Well-fixed Acetabular Shell Research Articles

Acetabular component liner exchange with highly crosslinked polyethylene for wear and osteolysis.

Isolated acetabular liner exchange with a highly crosslinked polyethylene (HXLPE) component is an option to address polyethylene wear and osteolysis following total hip arthroplasty (THA) in the presence of a well-fixed acetabular shell. The liner can be fixed either with the original locking mechanism or by being cemented within the acetabular component. Whether the method used for fixation of the HXLPE liner has any bearing on the long-term outcomes is still unclear. Data were retrieved for all patients who underwent isolated acetabular component liner exchange surgery with a HXLPE component in our institute between August 2000 and January 2015. Patients were classified according to the fixation method used (original locking mechanism (n = 36) or cemented (n = 50)). Survival and revision rates were compared. A total of 86 revisions were performed and the mean duration of follow-up was 13 years. A total of 20 patients (23.3%) had complications, with dislocation alone being the most common (8.1%; 7/86). Ten patients (11.6%) required re-revision surgery. Cementing the HXLPE liner (8.0%; 4/50) had a higher incidence of re-revision due to acetabular component liner-related complications than using the original locking mechanism (0%; 0/36; p = 0.082). Fixation using the original locking mechanism was associated with re-revision due to acetabular component loosening (8.3%; 3/36), compared to cementing (0%; 0/50; p = 0.038). Overall estimated mean survival was 19.2 years. There was no significant difference in the re-revision rate between the original locking mechanism (11.1%; 4/36) and cementing (12.0%; 6/50; p = 0.899). Using Kaplan-Meier survival analysis, the revision-free survival of HXLPE fixed with the original locking mechanism and cementing was 94.1% and 93.2%, respectively, at ten years, and 84.7% and 81.3%, respectively, at 20 years (p = 0.840). The re-revision rate and the revision-free survival following acetabular component liner exchange revision surgery using the HXLPE liner were not influenced by the fixation technique used. Both techniques were associated with good survival at a mean follow-up of 13 years. Careful patient selection is necessary for isolated acetabular component liner exchange revision surgery in order to achieve the best outcomes.

Cage Augmentation of the Retained Acetabular Shell with a Dual Mobility Cup using the Double Socket Technique

Introduction: Prevention of dislocation after total hip arthroplasty (THA) remains a topic of debate. There are various surgical options to manage hip instability such as large femoral heads, and constrained liners, although the best option to tackle this is still controversial. In revision scenarios with previous well-fixed acetabulum shells, the cementation of polyethylene liners or the cementation of dual mobility (DM) into a well-fixed acetabulum shell (Double Socket Technique) has been documented before. Here, we report a case of re-revision THA, where we have used the Double Socket Technique of retaining the previous well-fixed acetabular shell with the cementation of the DM cup along with an anti-protrusio cage inside the socket. To the best of our knowledge, this is the first such a case to be reported worldwide. Case Report: A 54-year-old male who underwent THA in 1990 and an acetabulum cup revision in 2003 presented to us with right hip pain. Radiographs showed Paprosky Type 3A femoral bone loss and polyethylene wear. Intraoperatively after removing the polyethylene liner, the acetabulum shell was found to be well fixed and therefore retained. To increase stability, an anti-protrusio cage was inserted over it and a DM cup was cemented onto it (double socket). The femoral stem was revised using Wagner stem and encerclage wires and a hook plate was used to stabilize the osteotomy site. Conclusion: This technique is a reliable option and helps shorten the surgical time and reduce the bone loss that can occur in extracting a well-fixed acetabulum shell. The use of a DM cup decreases the chances of instability compared to the cementation of polyethylene liners and decreases the high failure rate associated with the use of cementation of constrained liners. The addition of an anti-protrusio cage in addition to the Double Socket Technique increases the stability of the construct. Keywords: Anti-protrusio cage, Dual mobility, Double socket, Revision total hip arthroplasty, Well-fixed acetabulum

Cementing a Monoblock Dual-Mobility Implant into a Fully Porous Cup in Revision Total Hip Arthroplasty to Address Hip Instability: Surgical Technique.

Cementing a Monoblock Dual-Mobility Implant into a Fully Porous Cup in Revision Total Hip Arthroplasty to Address Hip Instability: Surgical Technique.

Hip & Pelvis

The June 2023 Hip & Pelvis Roundup360 looks at: Machine learning to identify surgical candidates for hip and knee arthroplasty: a viable option?; Poor outcome after debridement and implant retention; Can you cement polyethylene liners into well-fixed acetabular shells in hip revision?; Revision stem in primary arthroplasties: the Exeter 44/0 125 mm stem; Depression and anxiety: could they be linked to infection?; Does where you live affect your outcomes after hip and knee arthroplasties?; Racial disparities in outcomes after total hip arthroplasty and total knee arthroplasty are substantially mediated by socioeconomic disadvantage both in black and white patients.

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.

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.

Cementation of the highly cross-linked polyethylene liner into a well-fixed acetabular shell to treat patients with recurrent dislocation after total hip arthroplasty.

Cementation of a highly cross-linked polyethylene liner into a well-fixed acetabular shell provided a good durability for liner wear. However, its efficacy in treating recurrent instability due to malposition cup is less reported. The aim of this study is to evaluate the outcome of this surgical technique to treat hip instability. From 2009 to 2019, we have identified 38 patients who had been surgically treated for recurrent instability, including cementation liner (N=20) and revision cup (N=18) procedures. Patients were followed for a mean of 45.66months. We have recorded and analyzed all causes of implant failure including recurrent instability. Clinical outcomes were assessed including complication and Harris Hip Score (HHS) preoperatively and at the latest follow-up. Revision-free survivorship for any cause was 95.0% at 1year, and 84.4% at 5years in cementation liner group and 88.9% at 1year and 5years in revision cup group. Mean Harris hip score improved from 48.3 points preoperatively to 79.5 points at the last follow-up in cementation liner group and mean HHS improved from 43.3 points preoperatively to 77.2 points in revision cup group. There were two implant failures in each group, including one is due to persistent hip instability and the other is due to periprosthetic joint infection in the cementation liner group and two implant failure are due to persistent hip instability in the revision cup group. Functional scores and implant survival were similar in both groups. We demonstrated that orientation correction via the cementation of the polyethylene liner into well-fixed acetabular shell is a promising option to treat and prevent instability. Level of Evidence: Therapeutic Level IV.

Effect of liner offset and inclination on cement retention strength of metal-in-metal acetabular constructs: A biomechanical study.

Cementing metallic liners into well-fixed acetabular shells facilitates utilizing dual-mobility cups in revision total hip arthroplasty without shell replacement. The current biomechanical study investigated the effect of increasing cemented liner (a) inclination; and (b) offset on the cement retention strength measured as the lever-out moment at cement failure. Eighteen metallic liner prototypes were cemented into cluster-hole acetabular shells at variable inclinations (0°, 10°, and 20°) and offsets (0 and 10 mm) relative to the enclosing acetabular shell (6 groups; n = 3 constructs per group). The constructs were connected to a material testing frame, and lever-out failure moments were tested through an established protocol. Failure occurred at the liner-cement interface (18/18). There was no correlation between liner inclination and the lever-out failure moment (r = -0.327, P = .185). Liner offset demonstrated a strong negative correlation to mean lever-out failure moments (r = -0.788, P < .001). There was no significant difference between mean lever-out failure moments at variable liner inclinations, regardless of offset (P = .358). Greater liner offset was associated with diminished mean lever-out failure moments (P < .001). Compared with neutral (0° inclination, 0 mm offset), the maximum inclination and offset group had the lowest mean lever-out failure moment (P = .011). Cemented metal-in-metal constructs are significantly affected by the liner positioning. While a correlation between liner inclination and cement retention strength could not be asserted, cement retention strength is significantly diminished by increased liner offset.

Increasing Liner Anteversion Decreases the Interfacial Strength of Polyethylene Liners Cemented Into Titanium-Alloy Acetabular Shells

BackgroundAcetabular component positioning during revision total hip arthroplasty can be suboptimal. Cementation of an acetabular liner into a well-fixed acetabular shell can allow surgeons to correct component version and inclination without the need for extensive revision surgery and progressive pelvic bone loss. However, to date, it is unknown what degree of version can be corrected without sacrificing fixation strength of the construct. In this study, cemented liners were biomechanically evaluated at increasing degrees of liner anteversion. MethodsTwenty-five commercially available liners were cemented into acetabular shells at 0°, 10°, 20°, 30°, and 40° of liner anteversion, relative to the acetabular shell (n = 5 per group). Components were then fixed to a materials testing frame and evaluated via an established lever-out testing protocol. Test data were collected via test frame software for calculation of yield and maximum moments during biomechanical testing. ResultsWhen liners were cemented at 20°, 30°, and 40° of liner anteversion, a significant decrease in maximum fixation moment was found when compared liners cemented at both 0° and 10° (P < .05). A significant negative correlation was noted for both yield and maximum moments and increasing liner angle (r = −0.566; P = .011 and r = −0.604; P = .006, respectively). ConclusionBiomechanical data from our study suggest that a threshold of acceptable anteversion during revision total hip arthroplasty is <20°. However, further studies are warranted to continue evaluation of the potential clinical impact and long-term device performance in this setting.

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

BackgroundAddressing 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. MethodsFifty-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. ResultsMean 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). ConclusionImplantation 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.

Advances in Acetabular Reconstruction in Revision Total Hip Arthroplasty

As the incidence of primary and revision hip arthroplasty increases, the need for a comprehensive approach to acetabular revision cannot be overstated. In the presence of osteolysis, there is a substantial population of patients with a well-fixed acetabular shell. It will be helpful to orthopaedic surgeons to review the classification of acetabular defects, techniques for exposing an acetabular component when the femoral component will be retained, methods of facilitating access to osteolytic lesions, the principles of bone grafting, options for liner fixation, and when removal of a well-fixed shell is necessary.

Medium-Term Results of Cementation of a Highly Cross-Linked Polyethylene Liner Into a Well-Fixed Acetabular Shell in Revision Hip Arthroplasty

The present study was undertaken to document outcomes of cementation of a highly cross-linked polyethylene (PE) liner into a well-fixed acetabular metal shell in 36 hips. All operations were performed by a single surgeon using only one type of liner. Patients were followed for a mean of 6.1 years (range, 3-8 years). Mean Harris hip score improved from 58 points preoperatively to 91 points postoperatively. There were no cases of PE liner dislodgement or progressive osteolysis. 1 hip (2.8%) required revision surgery for acetabular cup loosening with greater trochanteric fracture. Complications included 1 peroneal nerve palsy and 1 dislocation. The results of this study and previous reports demonstrated that cementation of highly cross-linked PE liner into well-fixed metal shell could provide good midterm durability.

Extensively Porous-coated Stems for Femoral Revision: Reliable Choice for Stem Revision in Paprosky Femoral Type III Defects

Between January 1999 and August 2008, ninety-six femoral revisions were performed with extensively porous-coated stems in Paprosky type III femoral defects (89 type IIIA and 7 type IIIB defects). Seven type IIIB defects with a mean canal of 16.5 mm were observed; 6 defects achieved stable bone ingrowth and 1 achieved stable fibrous condition. Average postoperative Harris Hip Score was 92.3±8 (range, 77-100), and all scores improved postoperatively. At a mean follow-up of 65.7 months, 92 stems achieved bone ingrowth, and 1 stem (type IIIB) achieved a stable fibrous condition. Three patients died from causes unrelated to the surgery during follow-up. The most frequent diagnosis for revision of the femoral component was loosening of the cementless stem (53 patients; 55.2%), followed by status after a Girdlestone procedure (21 patients; 21.8%), after total hip arthroplasty with acetabular wear (10 patients; 10.4%), loosening of the cemented stem (7 patients; 7.3%), and periprosthetic fracture (5 patients; 5.2%). The authors performed 65 total hip arthroplasty revisions, 23 femoral component revisions, and 8 revisions of femoral components with cemented liners in patients with well-fixed acetabular shells. Extensively porous-coated stems in femoral revision for Paprosky type III femoral defects provided good mid-term durability.

Cementing Polyethylene Liners into Non-Modular Acetabular Components in Revision Total Hip Arthroplasty

To review mid-term results after replacing the polyethylene liner in a well-fixed acetabular shell. 22 patients underwent replacement of the polyethylene liner in a well-fixed acetabular shell using cementation. The inner surface of the metal shell was scored with grooves (1 to 2 mm deep) for cement interdigitation. Trial liners were used to assess the appropriate size, with an aim to provide at least 2 mm of an even cement mantle behind the polyethylene liner. None of the liners were constrained or lipped. Clinical and radiographic outcomes were evaluated, and Harris Hip Scores obtained. Radiographic loosening of the acetabular shell was recorded. Implant survival was evaluated using the Kaplan- Meier estimator. After a mean follow-up of 70 (range, 21-189) months, 17 patients had stable hips and their mean Harris Hip Score was 89 (range, 72-93). Four patients underwent re-revision after 28 to 108 months for aseptic loosening of the acetabular shell (n=2) and recurrent dislocation (n=2). One patient showed radiographic evidence of acetabular migration but was stable. The femoral components of all patients were stable. 92% of patients had good-to-excellent results. Implant survival at 60 months was 81% (95% confidence interval [CI], 51-94%); it became 91% (95% CI, 61-99%) if reductions for dislocations were excluded. Cementation of an undersized polyethylene liner into a non-modular shell is one option for revision of a well-fixed acetabular shells. Nonetheless, further follow-up is required to determine if it remains a viable option in the long term. If there is any doubt about the stability of the acetabular shell, a complete revision should be performed.

Results of Selective Hip Arthroplasty Revision in Isolated Acetabular Failure

Controversy exists over whether to remove well-fixed components at the time of revision of a failed total hip arthroplasty (THA). The purpose of this study was to evaluate the results of selective acetabular revision after acetabular failure in which only the failed component was replaced. Thirty-six isolated acetabular component revisions were performed and prospectively followed for a mean of 4.7 y (range, 2-9.3 y). The components had been in place for a mean of 10.8 y. All femoral components and some metal-backed acetabular shells were well fixed at the time of revision and left in place. Surgery involved cementation of an acetabular liner into a well-fixed acetabular shell in 16 cases, and acetabular revision in 20 cases. Morselized cancellous allograft was used to fill acetabular defects in 27 hips, and proximal femoral defects in 17 hips. Bulk allografts were used to reconstruct the proximal femur in two hips. The mean Harris hip score improved from 57.8 preoperatively to 89.1 at the final follow-up visit. The results were rated excellent in 24 patients, good in nine patients, and fair in three patients. The unrevised femoral components and acetabular shells remained well fixed, and final follow-up radiographs revealed no cases of osteolytic lesion progression around the femoral and acetabular components. Revision of only the failed acetabular component is recommended in cases of isolated acetabular failure, providing excellent results over the medium term, and allowing preservation of bone stock with lower surgical morbidity.

Primary Total Hip Arthroplasty with a Porous-Coated Acetabular Component

We previously reported the seven and fifteen-year results of the use of a porous-coated acetabular metal shell inserted without cement in a consecutive series of 204 primary total hip arthroplasties. In the present study, we evaluated the longer-term outcomes of these arthroplasties at a minimum follow-up time of twenty years. One hundred and fourteen (92%) of the 124 hips available for study had retained the original acetabular metal shell. A total of five acetabular components had been revised for aseptic loosening or had radiographic evidence of definite loosening. Fourteen hips with well-fixed acetabular shells required a change of the modular acetabular liner because of excessive wear and/or for the treatment of osteolysis, and liner changes have been recommended for another eight hips. The twenty-year rate of survival of the metal shell, with failure defined as revision because of loosening or radiographic evidence of loosening, was 96% (95% confidence interval, 94% to 98%). Cementless acetabular reconstruction continues to provide durable fixation at twenty years postoperatively. Wear-related complications continue to be the major mode of failure.

Cementation of a Polyethylene Liner Into a Metal Acetabular Shell: A Biomechanical Study

Cementation of a liner into a well-fixed acetabular shell is common in revision hip arthroplasty. We compare the biomechanical strengths of cemented liners with standard locked liners. Fifty polyethylene liners were inserted into acetabular shells using the standard locking mechanism or 1 of 2 cement types then loaded to failure by torsion or lever-out testing. Lever-out testing showed that all cemented liners failed at similar loads to standard locked liners. With torsion testing, cemented liners failed at significantly higher loads than standard locked liners; roughening the liner increased load to failure. Cementation of an acetabular liner into a metal shell is safe and strong and a good alternative to metal shell replacement. Saw roughening of the polyethylene liner strengthens the poly-cement interface.

Revision of an acetabular liner has a high risk of dislocation

Polyethylene liners of modular acetabular components wear sometimes need to be replaced, despite the metal shell being well fixed. Replacing the liner is a relatively simple procedure, but very little is known of the outcome of revision. We prospectively followed up 1126 Harris-Galante I metal-backed, uncemented components for between nine and 19 years. We found 38 (3.4%) liners of 1126 acetabular components wore and required revision. These revisions were then followed up for a mean of 4.8 years. The rate of dislocation was 28.9%. Nine of the dislocations occurred once and two were recurrent. The overall secondary revision rate was three of 38 total hip replacements (7.9%) at a mean follow-up of 4.8 years. This gives a 92.1% survivorship (35 of 38) at under five years. In isolated revision of a liner, we had a complication rate of 23% (three of 13). In revision of a liner combined with revision of the femoral stem, there was a complication rate of 48% (12 of 25). We discuss possible reasons for the high dislocation rates. Leaving the well-fixed acetabular shell in situ leads to an increased risk of instability. However, this needs to be balanced against the otherwise low complication rate for revision of the liner. Patients should be consented accordingly.

Cementing a liner into a stable cementless acetabular shell: the double-socket technique.

During revision hip replacement surgery, the cementless acetabular shell is often well fixed but the locking mechanism may be ineffective. Cementing a new liner into the existing acetabular shell (the double-socket technique) can provide a simple solution. The purposes of the present study were to review our initial clinical results and to define the potential limitations of this technique. Thirty-two hips with a preexisting well-fixed acetabular socket that had been in situ for an average of 8.6 years were treated with the insertion of a new polyethylene liner (seventeen hips) or a metal liner (fifteen hips) with use of cement. The indication for this technique was a deficient locking mechanism in twenty-two hips and the unavailability of a matching liner in ten hips. Anteroposterior radiographs of all hips were analyzed by a single independent reviewer. The mean duration of follow-up was 5.1 years. Six hips required a reoperation after a mean of 29.7 months; the reasons for the reoperations included aseptic failure of the acetabular construct (four hips), instability (one hip), and sepsis (one hip). The University of California at Los Angeles hip scores improved significantly (p < 0.001) compared with the preoperative values; specifically, the mean score improved from 6.2 to 9.1 for pain, from 6.3 to 8.3 for walking, from 6.2 to 7.8 for function, and from 4.7 to 5.8 for activity. The prevalence of dislocation was 22%. Kaplan-Meier analysis with revision as the end point revealed a five-year survival rate of 78% (95% confidence interval, 55% to 91%). The double-socket technique is a good alternative to acetabular socket removal for suitable candidates who have a well-fixed cementless socket with an inner diameter that is larger than the outer diameter of the cemented liner. This technique preserves acetabular bone stock and permits conversion to alternate bearing surfaces. We believe, however, that removal of a well-fixed acetabular shell or the use of a constrained liner should be strongly considered for patients with a history of hip instability.

Cementation of an acetabular liner into a well-fixed acetabular shell during revision total hip arthroplasty

Cementing a polyethylene liner into a well-fixed acetabular shell during revision hip arthroplasty may be appropriate in select patients. The purpose of this study was to review our early results with this technique. Sixteen patients with >2-year follow-up or who had any complications at <2 years from surgery were identified. Indications for this technique included: failure of the previous locking mechanism, significant polyethylene wear, malposition of the well-fixed metal shell, and previous removal of the liner with a retained acetabular shell. One acetabular shell has been revised at 13 months for multiple dislocations. Hip scores improved an average of 24.2 points. Radiographs revealed no polyethylene dissociation or acetabular loosening. Complications occurred in 7 patients. Initial results appear successful at providing secure fixation, while preventing the bone loss that might occur with removal of a well-fixed component.