Chyun-Yu Yang

Tourniquet use in total knee arthroplasty: a meta-analysis

PurposeThe use of an intraoperative tourniquet for total knee arthroplasty (TKA) is a common practice. However, the effectiveness and safety are still questionable. A systematic review was conducted to examine that whether using a tourniquet in TKA was effective without increasing the risk of complications.MethodsA comprehensive literature search was done in PubMed Medicine, Embase, and other internet database. The review work and the following meta-analysis were processed to evaluate the role of tourniquet in TKA.ResultsEight randomized controlled trials and three high-quality prospective studies involving 634 knees and comparing TKA with and without the use of a tourniquet were included in this analysis. The results demonstrated that using a tourniquet could decrease the measured blood loss but could not decrease the calculated blood loss, which indicated actual blood loss. Patients managed with a tourniquet might have higher risks of thromboembolic complications. Using the tourniquet with late release after wound closure could shorten the operation time; whereas early release did not show this benefit.ConclusionsThe current evidence suggested that using tourniquet in TKA may save time but may not reduce the blood loss. Due to the higher risks of thromboembolic complications, we should use a tourniquet in TKA with caution.

The influences of plasma spraying parameters on the characteristics of hydroxyapatite coatings: a quantitative study

All laboratory-made plasma-sprayed hydroxylapatite coatings (HACs) were found to undergo, to different degrees, changes in phase composition, crystallinity, morphology and roughness dependent on plasma spraying parameters (PSPs). The PSPs, which were systematically varied, included the plasma atmosphere, the spraying current and the stand-off distance. Through the determinations of the concentration of impurity phase (CIP) and the index of crystallinity (IOC), the extent of phase purity and the degree of crystallinity of HACs were quantitatively assessed, respectively. Coatings consisting of at least 50% (IOC>50%) of the original crystalline structure and almostly 95% (CIP<5%) apatite with barely detectable extra phases were obtained. The microstructure of HACs exhibited great deviations both in morphology from molten to partial molten state and in roughness from coating of high irregularity (Ra=14.48μm) to a smoother (Ra=4.46 μm) one, dominantly influenced by the spraying atmosphere. As the terms of CIP and IOC are defined and established, the biological responses related to phase purity and crystallinity of HACs can be further evaluated in vitro and in vivo.

Failure of hydroxyapatite-coated acetabular cups

Between March 1990 and May 1991 we performed 85 primary total hip replacements in 74 patients using the Landos Atoll hydroxyapatite (HA)-coated cup and the Corail HA-coated stem. The patients were followed up for a mean of ten years. Of the 85 cups, 26 (31%) have already been revised and a further six are radiologically unstable and awaiting revision. Two femoral stems have been revised for infection without loosening. The retrieved acetabular cups were studied by SEM and image-processing techniques to quantify the amount of residual HA on the cup. This was correlated with the clinical variables and modes of failure. The residual HA (as a percentage of the surface) on the loose cups correlated negatively with the duration of implantation (r = -0.732, p < 0.001). Six cups were stable at revision and had more residual HA coating than those which were loose (p < 0.01). The rate of failure of the Landos Atoll HA-coated, smooth hemispherical cup with screw fixation is unacceptably high. Resorption of the HA coating is markedly increased in loose cups compared with stable cups. HA coating cannot substitute for stable mechanical fixation.

Effects of tourniquet use on blood loss and soft-tissue damage in total knee arthroplasty: a randomized controlled trial.

BACKGROUND Although tourniquets are widely used in total knee arthroplasty, their effectiveness in reducing blood loss and their influence on the postoperative course remain unclear. Tourniquet-related soft-tissue damage is a related concern. We performed a prospective, randomized, controlled trial to clarify the effect of tourniquets in total knee arthroplasty. METHODS Seventy-two patients undergoing total knee arthroplasty were randomly allocated to a tourniquet or non-tourniquet group. Blood loss and changes in C-reactive protein, creatine phosphokinase, and other indicators of soft-tissue damage were monitored preoperatively and postoperatively on Days 1, 2, and 4. Thigh pain, knee pain, limb swelling, rehabilitation progress, and hospital stays were also recorded for comparison. RESULTS Patients in the tourniquet group showed smaller decreases in hemoglobin (mean and standard deviation, 2.6 ± 0.9 versus 3.7 ± 1.3 g/dL) and hematocrit (7.6% ± 2.8% versus 10.4% ± 4.0%), less calculated blood loss (303 ± 119 versus 423 ± 197 mL), and smaller increases in C-reactive protein (peak value, 175 ± 55 versus 139 ± 75 mg/dL) and creatine phosphokinase (peak value, 214 ± 89 versus 162 ± 104 U/L) compared with those in the non-tourniquet group. There was slightly less postoperative pain in the non-tourniquet group. There were no significant differences between the groups in terms of swelling, rehabilitation progress, or hospital stays. CONCLUSIONS The use of a tourniquet during total knee arthroplasty was effective for reducing blood loss and avoiding excessive postoperative inflammation and muscle damage. The use of a tourniquet was related to slightly more postoperative pain but did not affect postoperative recovery.

In vitro and in vivo mechanical evaluations of plasma-sprayed hydroxyapatite coatings on titanium implants: The effect of coating characteristics

This study was undertaken to evaluate the effect of coating characteristics on the mechanical strengths of the plasma-sprayed HA-coated Ti-6Al-4V implant system both in vitro and in vivo. Two types of HA coatings (HACs) with quite different microstructures, concentrations of impurity-phases, and indices-of-crystallinity were used. In vitro testings were done by measuring the bonding-strength at the Ti-6Al-4V-HAC interface, with HACs that had and had not been immersed in a pH-buffered, serum-added simulated body fluid (SBF). The shear-strength at the HAC-bone interface was investigated in a canine transcortical femoral model after 12 and 24 weeks of implantation. The results showed a bonding degradation of approximately 32% or higher of the original strength after 4 weeks of immersion in SBF, and this predominantly depended on the constructed microstructure of the HACs. After the push-out measurements, it was demonstrated that the HACs with higher bonding-strength in vitro would correspondingly result in significantly higher shear-strength at each implant period in vivo. Nevertheless, there were no substantial histological variations between the two types of HACs evaluated. The most important point elucidated in this study was that, among coating characteristics, the microstructure was the key factor in influencing the mechanical stability of the HACs both in vitro and in vivo. As a consequence, a denser HAC was needed to ensure mechanical stability at both interfaces.

Bond degradation at the plasma-sprayed HA coating/Ti-6AI-4V alloy interface: an in vitro study

The successful use of the plasma-sprayed HA-coated Ti-6AI-4V system requires strong adhesion between the ceramic coating and the underlying metal substrate. The aim of this study was to evaluate the bond strength at the HA coating (HAC)/Ti-6AI-4V interface, for specimens that had and had not been subjected to immersion in a pH-buffered, serum-added simulated body fluid (SBF). Moreover, coating characteristics affecting the mechanical stability after having been immersed in SBF were clarified. The results showed that bonding degradation of approximately 25–33% of the original strength was measured after immersion in SBF, and that this predominantly depended on the characteristics of the HAC and the period of immersion. Since the surface morphologies of HACs have dissolved in the SBF, it is suggested that the interlamellar structure of the HAC was weakened and, therefore, the bond strength degraded. As both the crystallinity and impurity phases of the HAC increased with immersion time, it can be concluded that the dissolution of the HAC resulting from the initial microstructure has overtaken that of the coating crystallinity and phase purity. A denser microstructure is required to ensure a satisfactory HAC/Ti-6AI-4V interface.

Two-stage cementless revision THR after infection. 5 recurrences in 40 cases followed 2.5-7 years

We revised 40 infected hip prostheses in 40 patients as a two-stage procedure, including intravenous and oral antibiotics, gentamicin beads, and delayed cementless implantation of porous-coated THR. The duration of antibiotic treatment was 8 weeks. The interval from resection to reimplantation was, on average, 48 (8-108) weeks. 39 patients were followed, on average, 4 (2.5-7) years. 5 patients had a recurrent infection. In patients who did not have a recurrent infection, the Harris hip score exceeded 80 in 32 patients. Radiographically, femoral component migration of 2-6 mm was noted in 3 cases. The recurrent infection rate, and the functional and radiographic results are comparable with those obtained using a two-stage procedure with antibiotic cement.

Characteristics and osteoconductivity of three different plasma-sprayed hydroxyapatite coatings

Abstract Plasma-sprayed hydroxyapatite coating (HAC) on a bioinert metal substrate was used clinically to increase the fixation of an orthopaedic implant. This study aimed to clarify in vitro various characteristics of plasma-sprayed HACs, and to evaluate in vivo the effect of coating characteristics on the osteoconductivity of HACs. Three different HACs on Ti-6A1-4V substrate were prepared by varying the plasma spraying parameters; these were then characterized in detail. Subsequently, in the cortex of canine femur, a quantitative histologic evaluation was performed. This was done to determine the osteoconductivity of HACs, represented as the new bone healing index (NBHI), after 2, 4, 6, and 12 weeks of implantation. The results in vitro demonstrated that the microstructure, phase composition, crystallinity, OH-ion content, and calcium to phosphorus molar ratio of the HACs varied with the spraying parameters. The HAC with denser microstructure and less thickness showed a higher bonding strength at the HAC-Ti-6A1-4V interface. However, this denser HAC underwent adverse biological degration in terms of NBHI after 12 weeks of implantation because of other characteristics of the coating. Based on the results of the study, it can be concluded that an HAC with both high bonding strength and good osteoconductivity is difficult to acheive.

Arthrodesis with a short Huckstep nail as a salvage procedure for failed total knee arthroplasty.

Arthrodesis of the knee with use of a short Huckstep nail was performed in thirty-three patients (thirty-three knees) after failure of a non-constrained total knee arthroplasty. The indication for the arthrodesis was an infection in thirty-one knees and a Charcot joint in two. Three knees had had a failed attempt at arthrodesis with use of external fixation. The Huckstep nail was inserted through the knee, retrograde into the femur, and then antegrade into the tibia. The duration of the operation averaged 104 minutes (range, sixty-five to 155 minutes). Local bone graft was used in all knees. At the time of follow-up, at an average of forty-seven months (range, eighteen to ninety-four months), thirty knees (91 per cent) had radiographic evidence of union. The average time to union was 5.2 months (range, two to ten months) after the arthrodesis. Eight knees that had a grossly purulent infection were treated with débridement, which was followed by the arthrodesis as a second-stage procedure; the other knees had a one-stage arthrodesis. Only one of the thirty-one knees that had had an infection before the arthrodesis had a recurrence after it. Arthrodesis with a short Huckstep nail provides immediate axial and rotational stability and allows weight-bearing without use of external support as well as placement of the knee in a slightly flexed and valgus position. In addition, the nail does not migrate and it may be used even when there is a standard-size prosthesis in the ipsilateral hip.

Attachment and proliferation of neonatal rat calvarial osteoblasts on Ti6Al4V: effect of surface chemistries of the alloy.

This study examined the cell attachment and proliferation of neonatal rat calvarial osteoblasts on Ti6Al4V alloy as affected by the surface modifications. The modifications could alter simultaneously the surface chemistries of the alloy (elemental difference of Ti, Al, V, Cu and Ni about 300-600mum thick examined by EDS) as well as the XPS nano-surface characteristics of oxides on the metal surface (chemistries of oxides, amphoteric OH group adsorbed on oxides, and oxide thickness). Three materials including two from modifications and a control were examined. It is argued that a slight change of the nano-surface characteristics of oxides as a result of the modifications neither alters the in vitro capability of Ca and P ion adsorption nor affects the metal ion dissolution behavior of the alloy. This implies that any influence on the cytocompatibility of the materials should only be correlated to the effect of surface chemistries of the alloy and the associated metal ion dissolution behavior of the alloy. The experimental results suggest that the cell response of neonatal rat calvarial osteoblasts on the Ti6Al4V alloy should neither be affected by the variation of surface chemistries of the alloy in a range studied.