Florian-D. Naal

Meniscal allograft processing procedures, in particular gamma irradiation, deteriorate the biomechanical and biological properties of the transplanted tissue. High hydrostatic pressure (HHP) treatment, widely used in food technology to inactivate microorganisms while preserving natural compounds, might serve as a gentle alternative to gamma irradiation in the processing of meniscal allografts. We therefore investigated the effects of HHP treatment on the biomechanical and immunohistochemical properties of meniscal cartilage. Specimens of bovine menisci were treated with HHP for 10 min (20°C) at 300 MPa and 600 MPa. Untreated control samples were left at room temperature and ambient pressure. We performed repetitive cycling indentation‐tests to assess the biomechanical properties—in particular the viscoelastic behavior—of HHP treated and untreated meniscal specimens. Immunohistochemical analysis for collagens type I, II, and III and for the proteoglycans versican, aggrecan and for link‐protein was performed by immunolabeling cross‐sections of untreated and at 600 MPa HHP treated specimens. Comparing untreated and HHP treated meniscal specimens there were no significant differences for all tested biomechanical parameters. All cross‐sections of untreated and HHP treated specimens stained positive for the collagens and proteoglycans. We demonstrated that meniscal cartilage can be treated by HHP at levels as high as 600 MPa without affection of the biomechanical and immunochistochemical properties. Therefore, HHP treatment might serve as a gentle alternative to gamma irradiation in the processing of meniscal allografts. Further research is necessary to verificate the present results in vivo. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008

Clindamycin is an antibiotic frequently used in different local application forms for the treatment of prosthetic joint infections, chronic osteomyelitis or as infection prophylaxis in bone cement. No information is available regarding its direct effects on bone cells, although very high local effective antibiotic concentrations can be achieved.

Background: There is a lack of detailed information concerning patients’ sports and recreational activities after unicompartmental knee arthroplasty. Hypothesis: Patients treated by unicompartmental knee arthroplasty will be able to return to sports and activity. Study Design: Case series; Level of evidence, 4. Methods: The authors surveyed 83 patients by postal questionnaires to determine their sporting and recreational activities at a mean follow-up of 18 ± 4.6 months (range, 12-28) after unicompartmental knee arthroplasty. For data analysis, patients were divided into groups of women and men, and older and younger patients (those above and below the median age of the group). The authors also assessed the state of general health (SF-36) of the patients at the time of the survey and compared the results with those of a matched (for age and side-diagnoses) reference population. Results: Before surgery, 77 of 83 patients were engaged in an average of 5.0 sports and recreational disciplines; postoperatively, 73 (88%) participated in an average of 3.1 different sports disciplines, resulting in a return to activity rate of 95%. The frequency of activities (sessions per week) was 2.9 preoperatively and remained constant at the time of survey (2.8). The group of older patients (mean age 73.0 y) revealed a significantly higher frequency than the group of younger patients (mean age 57.8 y). The minimum session length decreased from 66 minutes before surgery to 55 minutes after surgery. The most common activities after surgery were hiking, cycling, and swimming. Several high-impact activities, as well as the winter disciplines of downhill- and cross-country skiing had a significant decrease in participating patients. The majority of the patients (90.3%) stated that surgery had maintained or improved their ability to participate in sports or recreational activities. The patients generally scored very high on the SF-36 compared with the matched reference population. Higher SF-36 values in the physical-related domains correlated with an increased level of activity (r = 0.425). The preoperative body mass index showed a weak, negative correlation with the postoperative extent of activities (r = —0.282). Conclusion: The majority of patients returned to sports and recreational activity after unicompartmental knee arthroplasty. However, the numbers of different disciplines patients were engaged in decreased as well as the extent of activities. The activities in which most patients participated were primarily low- or midimpact. The patients scored higher on the SF-36 than age-related norms, which might be due to the patient-selection process for unicompartmental knee arthroplasty and geographical differences.

Background: No information is available concerning patients’ sports activity after hip resurfacing arthroplasty. Hypothesis: Patients treated by hip resurfacing arthroplasty will be able to achieve a high level of sports activity. Study Design: Case series; Level of evidence, 4. Methods: We surveyed 112 patients by postal questionnaire to determine their sporting activities at a mean of 23.5 (range, 9—40) months after hip resurfacing surgery. Data were also analyzed separately for older and younger patients and women and men, respectively. Results: Of 112 patients, 110 participated in an average of 4.6 sport disciplines after surgery, compared with 105 patients preoperatively engaged in an average of 4.8 disciplines. About 26% performed sports 4 times per week or more—almost 60% for longer than 60 min at each session. A high proportion of our patients were still engaged in downhill skiing (51%) and in high-impact disciplines such as tennis (12%) or contact sports (22%). More than 50% of the patients commenced sports within the first 3 months after surgery. During activities, 70% were completely pain-free. The group of older patients (mean age, 60.2 years) participated in more different disciplines with a higher weekly frequency and longer session length than younger patients (mean age, 46.4 years). Conclusion: The present study reports for the first time on the detailed sports activity and activity extent after hip resurfacing arthroplasty. Our patients could return to a high level of sports participation after surgery. Age-related differences were found that have not yet been published. Nevertheless, further follow-up is necessary to assess the influence of high-level activity on loosening and revision rates after hip resurfacing arthroplasty.

The local application of antibiotics in bone cement achieves high local effective antibiotic concentrations. Cefuroxime is widely used for antibiotic prophylaxis in orthopedic surgery, and several reports highlighted a beneficial outcome if cefuroxime‐impregnated bone cement was used, but there is a lack of information of direct cefuroxime effects on human bone cells. We, therefore, cultured osteoblasts, previously derived from human trabecular bone specimens and used as a cell‐pool further on, with different concentrations of cefuroxime (0–1000 μg/mL) for 24, 48, or 72 h. For reversibility testing, osteoblasts were cultivated for 24 h with cefuroxime followed by 48 h without antibiotics. Cell proliferation (MTT), cytotoxicity (lactate dehydrogenase (LDH)‐activity), cell metabolism (alkaline phosphatase (ALP)‐activity), and extracellular matrix calcification (Alizarin staining) were assessed after antibiotic treatment. Cefuroxime concentrations of 25–100 μg/mL had little or no effect on cellular proliferation. Proliferation was significantly stimulated at 250 and 1000 μg/mL at each time. LDH‐activity significantly increased at the highest concentration of 1000 μg/mL at 72 h. ALP‐activity first increased at lower concentrations and then significantly decreased at 1000 μg/mL at 48 and 72 h. Similar to ALP‐activity, calcification increased at lower concentrations and was not detectable at 1000 μg/mL. All revealed effects at 24 h were at least partially reversible. In the present study, we demonstrated that cefuroxime at lower concentrations had no inhibiting effects on human osteoblasts. In contrast, higher concentrations significantly altered osteoblastic function. When administered locally in total joint arthroplasty, for example, in antibiotic‐impregnated bone cement, cefuroxime might critically impair osteoblastic function and periprosthetic bone metabolism. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007