Cementation of a polyethylene liner into a metal shell. Factors related to mechanical stability

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

Aims

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.

Methods

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.

Results

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).

Conclusion

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.

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

BACKGROUND

Cementing 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.

METHODS

This 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).

RESULTS

The 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.

CONCLUSION

Cementing 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.

Isolated Liner Exchange in Total Hip Arthroplasty at a Mean of 13 Years of Follow-up: Does Fixation Technique Matter?

BACKGROUND

Isolated liner exchange is an option to address polyethylene wear after total hip arthroplasty (THA). The liner can be fixed with either the original locking mechanism or cemented into the acetabular cup. Whether the method used for liner fixation has any bearing on the outcomes in the first and second decade after surgery is still unclear.

METHODS

Data for all patients who had undergone isolated liner exchange surgery in our institution between April 1995 and January 2015 were retrieved. Patients were classified according to the type of polyethylene liner (conventional or highly crosslinked polyethylene) and the locking mechanism used (original locking mechanism or cemented). Survivorship and revision rates were compared among different subgroups. A total of 118 isolated liner exchanges were performed and patients had a mean duration of follow-up of 13 years (range, 5 to 25).

RESULTS

Overall estimated mean survivorship was 17 years. Use of highly crosslinked polyethylene (HXLPE) had a lower re-revision rate compared to conventional liners (10.5 versus 46.9%) (P < .001). The re-revision rate of exchanges using HXLPE was not affected by the type of fixation (original locking mechanism 11.1 versus cement 10.0%, P = .868). Conversely, using the original locking mechanism with a conventional liner had a higher re-revision rate compared to cemented conventional liners (58.3 versus 12.5%) (P = .024).

CONCLUSION

HXLPE liners should be used in insert exchange surgery whenever possible. Re-revision rate of exchanges using HXLPE was not affected by the fixation technique used. Cementing an insert into an acetabular component is associated with good survivorship at a mean of 13 years follow-up.

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

BACKGROUND

The "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.

METHODS

From 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.

RESULTS

The 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.

CONCLUSIONS

We 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.

Cementation of a Dual Mobility Cup Into an Existing Well-Fixed Metal Shell: A Reliable Option to Manage Wear-Related Recurrent Dislocation in Patients With High Surgical Risk

BACKGROUND

During revision total hip arthroplasty (THA), the "double-socket" technique has been proposed as a straightforward solution in order to reduce the overall perioperative morbidity in patients with high surgical risk. However, the option of cementing a dual mobility cup into an existing well-fixed metal shell was sparsely reported. Therefore, this study aimed to evaluate the outcome of a "double-socket" technique performed with a cemented dual mobility cup in revision THA for late instability.

METHODS

Twenty-eight revision THAs (28 patients) were performed for wear-related recurrent dislocation using a "double-socket" technique with a cemented dual mobility cup and retrospectively reviewed. The age at revision averaged 82 years (range 74-93). According to the American Society of Anesthesiologists (ASA) physical status classification, 12 patients (43%) were ASA II and 16 patients (57%) were ASA III before revision.

RESULTS

At a mean follow-up of 3.5 years (range 2-5), the mean preoperative to postoperative functional outcome improved significantly (P < .01). The mean operative time was 107 minutes (range 75-140). The mean intraoperative bleeding was 200 mL (range 110-420). No postoperative complication, reoperation, or re-revision was reported. Importantly, no dislocation, dissociation of the cemented dual mobility cup construct, or aseptic loosening of the retained metal shell was observed.

CONCLUSION

The "double-socket" technique with a dual mobility cup cemented into an existing well-fixed and well-positioned metal shell ensured a straightforward and blood-sparing revision technique that was efficient to restore stability and provide a secure acetabular construct in frail patients with high surgical risk and/or older than their natural life expectancy.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

LEVEL OF EVIDENCE

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

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

LEVEL OF EVIDENCE

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

Using Double-Contrast CT Arthrography to Confirm Suspected Dissociation of a Cemented Polyethylene Liner in the Setting of Revision Total Hip Arthroplasty: A Case Report

CASE

A 67-year-old woman who underwent a re-revision of a total hip arthroplasty with a cemented polyethylene liner fell 14 months after surgery. The patient had symptoms of pain and weakness; however, clinical, laboratory, and radiographic evaluation did not disclose fracture, infection, osteolysis, or component migration. Liner dissociation was suspected, and a double-contrast computed tomography (CT) arthrogram confirmed failure at the cement-liner interface. She underwent additional revision surgery and was doing well at the 3-year follow-up.

CONCLUSION

Double-contrast CT arthrography confirmed failure at the cement-liner interface and is an effective diagnostic tool in identifying suspected dissociations of cemented polyethylene liners.

Cementing Constrained Liners Into Secure Cementless Shells: A Minimum 15-Year Follow-Up Study

BACKGROUND

The authors and others have previously described the technique of cementing constrained liners into secure cementless acetabular shells and reported the short-term, average 3.9-year follow-up, using that technique. The purpose of the present study was to report the minimum 15-year follow-up of this same cohort.

METHODS

Between 1988 and 2000, 31 consecutive constrained liners of one design were cemented into well-fixed, well-positioned cementless acetabular shells at 3 institutions. Average age at surgery was 72 years (range, 31-91 years). Indications for the procedure were recurrent hip dislocation in 16 cases and intraoperative instability in 15 cases. Patients were evaluated for revision for failure of the device and revision for any reason.

RESULTS

At minimum 15-year follow-up, there was 1 patient lost to follow-up. Three hips (9.7%) were revised for failure of the device and 5 hips (16.1%) were revised for any reason.

CONCLUSION

At minimum 15-year follow-up, considering the complexity of cases, there was excellent medium-term durability of this construct.

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

INTRODUCTION

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.

METHODS

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.

RESULTS

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).

DISCUSSION

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.

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

BACKGROUND

Acetabular 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.

METHODS

Twenty-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.

RESULTS

When 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).

CONCLUSION

Biomechanical 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.

Long-Term Outcomes of Liner Cementation into a Stable Retained Shell: A Concise Follow-up of a Previous Report

Liner cementation into a preexisting stable socket may reduce the morbidity of revision hip arthroplasty and preserve acetabular bone. However, the long-term outcomes of this technique remain unknown. The purpose of this report was to analyze the long-term results of a previously reported cohort of patients. Cementation of thirty-two liners (seventeen polyethylene and fifteen metal liners) into preexisting sockets was performed during revision hip arthroplasty, and the patients were followed for a minimum of two years. A retrospective chart review was performed to investigate the complications and survivorship. The mean duration of follow-up was 12.7 years (range, 2.1 to 19.1 years), with ten hips requiring rerevision at a mean of 6.4 years (range, 1.0 to 15.5 years). Nine patients experienced posterior dislocations, and two hips required rerevision for instability. Liner dissociation from the shell occurred in two patients. Survivorship analysis, with rerevision as the end point, demonstrated ten and fifteen-year survivorship of 77.3% and 68.8%, respectively. Dissociation of the cemented liner from the acetabular shell was an infrequent cause of failure despite long-term follow-up. Given the high rate of dislocations in this study, careful patient selection and surgical technique should be considered.

LEVEL OF EVIDENCE

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

Long Term Results of Liner Polyethylene Cementation Technique in Revision for Peri-acetabular Osteolysis

Patients with peri-acetabular osteolysis around a well fixed cementless acetabular component may be treated with liner exchange. When the locking mechanism is unreliable or unavailable, cementing the liner into the fixed acetabular component is a feasible option. The purpose of this study was to evaluate the clinical and radiographic long term results of this technique. Forty hip revisions with liner cementation in 37 patients were performed. The minimum follow up was 10 years. Modified Harris Hip Score and recent x rays were reviewed. Four hips were re-revised. Two patients were diagnosed with exacerbation of osteolysis but refused revision. Dislocation rate was relatively high (16%). Liner cementation technique in revision hip surgery is useful in patients with a well fixed metal backed acetabular component.

[Polyethylene replacement by cementing a new component over the osseointegrated metal-back]

OBJECTIVE

In uncemented revision total hip replacement due to polyethylene wear, the metal cup needs to be maintained when its stability is checked during surgery, only replacing the polyethylene that is cemented if anchoring is not possible. The aim of the present study was to evaluate the medium-term clinical and radiological results of a polyethylene liner cemented into an osseointegrated acetabular shell component.

MATERIAL AND METHOD

A retrospective analysis was performed on 15 patients in whom the surgical indication was polyethylene wear, with a mean follow-up of 6.1 years (range 3.5-9.7 years). The Harris Hip Score was used to assess the clinical results before surgery and at the end of follow-up. Anteroposterior and axial X-rays of the hip were taken to rule out complications.

RESULTS

The mean Harris Hip Score improved, increasing from 64.7 points before the surgery to 80.3 at the end of follow-up. The osteolytic lesions disappeared, or at least the size did not increase, in the follow-up X-rays. One patient (6.7%) suffered 2 dislocation episodes that were treated without the need for surgery. Another patient presented with aseptic loosening of the femoral stem that required a replacement.

CONCLUSIONS

Cementing the polyethylene liner, when anchoring is not possible, in an uncemented osseointegrated metal shell is a technique that offers good results in the medium term, and which may minimise the complications that may occur with the replacement of the shell component, without compromising its stability.

Revision Total Hip Arthroplasty with Retained Acetabular Component

BACKGROUND

Aseptic loosening and osteolysis commonly limit the survivorship of total hip prostheses. Retention of a well-fixed acetabular component, rather than full acetabular revision, has multiple advantages, but questions have lingered regarding the clinical success and prosthetic survivorship following this procedure. We examined the impact of acetabular component position, polyethylene type, liner insertion technique, femoral head size, and simultaneous revision of the entire femoral component (as opposed to head and liner exchange) or bone-grafting on mid-term to long-term prosthetic survival following such limited revisions.

METHODS

One hundred hips in 100 patients with osteolysis, polyethylene wear, or femoral component loosening underwent revision total hip arthroplasty with retention of the acetabular component. Acetabular component inclination and anteversion were measured on prerevision radiographs and were categorized according to predetermined positional safe zones (inclination of 35° to 55° and anteversion of 5° to 25°). Operative reports were reviewed for femoral head size, polyethylene liner type (conventional or highly cross-linked), liner insertion technique (use of the existing locking mechanism or cementation), whether the patient had revision of the entire femoral component, and use of bone graft. Outcomes of interest included the Harris hip score, University of California at Los Angeles (UCLA) activity score, episodes of instability, and need for repeat revision.

RESULTS

At an average of 6.6 years (range, two to fourteen years) postoperatively, the Harris hip and UCLA activity scores were both significantly improved compared with the preoperative scores (p < 0.0001 and p < 0.01, respectively). Overall, the failure rate was 13%. In addition, 6% of the patients had postoperative instability. Hips in which the acetabular component was outside of the safe zone for inclination had a higher rate of failure (p = 0.048). Use of conventional, rather than highly cross-linked, polyethylene at the time of revision was also associated with an increased rate of repeat revision (p = 0.025).

CONCLUSIONS

Revision total hip arthroplasty with retention of the acetabular component is associated with good outcomes in hips with an appropriately positioned, well-fixed acetabular component. Acetabular components outside the safe zone for inclination were at a higher risk for failure, as was use of conventional polyethylene.

LEVEL OF EVIDENCE

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

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.

Cementation of a dual-mobility acetabular component into a well-fixed metal shell during revision total hip arthroplasty: a biomechanical validation

Cementation of polyethylene (PE) liners into well-fixed metal shells has become a popular option during revision total hip arthroplasty (THA) particularly for older and frail patients. Although dramatic results were reported with dual-mobility acetabular components to manage hip instability during revision THA, no study evaluated the fixation strength of the cementation of dual-mobility components into well-fixed metal shells. Eight dual-mobility and eight all-PE components were cemented into a metal shell with a uniform 2- to 3-mm cement mantle. The cemented fixation strength was evaluated using lever-out and torsion testing. The interface at which failure occurred was determined. Lever-out testing showed that dual-mobility components failed at significantly higher maximum moment than the all-PE components. No direct comparison could be performed with torsion testing due to early failure of the all-PE component itself before failure of the cement fixation. However, the maximum moments measured were dramatically higher than the in vivo frictional moments classically reported in THA. In addition, failure was always observed at the metal shell/cement interface whenever it did occur. In conclusion, a dual-mobility acetabular component cemented into a well-fixed metal shell could constitute a biomechanically acceptable alternative to acetabular shell removal or PE liner cementation while simultaneously preventing instability of the THA revision. Clinical studies are warranted.

Dual-mobility bearings: a review of the literature

Dislocation after total hip arthroplasty remains a major problem and hip instability is the most common reason for revision. These complications are costly to both patients and the healthcare system, and efforts to reduce them have had varied degrees of success. Although there are well documented patient and surgical risk factors for dislocation, the typical surgical solutions offered (constrained liners, large femoral heads) have the drawbacks of reduced range-of-motion and high rates of revision. Dual-mobility prostheses (unconstrained tripolar prostheses) are hip design solutions to dislocation that aim to provide a greater stability with an increased range-of-motion, along with potentially reduced wear. The mean overall dislocation rate from multiple combined studies using dual-mobility prostheses was 0.1% for primary total hip arthroplasty and 3.5% for revisions, compared with 2-7% for standard primary total hip arthroplasties and up to 16% for revisions. Dual-mobility prostheses offer a viable option for treating recurrent dislocation as well as for primary and revision arthroplasty.

Acetabular liner revision using an anterolateral approach

Total hip arthroplasty (THA) is recognized as a successful treatment for degenerative hip joint disease. An epidemiological study using the National Hospital Discharge Survey in the United States reported that the number of primary THAs increased from 119,000 in 1990 to 193,000 in 2002. According to nationwide inpatient sample data, the demand for primary THA was estimated to increase from 208,600 in 2005 to 572,000 (174%) in 2030 in the United States. The number of revision THAs in the United States has subsequently increased and is projected to increase from 40,800 in 2005 to 96,700 in 2030. Because revision THAs have a higher incidence of dislocation than primary THAs, preserving the soft tissue, including the gluteus medius muscle, is more necessary at revision THA. However, to our knowledge, few studies have reported soft tissue damage at revision THA. An anterolateral modified Watson-Jones approach, which is between the hip abductor and the tensor fascia lata, preserves the abductor muscles.This article describes 2 cases in which acetabular liner revision was performed through an anterolateral modified Watson-Jones approach. The anterolateral approach provided an excellent surgical field at acetabular liner revision, with no major complications, and has the possibility of being a useful for acetabular liner revision.

Cementation of tibial inserts into nonmatching base plates in revision total knee arthroplasty

We describe the use of a novel technique for adapting nonmatching tibial inserts into tibial trays in revision total knee arthroplasty. From 1998 to 2003, the senior author performed 7 revision total knee arthroplasty procedures, during which a nonmatching tibial insert was cemented into a tibial tray to retain a well-fixed but incompatible opposite component. Bench tests were undertaken to confirm the stability of cement as a locking mechanism substitute. Three components completed 1 000 000 cycles of loading under simulated physiologic stresses with no evidence of fixation failure. There have been no clinical failures at 18 to 69 months in vivo follow-up (mean, 49 months). This technique provided durable fixation while avoiding host bone damage that might have occurred needlessly had the well-fixed implant been extracted.

LEVEL OF EVIDENCE

level IV therapeutic study, case series.

Failure of cement-in-shell acetabular liner exchange

Cement-in-shell acetabular liner exchange is a revision surgery option for cases of total hip arthroplasty (THA) with polyethylene wear where direct liner exchange is not possible. A replacement liner is cemented into a well fixed uncemented acetabular shell, avoiding the morbidity associated with acetabular shell component revision. We present a case of dissociation of an acetabular liner at the cement-liner interface, three years following liner exchange without radiographic evidence to indicate the diagnosis.

Cementing polyethylene liners into non-modular acetabular components in revision total hip arthroplasty

PURPOSE

To review mid-term results after replacing the polyethylene liner in a well-fixed acetabular shell.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Cementation of cross-linked polyethylene liner into well-fixed acetabular shells: mean 6-year follow-up study

The purpose of this study was to evaluate retrospectively the outcomes of cementation of cross-linked polyethylene (PE) liner in a well-fixed metal shell in 23 hips with an average follow-up period of 6 years. The mean Harris hip score was 69.6 +/- 12 (range, 46-83) points preoperatively. The average postoperative follow-up was 72.3 months (range, 56-100 months). At the final follow-up, the mean Harris hip score was 95.5 +/- 3 (84-100) points. There was no change in the bone-shell interface. No new osteolytic lesions were identified. The lesions impacted with bone graft had united completely. The remaining osteolytic lesions had decreased in size. There was no recurrent osteolysis, hip dislocation, component migration, and failure at the cement-metal interface. The results of the current study revealed that cementation of cross-linked PE liner into a well-fixed shell provided good midterm durability.

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.

Polyethylene liner cementation technique in asymptomatic versus symptomatic osteolysis

Osteolysis around a cementless acetabular component can lead to severe bone loss. This study examined whether osteolysis should be treated while still asymptomatic. Thirty-seven liner cementation revisions were performed in 34 patients. Mean patient age was 61 years, and mean time elapsed after index surgery was 85 months (range, 36-168 months). Patients were evaluated by Harris Hip Score (HHS), and mean follow-up was 5 years (range, 43-82 months). Average HHS was 87 with a pain component of 39. In asymptomatic patients, both the HHS and the pain score were significantly higher: 95 and 43, respectively (P<.01). One patient with extensive bone loss had a fracture of the acetabulum and underwent revision at another institution. Revision of the polyethylene liner and cementation of a new one is a useful technique in patients with a stable acetabular shell. This is especially true for asymptomatic patients with osteolysis and thus should be performed early; however, high dislocation rate is still a concern.

Cement as a locking mechanism for screw heads in acetabular revision shells - a biomechanical analysis

In acetabular revisions, polyethylene (PE) liners are often cemented into metal shells on top of acetabular screw heads. This study investigates the possibility of using this technique to obtain fixed-angle acetabular screws Eth a concept that has not yet been reported in the literature. Two groups of screws (n=8) were inserted into Trabecular Metal revision shells (Zimmer), into which PE liners were then cemented. Screws in Group 1, inserted in the shell's pre-fabricated holes, were countersunk, whereas screws in Group 2 were inserted in custom-drilled holes that make their heads protrude into, and interdigitate with, the overlying cement mantle. Perpendicular loading was then applied to the screw shafts both statically to failure and cyclically. A greater stiffness was observed for the protruding screws upon static loading; and while the countersunk screws all failed at the screw-cement junction (53.44 + or - 8.33 N), the protruding screws all failed at the screw shaft (1049.79 + or - 32.12 N) a 20-fold difference (p< 0.05). Under cyclic loading, only the protruding screw head specimen did not fail, undergoing an overall displacement within the limits of osseointegration.These results support the hypothesis that the protrusion of an acetabular screw head into an overlying cement mantle significantly increases its angular stability. Provided other variables are favorable, this locking effect may increase the initial stability of the whole implant, thus improving the ultimate success of complex acetabular revisions.

Cementation of polyethylene liners into well-fixed metal shells at the time of revision total hip arthroplasty

Cementing polyethylene liners into well-fixed metal shells at revision total hip arthroplasty is an accepted technique. Previous studies have tested the initial strength of this construct, but none have tested the construct under physiologic and abnormal loading conditions. The current study examines liner-shell performance under these conditions. In addition, this study quantitates whether hand-modified regular liners or liners designed for cementation with integrated cement spacers, which provide an even cement mantle, perform better. Cyclic loads of up to 4000 N for 500,000 cycles followed by 2000 N for 200,000 cycles of edge loading were used. The liners with integrated spacers demonstrated higher lever-out moments and statistically significant increase in tear-out loads.

Failure of constrained acetabular liner without metal ring disruption

Constrained acetabular liners can fail leading to recurrent dislocation. Failure can occur at any of the five possible interfaces: bone-acetabular shell, acetabular shell-constrained liner insert, constrained liner insert-bipolar head, bipolar head- femoral head and femoral head-trunion. We report a patient who presented with dissociation of the cemented Osteonics acetabular constrained liner (Stryker-Howmedica-Osteonics, Rutherford, New Jersey). The failure interface was at the factory pre-assembled constrained liner insert-bipolar head without any locking ring failure; instead there was deformation of the constrained liner insert's polyethylene rim, which facilitated dissociation. To our knowledge, there are no previous reports of such a failure mode pertaining to this type of constrained liner. Constrained acetabular liners are indicated during primary or revision total hip arthroplasty for patients who are at high risk for dislocations or who have had recurrent dislocations. Failure rates (typically recurrent dislocation) range from 4% to 29% at mid-term follow-up. The first report on the Osteonics acetabular constrained liner was published in 1994. Failures have been reported previously to occur at surgically controllable interfaces, such as the acetabular shell from the bony surface and the constrained liner insert from the acetabular metal shell, and have been attributable to excessive constraint or improper technique. All dissociations pertaining to factory-preassembled component interfaces have been attributed to breakage of the locking ring. This article presents the first case of disengagement of the tripolar constrained liner without disruption of the locking ring.

[Polyethylene liner replacement: behavior and morbidity in 68 cases]

PURPOSE OF THE STUDY

Isolated acetabular polyethylene exchange is advocated as an advantage of metal-backed cups, since the acetabular bone stock can be spared and operative time is shorter. The purpose of this study was to determine whether this is true.

MATERIAL AND METHODS

A consecutive serie of 68 THA revisions involving replacement of the polyethylene liner was analyzed retrospectively (liner replacement alone for 37 hips and liner replacement plus femoral component revision for 31). The posterolateral approach was used for the revision in all cases. This series was compared with a control series of revisions involving the acetabular component with revision of the femoral component in patients matched for age, sex, and BMI.

RESULTS

Operative time and hospital stay were significantly shorter when the revision involved the polyethylene liner alone. In 19 hips, a limited zone of osteolysis was observed around the liner before replacement. At last follow-up, new zones of osteolysis were noted in two hips and aggravation in five, one of which required revision because of acetabular loosening. Episodes of dislocation were observed in nine hips (2 anterior and 7 posterior) of which three underwent revision because of recurrence. These dislocations occurred after liner replacement (n=4) or combined liner and femoral component replacement (n=5). Dislocations were more frequent after multiple hip operations and when the cup inclination was less than 40 degrees . Ten revisions were required for: an unclipped liner (n=2), recurrent dislocation (n=3), acetabular loosening (n=1), infection which was cured after a one-stage procedure (n=1). At seven years, survival was comparable between liner replacement alone (82+/-10%), combined liner replacement and femoral component revision (84+/-11%), and femoral component and acetabular component revision (82+/-11%).

DISCUSSION

Changing the cup liner can limit morbidity compared with a more complex revision, but liner replacement alone is insufficient in the event of acetabular osteolysis. It would be preferable to combine osteolysis debridement with a graft or a complete revision. The survival rate after liner replacement is comparable with that observed after more complex revision but the risks of dislocation or unclipped insert are significant. For this reason, liner replacement alone should only be proposed if the cup is correctly aligned and if the new liner can be solidly clipped into the metal back. In addition, this simplified procedure should not be attempted after multiple hip operations.

Cementation of a polyethylene liner into a metal shell

As the number of revision hip arthroplasties continues to increase, alternative reconstructive options may be necessary. Cementation of a polyethylene liner into a well-fixed metal acetabular shell has previously been reported to save bone stock and enhance the pullout strength. This study analyzed whether cementation of various types of mechanically modified or nonmodified liners into a metal shell altered wear characteristics when compared with noncemented modular liners. The authors used nonirradiated and highly cross-linked polyethylene liners that were mechanically modified or left unmodified. Wear in both nonirradiated and highly cross-linked liners was not affected by the cementing process. Wear of the highly cross-linked polyethylene liners was significantly less when compared with the nonirradiated liners. This laboratory study provides quantitative data supporting previous qualitative studies of cementing a polyethylene liner into a metal-backed acetabular shell. Based on this study, cementation of a mechanically modified liner did not affect wear in this study, which simulated 3 years of activity.

Revision of the polyethylene component for wear in TKA

Given reports of failure in isolated polyethylene exchange in well-fixed TKA components, we asked whether isolated exchange could be successful either by replacing the polyethylene in implants whose locking mechanism accepts currently available polyethylene designs or by creating a new locking mechanism fabricated with a carbide bit and augmented with polymethylmethacrylate cement. We performed isolated liner exchange for wear in 46 patients (49 knees). The polyethylene locking mechanism in two total knee designs (13 knees) allowed polyethylene exchange without polymethylmethacrylate fixation. A locking mechanism was fabricated for three implant designs (36 knees). Clinical function after polyethylene component exchange was good in all but three knees. No knees with a fabricated locking mechanism failed. The mechanical strength of the fabricated locking mechanism was tested in the laboratory. The cement- fabricated locking mechanism in the unmodified tray notably outperformed the standard polyethylene locking mechanism. Isolated polyethylene component exchange was successful in this small clinical study. Fabricating a locking mechanism with a carbide bit and acrylic cement was effective in laboratory testing and clinical application.

Isolated liner exchange using the anterolateral approach is associated with a low risk of dislocation

Authors of reports on the outcome of isolated liner exchange for osteolysis and wear have reported high dislocation rates. Twenty-six patients (27 hips) with a minimum of 2 years of followup had isolated liner exchange for wear and osteolysis done using the abductor splitting anterolateral approach. The mean followup was 41 months. The average age at time of surgery was 51 years. Preoperative Harris hip scores averaged 70, and increased to 82 at the most recent followup. We observed improvements in pain and functional scores. The average operating time was 82 minutes, and the average blood loss was 255 mL. Only three (12%) patients required transfusion. No components were rerevised for aseptic loosening, and one patient (one hip) had a dislocation (3.7%). Isolated liner exchange for osteolysis and wear done using the anterolateral approach has a lower risk of dislocation than previously reported and provides substantial improvements in pain, function, and Harris hip score.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Cementation of a metal-inlay polyethylene liner into a stable metal shell in revision total hip arthroplasty

The purpose of this study was to evaluate the results of liner cementation into a stable acetabular shell using a metal-inlay polyethylene liner in 39 revision total hip arthroplasties. After an average of 2.8 years, 1 cemented liner dislodged from its metal shell at a postoperative 4 years. In the other 38 hips, mean Harris hip scores improved from 65 preoperatively to 86.9 at the final follow-up. Eighteen patients were rated as having excellent results, 17 as good, and 3 as fair. There were no changes in cup position and no cases of osteolytic lesion progression around the femoral and acetabular components in the last follow-up radiographs. Metal-inlay polyethylene liner cementation into a stable acetabular shell was found to provide an alternative option with short-term excellent results, and it also offers more liner options, the preservation of bone stock, and lower surgical morbidity.

Constrained acetabular liners: mechanisms of failure

Although constrained acetabular liners have been successfully used for the treatment of recurrent hip instability, their usage has led to a growing number of associated complications. Twenty-seven patients (29 hips) who experienced failure of the constrained acetabular construct were retrospectively reviewed to define mechanisms of failure. Of these patients, 8 had a recurrent failure of another constrained liner. The 4 modes of failure were failure of fixation to the pelvis, liner dissociation, biomaterial failure, and femoral head dislocation. As constrained liners are highly subject to mechanical overload, the risk of failure can be minimized by reducing prosthetic impingement and avoiding technical errors.

Use of constrained acetabular liners in total hip arthroplasty

The use of constrained acetabular liners is indicated when soft-tissue tensioning techniques such as femoral neck lengthening, component repositioning, and use of lateralized acetabular liner are ineffective. It is most commonly used as a salvage procedure in revision situations. However, a locking acetabular insert may be used for primary THAs in patients with joint or soft-tissue laxity, neuromuscular disease, or intraoperative instability. In addition to the described commercially available liners, several manufacturers will provide customized components on request.

Fixation strength of an all-metal acetabular component cemented into an acetabular shell: a biomechanical analysis

When an acetabular shell is well fixed but the locking mechanism is compromised, cementing a new liner into the existing acetabular component can provide a simple revision solution. The pull-out and torsional fixation strength of cobalt chromium (CoCr) alloy acetabular components cemented into 3 sizes of titanium alloy acetabular components was tested under conditions of 0 or 2 mm cement mantle at the dome and 2 mm cement with the cemented component in 20 degrees of version with respect to the shell. The lowest mean tensile load to failure was 1500 N, and occurred with no cement at the dome of the 54 mm shell, whereas the greatest load was with 2 mm cement thickness. Smallest mean torque to failure was 43 Nm. Version angle did not substantially change failure load. Although not cyclically loaded, fixation strength of metal liners cemented into shells was comparable to that of commonly used locking mechanisms, suggesting sufficient strength for clinical application.

Use of a constrained tripolar acetabular liner to treat intraoperative instability and postoperative dislocation after total hip arthroplasty: a review of our experience

Constrained acetabular components have been used to treat certain cases of intraoperative instability and postoperative dislocation after total hip arthroplasty. We report our experience with a tripolar constrained component used in these situations since 1988. The outcomes of the cases where this component was used were analyzed for component failure, component loosening, and osteolysis. At average 10-year followup, for cases treated for intraoperative instability (2 cases) or postoperative dislocation (4 cases), the component failure rate was 6% (6 of 101 hips in 5 patients). For cases where the constrained liner was cemented into a fixed cementless acetabular shell, the failure rate was 7% (2 of 31 hips in 2 patients) at 3.9-year average followup. Use of a constrained liner was not associated with an increased osteolysis or aseptic loosening rate. This tripolar constrained acetabular liner provided total hip arthroplasty construct stability in most cases in which it was used for intraoperative instability or postoperative dislocation.

A constrained liner cemented into a secure cementless acetabular shell

BACKGROUND

Constrained acetabular components have been used to treat hips with recurrent instability following total hip arthroplasty and hips that demonstrate instability during revision surgery. In such hips, when a secure cementless acetabular shell is present, the surgeon can cement a constrained liner into the existing shell. The purpose of this study was to evaluate the clinical and radiographic outcome of this technique with use of a tripolar constrained liner that was cemented into a well-fixed cementless acetabular shell.

METHODS

Between 1988 and 2000, constrained liners were cemented into thirty-one well-fixed cementless acetabular shells at three centers. The average age of the patients at the time of the index surgery was 72.1 years, and the indications for the procedure were recurrent hip instability in sixteen hips and intraoperative instability in fifteen hips. The patients were evaluated with respect to the clinical outcome and radiographic evidence of shell loosening and osteolysis.

RESULTS

At an average duration of follow-up of 3.9 years, twenty-nine liners (94%) were securely fixed in the cementless shells and two constrained liners had failed. One liner failed because it separated from the cement, and one failed because of fracture of the capturing mechanism. Both hips were successfully revised with another cemented tripolar constrained liner. No acetabular component demonstrated radiographic evidence of progressive loosening or osteolysis.

CONCLUSIONS

A constrained tripolar liner cemented into a secure, well-positioned cementless acetabular shell provides stability and durability at short-term follow-up. Careful attention to the preparation of the liner, the sizing of the component, and the cementing technique are likely to reduce the failure of this construct, which can be used for difficult cases of total hip instability.

Isolated liner exchange in revision total hip arthroplasty: clinical results using the direct lateral surgical approach

Twenty-four hips (23 patients) underwent isolated polyethylene liner exchange (modular and nonmodular liners) via the direct lateral surgical approach for a preoperative diagnosis of polyethylene wear and acetabular osteolysis. Accessible osteolytic lesions were bone grafted with cancellous allograft. Patients were followed up clinically and radiographically, with a mean follow-up time of 36 months (range, 12-100 months). A computer-assisted method measured lesional area from the radiographs of the 18 hips that presented with osteolysis. Seventeen of 18 lesions either regressed or resolved since the procedure. Two patients required repeat revisions, and no dislocations were noted. Clinically, both Harris Hip and Western Ontario and McMaster Universities Osteoarthritis Index scores improved postoperatively. In selected patients, isolated liner exchange with or without bone grafting is effective for treating polyethylene wear and associated osteolysis. Dislocation rates with revision may be reduced using a surgical approach that preserves an adequate capsular layer for closure in liner exchange surgery.

Isolated acetabular polyethylene exchange through the anterolateral approach

Isolated exchange of an acetabular liner, in the presence of a well-fixed acetabular component, has become an established method for the management of polyethylene wear. Various experienced adult-reconstruction surgeons have noted a high incidence of instability following isolated liner exchange. We report the results of isolated liner exchange in 35 patients with polyethylene wear and osteolysis (16 patients) or polyethylene wear and instability (19 patients) with a minimum follow-up of 2 years. Isolated liner exchange was performed through an anterolateral approach in all cases. Postoperative dislocation occurred in 2 of the 35 patients (6%), both with polyethylene wear and osteolysis. Isolated liner exchange was successful in addressing instability in all 19 patients who presented with polyethylene wear and dislocation. Isolated acetabular liner exchange performed through an anterolateral approach carries an acceptable dislocation rate.

The role of constrained liners in total hip arthroplasty

Recurrent instability after total hip replacement is a complex problem with extensive literature detailing multiple etiologies and solutions. It has been shown that the success of surgical treatment depends on the identification of the cause. Unfortunately, in certain situations, there may not be an optimal solution for dealing with the cause, or the cause may remain unidentified. In these cases, the success rate of surgical treatment of the unstable total hip replacement is only 40% to 50%. Constrained acetabular liners were developed to address the problem of recurrent instability by holding the femoral head captive within the socket. Before the use of constrained liners, there were no reliable solutions to dislocation arising from inadequate soft tissues, a deficient abductor mechanism, or neuromuscular disorders. We have used a constrained liner for these situations, with poor patient compliance and instability without a clear cause as relative indications for its use. Our experience with attaining joint stability using one type of constrained liner has resulted in a 97.6% success rate (83 of 85 hips) at 4.8 years, surpassing the outcomes achieved by other means. The intermediate followup after implantation of a constrained liner has not shown significant rates of component wear or loosening.

Acetabular liner fixation by cement

Many situations in revision THA require the exchange of a PE liner in the setting of a well-fixed cementless acetabular shell. Unfortunately, a replacement liner is not always available, the locking mechanism of the metal shell may be damaged or incompatible with the desired liner, or the shell is malpositioned. Revision of a well-fixed cementless acetabular shell has been associated with considerable morbidity. This raises several questions: can a new PE liner be fixed in the existing shell using bone cement, and if so, which techniques can improve the end result, and in which patients should they be used? Biomechanical testing of cemented PE liners has shown initial fixation strengths that exceed conventional locking mechanisms. It is not known during what period this initial fixation will fail, but clinical reports with followup of as many as 6 years have shown survival in approximately 90% of cases. These studies have shown the importance of proper patient selection, accurate sizing of the PE liner, careful preparation of the substrate of the liner and the shell, and good cement technique. The potential advantages of this technique are less surgical morbidity, more rapid surgery and patient recovery, the ability to incorporate antibiotics in the cement, and more liner options.

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.