A minimum 5-year follow-up of an oxidized zirconium femoral prosthesis used for total knee arthroplasty

Fe and C additions decrease the dissolution rate of silicon nitride coatings and are compatible with microglial viability in 3D collagen hydrogels

Silicon nitride (SiN) coatings may reduce unwanted release of metal ions from metallic implants. However, as SiN slowly dissolves in aqueous solutions, additives that reduce this dissolution rate would likely increase the lifetime and functionality of implants. Adding iron (Fe) and carbon (C) permits tuning of the SiN coatings' mechanical properties, but their effect on SiN dissolution rates, and their capacity to reduce metal ion release from metallic implant substrates, have yet to be investigated. Such coatings have recently been proposed for use in spinal implants; therefore, it is relevant to assess their impact on the viability of cells expected at the implant site, such as microglia, the resident macrophages of the central nervous system (CNS). To study the effects of Fe and C on the dissolution rate of SiN coatings, compositional gradients of Si, Fe and C in combination with N were generated by physical vapor deposition onto CoCrMo discs. Differences in composition did not affect the surface roughness or the release of Si, Fe or Co ions (the latter from the CoCrMo substrate). Adding Fe and C reduced ion release compared to a SiN reference coating, which was attributed to altered reactivity due to an increase in the fraction of stabilizing Si-C or Fe-C bonds. Extracts from the SiN coatings containing Fe and C were compatible with microglial viability in 2D cultures and 3D collagen hydrogels, to a similar degree as CoCrMo and SiN coated CoCrMo reference extracts. As Fe and C reduced the dissolution rate of SiN-coatings and did not compromise microglial viability, the capacity of these additives to extend the lifetime and functionality of SiN-coated metallic implants warrants further investigation.

Beneficial effect of a zirconium-nitride-coated implant in total knee arthroplasty revision for suspected metal hypersensitivity

INTRODUCTION

Revision of total knee arthroplasty (rTKA) for suspicion of metal hypersensitivity (MHS) may require hypoallergenic implants. Results for coated implants have not been reported. The aim of the present study was to assess short-term results and survival of rTKA for MHS using a multilayer implant coating.

HYPOTHESIS

Multilayer implant coating improves functional results in rTKA, with survival comparable to primary coated implants.

MATERIAL AND METHODS

A single-center retrospective observational study included 28 patients (30 knees) undergoing rTKA for MHS using a coated implant between May 2011 and November 2016. Exclusion criteria comprised implant malpositioning and history of infection in the affected knee. Clinical and radiological results were assessed on the International Knee Society (IKS) and SF-36 functional scores and Ewald radiological score. Survival was calculated on Kaplan-Meier estimation.

RESULTS

Mean follow-up was 3.8 years. Mean IKS score increased by 40.2 points (40%) [range, 28.1-52.3] (p<0.05). Mean range of motion increased by 17° [range, 9.5-24.5°] (p<0.05). Mean physical and mental SF-36 components were respectively 44.7 and 46.1. Survivorship was 93%.

DISCUSSION

There was significant functional improvement after rTKA for MHS. There were no short-term complications related to the zirconium nitrate coating. However, studies with longer follow-up will be needed for confirmation.

LEVEL OF EVIDENCE

IV; retrospective study.

Tailoring the dissolution rate and in vitro cell response of silicon nitride coatings through combinatorial sputtering with chromium and niobium

Ceramic coatings have been widely investigated as a means to reduce wear and metallic ion release from joint implants. Silicon nitride-based coatings have been a topic of interest specifically due to their solubility in aqueous solutions. This could imply a reduced adverse immune response since the generated debris would dissolve. However, there are concerns regarding the dissolution rate and adhesion of these silicon nitride-based coatings. This study attempts to address the concern of dissolution rate as well as coating adhesion of silicon nitride coatings. We hypothesized that alloying with chromium and niobium would affect the adhesion, dissolution rate, and the resulting ion release and cell response to the coatings. A combinatorial approach was used to deposit sputtered coatings with compositional gradients both with and without a CrN interlayer. Compositional gradients were achieved for all the investigated elements: Si (38.6-46.9 at%), Nb (2.2-4.6 at%) and Cr (1.9-6.0 at%). However, while the presence of an interlayer reduced the delamination during adhesion testing, the differences in composition in the top coating did not affect the adhesion. Nor did the top coating's composition affect the surface roughness or the coatings' inherent mechanical properties (elastic modulus and hardness). All coating compositions were associated with a low Co release from the underlying metal and points with a higher Cr content (4.3-6.0 at%) gave an overall lower release of Si, Cr and Nb ions, possibly due to the formation of a stable oxide, which reduced the dissolution rate of the coating. Optimum chromium contents were furthermore found to give an enhanced in vitro fibroblast cell viability. In conclusion, the results indicate a possibility to tailor the ion release rate, which lends promise to further investigations such as tribocorrosive tests towards a future biomedical application.

Metal Hypersensitivity and Complex Regional Pain Syndrome After Bilateral Total Knee Arthroplasty: A Case Report

CASE

A 38-year-old man underwent bilateral total knee arthroplasty (TKA) and subsequently developed diffuse pain, swelling, and an eczematous rash that spread throughout his body. Despite various pharmacological regimens, sympathetic blocks, aggressive physical therapy, and further knee revisions, the patient's symptoms progressed over a period of 2 years. An in vitro memory lymphocyte immuno-stimulation assay test demonstrated reactivity to nickel after which bilateral revision TKAs with oxidized zirconium alloys resulted in symptomatic improvement.

CONCLUSION

Metal hypersensitivity should be considered after the exclusion of infection; however, the concurrent development of complex regional pain syndrome may mask the clinical presentation.

Oxidized Zirconium Components Maintain a Smooth Articular Surface Except Following Hip Dislocation

BACKGROUND

Oxidized zirconium (OxZr) offers theoretical advantages in total hip and knee arthroplasty (THA and TKA, respectively) relative to other biomaterials by combining the tribological benefits of ceramics with the fracture toughness of metals. Yet, some studies have found that OxZr does not improve outcomes or wear rates relative to traditional bearing materials such as cobalt-chromium (CoCr). Separately, effacement of the thin ceramic surface layer has been reported for OxZr components, though the prevalence and sequelae are unclear.

METHODS

To elucidate the in vivo behavior of OxZr implants, the articular surfaces of 94 retrieved THA and TKA femoral components (43 OxZr TKA, 21 OxZr THA, 30 CoCr THA) were analyzed using optical microscopy, non-contact profilometry, and scanning electron microscopy.

RESULTS

We found that OxZr components maintain a smooth articular surface except following hip dislocation. Three of four OxZr femoral heads revised following dislocation exhibited severe damage to the articular surface, including macroscopic regions of ceramic-layer effacement and exposure of the underlying metal substrate; these components were 23-32 times rougher than pristine OxZr controls. When revised for dislocation, OxZr femoral heads were substantially rougher than CoCr femoral heads (median S_a = 0.431 v. 0.020 μm, P = .03). In contrast, CoCr femoral heads exhibited low overall roughness values regardless of whether they dislocated (median S_a = 0.020 v. 0.008 μm, P = .09, CoCr dislocators v. non-dislocators).

CONCLUSIONS

Effacement of the ceramic surface layer and substantial articular surface roughening is not atypical following dislocation of OxZr femoral heads, making OxZr much less tolerant than CoCr to hip dislocation.

The effect of patient-reported metal allergies on the outcomes of shoulder arthroplasty

BACKGROUND

Although literature exists regarding hip and knee arthroplasty outcomes in patients with skin allergy to metals, there is minimal information about skin allergy implications on shoulder arthroplasty outcomes. The purpose of this study was to determine the results, complications, and failure rate among patients with a self-reported metal allergy undergoing shoulder arthroplasty.

METHODS

Fifty-two shoulder arthroplasties were performed at our Institution in 43 patients with self-reported metal allergies. Forty primary and 12 revision shoulder arthroplasties were performed using anatomic (30) and reverse (22) components. Retrospective chart review was performed to determine metal allergy history, implant composition, pain, motion, and complications. Radiographs were reviewed to determine mechanical failure rates. Average follow-up time was 65 months.

RESULTS

Allergies reported included nickel (37), cobalt chrome (4), copper (2), zinc (1), titanium (1), gold (1), and nonspecific metal allergy (8); 8 patients reported multiple metal allergies. All components implanted in patients with nickel allergies contained nickel. At most recent follow-up, pain was rated as none or mild in 88% of shoulders. Active elevation improved from 80° to 141° and external rotation from 24° to 52°. Two revisions were performed for glenoid loosening (3.8%); both were revision cases with substantial glenoid bone loss. One patient with mild pain had a radiographically loose glenoid component 12 years after anatomic shoulder arthroplasty.

CONCLUSION

Results from this study suggest that shoulder arthroplasty in patients with self-reported metal allergy provides satisfactory pain relief and improved range of motion with low revision rates.

Does oxidized zirconium make a difference? Midterm cohort survivorship of symmetric posterior condyle posterior-stabilized total knee arthroplasty

Background

A novel symmetric posterior condylar design and option of a femoral component with an outer zirconium oxide layer were introduced to a successful asymmetric condylar total knee arthroplasty system in 2005. Given the paucity of information on this modified design, we performed a study to determine its early to midterm survivorship and performance.

Methods

Patients who received the Genesis II Symmetric Posterior Condyle or Legion Primary total knee (cobalt–chromium [CoCr] or oxidized zirconium–niobium [OxZr]) (Smith & Nephew) implanted at the study centre between March 2007 and December 2013 were enrolled into a prospective database. We retrospectively reviewed the database and performed survival analysis using Kaplan–Meier techniques.

Results

There were 2178 patients (1359 women [62.4%]; mean age 64.6 yr; mean body mass index 35.0) with 2815 knee replacements available for analysis. Survival rates were 98.2% (95% confidence interval [CI] 97.6%–98.7%) for failure for any reason at 2 years and 96.8% (95% CI 96.0%–97.7%) at 5 years. Age (hazard ratio [HR] 0.97, 95% CI 0.94–0.997) and female sex (HR 0.45, 95% CI 0.27–0.75) were protective, whereas body mass index (HR 1.02, 95% CI 0.99–1.05) and OxZr implant (HR 1.11, 95% CI 0.57–2.18) did not influence survivorship. Oxford Knee Score values improved from a mean of 40.2 to 21.8 by 2 years (p < 0.001), with no difference between the CoCr and OxZr groups.

Conclusion

The symmetric posterior condylar posterior-stabilized knee offers excellent midterm survivorship. Implant bearing surface did not have an influence on survivorship to 5 years, and, thus, use of OxZr implants may not be justified.

A 13- to 16-year clinical and radiological outcome study of the genesis II cruciate retaining total knee arthroplasty with an oxidised zirconium femoral component

PURPOSE

The Genesis II Total Knee Arthroplasty with an oxidized zirconium (OxiniumTM) femoral component (Smith & Nephew, Memphis, TN, USA) was introduced in an attempt to reduce polyethylene wear and osteolysis.

METHODS

We retrospectively evaluated prospectively collected data from 245 consecutive patients (40 men and 205 women; mean age at surgery 70.1 years, range 44 to 85 years) who underwent 261 TKAs with a mean follow-up of 15.1 years (range 13 to 16 years). Implant failure rate, complication rate, clinical (both subjective and objective) and radiological outcomes were assessed.

RESULTS

At final follow-up, 24 (9.8 %) patients (24 TKAs) were lost to follow-up and 35 (14.3%) patients (35 TKAs) had died for reasons unrelated to surgery. Four TKAs, in four patients, were revised because of aseptic loosening. In five TKAs (five patients) secondary patella resurfacing was performed because of patellofemoral pain. Survivorship analysis showed a cumulative success rate of 98.4% (95% CI, 94.3% - 100%) at 15 years with revision for aseptic loosening as an end point, and 95.6% (95% CI, 92.7% - 98.7%) at 15 years with revision for any reason as an end point. All patients showed a statistically significant improvement (p = 0.01) in the Knee Society clinical rating system, WOMAC Score, KOOS Score, Oxford Knee Score and EuroQol 5D Score. Surgery fulfilled patient expectations for 90.1% of patients; in 5.4% it did not, and 4.5% declined to answer.

CONCLUSION

This study demonstrates satisfactory long-term clinical results for this knee design.

Allergy in total knee replacement surgery: Is it a real problem?

Total knee arthroplasty is a common procedure, with extremely good clinical results. Despite this success, it produces 20% unsatisfactory results. Among the causes of these failures is metal hypersensitivity. Metal sensitization is higher in patients with a knee arthroplasty than in the general population and is even higher in patients undergoing revision surgery. However, a clear correlation between metal sensitization and symptomatic knee after surgery has not been ascertained. Surely, patients with a clear history of metal allergy must be carefully examined through dermatological and laboratory testing before surgery. There is no globally accepted diagnostic algorithm or laboratory test to diagnose metal hypersensitivity or metal reactions. The patch test is the most common test to determine metal hypersensitivity, though presenting some limitations. Several laboratory assays have been developed, with a higher sensitivity compared to patch testing, yet their clinical availability is not widespread, due to high costs and technical complexity. Symptoms of a reaction to metal implants present across a wide spectrum, ranging from pain and cutaneous dermatitis to aseptic loosening of the arthroplasty. However, although cutaneous and systemic hypersensitivity reactions to metals have arisen, thereby increasing concern after joint arthroplasties, allergies against implant materials remain quite rare and not a well-known problem. The aim of the following paper is to provide an overview on diagnosis and management of metal hypersensitivity in patients who undergo a total knee arthroplasty in order clarify its real importance.

The 2018 Mark Coventry, MD Award: Does a Ceramic Bearing Improve Pain, Function, Wear, or Survivorship of TKA in Patients Younger Than 55 Years of Age? A Randomized Trial

BACKGROUND

Methods to reduce the revision rate of total knee prostheses because of wear-related issues are important to examine, particularly because younger patients have a disproportionately high risk of revision.

QUESTIONS/PURPOSES

(1) Are long-term Knee Society knee and function scores better in younger patients with an oxidized zirconium (OxZr) TKA compared with those with a cobalt-chrome (CoCr) TKA? (2) Are there differences in radiographic signs of loosening or CT findings of osteolysis between OxZr TKAs and CoCr TKAs? (3) Are there fewer polyethylene wear particles in the OxZr TKA than CoCr TKA? (4) Do the groups differ in terms of survivorship free from revision surgery at 13 years?

METHODS

From April 2003 to January 2007, we enrolled 110 patients younger than 55 years of age in this randomized, double-blind, prospective trial. Each patient served as his or her own control and each received an OxZr femoral component in one knee and a CoCr femoral component in the other. The minimum followup was 10 years (mean, 13 years; range, 10-14 years); two died and nine were lost to followup before that time, leaving 99 patients (198 knees) for analysis. There were 28 men and 71 women with a mean age of 53 ± 6 years (range, 40-55 years). We obtained Knee Society knee scores for each knee, but Knee Society function scores, WOMAC scores, and UCLA activity scores were obtained for each patient preoperatively and at each followup. Additionally, we performed radiographic examination preoperatively and at each followup. At a minimum of 10 years (mean, 13 years) followup, we obtained CT scans in all patients. Polyethylene wear particles in the synovial fluid were analyzed at the final followup using thermogravimetric methods and scanning electron microscopy. Survivorship was ascertained using the Kaplan-Meier calculator. A sample size calculation determined that to detect a difference in the Knee Society knee score of 5 points, assuming a SD of 5 points, with an α = 0.05 and β = 0.80, a total of 90 patients would be needed in each group.

RESULTS

At the most recent followup, the mean Knee Society knee scores (92 versus 93 points; p = 0.857), function scores (85 versus 85 points; p = 1.000), WOMAC scores (23 versus 23 points; p = 1.000), UCLA activity scores (6.5 versus 6.5 points; p = 1.000), and range of knee motion (125° versus 127°; p = 0.365) were not different between the two groups. There was no radiographic evidence of loosening and no osteolysis visible on CT scan in either group. The weight of polyethylene wear particles produced at the bearing surface was 0.046 ± 0.010 g in 1 g of synovial fluid in patients with an OxZr femoral component and 0.0448 ± 0.0108 g in patients with a CoCr femoral component (p = 0.583). Kaplan-Meier survivorship free from revision was 97% for the OxZr group (95% confidence interval [CI], 93-100) and 98% for the CoCr group (95% CI, 93-100) at 13 years after surgery (p = 0.918).

CONCLUSIONS

Given the absence of demonstrated superiority of either the CoCr implant or the OxZr implant, we recommend that surgeons and healthcare systems can reasonably choose the less expensive device for routine use, unless there is some compelling reason in an individual patient to choose one over the other (such as severe, documented metal sensitivity).

LEVEL OF EVIDENCE

Level I, therapeutic study.

A comparative surface topographical analysis of explanted total knee replacement prostheses: Oxidised zirconium vs cobalt chromium femoral components

It has been proposed that an increased surface roughness of the femoral components of Total Knee Replacements (TKRs) may be a contributing factor to the accelerated wear of the polyethylene (PE) bearing and ultimately prosthesis failure. Oxidised Zirconium was introduced to the orthopaedic market in an attempt to reduce PE wear associated failures and increase the longevity of the prosthesis. In this study, non-contacting profilometry was used to measure the surface roughness of the femoral components of 6 retrieved TKRs (3 Oxidised Zirconium (OxZr) and 3 Cobalt Chromium alloy (CoCr) femoral components) and 2 as-manufactured femoral components (1 OxZr and 1 CoCr). A semi-quantitative method was used to analyse the damage on the retrieved PE components. The S_a values for the retrieved OxZr femoral components (S_a = 0.093 µm ± 0.014) and for the retrieved CoCr femoral components (S_a = 0.065 µm ± 0.005) were significantly greater (p < .05) than the roughness values for the as-manufactured femoral components (OxZr S_a = 0.061 µm ± 0.004 and CoCr S_a = 0.042 µm ± 0.003). No significant difference was seen between the surface roughness parameters of the retrieved OxZr and retrieved CoCr femoral components. There was no difference between the PE component damage scores for the retrieved OxZr TKRs compared to the retrieved CoCr TKRs. These results agree with other studies that both OxZr and CoCr femoral components roughen during time in vivo but the lack of difference between the surface roughness measurements of the two materials is in contrast to previous topographical reports. Further analysis of retrieved OxZr TKRs is recommended so that a fuller appreciation of their benefits and limitations be obtained.

Oxidized zirconium versus cobalt-chromium against the native patella in total knee arthroplasty: Patellofemoral outcomes

BACKGROUND

Oxidized zirconium (OxZr) has demonstrated excellent mechanical properties in vitro when used against articular cartilage; less coefficient of friction and less chondral damage have been found when compared with cobalt-chromium (CoCr) implants. However, controversy exists as to whether implants with a zirconium femoral component articulate safely with a native patella in total knee arthroplasty (TKA). To answer this question, the clinical and radiographic results were analysed from a group of patients who underwent a TKA with patella retention; the OxZr versus CoCr femoral components were compared.

METHODS

The present study prospectively evaluated 83 knees of 74 patients from 2009 to 2010. Each patient was evaluated clinically (visual analogue scale, Knee Society score, patellar score) and radiographically (long leg standing radiograph, anterior-posterior and latero-lateral projections, axial view of the patella) pre-operatively and postoperatively with a mean follow-up of 4.47years. The patellar tilt and shift, and progression of patellofemoral osteoarthritis were calculated with the axial view.

RESULTS

There were no patient reported adverse reactions and none of the evaluated prostheses failed. Both the clinical and radiographic evaluations showed no statistically significant between-group differences.

CONCLUSION

No adverse events were observed clinically or radiologically. These results justify pursuing the use of oxidized zirconium as an alternative bearing surface for a femoral component associated with patellar retention in TKA.

Twelve-Year Outcomes of an Oxinium Total Knee Replacement Compared with the Same Cobalt-Chromium Design: An Analysis of 17,577 Prostheses from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

Oxidized zirconium (Oxinium) was introduced as an alternative bearing surface to cobalt-chromium (CoCr) in an attempt to reduce polyethylene wear and decrease aseptic mechanical failure of total knee replacements. While noncomparative reports have been described as promising, we were aware of no short or long-term clinical studies showing the superiority of Oxinium on polyethylene as a bearing surface. Using data from a comprehensive national joint replacement registry, we compared the long-term outcomes after cruciate-retaining total knee arthroplasty (TKA) with an Oxinium femoral component and those with the same prosthetic design but with a CoCr femoral component.

METHODS

The cohorts consisted of 17,577 cemented Genesis-II cruciate-retaining total knee replacements using non-cross-linked polyethylene, which included 11,608 with CoCr femoral components and 5,969 with Oxinium femoral components. The cumulative percent revision and hazard ratio (HR) for revision risk were estimated for the cemented Genesis-II Oxinium and CoCr cruciate-retaining TKAs performed in Australia from September 1, 1999, to December 31, 2013. In addition, the revision diagnoses and the effects of age and patellar resurfacing were examined.

RESULTS

No difference in the HR for revision risk was found between the Oxinium and CoCr cohorts for any age category for all causes of revision (HR = 0.92 [95% confidence interval (CI), 0.92 to 1.29]; p = 0.329), loosening or lysis, or aseptic causes, except for loosening or lysis in the group of patients who were ≥75 years old (p = 0.033). In these patients, TKA with Oxinium femoral components had a higher rate of revision. Younger patients preferentially received Oxinium femoral components. The revision risk was not affected by patellar resurfacing or nonresurfacing. At 12 years, the cumulative percent revision was 4.8% (95% CI, 4.2% to 5.4%) for the CoCr Genesis-II prosthesis compared with 7.7% (95% CI, 6.2% to 9.5%) for the Oxinium Genesis-II prosthesis.

CONCLUSIONS

In this cohort study involving the same prosthetic design, Oxinium femoral components did not reduce revision rates for all causes, loosening or lysis, or when infection as a cause of revision was removed compared with the same CoCr femoral component across all age groups including patients who were <55 years old. The cumulative percent revision was greater for the Oxinium components than for the CoCr components.

LEVEL OF EVIDENCE

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

The Survival of Total Knee Arthroplasty: Current Data from Registries on Tribology: Review Article

BACKGROUND

Polyethylene (PE) wear is a major contributor to implant loosening following total knee arthroplasty (TKA), and advanced bearings in TKA are being investigated with hopes of reducing or eliminate wear-related loosening. Currently, information on knee tribology is available from national joint registries and may be the best tools to evaluate the efficacy and safety of design innovations in joint arthroplasty.

QUESTIONS/PURPOSES

We performed a review of national joint registries trying to answer the following questions: "Which is the main factor directly related to revisions rate in TKA?" and "Are there new bearing options better than conventional ones?"

METHODS

A review was performed of all published annual reports of National Joint Registers, as well as of the literature. The search was carried out using and comparing the National Joint Registers.

RESULTS

Current data from registries for total knee arthroplasty indicates that age is the major factor affecting the outcome of primary total knee replacement. The 10-year cumulative revision rate for non-cross-linked PE was 5.8% and for XLPE it was 3.5%. The effect of cross-linked polyethylene was more evident in the younger patients. The survival of the oxidized zirconium (OxZr) femoral component appears better when compared to a similar age group of patients with conventional group of prostheses. Our review suggests that the revision rates are half for the OxZr components compared to conventional CoCr femoral components.

CONCLUSIONS

Age is the most relevant single factor related to revision rate. Cross-linked PE has a statistical lower revision rate at 10 years compared to conventional PE and, in the OxZr group, the revision rate is 2 times lower than Co-Cr in the same group of age.

Allergy in Total Knee Replacement. Does It Exist?: Review Article

BACKGROUND

There is little data on whether preexisting allergies to implant materials and bone cement have an impact on the outcome of TKA.

QUESTIONS/PURPOSES

This review article analyzes the current literature to evaluate the prevalence and importance of metal and cement allergies for patients undergoing total knee arthroplasty.

METHODS

A review of the literature was performed using the following search criteria: "knee," "arthroplasty," and "allergy" as well as "knee," "arthroplasty," and "hypersensitivity."

RESULTS

One hundred sixteen articles were identified on PubMed, Seventy articles could be excluded by reviewing the title and abstract leaving 46 articles to be included for this review. The majority of the studies cited patch testing as the gold standard for screening and diagnosis of hypersensitivity following TKA. There is consensus that patients with self-reported allergies against metals or bone cement and positive patch test should be treated with hypoallergenic materials or cementless TKA. Treatment options include the following: coated titanium or cobalt-chromium implants, ceramic, or zirconium oxide implants.

CONCLUSION

Allergies against implant materials and bone cement are rare. Patch testing is recommended for patients with self-reported allergies. The use of special implants is recommended for patients with a confirmed allergy.

Revision total knee arthroplasty due to bone cement and metal hypersensitivity

INTRODUCTION

Hypersensitivity to implants is a rare complication of total knee arthroplasty (TKA). Metal and, less frequently, bone cement can produce allergic symptomatology that if unresponsive to conservative treatment could lead to revision.

MATERIALS AND METHODS

We present the case of a patient with generalized pruritus and metal taste starting during the first postoperative month after TKA. Dermal allergy exams revealed that the patient had hypersensitivity to nickel sulphate and cobalt chloride and bone cement. Conservative treatment with antihistamine medication and corticosteroids failed to control the symptoms. The patient underwent revision TKA with a hypoallergic prosthesis 8 months after the primary procedure.

RESULTS

Full disappearance of the symptoms occurred 3 months after revision. The latest follow-up evaluation (3 years post-revision) was unremarkable.

CONCLUSIONS

In our opinion, an exhaustive medical history should be obtained from every candidate for total joint replacement and in cases of prior severe allergic reactions to metals, plastics or glues, patch testing of the components of the future prosthesis should be done. When an already implanted prosthesis causes symptoms like pain, edema, pruritus, erythema, limited range of motion and increase in joint's temperature, the possibility of allergy to metals and/or bone cement (in case of cemented prosthesis) should be checked after the exclusion of other reasons like infection. If symptoms cannot be controlled by conservative measures, revision should be decided and carried out with hypoallergic prosthesis.

Clinical Results of Oxidized Zirconium Femoral Component in TKA. A Review of Long-Term Survival: Review Article

BACKGROUND

Oxidized zirconium (OxZr) femoral component for total knee arthroplasty (TKA) have been introduced in an attempt to reduce polyethylene wear and secondary osteolysis and improve longevity of implants.

QUESTIONS/PURPOSES

We reviewed clinical studies in literature evaluating OxZr femoral component for TKA. The aim of this review was to evaluate the clinical outcome and survival rate of TKA with an OxZr femoral component.

METHODS

A review of the existing literature was undertaken to collect data on the OxZr femoral component in order to provide a better understanding of its performance. Of 34 studies published in the literature, 8 met the eligibility criteria and were included in the final analysis.

RESULTS

Findings indicated that the mean Knee Society knee score improved in all series from preoperative to postoperative evaluation. The postoperative Knee Society knee score reported range from 84 to 95 and mean postoperative Knee Society functional score range from 74 to 90. The revision rate with this implant is low with up to 12.6 years of follow-up, with three revisions in total. The survival rate ranged from 100-98.7% at 5-7 years to 97.8% at 10 years.

CONCLUSIONS

Excellent clinical outcome and high survival rate has been demonstrated for OxZr femoral component in TKA. No adverse reaction has been described for this new material.

The Journey patellofemoral joint arthroplasty: A minimum 5year follow-up study

BACKGROUND

The Journey patellofemoral joint arthroplasty (PFA) was designed to improve patient outcomes following surgical management of patellofemoral joint osteoarthritis. It is based on the asymmetric trochlear geometry of the Genesis II total knee arthroplasty, with Oxinium components, to provide a reliable treatment option in an often young, high demand group of patients.

METHODS

We report the minimum five year functional outcome and survivorship of the Journey PFA performed at our institution between October 2005 and September 2009.

RESULTS

A total of 101 Journey PFAs were implanted in 83 patients, and we have complete outcomes for 90 implants (89%). There were 80 implants in female patients, and the mean age at time of surgery was 60years (26 to 86). The median Oxford Knee Score (0 to 48) improved from 18 to 30, and median Western Ontario and McMaster University Osteoarthritis Short Form Index (0 to 60) improved from 22 to 35. There were a total of 12 revisions, with mean time to revision 50months (10 to 99).

CONCLUSIONS

The Journey PFA gives a good medium-term functional outcome with 88% survivorship at a mean of seven years. This is the largest study of Journey PFA in the literature, and it provides a reliable option for patients with isolated patellofemoral joint osteoarthritis when arthroplasty is considered.

No Increased Risk of Knee Arthroplasty Failure in Patients With Positive Skin Patch Testing for Metal Hypersensitivity: A Matched Cohort Study

BACKGROUND

It is unclear whether a positive skin patch test for metal allergy in patients with skin hypersensitivity to metals is associated with an increased risk of total knee arthroplasty (TKA) failure. Our aim was to determine whether patients with a history of metal allergy who had a positive skin patch test (SPT+) had worse outcomes after primary TKA compared with those with a negative skin patch test and compared with controls.

METHODS

Over 12 years, 127 patients underwent 161 TKA after skin patch testing (SPT; 56 were positive). Cases were matched by age, gender, body mass index, American Society of Anesthesiologists score, implant type, and implant manufacturer to 161 control knee arthroplasties without any prior history of metal allergy and no SPT. Median follow-up was 5.3 years. Differences in outcome measures were assessed between groups.

RESULTS

Patients with a SPT+ to metal did not have a higher complication, reoperation, or revision rates compared with patients with a SPT- and matched controls. Survivorship free of revision at 5 years was 98.1% for SPT+; 100% for SPT-; 97.6% for SPT+ controls, 99.0% for SPT- controls. There was no statistically significant difference in postoperative pain between SPT+ and SPT- patients and matched controls.

CONCLUSION

This study was designed to evaluate the effect of metal hypersensitivity on TKA outcomes and the role of SPT in patients before TKA. In this study, a SPT+ for metals was of little practical value in predicting the midterm outcome after TKA and cannot be strongly recommended as a method to guide the selection of implant type.

Fabrication and characterization of carboxymethyl cellulose novel microparticles for bone tissue engineering

In this study we developed carboxymethyl cellulose (CMC) microparticles through ionic crosslinking with the aqueous ion complex of zirconium (Zr) and further complexing with chitosan (CS) and determined the physio-chemical and biological properties of these novel microparticles. In order to assess the role of Zr, microparticles were prepared in 5% and 10% (w/v) zirconium tetrachloride solution. Scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS) results showed that Zr was uniformly distributed on the surface of the microparticles as a result of which uniform groovy surface was obtained. We found that Zr enhances the surface roughness of the microparticles and stability studies showed that it also increases the stability of microparticles in phosphate buffered saline. The crosslinking of anionic CMC with cationic Zr and CS was confirmed by Fourier transform infrared spectroscopy (FTIR) results. The response of murine pre-osteoblasts (OB-6) when cultured with microparticles was investigated. Live/dead cell assay showed that microparticles did not induce any cytotoxic effects as cells were attaching and proliferating on the well plate as well as along the surface of microparticles. In addition, SEM images showed that microparticles support the attachment of cells and they appeared to be directly interacting with the surface of microparticle. Within 10days of culture most of the top surface of microparticles was covered with a layer of cells indicating that they were proliferating well throughout the surface of microparticles. We observed that Zr enhances the cell attachment and proliferation as more cells were present on microparticles with 10% Zr. These promising results show the potential applications of CMC-Zr microparticles in bone tissue engineering.

Total knee arthroplasty with an oxidised zirconium femoral component: ten-year survivorship analysis

AIMS

Oxidised zirconium was introduced as a material for femoral components in total knee arthroplasty (TKA) as an attempt to reduce polyethylene wear. However, the long-term survival of this component is not known.

METHODS

We performed a retrospective review of a prospectively collected database to assess the ten year survival and clinical and radiological outcomes of an oxidised zirconium total knee arthroplasty with the Genesis II prosthesis. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS) and a patient satisfaction scale were used to assess outcome.

RESULTS

A total of 303 consecutive TKAs were performed in 278 patients with a mean age of 68 years (45 to 89). The rate of survival ten years post-operatively as assessed using Kaplan-Meier analysis was 97% (95% confidence interval 94 to 99) with revision for any reason as the endpoint. There were no revisions for loosening, osteolysis or failure of the implant. There was a significant improvement in all components of the WOMAC score at final follow-up (p < 0.001). The mean individual components of the KOOS score for symptoms (82.4 points; 36 to 100), pain (87.5 points; 6 to 100), activities of daily life (84.9 points; 15 to 100) and quality of life (71.4 points; 6 to 100) were all at higher end of the scale.

DISCUSSION

This study provides further supportive evidence that the oxidised zirconium TKA gives comparable rates of survival with other implants and excellent functional outcomes ten years post-operatively.

TAKE HOME MESSAGE

Total knee arthroplasty with an oxidised zirconium femoral component gives comparable long-term rates of survival and functional outcomes with conventional implants.

In Vivo Wear Performance of Cobalt-Chromium Versus Oxidized Zirconium Femoral Total Knee Replacements

This study examines the damage and wear on the polyethylene (PE) inserts from 52 retrieved Genesis II total knee replacements to identify differences in tribological performance between matched pairs of cobalt-chromium (CoCr) and oxidized zirconium (OxZr) femoral components. Observer damage scoring and microcomputed tomography were used to quantify PE damage and wear, respectively. No significant differences were found between CoCr and OxZr groups in terms of PE insert damage, surface penetration, or wear. No severe damage such as cracking or delamination was noted on any of the 52 PE inserts. Observer damage scoring did not correlate with penetrative or volumetric PE wear. The more costly OxZr femoral component does not demonstrate clear tribological benefit over the standard CoCr component in the short term with this total knee replacement design.

Prospective multi-centre study on a composite ceramic femoral component in total knee arthroplasty: Five-year clinical and radiological outcomes

BACKGROUND

Enhanced wear resistance of ceramics in general and improved mechanical characteristics of composite ceramics in terms of strength and resistance meet the demands for application in TKA. The aim of this prospective international multi-centre study was to evaluate the 5-year clinical and radiological outcomes of an unconstrained TKA with a composite ceramic femoral component.

METHODS

A total of 107 patients (109 knees) underwent TKA with the MULTIGEN-PLUS Ceramic Knee at seven centres in three European countries. Clinical and radiological assessments were performed preoperatively and postoperatively at 3, 12, 24 and 60 months, using HSS, WOMAC, SF-36 and standardised radiographs.

RESULTS

Mean HSS and WOMAC increased significantly from 55.1±11.5 (21-83) and 48.1±16.6 (3-90) preoperatively to 85.6±9.6 (49-98) and 73.3±20.4 (17-100) at 60 months. Mean SF-36 showed significant improvements in patients' quality of life (49.1±17.6 (12-96) preoperatively versus 67.7±23.1 (12-100) at 60 months). Non-progressive radiolucent lines (<1 mm) were observed around the femoral component in four cases. Neither implant migration nor loosening were registered. Kaplan-Meier survivorship was 96.0% at 60 months (92.1-100%, CI 95%).

CONCLUSIONS

Five-year implant survival rate of the ceramic knee is comparable to other metallic and ceramic unconstrained TKA systems. Although the assessment of long-term implant survivorship is still pending, the ceramic implants represent a promising solution for patients with allergies against metallic components and furthermore for the general osteoarthritis population due to enhanced wear resistance.

Articulating Biomaterials

This chapter examines the importance of surface characteristics such as microstructure, composition, crystallographic texture, and surface free energy in achieving desired biocompatibility and tribological properties thereby improving in vivo life of artificial articulating implants. Current implants often fail prematurely due to inadequate mechanical, tribological, biocompatibility, and osseointegration properties, apart from issues related to design and surgical procedures. For long-term in vivo stability, artificial implants intended for articulating joint replacement must exhibit long-term stable articulation surface without stimulating undesirable in vivo effects. Since the implant's surface plays a vital and decisive role in their response to biological environment, and vice versa, surface modification of implants assumes a significant importance. Therefore, overview on important surface modification techniques, their capabilities, properties of modified surfaces/implants are presented in the chapter. The clinical performance of surface modified implants and new surfaces for potential next-generation articulating implant applications are discussed at the end.