Extension of the Direct Anterior Approach for the Treatment of Periprosthetic Femoral Fractures

BackgroundPeriprosthetic femoral fractures (PFFs) after total hip arthroplasty are devastating complications often resulting in functional limitations and increased mortality. The use of the direct anterior approach (DAA) is becoming more popular, and the number of revisions done through this interval is increasing. The DAA interval can be expanded to treat PFFs. This retrospective case series assessed outcomes of PFF patients treated with the extension of the DAA interval.MethodsThe study contained 40 patients (40 hips). Mean patient age was 74.3 years (range, 55.1-92.2 years). Mean follow-up time was 50.4 months (range, 20-98.2 months). Fractures were classified as Vancouver B2 (n = 36) and B3 (n = 4).ResultsMedian cut-to-close time was 152 minutes (interquartile range: 80-279). There were five complications (12.5%): 2 deaths, 1 transient femoral nerve palsy, 1 fissure distal to the stem, and 1 hematoma.ConclusionExpansion of the DAA interval to treat PFF showed similar results compared with other surgical approaches in terms of mortality, complications, fracture healing, and dislocation rate. These results indicate that femoral revision for PFF in the DAA interval is a safe and reliable procedure compared with other surgical approaches for the treatment of Vancouver B2 and B3 periprosthetic fractures.     

Excellent Long-Term Survival Rate of Polished,Tapered, Cemented Stems in Patients Aged 35 Years or Younger With Avascular Necrosis or Inflammatory Arthritis of the Hip

BackgroundTotal hip arthroplasty (THA) for avascular necrosis (AVN) or inflammatory arthritis (IA) comes with a relatively high risk of aseptic stem loosening, especially in young patients. There are limited long-term data on the survivorship of polished, tapered, cemented stems in this population. We therefore performed a single-center retrospective study investigating the survival of this particular stem type in young patients with AVN or IA.MethodsAll patients aged ≤35 years who had received a THA for AVN or IA operated on by the senior author between 1990 and 2010 at the University Hospitals Leuven were identified. In total, 85 THAs in 62 patients were included. Primary endpoint was revision of the femoral component for aseptic loosening. Secondary endpoints were revision of the acetabular component for aseptic loosening, revision for other reasons, and the presence of radiolucencies around the components.ResultsThe mean follow-up for the entire cohort was 18.0 ± 5.3 years (range 8.0-28.9). Taking revision for aseptic loosening as endpoint, the survival of cemented stems was 100% after 15 years and 95.1% after 20 years. Survival of uncemented cups (91.3%) was significantly better than survival of cemented cups (50.3%) after 20 years of follow-up for aseptic loosening. Taking revision for any reason as endpoint, the survival of THAs with uncemented and cemented cups was 90% and 43.1% at 20 years respectively. Radiolucencies developed in the cement mantles around 11 of the 81 nonrevised stems, mainly in zones 1 and 7.ConclusionIn this cohort of young patients with high-risk profiles for aseptic stem loosening, polished, tapered, cemented stems showed excellent long-term survival rates and they therefore remain a viable alternative to uncemented stem designs.     

Component Placement in Direct Lateral vs Minimally Invasive Anterior Approach in Total Hip Arthroplasty: Radiographic Outcomes From a Prospective Randomized Controlled Trial

BackgroundEnd-stage coxarthrosis is increasingly common; however, limited evidence exists on the effect of direct lateral approach (DLA) and minimally invasive direct anterior approach (MIDA) on component placement in total hip arthroplasty (THA). We therefore conducted a prospective, randomized controlled trial to determine the component placement in DLA vs MIDA in THA.MethodsBetween January 2012 and June 2013, 164 patients with clinically and radiologically confirmed coxarthrosis aged 20-80 years were randomized to either DLA or MIDA (active comparator). Excluded were patients with previous ipsilateral hip surgery, a body mass index >35 kg/m², and/or mental disability. Primary clinical outcomes have been published elsewhere. Secondary outcomes included radiographic assessment of the acetabular component (cement-mantle thickness, inclination, and anteversion), femoral stem position (varus/valgus and THA index), offset restoration, and leg length discrepancy.ResultsThe mean cement-mantle was significantly thicker in zone 1 in the MIDA group (mean difference = 0.51 mm, 95% confidence interval [CI] 0.09-0.93, P = .018), and the mean degrees of inclination and anteversion were higher in the MIDA group (mean difference = 2.5°, 95% CI 0.3-4.6, P = .023 and mean difference = 3.6°, 95% CI 2.2-5.0, P < .0001, respectively). According to the defined reference range, cup inclination was more often adequate in the DLA group (67.9% (53/78) in the DLA group vs 52.4% (43/82) in the MIDA group, P = .045). There were no differences in frontal or lateral femoral stem position, global offset restoration, or leg length discrepancy.ConclusionIn this population of Norwegian patients with coxarthrosis, radiographic assessment showed limited differences in component placement between MIDA and DLA. The findings suggest that component placement is similar in the 2 surgical approaches.     

Polished,Collarless, Tapered,Cemented Stems for Primary Hip Arthroplasty May Exhibit High Rate of Periprosthetic Fracture at Short-Term Follow-Up

Background

Cemented stems are designed to follow 1 of 2 principles of fixation: composite beams or slide taper. Stems in the latter category have a collarless, polished, tapered (CPT) design and subside into the cement mantle, creating hoop stresses. We compared the rate of periprosthetic fracture (PPF) of stem designed with these 2 principles of fixation. In addition, we examined radiographic factors that may predispose to the development of PPF.

Risk Factors for Periprosthetic Femur Fracture and Influence of Femoral Fixation Using the Mini-Anterolateral Approach in Primary Total Hip Arthroplasty

BackgroundThe mini-anterolateral (AL) approach for total hip arthroplasty (THA) has gained popularity. In contrast to other approaches, risk factors for periprosthetic femur fractures have not been well established for the AL approach.MethodsSix hundred eighty-four primary THAs performed using the AL approach were retrospectively reviewed for risk factors associated with perioperative periprosthetic femur fractures within 3 months of surgery. Risk factors evaluated were gender, age, body mass index, laterality, and Dorr ratio of the proximal femur. Cemented stems and collared uncemented stems were compared to uncemented tapered-wedge and meta-diaphyseal stems. A Student’s t-test was used for continuous variables, and a chi-squared test was used for categorical variables.ResultsOf 684 primary THAs performed, 57 (8.3%) resulted in fracture. Twenty-eight (4.1%) occurred intraoperatively and 29 (4.2%) occurred postoperatively within 90 days. All intraoperative fractures were fixed at the time of surgery and healed uneventfully. Of the postoperative fractures, 15 (2.2%) were amenable to nonoperative management and healed. Fourteen (2.0%) required revision arthroplasty. There was a significantly lower rate of fracture in patients receiving cemented or collared stems (0%, n = 101) than in those receiving tapered-wedge or meta-diaphyseal fitting stems (9.8%, n = 583; P = .0009). Odds of fracture increased with female gender (P = .0063) and increasing Dorr ratio (P = .0003). Analysis showed a trend toward increased risk with older age, but did not achieve statistical significance. Body mass index and laterality showed no statistically significant effect.ConclusionPerforming primary THA via the AL approach, 2.0% of patients had a postoperative fracture requiring revision within the first 3 months. With cemented and collared stems, the fracture rate was significantly lower. Surgeons should consider using cemented or collared stems in high-risk patients.     

Mid-term results of Exeter vs Endurance cemented stems

The mid-term results are reported of 2 uniquely different cemented stems implanted and followed prospectively by a single surgeon. The highly polished, collarless, tapered Exeter stem and the Endurance stem, a collared, roughened, satin finished stem, were inserted through a lateral approach using third-generation cement techniques. A total of 118 hips with the Exeter stem with an average follow-up of 7.25 years and 34 hips with the Endurance stem with an average follow-up of 4.57 years are included in the study. The Exeter patients had no revisions for aseptic loosening (0%) of the femoral stem. In contrast, the Endurance patients had 5 revisions and 2 impending revisions for aseptic loosening (20.5%) of the femoral stem with an average time to failure of 3.72 years. The excellent mid-term results of the Exeter stem support its ongoing use. By contrast, because of the poor early results of this modern cemented Endurance stem design, it is no longer used at our institution.     

Predictors of Perioperative Vancouver B Periprosthetic Femoral Fractures Associated With the Direct Anterior Approach to Total Hip Arthroplasty

BackgroundThere is an association between intraoperative and postoperative femoral fractures and the direct anterior approach (DAA) to total hip arthroplasty (THA). The purpose of our study is to identify risk factors for Vancouver B fractures and to establish a predictable timeline for when these occur.MethodsWe retrospectively identified patients with Vancouver B periprosthetic femoral fractures (n = 49) after 11,509 elective primary cementless THA procedures through the DAA between 2012 and 2018 at a single institution. Fracture patients were matched to nonfracture patients (n = 267) by date of surgery and surgeon. Clinical and radiographic factors were collected for multivariable analysis to identify predictors of fracture.ResultsPeriprosthetic Vancouver B femoral fracture incidence was 0.4%. 48 (98%) fractures were postoperative. Fractures occurred at an average of 44 days after surgery (range: 1 to 653 days) with >85% of fractures occurring in the first 6 weeks postoperatively. Significant variables predictive of fracture included >3 degrees valgus and >5 degrees varus coronal stem malalignment, Dorr B and C femoral geometry, lower canal flare index (2.75 vs 3.20), advanced age, increased comorbidities, greater stem canal fill, and right-sided procedures.ConclusionDespite an overall low rate of Vancouver B perioperative periprosthetic femoral fractures, it is a devastating complication that typically presents within the first 6 weeks after DAA THA surgery. The risk is increased in patients with unfavorable proximal femoral geometry, coronal stem malalignment, advanced age, increased comorbidities, and right-sided procedures.     

Polished Cemented Femoral Stems Have a Lower Rate of Revision Than Matt Finished Cemented Stems in Total Hip Arthroplasty: An Analysis of 96,315 Cemented Femoral Stems

Background

Matt and polished femoral stems have been historically grouped together in registry assessment of the outcome of cemented femoral stems in total hip arthroplasty. This is despite differences in the mode of fixation and biomechanics of loading. The aims of this study are to compare the survivorship of polished tapered stems with matt finished cemented stems.

Can Arthroplasty Stem Influence Outcome: A Randomized Controlled Trial of Stem Length in Cemented Total Hip Arthroplasty

BackgroundThe primary aim was to assess whether a short (125 millimeter (mm)) stem offered an equivalent hip-specific function compared to the standard (150 mm) stem when used for cemented total hip arthroplasty. Secondary aims were to evaluate health-related quality of life, patient satisfaction, stem height and alignment, as well as radiographic loosenings and complications between the two stems.MethodsA prospective twin-center double-blind randomized control trial was conducted. During a 15-month period, 220 patients undergoing total hip arthroplasty were randomized to either a standard (n = 110) or a short (n = 110) stem. There were no significant (P ≥ .065) differences in preoperative variables between the groups. Functional outcomes and radiographic assessment were undertaken at a mean of 1 and 2 years.ResultsThere were no differences (P = .428) in hip-specific function according to the mean Oxford hip scores at 1 year (primary endpoint) or at 2 years (P = .622) between the groups. The short stem group had greater varus angulation (0.9 degrees, P = .003) when compared to the standard group and were more likely (odds ratio 2.42, P = .002) to have varus stem alignment beyond one standard deviation from the mean. There were no significant (P ≥ .083) differences in the forgotten joint scores, EuroQol-5-Dimension, EuroQol-visual analogue scale, short form 12, patient satisfaction, complications, stem height, or radiolucent zones at 1 or 2 years between the groups.ConclusionThe cemented short stem used in this study had equivalent hip-specific function, health-related quality of life, and patient satisfaction when compared to the standard stem at mean 2 years post operation. However, the short stem was associated with a greater rate of varus malalignment, which may influence future implant survival.     

A Comparison of Risk of Dislocation and Cause-Specific Revision Between Direct Anterior and Posterior Approach Following Elective Cementless Total Hip Arthroplasty

BackgroundUse of the direct anterior approach (DAA) for total hip arthroplasty (THA) has increased over the last decade. We sought to investigate whether (1) a difference exists in dislocation risk for DAA compared with posterior THA, (2) a difference exists in risk for specific revision reasons, and (3) the likelihood of adverse 90-day postoperative events differs.MethodsWe conducted a cohort study using data from Kaiser Permanente’s Total Joint Replacement Registry. Patients aged ≥18 years who underwent primary cementless THA for osteoarthritis with a highly cross-linked polyethylene liner were included (2009-2017). Multivariable Cox proportional hazards regression was used to evaluate dislocation and cause-specific revision risks, and multivariable logistic regression was used to evaluate 90-day emergency department visits, 90-day unplanned readmissions, and 90-day complications (including deep infection, deep vein thrombosis, and pulmonary embolism).ResultsOf 38,399 primary THA, 6428 (16.7%) were DAA. All-cause revision at 2-years follow-up was 1.78% (95% confidence interval [CI] = 1.46-2.17) for DAA and 2.28% (95% CI = 2.11-2.45) for posterior. After adjusting for covariates, DAA had a lower risk of dislocation (hazard ratio [HR] = 0.39, 95% CI = 0.29-0.53), revision for instability (HR = 0.33, 95% CI = 0.18-0.58), revision for periprosthetic fracture (HR = 0.57, 95% CI = 0.34-0.96), and readmission (odds ratio = 0.82, 95% CI = 0.67-0.99) compared with posterior approach but a higher risk of revision for aseptic loosening (HR = 2.26, 95% CI = 1.35-3.79).ConclusionWhile the DAA associated with lower risks of dislocation and revision for instability and periprosthetic fracture, it is associated with a higher revision risk for aseptic loosening. Surgeons should discuss these risks with their patients.     

No Difference in the Rate of Periprosthetic Joint Infection in Patients Undergoing the Posterolateral Compared to the Direct Anterior Approach

BackgroundThere remains inconsistent data about the association of surgical approach and periprosthetic joint infection (PJI). We sought to evaluate the risk of reoperation for superficial infection and PJI after primary total hip arthroplasty (THA) in a multivariate model.MethodsWe reviewed 16,500 primary THAs, collecting data on surgical approach and all reoperations within 1 year for superficial infection (n = 36) or PJI (n = 70). Considering superficial infection and PJI separately, we used Kaplan–Meier survivorship to assess survival free from reoperation and a Cox Proportional Hazards multivariate models to assess risk factors for reoperation.ResultsBetween direct anterior approach (DAA) (N = 3,351) and PLA (N = 13,149) cohorts, rates of superficial infection (0.4 versus 0.2%) and PJI (0.3 versus 0.5%) were low and survivorship free from reoperation for superficial infection (99.6 versus 99.8%) and PJI (99.4 versus 99.7%) were excellent at both 1 and 2 years. The risk of developing superficial infection increased with high body mass index (BMI) (hazard ratio [HR] = 1.1 per unit increase, P = .003), DAA (HR = 2.7, P = .01), and smoking status (HR = 2.9, P = .03). The risk of developing PJI increased with the high BMI (HR = 1.04, P = .03), but not surgical approach (HR = 0.68, P = .3).ConclusionIn this study of 16,500 primary THAs, DAA was independently associated with an elevated risk of superficial infection reoperation compared to the PLA, but there was no association between surgical approach and PJI. An elevated patient BMI was the strongest risk factor for superficial infection and PJI in our cohort.Level of EvidenceIII, retrospective cohort study.     

In vitro cyclic testing of the Exeter stem after cement within cement revision

Cement-within-cement (C-C) revision arthroplasty minimizes the complications associated with removal of secure polymethylmethacrylate. Failure at the interfacial region between new and old cement mantles remains a theoretical concern. This article assesses the cyclic fatigue properties of bilaminar cement mantles after C-C revision in vitro with the Exeter stem. Seven Exeter stems were cemented into Sawbone femurs and removed, and new undersized stems were cemented into the preserved mantle. The new constructs were loaded for 1,000,000 cycles at body temperature. Cement mantles were inspected postcycling. In no case was there delamination or failure of the cement mantle. The findings support the hypothesis that use of a thin revision cement mantle in conjunction with a polished double-tapered stem is not detrimental to the overall success of the implant. In the presence of a secure cement-bone interface in suitable patients, we recommend C-C revision techniques using double-tapered polished femoral stems.     

Collarless polished tapered stem: clinical and radiological follow-up over 5 years

The clinical and radiologic outcome of a cemented, polished, tapered stem (CPT), implanted using contemporary cementing techniques in 108 consecutive operated hips in 100 patients (68 women and 32 men, aged 19 to 83 years at the time of surgery [mean, 65 years]) was assessed after >5 years. The Harris hip scores were good or excellent in 96% of the patients. Stem subsidence measured by the computer-assisted method described by Braud and Freeman was at a mean rate of 0.44 mm/y, 1.08 mm during the first year, and stabilizing to a mean total of 2.18 mm at >5 years. Subsidence was related inversely to the completeness of the cement mantle but did not correlate with the clinical or radiologic outcome. This study confirms that collarless, polished, tapered stems subside within the cement mantle but without loosening and that the CPT performs at least as well as the Exeter stem.     

Cemented Polished Tapered Stems Have Lower Revision Rates Than Commonly Used Cementless Implant up to 17 Years of Follow-Up: An Analysis of 201,889 Total Hip Replacements From the Australian Orthopedic Association National Joint Replacement Registry

BackgroundData assessing femoral stems may be influenced by grouping together matt and polished stems, despite their differing reported survivorship. The aim of this study is to assess the difference in revision rates between commonly used cemented and cementless stems when polished tapered stems are assessed independently of matt stems.MethodsAustralian Orthopaedic Association National Joint Replacement Registry data from 1999 to 2019 were used to assess difference in revision rates between the 5 most commonly implanted femoral cemented and cementless stems for osteoarthritis. Cemented matt femoral stems, stems using line-to-line cementing techniques and procedures using non-cross-linked polyethylene, large head (>32 mm) metal-on-metal bearing surfaces or exchangeable necks were excluded. Cumulative percent revision was used to help compare survivorship between stems.ResultsThere were 201,889 total hip replacements meeting the inclusion criteria, of which 50.0% were cemented and 50.0% cementless. Cemented stems had a lower rate of revision at all time points compared to cementless stems. This was most significant during the first 2 weeks (hazard ratio 0.48, 95% confidence interval 0.40-0.58, P < .001) compared to 2 weeks postoperatively and onwards (hazard ratio 0.85, 95% confidence interval 0.81-0.90, P < .001). A subanalysis of head size, bearing type, and surgeon volume further supported the use of a cemented stem.ConclusionCommonly used cemented polished tapered stems have a lower revision rate when compared to commonly used cementless prostheses, and are recommended in all age groups for both low-volume and high-volume surgeons especially when head size 32 mm or smaller is used.     

Femoral stem dislodgement during bipolar hemiarthroplasty dislocation

Bipolar hemiarthroplasty remains a treatment option for displaced femoral neck fractures in elderly patients without pre-existing hip disease. Implant-related complications associated with this procedure include acetabular erosion, dislocation, disassembly of the modular components, polyethylene debris-induced osteolysis, metallosis from outer cup impingement, and femoral component loosening. This article presents a case of a patient in whom the polished collarless tapered femoral stem dislodged out of the cement mantle during traumatic bipolar hemiarthroplasty dislocation, 28 days after the index procedure. This complication, associated with bipolar hemiarthroplasty dislocation, was adequately managed by driving the stem back to the original cement mantle, followed by reduction of bipolar component dislocation and placing bone cement over the shoulder of the femoral stem to prevent a new dislodgement episode. Although rare, dislodgement of cemented polished collarless tapered stems from the cement mantle has been recently reported either during dislocation or, more frequently, as a complication of reduction of a dislocated total hip arthroplasty. However, its occurrence in association with bipolar hemiarthroplasty dislocation was not found to have been reported in the literature. The occurrence of femoral stem dislodgement during bipolar hemiarthroplasty dislocation should be considered as a possible complication of such a procedure and may be prevented by routinely placing bone cement over the shoulder of the femoral implant.     

Cement-within-cement stem exchange using the collarless polished double-taper stem

The clinical and radiographic outcomes of the cement-within-cement femoral stem exchange technique at revision hip arthroplasty were determined. Twenty-three revisions with a collarless polished double-taper stem design were prospectively monitored at up to 12 years. The most common indications for revision were recurrent dislocation and acetabular revision. Radiographic stem subsidence was measured by the Ein Bild Röentgen Analyse method. There was no stem re-revision and no radiographic loosening. Stem within cement subsidence, an intentional design feature of this stem, averaged 0.8 mm (range, 0-2 mm). The average subsidence was similar to that in primary hip arthroplasty. The excellent long-term results of cemented collarless polished taper stems for primary and revision hip arthroplasty can be extended even further by cement-within-cement exchange, which preserves the femur.     

A Systematic Review and Meta-Analysis of Non-database Comparative Studies on Cemented Versus Uncemented Femoral Stems in Primary Elective Total Hip Arthroplasty

BackgroundCemented and uncemented femoral stems have shown excellent survivorship and outcomes in primary total hip arthroplasty (THA). Cementless stems have become increasingly common in the United States; however, multiple large database studies have suggested that elderly patients may have fewer complications with a cemented stem. As conclusions from large databases may be limited due to variations in data collection, this study investigated femoral stem survivorship and complication rates based on cement status in non-database studies.MethodsPreferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were utilized to identify articles for inclusion up until June 2021. Included articles directly compared outcomes and complications between patients undergoing primary THA without femoral stem cementing to those with cementing. Studies were excluded if they utilized large databases or consisted of patients with a preoperative diagnosis of trauma.ResultsOf the 1700 studies, 309 were selected for abstract review and nineteen for full-text review. A total of seven studies were selected. Meta-analyses indicated substantial heterogeneity between studies. There were no differences in revision rates (cementless: 5.53% vs. cemented 8.91%, P = .543), infection rates (cementless: 0.60% vs. cemented: 0.90%, P = .692), or periprosthetic fracture rates (cementless: 0.52% vs. cemented: 0.51%, P = .973) between groups.ConclusionThere is scarce literature comparing outcomes and complications between cemented and cementless femoral stems in primary elective THA without utilizing a database methodology. In our study, there were no differences in complications detected on meta-analyses. Given previous findings in database studies, additional high-quality cohort studies are required to determine if selected patients may benefit from a cemented femoral stem.     

Displacement of a Cemented Femoral Stem During Attempted Closed Reduction of a Dislocated Total Hip Arthroplasty

Displacement of a cemented femoral stem during attempted closed reduction of a dislocated total hip arthroplasty has been anecdotally described in the literature. All these reports involved use of cemented, highly polished, tapered stems. We report, the first to our knowledge, a case of displacement of a cemented, textured femoral stem, during attempted closed reduction. The case is being reported not only for its rarity but also to alert treating surgeons of this devastating complication which can expose the patient to the risks of open surgery. Gentle reduction, using the gravity method of Stimpson, under fluoroscopy control, may be safer and prevent this complication from occurring. If the cement mantle is intact, cement-within-cement is a reliable, quick, and simple technique to overcome this difficult problem.     

Periprosthetic Femoral Fracture Is a Leading Cause of Early Revision With Taper-Slip Stems in Primary Total Hip Arthroplasty: An Analysis of 2765 Total Hip Arthroplasties From a High-Volume Hospital

BackgroundIn 2016, the CPT stem replaced the Exeter stem as the main cemented stem at our institution. We assessed the prevalence of revision for periprosthetic femoral fracture (PFF) in patients operated on with either CPT or Exeter stem and compared the risk for revision between these stems.MethodsPrimary total hip arthroplasties either performed in 2012-2015 with Exeter stem (n = 1443) or in 2017-2018 with CPT stem (n = 1322) were included. The prevalence of revision for PFF was compared. The Kaplan-Meier estimated survivorships were calculated for the 2 stem designs. The risk for revision was analyzed using the Cox proportional hazard regression model.ResultsAt 2 years, PFF was the most common reason for revision in the study population (1.3% prevalence, comprising 35% of all revisions). Moreover, 1.6% (95% confidence interval [CI] 1.0-2.4) of the CPT and 1.0% (95% CI 0.6-1.6) of the Exeter stems had been revised due to PFF. The 3-year Kaplan-Meier probability estimates for all-cause revision were 4.8% for the CPT (95% CI 3.6-6.0) and 3.3% for the Exeter stem (95% CI 2.3-4.3). The hazard ratio for revision due to any reason was 1.1 (95% CI 0.3-3.8) during the first 2 weeks, and 1.8 (95% CI 1.2-2.7, P = .006) from 2 weeks onwards for the CPT compared with the Exeter stem.ConclusionThe considerable number of PFF revisions with taper-slip stems, especially with CPT stems, is a matter of concern. Alternative cemented stems should be considered in patients at high risk for PFF.     

Direct Anterior Approach for Primary Total Hip Arthroplasty Lowers the Risk of Dislocation Compared to the Posterior Approach: A Single Institution Experience

BackgroundOne purported benefit of the direct anterior approach (DAA) for total hip arthroplasty (THA) is a lower rate of postoperative dislocation.MethodsAn institutional database was used to identify 8840 primary THAs performed from 2003 to 2020 including 5065 (57%) performed using the DAA and 3775 (43%) performed via the posterior approach (PA). Direction and mechanism of dislocation were determined from chart review. Outcomes were compared using Kaplan-Meier survivorship with dislocation as the endpoint and a Cox multivariate regression was used to investigate factors associated with dislocation. The mean follow-up was 1.7 ± 2.0 years for the DAA and 3.1 ± 3.3 years for the PA.ResultsThe 0.5% (26/5065) incidence of dislocation among DAA hips was significantly less than the 3.3% (126/3775) among PA cases (P < .001). The majority of dislocations were posterior (DAA 57%, PA 79%) and occurred during activities of daily living (DAA 82%, PA 77%). Five-year survivorship was significantly higher for the DAA group compared to the PA group (99.1% vs 95.4%, P < .001). Dislocation risk was 4.9 times higher for the PA compared to the DAA (hazard ratio = 4.9, 95% confidence interval = 3.2-7.5, P < .001). Increasing head diameter reduced the risk (hazard ratio = 0.70, 95% confidence interval = 0.57-0.86, P < .001). The 0.2% incidence (10/5065) of revision for instability among the DAA group was significantly lower than the 1.1% (43/3775) rate for the PA group (P < .001).ConclusionCompared to primary THAs performed with the PA, DAA cases had a lower risk of dislocation, higher survivorship with dislocation as an endpoint, and a lower risk of revision for instability in this single institution cohort.