Omnifit acetabular component: a solution to preventing and treating dislocation

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Outcome of the Stryker® Trident 'All-Poly' constraint acetabular insert: a district general hospital experience

INTRODUCTION

Constrained acetabular inserts are designed as revision solutions for unstable total hip arthroplasties to prevent dislocation and as a possible primary option for elderly patients at risk of recurrent dislocation.

PURPOSE

Our aim was to establish clinical and radiological outcomes of an 'all-poly' constrained acetabular device and to highlight reasons for component failure.

METHODS

We retrospectively reviewed our use of the Stryker® Trident 'all-poly' constrained acetabular insert between 2008 and 2013. All inserts were cemented directly into the acetabulum. Demographic data was collated. The indication for use of a constrained insert and postoperative complications were determined. Patients were reviewed clinically and underwent radiographic follow-up.

RESULTS

A total of 56 constrained inserts were utilised during the study period. Follow-up was for a minimum of 2 years (mean 4.0 years and range 2.0-6.8 years). The mean latest follow-up Oxford hip score was 34.6 (11-48). One postoperative superficial wound infection, 1 breakage of the constraining ring without clinical consequence and 1 recognised complication of liner failure at the bipolar interface were noted.

CONCLUSIONS

In the short to medium term, acetabular constraint offers a useful primary or revision option in patients at risk or with recurrent dislocation.

An Insight into Methods and Practices in Hip Arthroplasty in Patients with Rheumatoid Arthritis

Total hip arthroplasty (THA) has improved the quality of life of patients with hip arthritis. Orthopedic community is striving for excellence to improve surgical techniques and postoperative care. Despite these efforts, patients continue facing postoperative complications. In particular, patients with rheumatoid arthritis display a higher risk of certain complications such as dislocation, periprosthetic infection, and shorter prosthesis durability. In this review we present the current knowledge of hip arthroplasty in patients with rheumatoid arthritis with more insight into common practices and interventions directed at enhancing recovery of these patients and current shortfalls.

Short-Term Results of Novel Constrained Total Hip Arthroplasty

Constrained acetabular components have only been recommended as a salvage option for the persistently unstable total hip arthroplasty (THA), due to limited range of motion and less than satisfactory component failure rates. This is a retrospective review of 137 patients with 154 consecutive primary constrained THAs performed between November 2003 and August 2007. We reviewed serial radiographs, postoperative complications, groin/thigh pain, and compared preoperative and postoperative Harris Hip Scores. With a mean follow-up of 6 years, there was 1.9% dislocation rate, 0% component failure rate, and 2.6% infection rate. Seven patients reported continued groin pain, and three had continued thigh pain. One patient showed radiographic evidence of 1 mm polyethylene wear. Radiographic review showed no evidence of osteolysis or stem subsidence. Harris Hip Scores improved from a mean of 68.8 (range 58-87) preoperatively to 98.9 (range 65-100) at final clinical assessment. This constrained acetabular prosthesis had a dislocation rate of less than 2%, with 0% component failure rate at a minimum of 2 years of follow-up suggesting this prosthesis may be a viable alternative for patients at risk for instability or those known to have recurrent instability.

The medium term outcome of the Omnifit constrained acetabular cup

Recurrent dislocation requiring revision surgery occurs in approximately 4% of primary total hip arthroplasties (THAs). To reduce this risk, or to treat those patients who recurrently dislocate, a constrained acetabular component may be used, however there are concerns over the success of such components due to increased mechanical stresses. The purpose of this study was to analyse the survivorship and radiological results for the Omnifit constrained acetabular component, providing a longer patient reported outcome follow-up than previous studies. 117 patients (median age 82 years) underwent a THA with an Omnifit constrained acetabular component. Of these, 45 were primary replacements and 72 were revisions. Survivorship analysis was performed and patients were assessed both radiologically and functionally. At follow-up, 53 patients (45.3%) had died at a median time of 33 months from operation. The median overall follow-up was 7.0 (5.5-8.2) years. Survivors (median age 83 years) reported a median Oxford Hip Score (OHS) of 16.6 (0-48), 87.8% were satisfied with their surgery. 45 (91.8%) of the acetabular components were stable radiologically, 48 (96%) of the femoral components were stable (5 uncemented, 43 cemented) and two possibly unstable. Four of the 117 patients underwent further surgery. Only one required revision of the prosthesis and this was for a periprosthetic fracture. In the medium term the Omnifit constrained acetabular component prevents dislocation and does not cause excessive loosening of either the acetabular or femoral components in our patient population. Our results support the use of the Omnifit constrained acetabular component in elderly patients at risk of dislocation with low functional demand.

Trilogy-constrained acetabular component for recurrent dislocation

32 patients received a Trilogy- or Trilogy-Longevity-constrained acetabular liner for recurrent dislocations after total hip replacement. The constrained liner was inserted into a well-fixed Trilogy acetabular shell with snap fit. At 1.8-year followup (range 3-63 months), 4 patients had suffered further dislocation(s) (12%), and one patient had revision surgery for a loosened acetabular shell. Radiologic evaluation detected no definitively loose components, but one patient with progressing radiolucent lines around the femoral component and one patient with an acetabular cyst were found, as well as a patient with a loose locking ring (but otherwise no failure). The nineteen patients who were available for the present followup had a mean Harris Hip Score of 81. The constrained liner is an effective method of dealing with recurrent dislocations in well-fixed components.

Management of hip instability with a cemented, constrained acetabular component

We evaluated the use of a cemented constrained acetabular component to treat recurrent or potential instability after hip replacement. Over a seven year period, 109 patients who had undergone 110 operations were identified from hospital records. Patients were reviewed based on clinical and radiological follow-up. Post-operative function and quality of life was assessed using the Oxford Hip Score (OHS) and SF-12. From an original cohort of 109 patients, 9 patients were lost to follow up. Of the remaining 100 patients, the mean follow up was 2.9 years (SD±2 years). There were 4 failures, requiring 3 further revisions. The mean post-operative OHS was 33, SF-12 PCS 34 and SF12 MCS 52. 5-year survivorship was 90%. Cementing a constrained acetabular component provides satisfactory mid term results in patients at high risk of hip dislocation.

Revision for recurrent dislocation of total hip replacement

BACKGROUND AND PURPOSE

Dislocation is one of the commonest complications of total hip arthroplasty with an incidence of between 0.5 and 9.2%. Despite this, little is known of the outcome of treatment strategies for dislocation. The aim of this study was to establish the optimal strategy for the operative management of recurrent dislocation following THA taking account of the surgical approach employed in the replacement that became unstable and the direction of the instability that followed.

METHODS

We reviewed 70 patients who underwent revision surgery for recurrent dislocation after total hip arthroplasty (THA), 38 through the transgluteal (Hardinge) and 32 through the posterior approach.52 of these followed primary and 18 followed revision THA for reasons other than instability.We recorded the surgical approach, the direction of dislocation and the operative strategy employed for each case.

RESULTS

We achieved stability in 75% of patients who dislocated after primary and 50% after revision THA. 77% of dislocations performed initially through the transgluteal approach were anterior and 88% through the posterior approach were posterior. Following the transgluteal approach, we stabilised anterior dislocation in 54% of cases. Following the posterior approach we stabilised posterior dislocation in 79%. The most successful operative strategy overall was cup augmentation which conferred stability in 90% of cases.

INTERPRETATION

Instability after primary total hip replacement is easier to treat (75% chance of success) than after revision total hip replacement (50% chance of success). Although previous studies have shown that the posterior approach has a slightly higher risk of dislocation, this study has shown that achieving stability after a posterior dislocation is more likely than after an anterior dislocation. The outcome of revision for instability depends on the surgical approach used initially, and the direction of dislocation.

Instability after total hip arthroplasty: treatment with large femoral heads vs constrained liners

One of the most common complications after total hip arthroplasty is instability. This study reviewed the recent literature concerning the indications, contraindications, and results of recent studies using both constrained liners and large femoral heads to treat instability after total hip arthroplasty. We also report on the results of a series of 41 patients (52 hips) considered being at high risk for dislocation who were treated with large-diameter metal-on-metal bearings and who were compared with a matched group of hips treated with standard-size metal-on-polyethylene bearings. The large-diameter femoral head group had no dislocations at a minimum follow-up of 24 months, whereas the standard-size group had 2 dislocations. We support the use of large femoral heads to treat instability in a wide variety of patients because of the increased stability, decreased wear of modern metal-on-metal designs, increased range of motion, and variety of revision options.