Dataset Information

Hydroxyapatite (HA) coating appears to be of benefit for implant durability of tibial components in primary total knee arthroplasty.

ABSTRACT:

Background

It is unclear whether there is a clinical benefit to adding hydroxyapatite (HA) coatings to total knee implants, especially with the tibial component, where failure of the implant more often occurs. A systematic review of the literature was undertaken to identify all prospective randomized trials for determining whether the overall clinical results (as a function of durability, function, and adverse events) favored HA-coated tibial components.

Methods

A comprehensive literature search was performed for the years 1990 to September 16, 2010. We restricted our search to randomized controlled trials involving participants receiving either an HA-coated tibia or other forms of tibial fixation. The primary outcome measures evaluated were durability, function, and acute adverse events.

Results

Data from 926 evaluable primary total knee implants in 14 studies were analyzed. Using an RSA definition for durability, HA-coated tibial components (porous or press-fit) without screw fixation were less likely to be unstable at 2 years than porous and cemented metal-backed tibial components (RR = 0.58, 95% CI: 0.34-0.98; p = 0.04, I(2) = 39%, M-H random effects model). There was no significant difference in durability, as measured from revision and evaluated at 2 and 8-10 years, between groups. Also, functional status using different validated measures showed no significant difference at 2 and 5 years, no matter what measure was used. Lastly, there was no significant difference in adverse events. Limitations included small numbers of evaluable patients (? 50) in 7 of the 14 trials identified, and a lack of "hard" evidence of durability with need for replacement (i.e. frank failure, pain, or loss of functionality).

Interpretation

In patients > 65 years of age, an HA-coated tibial implant may provide better durability than other forms of tibial fixation. Larger trials should be undertaken comparing the long-term durability, function, and adverse events of HA-coated implants with those of other porous-coated tibial implants in younger, more active OA patients.

SUBMITTER: Voigt JD

PROVIDER: S-EPMC3237036 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

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Publications

Hydroxyapatite (HA) coating appears to be of benefit for implant durability of tibial components in primary total knee arthroplasty.

Voigt Jeffrey D JD Mosier Michael M

Acta orthopaedica 20110610 4

<h4>Background</h4>It is unclear whether there is a clinical benefit to adding hydroxyapatite (HA) coatings to total knee implants, especially with the tibial component, where failure of the implant more often occurs. A systematic review of the literature was undertaken to identify all prospective randomized trials for determining whether the overall clinical results (as a function of durability, function, and adverse events) favored HA-coated tibial components.<h4>Methods</h4>A comprehensive li ...[more]

PMID: 21657975

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Project description:IntroductionRevision total knee arthoplasty often requires modular implants to treat bone defects of varying severity. In some cases, it may not be clear which module size and implant combination (e.g. sleeve and stem) should be chosen for a specific defect. When balancing implant stability and osseointegration against stress-shielding, it is important to choose an appropriate implant combination in order to match the given level of bone loss. Therefore, the necessity of stems in less extensive tibial defects and the advantage of different stems (lengths and stiffnesses) in combination with large metaphyseal sleeves on implant fixation and bone flexibility using a modular tibial revision knee system, were analyzed.Materials and methodsFour different stem combinations for a tibial revision implant (Sigma TC3, DePuy) were compared to an intact bone. Standardized implantation with n = 4 synthetic tibial bones was performed after generating an Anderson Orthopaedic Research Institute (AORI) Type T1 bone defect. Axial torques around the longitudinal stem axis and varus-valgus torques were separately applied to the implant. Micromotions of bone and implant were tracked using a digital image correlation system to calculate relative micromotions at the implant-bone-interface and bone deformation.ResultsOverall, using stems reduced the proximal micromotions of tray and sleeve compared to no stem, while reducing bone deformation proximally at the same time, indicating some potential for proximal stress-shielding compared to no stem. The potential for increased proximal stress-shield due to reduced proximal deformation appeared to be greater when using the longer stems. The location of lowest relative micromotions was also more distal when using long stems as opposed to short stems. A short stem (especially a smaller diameter short stem which still achieves diaphyseal fixation) displayed less potential for stress-shielding, but greater bone deformation distal to the tip of the stem than in the natural model.DiscussionIn the case of tibial revision implants with metaphyseal sleeves in a simple fully contained Type I defect, the absence of a stem provides for more natural bone deformation. However, adding a stem reduces overall relative micromotions, while introducing some risk of proximal stress-shielding due to increased diaphyseal fixation. Increasing stem length intensifies this effect. Short stems offered a balance between reduced micromotions and more proximal bone deformation that reduced the potential for stress-shielding when compared to long stems. A short stem with slightly smaller diameter (simulating a less stiff stem which still has diaphyseal fixation) increased the proximal bone deformation, but also tended to increase the bone deformation even further at the distal stem's tip.ConclusionIn conclusion, further investigation should be conducted on fully contained Type I defects and the addition of a stem to offer better initial stability, taking into account stem length (i.e. shorter or more flexible stems) to support metaphyseal fixation and allowing bending found in intact bone. In addition, further study into more extensive tibial defects is required to determine if the stability/micromotion trends observed in this study with stems and sleeves in Type I defects still apply in cases of extensive proximal bone loss.

Project description:Background and purposeIt is still being debated whether HA coating of uncemented stems used in total hip arthroplasty (THA) improves implant survival. We therefore investigated different uncemented stem brands, with and without HA coating, regarding early and long-term survival.Patients and methodsWe identified 152,410 THA procedures using uncemented stems that were performed between 1995 and 2011 and registered in the Nordic Arthroplasty Register Association (NARA) database. We excluded 19,446 procedures that used stem brands less than 500 times in each country, procedures performed due to diagnoses other than osteoarthritis or pediatric hip disease, and procedures with missing information on the type of coating. 22 stem brands remained (which were used in 116,069 procedures) for analysis of revision of any component. 79,192 procedures from Denmark, Norway, and Sweden were analyzed for the endpoint stem revision. Unadjusted survival rates were calculated according to Kaplan-Meier, and Cox proportional hazards models were fitted in order to calculate hazard ratios (HRs) for the risk of revision with 95% confidence intervals (CIs).ResultsUnadjusted 10-year survival with the endpoint revision of any component for any reason was 92.1% (CI: 91.8-92.4). Unadjusted 10-year survival with the endpoint stem revision due to aseptic loosening varied between the stem brands investigated and ranged from 96.7% (CI: 94.4-99.0) to 99.9% (CI: 99.6-100). Of the stem brands with the best survival, stems with and without HA coating were found. The presence of HA coating was not associated with statistically significant effects on the adjusted risk of stem revision due to aseptic loosening, with an HR of 0.8 (CI: 0.5-1.3; p = 0.4). The adjusted risk of revision due to infection was similar in the groups of THAs using HA-coated and non-HA-coated stems, with an HR of 0.9 (CI: 0.8-1.1; p = 0.6) for the presence of HA coating. The commonly used Bimetric stem (n = 25,329) was available both with and without HA coating, and the adjusted risk of stem revision due to aseptic loosening was similar for the 2 variants, with an HR of 0.9 (CI: 0.5-1.4; p = 0.5) for the HA-coated Bimetric stem.InterpretationUncemented HA-coated stems had similar results to those of uncemented stems with porous coating or rough sand-blasted stems. The use of HA coating on stems available both with and without this surface treatment had no clinically relevant effect on their outcome, and we thus question whether HA coating adds any value to well-functioning stem designs.

Project description:BackgroundPreviously, the authors modified the surgical technique to preserve tibial bone mass for Oxford unicompartmental knee arthroplasty (UKA). The purpose of this study was to determine the clinical outcomes and values of this modified technique.MethodsClinical data of 34 consecutive patients who underwent the unilateral modified UKA technique (modified group, 34 knees) were retrospectively analyzed. To compare the outcome, a match-paired control group (conventional group, 34 knees) of an equal number of patients using the conventional technique system in the same period were selected and matched with respect to diagnosis, age, pre-operative range of motion (ROM), and radiological grade of knee arthrosis. Clinical outcomes including knee Hospital for Special Surgery (HSS) score, ROM, and complications were compared between the two groups. Post-operative radiographic assessments included hip-knee-ankle angle (HKA), joint line change, implant position, and alignment.ResultsThe mean follow-up time was 38.2 ± 6.3 months. There was no difference in baseline between the two groups. The amount of proximal tibial bone cut in the modified group was significantly less than that of the conventional group (4.7 ± 1.1 mm vs. 6.7 ± 1.3 mm, t = 6.45, P < 0.001). Joint line was elevated by 2.1 ± 1.0 mm in the modified group compared with -0.5 ± 1.7 mm in the conventional group (t = -7.46, P < 0.001). No significant differences were observed between the two groups after UKA with respect to HSS score, VAS score, ROM, and HKA. Additionally, the accuracy of the post-operative implant position and alignment was similar in both groups. As for implant size, the tibial implant size in the modified group was larger than that in the conventional group (χ = 4.95, P = 0.035).ConclusionsThe modified technique for tibial bone sparing was comparable with the conventional technique in terms of clinical outcomes and radiographic assessments. It can preserve tibial bone mass and achieve a larger cement surface on the tibial side.

Dataset Information

Hydroxyapatite (HA) coating appears to be of benefit for implant durability of tibial components in primary total knee arthroplasty.

Background

Methods

Results

Interpretation

Publications

Hydroxyapatite (HA) coating appears to be of benefit for implant durability of tibial components in primary total knee arthroplasty.

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