No Difference in Dislocation Rates Comparing Large Diameter Jumbo Femoral Heads and Dual-Mobility Bearings in Revision Total Hip Arthroplasty

Surveillance of Dual-Mobility Hip Systems: Damage Mode and Clinical Data Analysis

BACKGROUND

Hip instability following total hip arthroplasty (THA) is among the most common indications for revision surgery. The implantation of dual-mobility (DM) systems, designed to improve stability, continues to rise, and thus, characterizing in vivo implant damage modes is paramount.

METHODS

Under an implant retrieval protocol, 51 DM THA systems were analyzed. Each component was examined for macroscopic damage and microscopically graded for fretting corrosion at the trunnion interface. Clinically relevant data were collected from medical records.

RESULTS

Revision indications included mechanical complications (n = 15, 27%), infection (n = 12, 22%), and dislocation (n = 9, 16%). The average duration of implantation was 12 months, which significantly correlated with summed femoral head taper corrosion (P = 0.044). Average summed fretting and corrosion scores were 2.9 and 3.0 for heads (two regions, 2 to 8 summed scores possible) and 7.6 and 7.1 for trunnions (four quadrants, 4 to 16 summed scores possible), respectively. Scratching (n = 26, 65.4%) was the most common damage mode on articular surfaces of acetabular cups, burnishing (n = 29, 55.2%) on metal liners, and edge deformation (n = 22, 45.5%) on polyethylene liners. Screw-liner corrosion was noted on 10.3% (n = 3) of available acetabular liners; an increased incidence of acetabular and femoral osteolysis was noted when this damage mode was present (P = 0.019 and P = 0.022, respectively).

CONCLUSIONS

This series demonstrated in vivo damage of DM THA components following short-term-to-midterm (zero to five years) implantation, with overall mild-to-moderate fretting and corrosion scores. Femoral head taper corrosion correlated with longer implantation, and amplified trunnion corrosion was observed in the setting of infection. Screw-liner corrosion may be related to acetabular and femoral osteolysis. This study indicates trends that merit further evaluation.

The Association of Jumbo Femoral Heads and Acetabular Cup Position on Patient Outcomes After Modern Posterior Approach Total Hip Arthroplasty

BACKGROUND

Use of jumbo femoral heads (≥ 40 mm) in total hip arthroplasty decreases postoperative dislocation; however, may leave patients more susceptible to groin pain. Limited data exist for the effect of jumbo femoral heads and acetabular cup position on modern patient-reported outcome measures (PROMs). This study evaluated the effect of jumbo femoral heads and acetabular cup position on PROMs after primary total hip arthroplasty.

METHODS

A total of 328 consecutive primary THAs of a single implant system with various femoral head sizes (36% ≥ 40 mm) were retrospectively reviewed. Acetabular cup inclination and anteversion were radiographically measured. Demographics, comorbidities, and implant sizes were documented. Prospectively collected University of California Los Angeles Activity Level, Hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS JR), and satisfaction were evaluated. The mean follow-up was 1.2 years (range, one to five). A P-value of 0.05 was considered statistically significant.

RESULTS

Femoral head size was not associated with University of California Los AngelesActivity Level scores at any time point (P ≥ 0.209). Independent of patient sex, the mean HOOS JR score was significantly higher in the ≥ 40 mm femoral head group compared to the < 40 mm head group at 4 months although not reaching a clinically significant threshold (mean difference 4.4, 95% CI [confidence interval]: 0.5 to 8.3, P = 0.027); however, mean scores at the latest follow-up were not different (P = 0.956). The HOOS JR scores ≥ 90 and being "very satisfied or satisfied" were associated with a wide range and several combinations of acetabular cup inclination and anteversion. A total of 88.9% of patients reported being "very satisfied or satisfied" at the latest follow-up.

CONCLUSIONS

Patients achieved comparable PROMs regardless of femoral head size, suggesting large femoral heads may not leave patients susceptible to groin pain in addition to reducing the risk of postoperative dislocation. Excellent patient outcomes correlated with wide ranges of acetabular cup positions.

LEVEL OF EVIDENCE

III.

Modular dual-mobility constructs outperformed large femoral heads in 299 revision total hip arthroplasties at mid-term follow-up

Aims

The purpose of this study was to directly compare the Modular Dual Mobility (MDM) Mobile Bearing Hip System (Stryker, USA) and large femoral heads (LFHs) in revision total hip arthroplasties (THAs) at mid-term follow-up, with specific emphasis on survival free of re-revision for dislocation, any re-revision, dislocation, and the risk of metal-related complications.

Methods

We identified 299 revision THAs performed at a single tertiary care academic institution from March 2011 to July 2014. Aseptic loosening of the acetabular component (n = 65), dislocation (n = 58), and reimplantation as part of a two-stage exchange protocol (n = 57) were the most common reasons for index revision. MDM constructs were used in 123 cases, and LFHs were used in 176 cases. Mean age was 66 years (28 to 93), mean BMI was 31 kg/m2 (18 to 55), and 45% (n = 136) were female. Mean follow-up was seven years (2 to 12).

Results

The ten-year survival free of re-revision for dislocation was 99% (95% CI 95 to 100) in the MDM cohort and 91% (95% CI 84 to 96) in the LFH cohort, with a significantly increased risk of re-revision for dislocation in the LFH cohort (HR 7.1 (95% CI 1.3 to 40.8); p = 0.023). The ten-year survival free of any re-revision was 92% (95% CI 82 to 99%) in the MDM cohort and 84% (95% CI 74 to 90) in the LFH cohort with a significantly increased risk of any re-revision in the LFH cohort (HR 2.6 (95% CI 1.1 to 5.9); p = 0.024). The ten-year survival free of any dislocation was 95% (95% CI 85 to 99) in the MDM cohort and 87% (95% CI 78 to 92) in the LFH cohort with a significantly increased risk of any dislocation in the LFH cohort (HR 2.7 (95% CI 1.1 to 6.3); p = 0.028). There were no re-revisions or reoperations for metallosis or corrosion in the MDM cohort.

Conclusion

In this head-to-head comparison, revision THAs with a MDM construct safely and effectively lowered the risk of re-revision for dislocation, any re-revision, and any dislocation compared to LFH at mid-term follow-up. There were no re-revisions or reoperations for metallosis or corrosion in the MDM cohort.

Dual-Mobility Articulations in Revision Total Hip Arthroplasty: A Comparison with Metal or Ceramic on Highly Cross-Linked Polyethylene and Constrained Articulations

BACKGROUND

The increased availability of dual-mobility acetabular constructs (DMCs) provides surgeons with a newer option to increase the effective femoral head size in revision total hip arthroplasty (rTHA). We sought to evaluate risks of re-revision and prosthetic dislocation following rTHA involving a DMC compared with other articulations.

METHODS

A cohort study was conducted using data from a U.S. integrated health-care system's Total Joint Replacement Registry. Adult patients who underwent primary THA and went on to undergo an aseptic rTHA in 2002 to 2022 were identified. Patients who received a DMC, a constrained liner, or a metal or ceramic unipolar femoral head on highly cross-linked polyethylene (XLPE) at the time of rTHA were the treatment groups. Subsequent aseptic re-revision and dislocation were the outcomes of interest. Multivariable Cox proportional-hazards regression was used to evaluate the risks of the outcomes, with adjustment for patient, operative, and surgeon confounders.

RESULTS

The analyzed rTHAs comprised 375 with a DMC, 268 with a constrained liner, 995 with a <36-mm head on XLPE, and 2,087 with a ≥36-mm head on XLPE. DMC utilization increased from 1.0% of rTHAs in 2011 to 21.6% in 2022. In adjusted analyses, a higher re-revision risk was observed for the constrained liner (hazard ratio [HR] = 2.43, 95% confidence interval [CI] = 1.29 to 4.59), <36 mm on XLPE (HR = 2.05, 95% CI = 1.13 to 3.75), and ≥36 mm on XLPE (HR = 2.03, 95% CI = 1.19 to 3.48) groups compared with the DMC group. A higher dislocation risk was observed in both XLPE groups (<36 mm: HR = 2.04, 95% CI = 1.33 to 3.14; ≥36 mm: HR = 2.46, 95% CI = 1.69 to 3.57) compared with the DMC group; a nonsignificant trend toward a higher dislocation rate in the group with a constrained liner than in the DMC group was also observed.

CONCLUSIONS

In a large U.S.-based cohort, rTHAs using DMCs had the lowest re-revision risk and dislocation risk. Both outcomes were significantly lower than those using a unipolar femoral head on XLPE, re-revision risk was significantly lower than using a constrained liner, and dislocation risk trended toward a lower risk than using a constrained liner.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Decreased Instability in High-Risk (Hip-Spine 2B) Patients After Modifications of Surgical Planning and Technique

BACKGROUND

Patients undergoing primary total hip arthroplasty (THA) who have spinal deformity and a stiff spine are the highest-risk group for instability. Despite the increasing use of dual-mobility cups and large femoral heads, dislocation remains a major complication after THA. Preoperative planning becomes a critical aspect of ensuring precise component positioning within a safe zone. The purpose of this study was to investigate dislocation rates over a 9-year period.

METHODS

A retrospective review of 4,731 THAs performed by 3 orthopaedic surgeons between January 2014 and March 2023 was performed. Spinopelvic measurements were conducted to determine the hip-spine classification group for each patient. Only patients classified as 2B (pelvic incidence-lumbar lordosis > 10° and Δsacral slope < 10°) were eligible. Both absolute and relative dislocation frequencies were then analyzed using time-series analysis techniques and Fisher's exact tests.

RESULTS

A total of 281 hip-spine 2B patients undergoing primary THA were eligible for analysis (57% women; mean age, range: 66 years, 23 to 87; mean body mass index, range: 28, 16 to 45). The overall dislocation rate was 4.3%. Use of femoral head sizes ≥ 40 mm increased from 4% in 2014 to 2019 to 37% in 2020 to 2023 (P < .001), while the use of dual-mobility cups decreased from 100% in 2014 to 2019 to 37% in 2020 to 2023 (P < .001). Acetabular component planning was changed from the supine plane to the standing plane in February 2020. Those changes in surgical practice were notably correlated with a significant decrease in dislocation rates from 6.8% in 2014 to 2019 to 1.5% in 2020 to 2023 (P = .03).

CONCLUSIONS

Our study demonstrates that the introduction of advanced preoperative THA planning to the standing plane, coupled with precise intraoperative technology for implant placement, can significantly reduce the risk of instability in high-risk THA patients. Notably, we observed a significant decrease in dislocation rates, which aligned with the shift in surgical practice.

LEVEL OF EVIDENCE

IV.

Dual-mobility bearings reduce instability but may not be the only answer in revision total hip arthroplasty for recurrent dislocation

Aims

There is little information in the literature about the use of dual-mobility (DM) bearings in preventing re-dislocation in revision total hip arthroplasty (THA). The aim of this study was to compare the use of DM bearings, standard bearings, and constrained liners in revision THA for recurrent dislocation, and to identify risk factors for re-dislocation.

Methods

We reviewed 86 consecutive revision THAs performed for dislocation between August 2012 and July 2019. A total of 38 revisions (44.2%) involved a DM bearing, while 39 (45.3%) and nine (10.5%) involved a standard bearing and a constrained liner, respectively. Rates of re-dislocation, re-revision for dislocation, and overall re-revision were compared. Radiographs were assessed for the positioning of the acetabular component, the restoration of the centre of rotation, leg length, and offset. Risk factors for re-dislocation were determined by Cox regression analysis. The modified Harris Hip Scores (mHHSs) were recorded. The mean age of the patients at the time of revision was 70 years (43 to 88); 54 were female (62.8%). The mean follow-up was 5.0 years (2.0 to 8.75).

Results

DM bearings were used significantly more frequently in elderly patients (p = 0.003) and in hips with abductor deficiency (p < 0.001). The re-dislocation rate was 13.2% for DM bearings compared with 17.9% for standard bearings, and 22.2% for constrained liners (p = 0.432). Re-revision-free survival for DM bearings was 84% (95% confidence interval (CI) 0.77 to 0.91) compared with 74% (95% CI 0.67 to 0.81) for standard articulations, and 67% (95% CI 0.51 to 0.82) for constrained liners (p = 0.361). Younger age (hazard ratio (HR) 0.92 (95% CI 0.85 to 0.99); p = 0.031), lower comorbidity (HR 0.44 (95% CI 0.20 to 0.95); p = 0.037), smaller heads (HR 0.80 (95% CI 0.64 to 0.99); p = 0.046), and retention of the acetabular component (HR 8.26 (95% CI 1.37 to 49.96); p = 0.022) were significantly associated with re-dislocation. All DM bearings which re-dislocated were in patients with abductor muscle deficiency (HR 48.34 (95% CI 0.03 to 7,737.98); p = 0.303). The radiological analysis did not reveal a significant relationship between restoration of the geometry of the hip and re-dislocation. The mean mHHSs significantly improved from 43 points (0 to 88) to 67 points (20 to 91; p < 0.001) at the final follow-up, with no differences between the types of bearing.

Conclusion

We found that the use of DM bearings reduced the rates of re-dislocation and re-revision in revision THA for recurrent dislocation, but did not guarantee stability. Abductor deficiency is an important predictor of persistent instability.

Large Femoral Heads and Select Dual-Mobility Bearings Are Associated With Reduced Instability in Contemporary Posterior Approach Total Hip Arthroplasty

BACKGROUND

Postoperative dislocation is considered the main drawback of posterior approach total hip arthroplasty (THA). Thinner highly cross-linked polyethylene and dual-mobility bearings allow maximizing femoral head diameter per a given cup size. This study evaluated dislocation rates as large femoral head bearings were introduced into a practice over an 11-year period.

METHODS

A total of 1,511 consecutive primary THAs were retrospectively reviewed. Demographics, implant sizes, femoral head-acetabular cup ratio, and dislocation status were collected from the electronic medical record. Data were evaluated using time series analysis techniques as larger femoral heads, thinner polyethylene liners, and dual-mobility bearings were introduced. The cohort was 57% women with mean age and body mass index of 62 years (range, 13 to 93) and 31 kg/m² (range, 13 to 54), respectively.

RESULTS

The overall dislocation rate was 0.98%. Use of femoral head sizes ≥ 40 millimeters increased from 4% in the years 2010 to 2016 to 51% in the years 2017 to 2021, correlating with a 50% reduction in dislocation rate from 1.4% to 0.7% (P = .279). Also, no dislocations occurred in patients who had dual-mobility bearings or ≥ 40-millimeter femoral heads (P = .007). Twelve of 14 dislocations occurred in cases with head-cup ratio < 0.7 (P = .013). Thirteen of 14 dislocations were in women (P = .005).

CONCLUSION

Maximizing the femoral head diameter per given cup size correlated with a decrease in dislocation rate in modern posterior approach THA. Furthermore, these results suggest that dual-mobility articulations should be reserved for high-risk patients or patients in whom a 40-millimeter femoral head is not possible.

LEVEL OF EVIDENCE

IV-consecutive case series; no control group.

The Role of Dual-Mobility Components in Total Hip Arthroplasty

➤

Dual mobility (DM) refers to a now widely available option for total hip articulation. DM implants feature a small inner head, a hard bearing, that connects via a taper fit onto the femoral trunnion. This head freely rotates but is encased inside a larger, outer polyethylene head that articulates with a smooth acetabular component.

➤

DM acetabular components are available in the form of a monoblock shell or as a liner that is impacted into a modular shell, providing a metal articulation for the polyethylene outer head.

➤

DM is designed to increase hip stability by providing the arthroplasty construct with a higher jump distance, head-to-neck ratio, and range of motion prior to impingement.

➤

The use of DM in total hip arthroplasty continues to increase in the United States for both primary and revision arthroplasty. Surgeons should be aware of the potential benefits and pitfalls.

➤

Long-term data are lacking, especially for modular DM implants. Points of concern include a potential for accelerated polyethylene wear, intraprosthetic dislocation, and modular backside fretting corrosion.

Unstable Total Hip Arthroplasty: Should It Be Revised Using Dual Mobility Implants? A Retrospective Analysis from the R.I.P.O. Registry

Total hip arthroplasty (THA) is one of the most common surgical procedures in orthopedics; however, it is subjected to different kinds of failures, one of them being dislocation. Many different prosthetic designs have been developed to overcome this problem, such as dual mobility coupling. The main purpose of this article is to determine whether there are differences regarding the revision surgery of unstable THA comparing the risk of failure between dual mobility cup (DMC) implants, standard implants, and among different head sizes. A registry-based population study has been conducted by analyzing data collected by the Emilia Romagna Registry of Orthopedic Prosthetic Implants (RIPO), including a total of 253 implants failed for dislocation and instability that were operated on by cup revision surgery between 2000 and 2019. The selected population has been divided into two groups based on the insert type: standard and DMC. The age at revision surgery was significantly lower in the standard cup group with respect to DMC (p = 0.014 t-test), with an average age of 71.2 years (33-96 years range) for the standard cups and 74.8 years (48-92 years range) for the DMC group. The cumulative survival of DMC implants was 82.0% at 5-years, decreasing to 77.5% at a 10-year follow-up, which is not significantly different from standard cups (p = 0.676, Log-Rank test). DMC implants showed a significantly lower risk of re-revision for dislocation compared to standard cups (p = 0.049). Femoral heads ≥36 mm had a higher overall survival compared to smaller femoral heads (p = 0.030). This study demonstrated that DMC or femoral heads ≥36 mm are a valid choice to manage THA instability and to reduce the revision rate for dislocation at a mid-term follow-up; in those selected and targeted patients, these options should be taken into consideration because they are associated with better outcomes.