Pablo Sanz-Ruiz

Evaluation of Elution and Mechanical Properties of High-Dose Antibiotic-Loaded Bone Cement: Comparative “In Vitro” Study of the Influence of Vancomycin and Cefazolin

Use of antibiotic-loaded bone cements is one of the most effective methods for the prevention and treatment of prosthetic joint infection. However, there is still controversy about the optimal combination and doses of antibiotics that provide the maximum antimicrobial effect without compromising cement properties. In this study, vancomycin and cefazolin were added to a bone cement (Palacos R+G). Antibiotic release, fluid absorption, and mechanical properties were evaluated under physiological conditions. The results show that the type of antibiotic selected has an important impact on cement properties. In this study, groups with cefazolin showed much higher elution than those containing the same concentration of vancomycin. In contrast, groups with cefazolin showed a lower strength than vancomycin groups.

Ultra–Minimally Invasive Ultrasound-Guided Carpal Tunnel Release A Randomized Clinical Trial

The purpose of this study was to compare the outcomes of 1‐mm ultra–minimally invasive ultrasound‐guided carpal tunnel release and 2‐cm blind mini–open carpal tunnel release.

Effects of Vancomycin, Cefazolin and Test Conditions on the Wear Behavior of Bone Cement

Antibiotic cement has been recommended in the treatment of prosthetic infections. The purpose of this study was to investigate the mechanical behavioral changes in cement loaded with two antibiotics, vancomycin and cefazolin, in dry and liquid medium. Six groups and four study conditions were established according to the doses of antibiotic used and the ageing (immersion in phosphate buffered saline) of the samples. Properties evaluated were friction coefficient and wear. Samples in dry medium showed higher wears than in liquid. Antibiotic selection did not influence wear properties tested in dry conditions, however, in liquid medium, there were higher frictional coefficients and wear for cefazolin loaded cement after one week and for vancomycin and cefazolin after one month. The results suggest that antibiotic cements behave differently in liquid and that the molecular characteristics of antibiotics are essential for determining this influence.

Does a new implant design with more physiological kinematics provide better results after knee arthroplasty

BACKGROUND Improved knee kinematics is one of the major goals to obtain better satisfaction after total knee arthroplasty. This study examined whether a guided motion knee design improves functional outcome and satisfaction as compared to a conventional design. METHODS In a retrospective manner, from January 2005 to December 2008, patients with two different kinematic TKA designs were enrolled. The 150 patients were divided into two groups: guided motion group (77) with kinematic design (Journey) and control group (73) with no kinematic design (LCS). All the patients had the same surgical technique and postoperative protocols. The functional and radiographic results were interpreted with the Hospital for Special Surgery (HSS) knee score and WOMAC score. RESULTS After a mean follow-up of 84.2months, the guided motion group had higher mean postoperative range of motion (p=0.022), functional status in the WOMAC function subscale (p=0.002), but had higher residual pain in the WOMAC pain subscale (p=0.018 and p=0.013) and higher iliotibial band syndrome incidence (6.6% vs 0%; p=0.02). There were no significant differences in HSS score between the two groups. No differences were seen between groups in patient satisfaction in the WOMAC total score (p=0.46) and survival rate. CONCLUSION The guided motion design can improve functional status according to WOMAC but not to HSS knee scores. Poorer pain scores and no higher patient satisfaction were observed with this kinematic design.

Patient-Specific Instrument Can Improve Functional and Radiographic Results during Learning Curve for Oxford Unicompartmental Knee Arthroplasty

Abstract The true value of use of patient‐specific instrumentation (PSI) systems by inexperienced surgeons during their learning curve to improve the clinical and radiographic outcome of unicompartmental knee arthroplasty (UKA) has not been previously studied. Fifty patients with a mean age of 64.3 years undergoing surgery for Oxford UKA were prospectively divided into two groups. Twenty‐five patients were operated on by a surgeon with no prior experience in UKA using a PSI system and the other 25 patients by an experienced surgeon using a conventional procedure. Patients were scored using joint range of motion (ROM), the Knee Society Score (KSS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the 12‐item Short‐Form (SF‐12) before and 3 months and 2 years after surgery. Impact of use of PSI was measured by comparing clinical and radiographic outcome, complications, and implant survival. No evidence of poorer clinical outcome was seen in any subscale of KSS, KOOS, and SF‐12 for inexperienced surgeons using PSI (p = 0.45, p = 0.32, and p = 0.61, respectively). No difference was found between the two procedures in precision of radiographic alignment of components (p = 0.53). No complication occurred in any group. PSI may improve precision of component alignment during the learning curve of surgeons, thus achieving functional results similar to those of more experienced surgeons using a conventional procedure.

Total femur arthroplasty for revision hip failure in osteogenesis imperfecta: limits of biology

Osteogenesis imperfecta (OI) is a rare congenital disease characterized by alterations in bone quality, with susceptibility to fractures, instability, deformities, and osteoarthrosis. Prosthetic surgery in these patients is associated with an abnormally high rate of implant failures. On the other hand, abnormal bone fragility adds to the complexity of revision surgery in such individuals—thus representing a genuine challenge for the orthopaedic surgeon. We present a case of femoral reconstruction in a patient with OI and prosthetic loosening after reconstruction secondary to femoral septic pseudoarthrosis. Intramedullary total femoral reconstruction was carried out after exceeding the biological reconstruction limits. This is the first reported instance of the use of an intramedullary total femur arthroplasty as salvage technique in an OI patient. This technique should be considered when we have exceeded biological limits for femoral fixation.

Revision TKA with a condylar constrained prosthesis using metaphyseal and surface cementation: a minimum 6-year follow-up analysis

BackgroundThe increasing number of revision knee arthroplasty result in the more frequently use of a constraint implant but results from previous reports are difficult to interpret. The purpose of this study was to compare the long-term outcomes of superficial cemented versus metaphyseal cemented in revision total knee arthroplasty with a condylar constrained arthroplasty.MethodsThe study was a retrospective analysis of clinical and radiographic outcomes in a series of revision total knee arthroplasties performed with a constrained condylar knee prosthesis and press-fit modular stems. We hypothesized that the clinical and radiographic outcome of surface cementation would be inferior to that of metaphyseal cementation. Fifty-two consecutive revision cases were followed for a median of 8.2 years (range, 6 to 10 years).ResultsSubstantial improvements in range of motion and Knee Society score were achieved in all patients, although these were not significant between groups. Significantly more radiolucent lines were visible on the tibial component with surface cementation than with metaphyseal cementation, although the clinical differences were not relevant.ConclusionsRadiologic outcome was better in revision total knee arthroplasty using metaphyseal cemented revision and components with press-fit cementless stems than in the surface cementation–based approach; however, the difference was not clinically relevant.

Nuevo método de liberación de antibióticos del cemento óseo (polimetilmetacrilato): redefiniendo los límites

INTRODUCTION The increasing antimicrobial resistance is promoting the addition of antibiotics with high antistaphylococcal activity to polymethylmethacrylate (PMMA), for use in cement spacers in periprosthetic joint infection. Linezolid and levofloxacin have already been used in in-vitro studies, however, rifampicin has been shown to have a deleterious effect on the mechanical properties of PMMA, because it inhibits PMMA polymerization. The objective of our study was to isolate the rifampicin during the polymerization process using microencapsulation techniques, in order to obtain a PMMA suitable for manufacturing bone cement spacers. MATERIAL AND METHOD Microcapsules of rifampicin were synthesized with alginate and PHBV, using Rifaldin®. The concentration levels of rifampicin were studied by UV-visible spectrophotometry. Compression, hardness and setting time tests were performed with CMW®1 cement samples alone, with non-encapsulated rifampicin and with alginate or PHBV microcapsules. RESULTS The production yield, efficiency and microencapsulation yield were greater with alginate (P = .0001). The cement with microcapsules demonstrated greater resistance to compression than the cement with rifampicin (91.26±5.13, 91.35±6.29 and 74.04±3.57 MPa in alginate, PHBV and rifampicin, respectively) (P = .0001). The setting time reduced, and the hardness curve of the cement with alginate microcapsules was similar to that of the control. DISCUSSION AND CONCLUSIONS Microencapsulation with alginate is an appropriate technique for introducing rifampicin into PMMA, preserving compression properties and setting time. This could allow intraoperative manufacturing of bone cement spacers that release rifampicin for the treatment of periprosthetic joint infection.

Microencapsulation of rifampicin: A technique to preserve the mechanical properties of bone cement: RIFAMPICIN-LOADED POLYMETHYLMETHACRYLATE

Two‐stage exchange with antibiotic‐loaded bone cement spacers remains the gold standard for chronic periprosthetic joint infection (PJI). Rifampicin is highly efficient on stationary‐phase staphylococci in biofilm; however, its addition to PMMA to manufacture spacers prevents polymerization and reduces mechanical properties. Isolation of rifampicin during polymerization by microencapsulation could allow manufacturing rifampicin‐loaded bone cement maintaining elution and mechanical properties. Microcapsules of rifampicin with alginate, polyhydroxybutyratehydroxyvalerate (PHBV), ethylcellulose and stearic acid (SA) were synthesized. Alginate and PHBV microcapsules were added to bone cement and elution, compression, bending, hardness, setting time and microbiological tests were performed. Repeated measures ANOVA and Bonferroni post‐hoc test were performed, considering a p < 0.05 as statistical significance. Bone cement specimens containing alginate microcapsules eluted more rifampicin than PHBV microcapsules or non‐encapsulated rifampicin over time (p < 0.012). Microencapsulation of rifampicin allowed PMMA to preserve mechanical properties in compression and bending tests. Cement with alginate microcapsules showed similar behavior in hardness tests to control cement over the study period (73 ± 1.68HD). PMMA with alginate microcapsules exhibited the largest zones of inhibition in microbiological tests. Statistically significant differences in mean diameters of zones of inhibition between PMMA loaded with alginate‐rifampicin (p = 0.0001) and alginate‐PHBV microcapsules (p = 0.0001) were detected. Rifampicin microencapsulation with alginate is the best choice to introduce rifampicin in PMMA preserving mechanical properties, setting time, elution, and antimicrobial properties. The main applicability of this study is the opportunity for obtaining rifampicin‐loaded PMMA by microencapsulation of rifampicin in alginate microparticles, achieving high doses of rifampicin in infected tissues, increasing the successful of PJI treatment.

Metallisation of Biolox Delta® Ceramic Head: What's Wrong?

Introduction Since the recent failure of certain coating models, hybrid implants (coated acetabular inserts with conventional stems) and stems with modular necks, there has been growing interest in the consequences of the generation and release of metal particles at the prosthetic interfaces. The use of ceramic heads has recently been described as an option for reducing the production of metal ions and their consequences. Case report The present case report describes the first complete metallisation of a ceramic head secondary to an excessive release of metal ions at the head-neck junction. Conclusions We believe this to have occurred due to the use of 12/14 cones of different manufacturers.