Well-fixed Acetabular Component Research Articles

Cementation of a Metal Dual Mobility Liner in Patients Undergoing Revision Total Hip Arthroplasty

BackgroundDual mobility liners for primary and revision total hip arthroplasties can lead to decreased dislocation and revision rates. However, there are a lack of data analyzing their utilization when cementing into well-fixed acetabular components in a variety of scenarios. Therefore, the purpose of this study was to examine cementation of dual mobility liners into well-fixed existing acetabular components from previous hip procedures, into new acetabular components, or directly into the acetabulum without prior implants. We specifically aimed to assess the following: (1) aseptic revision-free implant survivorship, (2) patient-reported outcomes, (3) prosthetic joint infections, dislocations, and osteolysis, (4) medical complications and readmissions, and (5) radiographic outcomes. MethodsA total of 35 patients who underwent treatment with a cemented dual mobility liner from October 1, 2014, to July 1, 2018, were identified and followed up for a mean of 4 years (range, 4-8). The primary outcome of interest was revision-free survival. The secondary outcomes included patient-reported outcome measurements, dislocations, periprosthetic infections, periprosthetic fractures, pulmonary emboli, deep vein thromboses, radiographic osteolysis, and emergency visits as well as inpatient admissions. The patient-reported outcome measurements used were the Hip Disability and Osteoarthritis Outcome Score for Joint Replacement, Short-Form 12 Health Survey Mental Component, and Short-Form 12 Health Survey Physical Component. ResultsAseptic revision-free survivorship was 93.3%, 92.3%, and 100% for previous acetabular cup, new cup, and native acetabulum, respectively. The Hip Disability and Osteoarthritis Outcome Score for Joint Replacement improved and the Short-Form 12 Physical Component improved postoperatively for all groups. Surgical complications included 3 prosthetic joint infections (1 in a new cup and 2 in native acetabula). A total of 1 patient (previous cup) had an emergency visit and inpatient readmission. Only 1 cemented dual mobility recipient (new cup) demonstrated progressive acetabular radiolucencies and all cemented dual mobility patients had no evidence of acetabular subsidence. ConclusionsCemented dual mobility bearing liners demonstrated exceptional survivorship, low complication rates, adequate radiographic results, and improved functional outcomes when cemented into previously inserted well-fixed acetabular components, new components, or native acetabula. To the best of the authors’ knowledge, this is the first study to demonstrate success at a minimum of 4-year follow-up. These data are important to surgeons deciding on the appropriate implantation methods to use for their high-risk patients.

Is Retention of the Acetabular Component at Revision Surgery a Long-Term Solution?

Acetabular retention in revision total hip arthroplasty (THA) may be advantageous, yet long-term survival data is limited. Thus, we investigated long-term survivorship of retained acetabular components in revision THA with analysis of rerevision rate, instability risk, and clinical outcomes. We reviewed 98 hips with polyethylene wear and/or osteolysis that were revised with retained acetabular components. Acetabular inclination and anteversion were measured from prerevision radiographs. A retrospective chart review was performed, collecting outcomes of interest including Harris hip score, instability events, and rerevision surgery. Kaplan-Meier analysis was used to calculate the risk of revision over time. Predictors of survival including acetabular component position were analyzed by multiple logistic regression. Average follow-up was 13 years (range, 5-24). Survivorship rates at 5, 10, 15, and 20 years were 89.7%, 81.6%, 70.8%, and 63.8%, respectively. There was improvement in average Harris hip score (61 to 76, P < .0001). There was a 9% rate of dislocation, and 6 hips (6%) were rerevised for recurrent instability. Overall, there were 23 (23%) rerevisions at an average of 6.1 years with the most common reasons being instability (6%) and aseptic loosening (6%). Use of conventional polyethylene was the only identified independent predictor of rerevision (P= .025). Retention of a well-fixed acetabular component in revision THA provides acceptable long-term outcomes with a 15-year survivorship of 71%. Instability and aseptic loosening were the most common reasons for rerevision. Surgeons may consider retaining the acetabular component at revision surgery if the implant is well-fixed and well-positioned.

Long-Term Outcomes of Cementing Highly Cross-Linked Polyethylene Liners Into Well-Fixed Acetabular Shells in Revision Total Hip Arthroplasty

BackgroundCementing a new liner into a secure, well-positioned metallic shell can be a less-invasive strategy in revision total hip arthroplasty (THA). This study aimed to report the mean 14-year outcomes of cementing highly cross-linked polyethylene (XLPE) liners into well-fixed acetabular shells in revision THAs. MethodsThis study reviewed a single-surgeon series of cementing XLPE liners into well-fixed acetabular components. Of the 52 hips (51 patients) evaluated, 48 hips (47 patients) that satisfied a minimum follow-up of 10 years were included. The Harris Hip score was used for clinical evaluation. Final hip radiographs were used to determine the extent of acetabular osteolysis and stability of the components. The mean age at index operation was 53 years (range, 32 to 72). The mean follow-up duration was 14 years (range, 10 to 18). ResultsThe mean Harris Hip score improved from 58 points (range, 23-81) preoperatively to 91 points (range, 45-100) at the final evaluation (P < .001). A total of 3 acetabular rerevisions were performed, all for aseptic loosening of the outer shell. One postoperative dislocation occurred, but it was successfully treated with a closed reduction. Final radiographs showed a significant reduction in acetabular osteolysis (P < .001). Implant survivorship free from any rerevision was 93.3% (95% confidence interval, 85.9-100%) at 14 years. ConclusionCementing an XLPE liner into a well-fixed acetabular shell in revision THA demonstrated excellent clinical and radiographic outcomes at a mean of 14 years postoperatively. This technique could be a safe and durable option in the absence of XLPE liners compatible with preimplanted shells.

Cementation of a dual mobility cup in a well-fixed acetabular component- a reliable option in revision total hip arthroplasty?

BackgroundThe “cup-in-cup” technique allows for revision of failed total hip arthroplasty (THA) when the cementless cup is well fixed. Furthermore, it can be used for liner wear or mechanical failure where liner replacement may be impossible or impractical. Recently, the “cup-in-cup” technique in combination with dual mobility cups (DMC) has drawn increased attention. Our aim was to report on the clinical and radiographic outcomes following this surgery.MethodsFrom 2015 to 2020, 33 patients treated with the DMC- “cup in cup” technique were retrospectively reviewed. Fourteen patients had died while 19 were available for the final follow-up (FU), of which 15 underwent both a radiograph and a FU visit, 2 underwent a radiograph only and 2 underwent a telephone interview only. Patient-related outcome measures included the HHS and the WOMAC. Radiographs were assessed for implant loosening and positioning. Primary endpoint was revision of any cause and secondary endpoint was loosening of the DMC at the latest FU. The survival analysis was conducted using the Kaplan-Meier method.ResultsThe mean age at surgery was 78.6 ± 7.1 (63–93) years and the mean surgery duration was 124.4 ± 52.0 (60–245) minutes. Recurrent dislocation (42.4%), periprosthetic fracture (39.4%) and polyethylene wear (6.1%) were the most frequent reasons for surgery. The mean FU duration (n = 19) was 28.5 ± 17.3 (3–64) months. The mean HHS score at FU was 59.4 ± 22.2 (29–91) and the mean WOMAC score was 59.7 ± 25.6 (15.6–93.8).Two cups were revised due to instability and one revision was performed due to periprosthetic joint infection, accounting for an overall cup survival rate of 86.8% after a mean FU of 22.9 ± 18.0 (1.5–64.6) months. The survival rate free of loosening was 90.9% after a mean FU of 22.3 ± 18.5 (1.5–64.7) months.ConclusionsWe found that the cementation of a DMC in a well-fixed cup is a promising short- to mid-term treatment addressing THA instability especially in elderly and frail patients, who benefit from a reduced operation time. Proper cementation technique, adequate cup positioning as well as selection of a sufficiently large DMC are crucial for treatment success. Longer FUs will be needed in the future in order to further prove the benefit of this technique.

Pearls: Removing Modular Metal-on-Metal Liners using a Battery-powered Handheld Impaction System.

The number of dislocations following THA is increasing in tandem with the increased number of primary and revision THAs being performed [2, 4]. Dual mobility (DM) articulations can address this complication by allowing the use of larger diameter femoral heads [5], which may contribute to a reduced risk of dislocation associated with DM components. Perhaps for these reasons, the use of DM implants in both primary and revision THA is increasing as well [1, 3, 6-8]. Most DM implants used in the United States employ a modular cobalt chrome liner that engages the acetabular shell with a mated Morse taper. In order to perform acetabular revision on one of these modular components, the modular liner must first be dissociated from the acetabular component. Many manufacturers provide instruments or technique suggestions, but despite these, dissociating a modular DM liner from its shell can be very difficult to do. Design-specific challenges, mechanical and chemical degeneration resulting in cold welding, and corrosion causing abnormal mating of the taper interface can make these liners resistant to removal. We propose a liner removal technique that makes it easier. Techniques to loosen the taper engagement of modular cobalt chrome bearings typically involve introducing mechanical vibration to the rim or face of the acetabular component to disengage the taper using tamps or extractor “plates” [9]. This can be challenging because the force and frequency of vibration required to disengage the liner may be inconsistent and unpredictable. We found that a battery-powered, handheld impaction system (Fig. 1) provides vibration with consistent and sufficient force, frequency, and direction to loosen the modular taper junction of modular DM liners or modular metal liners without damaging the existing well-fixed acetabular shell behind the liner. The battery-powered, handheld impaction system is a standard device that is made by any of the companies that offer drill/reamer power kits.Fig. 1: The battery-powered, handheld impaction system is shown. The system shown here is provided free of charge with the DePuy primary hip system. This particular system offers several modular attachments that can be used for THA. We utilized the bullet tip attachment for this technique.To use this system, we perform a revision approach to the hip of the surgeon’s choosing, and following removal or retraction of the femoral component, we obtain adequate exposure of the acetabular component. We then position the handheld system with the tip of the adaptor on the exposed rim of the acetabular component (Fig. 2). This system typically uses an adapter to attach to the acetabular component and femoral broaches; however, a bullet tip adapter that does not require component attachment is also available. In the example depicted here, we demonstrate the bullet tip stem insertion adaptor provided by the manufacturer. After several (three to five) consistent strikes to the rim of the acetabular component, the liner usually is unseated from the acetabular shell behind it, and its displacement is both visible (Fig. 3) and palpable to the surgeon.Fig. 2: The bullet tip for the impaction system is positioned on the rim of the well-fixed acetabular component after full exposure.Fig. 3: In some cases, the cobalt chrome liner can be visualized to disengage from the acetabular component. In this view, the liner is no longer sitting flush with the rim of the component, indicating disengagement.In modular DM design in this demonstration, the liner frequently seats flush with the rim of the component, making it difficult to grasp the liner for removal from the shell even after it is unseated. Sometimes, though, visual disengagement is not clearly observed; however, in our experience, three to five taps is enough to disengage it. Therefore, in our technique, we would either use a suction device provided by the manufacturer (Fig. 4) or the suction provided by the pulse irrigation system to grasp the liner and remove it from the component (Fig. 5). Once the liner has been removed, the surfaces of the shell and liner can be assessed for corrosion and the revision operation can proceed as planned. We have successfully used this technique to remove the modular DM liner from a number of different manufacturers and modular metal liners from metal-on-metal THA with similar consistency and success.Fig. 4: A suction device is utilized to grasp the unseated liner for removal.Fig. 5: The liner is removed after it is unseated using the suction device.

Outcomes of Cementing an Acetabular Liner into a Secure Shell Over Time: Commentary on an article by Nicholas A. Bedard, MD, et al.: "Intermediate to Long-Term Follow-up of Cementing Liners into Well-Fixed Acetabular Components".

Outcomes of Cementing an Acetabular Liner into a Secure Shell Over Time: Commentary on an article by Nicholas A. Bedard, MD, et al.: "Intermediate to Long-Term Follow-up of Cementing Liners into Well-Fixed Acetabular Components".

Intermediate to Long-Term Follow-up of Cementing Liners into Well-Fixed Acetabular Components.

The cementation of a new liner into a well-fixed acetabular component is common during revision total hip arthroplasty (THA) for many indications, but most commonly for lack of a modern, compatible, highly cross-linked polyethylene (HXLPE) liner. However, little is known about the intermediate-term to long-term durability of this strategy. The purpose of this study was to evaluate the implant survivorship, risk of complications, clinical outcomes, and radiographic results of cementing a new HXLPE liner into a well-fixed acetabular component. We retrospectively identified 323 revision THAs in which a nonconstrained HXLPE liner was cemented into a well-fixed acetabular component. The mean age at the time of the revision THA was 63 years, and 50% of patients were female. The most common indications for revision THA were polyethylene wear and osteolysis (48%), aseptic femoral loosening (35%), and hip instability (8%). The mean follow-up was 9 years. Polyethylene liner failure occurred in 11 cases (3%). In all cases, the cemented liner dissociated from the acetabular component. At 10 years, the survivorship free from any revision was 80% (95% confidence interval [CI], 75% to 84%) and the survivorship free from any reoperation was 77% (95% CI, 72% to 82%). The most common reason for re-revision was dislocation (45% of reoperations). A dislocation occurred in 17% of cases. Hips that underwent revision for instability were significantly more likely to dislocate compared with hips that underwent revision for liner wear (hazard ratio [HR], 2.3 [95% CI, 1.2 to 4.5]; p = 0.02). Elevated rim or face-changing liners were significantly more likely to dissociate than flat liners (HR, 9.0 [95% CI, 1.2 to 70.6]; p = 0.04). Cementation of a nonconstrained HXLPE liner into a well-fixed acetabular component during revision THA provided durable fixation with only a small number of failures at the cement interface (3%). Instability after this procedure remains a concern, but this is multifactorial in nature. These data support the continued use of this technique, when necessary, during revision THA. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A Novel Method of Determining Acetabular Component Size to Guide Explant in Revision Hip Arthroplasty.

Revision hip arthroplasty is a frequently performed procedure and is projected to increase annually. Removal of a well-fixed acetabular component can involve loss of much needed bone stock. Contemporary instruments allow acetabular removal with minimal morbidity; however, their use requires accurate knowledge of the component size. We describe a technique that allows sizing to be determined accurately, without specialized equipment, in situations where component details are unavailable. Our technique multiplies ratio of head:cup on pre-operative X-ray by the diameter of the index femoral head which is removed intra-operatively to predict index cup size. This novel surgical technique appears accurate in prediction of cup size to guide explant in revision hip arthroplasty.

A Comparative Study Between the Stryker EZout Powered Acetabular Revision System and the Zimmer Explant Acetabular Cup Removal Systems

The conservation of bone stock and the decrease of intraoperative acetabular fracture risk associated with revision surgery is a primary goal to improve the outcome of the procedure. The objective of this study was to evaluate and compare the performance of the Explant Acetabular Cup Removal System and the EZout Powered Acetabular Revision System in an in vitro model. Acetabular components were implanted into instrumented composite hemipelvises and divided into 2 groups, EZout System and Explant System. One experienced orthopedic surgeon and 1 orthopedic resident physician performed the removal procedures. The strains at various points in the periacetabular bone, the temperature at the implant-bone interface, the total time to removal, the torque applied to the implant and the amount of acetabular foam on each cup after extraction, as a surrogate for cavitary acetabular bone stock loss, were calculated for each test. Statistical analysis was conducted using 2-way multivariate analysis of variance followed by Tukey honestly significant difference multiple comparisons. The EZout System required an overall lower force and torque (P&lt;0.0001, both) during removal, producing lower strains in the surrounding composite bone. The procedure was faster (P&lt;0.0001) and less energy demanding with the EZout compared with the Explant. The amount of foam on the cup was on average less for the EZout than for the Explant (P&lt;0.05). We found that the EZout System is effective in achieving safe removal of a well-fixed acetabular component in an in vitro model of cementless fixation. This system should be considered as a reasonable alternative to manual removal techniques.

Fate of the Retained Acetabular Component During Revision Total Hip Arthroplasty: A Meta-Analysis and Systematic Review

BackgroundThe aim of this meta-analysis and systematic review is to estimate re-revision rates due to aseptic loosening of retained acetabular components after revision total hip arthroplasty. MethodsPubMed, EMBASE, Cochrane Library, and Web of Science were searched until June 11, 2018. Data were extracted by 2 independent investigators and consensus was reached with the involvement of a third investigator. Rates of re-revision due to aseptic loosening from 6 studies were aggregated using random effects model after a logit transformation and were grouped by study and population level characteristics. ResultsAn assessment of the re-revision rates of retained acetabular components due to aseptic loosening in revision total hip arthroplasty was reported in 6 studies involving 669 cases. The pooled re-revision rate was 12.6% (95% confidence interval 8.4-18.4) with a mean study follow-up of 8.6 years. The rate of re-revision due to aseptic loosening of retained acetabular components was 6.8% (95% confidence interval 3.4-13.3). In the univariate meta-regression analysis, mean age at index revision surgery was significantly associated with the rate of re-revision due to aseptic loosening (R2 = 99.98%, P < .0001). ConclusionBased on this exploratory analysis, revision hip procedures with retentions of well-fixed acetabular components generally have a low risk of failure during mid-term to long-term follow-ups.

Long-Term Outcomes of Constrained Liners Cemented into Retained, Well-Fixed Acetabular Components

Cementation of a constrained liner is a viable option for treating instability after total hip arthroplasty (THA) when the acetabular component is well fixed and well aligned. However, concerns regarding long-term mechanical failure and recurrent instability remain. The aim of this study was to evaluate the long-term survivorship, complications, and clinical and radiographic outcomes of constrained polyethylene liners cemented into well-fixed acetabular components at the time of revision THA. We identified 125 cases in which a constrained liner of 1 design was cemented into a retained, osseointegrated acetabular component during revision THA between 1998 and 2006. The mean patient age at revision was 70 years. Mean follow-up was 7 years. Survivorship data, risk of instability, and clinical and radiographic outcomes were analyzed. Survivorship free from revision for instability was 86% at 5 years and 81% at 10 years. Survivorship free from aseptic acetabular component revision was 78% at 5 years and 65% at 10 years, with the most common failure mechanism being dissociation of the constrained liner from the acetabular component. Survivorship free from revision for any reason was 76% at 5 years and 60% at 10 years. The most common complications were instability and periprosthetic joint infection, with cumulative incidences at 7 years of 18% and 11%, respectively. Harris hip scores did not significantly improve. Cup position did not affect implant survivorship or risk of dislocation. Cementing a constrained liner into a retained acetabular shell at the time of revision THA has durable long-term results, with 8 in 10 patients free from instability at 10 years. Aseptic acetabular survivorship was worse (65%) at 10 years, primarily due to dissociation of the constrained liner from the acetabular component. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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

BackgroundRecurrent 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. MethodsEighteen 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). ResultsNo 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). ConclusionCementation 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.

Salvage of a monoblock metal-on-metal cup using a dual mobility liner: a two-year MRI follow-up study.

Revision of failed modular metal-on-metal total hip replacement (MoM-THA) can be technically difficult. A dual mobility liner can help to salvage a well-fixed acetabular component. The present paper reports the clinical and radiographic outcome of revision of failed Birmingham modular MoM-THA using a dual mobility liner. The present study reports on ten patients (3 female and 7 male) with 11 revision THAs. Patients underwent revision an average of 51months (range 40-73months) after index procedure. Mean follow-up after the revision was 31months (range 24-37months) and all patients underwent an MRI with metal artifact reduction software (MARS) at least twoyears after revision to assess for local polyethylene wear and osteolysis. The Harris Hip score improved from 92.2 (range 63.0-100.0) to 100.0 (p=0.072). One patient had a one-time dislocation within sevendays of surgery. No patient required additional surgeries. Radiographs showed no signs of component loosening and osteolysis and MRI imaging revealed no evidence of polyethylene wear or osteolysis. A dual mobility liner in an existing Birmingham cup can provide excellent clinical and radiological short-term results without MRI evidence of increased polyethylene wear. Post-operative hip precautions should be enforced.

Revision Total Hip Arthroplasty in the Setting of a Well-Fixed Cup: Early Report on the Cup-in-Cup Technique

AbstractWhen faced with a well-fixed acetabular component during revision total hip arthroplasty (THA) in the setting of recurrent instability, reconstructive options are limited, and consequences can prove dire if removal leads to severe bone loss or pelvic discontinuity. Our aims are to report the surgical technique, early survivorship, radiographic improvements, and complications on a consecutive, retrospective series of 13 hips in 12 patients who were treated with a cup-in-cup surgical technique to address multiply recurrent dislocations in the setting of a well-fixed cup. If determined to be stable and acceptably positioned upon intraoperative assessment, the acetabular component is retained, a second shell is cemented into the preexisting cup, and a dual mobility or standard polyethylene liner bearing is utilized. At 2-year minimum follow-up, the cup-in-cup arthroplasty exhibited an overall 85% survivorship. Two subjects required subsequent revisions: one for infection and one for ongoing instability in the setting of general noncompliance. No revisions were performed for loosening of the cup-in-cup interface. The median affected leg length was increased by 2.8 mm (p = 0.04) and horizontal offset improved by an average of 6.9 mm (p &lt; 0.001). There were a total of four dislocations in two subjects after cup-in-cup revision arthroplasty with no failures at the cup–cup cement interface. Our series demonstrates acceptable early outcomes in terms of improved stability and decreasing the need for further revision surgery while utilizing the cup-in-cup revision arthroplasty technique in situations of recurrent dislocations.

Isolated Head and Liner Exchange in Revision Hip Arthroplasty.

As the number of primary total hip arthroplasties increases, so does the burden of revision procedures. The decision to revise well-fixed components in the setting of polyethylene wear and osteolysis is controversial. Modular head and liner exchange offers the advantages of reduced invasiveness, faster recovery, and bone preservation. These advantages come at the expense of higher rates of revision surgery for instability. Using the native locking mechanism for securing the new liner is preferred; however, cementing a liner into a well-fixed acetabular component is a practical alternative. The use of bone allograft or bone graft substitute for areas of osteolysis is controversial. In the setting of osteolysis, outcomes associated with the use of highly cross-linked polyethylene liners have been better than those associated with the use of conventional polyethylene; therefore, thinner liners and larger femoral heads can be used and reduce the risk of instability.

Cementing a polyethylene cup into a well fixed acetabular metal-on-metal resurfacing component? An experimental investigation.

Adverse reactions to metal debris often indicate revision surgery in metal-on-metal (MoM) hip arthroplasty and an exchange of the MoM bearing into either a metal on polyethylene or a ceramic-on-polyethylene articulation. At the moment the removal of the entire implant system is the most reasonable method. In order to avoid bone loss caused by the removal of a well-fixed acetabular component, the purpose of this study was to measure the stability of a cemented polyethylene (PE) cup in an acetabular hip resurfacing component and to examine if such a method could be suitable for clinical use. PE cups were cemented into 2 different hip resurfacing components and biomechanical tests were applied to measure failure torques under lever out and rotational load. In all cases failure of the interface between the resurfacing components and the cement layer occurred at a very low load (0.14 Nm-61.50 Nm). The early failure occurred due to lacking interdigitation of cement and the polished metal surface. Thus we warn against cementing a PE cup into acetabular hip resurfacing components for clinical use.

A simple technique to remove well-fixed acetabular components in revision of total hip arthroplasty

Removing well-fixed acetabular components can be a challenge for orthopaedic surgeons in revision of total hip arthroplasty. Acetabular bone loss, fracture, and other complications occurred in extracting implants may result in instability and fail of revision. Thus, instruments are developed to avoid such complications. We report a simple technique by drilling a tunnel on the superolateral quadrant of acetabulum and using an offset staff to remove acetabular components without many matching units. The procedure of removing well-fixed acetabular components is a simple, efficient, inexpensive, bone stock preserving technique.

Revision Total Hip Arthroplasty for Fractured Ceramic Bearings: A Review of Best Practices for Revision Cases

BackgroundTotal hip arthroplasty revision for a fractured ceramic bearing is rare but offers unique challenges. The purpose of this review was to provide a summary of existing literature on fractured ceramic bearings. MethodsTwo authors performed a literature search of the MEDLINE OVID and PubMed databases with the following search terms: ceramic, fracture, total hip arthroplasty, and revision. ResultsThe search identified 228 articles of which 199 were selected for review. ConclusionsIt is mandatory to perform a complete synovectomy and thorough debridement of the fractured ceramic fragments. A well-fixed acetabular component should be removed if either the locking mechanism is damaged or the component is malpositioned. If the femoral stem taper is damaged, the femoral stem should be removed. However, if minimal damage is present, the femoral stem may be retained and revised using a fourth generation ceramic head with a titanium sleeve. Metal bearings should be avoided and revision with ceramic bearings should be performed whenever possible.

Un essai pilote comparant le comportement à l’arrachement des cupules metal-back vissantes et cimentées en polyéthylène : étude cadavérique cas témoin

BackgroundThe removal of well-fixed acetabular components following total hip arthroplasty (THA) is a difficult operation and could be accompanied by the loss of acetabular bone stock. The optimal method for fixation is still under debate. The aim of this pilot study was to compare the tear-out resistance and failure behavior between osseo-integrated and non-integrated screw cups. Furthermore, we examined examined whether there are differences in the properties mentioned between screw sockets and cemented polyethylene cups. HypothesisTear-out resistance and related mechanical work required for the tear-out of osseo-integrated screw sockets are higher than in non-integrated screw sockets. Patients and methodsTen human coxal bones from six cadavers with osseo-integrated screw sockets (n=4), non-integrated (implanted postmortem, n=3) screw sockets and cemented polyethylene cups (n=3) were used for tear-out testing. The parameters axial failure load and mechanical work for tear-out were introduced as measures for determining the stability of acetabular components following THA. ResultsThe osseo-integrated screw sockets yielded slightly higher tear-out resistance (1.61 ± 0.26kN) and related mechanical work compared to the non-integrated screw sockets (1.23 ± 0.39kN, P=0.4). The cemented polyethylene cups yielded the lowest tear-out resistance with a failure load of 1.18±0.24kN. Compared to the screw cups implanted while alive, they also differ on a non-significant level (P=0.1). Osseous failure patterns differed especially for the screw sockets compared to the cemented polyethylene cups. DiscussionOsseo-integration did not greatly influence the tear-out stability in cementless screw sockets following axial loading. Furthermore, the strength of the bone–implant interface of cementless screw sockets appears to be similar to cemented polyethylene cups. However, given the high failure load, high mechanical load and because of the related bone failure patterns, removal should not be performed by means of tear-out but rather by osteotomes or other curved cutting devices to preserve the acetabular bone stock. Level of evidenceLevel III, case-control-study.

A pilot trial comparing the tear-out behavior in screw-sockets and cemented polyethylene acetabular components – a cadaveric study

BackgroundThe removal of well-fixed acetabular components following THA (total hip arthroplasty) is a difficult operation and could be accompanied by the loss of acetabular bone stock. The optimal method for fixation is still under debate. The aim of this pilot study was to compare the tear-out resistance and failure behavior between osseo-integrated and non-integrated screw cups. Furthermore, we examined whether there are differences in the properties mentioned between screw sockets and cemented polyethylene cups. HypothesisTear-out resistance and related mechanical work required for the tear-out of osseo-integrated screw sockets are higher than in non-integrated screw sockets. Patients and methodsTen human coxal bones from six cadavers with osseo-integrated screw sockets (n=4), non-integrated (implanted post-mortem, n=3) screw sockets and cemented polyethylene cups (n=3) were used for tear-out testing. The parameters axial failure load and mechanical work for tear-out were introduced as measures for determining the stability of acetabular components following THA. ResultsThe osseo-integrated screw sockets yielded slightly higher tear-out resistance (1.61±0.26kN) and related mechanical work compared to the non-integrated screw sockets (1.23±0.39kN, P=0.4). The cemented polyethylene cups yielded the lowest tear-out resistance with a failure load of 1.18±0.24kN. Compared to the screw cups implanted while alive, they also differ on a non-significant level (P=0.1). Osseous failure patterns differed especially for the screw sockets compared to the cemented polyethylene cups. DiscussionOsseo-integration did not greatly influence the tear-out stability in cementless screw sockets following axial loading. Furthermore, the strength of the bone-implant-interface of cementless screw sockets appears to be similar to cemented polyethylene cups. However, given the high failure load, high mechanical load and because of the related bone failure patterns, removal should not be performed by means of tear-out but rather by osteotomes or other curved cutting devices to preserve the acetabular bone stock. Level of evidenceLevel III, case-control-study.