High Risk Of Dislocation Research Articles

Association between disease activity of rheumatoid arthritis and risk of complications following total hip arthroplasty: a retrospective cohort study

BackgroundIdentifying rheumatoid arthritis patients at higher risk of complications after total hip arthroplasty could make perioperative management more effective. Here we examined whether disease activity is associated with risk of such complications.MethodsWe retrospectively analyzed data for 337 rheumatoid arthritis patients at our medical center who underwent primary total hip arthroplasty. Rheumatoid arthritis patients were categorized according to the simplified disease activity index (SDAI), the values of which at admission and follow-up were averaged together. Logistic regression was used to examine associations of mean SDAI with rates of dislocation, infection, periprosthetic fracture and aseptic loosening. As controls, 337 osteoarthritis patients who did not have systemic inflammation and who underwent the same procedure were matched across numerous clinicodemographic variables.ResultsAmong the 337 rheumatoid arthritis patients, 38 (11.3%) had postoperative complications, the rates of which varied significantly from 0 to 17.5% (p = 0.003) among the four subgroups whose disease activity based on mean SDAI was categorized as high, moderate, low or in remission. Each 1-unit increase in mean SDAI was associated with a significant increase in risk of postoperative complications (OR 1.015, 95% CI 1.001–1.029, p = 0.035). Across all rheumatoid arthritis patients, rate of complications did not differ significantly between patients who received disease-modifying anti-rheumatic drugs or other treatments. Rates of dislocation, of infection or of all postoperative complications combined were significantly lower among osteoarthritis controls than among rheumatoid arthritis patients.ConclusionGreater mean SDAI is associated with higher risk of dislocation, infection and composite postoperative complications after total hip arthroplasty in rheumatoid arthritis patients. These patients show a significantly higher rate of postoperative complications than osteoarthritis patients, likely reflecting the influence of systemic inflammation. Disease activity should be reduced as much as possible in rheumatoid arthritis patients before they undergo total hip arthroplasty.

Dual Mobility Cup in Total Hip Arthroplasty

Abstract Background Proximal femoral fractures are considered a common problem in the elderly. Osteoporosis and the risk of fall especially in old age add to the complexity of management of these types of fractures. These fractures can be managed with different types of implants e.g. Dynamic hip screw, proximal femoral nail, proximal femoral plate, etc.. Aim of the Work Prospective clinical trial study to assess the role of dual mobility unconstrained acetabular components in preventing and treating instability. Patients and Methods In the period between December 2014 to April 2017 a prospective study was conducted involving 25 patients with high risk of dislocation underwent total hip replacement using dual mobility cup either as primary hip arthroplasty or revision hip arthroplasty. All cases were operated upon in Ain Shams University Hospitals and the follow up of the cases was 1 year. Results There were no cases of prosthesis dislocation or loosening. There were only two cases of superficial wound infections who improved with wound debridement. Studies showed that the dual mobility cup did a great success in reduction in the risk of dislocation in specific conditions as patients with polio and other neuromuscular disorders and other risk factors for head dislocation. Conclusion Conversion of a failed implant to a total hip implant is a good and safe option in treatment of such cases. Dual mobility cups decreased the risk of dislocation in such cases with increased longevity of the prosthesis and a considerably accepted range of motion of the hip joint.

Monobloc dual-mobility acetabular component versus a standard single-mobility acetabular component.

The benefit of a dual-mobility acetabular component (DMC) for primary total hip arthroplasties (THAs) is controversial. This study aimed to compare the dislocation and complication rates when using a DMC compared to single-mobility (SM) acetabular component in primary elective THA using data collected at a single centre, and compare the revision rates and survival outcomes in these two groups. Between 2010 and 2019, 2,075 primary THAs using either a cementless DM or SM acetabular component were included. Indications for DMC were patients aged older than 70 years or with high risk of dislocation. All other patients received a SM acetabular component. Exclusion criteria were cemented implants, patients treated for femoral neck fracture, and follow-up of less than one year. In total, 1,940 THAs were analyzed: 1,149 DMC (59.2%) and 791 SM (40.8%). The mean age was 73 years (SD 9.2) in the DMC group and 57 years (SD 12) in the SM group. Complications and revisions have been analyzed retrospectively. The mean follow-up was 41.9 months (SD 14; 12 to 134). There were significantly fewer dislocations in the DMC group (n = 2; 0.17%) compared to the SM group (n = 8; 1%) (p = 0.019). The femoral head size did not influence the dislocation rate in the SM group (p = 0.702). The overall complication rate in the DMC group was 5.1% (n = 59) and in the SM group was 6.7% (n = 53); these were not statistically different (p = 0.214). No specific complications were attributed to the use of DMCs. In the DMC group, 18 THAs (1.6%) were revised versus 15 THAs in the SM group (1.9%) (p = 0.709). There was no statistical difference for any cause of revisions in both groups. The acetabular component aseptic revision-free survival rates at five years were 98% in the DMC group and 97.3% in the SM group (p = 0.780). The use of a monobloc DMC had a lower risk of dislocation in a high-risk population than SM component in a low-risk population at the mid-term follow-up. There was no significant risk of component-specific complications or revisions with DMCs in this large cohort.

The impact of femoral head size on the wear evolution at contacting surfaces of total hip prostheses: A finite element analysis

Total Hip Arthroplasty has been a revolutionary technique in restoring mobility to patients with damaged hip joints. The introduction of modular components of the hip prosthesis allowed for bespoke solutions based on the requirements of the patient. The femoral stem is designed with a conical trunnion to allow for assembly of different femoral head sizes based on surgical requirements. The femoral head diameters for a metal-on-polyethylene hip prosthesis have typically ranged between 22 mm and 36 mm and are typically manufactured using Cobalt–Chromium alloy. A smaller femoral head diameter is associated with lower wear of the polyethylene, however, there is a higher risk of dislocation. In this study, a finite element model of a standard commercial hip arthroplasty prosthesis was modelled with femoral head diameters ranging from 22 mm to 36 mm to investigate the wear evolution and material loss at both contacting surfaces (acetabular cup and femoral stem trunnion). The finite element model, coupled with a validated in-house wear algorithm modelled a human walking for 10 million steps. The results have shown that as the femoral head size increased, the amount of wear on all contacting surfaces increased. As the femoral head diameter increased from 22 mm to 36 mm, the highly cross-linked polyethylene (XLPE) volumetric wear increased by 61% from 98.6 mm3 to 159.5 mm3 while the femoral head taper surface volumetric wear increased by 21% from 4.18 mm3 to 4.95 mm3. This study has provided an insight into the amount of increased wear as the femoral head size increased which can highlight the life span of these prostheses in the human body.

Insufficient stem antetorsion and lower cup abduction is a combined risk factor for posterior hip dislocation in patients undergoing THA for femoral neck fractures: a retrospective analysis

BackgroundThe role of acetabular and femoral component positions with respect to the risk of post-operative instability and dislocation remains debated. In this study, we aimed to identify potential risk factors for early dislocation following primary total hip arthroplasty (THA) for displaced intracapsular femoral neck fractures (FNF) using radiological measurements.MethodsWe retrospectively analyzed data for patients who underwent cementless primary THA for FNF using a posterolateral approach between January 2018 and December 2021. Follow-up duration, age, sex, affected side, and mean time from THA to dislocation were recorded. Leg-length inequality, abductor lever arm, vertical and horizontal femoral offsets, vertical and horizontal hip centers of rotation, abduction, anteversion of the acetabulum and femoral prosthesis, and combined anteversion were measured.ResultsThe study sample included 17 men and 34 women, with 21 and 30 patients undergoing left- and right-hip operations, respectively. The mean patient age was 70.18 ± 7.64 years, and the mean follow-up duration was 27.73 ± 13.52 months. The mean time between THA and dislocation was 1.58 ± 0.79 months. Seven patients (13.73%) sustained posterior dislocation of the hip. The abduction angle (36.05 ± 6.82° vs. 45.68 ± 8.78°) (p = 0.008) and anteversion of the femoral prosthesis (8.26 ± 4.47° vs. 19.47 ± 9.01°) (p = 0.002) were significantly lower in the dislocation group than in the control group. There were no significant differences in other parameters.ConclusionsInsufficient stem antetorsion combined with lower abduction angle of the acetabular component were associated with a high risk of dislocation, especially in patients with deep flexion or internal rotation of the flexed hip joint and knees, or in patients with a stiff spine or anterior pelvic tilt, impingement may then occur in the neck of the prosthesis and cup component, ultimately resulting in posterior dislocation. These findings could remind surgeons to avoid simultaneous occurrence of both in THA surgery. These results provide new insight into risk factors for hip dislocation in patients undergoing primary THA for FNF and may aid in reducing the risk of instability and dislocation.Level of evidenceProspective comparative study Level II.

PERIPROSTHETIC HIP FRACTURES MANAGED BY REVISION ARTHROPLASTY

AbstractIntroductionIn general the life expectancy of population is improving. This is causing to increase case load of peri-prosthesis fractures after joint replacements. We present our results of peri-prosthesis fracture around hip managed by revision arthroplasty.MethodsA retrospective analysis of 24 consecutive patients of periprosthetic hip fracture treated with a revision arthroplasty at Major Trauma Centre between February 2021 and January 2022.Results12 male and 12 female patients, average age 78 years. 3 fractures around BHR prosthesis, 2 type A, 15 type B and 3 of type C (Vancouver). The surgery was done in an average 6 days after injury (range 1–14). 6 patients died in follow up, 1 patient contracted infection, 2 developed LLD and 1 patient had multiple dislocations. 6 patients had revision using endo-prosthesis. Advanced age with peri-prosthesis fracture has increased risk of mortality (average age 84.5 years).ConclusionEndo-prosthesis replacement had higher risk of dislocation, infection and mortality. Overall patients do well after a revision arthroplasty for periprosthetic hip fracture.Declaration of Interest(b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

912 An Evaluation of Outcomes in G7 Dual Mobility Cup Arthroplasty for Primary Total Hip Arthroplasty: A Single Centre Retrospective Study

Abstract Background Hip instability is one of the commonest complications of total hip replacement (THR) and remains a leading indication for revision surgery. The G7 Dual Mobility Cup (G7-DMC) was designed to improve hip stability and increase range of movement. Our study aims to look at the use of G7-DMC in patients with varying risk of dislocation, to observe rates of hip instability, as well as their short and long term post-operative outcomes. Method Between 2017 and 2021, 177 patients received a G7-DMC for primary hip arthroplasty. These patients were divided into three groups: elective surgery with low risk for dislocation, elective surgery with high risk of dislocation or THR for trauma. Outcome measures included dislocation rate, Oxford Hip Score (OHS), short- and long-term complications and revision surgery. Results One traumatic dislocation (1.9%) was seen in the high-risk group following a fall in the post-operative period, no dislocations were seen in the low-risk or trauma groups. No patients required revision surgery for dislocation or hip instability. OHS was significantly lower in the high-risk group (39.4 +/- 8.9) compared with low-risk (43.5 +/- 6.5) (P = 0.012), however no significant difference was seen against the trauma group (41.5 +/- 7.8). Long-term complications were similar in all three groups. Conclusions Despite higher rates of short-term complications and poorer OHS seen in the high-risk group of patients, no spontaneous dislocation or revision surgery for hip instability has been seen in any of the three groups. We therefore support its use in primary THR, particularly in those with high risk of dislocation.

MONOBLOC DUAL MOBILITY CUP VERSUS LARGE FEMORAL HEADS: A COMPARATIVE STUDY OF 1,940 CONSECUTIVE PRIMARY TOTAL HIP ARTHROPLASTIES

The benefit of dual mobility cup (DMC) for primary total hip arthroplasties (THA) is still controversial. This study aimed to compare 1) the complications rate, 2) the revisions rate, 3) the survival rate after monobloc DMC compared to large femoral heads (LFH) in primary THA.Between 2010 and 2019, 2,075 primary THA using cementless DMC or LFH were included. Indications for DMC were patients older than 70 years old or with high risk of dislocation. Every other patient received a LFH. Exclusion criteria were cemented implants, femoral neck fracture, a follow-up of less than one year. 1,940 THA were analyzed: 1,149 DMC (59.2%), 791 LFH (40.8%). The mean age was 73 ±9.2 years old in DMC group and 57 ±12 in LFH group. The complications and the revisions have been assessed retrospectively.The mean follow-up was 41.9 months ±14 [12–134]. There were significantly fewer dislocations in DMC group (n=2; 0.17%) compared to LFH group (n=8; 1%) (p=0.019). The femoral head size had no impact on the dislocations rate in LFH group (p=0.70). The overall complication rate in DMC (n=59; 5.1%) and LFH (n=53; 6.7%) were not statistically different (p=0.21). No specific complication was attributed to the DMC. In DMC group, 18 THA (1.6%) were revised versus 15 THA in LFH group (1.9%) (p= 0.71). There was no statistical difference for any cause of revisions in both groups. The cup aseptic revision-free survival rates at 5 years were 98% in DMC group and 97.3% in LFH group (p=0.78).Monobloc DMC had a lower risk of dislocation in a high-risk population than LFH in a low-risk population at the mid-term follow-up. There was no significant risk of specific complications or revisions for DMC in a large cohort. Monobloc DMC can be safely used in a selected high-risk population.

A piriformis-preserving posterior approach reduces dislocation rate of the hemiarthroplasty in patients with femoral neck fracture

IntroductionThe posterior approach (PA) for hemiarthroplasty (HA) in patients with femoral neck fracture (FFN) has a high risk of dislocation; however, by preserving the piriformis muscle, the dislocation rate could be lowered considerably. The aim of this study was to compare the surgical complications of the piriformis-preserving posterior approach (PPPA) and the PA in patients with FNF treated with HA. MethodsOn 1 January 2019, the PPPA was introduced at two hospitals as the new treatment standard. The sample size was calculated based on a 5 percentage point dislocation reduction and 25% censoring; a sample of 264 patients per group was determined. An approximately 2-year inclusion period with 1-year follow-up was estimated, including a historical cohort from 2 years before the PPPA introduction. Data were retrieved from health care records and X-ray images from the hospitals’ administrative databases. Relative risk (RR) and 95% confidence intervals were calculated using Cox regression and adjusted for age, sex, comorbidity, smoking, surgeon experience and implant type. ResultsThere were 527 patients included in the study, of which 72% were women and 43% were above 85 years old. There were no baseline differences between the PPPA and PA groups in sex, age, comorbidity, body mass index, smoking, alcohol, mobility, length of surgery, blood loss or implant positioning, but there were differences in 30-day mortality, surgeon experience and implant type.The dislocation rate reduced from 11.6% in the PA group to 4.7% in the PPPA group (p = 0.004), with an RR of 2.5 (1.2; 5.1). The reoperation rate reduced from 6.8% with the PA to 3.3% with the PPPA (p = 0.022), with an RR of 2.1 (0.9; 5.2), and total surgery-related complications reduced from 14.7% with the PA to 6.9% with the PPPA (p = 0.003), with an RR of 2.4 (1.3; 4.4). InterpretationChanging from PA to PPPA in patients with FNF treated with HA resulted in a more than 50% reduction in dislocation and reoperation rates. This approach was easily introduced and may enable further lowering of dislocation rates through the sparing of all short external rotators.

Selective Use of Dual-Mobility Did Not Significantly Reduce 90-Day Readmissions or Reoperations After Total Hip Arthroplasty

BackgroundSelective use of dual mobility (DM) implants in total hip arthroplasty (THA) patients at high dislocation risk has been proposed. However, evidence-based utilization thresholds have not been defined. We explored whether surgeon-specific rates of DM utilization correlate with rates of readmission and reoperation for dislocation. MethodsWe retrospectively reviewed 14,818 primary THA procedures performed at a single institution between 2011 and 2021, including 14,310 fixed-bearing (FB) and 508 DM implant constructs. Outcomes including 90-day readmissions and reoperations were compared between patients who had FB and DM implants. Cases were then stratified into 3 groups based on the attending surgeon’s rate of DM utilization (≤ 1, 1 to 10, or > 10%) and outcomes were compared. ResultsThere were no differences in 90-day outcomes between FB and DM implant groups. Surgeon frequency of DM utilization ranged from 0% to 43%. There were 48 surgeons (73%) who used DM in ≤ 1% of cases, 11 (17%) in 1% to 10% of cases, and 7 (10%) in > 10% of cases. The 90-day rates of readmission (7.3% versus 7.6% versus 7.2%, P = .7) and reoperation (3.4% versus 3.9% versus 3.8%, P = .3), as well as readmission for instability (0.5% versus 0.6% versus 0.8%, P = .2) and reoperation for instability (0.5% versus 0.5% versus 0.8%, P = .6), did not statistically differ between cohorts. ConclusionSelective DM utilization did not reduce 90-day readmissions or reoperations following primary THA. Other dislocation-mitigation strategies (ie, surgical approach, computer navigation, robotic assistance, and large diameter FBs) may have masked any benefits of selective DM use.

JUMBO DUAL-MOBILITY CUP PROVIDES LOW RISK OF DISLOCATION IN REVISION TOTAL HIP ARTHROPLASTY

THA in patients with acetabular bone defects is associated with a high risk of dislocation. Dual mobility (DM) cups are known to prevent and treat chronic instability. The aim of this study was to evaluate the dislocation rate and survival of jumbo DM cups.This was a retrospective, continuous, multicenter study of all the cases of jumbo DM cup implantation between 2010 and 2017 in patients with acetabular bone loss (Paprosky 2A: 46%, 2B: 32%, 2C: 15% and 3A: 6%). The indications for implantation were revisions for aseptic loosening of the cup (n=45), aseptic loosening of the femoral stem (n=3), bipolar loosening (n=11), septic loosening (n=10), periprosthetic fracture (n=5), chronic dislocation (n=4), intraprosthetic dislocation (n=2), cup impingement (n=1), primary posttraumatic arthroplasty (n=8), and acetabular dysplasia (n=4). The jumbo cups used were COPTOS TH (SERF), which combines press-fit fixation with supplemental fixation (acetabular hook, two superior flanges with one to four screws, two acetabular pegs). A bone graft was added in 74 cases (80%). The clinical assessment consisted of the Harris hip score. The primary endpoint was surgical revision for aseptic acetabular loosening or the occurrence of a dislocation episode.In all, 93 patients were reviewed at a mean follow-up of 5.3 ± 2.3 years [0, 10]. As of the last follow-up, the acetabular cup had been changed in five cases: three due to aseptic loosening (3.2%) and two due to infection (2.1%). The survivorship free of aseptic loosening was 96.8%. Three patients (3%) suffered a dislocation. At the last follow-up visit, the mean HSS scores were 72.15, (p < 0.05).Use of a jumbo DM cup in cases of acetabular bone defects leads to satisfactory medium-term results with low dislocation and loosening rates.

The association of dual-mobility total hip arthroplasty with dislocation compared to conventional hip arthroplasty for neck of femur fracture

<abstract><sec> <title>Introduction</title> <p>Neck of femur fractures are extremely common worldwide and have a mortality rate of 15% at 1 year. Dual-mobility cups (DMCs) have demonstrated a reduction in dislocation and revision rates for elective total hip arthroplasty (THA) but the benefits of DMC use in neck of femur fractures are less clear. The aim of this study was to compare the rate of dislocation between conventional and DMC THA following neck of femur fracture.</p> </sec><sec> <title>Materials and methods</title> <p>Data was retrospectively collected for patients who received either DMCs or standard acetabular components for neck of femur fractures at our institution. Patients were excluded if they had less than 2 years follow-up. Dislocation and revision rates were collected for all patients in addition to radiographic analysis to assess for loosening.</p> </sec><sec> <title>Results</title> <p>Data was collected for 39 patients with DMCs and 95 patients with conventional THA. Two patients with DMCs suffered a dislocation (5.1%) compared to 7 patients (7.3%) who underwent a conventional THA (p = 0.49). Both patients in the DMC group had additional risk factors for dislocation. One DMC patient required revision surgery for dislocation and one conventional THA patient underwent a revision for aspetic loosening. There were no cases of radiographic loosening in the DMC group.</p> </sec><sec> <title>Conclusions</title> <p>Our study showed a trend towards lower dislocation rates in patients treated with a DMC compared to conventional THA. Although there are potential issues associated with DMC implants and cost implications, this study suggests they may be advantageous in patients at high risk for dislocation.</p> </sec></abstract>

THE CEMENTED DOUBLE MOBILITY CUP IN HIP REVISION: DIFFERENT POSSIBILITIES OF USE.

The aim of our work is to review those patients who underwent prosthetic hip revision surgery in our hospital considered to be patients at high risk of dislocation or recurrent dislocation, and who underwent a double mobility cemented cup (CMD). Analyzing the different ways to place these cups and the clinical results and reluxations. The 69 cases comprised 34 men and 35 women with a mean age of 77,39 years. The mean follow-up was 4.7536 years. The type of intervention performed varied according to the cause of the intervention, the acetabular bone stock and the state of the primary cup. In the cases in which there was a good fixation of the primary metalback, we opted to carry out a cementation of the cemented DMC into the existing well-fixed metal acetabular shell, this occurred in 23 cases. In the cases where there was loosening of the primary cup but there was a good bone stock, a CMD was cemented into the bone (21 cases). In the cases where there was a Paprosky type III we cemented a DMC to a Bursch-Schneider reinforcement ring together with the placement of a cancellous bone graft (25 cases). The clinical evaluation at the end of the follow-up, according to the MD Scale, showed the mean value was 16.454 (SD 0.79472), with a survival at the end of the follow-up of 100% of the placed DMC. The use of cemented DMC is a good solution in the replacement of THA, especially in cases of reluxation or risk of dislocation due to personal or technical predisposing factors. The use of these DMC cemented can be directly to the bone, into the existing well-fixed metal Shell, or cemented to a reinforcing ring, depending on the acetabular defect. Evidence Level III; Comparative Case Series .

Does the Dual Mobility Cup Reduce Dislocation After Primary Total Hip Arthroplasty in Elderly Patients at High Risk of Dislocation?

The dual mobility cup (DMC) is designed to extend the longevity of the prosthesis by improving stability, enhancing the range of motion, and decreasing impingement without increasing wear. We hypothesized that DMC would reduce the risk of dislocation in elderly patients. This study aimed to investigate the clinical and radiographic outcomes of DMC-total hip arthroplasty (THA) in elderly patients at high risk of dislocation. From June 2016 to March 2020, 94 patients with a mean age of 77.7 years (97 hips) who underwent a posterolateral approach for DMC-THA in our department were followed up for at least one year. Preoperative and postoperative pelvic tilt angles (PTA) and DMC orientation were prospectively collected for all patients. Intraoperative and postoperative complications were recorded. A parametric test was used for normal distribution, and a non-parametric test was used for non-normal distribution. Abduction and anteversion angles of the cup were 42.4 and 18.0° in the supine position immediately postoperative. The average PTA for patients in the supine and standing positions were 26.5 and 34.5°, respectively. When moving from the supine to the standing position, patients experienced a mean posterior pelvic tilt of 9°. No intraoperative acetabular-related complications were recorded. Postoperative complications included early infection in one patient (1.0%) and dislocation in one patient (1.0%). Our study demonstrates that DMC-THA provides satisfactory short-term outcomes in elderly patients at a high risk of dislocation, regardless of the change in PTA resulting from postural transition.

The Incidence and Temporal Trends of Dislocation After the Use of Constrained Acetabular Components and Dual Mobility Implants in Primary Total Hip Replacements: A Systematic Review and Meta-Analysis of Longitudinal Observational Studies.

Dislocation after a primary total hip replacement (pTHR) remains a common cause of treatment failure. Constrained acetabular components (CACs) and dual mobility implants (DMIs) may mitigate this in patients at high risk of dislocation or with significant intraoperative instability. This meta-analysis evaluated the incidence and temporal trends of dislocation after implantation with CACs and DMIs in pTHR. Longitudinal studies reporting dislocation after the use of CACs or DMIs in pTHR were sought from Medline and Embase to September 2020. Secondary outcomes included revision surgery for dislocation and for all causes. A total of 46 studies (3 CAC and 43 DMI) comprising 582 CACs and 18,748 DMIs were included. The pooled incidence of dislocation was 1.08% (95% confidence interval [CI]: 0.00-3.72; range 0.27%-2.60%) over a weighted mean follow-up of 4.1 years for CACs, compared with 0.25% (95% CI: 0.08-0.46; range 0.00%-4.72%) over 6.2 years for DMIs. For DMIs, there was a temporal decline in dislocations from the 1980s onward, and dislocation rates remained low (<1%) until 15 years postoperatively. There were insufficient data for similar analysis of CACs. All studies were at high risk of bias. The incidence of revision for dislocation after CACs was 0.3% vs 0.1% for DMIs, and the incidence of revision for all causes after CACs was 4.8% vs 2.7% for DMIs. DMIs demonstrated a lower incidence of dislocation compared with CACs; however, there was a relative absence of CACs used in the context of pTHR in the literature. Temporal trends in dislocation have improved over time for DMIs.

Creation of a Total Hip Arthroplasty Patient-Specific Dislocation Risk Calculator.

Many risk factors have been described for dislocation following total hip arthroplasty (THA), yet a patient-specific risk assessment tool remains elusive. The purpose of this study was to develop a high-dimensional, patient-specific risk-stratification nomogram that allows dynamic risk modification based on operative decisions. In this study, 29,349 THAs, including 21,978 primary and 7371 revision cases, performed between 1998 and 2018 were evaluated. During a mean 6-year follow-up, 1521 THAs were followed by a dislocation. Patients were characterized, through individual-chart review, according to non-modifiable factors (demographics, indication for THA, spine disease, prior spine surgery, and neurologic disease) and modifiable operative decisions (operative approach, femoral head diameter, and type of acetabular liner [standard, elevated, constrained, or dual-mobility]). Multivariable regression models and nomograms were developed with dislocation as a binary outcome at 1 year and 5 years postoperatively. Dislocation risk, based on patient-specific comorbidities and operative decisions, was wide-ranging-from 0.3% to 13% at 1 year and from 0.4% to 19% at 5 years after primary THA, and from 2% to 32% at 1 year and from 3% to 42% at 5 years after revision THA. In the primary-THA group, the direct anterior approach (hazard ratio [HR] = 0.27) and lateral approach (HR = 0.58) decreased the dislocation risk compared with the posterior approach. After adjusting for the approach in that group, the combination of a ≥36-mm-diameter femoral head and an elevated liner yielded the largest decrease in dislocation risk (HR = 0.28), followed by dual-mobility constructs (HR = 0.48). In the patients who underwent revision THA, the adjusted risk of dislocation was most markedly decreased by the use of a dual-mobility construct (HR = 0.40), followed by a ≥36-mm femoral head and an elevated liner (HR = 0.88). The adjusted risk of dislocation after revision THA was decreased by acetabular revision (HR = 0.58), irrespective of whether other components were revised. Our patient-specific dislocation risk calculator, which was strengthened by our use of a robust multivariable model that accounted for comorbidities associated with instability, demonstrated wide-ranging patient-specific risks based on comorbidity profiles. The resultant nomograms can be used as a screening tool to identify patients at high risk for dislocation following THA and to individualize operative decisions for evidence-based risk mitigation. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Evaluation of the rate of post-operative dislocation in patients with ipsilateral valgus knee deformity after primary total hip arthroplasty.

There is scant literature on the evaluation of dislocation after total hip arthroplasty (THA) in patients with ipsilateral valgus knee deformity. This study aimed to investigate the post-operative dislocation rate in patients with valgus knee deformity who underwent ipsilateral THA and identify whether ipsilateral valgus knee deformity increases the dislocation rate after THA. We retrospectively reviewed patients with valgus knee deformity who underwent ipsilateral THA in our institution from January 2016 to December 2018. Each hip with ipsilateral valgus knee deformity was matched with a hip without valgus knee deformity according to sex, affected side, and date of surgery. The primary outcome was the dislocation rate after THA. Univariate analyses were initially used to compare data between the dislocation group and the non-dislocation group. Independent risk factors for dislocation were determined using multivariate logistic regression. There were 257 THAs with ipsilateral valgus knee deformity (valgus knee group) and 257 THAs without valgus knee deformity (control group). The valgus knee group showed a significantly higher dislocation rate than the control group (9.7% versus 1.6%, p < 0.001). Older age (p = 0.020) and malposition of the acetabular cup (p = 0.048) were independent risk factors of post-operative dislocation. Patients with valgus knee deformity have a higher risk of dislocation after ipsilateral THA. If ipsilateral THA and total knee arthroplasty must be performed successively, total knee arthroplasty may have an earlier priority than THA.

The Impact of Lumbar Spine Disease on Hip-Spine Relationship in Total Hip Arthroplasty: A Mini-Review

Background: Patients with severe lumbar spine diseases run a high risk of dislocation after total hip arthroplasty. Therefore, it is essential to determine the pathological effect of common lumbar diseases on pelvic motions before the surgery. Aim: This study reviewed the literature on the hip-spine relationship during total hip arthroplasty and explored the degenerative presentations and management of four common lumbar disorders. The review showed that patients with the spinal deformity in ankylosing spondylitis (AS) were characterized by thoracolumbar kyphosis with corresponding hip extension and pelvic retroversion, prone to anterior hip dislocation; patients with lumbar spinal fusion (LSF) were more susceptible to prosthetic impingement and ultimate dislocation, especially in the limited posterior tilt of the pelvis while sitting; those with degenerative disc disease (DDD) had a greater compensatory pelvic posterior angle while standing and greater hip joint flexion while sitting to compensate for the reduced lumbar flexion; those with degenerative lumbar spondylolisthesis (DSPL) demonstrated a pelvic flexibility with a much wider range and relative acetabular anteversion, especially when standing. Recommendation: According to the literature, spinal osteotomy and total hip arthroplasty are the most common surgical interventions in AS cases. DSPL is classified into the Flexible &amp; Unbalanced type and should be placed more posteriorly, but the literature suggests that patients with lumbar instability should first be placed in a more predictable position. In contrast, LSF and DDD are categorized as the Rigid &amp; Balanced type. For these two types of disorders, the literature suggests that acetabular prostheses require more anterior tilt at the time of implantation. Conclusion: These findings indicate that for degenerative lumbar disorders, a balance between stable component implantation and minimal wear should be based on the different changes in spinopelvic mobility.

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

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

Total, hemi, or dual-mobility arthroplasty for the treatment of femoral neck fractures in patients with neurological disease : analysis of 9,638 patients from the Swedish Hip Arthroplasty Register.

The aim of this study was to investigate the potentially increased risk of dislocation in patients with neurological disease who sustain a femoral neck fracture, as it is unclear whether they should undergo total hip arthroplasty (THA) or hemiarthroplasty (HA). A secondary aim was to investgate whether dual-mobility components confer a reduced risk of dislocation in these patients. We undertook a longitudinal cohort study linking the Swedish Hip Arthroplasty Register with the National Patient Register, including patients with a neurological disease presenting with a femoral neck fracture and treated with HA, a conventional THA (cTHA) with femoral head size of ≤ 32 mm, or a dual-mobility component THA (DMC-THA) between 2005 and 2014. The dislocation rate at one- and three-year revision, reoperation, and mortality rates were recorded. Cox multivariate regression models were fitted to calculate adjusted hazard ratios (HRs). A total of 9,638 patients with a neurological disease who also underwent unilateral arthroplasty for a femoral neck fracture were included in the study. The one-year dislocation rate was 3.7% after HA, 8.8% after cTHA < 32 mm), 5.9% after cTHA (= 32 mm), and 2.7% after DMC-THA. A higher risk of dislocation was associated with cTHA (< 32 mm) compared with HA (HR 1.90 (95% confidence interval (CI) 1.26 to 2.86); p = 0.002). There was no difference in the risk of dislocation with DMC-THA (HR 0.68 (95% CI 0.26 to 1.84); p = 0.451) or cTHA (= 32 mm) (HR 1.54 (95% CI 0.94 to 2.51); p = 0.083). There were no differences in the rate of reoperation and revision-free survival between the different types of prosthesis and sizes of femoral head. Patients with a neurological disease who sustain a femoral neck fracture have similar rates of dislocation after undergoing HA or DMC-THA. Most patients with a neurological disease are not eligible for THA and should thus undergo HA, whereas those eligible for THA could benefit from a DMC-THA. Cite this article: Bone Joint J2022;104-B(1):134-141.