6), corrosion (4), and other (5). Nonrevision reoperations included wound revision (11), open reduction and internal fixation of periprosthetic femur fracture (4), and abductor repair (2). Multivariable analyses found no significant associations between femoral head length and revision or reoperation.ConclusionAltering femoral head lengths in 36 mm CoCr-on-HXLPE THAs did not affect outcomes. Surgeons should select femoral head lengths that optimize hip stability and center of rotation.Level of EvidenceIII.     

Cost-Effectiveness of Preoperative Spinal Imaging Before Total Hip Arthroplasty

BackgroundThe risk of instability, dislocation, and revision following total hip arthroplasty (THA) is increased in patients with abnormal spinopelvic mobility. Seated and standing lateral lumbar spine imaging can identify patients with stiff/hypermobile spine (SHS) to guide interventions such as changes in acetabular cup placement or use of a dual-mobility hip construct aimed at reducing dislocation risk.MethodsA Markov decision model was created to compare routine preoperative spinal imaging (PSI) to no screening in patients with and without SHS. Screened patients with SHS were assumed to receive dual-mobility hardware while those without SHS and nonscreened patients were assumed to receive conventional THA. Cost-effectiveness was determined by estimating the incremental cost-effectiveness ratio. Effectiveness measured as quality-adjusted life years (QALYs), with $100,000 per additional QALY as the threshold for cost-effectiveness. Sensitivity analyses were performed to determine the robustness of the base-case result.ResultsThe screening strategy with PSI had a lifetime cost of $12,515 and QALY gains of 16.91 compared with no-screening ($13,331 and 16.77). The PSI strategy reached cost-effectiveness at 5 years and was dominant (ie, less costly and more effective) at 11 years following THA. In sensitivity analyses, PSI remained the dominant strategy if prevalence of SHS was >1.9%, the cost of PSI was <$925, and the cost of dual-mobility hardware exceeded the cost of conventional hardware by <$2850.ConclusionScreening patients for SHS prior to THA with PSI is both less costly and more effective and should be considered as part of standard presurgical workup.     

Dual-mobility cups for revision due to instability are associated with a low rate of re-revisions due to dislocation

Background and purpose Revision total hip arthroplasty (THA) due to recurrent dislocations is associated with a high risk of persistent instability. We hypothesized that the use of dual-mobility cups would reduce the risk of re-revision due to dislocation after revision THA.

Patients and methods 228 THA cup revisions (in 228 patients) performed due to recurrent dislocations and employing a specific dual-mobility cup (Avantage) were identified in the Swedish Hip Arthroplasty Register. Kaplan-Meier survival analysis was performed with re-revision due to dislocation as the primary endpoint and re-revision for any reason as the secondary endpoint. Cox regression models were fitted in order to calculate the influence of various covariates on the risk of re-revision.

Results 58 patients (25%) had been revised at least once prior to the index cup revision. The surgical approach at the index cup revision was lateral in 99 cases (44%) and posterior in 124 cases (56%). Median follow-up was 2 (0–6) years after the index cup revision, and by then 18 patients (8%) had been re-revised for any reason. Of these, 4 patients (2%) had been re-revised due to dislocation. Survival after 2 years with the endpoint revision of any component due to dislocation was 99% (95% CI: 97–100), and it was 93% (CI: 90–97) with the endpoint revision of any component for any reason. Risk factors for subsequent re-revision for any reason were age between 50–59 years at the time of the index cup revision (risk ratio (RR) = 5 when compared with age > 75, CI: 1–23) and previous revision surgery to the relevant joint (RR = 1.7 per previous revision, CI: 1–3).

Interpretation The risk of re-revision due to dislocation after insertion of dual-mobility cups during revision THA performed for recurrent dislocations appears to be low in the short term. Since most dislocations occur early after revision THA, we believe that this device adequately addresses the problem of recurrent instability. Younger age and prior hip revision surgery are risk factors for further revision surgery. However, problems such as potentially increased liner wear and subsequent aseptic loosening may be associated with the use of such devices in the long term.     

Utilizing Dual Mobility Components for First-Time Revision Total Hip Arthroplasty for Instability

Background

Dislocation following total hip arthroplasty (THA) remains a significant clinical problem. Few studies have focused on the use of dual mobility (DM) components in the setting of first-time revision for instability following THA. Here, we investigate patient outcomes following first-time revision THA with DM components for a diagnosis of instability.

Dual Mobility for Monoblock Metal-on-Metal Revision—Is It Safe?

BackgroundRevision of monoblock metal-on-metal (MoM) total hip arthroplasty (THA) is associated with high complication rates. Limited revision by conversion to a dual mobility (DM) without acetabular component extraction may mitigate these complications. However, the concern for polyethylene wear and osteolysis remains unsettled. This study investigates the results of DM conversion of monoblock MoM THA compared to formal acetabular revision.MethodsOne hundred forty-three revisions of monoblock MoM THA were reviewed. Twenty-nine were revisions to a DM construct, and 114 were complete revisions of the acetabular component. Mean patient age was 61, 54% were women. Components used, acetabular cup position, radiographic outcomes, serum metal ion levels, and HOOS Jr clinical outcome scores were investigated.ResultsAt 3.9 years of follow-up (range 2-5), there were 2 revisions (6.9%) in the DM cohort, 1 for instability and another for periprosthetic fracture. Among the formal acetabular revision group there was a 20% major complication rate (23/114) and 16% underwent revision surgery (18/114) for aseptic loosening of the acetabular component (6%), deep infection (6%), dislocation (4%), acetabular fracture (3%), or delayed wound healing (6%). In the DM cohort, there were no radiographic signs of aseptic loosening, component migration, or polyethylene wear. One DM patient had a small posterior metadiaphyseal femur lesion that will require close monitoring. There were no other radiographic signs of osteolysis. There were no clinically significant elevations of serum metal ion levels. HOOS Jr scores were favorable.ConclusionLimited revision with conversion to DM is a viable treatment option for failed monoblock MoM THA with lower complication rates than formal revision. Limited revision to DM appears to be a safe option for revision of monoblock MoM THA with a cup in good position and an internal geometry free of sharp edges or articular surface damage. Longer follow-up is needed to demonstrate any potential wear implications of these articulations.     

Acetabular Component Position and the Risk of Dislocation Following Primary and Revision Total Hip Arthroplasty: A Matched Cohort Analysis

Background

Recently, the importance of acetabular component positioning in the Lewinnek “safe zone” in preventing prosthetic dislocation following total hip arthroplasty (THA) has been questioned. The purpose of this study was to determine the proportion of acetabular components within the Lewinnek safe zone between primary and revision THAs that have sustained a dislocation vs matched controls without a dislocation event.

Poor Short Term Outcome with a Metal-On-Metal Total Hip Arthroplasty

Metal-on-metal (MoM) bearings for total hip arthroplasty (THA) have come under scrutiny with reports of high failure rates. Clinical outcome studies with several commercially available MoM THA bearings remain unreported. We evaluated 78 consecutive MoM THAs from a single manufacturer in 68 patients. Sixty-six received cobalt–chrome (CoCr) monoblock and 12 received modular titanium acetabular cups with internal CoCr liners. Femoral components were titanium with modular necks. At average 2.1 years postoperatively, 12 THAs (15.4%) demonstrated aseptic failure (10 revisions, 2 revision recommended). All revised hips demonstrated capsular necrosis with positive histology reaction for aseptic lymphocytic vasculitis-associated lesions/adverse local tissue reactions. Prosthetic instability following revision surgery was relatively common. Female gender was a strong risk factor for failure, though smaller cups were not. Both monoblock and modular components fared poorly. Corrosion was frequently observed around the proximal and distal end of the modular femoral necks.     

A Minimum of 15-Year Results of Cementless Total Hip Arthroplasty Using a 28-mm Metal-On-Metal Articulation

BackgroundWe previously reported unexpected early failures of total hip arthroplasty (THA) utilizing a 28-mm Ultima metal-on-metal (MoM) articulation. However, long-term results of small-diameter MoM THAs still remain unclear. The purpose of this study was to evaluate the clinical and radiographic outcomes of the previously reported cohort at a minimum follow-up of 15 years.MethodsThe original cohort consisted of 171 primary THAs (167 patients) using a 28-mm MoM articulation performed between April 2000 and March 2002. Of these, 130 hips (126 patients) were reviewed at an average follow-up of 17.1 (range, 15-18) years. Clinical score, complications, presence of osteolytic lesion, serum metal ion concentrations, and implant survivorships were evaluated.ResultsThe mean Harris Hip Score improved from 44.9 points preoperatively to 90.5 points at the latest follow-up. During the entire period since the original surgery, a total of 5 revisions (3.8%) were associated with adverse reaction to metal debris (ARMD). The last revision surgery for symptomatic ARMD was performed at 6 years postoperatively. The implant survivorships with an end point of revision for aseptic failure and for any reason were 95.4% and 93.8%, respectively. Radiographic osteolytic lesions were detected in 27 hips (20.8%). The average serum metal concentration was 2.50 (range, 0.12-9.86) μg/L for cobalt and 2.81 (range, 0.82-12.3) μg/L for chromium.ConclusionsTHA using a 28-mm MoM articulation showed favorable long-term outcomes with a relatively high revision-free survival rate. There was no significant symptomatic ARMD after the last acetabular revision performed at 6 years postoperatively.     

Implant Survival of Constrained Acetabular Device in Primary Total Hip Arthroplasty Based on Data From the Finnish Arthroplasty Register

BackgroundConstrained acetabular devices were developed to prevent dislocations after total hip arthroplasty (THA). However, the data on their success have been contradictory. In this study, we aimed to assess implant survival of the constrained acetabular device in primary THA based on the Finnish Arthroplasty Register data.MethodsA total of 373 primary THAs with constrained acetabular devices inserted from 2006 to 2017 were included. A reference group was formed on a 1:3 basis and matched for age, sex, and diagnosis, consisting of 1118 conventional THAs. Implant survival estimates using death as a competing risk were assessed with revision for any reason and for any aseptic reason as the endpoints. The Cox multiple regression models were adjusted for age, sex, and diagnosis. The mean follow-up time was 3.3 (0-12.4) years for the constrained device group and 3.8 (0-12.0) years for the reference group.ResultsOverall, there were 21 revisions in the constrained device group and 49 in the reference group. The 8-year survivorship for any reason was 94% (confidence interval [CI]: 91-96) for the constrained device group and 93% (CI: 89-97) for the reference group. With revision for any aseptic reason as the endpoint, the 8-year survivorships were 97% (CI: 95-99) and 94% (CI: 90-98), respectively. During the first 1.5 years, the constrained acetabular device group had a similar revision risk (hazard ratio: 1.09 [CI: 0.57-2.07], P = .8) to that of the reference group.ConclusionThe constrained acetabular device had good survival in primary THA, and our results support its continued use even in high-risk patients.     

Monobloc Dual Mobility With a Minimum 5-Year Follow-Up: A Safe and Effective Solution in Primary Total Hip Arthroplasty

BackgroundInstability constitutes over 20% of revisions after total hip arthroplasty (THA). Dual mobility (DM) designs were introduced as a solution to this problem. However, the few publications that have reported promising results for monobloc DM constructs have been limited by sample size or length of follow-up. The purpose of this study is to evaluate mid-term outcomes (minimum 5-year follow-up) of a single-surgeon series utilizing a monobloc DM acetabular component in patients with high risk for dislocation.MethodsThis is a single-surgeon consecutive series of 207 primary THAs implanted with a monobloc DM component in patients who were considered at high risk for dislocation. Patient demographics and case-specific data were collected retrospectively. All patients had a minimum of 5-year follow-up. The Mann-Whitney U test was used to assess continuous variables, whereas categorical variables were analyzed using the chi-square test. Survival probability was calculated using the Kaplan-Meier method.ResultsRadiographic analysis did not reveal acetabular radiolucency in any patients, and there were no revisions for aseptic loosening. In addition, there were no dislocations. Seven of 205 patients (3.4%) were revised, 5 on the femoral side due to periprosthetic fracture and the remaining two for infection. Survivorship of the acetabular component from revision was 99%. The mean Veteran RAND (VR-12) physical score improved from 7 (standard deviation [SD]: 13.7) preoperatively to 9.5 (SD: 17.6) at the final follow-up. Similarly, the hip disability osteoarthritis score improved from 8 (SD: 17.9) preoperatively to 21.2 (SD: 37).ConclusionMonobloc DM components reliably prevent dislocation after primary THA in high-risk patients. At mid-term follow-up, this DM monobloc component demonstrates excellent implant survivorship, radiographic fixation, and improved functional outcomes.     

Dislocation After Debridement,Antibiotics, and Implant Retention for Periprosthetic Joint Infections of the Hip

BackgroundDebridement, antibiotics, and implant retention (DAIR) is a common treatment option for hip periprosthetic joint infection (PJI). However, noninfectious outcomes of DAIR such as instability are not well reported. The purpose of this study was to evaluate risk factors for hip dislocation post-DAIR for PJI of both primary and revision total hip arthroplasty (THA).MethodsA retrospective chart review identified all patients who underwent DAIR of a primary or revision THA over a 20-year period with a minimum 1-year follow-up. A total of 151 patients met inclusion criteria, 19.9% of whom had a post-DAIR dislocation. Demographic and intraoperative variables were obtained. Patients who had modular components exchanged during DAIR to those with increased offset, increased “jump distance”, or a more stable acetabular liner were defined as patients who had “components exchanged to increase stability.” Predictors of hip dislocation post-DAIR were inserted into a multivariate linear regression.ResultsPost-DAIR dislocation rates were 16.3% in primary THAs and 25.4% in revision THAs. In patients who had “components exchanged to increase stability” during hip DAIR, there was at least an 11-fold reduction (1/odds ratio (OR), 0.09) in dislocation risk compared to patients who had no components altered during modular component exchange during hip DAIR (OR, 0.09; 95% confidence interval, 0.02-0.44; P < .001), while a 13-fold increased dislocation risk was seen in patients with a history of neuromuscular disease (OR, 13.45; 95% confidence interval, 1.73-104.09; P = .01).ConclusionsDuring DAIR of hip PJI, surgeons should consider prophylactically exchanging components to increase stability even if components appear stable intraoperatively.