[Alloplastic Materials and their Propensity to Bacterial Colonisation]. / Aloplastické materiály z pohledu jejich citlivosti ke kolonizaci bakteriemi.

UNLABELLED: PURPOSE OF THE STUDY The alloplastic materials currently used for protective surface layers on implants were tested in vitro under microbiological laboratory conditions by contamination with microbial agents most frequently found in deep infection of total joint replacements. The objective was to find out how the resistance to bacterial colonisation was related to different surface finishes. MATERIAL AND METHODS Each of 14 samples of alloplastic material currently used in the manufacture of orthopaedic implants was inoculated with each of the group of microorganisms most frequently infecting joint replacements; these were Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli. At 24 hours of incubation, biofilms produced on sample surfaces were collected, stained with crystalline violet and assessed by spectrophotometry. The average value of biofilm absorbances (AV595) for the group of microorganism tested was taken as a basic characteristic of each material sample indicating its sensitivity to bacterial. RESULTS Of the metal materials with smooth surface finish, Vitalium (AV595, 0.368) showed the lowest affinity to microbial colonisation; next was titanium (AV595, 0.459) and steel (AV595, 0.505). A significant increase in sensitivity to bacterial colonisation was recorded in all types of surface finish of steel (AV595, 0.571) and in titanium alloy with a rough surface texture (AV595, 0.737 to 1.676); p < 0.05. Porous titanium surfaces significantly increased material affinity to colonisation. DISCUSSION Our study had certain limitations concerning in vitro evaluation of porous surfaces that have high affinity to bacterial colonisation. Porous titanium, and its hydroxyapatite layer in particular, considerably promotes osteoblast colonisation of the surface as well as implant osseointegration in the bone bed. Microorganisms therefore have no room for surface colonisation. Problematic may remain the surface parts outside contact with bone that keep their affinity to bacterial colonisation. CONCLUSIONS The material of choice for cemented implants is Vitalium which, of all metal surfaces, has the lowest sensitivity to bacterial colonisation. The materials of choice for cementless implants are titanium alloys. However, an osteoactive surface not in contact with bone remains a problem. On the one hand, its roughness and porosity are crucial to good osseointegration, on the other hand, its affinity to bacterial colonisation is high. KEY WORDS: alloplastic material, biofilm, joint replacement infection.

[Long-term results of the SVL total knee arthroplasty]. / Dlouhodobé výsledky náhrady kolenního kloubu SVL.

PURPOSE OF THE STUDY: The aim of the study was to evaluate the long-term results of the total knee replacement Beznoska SVL implanted at the 1st Department of Orthopaedic Surgery, 1st Faculty of Medicine, Charles University and Motol University Hospital Prague, in the 1997/2009 period. MATERIAL AND METHODS: The SVL implant is a non-constrained knee replacement, anatomically similar to the bone it replaces, which preserves the posterior cruciate ligament. A total of 1101 knee joint replacements were evaluated in 973 patients, of whom 128 underwent bilateral arthroplasty. Kaplan-Meier curves were used to estimate the cumulative survival of implants. Clinical outcomes were assessed using the Knee Society clinical rating system (KS score) and radiographic data evaluation was also included. RESULTS: Using KS scores, the results were excellent in 997, good in 75, satisfactory in 19 and poor in 10 knees. The average range of motion was 0.16 to 106.31 degrees. The complications included flexion contracture, as the most frequent problem (13 knees), 10 knees were infected, aseptic loosening due to polyethylene granuloma was found in eight knees and anterior knee pain was experienced in six cases. At follow-up of 12.5 years implant survivorship was 98 %, as evaluated by the Kaplan-Meier analysis. DISCUSSION: A comparison of SVL implant survivorship with other knee replacement designs is discussed. It should be emphasized that the clinical outcome depends not only on implant quality, but also on the operative technique used and the surgeon's experience and skills. It is the SVL system that allows for the balancing of knee joint stability and thus enables even less experienced surgeons to make use of a more sophisticated implantation technique. CONCLUSIONS: Total knee replacement using the SVL Beznoska implant is a safe, reliable and economic treatment with excellent clinical outcomes.

[Medin modular implant for total knee arthroplasty--mid-term results]. / Strednedobé výsledky u náhrad kolenního kloubu Medin Modular.

PURPOSE OF THE STUDY To evaluate the mid-term results of total knee arthroplasty (TKA) using a Medin Modular joint prosthesis in a standard design preserving the posterior cruciate ligament. MATERIAL The study comprised 206 consecutive total knee arthroplasties, 10 bilateral, 60 in men and 136 in women. Twelve patients died of causes unrelated to the surgery and 14 knee replacements were lost to follow-up. A total of 180 were evaluated at an average follow-up of 6.5 years (range, 5 to 8.7 years). The patients ranged in age from 43 to 84 years (average, 69.5 years). The basic indication for surgery was osteoarthritis in 179 and rheumatoid arthritis in 37 cases. METHODS Pain, range of motion, stability and function were scored on a 100-point scale of the Hospital for Special Surgery (HSS) Scoring System. Subjective satisfaction was essessed by the patient's willingness to undergo the surgery again. At yearly intervals, radiographs in two projections were examined for radiolucent lines around the implant. The Kaplan-Meier survival curve was evaluated for the whole group and compared with that for non-infected cases only. The mechanical properties of the implant were most reliably shown by the survival curve for the subgroup of knee replacements free of infection. RESULTS At the final follow-up out of 180 knees, 169 were fully functioning and 11 required revision arthroplasty for the following reasons: polyethylene wear, one knee; instability, two; infection, six; patellar fracture, one; and problems associated with the femoro-patellar joint, one knee. The Kaplan-Meier curve for the whole group showed survival of 92 % of the implants at the end of the 9-years follow-up time. In the infection-free subgroup, in which aseptic loosenings were only included, there was a 95 % survival. The average range of flexion was over 106 degrees, and only 11 knees had flexion below 90 degree lack of. Extension from 5 to 10 degrees was found in four knees. Thirteen knees showed instability that did not interfere with function. In 191 knees, after surgery alignment was optimal, between 0 and 5-degree valgus; in 11 knees varus up to 5 degrees and valgus up to 10 degrees were found. No pain was recorded in 123 knees, occasional pain with no effect on function in 36 cases, and moderate pain after weight-bearing in 10 knees. By the HSS score, 136 knees had excellent and very good (over 90 points) outcomes and 21 had unsatisfactory or poor outcomes (below 85 points); the remaining 23 had satisfactory outcomes (between 89 and 85 points). The subjective evaluation was positive for 156 knees. Of 169 TKA evaluated radiographs, 141 were without signs of radiolucency, 17 showed a slight marginal radiolucent line and 11 had a more pronounced radiolucent line up to 1 mm in width, but without progression. DISCUSSION A total of 93 % of total replacements were evaluated and 7 % were lost to follow-up. Therefore, the number of remaining patients is big enough to make the group valid for assessment. The rate of complications, including 2.9 % of infected knees, is in agreement with the reported values. The occurence of polyethylene wear was negligible. A comparison of the cumulative survival curve for the whole group with that for the infection-free subgroup showed that the effect of infection on the TKA outcome was statistically significant (p=0.0431), and that late infection remains the most serious complication. Aseptic loosening plays a less important role in implant survival evaluated at mid-term intervals. CONCLUSIONS The rate of complications for Medin Modular implants evaluated at an average follow-up of 6.5 years is not different from the values reported for similar prostheses. The most serious complication is late infection. Persistent pain is usually located to the femoro-patellar articulation, but it seldom markedly affects joint function. The cumulative survival curve for the whole group was 92 % at a 9 years. The HSS evaluation of the whole group showed that 75 % of the knees achieved mor than 90 points.

[Seven-year clinical experience with the SVL/Beznoska implant for total knee arthroplasty]. / Sedmileté klinické zkusenosti s náhradou kolenního kloubu SVL / Beznoska.

PURPOSE OF THE STUDY: The aim of the study was to evaluate our seven-year experience with the anatomic, non-constrained SVL/Beznoska implant for total knee replacement. MATERIAL: A total of 374 cemented total knee replacements, using the SVL/Beznoska implant, were evaluated in 333 patients treated at the First Orthopedic Clinic Charles University in Prague, during a seven-year period. In addition, a patellar replacement was used in five of these patients. Included in the evaluation were also eight non-cemented and hybrid SVL/Beznoska implants used 6 years ago. METHODS: The aim of the study was to evaluate the results in terms of implant function. Therefore, the longevity of implants was assessed by Kaplan-Meier's survival analysis. Another criterion was the flexion achieved. To be able to compare our clinical results involving the SVL/Beznoska implant with other, foreign types of implants, the patients were evaluated on the basis of the New Jersey Orthopaedics Hospital Knee Evaluation System. RESULTS: The Kaplan-Meier's survival score was evaluated. The mean maximum flexion achieved in the patients with SVL implants was 107 degrees . The evaluation by the New Jersey Orthopaedics Hospital Knee Evaluation System showed excellent outcomes in 269 (72 %) patients, good outcomes in 79 (21 %) patients, satisfactory in 19 (5 %) and poor in 7 (2 %) patients. There was no mechanical failure of the implant, such as break of an implant or dislocation of a PE component. Six infected implants and four aseptic loosenings were recorded. Three patients diagnosed with an infected total knee replacement had been treated for rheumatoid arthritis for a long time. One patient was on dialysis for renal insufficiency and one had erysipelas. DISCUSSION: The results of our group with the SVL/Beznoska implant were compared with those obtained from the group of 63 patients who underwent total knee arthroplasty with the LCS implant. In these patients, the mean maximum flexion achieved was 105 degrees , and the criteria of the Knee Evaluation System showed excellent outcomes in 81 %, good in 16 % and satisfactory in 3 % of the patients. No unsatisfactory outcome was recorded. Considering the fact that the LCS implant was used only in younger and active patients, the outcomes achieved with the SVL/Beznoska system can be regarded as very good. Of the six patients with infectious complications, three were treated with immunosuppressive therapy for rheumatoid arthritis, one was on dialysis for renal insufficiency and one experienced a flare-up of erysipelas. CONCLUSIONS: The most important outcome of the evaluation of 374 total knee replacements, using the SVL implant carried out at the First Orthopedic Department of the First Faculty of Medicine, Charles University, was the finding of a perfect function of all components in all patients treated. None of the complications occurring in our group was associated with the use of this implant.