Total Hip Arthroplasty Dislocation Research Articles

Early Hip Dislocation Rate in a Consecutive Series of 1093 Primary Total Hip Arthroplasties Using Imageless Navigation

Purpose: Postoperative hip dislocation remains a major complication in total hip arthroplasty. Various studies have demonstrated that several factors influence dislocation. While computer-assisted navigation has been proposed to enhance component alignment, its impact on dislocation rates remains unclear. This study aimed to investigate the early dislocation incidence and associated risk factors in primary total hip arthroplasty (THA) using imageless navigation. Methods: A retrospective review of patients undergoing imageless-navigated THA between February 2013 and December 2022 was conducted. Inclusion criteria comprised primary THA with a minimum 6-month follow-up. Statistical analysis included univariate regression to identify dislocation risk factors. Results: A total of 1093 THAs were analyzed. Dislocation occurred in 16 cases (1.5%), six in elective procedures (0.76%), and 10 in femoral neck fracture (FNF) (3.28%). The univariate regression analysis revealed that FNF emerged as a significant risk factor (OR = 4.418, P = 0.004), while age, gender, femoral head size, and save zone cup placement of Lewinnek did not significantly affect dislocation rates. Conclusions: Navigation use showed a reduced rate of early dislocation. FNF is a factor associated with postoperative hip dislocation in primary THA.

Short-term primary and revision modular dual-mobility cup total hip arthroplasty outcomes in high-risk dislocation patients: a retrospective study

PurposeModular dual-mobility cups (MDMCs) have a lower risk for dislocation after total hip arthroplasty (THA). The primary aims of our study were to analyze implant survivorship and to determine complications, especially dislocation, and revision rates of primary THAs used for hip fracture patients and for revision THAs. Secondary aims were to evaluate mortality after MDMC surgery and to find out if introduction of MDMC at our institution (Kuopio University Hospital, Finland) have decreased dislocation rate.MethodsThis retrospective cohort study consisted of 101 MDMC patients who were consecutively operated at our institution between April 1, 2018 and June 30, 2020. The implant survival rate, complications and mortality were evaluated with minimum of 2-year follow-up. Finnish Hospital Discharge Register was used to find out yearly dislocation rates following THA at our institution.ResultsThe cumulative estimate implant survival after MDMC in the primary THA group was 97% at 2 years, and in the revision THA group, it was 90% at 2 years. Dislocation was a rare complication in the primary THA group (1.4%), while it was common in revision THA group (12.9%). The cumulative estimate for mortality after MDMC in the primary THA group was 13% at 2 years, and in the revision group, it was also 13% at 2 years. The yearly number of patients who had re-hospitalization period due to THA dislocation decreased 46% after implementation of MDMC.ConclusionShort-term survival and complication rates after MDMC were excellent after primary THA and moderate after revision THA. Implementation of MDMC THA for hip fracture patients seems to have effectively decrease dislocation rate during a short follow-up.

The "true" 1-year incidence of dislocation after primary total hip arthroplasty: validation of an algorithm identifying dislocations in the Danish National Patient Register based on 5,415 patients from the Danish Hip Arthroplasty Register.

Dislocations continue to be a serious complication after primary total hip arthroplasty (THA). Our primary aim was to report the "true" incidence of dislocations in Denmark and secondarily to validate a previously developed algorithm designed to identify THA dislocations in the updated version of the Danish National Patient Register (DNPR), based on data from the Danish Hip Arthroplasty Register (DHR). We included 5,415 primary THAs from the DHR performed from July 1 to December 31, 2019. Version 3 of the DNPR was launched in February 2019, and a combination of data from the DNPR and a comprehensive national review of 1,762 hospital contacts enabled us to identify every dislocation occurring during the 1st year after THA to determine the "true" 1-year incidence of dislocation. The results were presented as proportions with 95% confidence intervals (CI), and validation was performed by calculating sensitivity and predictive values. The "true" 1-year incidence of dislocation was 2.8% (CI 2.4-3.3). Of these, 37% suffered recurrent dislocations during the follow-up period. Between-hospital variation ranged from 0.0% to 9.6%. The algorithm demonstrated a sensitivity close to 95%, while maintaining a positive predictive value of above 94%. The "true" 1-year incidence of dislocation of 2.8% is comparable to earlier findings, and large variation among hospitals continues to be evident. We have proven the algorithm to be valid in the latest DNPR (version 3), enabling it to be employed as a new quality indicator in future annual DHR reports.

Fewer Dislocations After Total Hip Arthroplasty With Robotic Assistance or Fluoroscopic Guidance

BackgroundComputer navigation and robotic assistance may reduce total hip arthroplasty (THA) dislocations by improving the accuracy and precision of component positioning. We investigated dislocation rates for THAs using conventional techniques, robotic assistance, and computer navigation, while controlling for surgical approach, dual mobility (DM) use, and fluoroscopic guidance. MethodsWe reviewed 11,740 primary THAs performed between June 2016 and December 2022, including 5,873 conventional, 1,293 with robotic-arm assistance, and 4,574 with navigation. The approach was posterior in 6,580 (56.0%), anterior in 4,342 (37.0%), and lateral in 818 (7.0%). A DM was used in 10.4%. Fluoroscopy was used in 3,653 cases and only with the anterior approach. Multivariate analyses yielded odds ratios (OR) for dislocation and revision. Additional regression analyses for dislocation were performed for approach and DM. ResultsRaw dislocation rates were as follows: conventional 1.2%, robotic 0.4%, navigation 0.9%, anterior with fluoroscopy 0.4%, anterior without fluoroscopy 2.3%, posterior 1.3%, and lateral 0.5%. Upon multivariate analysis, use of robotics was found to be associated with significantly reduced dislocation risk compared to conventional (OR: 0.3), as did anterior (OR: 0.6) compared to posterior approach; navigation and lateral approach were not found to be associated with a significant reduction in risk. For the anterior approach, multivariate analysis demonstrated that fluoroscopy significantly reduced dislocation risk (OR: 0.1), while DM, robotics, and navigation were not significant. For the posterior approach, the dislocation risk was lower with robotics than with conventional (OR: 0.2); the use of navigation or DM did not demonstrate a significant reduction in risk. ConclusionsThe use of robotics was associated with a reduction in dislocations for this cohort overall. Further, fluoroscopy in the anterior approach and robotic assistance in the posterior approach were both associated with decreased dislocation risk. The role of imageless computer navigation and DM implants requires further study.

Total Hip Arthroplasty versus Hemiarthroplasty for the Treatment of Displaced Femoral Neck Fracture in Elderly

Abstract Background Displaced intracapsular hip fractures are most commonly treated using either total hip arthroplasty (THA) or hemiarthroplasty. Aim of the Work To review systematically studies about the use of Total hip arthroplasty Versus hemiarthoplasty in management of displaced femoral neck fracture in elderly. Patients and Methods We included randomized controlled trials, including cluster RCTs, controlled (non-randomized) clinical trials or cluster trials, prospective and retrospective comparative cohort studies, and case-control or nested case-control studies. We excluded cross-sectional studies, case series, and case reports. Search results were uploaded to systematic review management software and manually screened for eligibility to be included. PRISMA flowchart were produced based on the search results and the inclusion/exclusion criteria. Results In our study there was statistically significant increase in the incidence of Reoperation in total hip arthroplasty (3.5%) than hemiarthroplasty (2.3%) with p-value < 0.001. Regarding Dislocation, there was statistically significant increase in the incidence of Dislocation in total hip arthroplasty (3.2%) than hemiarthroplasty (1.7%) with p-value < 0.001. Regarding Infection there was statistically significant increase in the incidence of Infection in total hip arthroplasty (4.5%) than hemiarthroplasty (3.4%) with p- value < 0.001. Regarding General Complications including: (Pneumonia – DVT- Pulmonary embolism- Myocardial infarct- Cerebral vascular lesion- Acute kidney failure- life threatening complications there was statistically no significant difference in the incidence of General complications in hemiarthroplasty (5.5%) and total hip arthroplasty (5.4%) with p-value = 0.608. Conclusions The authors concluded that DMTHA offered a better functional outcome than BA with no significant complications or mortality, and there was no significant difference between DMTHA and BA in the rate of dislocation.

Dislocation of primary total hip arthroplasty: Analysis of risk factors and preventive options.

Total hip arthroplasty (THA) is one of the most successful elective operations in orthopedic surgery for improving pain and functional disability in patients with end-stage joint disease. However, dislocation continues to be a troublesome complication after THA, as it is a leading cause of revision and is associated with substantial social, health, and economic costs. It is a relatively rare, usually early occurrence that depends on both the patients' characteristics and the surgical aspects. The most recent and important finding is the special attention to be given preoperatively to spinopelvic mobility, which is closely related to the incidence of dislocation. Consequently, clinical and radiographic assessment of the lumbar spine is mandatory to identify an altered pelvic tilt that could suggest a different positioning of the cup. Lumbar spinal fusion is currently considered a risk factor for dislocation and revision regardless of whether it is performed prior to or after THA. Surgical options for its treatment and prevention include the use of prostheses with large diameter of femoral head size, dual mobility constructs, constrained liners, and modular neck stems.

Emergency Department closed reduction of dislocated THR: the REDDTHR Prospective Multi-centre Study.

Dislocation is a potentially devastating complication severely affecting outcomes post total hip arthroplasty (THR). We aimed to assess the efficacy and safety of closed reduction of a dislocated THR within the Emergency Department (ED). A prospective multi-centre study was conducted over a 1-year period from November 2020 to December 2021 within 10 hospitals based in the East of England. Collected data included patient demographics, agent used for sedation, hospital length of stay, implant type and discharge destination. Patients were analysed according to whether successful reduction was performed in the ED or not. The primary outcome was length of stay, with secondary outcomes including discharge destination and pain post-procedure. We studied 99 patients with an average age of 77.02 years, with 39 (39%) patients being male. 11 patients had revision hip replacements and 88 patients had primary THRs. 57 (57.6%) underwent closed reduction in the Emergency department, of which 44 (77.2%) were successful. Successful closed reduction was significantly associated with lower patient age (p = 0.02), lower American society of Anesthesiologists (ASA) score (p < 0.01) and use of propofol (p < 0.01). Patients who underwent successful ED closed reduction had a lower hospital stay than those that did not (1 vs. 3 days, p < 0.01), however there was no significant difference in discharge destination. When adopted, success following closed reduction is increased in younger patients with less comorbidities following use of propofol sedation. Following sedation, patients have a significantly shorter hospital stay. Increasing uptake of closed reduction of THR dislocation within the ED in suitable patients with evidence-based best practice protocols will maximise patient outcomes whilst allowing efficient resource utilisation.

Clinical effects of combined anteversion and offset on postoperative dislocation in total hip arthroplasty

BackgroundImplant impingement and soft tissue tension are factors involved in dislocation after total hip arthroplasty (THA). Combined anteversion (CA) has been used as an indicator for implant placement. However, optimal implant placement remains a challenge. Moreover, the effect of changes in offset on dislocation is still unclear. In this study, we aimed to clarify the effects of postoperative CA and pre- and postoperative changes in offset on dislocation.MethodsIncluded were patients who underwent primary cementless THA between 2013 and 2020. The mean values of CA and offset in the dislocation and non-dislocation groups were compared. The CA values within ± 10% of the recommended values were defined as good CA, and those outside the range were rated as poor CA. The dislocation rates were compared between the good and poor CA groups and between the groups with and without increased offset.ResultsA total of 283 hips were included. The mean values of CA in the dislocation and non-dislocation groups were significantly different (P < 0.05). The dislocation rate was significantly lower in the good CA group (P < 0.05). The dislocation rates in the groups with and without increased total offset were 0.5% and 4.3%, respectively (P = 0.004). There were no dislocations in patients with good CA and increased offset.ConclusionsThe dislocation rate was significantly lower when implants were placed within ± 10% of the recommended CA value. Our results suggest that dislocation can be avoided by placing the implant in the good CA range and considering the increase in total offset on the operative side.

Spinopelvic interactions in total hip arthroplasty: 295 patients followed for a minimum follow-up of 10 years.

Concurrent spinal pathology is frequent in patients undergoing total hip arthroplasty (THA). In this study we examined whether spinopelvic interactions affect THA outcomes at a minimum follow-up of 10 years. 295 patients with a mean age of 63.3 (range 56‒80) years receiving a THA between 2006 and 2009 were assessed. Of these, 195 had mild lumbar disc degeneration and 100 had advanced lumbar spondylosis. We analysed the changes in the Harris Hip Score (HHS) and the survival rate for postoperative low back pain (LBP) and dislocation. Changes in acetabular component position, sacro-femoral-pubic (SFP) and pelvic obliquity (PO) angles were assessed with radiological images. The mean HHS was lower in female patients (p = 0.009), patients >65 years of age (p < 0.001) and those with advanced lumbar spondylosis (p = 0.002). 52 (71.2%) of the patients reporting preoperative LBP experienced improvement after THA while 47 (21.1%) of those without preoperative LBP postoperatively reported new onset LBP. Female patients (p = 0.025; hazard ratio [HR]: 1.831; 95% CI, 1.081-3.101) and those with preoperative LBP (p = 0.007; HR 2.068; 95% CI, 1.221-3.504) were at a higher risk of developing postoperative LBP at 10 years. 4 out of 9 THA dislocations were late and had shown decreasing SFP angle values over time. Acetabular component inclination and anteversion angles increased over time, whereas the SFP angle was associated with sex and age and the PO angle with age and the severity of any preoperative lumbar degeneration. Concurrent spinal pathology influences THA outcomes at a minimum follow-up of 10 years. Sex, age, and associated lumbar degeneration can affect clinical and radiological changes over time. A decrease in SFP angle values over time was found in patients sustaining late dislocation.

Prevalence of total joint arthroplasty in the adult spine deformity population.

The spine, hip, and knee are anatomically and biomechanically connected. Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are commonly employed to treat degenerative changes in the hip and knee, while fusion is used for spine degeneration. Spine deformity correction results in changes in sagittal alignment and pelvic parameters, and patients with stiff spines have higher rates of THA dislocation and revision due to instability. The goal of this study was to determine the prevalence of total joint arthroplasty (TJA) in adult spinal deformity (ASD) patients at our institution. Following Institutional Review Board approval, we retrospectively reviewed a list of cases performed by the senior author from 4/2017 to 5/2021. Patients > 18years old undergoing preoperative evaluation for symptomatic lumbar degeneration or ASD were included. Patients < 18years old, those diagnosed with adolescent idiopathic scoliosis, and non-fusion cases were excluded. Perioperative full-length standing EOS images were examined for the presence or absence of THA, TKA, or both. Demographic data was collected from patient electronic medical records, and statistical analyses were completed. 572 consecutive cases were reviewed, and 322 were excluded. 250 cases (97M:153F) were included in the final analysis, with a mean age of 61.8 ± 11.2years. A total of 74 patients had a TJA (29.4%). THA was present in 41 patients (16.4%), and TKA was present in 49 patients (19.6%). Males had a higher prevalence of TJA, THA, and TKA (29.9%, 16.5%, and 21.6%) than females (29.4%, 16.3%, and 18.3%). This study revealed a high prevalence TJA rate of 29.4% in ASD at our institution. This rate surpasses the prevalence rate reported among the general population in previous studies. High prevalence of patients with ASD and TJA may merit special surgical consideration.

Intraprosthetic Dislocation of Dual-Mobility Total Hip Arthroplasty: Analysis of a Case Series and Review of Literature

Intraprosthetic Dislocation of Dual-Mobility Total Hip Arthroplasty: Analysis of a Case Series and Review of Literature

Combining inertial navigation with transacetabular ligament in total hip arthroplasty via direct anterior approach results in excellent accuracy compared to standard manual technique - A retrospective cohort study.

Correct acetabular component placement plays a critical role in reducing early revisions after dislocations in total hip arthroplasty (THA). Although the transverse acetabular ligament (TAL) guides anteversion, inclination can only be accurately guided by navigation. In order to overcome the initial disadvantages with navigation, an imageless, easy-to-use inertial navigation system has been recently introduced. This study aims to analyze the accuracy of inclination with this navigation system compared to the standard manual technique. Two cohorts, manual technique (MT) and navigation (NAV) cohorts, consisted of 83 and 95 patients, respectively, after exclusion criteria were applied. Inclination target was 38° and anteversion was guided by TAL. Demographic data were collected, and anteroposterior (AP) pelvic and cross-table lateral radiographs were obtained 6 weeks post-operatively. Inclination and anteversion were determined on the AP pelvic and cross-table lateral radiograph, respectively. A mean inclination of 41.8° (±6.8°) and 38.9° (±4.4°) was found in the MT and NAV cohorts, respectively. There was no statistical difference in gender, age, and BMI. If the inclination was set within 10° of the target (i.e., 38°), 88% of the MT cohort and 97% of the NAV cohort were within the target zone. Accuracy decreased to 53% and 83%, respectively, if the target zone range was narrowed down to±5°. Combining inertial imageless navigation for inclination and TAL as a landmark for anteversion is significantly more accurate compared to the manual technique, without having the limitations and disadvantages of current standard navigational techniques.

Robotic-Arm Assisted Total Hip Arthroplasty: Workflow Optimization and Operative Times

Robotic-arm assisted total hip arthroplasty (RATHA) has been demonstrated to offer several benefits, such as increased accuracy in the placement of implants, improved patient outcomes and reduced complications such as dislocations in total hip arthroplasty. However, the potential increase in surgical time may sway some practitioners to hesitate adopting this technology, despite its benefits. Studies of RATHA learning curves have demonstrated that time neutrality can be achieved, but do not describe an efficient workflow. This paper lays out a process to achieve an optimal RATHA workflow and efficiencies in an ambulatory surgery center and presents timing data from 105 cases. We demonstrate that the learning curve for implementing RATHA can be navigated such that providers can offer the clinical benefits of RATHA to their patients without increasing operative or overall perioperative patient time.

Dislocation of Total Hip Arthroplasty of Femoral Neck Fracture in the Elderly: A Narrative Review.

Femoral neck fracture (FNF) is a common and devastating injury in the elderly population. The incidence of FNF is expected to increase in the future, particularly in the aging population.The displaced intracapsular FNFis replaced with a reconstruction prosthesis. These treatment options typically include hemiarthroplasty (HA) or total hip arthroplasty (THA). Dislocation after THA can be a significant complication, leading to increased hospital costs and patient dissatisfaction. This narrative review aims to investigate the potential risk factors for dislocation following THA after FNF. A systematic literature search was conducted, and 21 studies met the inclusion criteria. The studies included a total of 1703 patients who underwent THA after FNF. The majority of the patients were women, and the average age of participants was 76.2 years. The studies were primarily conducted by the orthopedic and traumatology departments. The surgical approach used for THA varied, with the anterior approach being associated with lower dislocation rates compared to the posterior approach. The analysis of surgical volume revealed that high-volume hospitals had lower dislocation rates compared to low-volume hospitals. Eight studies reported postoperative Harris Hip Scores (HHS), with higher HHS scores correlating with lower dislocation rates. Body mass index (BMI) was mentioned in 11 studies, and a normal BMI range was associated with lower dislocation rates compared to the overweight group. Rehabilitation protocols, particularly early initiation of physiotherapy, showed promising results in reducing dislocation rates. Additionally, the type of prosthesis used in the acetabulum was found to influence dislocation rates, with dual mobility cups demonstrating lower rates compared to single cups. In conclusion, several factors may contribute to the risk of dislocation following THA after FNF. These include the surgical approach, surgical volume, postoperative HHS scores, BMI, rehabilitation protocols, and the type of acetabular cup used. Further research is needed to better understand these risk factors and develop strategies to minimize dislocation rates and improve patient outcomes.

Usefulness of modular neck adapter in partial hip revision.

Modular neck adapters allow different length and offset changes to reach a stable total hip arthroplasty (THA) and permit a quick partial hip revision procedure without removing the existing components. The literature is poor on this matter and about the long-term related outcomes. This narrative review summarizes the most recent literature about these devices as an option of surgical treatment in partial total hip arthroplasty revision (THAr) focusing on indications, clinical and radiological outcomes, and related complications. The narrative review of the current available literature was conducted in December 2022 through electronic database. The terms used were: "Head neck taper" OR "Merete BioBall" AND "revision Total Hip Arthroplasty (MeSH Terms)". The timeframe was limited between 01/01/2000 and 01/12/2022. The studies regarding the clinical use of the Merete BioBall® system in hip revision surgery were included, while all the papers concerning modular stem prosthesis were excluded. The surgical procedure is safe, quick and allows the surgeon to correct a well-fixed stem version, length and offset, besides retensioning soft tissues. Clinical and radiological outcomes are good with low complications rates. The modular neck adapter system seems to be a good surgical procedure for recurrent dislocation of THA, especially in case of a second THAr surgery. However, the main indication of adapter use remains the isolated acetabular cup revision. The related complications are rare: the worst is the re-dislocation due to an insufficient stem version and length correction. Re-dislocation rates reported in literature vary from 5.2% to 15%. Corrosion or fretting of the modular system are not reported in literature.

Are Synovial Inflammatory Markers Increased in Patients Who Have Aseptic Total Hip Arthroplasty Dislocation Indicated for Revision?

BackgroundPrevious studies have speculated on elevated synovial inflammatory markers in patients undergoing surgical revision for total hip arthroplasty (THA) dislocation. However, this assumption is based on small patient series and a full investigation according to International Consensus Meeting (ICM) criteria has not yet been performed. MethodsPatients who had aseptic THA dislocation indicated for revision surgery were identified retrospectively. Only patients who had available diagnostic workup according to ICM 2018 criteria, including preoperative and intraoperative parameters, were included. For comparison, we analyzed a matched cohort of patients indicated for aseptic THA revision for other conditions. The 2 cohorts each consisted of 55 patients and were not different regarding age, sex, BMI, or implant fixation. ResultsThere was no difference in synovial white blood cell count (2,238 ± 2,544 versus 2,533 ± 3,448 c/μL; P = .601), alpha-defensin quotient (0.14 ± 0.11 versus 0.19 ± 0.28; P = .207), or polymorphonuclear neutrophil percentage (% PMN) (36.7 ± 22.6 versus 31.3 ± 24.5%; P = .312) between the groups. In the dislocation cohort, 20% of patients had a synovial white blood cell count of 3,000 c/μL or higher, compared with 18% in the control cohort. However, all patients in the dislocation cohort were below the cutoff for alpha-defensin or % PMN. ConclusionIn patients who have aseptic THA dislocation, synovial inflammatory markers are not elevated compared with patients undergoing aseptic revision for other complications. A detailed preoperative analysis of synovial inflammatory markers using ICM criteria appears critical in patients who have a THA dislocation to exclude periprosthetic joint infection. Level of EvidenceLevel III, retrospective, comparative study.

Mid-Term Outcomes of Modular Dual Mobility Bearings in Total Hip Arthroplasty

AbstractModular dual mobility (MDM) prostheses in which a cobalt–chromium liner is inserted into a titanium acetabular shell have the potential for corrosion. This has raised concern. While these constructs have been shown to effectively reduce the risk of dislocation in revision and high-risk primary total hip arthroplasty (THA), previous studies have been limited by the length of follow-up. The purpose of the study is to review the mid-term clinical outcomes of MDM implants with a minimum of 5-year follow-up. A retrospective, observational study was conducted on all consecutive patients who underwent THA with a MDM implant from June 2011 and March 2017 at an urban, tertiary academic medical center. Descriptive statistics were used to describe baseline patient characteristics. Primary endpoints included revision rates, dislocations rates, and implant component survivorship. Implant survival was analyzed using the Kaplan–Meier method. A total of 92 cases (61 primary, 31 revision) underwent THA with a MDM implant at an average follow-up of 6.90 ± 1.48 years (range: 5.01–10.53 years). The mean patient age at the time of surgery was 58.20 ± 11.85 years. Six patients were revised (6.5%, 6/92), two for periprosthetic joint infection (2.2%, 2/92), one due to aseptic loosening (1.1%, 1/92), one due to periprosthetic fracture (1.1%, 1/92), and the remaining two for metallosis (2.2%, 2/92). Kaplan–Meier survivorship analysis showed a 93.5% survival rate for all-cause revisions and 98.9% survival for acetabular component revision. MDM components reliably decrease the risk of dislocation after THA. However, the occurrence of two revisions due to metallosis demonstrates the necessity for continued surveillance in this cohort. Larger trials with long-term follow-up may be required to further elucidate the long-term outcomes and performance of these bearings.

DUAL-MOBILITY BEARINGS ARE NO PANACEA IN REVISION TOTAL HIP ARTHROPLASTY FOR RECURRENT DISLOCATION: A SINGLE-CENTRE EXPERIENCE OF 100 UNSTABLE HIPS

Dual-mobility (DM) bearings are effective to mitigate dislocation in revision total hip arthroplasty (THA). However, data on its use for treating dislocation is scarce. Aim of this study was to compare DM bearings, standard bearings and constrained liner (CL) in revision THA for recurrent dislocation and to identify risk factors for re-dislocation.We reviewed 100 consecutive revision THAs performed for dislocation from 2012 and 2019. 45 hips (45%) received a DM construct, while 44 hips (44%) and 11 hips (11%) had a standard bearing and CL, respectively. Rates of re-dislocation, re-revision for dislocation and overall re-revision were compared. Radiographs were assessed for cup positioning, restoration of centre of rotation, leg length and offset. Risk factors for re-dislocation were determined by cox regression analysis. Modified Harris hip scores (mHHS) were calculated. Mean follow-up was 53 months (1 to 103).DM constructs were used more frequently in elderly patients (p=0.011) and hips with abductor deficiency (p&lt; 0.001). The re-dislocation rate was 11.1% for DM bearings compared with 15.9% for standard bearings and 18.2% for CL (p=0.732). Revision-free survival for DM constructs was 83% (95% CI 0.77 – 0.90) compared to 75% (95% CI 0.68 – 0.82) for standard articulations and 71% (95% CI 0.56 – 0.85) for CL (p=0.455). Younger age (HR 0.91; p=0.020), lower comorbidity (HR 0.42; p=0.031), smaller heads (HR 0.80; p=0.041) and cup retention (HR 8.23; p=0.022) were associated with re-dislocation. Radiological analysis did not reveal a relationship between restoration of hip geometry and re-dislocation. mHHS significantly improved from 43.8 points to 65.7 points (p&lt;0.001) with no differences among bearing types.Our findings suggest that DM bearings do not sufficiently prevent dislocation in revision THA for recurrent dislocation. Reconstruction of the abductor complex may play a key role to reduce the burden in these high-risk patients.

Combined Anteversion Threshold to Avoid Anterior Dislocation in Primary Total Hip Arthroplasty Performed Through the Direct Anterior Approach

BackgroundComponent malposition in total hip arthroplasty (THA) can lead to dislocation, early implant failure, and revision surgery. As the surgical approach might affect the targeted combined anteversion (CA) of THA components, the present study aimed to evaluate the optimal CA threshold to avoid anterior dislocation in primary THA performed through a direct anterior approach (DAA). MethodsA total of 1,176 THAs in 1,147 consecutive patients (men: 593, women: 554) who had an average age of 63 years (range, 24 to 91) and a mean body mass index of 29 (range, 15 to 48) were identified. Medical records were reviewed for dislocation, whereas postoperative radiographs were assessed to measure the acetabular inclination and CA using a previously validated radiographic method. ResultsAn anterior dislocation occurred in 19 patients at an average of 40 days postoperatively. The average CA in patients who did and did not have a dislocation was 66 ± 8° and 45 ± 11°, respectively (P < .001). In 5 of 19 of the patients, a THA was performed for secondary osteoarthritis and 17 of 19 had a 28-mm femoral head. A CA ≥ 60° yielded a sensitivity of 93% and specificity of 90% for predicting an anterior dislocation in the present cohort. A CA ≥ 60° was associated with a significantly higher risk of anterior dislocation (odds ratio = 75.6; P < .001) compared to patients who had a CA<60 points. ConclusionThe optimal CA to avoid anterior dislocations in THA performed through the DAA should be less than 60°. Level of EvidenceCross-sectional study, Level III.

Evolution of Concepts: Can Personalized Hip Arthroplasty Improve Joint Stability?

Hip arthroplasty procedures are successful and reproducible. However, within the first two post-operative years, hip dislocations are the most common cause for revisions. This is despite the majority of the dislocations having the acetabular component within what is described as the 'safe zone'. The limitations of such boundaries do not take into account the variability of individual hip anatomy and functional pelvic orientation that exist. An alternative concept to address hip instability and improve overall outcomes is functional acetabular orientation. In this review article, we discuss the evolution of concepts, particularly the kinematic alignment technique for hip arthroplasty and the use of large-diameter heads to understand why total hip arthroplasty dislocations occur and how to prevent them.