Acetabular liner with focal constraint to prevent dislocation after THA

Evaluating the risk of return to the operating room across all elective orthopaedic procedures

BACKGROUND

Although elective procedures have life-changing potential, all surgeries come with an inherent risk of reoperation. There is a gap in knowledge investigating the risk of reoperation across orthopaedics. We aimed to identify the elective orthopaedic procedures with the highest rate of unplanned reoperation and the reasons for these procedures having such high reoperation rates.

METHODS

Patients in the NSQIP database were identified using CPT and ICD-10 codes. We isolated 612,815 orthopaedics procedures from 2018 to 2020 and identified the 10 CPT codes with the greatest rate of unplanned return to the operating room. For each index procedure, we identified the ICD-10 codes for the reoperation procedure and categorized them into infection, mechanical failure, fracture, wound disruption, hematoma or seroma, nerve pathology, other, and unspecified.

RESULTS

Below knee amputation (BKA) (CPT 27880) had the highest reoperation rate of 6.92% (37 of 535 patients). Posterior-approach thoracic (5.86%) or cervical (4.14%) arthrodesis and cervical laminectomy (3.85%), revision total hip arthroplasty (5.23%), conversion to total hip arthroplasty (4.33%), and revision shoulder arthroplasty (4.22%) were among the remaining highest reoperation rates. The overall leading causes of reoperation were infection (30.1%), mechanical failure (21.1%), and hematoma or seroma (9.4%) for the 10 procedures with the highest reoperation rates.

CONCLUSIONS

This study successfully identified the elective orthopaedic procedures with the highest 30-day return to OR rates. These include BKA, posterior thoracic and cervical spinal arthrodesis, revision hip arthroplasty, revision total shoulder arthroplasty, and cervical laminectomy. With this data, we can identify areas across orthopaedics in which revising protocols may improve patient outcomes and limit the burden of reoperations on patients and the healthcare system. Future studies should focus on the long-term physical and financial impact that these reoperations may have on patients and hospital systems.

LEVEL OF CLINICAL EVIDENCE

IV.

Removing Cemented Dual Mobility Liners From Acetabular Components: A Technical Tip for a Challenging Surgical Problem

Dislocation remains the leading cause of failure following revision total hip arthroplasty. Dual mobility (DM) constructs, including monoblock cups designed for cementation, reduce but do not eliminate this risk. Cemented DM constructs offer several unique advantages in revision total hip arthroplasty, and as such, they have gained popularity. Despite their advantages, a portion of these implants will require revision for infection or recurrent dislocation. Removal of a cemented DM cup presents numerous challenges, and there is no effective published technique. Here, we present an effective technique for the safe removal of one design of cemented DM cup.

Outcomes of total hip arthroplasty with a standard prosthesis for the affected hip in patients with poliomyelitis sequelae: a mid-term retrospective follow-up study

INTRODUCTION

Total hip arthroplasty for poliomyelitis sequelae could be a technical challenge due to the higher risk for prosthetic dislocation and degenerative changes in the affected limbs. This study aimed to analyse the mid-term outcomes of primary total hip arthroplasty on the affected hip with standard prosthesis.

MATERIALS AND METHODS

From January 2008 to January 2018, 32 patients with poliomyelitis sequelae underwent total hip arthroplasty on the affected hip with standard prosthesis. Clinical and radiographical outcomes, complications, and prosthesis survival rates were evaluated.

RESULTS

After a mean follow-up of 7.9 (4.4-13.1) years, the Harris Hip Score, University of California Los Angeles activity level rating, and 12-item Short Form Health Survey Questionnaire scale score significantly improved. The abduction and flexion motions of the hip joint improved dramatically, and the visual analogue scale pain score decreased significantly. The leg length discrepancy was effectively corrected. During the follow-up, one patient experienced prosthetic dislocation, one underwent revision surgery due to acetabular component loosening, two had osteolysis, four had heterotopic ossification, two experienced transient sciatic nerve palsy, and one had intermuscular vein thrombosis. The prosthesis survival rate was 96.9% at 5 years postoperatively. No periprosthetic infection occurred.

CONCLUSION

Total hip arthroplasty with standard prosthesis could be an effective treatment for hip arthropathy on the affected hip of patients with poliomyelitis sequelae, resulting in good clinical outcomes and few complications. Constrained liner and dual mobility articulation are not recommended unless the hip muscle strength of the abductor is < III.

Survivorship and Clinical Outcomes of Constrained Acetabular Liners in Primary and Revision Total Hip Arthroplasty: A Systematic Review

BACKGROUND

Several studies have evaluated the survivorship and clinical outcomes of constrained acetabular liners (CALs) in complex primary and revision total hip arthroplasty with hip instability; however, there remains no consensus on the overall performance of this constrained implant. We therefore performed a systematic review of the literature to examine survivorship and complication rate of CAL usage.

METHODS

A systematic review of the literature in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. A comprehensive search of PubMed, MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews was conducted for English articles using various combinations of keywords.

RESULTS

In all, 37 articles met the inclusion criteria. A total of 4152 CALs were implanted. The all-cause reoperation-free survivorship was 79.9%. The overall complication rate was 22.2%. Dislocation was the most common complications observed and the most frequent reason for reoperation with an incidence of 9.4% and 9.2%, respectively. Infection after CAL placement had an incidence of 4.6%. The reoperation rate for aseptic acetabular component loosening was 2.9%. Overall, patients had improved outcomes as documented by postoperative hip scores.

CONCLUSION

CALs usage have a relatively high complication rate, particularly when compared with current bearing alternatives (dual mobility cups and large diameter femoral heads), however, it remains a valuable salvage procedure in complex patients affected by recurrent dislocation and implant instability. Newer designs have shown reduced impingement and higher survivorship free from dislocation. However, CALs should only be used when the reasons of instability have been correctly recognized and optimized.

Dual mobility acetabular construct with freedom constrained liner for treatment of recurrent dislocations after total hip arthroplasty: A case report and literature review

•

Dual-mobility bearings improve stability in total hip arthroplasty (THA) but may fail to prevent postoperative dislocation.

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Dry revision with a compatible constrained liner system can provide an effective salvage option for instability after THA.

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The unique G7 constrained liner system offers good short-term stability and range of motion.

Introduction

Recurrent dislocation after total hip arthroplasty (THA) using the dual mobility cup system can present challenges, while dual-mobility THA bearings can improve stability in both primary and revision total hip arthroplasties.

Presentation of case

A 72-year-old woman with a history of schizophrenia underwent a left primary THA using the G7 dual mobility system. Two postoperative posterior dislocations occurred within 2 months post-surgery. The patient underwent revision surgery in which the metal liner and dual mobility head were exchanged using the Freedom constrained liner system without revision of the cup and stem. As of this writing, 28 months after the revision surgery, no further dislocations have occurred. The implants are stable, and the patient has good range of motion.

Discussion

Dual-mobility bearings are utilized to improve stability in both primary and revision total hip arthroplasties, but even if the dual mobility system is chosen, it sometimes fails to prevent postoperative dislocation. Although a relatively high failure rate has been reported in THA using the constrained liner system, this patient’s clinical course suggests that the G7 Freedom constrained liner system can be an efficacious option for some patients with unstable hip joints who undergo THA using the dual mobility system.

Conclusion

A modern constrained liner system such as the G7 Freedom liner may provide an improved salvage solution for joint instability in dual mobility THA.

Comparison of Constrained Acetabular Components and Dual Mobility Cups in Revision Total Hip Arthroplasty: A Literature Review

Recurrent instability remains a common cause of failure after revision total hip arthroplasty (THA). Dual mobility (DM) cups and designs with constrained acetabular liners (CAL) have both been developed to help overcome this challenge. The aim of this report is to compare safety and efficacy outcomes of both designs based on the literature. A comprehensive literature review including published evidence on the results of DM and CAL in revision THA was performed and summarized. Available literature focusing on overall survival, dislocation, loosening, intra-prosthetic dislocation (IPD), and functional outcomes were analysed. Forty-six reports including an evaluation of 5,617 total hips were evaluated were included in the review. The included studies were divided into two distinct groups based on implantation approach: i) CAL (n=15) and ii) DM (n=31). The DM group had higher overall survival rates (94.7% vs. 81.0%), lower dislocation rates (2.6% vs. 11.0%), and lower acetabular loosening rates (1.0% vs. 2.0%) compared to the CAL group. IPDs were reported in 6 studies (mean rate, 0.6%). No differences in functional outcomes were identified due to incomplete reports. Our observations reveal that designs with CAL have poorer outcomes as compared to DM cups in revision THA. Currently, the use of DM seems more appropriate since they offer lower rates of dislocations, loosening and re-revisions in the short- and mid-term. Concerns regarding the potential of increased wear in a younger, high-demand population require additional data and evaluation by long-term studies for the DM design.

Mid-Term Survivorship of a Novel Constrained Acetabular Device

BACKGROUND

Recurrent instability after total hip arthroplasty is a difficult complication. In certain cases, a constrained acetabular device is needed to address these issues. The purpose of this study is to report the midterm outcomes and survivorship of a single novel constrained liner device.

METHODS

A retrospective review as performed on all procedures (except first stage exchange for infection) in which a Freedom Constrained (Zimmer Biomet, Warsaw, IN) liner was used between December 2003 and November 2016. Patients with 2-year minimum follow-up or failure were included, yielding a cohort of 177 patients. Procedures were 130 aseptic revisions, 40 reimplantations following infection eradication, and 7 complex primaries. The constrained mechanism was implanted in 46 hips (26%) to treat active instability and 131 hips (74%) for increased risk of instability and intraoperative instability. Patients had on average 3.4 previous surgeries.

RESULTS

With an average 7.1-year follow-up, 11 hips dislocated (6.2%), and 13 hips (7.3%) were revised for acetabular aseptic loosening, resulting in an overall constrained aseptic or mechanical failure rate of 13.6%. Nineteen hips (10.7%) failed from infection with 58% of these having had a previous infection. Patients with active instability had significantly higher failure for dislocation than patients who were at risk (15.2% vs 3%, P = .01). All-cause survival rate at 7 years was 74.8%, aseptic survival was 83.6%, and survival for instability was 91.8%.

CONCLUSION

Revision for instability remains challenging as many patients have had numerous previous surgeries and at-risk anatomy. Constrained inserts are one option to manage instability, but a high rate of recurrence can still occur.

Multivariate analysis of risk factors for re-dislocation after revision for dislocation after total hip arthroplasty

BACKGROUND

The treatment for recurrent dislocation of a total hip arthroplasty is surgical using varied techniques and technologies to reduce the chances of re-dislocation and re-revision. The goal of this study is to compare operative techniques to reduce re-dislocation and re-revision in revision hip arthroplasty due to recurrent dislocations.

METHODS

A retrospective study of revision hip arthroplasties done due to recurrent dislocation prior to 01 January 2014. Electronic physician and provincial health records were used to collect patients' initial and follow-up data. Treatment failure was defined as either aseptic re-revision or re-dislocation without revision. Time to event was considered as the re-revision date or the date of second dislocation when the latter endpoint was used.

RESULTS

Of 379 operations, 88 (23.2%) had aseptic repeat revision or recurrent dislocation. Of these: 66 (75.0%) due to dislocation with re-revision; 10 (11.4%) due to dislocation with no re-revision surgery; 5 (5.7%) due to aseptic loosening of components; 3 (3.4%) due to osteolysis; 3 (3.4%) due to pseudotumour; and 1 (1.1%) due to periprosthetic fracture. The following factors increase risk of failure: the use of augmented-liners (lipped, oblique and high-offset liners; HR = 1.68, 95% CI, 1.05-2.69), periprosthetic femur fracture (HR = 2.80, 95% CI, 1.39-8.21) and pelvic discontinuity (HR = 3.69, 95% CI, 1.66-8.21). Femur head sizes 36-40 mm are protective (HR = 0.54, 95% CI, 0.31-0.86). In abductor dysfunction the use of focal constrained liners decreases the risk of failure (HR = 0.13, 95% CI, 0.018-0.973).

CONCLUSIONS

Larger head sizes and focal constrained liners (abductors dysfunction) should be used and fully constrained liners and augmented-liners should be avoided in a revision hip arthroplasty due to recurrent dislocations.

Lever-Out Resistance of Constrained Hip Liners is Sensitive to Changes in Opening Radius and Liner Design

The constrained liner is an important tool for the treatment of recurrent dislocation, which continues to represent an important challenge in total hip arthroplasty. In constrained liner design, there is a tradeoff between dislocation resistance and range of motion. However, studies investigating their sensitivity to design parameters are scant. Given the relatively high rate of failure of constrained devices, this information is critical to improving their design. This study aimed to use finite element analysis to explore the sensitivity of constrained liner-dislocation resistance to variations in liner opening radius, for two different constraining design features found in contemporary devices. Results showed that a smaller opening radius leads to increased lever-out moment. It was also observed that in liners with localized constraint, lever-out resistance is more sensitive to changes in opening radius than those with circumferential constraint. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1590-1595, 2019.

Increased conditional risk of recurring complications with contralateral total hip arthroplasty surgery

Aims

Increasingly, patients with bilateral hip arthritis wish to undergo staged total hip arthroplasty (THA). With the rise in demand for arthroplasty, perioperative risk assessment and counselling is crucial for shared decision making. However, it is unknown if complications that occur after a unilateral hip arthroplasty predict complications following surgery of the contralateral hip.

Patients and Methods

We used nationwide linked discharge data from the Healthcare Cost and Utilization Project between 2005 and 2014 to analyze the incidence and recurrence of complications following the first- and second-stage operations in staged bilateral total hip arthroplasty (BTHAs). Complications included perioperative medical adverse events within 30 to 60 days, and infection and mechanical complications within one year. Conditional probabilities and odds ratios (ORs) were calculated to determine whether experiencing a complication after the first stage of surgery increased the risk of developing the same complication after the second stage.

Results

A total of 13 829 patients (5790 men and 8039 women) who underwent staged BTHAs were analyzed. The mean age at first operation was 62.9 years (14 to 95). For eight of the 12 outcomes evaluated, patients who experienced the outcome following the first arthroplasty had a significantly increased probability and odds of developing that same complication following the second arthroplasty, compared with those who did not experience the complication after the first surgery. This was true for digestive complications (OR 25.67, 95% confidence interval (CI) 13.86 to 46.08; p < 0.001), urinary complications (OR 6.48, 95% CI 1.7 to 20.73; p = 0.01), haematoma (OR 12.17, 95% CI 4.55 to 31.14; p < 0.001), deep vein thrombosis (OR 4.82, 95% CI 2.34 to 9.65; p < 0.001), pulmonary embolism (OR 12.03, 95% CI 2.02 to 46.77; p = 0.01), deep hip infection (OR 534.21, 95% CI 314.96 to 909.25; p < 0.001), superficial hip infection (OR 1574.99, 95% CI 269.83 to 9291.81; p < 0.001), and mechanical malfunction (OR 117.49, 95% CI 91.55 to 150.34; p < 0.001).

Conclusion

The occurrence of certain complications after unilateral THA is associated with an increased risk of the same complication occurring after staged arthroplasty of the contralateral hip. Patients who experience these complications after unilateral hip arthroplasty should be appropriately counselled regarding their risk profile prior to undergoing staged contralateral hip arthroplasty. Cite this article: Bone Joint J 2019;101-B(6 Supple B):77–83.

An Early Report of the Use of a Modular Dual Mobility Articulation in Revision Acetabular Reconstruction

BACKGROUND

Instability remains one of the main problems after revision hip surgery. The aim of this study was to review the clinical, radiological, and patient-reported outcomes with the use of modular dual-mobility articulation for revision acetabular reconstruction and investigate the risk of fretting corrosion by measuring serum trace metal ion levels.

METHODS

Sixty consecutive patients with a minimum of 24-month follow-up after the insertion of a modular dual-mobility (Stryker, Mahwah, NJ) cup at the time of revision hip surgery were identified. Follow-up included clinical and radiological patient review and functional outcome measures, and a subset of patients had their metal ion (cobalt and chromium) levels checked.

RESULTS

At the most recent follow-up, 5 patients had died, 3 patients have been revised because of ongoing instability, and 3 patients have had revision surgery due to infection. Overall functional outcome (mean Western Ontario and McMaster Universities Osteoarthritis Indexfunction 76, University of California, Los Angeles 5.6, mean Oxford 74.7, Short Form-12 physical 41.6/mental 53.3) and overall pain relief (mean Western Ontario and McMaster Universities Osteoarthritis Index pain score 78.3) scores were good. The mean satisfaction score was 78 of 100. The median serum trace metal chromium and cobalt levels at the most recent follow-up were 0.4 µg/L (range 0.1-6.1 µg/L) and 0.42 µg/L (range 0.21-9.42 µg/L), respectively. The survival with revision as the end point was 90%.

CONCLUSIONS

Dual-mobility cups with modularity represent an excellent option for the patient having revision hip surgery at high risk of instability. This series presents good patient-reported outcome measures and a low complication and revision rate.

Comprehensive Review of Current Constraining Devices in Total Hip Arthroplasty

Hip instability after total joint arthroplasty is a devastating complication. Appropriate management of instability is a challenge. Three components that are commonly used in these challenging scenarios are constrained liners, constrained tripolar components, and nonconstrained tripolar components. The biomaterials and biomechanics of these devices vary. Surgeons must take into account the risks associated with each of these components and some surgical pearls for their use. A thorough review of the recent literature allows comparison of results addressing the short-, medium-, and long-term survival of each component. Constraining devices are a good option when used in salvage procedures in elderly and/or low-demand patients with hip instability. However, constraining devices should not be used to correct deficiencies in surgical technique or implant placement.

Cementation of a Dual Mobility Construct in Recurrently Dislocating and High Risk Patients Undergoing Revision Total Arthroplasty

BACKGROUND

Recurrent instability remains a challenge after revision total hip arthroplasty (THA). We report the outcomes of cementing a cementless dual mobility (DM) component into a stable acetabular shell for the treatment and/or prevention of instability in revision THA.

METHODS

Eighteen patients (18 THAs) undergoing revision THA with a specific monoblock DM construct cemented into a new acetabular component or an existing well-fixed component from 2011 to 2014 were retrospectively reviewed. Tumor prostheses and total femoral replacements were excluded. In 9 patients (50%), components were implanted specifically for recurrent dislocations. Mean age was 64 years; mean follow-up was 3 years. Patients underwent an average of 4 prior hip operations (range 2-6).

RESULTS

No cemented DM cups dissociated at the cement-cup interface. Three patients (17%) experienced a postoperative dislocation. One required a revision to constrained liner and 2 underwent open reduction with retention of the DM construct. Harris Hip Scores improved from 53 to 82 postoperatively (P < .001).

CONCLUSION

Cementation of a monoblock cup DM construct, an off-label use as the construct is not specifically made for cementation, into a well-fixed acetabular component provides an alternative to enhance prosthetic stability in (1) recurrently dislocating THAs with well fixed, well-positioned acetabular components and (2) complex acetabular reconstructions in which constraint should be avoided. While not a perfect solution in this series, DM constructs provide a number of advantages including no added constraint at the interface and a large effective femoral head to diminish prosthetic impingement.

Prevention of Dislocation After Total Hip Arthroplasty

BACKGROUND

Prevention of dislocation after primary total hip arthroplasty (THA) begins with patient preoperative assessment and planning.

METHODS

We performed a literature search to assess historical perspectives and current strategies to prevent dislocation after primary THA. The search yielded 3458 articles, and 154 articles are presented.

RESULTS

Extremes of age, body mass index >30 kg/m², lumbosacral pathology, surgeon experience, and femoral head size influence dislocation rates after THA. There is mixed evidence regarding the effect of neuromuscular disease, sequelae of pediatric hip conditions, and surgical approach on THA instability. Sex, simultaneous bilateral THA, and restrictive postoperative precautions do not influence the dislocation rates of THA. Navigation, robotics, lipped liners, and dual-mobility acetabular components may improve dislocation rates.

CONCLUSIONS

Risks for dislocation should be identified, and measures should be taken to mitigate the risk. Reliance on safe zones of acetabular component positioning is historical. We are in an era of bespoke THA surgery.

Can Dislocation of a Constrained Liner Be Salvaged With Dual-mobility Constructs in Revision THA?

BACKGROUND

Revision THA to treat recurrent instability can itself be complicated by recurrent instability, and when this occurs, this problem is difficult to treat. Some patients' THAs will continue to dislocate despite use of a constrained liner. One option in this difficult-to-treat group is conversion to a dual-mobility (DM) construct, but there are few data on this approach.

QUESTIONS/PURPOSES

(1) What were the Harris hip scores in a small group of patients whose constrained liners were converted to DM constructs to treat recurrent dislocation? (2) What were the redislocation, rerevision, and DM construct retention rates in these patients?

METHODS

We conducted a retrospective analysis of a longitudinally maintained institutional database maintained by individuals other than the treating surgeons to identify patients undergoing conversion of constrained liners to DM constructs in revision THA from 2011 to 2014. We identified 16 patients who underwent revision of dislocated constrained liners to DM constructs. Two patients died before 2-year followup, leaving 14 patients available for followup at a minimum of 24 months and a median of 37 months (range, 24-71 months). Indications for conversion to DM constructs included patients with dislocation of multiple prior constrained liners, patients with at least partial abductor functioning and soft tissue tensioning, and patients at very high risk for recurrent instability as an alternative to resection arthroplasty. Ten patients (10 of 14) underwent DM conversion at the time of cup revision, whereas four patients (four of 14) had a DM construct cemented into a preexisting cup. Median age was 65 years (range, 53-93 years). Median number of prior hip surgeries was five (range, three to 10) and seven patients (seven of 14) had dislocated more than one constrained liner.

RESULTS

Harris hip score improved from a median of 57 (range, 55-67) to 84 (range, 68-96) postoperatively (p < 0.001). Three patients (three of 14) experienced a redislocation. Two (two of 14) of these patients were closed reduced and treated successfully nonoperatively; one (one of 14) patient experienced an intraprosthetic dislocation and underwent modular exchange. One patient (one of 14) underwent early resection arthroplasty for acetabular loosening after complex acetabular reconstruction. Overall, all other patients (13 of 14) retained a DM construct at final followup.

CONCLUSIONS

Conversion to a DM construct shows promise as a salvage option in high-risk, multiply operated on patients with dislocated constrained liners undergoing revision THA for recurrent instability. The ability to close reduce a dislocated DM construct is a distinct advantage over constrained liners. However, longer followup is required given that three of 14 redislocated, and one of those underwent revision for persistent instability at short-term followup.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Constrained Acetabular Components Used in Revision Total Hip Arthroplasty: A Registry Analysis

BACKGROUND

Constrained acetabular components have a mechanism to lock in the femoral head. They have been developed to control postoperative dislocation, particularly in revision total hip arthroplasty (THA). Although these components may reduce dislocation, there are durability concerns: with reports of locking mechanism failures and loosening. We wanted to determine the outcome of constrained components in controlling dislocation, and if these components had a higher rate of second revision when compared with standard nonconstrained components.

METHODS

Revision THA procedures from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) with a recorded primary procedure and initial diagnosis of osteoarthritis were used to compare constrained and standard nonconstrained components. Kaplan-Meier estimates of survivorship were calculated, and hazard ratios using Cox proportional hazard models were used to compare groups.

RESULTS

There were 9509 THA first-revision procedures and 700 constrained components. Constrained components had a significantly higher revision rate after 3 months when large-head metal-on-metal components were included (hazard ratio = 1.37; P = .005). When large-head metal-on-metal components were excluded, there was no difference in the rate of second revision between the 2 groups. When the analysis was limited to first revision for dislocation, constrained components had a higher second revision rate for further dislocation after 9 months.

CONCLUSION

Constrained acetabular components had similar second-revision rates when compared with standard nonconstrained components, both for all first-revision reasons and when used to treat dislocation. Although possibly used for the more difficult unstable hips, constrained components had a higher rate of second revision for further dislocation.

Outcomes of total hip replacement in limbs affected by poliomyelitis

INTRODUCTION

The outcomes of total hip replacement in patients suffering from residual poliomyelitis are poorly covered in the literature. In this retrospective study we posed the question of whether total hip replacement performed for degenerative hip diseases in limbs with residual poliomyelitis could determine satisfactory mid-term clinical and radiographic results, with a reasonable complication rate.

METHODS

A retrospective study was carried out to assess the results of 14 total hip replacements performed on 14 patients with residual poliomyelitis on the involved limb from June 1999 to September 2011. Average age at the time of surgery was 51 years (range 26-66 years). Mean duration of follow-up was 92 months (range 52-156 months). Surgery was performed through a direct lateral approach on all hips. All but one were cementless implants.

RESULTS

2 implants failed, 1 due to traumatic acetabular fracture 6 days after surgery, and 1 due to aseptic cup loosening 13 years after surgery. Surgery was uneventful in all patients except 1 (7%), who experienced a transient sensory sciatic nerve palsy. At the latest follow up Harris Hip Score was 83.3 (range 72-91) with a marked improvement when compared to preoperative score (average 52, range 32-78). No dislocations had occurred.

CONCLUSIONS

Total hip replacement can be considered a feasible option for hip osteoarthritis in patients with limbs affected by residual poliomyelitis. Longer follow-up studies are needed to assess the effectiveness of unconstrained total hip replacement in polio patients.

Outcome of Revision Total Hip Arthroplasty in Management of Failed Metal-on-Metal Hip Arthroplasty

BACKGROUND

This is a retrospective review of the functional outcomes and complications of revision total hip arthroplasty (THA) of failed metal-on-metal (MoM) hip arthroplasty.

METHODS

A total of 20 revision THAs were performed in 19 patients. Of them, 2 cases were failed hip resurfacing, and 18 cases were failed (MoM) THA. The mean age at revision (THA) was 59.35 years (standard deviation [SD] 9.83).

RESULTS

The mean follow-up was 45 months (SD 13.98). The indications of revision were aseptic loosening of acetabular component without adverse local tissue reaction (ALTR; 10 hips), aseptic loosening of the acetabular and femoral components without ALTR (1 hip), painful hip associated with ALTR (6 hips), iliopsoas impingement associated with a large-diameter femoral head or malpositioned acetabular component (3 hips). The acetabular components were revised in 18 hips using Trabecular Metal Modular cups. The femoral components were revised in 3 hips. A constrained acetabular liner was used in 5 hips. The Harris hip score significantly improved from 48.4 (SD 12.98) to 83.25 (SD 10.08). There were 2 complications (1 foot drop and 1 superficial infection) and 1 failure (recurrent dislocation) that required revision to a constrained liner.

CONCLUSION

Early results of revision THA of failed MoM hip arthroplasty showed improvement in pain and functional outcome. No case of failed bone ingrowth was noted with the use of Trabecular Metal Modular cups. Extensive soft tissue and abductor muscles dysfunctions were common. A constrained acetabular component with repair of the hip abductors might be beneficial.

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.

High Failure Rate of Modular Exchange With a Specific Design of a Constrained Liner in High-Risk Patients Undergoing Revision Total Hip Arthroplasty

BACKGROUND

Addressing recurrent instability in patients with poor bone stock and inadequate abductor tensioning remains a challenge in revision total hip arthroplasty. One treatment method is implantation of a constrained liner. The purpose of this study was to determine clinical outcomes, redislocation rate, and revisions of a focally constrained liner in a high-risk patient cohort.

METHODS

Fifty-eight hips between 2008 and 2011 underwent implantation of a focally constrained liner. Nineteen were placed concurrent with acetabular component revision and 39 were placed into a well-fixed acetabular shell. Mean age was 69 years and mean number of previous ipsilateral hip surgeries was 4.2. At mean follow-up of 3.5 years, we analyzed clinical outcomes, redislocation, and revisions.

RESULTS

Mean Harris Hip Scores was 74. Fourteen hips (24%) were revised and 3 hips (5%) required reoperation at final follow-up. Eleven hips (19%) redislocated at a mean time to dislocation of 12.2 months; 31% (11 of 36 patients) that underwent modular exchange specifically for instability redislocated. Risk factors for redislocation included number of previous surgeries (P = .013), implantation of a 28 mm femoral head (hazards ratio 12.8), revision indication of instability (P = .04), and modular exchange with constrained liner implantation without acetabular shell revision (P = .01).

CONCLUSION

Implantation of a focally constrained liner in revision total hip arthroplasty for recurrent instability has a high failure rate, especially with a modular exchange. Although concurrent acetabular revision had a lower redislocation rate, the decision to revise a well-fixed cup should be weighed with potential complications associated with cup revision.

Freedom Constrained Liner for the Treatment and Prevention of Dislocation in Total Hip Arthroplasty

BACKGROUND AND PURPOSE

Dislocation is one of the most common complications following total hip arthroplasty. The aim of our study was to assess failure rate of the Biomet Freedom constrained liner (Biomet, Warsaw, IN, USA) either in revision surgery for recurrent dislocation, or as a preventive method in high dislocation risk patients.

PATIENTS AND METHODS

We assessed retrospectively 105 consecutive surgical procedures in 103 patients where a Freedom constrained liner or cup was used in Turku University Hospital over a 7-year period from 2007 to 2014. The mechanical failure rate of the device was assessed based on medical records. The average age of the patients was 73.4 years. The number of male patients was 53 (51%). Mean follow-up time was 2.5 years. The association between failure of the device and potential risk factors-age, gender, indication, and approach-was analyzed with logistic regression. Results were expressed by odd ratios and 95% confidence intervals.

RESULTS

The mechanical failure rate of the Freedom device was 6 out of 105 (5.7%). None of the 11 preventive primary THAs against dislocation failed, 4 out of 52 (7.7%) preventive revision THAs against dislocation failed, and 2 out of 42 (4.8%) of the treated dislocation cases failed. Four out of six failures were dislocations due to impingement and failure of the locking mechanism. Two liners failed because of loosening. The risk factors assessed were not associated with failure of the device.

INTERPRETATION

We found out that the mechanical failure rate of a Freedom constrained device was low. These results encourage us to continue using the device.

Constrained captive acetabular cup for recurrent dislocation of hemiarthroplasty in elderly: A case series

INTRODUCTION

Hemiarthroplasty of the hip is one of the commonest procedures done for intracapsular fractures of the neck of femur in elderly. Dislocation of the hemiarthroplasty is a recognised and significant complication. This is associated with considerable morbidity and mortality. The treatment options include closed manipulation, skin and skeletal traction, conversion to total hip replacement, exploration and open reduction and leaving it out of the acetabulum.

PRESENTATION OF CASE

A retrospective review of ten patients with recurrent and failed closed manipulative reduction of hemiarthroplasty who underwent revision using a cemented captive acetabular cup and cement to cement revision of femoral component with Exeter CDH stem was carried out. The follow up period was two years and the functional outcomes were assessed using Harris hip scores.

DISCUSSION

The management of recurrent dislocations of hemiarthroplasty in elderly patient are very challenging. Even though various treatment options are described most of them are associated with increased morbidity and mortality and prevent these patients from early mobilisation. The use of captive acetabular avoid repeated dislocations, prolonged bed rest, wearing of a brace and all the complications associated with sustained immobilization. The drawbacks of using constrained cups are hip pain, limited hip movements and loosening.

CONCLUSION

We describe a new method of treatment of this difficult condition with a cemented constrained acetabular captive cup and cement to cement revision using a CDH femoral stem. This method prevents further dislocations and will give good functional outcomes thus reducing the high morbidity and mortality.

[Analysis of the failures of a cemented constrained liner model in patients with a high dislocation risk]

OBJECTIVE

To evaluate the short-term results of an ultra high molecular weight polyethylene retentive cup in patients at high risk of dislocation, either primary or revision surgery.

MATERIAL AND METHOD

Retrospective review of 38 cases in order to determine the rate of survival and failure analysis of a constrained cemented cup, with a mean follow-up of 27 months. We studied demographic data, complications, especially re-dislocations of the prosthesis and, also the likely causes of system failure analyzed.

RESULTS

In 21.05% (8 cases) were primary surgery and 78.95% were revision surgery (30 cases). The overall survival rate by Kaplan-Meier method was 70.7 months. During follow-up 3 patients died due to causes unrelated to surgery and 2 infections occurred. 12 hips had at least two previous surgeries done. It wasn't any case of aseptic loosening. Four patients presented dislocation, all with a 22 mm head (P=.008). Our statistical analysis didn't found relationship between the abduction cup angle and implant failure (P=.22).

CONCLUSIONS

The ultra high molecular weight polyethylene retentive cup evaluated in this series has provided satisfactory short-term results in hip arthroplasty patients at high risk of dislocation.

Component selection in revision total hip arthroplasty

Component selection for revision total hip arthroplasty is important for creating a stable hip, providing offset to maximize joint mechanics, and restoring appropriate leg lengths. On the femoral side, fully porous coated stems, modular tapered stems, and proximal femoral replacements can be used depending on the level of bone loss. For the acetabulum, smaller defects can be contained using second-generation porous coating hemispherical cups, whereas larger acetabular defects can be contained with cup cages, cages, or custom triflange implants. In addition, acetabular liners can improve stability through altered cup version, dual mobility, or constraint of the femoral head.