Total Hip Arthroplasty Dislocation Research Articles

Effectiveness of a bandage to prevent re-dislocation after total hip arthroplasty in patients with a previous hip dislocation. A randomized controlled trial with 12-week follow-up

Objective To investigate if using a hip bandage is more effective than standard care in the prevention of total hip arthroplasty re-dislocation in patients with a previous total hip arthroplasty dislocation. Design randomized controlled trial Setting Holstebro Regional Hospital and Viborg Regional Hospital Subjects A total of 99 patients, 51 women, mean 70.7 (SD 9.9) years were enrolled in an un-blinded, clinical randomized controlled trial. Interventions Participants with at least one previous total hip arthroplasty dislocation were randomized to either wearing a bandage reducing flexion, adduction, and internal rotation of the hip (intervention group) or to standard care (control group). The participants were followed for 12 weeks. Main follow-up measures were as follows: number of re-dislocations (primary outcome), hip disability measured with the Oxford Hip Score (0–48, 48 best), quality of life measured with the 36-Item Short Form Survey (0–100, 100 best), satisfaction with treatment and serious adverse events. Statistical analyses followed the intention-to-treat principle. Results No significant group differences were observed for the primary outcome re-dislocations (9 versus 15, P = 0.143) or for disability (11.3 versus 14.4, P = 0.161), quality of life (57.7 versus 48.3, P = 0.050) or satisfaction with treatment (P = 0.562). There were 3 serious adverse events leading to total hip arthroplasty revision in the intervention group and 4 in the control group. Conclusion We found that a hip bandage is not superior to standard care in the prevention of total hip arthroplasty re-dislocation in those with a previous total hip arthroplasty dislocation.

Stability in Direct Lateral vs Direct Anterior Total Hip Arthroplasty in the Context of Lumbar Spinal Fusion.

Lumbar spinal fusion (LSF) may increase the risk of dislocation in patients who have undergone total hip arthroplasty (THA), especially when the LSF was done before the THA. Most publications evaluated patients who had undergone THA using a posterior approach to the hip, yet there are little data on the influence of other surgical approaches. The goal of this study was to evaluate the risk of THA dislocation with anterior supine-based surgical approaches to the hip in patients who have undergone surgical management of concurrent hip and spine pathology. Patients older than 18 years who underwent an LSF and THA using a supine approach-either direct anterior (DA) or direct lateral (DL)-between 2000 and 2018 were identified. Only standard bearings (28-32-36-40 mm) were used. The dislocation rate was determined in this cohort. A subsequent analysis was conducted, stratifying patients based on the order in which they received the LSF or THA. A total of 582 surgical hip-spine patients were retrospectively identified and included in the cohort. Of total, 332 patients (57.0%) received an LSF before the THA; 250 (43.0%) had the fusion after a primary hip replacement. There were 143 patients (24.6%) in the DA group and 439 (75.4%) in the DL group. Overall, there were five dislocations (0.9%) in the entire cohort. In patients with simultaneous degenerative hip and lumbar spine pathology, anterior supine-based approaches demonstrate a low (<1%) risk of instability. Given the small number of total dislocation events (n = 5), additional analysis is warranted to assess the effect of different anterior approaches (DA versus DL) or timing of lumbar spinal surgery (before or after THA). Level III.

SPINOPELVIC MOBILITY IN PATIENTS WITH HIP OSTEOARTHRITIS AND TOTAL HIP ARTHROPLASTY INDICATION.

ABSTRACTIntroduction: Reduction of spinopelvic mobility is associated with an increased dislocation of total hip arthroplasty (THA).Objective: To assess 1) spinopelvic mobility in patients with primary hip osteoarthritis and THA indication and 2) the influence of hip flexion contracture on spinopelvic mobility.Methods: Thirty adult patients with primary hip osteoarthritis and THA indication were evaluated using radiographic parameters (pelvic incidence, pelvic tilt, sacral slope, lumbar flexibility, and spinopelvic mobility).Results: Spinopelvic mobility ranged from 6.90 a 54.50° (mean 32.79 ± 11.42) and the group of patients with hip flexion contracture had higher mobility. Spinopelvic mobility was correlated with pelvic tilt as well as with lumbar flexibility.Conclusion: Around 13.4% of patients had spinopelvic mobility under 20° , indicating reduced spinopelvic mobility and risk of THA dislocation. Level of Evidence III, Retrospective Comparative Study.

A Case of Rapidly Destructive Coxarthrosis with Anterior Dislocation of Total Hip Arthroplasty 1 Month after Surgery

A Case of Rapidly Destructive Coxarthrosis with Anterior Dislocation of Total Hip Arthroplasty 1 Month after Surgery

A Multivariate Analysis to Predict Total Hip Arthroplasty Dislocation With Preoperative Diagnosis, Surgical Approach, Spinal Pathology, Cup Orientation, and Head Size.

There are several risk factors for dislocation after total hip arthroplasty (THA), but few studies include radiographic assessment of implants, with spine pathology and patient characteristics. This study estimates the rate of dislocation by patient gender, age, race/ethnicity, body mass index, Charlson Comorbidity Index, spine pathology, prior spine fusion, levels affected, radiographic Kellgren-Lawrence score of spine osteoarthritis, THA indication, surgical approach, and femoral head size. Seventy-six primary THA patients between January 2007 and 2020 with a dislocation were matched on age and gender to subjects without a known history of dislocation using a 2:1 allocation. Univariable and multivariable survival models that account for matched strata were used to estimate the rate of dislocation. Median follow-up of patients at risk for dislocation was 26.48 months (95% confidence interval [CI] 23.75-36.40). On multivariable analysis, patients with an indication other than primary osteoarthritis were 3.69 (95% CI 2.22-6.13, P < .001) times more likely to dislocate than those with osteoarthritis. Patients with a spine pathology were also nominally more likely to dislocate (hazard ratio 1.76, 95% CI 0.97-3.18, P= .06), and patients receiving a posterior surgical approach were 2.74 (95% CI 1.11-6.76, P= .03) times more likely than those receiving a non-posterior approach to dislocate. Patients with THA indication other than primary osteoarthritis and receiving a posterior surgical approach, and to a lesser degree spinal pathology, were identified as affecting the rate of dislocation. After correcting for other variables, femoral head size, cup orientation, and patient factors were not predictive. Level IV, case-control study.

Radiologic restoration inaccuracy increases postoperative dislocation in primary total hip arthroplasty: a retrospective study with propensity score matching.

Dislocation is a complicated process and associated with multivariate etiology and risk factors. The purpose of this study was to verify if radiologic restoration inaccuracy increases postoperative dislocation in primary total hip arthroplasty (THA) individually or synergistically. From 2017 to 2020, we identified 76 (1.9%) patients who suffered postoperative dislocations from 3926 THAs in our institution. After excluded patients with previously proven patient-related and implant-related risk factors, the remaining patients were used to match a 1:1 control patients who were without dislocation. The cup position (inclination and anteversion angles), hip offset (HO), leg length discrepancy (LLD), and abductor lever arm (ALA) were analyzed by univariate analyses and multivariate logistic regressions. Measurements on radiographs showed excellent interobserver agreement (intraclass correlation coefficient (ICC) 0.922-0.952) and intraobserver agreements (ICC 0.933-0.967). HO restoration inaccuracy (without ± 5mm) was associated with higher dislocation risk (OR 4.241 95% CI 1.440-12.492, P = 0.009). The restoration inaccuracy of the cup position, LLD, or ALA could not increase the dislocation risk individually. When combining the radiologic restoration inaccuracy factors, the HO + LLD restoration inaccuracy and HO + ALA restoration inaccuracy increased the odds of postoperative dislocation (OR 12.056, 95% CI 1.409-103.127, P = 0.023; OR 4.770, 95% CI 1.336-17.028, P = 0.016, respectively). Combining the four risk factors of cup safe zone, HO, LLD, and ALA, patients with 3 or 4 radiologic restoration inaccuracy factors showed a higher risk of dislocation (OR 13.500, 95% CI 1.340-135.983, P = 0.027). Hip offset (HO) restoration inaccuracy increased the risk of dislocation following primary THA. Multivariate radiologic restoration accuracy is critical for the prevention of dislocation and needs to be valued by surgeons.

Integrating the Combined Sagittal Index Reduces the Risk of Dislocation Following Total Hip Replacement.

The aims of this matched cohort study were to (1) assess differences in spinopelvic characteristics between patients who sustained a dislocation after total hip arthroplasty (THA) and a control group without a dislocation, (2) identify spinopelvic characteristics associated with the risk of dislocation, and (3) propose an algorithm including individual spinopelvic characteristics to define an optimized cup orientation target to minimize dislocation risk. Fifty patients with a history of THA dislocation (29 posterior and 21 anterior dislocations) were matched for age, sex, body mass index (BMI), index diagnosis, surgical approach, and femoral head size with 200 controls. All patients underwent detailed quasi-static radiographic evaluations of the coronal (offset, center of rotation, and cup inclination/anteversion) and sagittal (pelvic tilt [PT], sacral slope [SS], pelvic incidence [PI], lumbar lordosis [LL], pelvic-femoral angle [PFA], and cup anteinclination [AI]) reconstructions. The spinopelvic balance (PI - LL), combined sagittal index (CSI = PFA + cup AI), and Hip-User Index were determined. Parameters were compared between the control and dislocation groups (2-group analysis) and between the controls and 2 dislocation groups identified according to the direction of the dislocation (3-group analysis). Important thresholds were determined from receiver operating characteristic (ROC) curve analyses and the mean values of the control group; thresholds were expanded incrementally in conjunction with running-hypothesis tests. There were no coronal differences, other than cup anteversion, between groups. However, most sagittal parameters (LL, PT, CSI, PI - LL, and Hip-User Index) differed significantly. The 3 strongest predictors of instability were PI - LL >10° (sensitivity of 70% and specificity of 65% for instability regardless of direction), CSIstanding of <216° (posterior instability), and CSIstanding of >244° (anterior instability). A CSI that was not between 205° and 245° on the standing radiograph (CSIstanding) was associated with a significantly increased dislocation risk (odds ratio [OR]: 4.2; 95% confidence interval [CI]: 2.2 to 8.2; p < 0.001). In patients with an unbalanced and/or rigid lumbar spine, a CSIstanding that was not 215° to 235° was associated with a significantly increased dislocation risk (OR: 5.1; 95% CI: 1.8 to 14.9; p = 0.001). Spinopelvic imbalance (PI - LL >10°) determined from a preoperative standing lateral spinopelvic radiograph can be a useful screening tool, alerting surgeons that a patient is at increased dislocation risk. Measurement of the PFA preoperatively provides valuable information to determine the optimum cup orientation to aim for a CSIstanding of 205° to 245°, which is associated with a reduced dislocation risk. For patients at increased dislocation risk due to spinopelvic imbalance (PI - LL >10°), the range for the optimum CSI is narrower. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Is Dislocation Risk due to Posterior Pelvic Tilt Reduced With Direct Anterior Approach Total Hip Arthroplasty?

Pelvic tilt affects acetabular anteversion, and thus total hip arthroplasty (THA) dislocation risk. The pubic symphysis-sacrococcygeal distance (PSCD) is an indicator of pelvic tilt, and a PSCD < 0 mm (ie, excessive posterior pelvic tilt) is associated with a 3.7-fold increase in postoperative dislocation rate. However, it is not known if the direct anterior (DA) approach might reduce this dislocation rate, specifically in high-risk populations such as negative PSCD. Standing anteroposterior radiographs were reviewed for 510 consecutive DA THAs to determine PSCD. Patients were separated into 2 groups: (1) PSCD > 0 mm (PSCD[+]) and (2) PSCD < 0 mm (PSCD[-]). Incidence of dislocation was determined. We recorded if patients had spinal deformity or lumbar fusion. Continuous variables were analyzed using Student's t-test, categorical variables were analyzed using Fisher's exact test, and a sample size calculation was performed. Three hundred fifty-eight hips (70.2%) were PSCD[+], while 152 hips (29.8%) were PSCD[-]. Three dislocations (3/510 hips, 0.6%) occurred. Two dislocators were in the PSCD[-] group (2/152 hips, 1.3%) and 1 dislocator was in the PSCD[+] group (1/358 hips, 0.3%) (P= .21). Twenty-four patients had degenerative scoliosis (24/510, 4.7%), of which 1 had a dislocation (1/24, 4.2%); 2 dislocations occurred in nonscoliosis patients (2/486, 0.4%) (P= .134). Twenty-seven patients had lumbar spinal fusion (27/510, 5.3%), of which there were no dislocations (0/27, 0.0%); all dislocations were in nonfusion patients (3/483, 0.6%) (P= 1.0). We demonstrate no increased risk for THA dislocation in patients with a PSCD < 0 mm who have undergone a DA approach. These data would suggest a protective effect of the DA approach against dislocation, even in historically high-risk populations.

Pelvic incidence affects postoperative dislocation rate in total hip arthropalsty patients with spinal fusion.

The purpose of this study was to compare the clinical outcome of total hip arthroplasty (THA) with and without spinal fusion (SF), and to evaluate the radiographic characteristics of patients with dislocation after THA. A case-controlled study of 53 patients (67 hips) who underwent both THA and SF was performed. The control group was matched to the SF group by age, gender and body mass index, and 106 patients (134 hips) were selected. Hip function was evaluated using the Japanese Orthopaedic Association (JOA) hip score. In addition, the incidence rates of postoperative complications were determined. Radiograph evaluation included lateral inclination and anteversion of the acetabular component. We also analysed sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). The JOA hip score at final follow up was significantly poorer in the SF group compared to the control group. There were 5 cases of dislocations in the SF group and none in the control group. The anteversion of acetabular cup, PT, and PI were significantly higher in the SF group compare to the control group. In particular, the PI of patients with anterior dislocation were significantly higher compare to those of patients without dislocation. Our study showed that SF is a risk factor for a poorer clinical outcome and postoperative dislocation of THA. In addition, the abnormal value of PI may be a risk factor to predict dislocation after THA with SF.

Lumbar spinal fusion does not increase early dislocation risk in primary total hip arthroplasty through the direct anterior approach.

Patients with total hip arthroplasty (THA) and a concomitant lumbar spinal fusion (LSF) might have an increased incidence of revision surgery and postoperative complications such as early THA dislocation. The direct anterior approach (DAA) has gained popularity in THA due to its soft tissue-preserving nature and the relatively low dislocation risk. The purpose of the present study was to examine whether LSF patients undergoing minimally invasive THA through the DAA mighthave an increased risk of prosthetic-related complications compared to matched-control patients without a LSF. Patients who underwent THA through the DAA in our institution from January 2014 to December 2018 were identified. A total of 30 primary THA also underwent LSF within 3months from the initial operation. These patients were randomly matched (1:3) for sex, age, and body mass index with patients who underwent primary THA in our institution without a history of LSF (control group). Peri and postoperative complications, revisions, radiographic and clinical outcomes were assessed retrospectively. LSF patients who underwent THA through the DAA did not have an increased risk of prosthetic-related complications compared to matched-control subjects without a LSF (6.6% versus 4.4%, P < 0.05). The functional and radiological outcomes were similar between groups. LSF patients undergoing THA could benefit from the DAA similarly to patients without LSFand without increased rate of early THA dislocation. Although the complex interplay between the lumbar spine and hip in THA patients warrants further investigation, the outcomes of THA through the DAA in LSF patients appear promising. Retrospective case-control study, III.

The influence of bearing surfaces on revisions due to dislocations in total hip arthroplasty

IntroductionRecurrent dislocations are still the most frequent reason for revision in total hip arthroplasty (THA). The impact of bearing surfaces on dislocations is still controversial. We hypothesized that: (1) bearing surfaces influence the revisions due to dislocations; (2) ceramic-on-ceramic reduced the revisions for dislocations in adjusted models; (3) Delta-on-Delta bearings reduced the revisions for dislocations in comparison to surfaces with cross-linked polyethylene.Materials and methodsThe regional arthroplasty registry was enquired about bearing surfaces and revisions for dislocations and instability. Unadjusted and adjusted rates were provided, including sex, age (<65 years or ≥65 years), head diameter (≤28 mm or >28 mm; <36 mm or ≥36 mm) as variables. 44,065 THAs were included.ResultsThe rate of revisions for dislocations was significantly lower in ceramic-on-ceramic and metal-on-metal bearings (unadjusted rates). After adjusting for age, sex, and head size (36 and 28 mm), hard-on-hard bearings were protective (p < 0.05): ceramic-on-ceramic had a lower risk of revisions due to dislocation than ceramic-on-polyethylene (HR 1.6, 95% CI 1.2–2.2 p = 0.0009). The rate of revisions for dislocation was similar in bearings with cross-linked polyethylene and Delta-on-Delta articulations, in unadjusted and adjusted models.ConclusionBearings with conventional polyethylene were more predisposed to dislocations. Currently adopted bearings exerted no significant influence on revisions due to dislocations. These findings could be primarily related to wear, but due to the time distribution, soft tissue envelopes and surface tension may also play a role. Pre-clinical biomechanical evaluations and prospective matched cohort studies are required to draw definitive conclusions.

P96. Pelvic morphometry for the spine and hip surgeon: Pelvic incidence is correlated to sacro-acetabular angle

<h3>BACKGROUND CONTEXT</h3> Alterations in spinopelvic motion and position following spinopelvic fusion may lead to impingement, increased wear, and dislocation in total hip arthroplasty (THA). Pelvic morphometry is critical in determining appropriate spinal alignment and acetabular position. <h3>PURPOSE</h3> Understanding the relationship between pelvic and acetabular morphometry and changes in postoperative position may enable more synergy between cup placement and spinal fusion. <h3>STUDY DESIGN/SETTING</h3> Single center, retrospective, case series. <h3>PATIENT SAMPLE</h3> Consecutive sample of patients from a single institution. <h3>OUTCOME MEASURES</h3> Radiographic spinopelvic parameters. <h3>METHODS</h3> This was a retrospective study of adult patients following spinopelvic fusion between 2012 and 2020. Patients with neuromuscular disease, active infections, trauma or tumors were excluded. Demographic data and operative details were recorded. Pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), acetabular ante-inclination (AI) and sacro-acetabular angle (SAA) were measured. Similar to PI, SAA is a fixed morphometric parameter. Measurements were made on preoperative and most recent postoperative standing sagittal spine radiographs. Analysis was performed with paired t-test and linear regression. <h3>RESULTS</h3> A total of 124 patients met inclusion criteria with mean follow-up time 17.6 months. PI-LL mismatch improved postoperatively from 19.6° to 5.7° (P < 0.001) and PT decreased from 27° to 25° (P = 0.008). PI and SAA were correlated with a 1° increase in PI corresponding to a 0.6° increase in SAA (P < 0.001, R2 = 0.446). Preoperative and postoperative spinopelvic parameters were not correlated with preoperative or postoperative AI. However, regression analysis revealed a 1° increase in AI postoperatively was correlated with a 0.9° increase in PT (P < 0.001, R2 = 0.81) and 1.6° decrease in LL (P < 0.001, R2 = 0.54). <h3>CONCLUSIONS</h3> Radiographic morphometric measurements of the acetabulum and pelvis are closely related. Changes in pelvic tilt and lumbar lordosis to restore sagittal spine balance following spinopelvic fusion appear to be linked to changes in acetabular position. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Can we trust combined anteversion and Lewinnek safe zone to avoid hip prosthesis dislocation?

IntroductionDislocation is one of the most common complications after primary total hip arthroplasty (THA). Combined anteversion (CA) is currently considered one of the most important measures of stability for THA. Thus, the aim of this study is to determine the association between a correct CA after THA and hip prosthesis dislocation, and to analyze the reliability of the Lewinnek safe zone parameters. Material and methodsThis is a non-interventional retrospective study, carried out at a tertiary hospital in Spain. 2489 primary THA in 2147 patients between January 2008 and December 2014 were identified. Clinical, biological and radiographic data, including cup inclination and cup and femoral anteversion, were analyzed of all patients who developed a hip prosthesis dislocation. ResultsThirty-four patients met the eligibility criteria to be analyzed. In 73.5% (25/34) of cases, acetabular anteversion (AV) was correct, with a mean AV of 15.1° ± 9.4°. Femoral anteversion (FA) was considered correct only in 38.2% (13/34) of the dislocated THA, with a mean FA of 8.4° ± 17.2°. Sixteen of these 34 patients (47.0%) presented a correct CA, with a mean CA of 24.2° ± 21.0°. Nineteen hips (55.8%) were within the Lewinnek safe zone. Moreover, eleven patients (32.3%) developed a dislocation even though components were within the Lewinnek safe zone and presented a correct CA. ConclusionOur findings suggest that even when the THA components are positioned within a correct CA and in the Lewinnek safe zone, hip prosthesis dislocations can occur in a not inconsiderable percentage of the cases. Thus, further radiological and clinical analysis should be done to identify potential reasons for hip prosthesis dislocation.

Dual mobility cups associated with proximal femoral replacement in nontumoral indications: Results and complications

IntroductionReconstruction of extensive proximal femoral bone loss is a major challenge during total hip arthroplasty (THA). Proximal femoral replacement (PFR), initially used for bone tumors, is an alternative to allograft-prosthetic composite reconstruction. However, PFRs present a high complication rate, particularly related to dislocation. Moreover, dual mobility cups (DMCs) are effective in preventing dislocation, and no study has yet assessed their association with PFRs. Therefore, the aim of this study was to assess the dislocation and complication rates in THA using PFRs with DMCs. HypothesisThe use of a DMC decreases the dislocation rate associated with PFRs in nontumoral indications. MethodsFrom 2008 to 2017, 66 PFRs associated with a DMC (40 women, mean age=71 years [26–94]) were included in our total joint registry and retrospectively reviewed. The main indications were complex periprosthetic and pertrochanteric fractures (26 THAs, 40%), aseptic loosening (22 THAs, 33%) and periprosthetic joint infections (18 THAs, 27%). A single design of PFR implant was used (Global Modular Replacement System (GMRS), Stryker, Mahwah, NJ, USA) with an uncemented stem in 54 THAs (82%). ResultsEighteen complications (27%) were reported at a mean follow-up of 4.6 years [2–10]: 5 dislocations (7.5%), 9 periprosthetic joint infections (13.6%), 2 aseptic loosening (3%) and 2 femur fractures (3%). Overall survivorship at 5 years was 72% (95% CI: 58–82). Survivorship free from dislocation was 94% (95% CI: 85–98) at 1 year. The mean Harris Hip Score was 70±16.4 [26–100] at latest follow-up. ConclusionThe use of DMCs limits the risk of PFR dislocation, in comparison to other series in the literature that used large femoral heads, without compromising implant survivorship. In addition, DMCs make it possible to overcome the potential risks of mechanical failure associated with constrained acetabular components. Level of EvidenceIV; retrospective cohort.

Is there a problem with modular dual mobility acetabular components in revision total hip arthroplasty at mid-term follow-up?

Modular dual mobility (MDM) acetabular components are often used with the aim of reducing the risk of dislocation in revision total hip arthroplasty (THA). There is, however, little information in the literature about its use in this context. The aim of this study, therefore, was to evaluate the outcomes in a cohort of patients in whom MDM components were used at revision THA, with a mean follow-up of more than five years. Using the database of a single academic centre, 126 revision THAs in 117 patients using a single design of an MDM acetabular component were retrospectively reviewed. A total of 94 revision THAs in 88 patients with a mean follow-up of 5.5 years were included in the study. Survivorship was analyzed with the endpoints of dislocation, reoperation for dislocation, acetabular revision for aseptic loosening, and acetabular revision for any reason. The secondary endpoints were surgical complications and the radiological outcome. The overall rate of dislocation was 11%, with a six-year survival of 91%. Reoperation for dislocation was performed in seven patients (7%), with a six-year survival of 94%. The dislocations were early (at a mean of 33 days) in six patients, and late (at a mean of 4.3 years) in four patients. There were three intraprosthetic dissociations. An outer head diameter of ≥ 48 mm was associated with a lower risk of dislocation (p = 0.013). Lumbrosacral fusion was associated with increased dislocation (p = 0.004). Four revision THAs (4%) were further revised for aseptic acetabular loosening, and severe bone loss (Paprosky III) at the time of the initial revision was significantly associated with further revision for aseptic acetabular loosening (p = 0.008). Fourteen acetabular components (15%) were re-revised for infection, and a pre-revision diagnosis of reimplantation after periprosthetic joint infection (PJI) was associated with subsequent PJI (p < 0.001). Two THAs had visible metallic changes on the backside of the cobalt chromium liner. When using this MDM component in revision THA, at a mean follow-up of 5.5 years, there was a higher rate of dislocation (11%) than previously reported. The size of the outer bearing was related to the risk of dislocation. There was a low rate of aseptic acetabular loosening. Longer follow-up of this MDM component and evaluation of other designs are warranted. Cite this article: Bone Joint J2021;103-B(7 Supple B):66-72.

What Factors Reduce the Incidence of Early Dislocations in Aseptic Total Hip Revisions with Stem Retention?

AbstractIt is unclear which factors are the most important protectors for early postoperative dislocation in aseptic total hip arthroplasty (THA) revisions with stem retention. Therefore, we sought to determine what factors reduce the incidence of dislocations among these patients. Single institution retrospective review was made of 83 consecutive aseptic THA revisions of the head/liner and/or cup performed by five surgeons between 2017 and 2020. Periprosthetic infections and femoral component revisions were excluded. Demographics, preoperative diagnosis, revision type, surgical approach, use of dual mobility systems, length of stay, skin-to-skin time, transfusions, complications, and dislocations were assessed. Pearson correlation/logistic regression analyses were used to determine association/independent predictors of dislocation; α was set at 0.05. The overall dislocation rate was 12%. In Pearson correlation, only preoperative diagnosis (instability vs. other, −0.241, p = 0.028) and revision type (only liner vs. cup, −0.304, p = 0.005) were significantly associated with dislocations. In logistic regression, only preoperative diagnosis other than instability (odds ratio [OR] = 0.235, p = 0.038) and cup revision (OR = 0.130, p = 0.014) were found significant protectors against dislocation. Surgical approach and dual mobility systems were not independent predictors of dislocations (p = 0.184 and p = 0.083, respectively). Dislocation rates were significantly different between those cases that had the cup revised (4.0%) and those that did not (24.2%; p = 0.012). Preoperative diagnosis other than instability and cup revision seemed to be protective against early dislocation. Revision of the cup, in particular, seemed to be the most important factor to avoid dislocations while use of dual mobility liners per se did not significantly reduce that risk. The role of isolated liner exchanges in revision THA continues to evolve and should be reserved for appropriately selected patients.

Do hip-abduction braces work?—A biomechanical evaluation of a commercially available hip brace

IntroductionDislocations of the hip joint are a common and clinically relevant complication following total hip arthroplasty (THA). Hip-abduction braces are currently used following operative or non-operative treatment of THA dislocations to prevent re-dislocations. However, the clinical and biomechanical effectiveness of such braces is still controversial.Material and methodsA total of 30 volunteers were measured during standing and during sitting up and down from a chair task wearing a hip brace set at 70°, 90° or no hip flexion limitation. Range of motion of the hip joint was measured in all directions by an inertial sensor system. Further it has been evaluated if the range of motion would be reduced by the additional use of an arthrodesis cushion.ResultsThe use of a hip brace set up with flexion limitation did reduce hip ROM in all directions significantly compared to unhinged brace (p < 0.001–0.035). Performing the “sit down and stand-up task” the brace set up at 70° flexion limitation did reduce maximum hip flexion significantly (p = 0.008). However, in most cases the measured hip flexion angles were greater than the settings of the hip brace should have allowed. The additional use of a cushion can further limit hip motion while sitting up and down from a chair.ConclusionThis study has demonstrated that hip-abduction braces reduce hip range of motion. However, we also found that to achieve a flexion limitation of the hip to 90°, the hip brace should be set at a 70° hip flexion limitation.

A Comparison of Revision Rates for Dislocation and Aseptic Causes Between Dual Mobility and Large Femoral Head Bearings in Primary Total Hip Arthroplasty With Subanalysis by Acetabular Component Size: An Analysis of 106,163 Primary Total Hip Arthroplasties

BackgroundDual mobility (DM) and large femoral head bearings (≥36 mm) both decrease the risk of dislocation in total hip arthroplasty (THA). There is limited comparable data in primary THA. This study compared the revision rates for dislocation and aseptic causes between DM and large femoral heads and subanalyzed by acetabular component size. MethodsData from the Australian Orthopedic Association National Joint Replacement Registry were analyzed for patients undergoing primary THA for osteoarthritis from January 2008 (the year of first recorded DM use) to December 2019. All DM and large femoral head bearings were identified. The primary outcome measure was the cumulative percent revision (CPR) for dislocation and for all aseptic causes. The results were adjusted by age, sex, and femoral fixation. A subanalysis was performed stratifying acetabular component diameter <58 m and ≥58 mm. ResultsThere were 4942 DM and 101,221 large femoral head bearings recorded. There was no difference in the CPR for dislocation (HR = 0.69 (95% CI 0.42, 1.13), P = .138) or aseptic causes (HR = 0.91 (95% CI 0.70, 1.18), P = .457). When stratified by acetabular component size, DM reduced the CPR for dislocation in acetabular component diameter <58 mm (HR = 0.55 (95% CI 0.30, 1.00), P = .049). There was no difference for diameter ≥58 mm. There was no difference in aseptic revision when stratified by acetabular component diameter. ConclusionThere is no difference in revision rates for dislocation or aseptic causes between DM and large femoral heads in primary THA. When stratified by acetabular component size, DM reduces dislocation for acetabular component diameter <58 mm. Level of EvidenceLevel III.

Constrained liners revisited: favourable mid-term results in patients with high-risk of dislocation: technical considerations for the optimal outcome.

The outcomes of constrained liners (CLs) in total hip arthroplasty (THA) remain inconclusive. We evaluated the mid-term performance of CLs in a consecutive series of high-risk dislocation patients undergoing primary or revision THA performed by a single surgeon. The survival, dislocation rate, complications, and functional patients' scores were assessed. Surgical tips to enhance outcomes were reviewed. 45 patients who received the Trident Tripolar CL between 2010 to 2019 were retrospectively evaluated from Arthroplasty Registry Thessaloniki. There were 17 primary and 28 revision THAs. The primary indications for using CL were severe abductor insufficiency or comorbidities, increasing the dislocation risk in primary, and recurrent dislocation or abductor insufficiency in revision THAs. The mean patient's age was 68.5 (±14.5) years, and the mean follow-up 3.81 (±1.66) years. There were 2 dislocations and 1 deep infection in the revision group. For any reason, the cumulative 6-year survival rate was 93.3%, 100% for primary, and 89.3% for revision THAs. The mean overall CL survival was 76.3 months for any reason (95% CI, 68.1-84.5) and 80.5 months for dislocation (95% CI, 75.8-85.2). The mean postoperative functional scores were significantly improved (p < 0.001) at the latest follow-up. CLs can provide hip stability and durable fixation in selected low-demand patients with high-risk for dislocation after primary and revision THA at mid-term follow-up. Careful patient selection and the refined surgical technique aiming at the neutral liner position and considering the high CLs' offset relative to stem-neck impingement are necessary to maximise outcomes.

Excessive pelvic incidence related anterior dislocation of posterior-approached total hip arthroplasty. A rare case report

Excessive pelvic incidence related anterior dislocation of posterior-approached total hip arthroplasty. A rare case report