Postmortem study of femoral osteolysis associated with metal-on-metal articulation in total hip replacement: an analysis of nine cases

Nanoscale ZnO doping in prosthetic polymers mitigate wear particle-induced inflammation and osteolysis through inhibiting macrophage secretory autophagy

Wear particles produced by joint replacements induce inflammatory responses that lead to periprosthetic osteolysis and aseptic loosening. However, the precise mechanisms driving wear particle-induced osteolysis are not fully understood. Recent evidence suggests that autophagy, a cellular degradation process, plays a significant role in this pathology. This study aimed to clarify the role of autophagy in mediating inflammation and osteolysis triggered by wear particles and to evaluate the therapeutic potential of zinc oxide nanoparticles (ZnO NPs). We incorporated ZnO into the prosthetic material itself, ensuring that the wear particles inherently carried ZnO, providing a targeted and sustained intervention. Our findings reveal that polymer wear particles induce excessive autophagic activity, which is closely associated with increased inflammation and osteolysis. We identified secretory autophagy as a key mechanism for IL-1β secretion, exacerbating osteolysis. Both in vitro and in vivo experiments demonstrated that ZnO-doped particles significantly inhibit autophagic overactivation, thereby reducing inflammation and osteolysis. In summary, this study establishes secretory autophagy as a critical mechanism in wear particle-induced osteolysis and highlights the potential of ZnO-doped prosthetic polymers for targeted, sustained mitigation of periprosthetic osteolysis.

What is the long-term survivorship, complication profile, and patient reported outcomes after Birmingham hip resurfacing?

Introduction

When indicated, Birmingham Hip Resurfacing (BHR) presents a viable alternative to total hip arthroplasty (THA), but there remain questions about the long-term outcomes of BHR. Therefore, we asked: 1) what are the long-term patient-reported outcomes and 2) survivorship rates following BHR; 3) what are the causes for revision surgery after BHR? and 4) how have these outcomes compared to THA at long-term follow-up.

Methods

A query of PubMed, MEDLINE, Scopus, and Cochrane in September 2023 was performed. Articles were included if they reported BHR survivorship rates at ≥10 years. Survivorship was defined as an all-cause revision of any BHR component. This review encompasses 26 articles, totaling 13,103 hips. Mean follow-up ranged from 6.0 to 20.9 years, but each study had at least a subgroup analysis for ≥10-year follow-up.

Results

Five studies compared preoperative and postoperative PROs for BHR, with four reporting improvement in at least one PRO after 10-year follow-up. Overall, survivorship rates ranged from 83% to 100% across diverse long-term timeframes, with 25 of 26 studies reporting 10-year survivorship rates greater than 87%. The primary reasons for revisions were implant loosening (22%), adverse reactions to metal debris (21.2%), and fractures of any kind (17.2%). In the six studies that compared BHR to THA, long-term survivorship was similar while BHR exhibited slightly superior activity levels.

Conclusion

The findings from this study suggested favorable long-term survivorship and postoperative outcomes of BHR. In studies comparing long-term BHR and THA, survivorship was comparable, with BHR potentially providing enhanced postoperative activity levels.

Metal-on-Metal Hip Arthroplasty: A Comprehensive Review of the Current Literature

Metal-on-metal (MoM) total hip arthroplasty has been widely used since the end of the 20th century, although rates have now decreased due to concerns regarding adverse reactions and failure rates. The MoM implant has been replaced with other materials, such as ceramic-on-ceramic (CoC) and metal-on-polyethylene (MoP). This literature review looks at the past and present use of MoM prostheses to assess whether the turn away from MoM use is justified. Online literature searches were performed on PubMed, Ovid Medical Literature Analysis and Retrieval System Online (MEDLINE), and Web of Science online databases using the search terms "MoM and (ARMD and ALVAL)" (ARMD: adverse reaction to metal debris; ALVAL: aseptic lymphocyte-dominant vasculitis-associated lesion). A total of 64 relevant titles were included in the review. Although risk factors for adverse reactions and the causes of ARMD are generally agreed upon, more work is required to further understand the specific thresholds of blood metal ion levels that can be used to consistently identify ARMD and excessive metal wear-debris in patients who have not had their MoM implants revised. Metal-on-metal devices are not an acceptable option for total hip arthroplasties (THAs) in their current formulation due to the high rate and risk of ARMD. Some MoM hip resurfacing operations are appropriate for very carefully selected patients who are fully aware of the risks posed by the implant. It is recommended that device-specific thresholds for metal ion levels be developed to identify patients at risk of ARMD locally and systemically while using auxiliary tools to assist diagnosis, such as metal artefact reduction sequences (MARS)-MRI and hip scoring tools. Further work should investigate device-specific blood metal ion levels, the systemic effects of raised metal ion concentrations secondary to MoM arthroprosthetic wear, and the potential risks of ARMD caused by wear from tapered stems (including the implications this has for patients with CoC and MoP prostheses).

Noninfectious tissue interactions at periprosthetic interfaces

The success of hip arthroplasty is based on modern materials in addition to the continuous development of surgical techniques and clinical experience gained over six decades. The biocompatible implant materials used in hip arthroplasty can be textured or coated with biomimetic surfaces to ensure durable component ingrowth and moderate host response. Material integrity plays a critical role in the durability of the stable interface between implant components and periprosthetic tissues. Inflammation at the interfaces due to the release of degradation products from the implant materials is one of the causes of hip arthroplasty failure. This review summarizes the implant materials currently used in hip arthroplasty, their preclinical testing and the postoperative neogenesis of periprosthetic tissues, and the interactions of periprosthetic bone and the implant materials at the periprosthetic interfaces.

Are the Wear and Osteolysis Outcomes Different between Annealed and Remelted First-Generation Highly Crosslinked Polyethylene after Long-Term Implantation?

First-generation highly crosslinked polyethylene (HXLPE) was developed to reduce polyethylene wear debris and subsequent osteolysis. Two thermal stabilization strategies were developed, annealing and remelting, to remove free radicals remaining in the polymer. Both types of HXLPEs have demonstrated better wear resistance to conventional polyethylene in hip arthroplasty. However, few studies have directly compared the mid- to long-term clinical outcomes of first-generation HXLPEs. We sought to address the following research questions: (1) is there a difference between the revision reasons for HXLPE formulations (annealed and remelted), (2) is there a difference in oxidation between annealed and remelted HXLPEs, (3) is there a difference in the linear penetration rate of annealed and remelted HXLPEs, and (4) does the formulation of first-generation HXLPEs affect the prevalence of osteolysis? A total of 129 first-generation HXLPE acetabular liners were collected in a multicenter retrieval program. These components were implanted for 5 or more years and were fabricated from annealed or remelted HXLPE. Reasons for revision, body mass index, age, sex, and activity levels were collected from medical records. Oxidation was measured at four regions of interest: bearing surface, backside surface, locking mechanism, and rim. Liner penetration was directly measured from retrievals using a micrometer. Osteolysis was reported in the operative notes by the revising surgeon and a thorough review of the operative notes and radiographs. Revision reasons included infection, instability, pain, and loosening. The annealed liners had higher oxidation indices than remelted liners. There was no difference in linear penetration rates between cohorts. There was no difference in osteolysis prevalence between cohorts. We found remelted HXLPE to be more oxidatively stable than annealed HXLPE but did not find a significant difference in the linear penetration rates or the prevalence of osteolysis. Our findings demonstrate sustained long-term wear resistance of both cohorts of HXLPE. We did not find evidence to support a long-term clinical difference between the formulations of HXLPE.

Serum cobalt concentrations remain at low levels at a minimum of 20 years following metal-on-metal total hip arthroplasty

Aims

Second-generation metal-on-metal (MoM) articulations in total hip arthroplasty (THA) were introduced in order to reduce wear-related complications. The current study reports on the serum cobalt levels and the clinical outcome at a minimum of 20 years following THA with a MoM (Metasul) or a ceramic-on-polyethylene (CoP) bearing.

Methods

The present study provides an update of a previously published prospective randomized controlled study, evaluating the serum cobalt levels of a consecutive cohort of 100 patients following THA with a MoM or a CoP articulation. A total of 31 patients were available for clinical and radiological follow-up examination. After exclusion of 11 patients because of other cobalt-containing implants, 20 patients (MoM (n = 11); CoP (n = 9)) with a mean age of 69 years (42 to 97) were analyzed. Serum cobalt levels were compared to serum cobalt levels five years out of surgery.

Results

The median cobalt concentration in the MoM group was 1.04 μg/l (interquartile range (IQR) 0.64 to 1.70) at a mean of 21 years (20 to 24) postoperatively and these values were similar (p = 0.799) to cobalt levels at five years. In the CoP control group, the median cobalt levels were below the detection limit (< 0.3 μg/l; median 0.15 μg/l, IQR 0.15 to 0.75) at 20 years. The mean Harris Hip Score was 91.4 points (61 to 100) in the MoM group and 92.8 points (63 to 100) in the CoP group.

Conclusion

This study represents the longest follow-up series evaluating the serum cobalt levels after 28 mm head MoM bearing THA and shows that serum cobalt concentrations remain at low levels at a mean of 21 years (20 to 24) after implantation.

Cite this article:Bone Joint Res. 2020;9(3):145–150.

Evaluation of Aerosol Electrospray Analysis of Metal-on-Metal Wear Particles from Simulated Total Joint Replacement

Wear is a common cause for aseptic loosening in artificial joints. The purpose of this study was to develop an automated diagnostical method for identification of the number and size distribution of wear debris. For this purpose, metal debris samples were extracted from a hip simulator and then analyzed by the electrospray method combined with a differential mobility analyzer, allowing particle detection ranging from several nanometers up to 1 µm. Wear particles were identified with a characteristic peak at 15 nm. The electrospray setup was successfully used and validated for the first time to characterize wear debris from simulated total joint replacement. The advantages of this diagnostic method are its time- and financial efficiency and its suitability for testing of different materials.

Trends in total hip arthroplasty

This article discusses developments in total hip arthroplasty related to the use of highly cross-linked polyethylene (HXLPE) liner material as the new standard of care for acetabular cup articulation surfaces. The pathologic implications of metal-on-metal hip prostheses in asymptomatic patients also are discussed.

Immunological Responses to Total Hip Arthroplasty

The use of total hip arthroplasties (THA) has been continuously rising to meet the demands of the increasingly ageing population. To date, this procedure has been highly successful in relieving pain and restoring the functionality of patients’ joints, and has significantly improved their quality of life. However, these implants are expected to eventually fail after 15–25 years in situ due to slow progressive inflammatory responses at the bone-implant interface. Such inflammatory responses are primarily mediated by immune cells such as macrophages, triggered by implant wear particles. As a result, aseptic loosening is the main cause for revision surgery over the mid and long-term and is responsible for more than 70% of hip revisions. In some patients with a metal-on-metal (MoM) implant, metallic implant wear particles can give rise to metal sensitivity. Therefore, engineering biomaterials, which are immunologically inert or support the healing process, require an in-depth understanding of the host inflammatory and wound-healing response to implanted materials. This review discusses the immunological response initiated by biomaterials extensively used in THA, ultra-high-molecular-weight polyethylene (UHMWPE), cobalt chromium (CoCr), and alumina ceramics. The biological responses of these biomaterials in bulk and particulate forms are also discussed. In conclusion, the immunological responses to bulk and particulate biomaterials vary greatly depending on the implant material types, the size of particulate and its volume, and where the response to bulk forms of differing biomaterials are relatively acute and similar, while wear particles can initiate a variety of responses such as osteolysis, metal sensitivity, and so on.

Characterization of wear debris from metal-on-metal hip implants during normal wear versus edge-loading conditions

Advantages of second-generation metal-on-metal (MoM) hip implants include low volumetric wear rates and the release of nanosized wear particles that are chemically inert and readily cleared from local tissue. In some patients, edge loading conditions occur, which result in higher volumetric wear. The objective of this study was to characterize the size, morphology, and chemistry of wear particles released from MoM hip implants during normal (40° angle) and edge-loading (65° angle with microseparation) conditions. The mean primary particle size by volume under normal wear was 35 nm (range: 9-152 nm) compared with 95 nm (range: 6-573 nm) under edge-loading conditions. Hydrodynamic diameter analysis by volume showed that particles from normal wear were in the nano- (<100 nm) to submicron (<1000 nm) size range, whereas edge-loading conditions generated particles that ranged from <100 nm up to 3000-6000 nm in size. Particles isolated from normal wear were primarily chromium (98.5%) and round to oval in shape. Edge-loading conditions generated more elongated particles (4.5%) (aspect ratio ≥ 2.5) and more CoCr alloy particles (9.3%) compared with normal wear conditions (1.3% CoCr particles). By total mass, edge-loading particles contained approximately 640-fold more cobalt than normal wear particles. Our findings suggest that high wear conditions are a potential risk factor for adverse local tissue effects in MoM patients who experience edge loading. This study is the first to characterize both the physical and chemical characteristics of MoM wear particles collected under normal and edge-loading conditions. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 986-996, 2018.

Cementless Total Hip Arthroplasty With Metasul Bearings Provides Good Results in Active Young Patients: A Concise Followup

BACKGROUND

A primary concern of younger, more active patients who have undergone total hip arthroplasty (THA) is the longevity of the implant. Cementless fixation and hard-on-hard bearings are recognized as options to enhance THA durability. Earlier, we published a series of 83 cementless primary THAs using 28-mm metal-on-metal (MoM) bearings in patients aged 50 years or younger; here we provide concise followup on that same group after an additional 8-year survey period.

QUESTIONS/PURPOSES

(1) What is the long-term survivorship of cementless primary THA using 28-mm MoM bearings in patients aged 50 years or younger? (2) What are the clinical and radiographic results of cementless THA in this active patient population? (3) Can any of the observed implant failures or adverse events be attributed to the metallic nature of the bearing couple?

METHODS

We retrospectively reviewed 83 cementless THAs performed in three institutions over a decade (1995-2004) in 68 patients with 28-mm MoM articulation. All patients (15 bilateral) had a median age of 42 years (range, 24-50 years) at the time of the index procedure and 56 of them (82% [70 hips]) had activity level graded Devane 4 or 5 before significant hip pain. A 28-mm Metasul™ articulation was used with an Alloclassic-SL™ cementless stem in all cases paired with three different cementless titanium acetabular components (one threaded and two press-fit cups) from the same manufacturer. Survivorship analysis was calculated according to Dobbs life table, patient clinical results were evaluated with use of the Postel-Merle d'Aubigné scoring system, radiographic analysis was performed by independent observers, and cobalt level was determined in whole blood.

RESULTS

The 15-year survivorship (33 hips at risk) for revision for any reasons (four hips) and for aseptic loosening (one hip) was 96% (95% confidence interval [CI], 81%-99%) and 99% (95% CI, 85%-99.9%), respectively. The median Merle d'Aubigné-Postel score remained stable at 17 points (range, 10-18). Thus far, we have not observed pseudotumors or other adverse reactions to metallic debris. Eight hips have undergone reoperation: trochanteric suture removal (one), psoas tendon impingement (two), and five revisions for periprosthetic fracture (one), late infection (two), acetabular osteolysis (one, as a result of polyethylene backside wear), and one hydroxyapatite-coated cup for aseptic loosening. None of the complications, failures, or revisions observed so far could directly be related to the metallic nature of the 28-mm Metasul bearings used in this selected group of patients.

CONCLUSIONS

The current survey at 13-year median followup has not yet indicated any long-term deleterious effects related to dissemination of metallic ions. Two senior authors continue to use 28- or 32-mm Metasul™ bearings with cementless THA components in young and active patient populations. Longer followup with a more sophisticated imaging study is necessary to confirm this so far positive report.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Co-Cr dental alloys induces cytotoxicity and inflammatory responses via activation of Nrf2/antioxidant signaling pathways in human gingival fibroblasts and osteoblasts

OBJECTIVE

Although cobalt-chromium (Co-Cr) dental alloys are routinely used in prosthodontics, the biocompatibility of Co-Cr alloys is controversial. The aims of the present study were to investigate the effects of Co-Cr alloys on human gingival fibroblasts (HGF) and osteoblasts in an in vitro model as well as their potential molecular mechanisms, focusing on NF-E2-related factor 2 (Nrf2) pathways.

METHODS

Cells were directly seeded on prepared Co-Cr alloy discs (15.0mm diameter, 1.0mm thickness) or indirectly treated with Co-Cr alloy located at the bottom of an insert well and incubated for 3 days. Cytotoxicity and reactive oxygen species (ROS) production was evaluated by MTS assay and flow cytometry, respectively. Protein and mRNA levels were determined by Western blotting and RT-PCR analysis, respectively.

RESULTS

Cell viability and flow cytometric assay demonstrated that the Co-Cr alloy was cytotoxic to HGFs and osteoblasts, and significantly increased ROS production. In addition, the Co-Cr alloys upregulated pro-inflamamtory cytokines (TNF-α, IL-1β, IL-6, and IL-8) and increased levels of various inflammatory mediators (iNOS derived nitrite oxide, and COX-2-derived PGE2) in both cells. A mechanistic study showed that Co-Cr alloys activates the NRF2 pathway and up-regulate antioxidant enzymes including heme oxygenase-1 (HO-1). Co-Cr alloys activated JAK2/STAT3, p38/ERK/JNK MAPKs and NF-κB signaling pathways. Furthermore, antioxidants (resveratrol and NAC) and HO-1 inhibitor (SnPP) significantly inhibited the production of ROS and inflammatory mediators, as well as the activation of NF-κB signaling in Co-Cr alloy stimulated HGFs and osteoblasts.

SIGNIFICANCE

This study is the first to show that Co-Cr alloys exert cytotoxic and inflammatory effects via activation of Nrf2/ARE signaling and up-regulation of downstream HO-1, which could represent candidate targets for the regulation of inflammatory responses to Co-Cr alloys.

Crowe Type I and II DDH managed by large diameter metal-on-metal total hip arthroplasty

Large bearing metal-on-metal (MOM) total hip arthroplasty (THA) may offer advantages relating to stability and range of motion in patients with Crowe Type I and II developmental dysplasia of the hip (DDH). The purpose of this study was to provide an analysis of the clinical and radiological results of MOM THA in this context and compare the results with a cohort of patients treated with metal-on-polyethylene (MOP) bearing surfaces. 75 hips in 65 patients were treated with cementless MOM THA using large femoral heads (36-56 mm). The mean age of the patients was 47.4 years (29 to 59) and 54 were female. A group of 47 hips (41 patients) treated with conventional THA (screwed cup-polyethylene insert-28 mm head) was used for comparison. The study group was followed up for a mean of 62.1 months (32 to 76). No difference was found between the two groups in relation to improvement in Harris hip score (HHS) (43.1 to 90.3 points in the study group, 42.6 to 89.5 points in the control group, p>0.05). Although the preoperative range of motion in all planes were similar in both groups, the large head group demonstrated greater motion in all planes postoperatively, which was significant (all p=0.001). Additionally, there was a significant difference between groups in relation to the necessity for acetabular structural graft (8% and 31.9%, respectively; p=0.001). No major complications or adverse reactions to metal debris (ARMD) were observed in the study group. The results of large head MOM THA in young and active patients with DDH are similar to conventional THA at early follow-up, but the former offers the advantages of secure acetabular fixation without screws, greater range of motion, and lower risk of dislocation.

MicroRNA-mediated immune modulation as a therapeutic strategy in host-implant integration

The concept of implanting an artificial device into the human body was once the preserve of science fiction, yet this approach is now often used to replace lost or damaged biological structures in human patients. However, assimilation of medical devices into host tissues is a complex process, and successful implant integration into patients is far from certain. The body's immediate response to a foreign object is immune-mediated reaction, hence there has been extensive research into biomaterials that can reduce or even ablate anti-implant immune responses. There have also been attempts to embed or coat anti-inflammatory drugs and pro-regulatory molecules onto medical devices with the aim of preventing implant rejection by the host. In this review, we summarize the key immune mediators of medical implant reaction, and we evaluate the potential of microRNAs to regulate these processes to promote wound healing, and prolong host-implant integration.

Practical considerations for volumetric wear analysis of explanted hip arthroplasties

OBJECTIVES

Wear debris released from bearing surfaces has been shown to provoke negative immune responses in the recipient. Excessive wear has been linked to early failure of prostheses. Analysis using coordinate measuring machines (CMMs) can provide estimates of total volumetric material loss of explanted prostheses and can help to understand device failure. The accuracy of volumetric testing has been debated, with some investigators stating that only protocols involving hundreds of thousands of measurement points are sufficient. We looked to examine this assumption and to apply the findings to the clinical arena.

METHODS

We examined the effects on the calculated material loss from a ceramic femoral head when different CMM scanning parameters were used. Calculated wear volumes were compared with gold standard gravimetric tests in a blinded study.

RESULTS

Various scanning parameters including point pitch, maximum point to point distance, the number of scanning contours or the total number of points had no clinically relevant effect on volumetric wear calculations. Gravimetric testing showed that material loss can be calculated to provide clinically relevant degrees of accuracy.

CONCLUSIONS

Prosthetic surfaces can be analysed accurately and rapidly with currently available technologies. Given these results, we believe that routine analysis of explanted hip components would be a feasible and logical extension to National Joint Registries. Cite this article: Bone Joint Res 2014;3:60-8.

Metal-on-Metal Hip Retrieval Analysis: A Case Report

This is a case report involving a single case with severe bone and soft tissue destruction in a young male patient with a 10-year-metal on-metal total hip arthroplasty. Following complete aseptic erosion of the affected hip greater trochanter and abductor muscles, the hip was revised for recurrent instability. Histological examination of the patient's periprosthetic tissues, serological studies, and review of recent medical reports of similar cases were used to support an explanation of the destructive process and better contribute to our understanding of human reaction to metal debris in some patients following metal-on-metal hip arthroplasty.

MR imaging of metal-on-metal hip prostheses

Metal-on-metal (MoM) hip arthroplasty was expected to provide benefits over metal-on-polyethylene systems. After widespread placement of MoM implants, outcomes have been disappointing. MoM implants are associated with higher serum levels of metal ions, adverse periarticular soft tissue reactions, and increased long-term failure rates. In light of these findings, it is crucial that patients with MoM implants be closely monitored for adverse effects. MR imaging is ideally suited for assessment of these patients and complements standard clinical evaluation and laboratory testing. This article reviews the background of MoM implants, emerging data on complications, strategies for using MR imaging, and MR imaging findings in patients with reaction to metal.

CoCrMo metal-on-metal hip replacements

After the rapid growth in the use of CoCrMo metal-on-metal hip replacements since the second generation was introduced circa 1990, metal-on-metal hip replacements have experienced a sharp decline in the last two years due to biocompatibility issues related to wear and corrosion products. Despite some excellent clinical results, the release of wear and corrosion debris and the adverse response of local tissues have been of great concern. There are many unknowns regarding how CoCrMo metal bearings interact with the human body. This perspective article is intended to outline some recent progresses in understanding wear and corrosion of metal-on-metal hip replacement both in vivo and in vitro. The materials, mechanical deformation, corrosion, wear-assisted corrosion, and wear products will be discussed. Possible adverse health effects caused by wear products will be briefly addressed, as well as some of the many open questions such as the detailed chemistry of corrosion, tribochemical reactions and the formation of graphitic layers. Nowadays we design almost routinely for high performance materials and lubricants for automobiles; humans are at least as important. It is worth remembering that a hip implant is often the difference between walking and leading a relatively normal life, and a wheelchair.

If hip implant retrievals could speak, what would they tell us?

Hip implant retrieval analysis is the most important source of insight into the performance of new materials and designs of hip arthroplasties. Even the most rigorous in vitro testing will not accurately simulate the behavior of implant materials and new designs of prosthetic arthroplasties. Retrieval analysis has revealed such factors as the effects of gamma-in-air sterilisation of polyethylene, fatigue failure mechanisms of polymethylmethacrylate bone cement, fretting corrosion of Morse taper junctions, third body wear effects of both hard-on-hard and hard-on-soft bearing couples, and the effects of impingement of components on the full spectrum of bearing surfaces, none of which was predicted by pre-implantation in vitro testing of these materials and combinations. The temporal sequence of the retrieval process is approximately six years from first implantation through retrieval analysis, laboratory investigation, and publication of results, and thus, in addition to rigorous clinical evaluation, represents the true development and insight cycle for new designs and materials.

Successful long-term fixation and progression of osteolysis associated with first-generation cementless acetabular components retrieved post mortem

BACKGROUND

Primary cementless acetabular reconstruction has shown durable long-term fixation. Late failures secondary to aseptic loosening are rare but may occur in patients with previously well-fixed components. In the present study, the histopathological characteristics of postmortem specimens were correlated with wear damage and radiographic data in an attempt to better understand the long-term events in the periacetabular tissue around well-functioning devices.

METHODS

Seventeen primary cementless Harris-Galante I acetabular components with adjacent tissues were harvested after a mean of eleven years (range, four to twenty-five years) from patients whose implants were well functioning at the time of death. Undecalcified and paraffin sections were used to quantify the extent of bone and soft tissues within the porous coating and at the interface between the coating and the surrounding bone. Wear particles were identified with use of polarized light microscopy and energy-dispersive x-ray analysis. Bearing-surface volumetric wear and backside wear damage of the polyethylene liner were assessed.

RESULTS

All of the components were fixed by bone ingrowth (mean extent, 33% ± 21%). Particle-induced granulomas were present in the porous coating and along the interface and progressed through screw holes, ballooning into the retroacetabular bone in the longer-term specimens. Particles of femoral and acetabular origin were identified in the granulomas. Bearing-surface volumetric wear (mean, 41.6 mm3/year) increased with duration and correlated with increasing extent of granuloma in the porous coating and the increasing size of pelvic granulomas. Radiolucencies on radiographs correlated with the extent of bone and fibrous tissue ingrowth. Of the six pelvic granulomas that were identified histologically, only one was apparent on routine radiographs.

CONCLUSIONS

Acetabular fixation by bone ingrowth can be successful into the third decade after implantation. Osteolysis and secondary replacement of bone with particle-induced granuloma are commonly seen in the presence of excellent clinical function. Strategies designed to minimize bearing-surface wear and backside damage are important to maintain long-term bone ingrowth fixation.

Minocycline-induced periarticular black bones in inflamed joints which underwent arthroplastic reconstruction

Background

Minocycline-induced pigmentation of bone (black bone) is well described in tooth-bearing intra-oral bone, but is less known in periarticular bone in patients who have undergone total joint arthroplasty. On a retrospective basis, we investigated the short-term clinico-radiological results of total joint arthroplasties in which the patient developed minocycline-induced periarticular black bone.

Methods

We found 5 cases (0.08%), in 4 patients, of periarticular bone pigmentation revealed during total joint arthroplasties (2 hips, 2 knees, and 1 ankle) in our series of total joint surgeries (6,548 cases) over a 10-year time period in our 3 institutes. Their mean age was 56 years at surgery. All patients had received long-term minocycline treatment. Mean dosage and duration of minocycline was 160 mg/day and 2.2 years, respectively. Minocycline had been prescribed for reactive arthritis (one), rheumatoid arthritis (two) and late infection after total joint arthroplasty (two patients). Mean follow-up period was 3.4 years after the surgeries.

Results

All cases had black or brown pigmentation in the periarticular bones during the surgery. There was no pigmentation in the cartilage or soft tissues of the joints. The mean Japanese Orthopaedic Association (JOA) score or Japanese Society for Surgery of the Foot (JSSF) scale for rheumatoid arthritis foot and ankle joints at latest follow-up (case 1, 66; case 2, 87; case 3, 77; case 4, 77; case 5, 80) improved compared to those of pre-surgery (case 1, 47; case 2, 45; case 3, 55; case 4, 34; case 5, 55). No implant loosening was noted on radiographic examination during the follow-up period. No abnormal bone formation, bone necrosis, hemosiderin deposition, malignancy or metallic debris was found on histological examination.

Conclusions

No clinico-radiological symptoms of total joint arthroplasties showed in the patients with minocycline-induced periariticular black bone in the short-term. Systemic minocycline treatment has the potential to induce significant black pigmentation of many tissues. In particular, minocycline-induced pigmentation of periarticular bone may be accelerated by inflammation due to rheumatic or pyogenic arthritis. Surgeons should recognize the risk of bone pigmentation in inflamed joints due to the systemic treatment of minocycline and explore its influence on periarticular bone and total joint arthroplasty in the long-term.

Femoral stem fracture and in vivo corrosion of retrieved modular femoral hips

A series of 78 retrieved modular hip devices were assessed for fretting and corrosion. Damage was common at both the head-neck junction (54% showing corrosion; 88% showing fretting) and at the stem-sleeve junction (88% corrosion; 65% fretting). Corrosion correlated to in vivo duration, patient activity, and metal (vs ceramic) femoral heads but did not correlate to head carbon content. Femoral stem fatigue fracture was observed in seven retrievals; all had severe corrosion, were under increased stress, and were in vivo longer than the non-fractured cohort. This study emphasizes the potential for stem fracture when small diameter femoral stems with large offsets are used in heavy and active patients. Designs which reduce fretting and corrosion in modular implants is warranted as patients demand longer lasting implants.

Accelerating failure rate of the ASR total hip replacement

There is widespread concern regarding the incidence of adverse soft-tissue reactions after metal-on-metal (MoM) hip replacement. Recent National Joint Registry data have shown clear differences in the rates of failure of different designs of hip resurfacing. Our aim was to update the failure rates related to metal debris for the Articular Surface Replacement (ASR). A total of 505 of these were implanted. Kaplan-Meier analysis showed a failure rate of 25% at six years for the ASR resurfacing and of 48.8% for the ASR total hip replacement (THR). Of 257 patients with a minimum follow-up of two years, 67 (26.1%) had a serum cobalt concentration which was greater than 7 μg/l. Co-ordinate measuring machine analysis of revised components showed that all patients suffering adverse tissue reactions in the resurfacing group had abnormal wear of the bearing surfaces. Six THR patients had relatively low rates of articular wear, but were found to have considerable damage at the trunion-taper interface. Our results suggest that wear at the modular junction is an important factor in the development of adverse tissue reactions after implantation of a large-diameter MoM THR.

Mediators of the inflammatory response to joint replacement devices

Joint replacement surgery is one of the success stories of modern medicine, restoring mobility, diminishing pain and improving the overall quality of life for millions of people. Unfortunately, wear of these prostheses over time generates debris, which activates an innate immune response that can ultimately lead to periprosthetic resorption of bone (osteolysis) and failure of the implant. Over the past decade, the biological interactions between the particulate debris from various implant materials and the immune system have begun to be better understood. The wear debris induces a multifaceted immune response encompassing the generation of reactive oxygen species and damage-associated molecular patterns, Toll-like receptor signaling and NALP3 inflammasome activation. Acting alone or in concert, these events generate chronic inflammation, periprosthetic bone loss and decreased osteointegration that ultimately leads to implant failure.

Cementless metal-on-metal versus ceramic-on-polyethylene hip arthroplasty in patients less than fifty years of age: a comparative study with twelve to fourteen-year follow-up

BACKGROUND

We previously reported the outcomes of a case-control study, at a minimum of five years of follow-up, comparing metal-on-metal and ceramic-on-polyethylene bearings for cementless primary hip arthroplasty in active patients below the age of fifty years. This report is an update on these groups after a minimum duration of follow-up of twelve years.

METHODS

Thirty-nine metal-on-metal cementless hip replacements with a 28-mm-diameter Metasul articulation were compared with a control group that included thirty-nine cementless ceramic-on-polyethylene hip replacements performed with a 28-mm-diameter head. The Metasul group included thirty patients with a mean age of forty years (range, twenty-three to forty-nine years), and the control group included thirty-two patients with a mean age of forty-one years (range, fifteen to forty-nine years). The groups were matched for age, activity level, preoperative Harris hip score, acetabular cup diameter, and indication for hip arthroplasty. All patients had a high level of activity, with 82% rated as grade IV or V according to the Devane scale.

RESULTS

After a mean duration of follow-up of thirteen years (twelve to fourteen years), only one hip (3%) had asymptomatic acetabular osteolysis and no hip (0%) had been revised in the metal-on-metal group, whereas eighteen hips (46%) had osteolysis and eleven hips (28%) had been revised because of wear or osteolysis in the ceramic-on-polyethylene group (p < 0.003). In the metal-on-metal group, the median Co concentration in the whole blood was 0.95 μg/L (0.4 to 4.8 μg/L) and the median Cr concentration was 1.2 μg/L (0.1 to 5.6 μg/L). The twelve-year survival rate (with reoperation for any reason as the end point) was 100% in the metal-on-metal group and 70% (95% confidence interval, 63% to 77%) in the ceramic-on-polyethylene group (p = 0.003).

CONCLUSIONS

After twelve to fourteen years of follow-up, metal-on-metal implants demonstrated better radiographic and survival results than ceramic-on-polyethylene implants in young, very active patients. Current wrought metal-on-metal implants with a 28-mm-diameter head and high carbide concentration did not produce the high rates of osteolysis and allergic reactions that may be observed with cast low-carbide metal-on-metal bearings after a shorter duration of follow-up.