Catastrophic failure of the polyethylene liner of uncemented acetabular components

Highly crosslinked polyethylene liner thickness does not influence survival in primary total hip arthroplasty after mean follow-up of 13 years: a study of 2,565 hips with a single design liner

BACKGROUND

Concerns remain that thinner highly crosslinked polyethylene (HXLPE) liners in modern total hip arthroplasty (THA) may lead to premature liner-related failures or revision. The aim of this study was to evaluate the effect of liner-thickness on survival and revision rates of HXLPE in primary THA after more than 10 years.

METHODS

We retrospectively identified 2,565 primary THA using HXLPE with a mean follow-up of 13 years (range, 11 to 19). Patients were grouped for each millimeter (mm) of polyethylene thickness. Liner thickness varied from 4.9 to 12.7 mm, with one third measuring less than 6 mm. Primary outcomes were reoperation, all-cause revision, and liner-related revision.

RESULTS

The reoperation rate was 7.3%, the all-cause revision rate was 5.6%, and the liner-related revision rate was 0.04%. There was no significant difference in all-cause revision when stratified by liner thickness (P=0.286) and liner thickness was not associated with liner-related revision (n=1). There was a statistically, but not clinically significant difference in mean liner thickness for the cohort that underwent reoperation (7.09 vs 6.89 mm, P=0.01) and all-cause revision (7.16 vs 6.89 mm, P=0.031).

CONCLUSION

In our cohort, liner thickness was not associated with all-cause revision-free survival and there was no clinically significant difference in liner thickness between those patients who did require a reoperation or all-cause revision, and those who did not. There was only 1 liner related failure in the entire cohort. Our results indicate that using thinner HXPE liners to maximize femoral head size in THA is a safe practice that does not lead to increased revision rates or liner failure at a mean 13 years follow-up.

Wear debris in metal-on-metal bearings and modular junctions : What have we learned from the last decades?

Metal-on-metal (MoM) bearing hip arthroplasty saw increasing utilization and peaked in the 1990s and early 2000s. Although the linear and volumetric wear rate for a MoM bearings was lower than its polyethylene counterpart, metal ion particles were found to be approximately 10 × smaller and 500 × higher in quantity compared to polyethylene wear debris. Research into these articulations have demonstrated their relationship to the formation of lymphocyte-mediated adverse local tissue reactions. The work-up for metal particle-associated conditions (metallosis) includes a thorough patient history and physical examination, blood laboratory studies for metal ion concentrations, and advanced imaging studies including magnetic resonance imaging (MRI). The treatment of metallosis and adverse local tissue reactions ranges from close serial observation to extensive debridement and full revision of arthroplasty components, when indicated.

What have we learned from 20 years of using highly crosslinked PE in total hip arthroplasty?

Slightly more than 20 years after its first clinical use, highly cross-linked polyethylene (HXLPE) has been widely adopted. Despite initial concerns about oxidation and lack of fatigue resistance, first generation HXLPE, with 15 years of follow-up and widespread use, continues to provide excellent results, even in a young, active population. Remelted HXLPE might have a lower wear rate than annealed HXLPE and will no doubt have a better resistance to oxidation. Second generation materials, consisting of polyethylene (PE) that is sequentially irradiated then annealed and PE that is infused with antioxidants, also have provided encouraging short- and medium-term results. Data from national joint registers confirm data from clinical trials. Even in more challenging cases (dual mobility, hip resurfacing, revision surgery and thin liners), HXLPE has generated promising results. However, failures (rim fractures) have been documented, including for all the latest HXLPE generations. Consequently, certain precautions must be taken during its use and close patient monitoring is necessary.

Wear Risk Prevention and Reduction in Total Hip Arthroplasty. A Personalized Study Comparing Cement and Cementless Fixation Techniques Employing Finite Element Analysis

The wear rate on Total Hip Arthroplasty (THA) entails a heavy burden for patients. This becomes more relevant with increased wear risk and its consequences such as osteolysis. In addition, osteolysis has been described in cemented and uncemented acetabular implants, and nowadays, controversy remains as to whether or not to cement the acetabular component. A personalized theoretical study was carried out to investigate which parameters have an influence on wear risk and to determine the best fixation method. Liner wear risk was assessed for two different types of fixation (cemented vs uncemented) through Finite Elements Analysis (FEA). The intraoperative variables used to determine the wear risk (cervical-diaphyseal angle, Center of Rotation positioning -COR-, head material, head size, and liner thickness) are vital parameters in surgical planning. Two types of tridimensional liner models of Ultra High Molecular Weight Polyethene (UHMWPE) were simulated through finite element analysis (FEA-over 216 cases were the core of this research). A significant relationship was found between the cervical-diaphyseal angle and wear risk (p < 0.0001), especially in valgus morphology. The acetabular fixation technique (p < 0.0001) and liner thickness (p < 0.0001) showed a significant relationship with wear risk. According to our study, using a cemented fixation with a thick liner in the right center of rotation appears to be the proper stratagy for preventing polyethylene liner wear.

Catastrophic wear in uncemented acetabular cups after Total Hip Arthroplasty. A case series

INTRODUCTION

Catastrophic wear is a rare outcome following Total Hip Arthroplasty (THA), documented to happen in less than 0.5% of THA. We present 5 cases of revision THA performed successfully on 5 patients presenting Catastrophic wear, following Total Hip Arthroplasty (THA). Specifically, Catastrophic wear cases were selected, emphasizing differential diagnosis, and a revision THA was performed in all of them and resulted in a good long-term outcome. The purpose of this case series is to contribute to the literature in evaluating both the causes of implant failure as well as the outcomes after their revisions.

METHODS

We evaluated 5 patients that presented Catastrophic rupture of acetabular implants in a 3-week period in our prosthesis center.

RESULTS

The 5 patients were females, the mean age was 56 years (44-65), the mean post-surgery time was 20 years (17-23), 4/5 of the coupling wear was ceramic-polyethylene and only one case was metal-polyethylene; 4/5 had bilateral total hip replacement. In the 5 cases a revision THA was performed, all with a successful outcome.

CONCLUSION

Catastrophic failure is an unusual entity; however, when a patient with a prosthesis presents with sudden pain, an immediate image study is indicated, with careful attention to the differential diagnosis, so as to accurately advice receiving a revision THA. The main causes of implant failure are implant duration, volumetric wear and subsequent rupture. Patients with Catastrophic wear and implant rupture, treated with a revision THA, usually have a good long-term outcome.

Soft-Tissue Balancing in Total Hip Arthroplasty

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Appropriate total hip arthroplasty (THA) reconstruction must simultaneously address component position, restoration of biomechanics, and soft-tissue balance.

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Preoperative planning for complex THA cases should include radiographic templating, a detailed case plan that contains backup implant options, and a thorough understanding of the patient's preoperative examination.

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Using a systematic approach to soft-tissue balancing in THA enhances the ability to intraoperatively execute the preoperative plan.

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In patients with preexisting deformities (e.g., dysplasia or prior surgery), increased attention to abductor function is necessary when assessing acetabular component placement and offset.

Prosthetic femoral head erosion through an acetabular component treated with revision and implant preservation

We present a case report of the rare complication of a femoral head prosthesis eroding through the acetabular liner and shell resulting in a clinical presentation of pseudo-dislocation. The patient presented with a 1-month history of progressive anterior and peritrochanteric hip pain without antecedent trauma. Radiographs demonstrated presumed hip dislocation with superior-posterior superimposition of the femoral head over the acetabular component. The patient underwent revision total hip arthroplasty with intraoperative evidence of extensive metallosis, osteolysis, and femoral head erosion through the acetabular polyethylene liner, acetabular shell, and implantation into the ilium. The femoral stem and acetabular shell were well-fixed, allowing for filling of the defect with bone void filler and cementation of a new polyethylene liner into the acetabular shell.

Complete wear-through of a metal-backed acetabular cup in an ambulatory patient

We present a rare case of a patient who presented with complete and rapid wear-through of a ceramic femoral head through a polyethylene liner and titanium acetabular cup. In addition, this patient exhibited significantly elevated serum titanium ion levels, which may serve as a marker of severe metallosis in cases where the preoperative plain radiographs underestimate signs of periarticular metal debris. The unique findings of this case include the rapid (less than 1 year time) wear-through of the femoral head in interval radiographs and the dramatic progression of metallosis and pelvic and femoral osteolysis that required both component revision. In addition, the markedly elevated titanium levels secondary to cup wear-through are also of interest and demonstrate a systemic manifestation of abrasive wear of a titanium alloy component.

Crack initiation from a clinically relevant notch in a highly-crosslinked UHMWPE subjected to static and cyclic loading

Crosslinked Ultra High Molecular Weight Polyethylene (UHMWPE), which is used as a bearing material in total joint replacement components, is subjected to static and cyclic loads in vivo. Resistance to crack initiation from a notch as a function of static and cyclic loads is not well understood for crosslinked UHMWPE. This study estimated the resistance of crosslinked UHMWPE (crosslinked with 100 kGy gamma radiation and remelted to extinguish free radicals) to crack initiation for a clinically relevant notch under both static and cyclic loading conditions. For cyclic loading, four frequencies were applied with a sine waveform and two frequencies were applied with a square waveform to independently estimate the effect of frequency and rate of loading on crack initiation. Crack initiation time and cycles to crack initiation were determined. Crack initiation time for fatigue loading conditions was substantially lower compared to static loading conditions. Crack initiation time decreased with an increase in test frequency. A square wave resulted in shorter crack initiation time compared to a sine wave. The results suggest that crosslinked UHMWPE is more resistant to crack initiation from a notch under static loading conditions compared to fatigue loading conditions.

Using Ceramic-on-Ceramic Bearings in Total Hip Arthroplasty Necessitating 44- or 46-mm Metal Shells

Ceramic-on-ceramic articulation shows the lowest wear, with a low incidence of osteolysis. A small cup limits options regarding liner thickness and femoral implant size. The purpose of this study was to evaluate the safety of a 4-mm-thick ceramic liner and the outcomes of cementless total hip arthroplasty using a 44- or 46-mm metal shell and a ceramic-on-ceramic bearing at mid- to long-term follow-up. Between May 2003 and June 2008, 80 patients (88 hips) who had hip osteoarthritis and a hypoplastic acetabulum underwent cementless total hip arthroplasty using a 44- or 46-mm metal shell and a ceramic-on-ceramic bearing. Sixty-eight of these patients (76 hips) were followed for an average of 8 years. The ceramic-related complications, clinical and radiological results, and Kaplan-Meier survivorship of these patients were evaluated. Mean Harris hip score had improved to 88 points (range, 49-100 points) at final follow-up. No ceramic fractures occurred during follow-up. All acetabular and femoral prostheses had bone ingrowth, and there was no measurable wear in any hip. In 1 patient, a radiolucent lesion occurred around the acetabular cup. Two hips underwent revision because of periprosthetic fractures. The survival rates of the acetabular cups and the femoral stems were 100% and 97.4%, respectively. The thin (4 mm) ceramic liner did not increase the risk of ceramic fracture and did not affect the mid- to long-term results and survival of cementless total hip arthroplasty using 44- or 46-mm metal shells. [Orthopedics. 2018; 41(3):e354-e359.].

The rate of wear of second-generation highly crosslinked polyethylene liners five years post-operatively does not increase if large femoral heads are used

AIMS

The increased in vivo resistance to wear of highly crosslinked polyethylene (HXLPE) in total hip arthroplasty (THA) has led to an increased use of larger articulations which have been shown to reduce the incidence of early dislocation. To date, there are few reports of the wear of larger articulations using second generation HXLPE liners. Our prospective cohort study measured the bedding-in and early wear of large (36 mm and 40 mm diameter) articulations involving a second generation X3 HXLPE liner and compared our findings with previous clinical and in vitro studies of the same material.

PATIENTS AND METHODS

The proximal penetration of the femoral head five years post-operatively was measured for 15 patients using radiostereometric analysis (RSA).

RESULTS

The median proximal bedding-in within the first post-operative year was 0.022 mm (interquartile range (IQR) -0.050 to 0.091). The median proximal rate of wear between one and five years was -0.004 mm/year (IQR -0.021 to 0.022). The rates of proximal, medial, 2D or 3D wear between one and five years post-operatively of the X3 HXLPE liner did not increase with larger articulations compared with our previous study of 32 mm articulations.

CONCLUSION

Although reassuring, the use of larger articulations requires continued monitoring to determine whether the low wear observed in the short-term continues to the mid- to long-term. Cite this article: Bone Joint J 2016;98-B:1604-10.

A Liner Breakage in Total Hip Arthroplasty after Using 1st Generation Highly Cross Linked Polyethylene Mated against 36-mm Metal Head: A Case Report

It has been known the highly cross linked polyethylene (HXLPE) has an advantage of improved wear rate. However, the alteration in mechanical properties such as decreased tensile yield and fatigue strength make concerns about fragility of HXLPE. We experienced a case of HXLPE breakage. But, this case of liner breakage happened although patient belonged to normal BMI and proper acetabular cup position so called "safe zone" on radiographs. So, we report this case with reference review.

Small diameter acetabulum and femoral head in total hip arthroplasty for developmental dysplasia of the hip, with no femoral osteotomy

We present the results of 66 total hip arthroplasties in 62 patients of mean age 46 years (24-74 years), with developmental dysplasia of the hip. In all cases the centre of rotation of the new hip was positioned at the site of the true acetabulum. In all patients cementless press fit acetabular components of small diameter (42-44 mm) were used, articulating exclusively with a 22.25 mm modular metal femoral head, without the use of bone grafts or shortening osteotomies of the femur. Despite the use of small diameter femoral heads the rate of dislocation was 3%. After an average follow-up period of 9 years (4-18 years), no revisions were required for infection, loosening or wear or implant migration. Osteolytic lesions were seen in the periacetabular region in 3 patients who were symptom free. A total of 2 revisions were required for instability and 2 patients had the wires of their trochanteric osteotomy removed because of bursitis. Leg length inequality was improved in 55% of the patients and one postoperative transient sciatic nerve lesion settled within 4 months. We believe that in patients with painful dysplastic hips, the use of small diameter implants with the centre of rotation at the true acetabulum, can give very satisfactory results, without any supplementary procedures.

Severe Periprosthetic Metallosis and Polyethylene Liner Failure Complicating Total Hip Replacement: The Cloud Sign

We present a case of an 85-year-old woman with extensive metallosis of the left hip joint secondary to prosthetic polyethelene liner dislocation and wear. Radiographs demonstrated amorphous cloudy radiodensities surrounding the prosthesis, a feature we have called the “cloud sign.” The presence of amorphous cloudy radiodensities as a radiographic sign of metallosis has not been previously described to our knowledge.

Early Fracture of a Vitamin-E-Infused, Highly Cross-Linked Polyethylene Liner After Total Hip Arthroplasty: A Case Report

CASE

A vitamin-E-infused, highly cross-linked ultra-high molecular weight polyethylene (HXLPE) acetabular liner fractured without trauma less than twelve months after its implantation in a seventy-one-year-old woman.

CONCLUSION

The remelting process utilized in the production of many commercially available HXLPE acetabular liners causes an immediate reduction in the fracture toughness of the material; however, it provides the benefit of oxidative stability, which prevents the loss of beneficial mechanical properties over time. Vitamin-E-infused HXLPE avoids the immediate decrease in fracture toughness by avoiding the remelting process. The case of our patient demonstrates that this material still can experience catastrophic failure despite acceptable component positioning.

Surveillance of Arc2f polyethylene after 15 years of implantation

BACKGROUND

To investigate the behavior of Arc2f polyethylene (PE) component after a minimum of 15 years post implantation and its possible reasons for failure.

METHODS

Between January 1988 and March 1995, 557 cementless total hip arthroplasties were performed in 578 patients. A total of 435 patients (450 hips) were followed up for 18.6 years (range 15-22).

RESULTS

At 10 years follow-up no cup needed revision surgery. After 15 years of implantation, we observed massive PE wear in 140 cups (31%) with large osteolytic lesions. A revision procedure was performed in all cases. Exchange only of the PE liner was sufficient in 78 cases, whilst in 59 the cup was also revised. PE insert thickness and the type of prosthetic head were found to be related to PE wear.

CONCLUSIONS

We postulate that the massive failure seen is attributed to the manufacturing of the PE insert. We advocate following all patients that have an implant lasting a decade after implantation for routine monitoring to identify those at risk for accelerated PE wear.

Complete Wear-Through of a Polyethylene Liner and Metal-Backed Acetabular Cup Resulting in a Unique Form of Catastrophic Total Hip Arthroplasty Failure: A Case Report

CASE

We describe a case of total hip arthroplasty failure where a cobalt-chrome femoral head completely wore through the polyethylene liner and the titanium acetabular cup. The patient subsequently underwent revision total hip arthroplasty with acetabular revision and femoral head exchange.

CONCLUSION

This case illustrates the natural history of catastrophic failure in a metal-on-polyethylene total hip arthroplasty design. If recognized earlier, this patient may have been a candidate for isolated liner and head exchange. Additionally, this case represents a unique complication in using mixed metals in total hip arthroplasty, where the harder cobalt-chrome femoral head wore completely through the much softer titanium component.

Bedding-in and true wear in two different generations cementless porous-coated acetabular cups

Radiographic measurement of polyethylene wear cannot distinguish between so-called bedding-in and true wear in porous-coated cups. In this study, sequential wear performance was compared in two different generations of two cementless porous-coated cups. Group 1 consisted of 42 Harris-Galante I cups (HG I; 32-mm femoral head) and 37 Harris-Galante II cups (HG II; 28 mm); group 2 comprised 30 ACS liners using Profile or Trilock cups (32 mm) and 53 Duraloc cups (28 mm). All liners were made of conventional polyethylene sterilised by gamma irradiation in air. All cups showed radiographic bone ingrowth. Follow-up ranged from 5 to 17 years. Anteroposterior pelvic radiographs were scanned digitally and sequential femoral head penetration was estimated using a software package based on Kim's method. Bedding-in was 0.17 ± 0.09 mm for HG I and 0.09 ± 0.02 for HG II cups (p=0.035) in group 1, and 0.60 ± 0.50 for the ACS liners and 0.11 ± 0.41 for the Duraloc cups (p<0.01) in group 2. Femoral head penetration at the end of follow-up was 1.50 ± 0.28 mm for HG I (mean 14 years) and 0.85 ± 0.01 for HG II (8 years) in group 1, and 2.86 ± 0.68 for ACS (12 years) and 0.90 ± 0.41 for Duraloc (8 years) in group 2. Mean wear was 0.09 mm/year for HG I and 0.10 for HG II in group 1, and 0.20 for the ACS liners and 0.09 for the Duraloc cups in group 2. In conclusion, sequential femoral head penetration using Kim's digitised method allows us to distinguish between bedding-in and true wear.

Short-term wear evaluation of thin acetabular liners on 36-mm femoral heads

BACKGROUND

Dislocation remains the leading cause of revision THA. One approach to decreasing prosthetic dislocation risk has been the use of larger femoral head component sizes. The upper limit of head size in metal-on-polyethylene hip arthroplasty has historically been limited because of concerns about increased wear on thin polyethylene components. It is not known to what degree this concern should apply to more wear-resistant polyethylene components.

QUESTIONS/PURPOSES

We therefore determined (1) in vitro wear rates of polyethylene liners of varying thicknesses, (2) whether there were differences in the microscopic wear characteristics as a function of polyethylene thickness, and (3) whether thin polyethylene components resulted in early catastrophic failures.

METHODS

We used a hip wear simulator to compare the wear performance of 12 highly crosslinked polyethylene acetabular inserts. The internal diameter of all components was 36 mm, and there were three samples tested of each thickness (1.9, 3.9, 5.9, or 7.9 mm). Testing was conducted for 2.4 million cycles. Gravimetric mass loss was converted to volumetric loss, which was subsequently converted to theoretical linear penetration rates.

RESULTS

Wear rates decreased with increasing polyethylene thickness. Mean ± SD wear rates for the 1.9-, 3.9-, 5.9-, and 7.9-mm groups were 5.0 ± 0.5, 3.2 ± 0.3, 2.5 ± 1.1, and 2.2 ± 1.3 mm(3)/million cycles, respectively (p < 0.016). Calculated penetration rates were 0.015, 0.012, 0.011, and 0.010 mm/million cycles, respectively (p < 0.016). There were no catastrophic failures in any group.

CONCLUSIONS

Thinner polyethylene components demonstrated higher wear rates, although even the highest wear rate observed in the thinnest polyethylene specimen was lower than that commonly reported for noncrosslinked polyethylene components. While encouraging, these findings should be validated in vivo before clinical recommendations can be made.

Catastrophic fracture of a stable metal acetabular component

Various modes of failure of primary and revision total hip arthroplasty have been well documented in the literature over the past 30 years. Concerns over polyethylene wear, osteolysis, and hypersensitivity reactions leading to component loosening and early revision have been evaluated and reported in the literature. Routine follow-up is important to monitor for postoperative issues that might lead to the subsequent need for revision.This article describes a case of a 64-year-old man who initially presented 11 years prior with an intertrochanteric fracture, which failed secondary to varus alignment and femoral head osteonecrosis. The fixation was converted to a total hip replacement using the S-ROM system (DePuy, Warsaw, Indiana). Subsequently, the patient was lost to follow-up after primary total hip arthroplasty and presented with a catastrophic fracture of the metal acetabular cup system. The failure was suggested by clinical presentation and confirmed by imaging studies showing a fractured acetabular shell with femoral head prosthesis resting in the superolateral ileum. The contributing factors that resulted in mechanical failure were polyethylene wear and component fracture. The acetabular component was revised with an in-growth cementless trabecular metal multihole cup (Zimmer, Warsaw, Indiana) with bone grafting of acetabular defects.Routine assessments help educate patients and allow careful monitoring by physicians while establishing a radiographic timeline for the identification, progression, or lack of postoperative complications.

Total hip arthroplasty using a cylindrical cementless stem in patients with a small physique

We performed total hip arthroplasty using an anatomic medullary locking cementless stem for small-physique patients from 1988 to 1995. We conducted a retrospective study of 50 joints in 44 cases, including 40 developmentally dysplastic hips followed for 12 to 20 years (average, 15.1 years). Average height and body weight were 152 cm and 56 kg (5.0 ft and 124 lb), respectively, with an average body mass index of 24.2. Twelve joints (24%) were revised for acetabular-sided failures. Forty-eight stems (96%) showed bone ingrowth fixation, and there were no unstable stems. The simple cylindrical shape of the distal portion of the AML stem was less affected by deformity of the proximal femur of developmental dysplasia of the hip in patients with a small physique, and both clinically and radiologically good results were confirmed at long-term follow-up.

Direct comparison of polyethylene wear in cemented and uncemented acetabular cups

Background

It has been indicated that, in the long term, the rate of wear and the degree of osteolysis observed with uncemented acetabular components are greater than those associated with cemented cups, but most studies which compare the wear characteristics of cementless with cemented cups have used historical controls. We report a direct comparison of wear of a cemented and an uncemented cup with similar design, polyethylene, and sterilization method.

Materials and methods

The study cohort includes 92 patients who were operated in 1997 with primary total hip replacement and have been followed for a period of 9–10 years. All patients were operated by posterolateral approach. In patients 70 years or older we used a cemented cup, in those 60 years or younger we used an uncemented cup, and in patients between 60 and 70 years we used either a cemented or uncemented cup as decided by the surgeon. At follow-up, radiographic imaging was obtained as standard anterioposterior view of the pelvis, and mean wear was determined as described by Livermore et al.

Results

The overall wear of the cemented acetabular components was 1.07 ± 0.78 mm, and that of the uncemented cups was 1.18 ± 0.61 mm (P = 0.529). Wear was significantly associated with male sex (P = 0.003), younger age (P = 0.003), and degree of inclination (P < 0.001), but wear was not significantly associated with cemented versus uncemented cup (P = 0.437).

Conclusion

Our findings in this 9–10-year follow-up study suggest that cementless cups wear no more than cemented cups of similar design.

Severe metallosis after total elbow arthroplasty-a case report

We present a case of severe metallosis after total elbow arthroplasty in a female patient presenting with manifestations resembling a septic loosening. We discuss the clinical and the operative findings as well as the outcome of this uncommon complication. A review of the literature regarding the pathogenesis, radiographic appearance, and management of metallosis in prosthetic joints is presented.

Complete polyethylene wear-through and secondary breakage of the expansion cup in a ceramic-polyethylene total hip

INTRODUCTION

Catastrophic polyethylene failure is an uncommon complication of ceramic-on-polyethylene total hip arthroplasty (THA) because of the favourable tribological characteristics of these implants. We present a case of a 50-year-old woman who formerly underwent bilateral ceramic-on-polyethylene THA with expansion acetabular cups and eleven years later presented with unilateral THA dislocation, secondary to catastrophic polyethylene failure and metal shell fracture.

CASE PRESENTATION

The patient came to our hospital for worsening pain in her left hip and an acute incapacity to bear weight on her left lower limb. Twelve and eleven years earlier she had undergone bilateral ceramic-on-polyethylene THA with acetabular expansion components of identical size on both sides. Radiographically, the left femoral head appeared superiorly dislocated and severe polyethylene wear was detected. The inclination angles of the left and right cups were 60° and 44°, respectively. The patient underwent left acetabular revision, and complete polyethylene wear-through with fracture of a cranial lobe of the expansion metal shell was noted at surgery. One large osteolytic lesion in the roof of the acetabulum and diffuse periarticular metallosis were also present. These findings required the use of a Burch–Schneider reinforcement cage. Two years later the patient is functioning well and has full autonomy in her activities of daily living.

CONCLUSION

The correct inclination of the acetabular component is necessary to prevent accelerated polyethylene wear in THA, even though favourable articular bearing surfaces have been used (e.g., ceramic-on-polyethylene coupling). Should the cup appear well fixed and fairly oriented on follow-up radiographies, the early detection of severe polyethylene wear may permit a revision of only the femoral head and acetabular liner.

Long-term results of the ABG-1 hydroxyapatite coated total hip arthroplasty: analysis of 111 cases with a minimum follow-up of 10 years

INTRODUCTION

Medium-term studies of ABG-1 cementless total hip arthroplasty have shown favorable functional results with excellent femoral component fixation but an abnormally high rate of periacetabular component osteolysis, which may require early revision.

HYPOTHESIS

The periacetabular osteolysis rate increases with time with the ABG-1 implant, leading to a high revision rate.

OBJECTIVE

The objective of this study was to test this hypothesis with a minimum follow-up of 10 years and evaluate the progression of periacetabular osteolysis and its consequences on implant fixation.

MATERIAL AND METHODS

A continuous series of 111 ABG-1 cementless prostheses implanted by a single operator with a theoretical minimum follow-up of 10 years. Seventy-five implants were analyzed with a mean follow-up of 13 years. All the prostheses had been implanted via a posterolateral approach and consisted of a 28 mm cup matching a head in zirconia and an antidislocation rim design high-density polyethylene insert.

RESULTS

Twelve cups were revised because of progressive retroacetabular osteolysis. The revisions were performed systematically although there was no pain or gross cup loosening. The revisions included resection of the granuloma, cavity filling with morselized bone grafts, and implantation of new uncemented ABG-2 cups in eight cases or cemented cups associated with a support ring in the four other cases. Thirty-two (48.5%) of the cups still in place at the end of the follow-up evaluation presented moderate and asymptomatic radiographic osteolysis, inciting close subsequent observation. No predictive factor of osteolysis onset was identified (age, body mass index, polyethylene wear, or cup orientation). None of the femoral stems was changed because of osteolysis: the only two femoral revisions resulted from periprosthetic fracture and one case of bipolar loosening. The femoral osteolysis images were small and all limited to zones 7a (18.8% of cases), 1a, and 1b (65.2% of cases). The overall survival rate of the series at 13 years of follow-up was 80.5%; the cup survival rate was 83.2%; the femoral implant, 94.3%; and failure of the femoral stem secondary to aseptic loosening was only 1.3%.

DISCUSSION, CONCLUSION

This long-term study confirms the high frequency of retroacetabular osteolysis of ABG-1 prostheses surpassing the osteolysis rate of other uncemented cups with a polyethylene insert. The absence of predictive criteria of osteolysis occurrence and the lack of symptoms warrants periodic follow-up of patients with ABG-1 cups and, if necessary, early repair of bone stock loss with grafts combined with acetabular cup revision. This procedure remains simple as long as performed before the onset of massive bone destruction, confirming the proposed revisions in this series were judicious. This study also confirms the excellent long-term fixation of the ABG-1 femoral stems derived from the osteointegration and proximal seal around the hydroxyapatite coating.

The natural history of metallosis from catastrophic failure of a polyethylene liner in a total hip

We report on a case of metallosis initially presumed to be heterotopic ossification based on radiologic findings. A 68-year-old man with a total hip arthroplasty experienced failure of the polyethylene liner, resulting in articulation of the ceramic head with the titanium acetabular shell. During revision surgery, extensive metallic debris was evident macroscopically throughout the periprosthetic tissue and was confirmed histologically to be metallosis.

Ultra high molecular weight polyethylene: mechanics, morphology, and clinical behavior

Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been used for over four decades as a bearing surface in total joint replacements. The mechanical properties and wear properties of UHMWPE are of interest with respect to the in vivo performance of UHMWPE joint replacement components. The mechanical properties of the polymer are dependent on both its crystalline and amorphous phases. Altering either phase (i.e., changing overall crystallinity, crystalline morphology, or crosslinking the amorphous phase) can affect the mechanical behavior of the material. There is also evidence that the morphology of UHMWPE, and, hence, its mechanical properties evolve with loading. UHMWPE has also been shown to be susceptible to oxidative degradation following gamma radiation sterilization with subsequent loss of mechanical properties. Contemporary UHMWPE sterilization methods have been developed to reduce or eliminate oxidative degradation. Also, crosslinking of UHMWPE has been pursued to improve the wear resistance of UHMWPE joint components. The 1st generation of highly crosslinked UHMWPEs have resulted in clinically reduced wear; however, the mechanical properties of these materials, such as ductility and fracture toughness, are reduced when compared with the virgin material. Therefore, a 2nd generation of highly crosslinked UHMWPEs are being introduced to preserve the wear resistance of the 1st generation while also seeking to provide oxidative stability and improved mechanical properties.

Massive wear and metallosis of an Acetabular Cup System presenting as pseudodislocation

In primary and revision total hip arthroplasty (THA), the acetabular component continues to pose greater challenges than the femoral component. Numerous factors lead to polyethylene wear, which subsequently affects primary THA survival. Progressive polyethylene wear is associated with the occurrence of osteolysis, especially overlying the acetabulum, which can lead to component loosening and subsequent revision. Polyethylene failure usually manifests as massive liner wear up to the metal shell, fracture of the liner, or a combination of both. There is often a small amount of metallosis associated with this pathology. To our knowledge, massive wear of the acetabular metal shell, however, has not previously been reported in the literature. This article describes a case of massive wear through a polyethylene liner and the acetabular metal shell of an Acetabular Cup System (DePuy, Leeds, United Kingdom) that presented as an apparent dislocation 13 years following the index operation. The pseudodislocation was intraoperatively found to be penetration of the femoral head through the acetabular shell. The acetabular component was consequently revised to a larger cementless cup. The femoral component was mechanically stable and required no revision. Patients with long-standing Acetabular Cup System THA may experience acetabular metal shell wear-through phenomena presenting as a pseudodislocation, and this possibility should be taken into consideration during preoperative planning.

A comparison of the outcome of cemented all-polyethylene and cementless metal-backed acetabular sockets in primary total hip arthroplasty

We compared, after a 10-year-minimum follow-up, the outcome of 50 cemented all-polyethylene Charnley acetabular sockets with that of 51 cementless metal-backed sockets in 2 comparable cohorts of young patients. Although the revision rate for the cemented and cementless group was 28% and 35%, respectively, the revision rate for aseptic loosening was 28% for the cemented and 12% for the cementless group. The mean polyethylene wear was 0.112 and 0.114 mm/y, respectively, for the 2 groups. Linear osteolysis was observed in 18 of 50 cemented sockets. Expansile osteolysis presented in 10 of 51 cementless sockets and only in one of the cemented sockets. In conclusion, cementless components had more durable fixation than cemented components. However, they presented more aggressive expansile osteolysis caused by the coexistence of polyethylene and metal debris.

Evaluation of two surgical techniques for acetabular reconstruction in total hip replacement for congenital hip disease: results after a minimum ten-year follow-up

We have evaluated the results of total hip replacement in patients with congenital hip disease using 46 cemented all-polyethylene Charnley acetabular components implanted with the cotyloplasty technique in 34 patients (group A), and compared them with 47 metal-backed cementless acetabular components implanted without bone grafting in 33 patients (group B). Patients in group A were treated between 1988 and 1993 and those in group B between 1990 and 1995. The mean follow-up for group A was 16.6 years (12 to 18) and the mean follow-up for group B was 13.4 years (10 to 16). Revision for aseptic loosening was undertaken in 15 hips (32.6%) in group A and in four hips (8.5%) in group B. When liner exchange was included, a total of 13 hips were revised in group B (27.7%). The mean polyethylene wear was 0.11 mm/yr (0.002 to 0.43) and 0.107 mm/yr (0 to 0.62) for groups A and B, respectively. Polyethylene wear in group A was associated with linear osteolysis, and in group B with expansile osteolysis. In patients with congenital hip disease, when 80% cover of the implant can be obtained, a cementless acetabular component appears to be acceptable and provides durable fixation. However, because of the type of osteolysis arising with these devices, early exchange of a worn liner is recommended before extensive bone loss makes revision surgery more complicated.

Catastrophic failure of ceramic-polyethylene bearing total hip arthroplasty

Complications of ceramic-polyethylene bearing total hip arthroplasty (THA) include osteolysis, loosening, dislocation, and component failure. Catastrophic acetabular component failure involves severe damage to both the polyethylene liner and metal shell. This case study presents the first reported complete wear-through of the acetabular portion of a ceramic-polyethylene arthroplasty presenting as a dislocation and a review of the literature. In this study, a patient's alumina ceramic femoral head penetrated the polyethylene liner and titanium shell and presented as a dislocated THA. The contributing factors for this catastrophic failure include young patient age, high activity level, thin polyethylene liner, backside wear, component positioning, polyethylene sterilization with gamma irradiation in air, and lack of appropriate follow-up. Revision THA was performed without complications.

Ten-year survivorship of the Anatomique Benoist Girard I total hip arthroplasty

The Anatomique Benoist Girard (ABG) I total hip arthroplasty has been widely used in Europe since 1989. Two recent midterm reports have shown high rates of component failure secondary to polyethylene wear. To further investigate this issue, our study prospectively follows 157 consecutive primary total hip arthroplasties using the ABG I prosthesis at an average follow-up of 10 years. Clinical outcomes have been excellent, although the incidence of thigh pain was 7.2%. Radiographic evaluation of the cup showed eccentric polyethylene wear in 93.6% of the patients. The average polyethylene linear wear was 2.40 mm, whereas the average annual wear rate was 0.25 mm/y. There were 7 hips (5.6%) with severe periacetabular osteolysis. Nine revisions were performed for loosening or wear. The overall component survival rate was 92.6%. The overall survival rate was 92.6% (confidence interval, 78.55-96.47) for the acetabular component and 96.3% (confidence interval, 85.67-100) for the femoral component. Although the clinical and radiographic results of the ABG I total hip arthroplasty in this series have been acceptable, high rates of polyethylene wear, most likely related to sterilization by gamma-irradiation in air, have been the limiting factor in the long-term success of this design.

Catastrophic failure of a modular revision total hip polyethylene insert

Early catastrophic failure of a modular polyethylene component is a potential problem after revision total hip arthroplasty. We describe an unusual case of polyethylene failure that occurred within 18 months of implantation in which no obvious technical error or mechanical failure was identified. The acetabular polyethylene insert was prepared with gas plasma sterilization, and the shelf life was 4 months. Radiographic evaluation used generalized Hough transforms to assess the cup articulation. We identified cup penetration of 2.8 mm before revision and catastrophic destruction of the polyethylene liner at the time of revision. Possible factors implicated for failure included a thin polyethylene liner, increased hip separation, femoral head mismatch, and the high activity level of a younger patient. We believe that this case report highlights the need for future investigations of these subtle factors.

Long-term results of uncemented acetabular cups with an ACS polyethylene liner. a 14-16-year follow-up study

We assessed the clinical and radiographic results of 40 porous-coated acetabular cups with an Acetabular Cup System polyethylene liner over a minimum 14-year follow-up. Femoral head penetration was estimated using a software package. Fifteen cups were revised, 11 due to polyethylene liner rupture. All cups but two were radiographically stable, and 11 hips showed acetabular osteolysis. The overall femoral head penetration rate in hips without liner fracture with reference to the early penetration point was 0.1188+/-0.070 mm per year. Polyethylene liner fractures were associated with higher early femoral head penetration (P<0.0001) and a vertical cup position (P=0.0016). The 14-year survival without cup revision for any reason was 63.9%, 71.8% with no ACS polyethylene liner fracture and 65.3% with no acetabular osteolysis. Most cups showed a good clinical outcome in general, but major Acetabular Cup System liner failure and osteolysis were frequent. Patients with the ACS cups still in place should be monitored closely.

Five-year clinical, radiological and postmortem results of the Cambridge Cup in patients with displaced fractures of the neck of the femur

The Cambridge Cup has been designed to replace the horseshoe-shaped articular cartilage of the acetabulum and the underlying subchondral bone. It is intended to provide physiological loading with minimal resection of healthy bone.

The cup has been used in 50 women with displaced, subcapital fractures of the neck of the femur. In 24 cases, the cup was coated with hydroxyapatite. In 26, the coating was removed before implantation in order to simulate the effect of long-term resorption.

The mean Barthel index and the Charnley-modified Merle d’Aubigné scores recovered to their levels before fracture. We reviewed 30 women at two years, 21 were asymptomatic and nine reported minimal pain. The mean scores deteriorated slightly after five years reflecting the comorbidity of advancing age. Patients with the hydroxyapatite-coated components remained asymptomatic, with no wear or loosening. The uncoated components migrated after four years and three required revision. This trial shows good early results using a novel, hydroxyapatite-coated, physiological acetabular component.

The acetabular insert-metal backing interface: an additional source of polyethylene wear debris

In cementless acetabular arthroplasty, the interface between the metal backing and the ultra-high-molecular-weight polyethylene acetabular insert surface is a potential source of polyethylene debris. This study of 55 early-generation acetabular inserts found that severe wear of the convex insert surface correlates with osteolysis. Wear of the concave insert surface did not correlate strongly with osteolysis probably owing to prevalent micromotion and wear at the convex surface interface. Although concern over linear wear predominates with contemporary designs, if initial liner engagement is compromised or locking mechanism failure occurs with time, the convex insert surface again may become a significant source of debris contributing to osteolysis.

Polyethylene liner failure in second-generation Harris-Galante acetabular components

Polyethylene liner failure of cementless acetabular components has been reported to be the most common complication of current modular cups. We performed a retrospective review of 128 consecutive primary total hip arthroplasties in 111 patients who had a second-generation Harris-Galante cup (Harris-Galante II, Zimmer, Warsaw, Ind). The mean length of the follow-up period was 8.0 years (range 5-12.9 years), with 26 cups (20.2%) having undergone revision by that time. Twenty-two hips (17.3%) had failure of the polyethylene liner. We found that polyethylene liner failure remains the main cause of revision of this modular cup. The main difference between our population of patients and other populations that have used this cup and liner is our population's cultural inclination toward squatting and leg crossing, body positions that increased the risk of impingement and eccentric wear.

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.

Évaluation au recul de 5 ans de 100 cupules impactées sans ciment de type Duraloc®

PURPOSE OF THE STUDY

The longevity of an acetabular implant depends in part on its resistance to mechanical stress. Long-term stability of an uncemented cup requires stable primary fixation. This can be achieved with press-fit components.

MATERIAL AND METHODS

One hundred forty-nine Duroloc press-fit acetabular implants were studied after a minimum follow-up of 60 months. Among these 149 cups, 100 were analyzed with a mean follow-up of 60 months. Twenty-two patients were lost to follow-up, 19 were contacted by telephone, and eight had died. Clinical and radiological criteria were used to assess outcome. Digitalized x-rays were processed with Imagika (View Tec, Saint-Maurice, France) to determine the position of the implant in two-dimensional space, inclinaison, anteversion, polyethylene wear, bone-implant contact, and presence of ossifications. Seventy percent of the patients underwent arthroplasty for degenerative hip disease.

RESULTS

The cohort included 40 women and 60 men. Mean age at surgery was 59.4 years, range 30-80 years. The Postel-Merle-d'Aubigne score improved from 10 to 16. Mean polyethylene wear was 0.5 mm with an annual rate of 0.087 mm/yr. Among the 57 cup-bone spaces present postoperatively, 41 had filled at last follow-up (78%). There were no cases of osteolysis. Peri-prosthetic ossifications were observed in 50 patients (16 stage I, 12 stage II, 19 stage II, and 3 stage IV). Medial displacement of the cup > 4 mm was observed in one patient and ascension > 4 mm in four patients who had no other sign of loosening. Complications were: dislocation (n=15), phlebitis (n=2), sciatalgia (n=1) and infection (n=1).

DISCUSSION

This retrospective series revealed an unacceptable dislocation rate with no correlation with implant positioning error in comparison with the biomechanical position of the healthy hip. The non-hemispheric shape of the implant and the beveled edge of the polyethylene insert could be implicated, particularly since none of the implants had a polyethylene overhang. The mean annual wear (0.087 mm) was relatively high compared with cemented cups. Age was the only factor correlated with wear. Migrations were difficult to interpret. Medialization or ascension of the implant was not associated with any clinical sign suggestive of loosening. The poor reproducibility of the x-rays cannot explain these findings. Secondary repositioning of the implant might be involved.

CONCLUSION

The high rate of dislocation and the frequency of excessive wear have led us to abandon this implant for more hemispheric cups.

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.

Analysis of retrieved uncemented porous-coated acetabular components in patients with and without pelvic osteolysis

Retrieved polyethylene liners and femoral heads from a consecutive series of revision components of one design were examined. All patients had Long-Term Stable Fixation (OsteoTechnology International, Timonium, Md) total hip arthroplasties (THAs) implanted between 1987 and 1992. The retrieved femoral heads and liners from patients with osteolysis were compared to those without osteolysis. Patients with osteolysis had significantly thinner polyethylene (5.1 mm versus 7.4 mm, P<.01 ) and a higher linear wear rate (0.5 mm/y versus 0.3 mm/y, P=.05). The average femoral head surface roughness also was significantly greater in patients with osteolysis (67 nm versus 35 nm, P<.05). Patients with osteolysis had more total volumetric wear, total linear wear, and volumetric wear rate compared to patients without osteolysis. Age, obesity index, time in situ, and cup inclination were not different between the two groups. Excessive polyethylene wear, probably accelerated by surface roughness of the femoral heads, was associated with pelvic osteolysis in these patients.

Material fundamentals and clinical performance of plasma-sprayed hydroxyapatite coatings: a review

The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has aroused as many controversies as interests over the last decade. Although faster and stronger fixation and more bone growth have been revealed, the performance of HA-coated implants has been doubted. This article will initially address the fundamentals of the material selection, design, and processing of the HA coating and show how the coating microstructure and properties can be a good predictor of the expected behavior in the body. Further discussion will clarify the major concerns with the clinical use of HA coatings and introduce a comprehensive review concerning the outcomes experienced with respect to clinical practice over the past 5 years. A reflection on the results indicates that HA coatings can promote earlier and stronger fixation but exhibit a durability that can be related to the coating quality. Specific relationships between coating quality and clinical performance are being established as characterization methods disclose more information about the coating.

Surgical treatment of pelvic osteolysis

Sixty-eight well-fixed acetabular cups with osteolysis in the pelvis and polyethylene wear were identified from a series of 124 reoperations for failed cementless sockets. The well-fixed sockets requiring reoperation were subdivided based on whether the liner was exchanged and lytic lesion grafted (Type I case) or the socket was removed and a complete revision was done (Type II case). In 40 patients (Type I cases), the polyethylene liner was exchanged and the osteolytic lesions were debrided. Allograft bone chips were packed into the lytic defect in 29 patients. In the remaining 11 patients, the lesions were debrided but not grafted. At final followup, all of the acetabular components were radiographically stable. No new osteolytic lesions were identified. Approximately 1/3 of the lesions had resolved completely regardless of whether they were grafted. The remaining 2/3 had decreased in size. In 28 patients (Type II cases), the socket was revised. Both strategies were successful in arresting the process of osteolysis during the course of this study (mean, 3.5 years). However, removal of well-fixed sockets was associated with significantly more bone loss.

Athletic activity after joint replacement

The first decade of the 21st century has been declared the "Bone and Joint Decade" by 35 nations and 44 states in the United States as of March 2001. It is not surprising that Americans are interested in musculoskeletal disease and the treatment of bone and joint disorders because our population is aging, the prevalence of arthritic joints is increasing, and senior Americans are demonstrating a strong desire to stay active in activities of daily living and athletics. One of the most successful treatments for painful arthritic joints, which limit activity, is total joint replacement, which predictably relieves pain and improves function. Much has been written about the technical aspects of total joint arthroplasty. Less has been written about safe and appropriate activities for patients who have had joint replacement operations. This article evaluates athletic activity after joint replacement by reviewing the orthopaedic literature and surveying members of The Hip Society, The Knee Society, and The American Shoulder and Elbow Surgeons Society. The authors have developed consensus recommendations for appropriate athletic activity for patients who have had joint replacement operations. This article is intended to serve as a guide for orthopaedic surgeons and primary care physicians who give patients recommendations for athletic activity after joint replacement. This article is also intended to stimulate further research in the area of athletic activity after total joint arthroplasty.