Biocompatibility and degradation comparisons of four biodegradable copolymeric osteosynthesis systems used in maxillofacial surgery: A goat model with four years follow-up.

Applying biodegradable osteosyntheses avoids the disadvantages of titanium osteosyntheses. However, foreign-body reactions remain a major concern and evidence of complete resorption is lacking. This study compared the physico-chemical properties, histological response and radiographs of four copolymeric biodegradable osteosynthesis systems in a goat model with 48-months follow-up. The systems were implanted subperiosteally in both tibia and radius of 12 Dutch White goats. The BioSorb FX [poly(70LLA-co-30DLLA)], Inion CPS [poly([70-78.5]LLA-co-[16-24]DLLA-co-4TMC)], SonicWeld Rx [poly(DLLA)], LactoSorb [poly(82LLA-co-18GA)] systems and a negative control were randomly implanted in each extremity. Samples were assessed at 6-, 12-, 18-, 24-, 36-, and 48-month follow-up. Surface topography was performed using scanning electron microscopy (SEM). Differential scanning calorimetry and gel permeation chromatography were performed on initial and explanted samples. Histological sections were systematically assessed by two blinded researchers using (polarized) light microscopy, SEM and energy-dispersive X-ray analysis. The SonicWeld Rx system was amorphous while the others were semi-crystalline. Foreign-body reactions were not observed during the complete follow-up. The SonicWeld Rx and LactoSorb systems reached bone percentages of negative controls after 18 months while the BioSorb Fx and Inion CPS systems reached these levels after 36 months. The SonicWeld Rx system showed the most predictable degradation profile. All the biodegradable systems were safe to use and well-tolerated (i.e., complete implant replacement by bone, no clinical or histological foreign body reactions, no [sterile] abscess formation, no re-interventions needed), but nanoscale residual polymeric fragments were observed at every system's assessment.

Meniscus surgery is still widely performed in the treatment of degenerative meniscus tears in The Netherlands.

PURPOSE: Studies have demonstrated rising incidences of meniscus procedures for degenerative meniscus tears in several countries, despite accumulating evidence that questions the efficacy of the treatment. It is not clear if this rise in incidences also applies to the practice of arthroscopic surgery in the Netherlands. The objective of this study was, therefore, to evaluate the number of meniscal surgeries performed in the Netherlands between 2005 and 2014. METHODS: We used registry-based data on meniscal surgeries that originated from Dutch national hospital basic care registrations from 2005 to 2014. Poisson regression models were used to test differences in incidences of meniscus surgeries performed in the Netherlands between 2005 and 2014, and to find out if changes in incidences over this period differed for younger and older patients. RESULTS: The number of meniscus surgeries was highest in patients aged 40-65 years, who accounted for half of the total number of meniscal surgeries. The incidences of meniscus surgeries decreased from 2005 to 2014 (p < 0.001); this decrease was observed in all age groups, although the decrease in incidences was more pronounced for younger patients (aged less than 40 years) compared to middle-aged and older patients (aged 40 years and older) (p < 0.001). CONCLUSIONS: The implementation of a nationwide guideline for arthroscopic procedures for meniscus tears may have contributed to a decrease in incidences of meniscus procedures. Despite accumulating evidence that questions the rationalisation and effectiveness of the treatment, meniscus surgery is still widely performed in the treatment of degenerative meniscus tears in the Netherlands, demonstrating a delay in the dissemination, acceptance, and implementation of clinical evidence in the practice of arthroscopic surgery in the Netherlands. LEVEL OF EVIDENCE: II.

Augmented cartilage regeneration by implantation of cellular versus acellular implants after bone marrow stimulation: a systematic review and meta-analysis of animal studies.

Bone marrow stimulation may be applied to regenerate focal cartilage defects, but generally results in transient clinical improvement and formation of fibrocartilage rather than hyaline cartilage. Tissue engineering and regenerative medicine strive to develop new solutions to regenerate hyaline cartilage tissue. This systematic review and meta-analysis provides a comprehensive overview of current literature and assesses the efficacy of articular cartilage regeneration by implantation of cell-laden versus cell-free biomaterials in the knee and ankle joint in animals after bone marrow stimulation. PubMed and EMBASE (via OvidSP) were systematically searched using tissue engineering, cartilage and animals search strategies. Included were primary studies in which cellular and acellular biomaterials were implanted after applying bone marrow stimulation in the knee or ankle joint in healthy animals. Study characteristics were tabulated and outcome data were collected for meta-analysis for studies applying semi-quantitative histology as outcome measure (117 studies). Cartilage regeneration was expressed on an absolute 0-100% scale and random effects meta-analyses were performed. Implantation of cellular biomaterials significantly improved cartilage regeneration by 18.6% compared to acellular biomaterials. No significant differences were found between biomaterials loaded with stem cells and those loaded with somatic cells. Culture conditions of cells did not affect cartilage regeneration. Cartilage formation was reduced with adipose-derived stem cells compared to other cell types, but still improved compared to acellular scaffolds. Assessment of the risk of bias was impaired due to incomplete reporting for most studies. Implantation of cellular biomaterials improves cartilage regeneration compared to acellular biomaterials.

In Vivo Performance of a Novel, Anatomically Shaped, Total Meniscal Prosthesis Made of Polycarbonate Urethane: A 12-Month Evaluation in Goats.

BACKGROUND: Injury or loss of the meniscus generally leads to degenerative osteoarthritic changes in the knee joint. However, the treatment options for symptomatic patients with total meniscectomy are limited. Therefore, we developed a novel, anatomically shaped, total meniscal implant made of polycarbonate urethane. PURPOSE: To evaluate the in vivo performance of this novel total meniscal implant. The assessment particularly focused on the implant's response to long-term physiological loading in a goat model and its chondroprotective capacity in comparison to clinically relevant controls. STUDY DESIGN: Controlled laboratory study. METHODS: Surgery was performed to the stifle joint of 26 female Saanen goats, subdivided into 4 groups: implant, allograft, total meniscectomy, and sham surgery. The sham group's contralateral joints served as nonoperated controls. After 12 months of follow-up, investigators evaluated implant wear, deformation, and the histopathological condition of the synovium and cartilage. RESULTS: Wear of the implant's articulating surfaces was minimal, which was confirmed by the absence of wear particles in the synovial fluid. Implant deformation was limited. However, one implant failed by complete tearing of the posterior horn extension. No differences in cartilage histopathological condition were observed for the implant, allograft, and meniscectomy groups. However, locally, the cartilage scores for these groups were significantly worse than those of the nonoperated controls. CONCLUSION: Whereas this study demonstrated that the novel implant is resistant to wear and that deformation after 12 months of physiological loading is acceptable, reinforcement of the implant horns is necessary to prevent horn failure. Although the implant could not protect the cartilage from developing degenerative changes, the progression of damage was similar in the allograft group. CLINICAL RELEVANCE: This novel polycarbonate urethane implant may have the potential to become an alternative treatment for symptomatic patients with total meniscectomy.

Improved cartilage regeneration by implantation of acellular biomaterials after bone marrow stimulation: a systematic review and meta-analysis of animal studies.

Microfracture surgery may be applied to treat cartilage defects. During the procedure the subchondral bone is penetrated, allowing bone marrow-derived mesenchymal stem cells to migrate towards the defect site and form new cartilage tissue. Microfracture surgery generally results in the formation of mechanically inferior fibrocartilage. As a result, this technique offers only temporary clinical improvement. Tissue engineering and regenerative medicine may improve the outcome of microfracture surgery. Filling the subchondral defect with a biomaterial may provide a template for the formation of new hyaline cartilage tissue. In this study, a systematic review and meta-analysis were performed to assess the current evidence for the efficacy of cartilage regeneration in preclinical models using acellular biomaterials implanted after marrow stimulating techniques (microfracturing and subchondral drilling) compared to the natural healing response of defects. The review aims to provide new insights into the most effective biomaterials, to provide an overview of currently existing knowledge, and to identify potential lacunae in current studies to direct future research. A comprehensive search was systematically performed in PubMed and EMBASE (via OvidSP) using search terms related to tissue engineering, cartilage and animals. Primary studies in which acellular biomaterials were implanted in osteochondral defects in the knee or ankle joint in healthy animals were included and study characteristics tabulated (283 studies out of 6,688 studies found). For studies comparing non-treated empty defects to defects containing implanted biomaterials and using semi-quantitative histology as outcome measure, the risk of bias (135 studies) was assessed and outcome data were collected for meta-analysis (151 studies). Random-effects meta-analyses were performed, using cartilage regeneration as outcome measure on an absolute 0-100% scale. Implantation of acellular biomaterials significantly improved cartilage regeneration by 15.6% compared to non-treated empty defect controls. The addition of biologics to biomaterials significantly improved cartilage regeneration by 7.6% compared to control biomaterials. No significant differences were found between biomaterials from natural or synthetic origin or between scaffolds, hydrogels and blends. No noticeable differences were found in outcome between animal models. The risk of bias assessment indicated poor reporting for the majority of studies, impeding an assessment of the actual risk of bias. In conclusion, implantation of biomaterials in osteochondral defects improves cartilage regeneration compared to natural healing, which is further improved by the incorporation of biologics.

The Effect of Door Openings on Numbers of Colony Forming Units in the Operating Room during Hip Revision Surgery.

BACKGROUND: The aim of this study was to investigate the effect of door opening rates on air quality in the operation room during hip revision surgery by measuring the number of colony forming units per cubic meter (CFU/m(3)). METHODS: During 70 hip revision operations the number of CFU/m(3) was measured at four time points. Factors that may influence air quality were recorded, including the number of persons present, duration of surgery, and door opening rates. The measured CFU/m(3) was dichotomized as either acceptable (≤20 CFU/m(3)) or not acceptable (>20 CFU/m(3)). To determine whether door openings were associated with CFU/m(3) values, we used generalized linear mixed models to model the dichotomized repeatedly measured CFU/m(3) values. RESULTS: The median number of door openings per operation was eight (range, 0-72), the median duration of surgery was 145 min (range, 60-285), and the median number of persons present during surgery was eight (range, 5-10). Adjusted for number of persons in the operation room and duration of surgery, the number of door openings per operation was associated (odds ratio [OR] 1.05 [95% confidence interval {CI} 1.02-1.09]; p = 0.003) with an unacceptable number of CFU/m(3). CONCLUSIONS: In conclusion, a substantial association between number of door openings and an unacceptable number (>20) of CFU/m(3) was found. Adjusted for number of persons in the operation room and duration of surgery, every door opening increased the odds of unacceptable CFU/m(3) values by 5%. Number of persons present during surgery and duration of surgery were not related to CFU/m(3).

Societal and Economic Effect of Meniscus Scaffold Procedures for Irreparable Meniscus Injuries.

BACKGROUND: Meniscus scaffolds are currently evaluated clinically for their efficacy in preventing the development of osteoarthritis as well as for their efficacy in treating patients with chronic symptoms. Procedural costs, therapeutic consequences, clinical efficacy, and future events should all be considered to maximize the monetary value of this intervention. PURPOSE: To examine the socioeconomic effect of treating patients with irreparable medial meniscus injuries with a meniscus scaffold. STUDY DESIGN: Economic and decision analysis; Level of evidence, 2. METHODS: Two Markov simulation models for patients with an irreparable medial meniscus injury were developed. Model 1 was used to investigate the lifetime cost-effectiveness of a meniscus scaffold compared with standard partial meniscectomy by the possibility of preventing the development of osteoarthritis. Model 2 was used to investigate the short-term (5-year) cost-effectiveness of a meniscus scaffold compared with standard partial meniscectomy by alleviating clinical symptoms, specifically in chronic patients with previous meniscus surgery. For both models, probabilistic Monte Carlo simulations were applied. Treatment effectiveness was expressed as quality-adjusted life-years (QALYs), while costs (estimated in euros) were assessed from a societal perspective. We assumed €20,000 as a reference value for the willingness to pay per QALY. Next, comprehensive sensitivity analyses were performed to identify the most influential variables on the cost-effectiveness of meniscus scaffolds. RESULTS: Model 1 demonstrated an incremental cost-effectiveness ratio of a meniscus scaffold treatment of €54,463 per QALY (€5991/0.112). A threshold analysis demonstrated that a meniscus scaffold should offer a relative risk reduction of at least 0.34 to become cost-effective, assuming a willingness to pay of €20,000. Decreasing the costs of the meniscus scaffold procedure by 33% (€10,160 instead of €15,233; an absolute change of €5073) resulted in an incremental cost-effectiveness ratio of €7876 per QALY. Model 2 demonstrated an incremental cost-effectiveness ratio of a meniscus scaffold treatment of €297,727 per QALY (€9825/0.033). On the basis of the current efficacy data, a meniscus scaffold provides a relative risk reduction of "limited benefit" postoperatively of 0.37 compared with standard treatment. A threshold analysis revealed that assuming a willingness to pay of €20,000, a meniscus scaffold would not be cost-effective within a period of 5 years. Most influential variables on the cost-effectiveness of meniscus scaffolds were the cost of the scaffold procedure, cost associated with osteoarthritis, and quality of life before and after the scaffold procedure. CONCLUSION: Results of the current health technology assessment emphasize that the monetary value of meniscus scaffold procedures is very much dependent on a number of influential variables. Therefore, before implementing the technology in the health care system, it is important to critically assess these variables in a relevant context. The models can be improved as additional clinical data regarding the efficacy of the meniscus scaffold become available.

Porous titanium particles for acetabular reconstruction in total hip replacement show extensive bony armoring after 15 weeks. A loaded in vivo study in 10 goats.

BACKGROUND AND PURPOSE: The bone impaction grafting technique restores bone defects in total hip replacement. Porous titanium particles (TiPs) are deformable, like bone particles, and offer better primary stability. We addressed the following questions in this animal study: are impacted TiPs osteoconductive under loaded conditions; do released micro-particles accelerate wear; and are systemic titanium blood levels elevated after implantation of TiPs? ANIMALS AND METHODS: An AAOS type-III defect was created in the right acetabulum of 10 goats weighing 63 (SD 6) kg, and reconstructed with calcium phosphate-coated TiPs and a cemented polyethylene cup. A stem with a cobalt chrome head was cemented in the femur. The goats were killed after 15 weeks. Blood samples were taken pre- and postoperatively. RESULTS: The TiP-graft layer measured 5.6 (SD 0.8) mm with a mean bone ingrowth distance of 2.8 (SD 0.8) mm. Cement penetrated 0.9 (0.3-1.9) mm into the TiPs. 1 reconstruction showed minimal cement penetration (0.3 mm) and failed at the cement-TiP interface. There were no signs of accelerated wear, metallic particle debris, or osteolysis. Median systemic titanium concentrations increased on a log-linear scale from 0.5 (0.3-1.1) parts per billion (ppb) to 0.9 (0.5-2.8) ppb (p=0.01). INTERPRETATION: Adequate cement pressurization is advocated for impaction grafting with TiPs. After implantation, calcium phosphate-coated TiPs were osteoconductive under loaded conditions and caused an increase in systemic titanium concentrations. However, absolute levels remained low. There were no signs of accelerated wear. A clinical pilot study should be performed to prove that application in humans is safe in the long term.

[Treatment of cartilaginous defects in the knee: recommendations from the Dutch Orthopaedic Association]. / Behandeling van kraakbeendefecten in de knie: advies van de Nederlandse Orthopaedische Vereniging.

Cartilaginous defects in the knee occur frequently and can cause the patient considerable limitations. They are diagnosed and classified by means of MRI and arthroscopy. The surgical options available to treat deep chondral lesions include bone marrow stimulation techniques (microfracture treatment), chondrocyte therapies (autologous chondrocyte implantation) and tissue replacement therapies (osteochondral autologous transplantation). Microfracture treatment and osteochondral autologous transplantation are suitable for treating chondral lesions that extend to the subchondral bone and are smaller than 2 and 4 cm2, respectively. Autologous chondrocyte implantation is a suitable method for treating single symptomatic chondral lesions larger than 2 cm2 in adults up to 50 years of age. There are no significant differences regarding the effectiveness of microfracture treatment, autologous chondrocyte implantation and osteochondral autologous transplantation for small defects: all show good clinical and functional short- and medium-term results. New second- and third-generation autologous chondrocyte implantation techniques seem to yield more sustainable tissue repair and better clinical long-term results for lesions larger than 4 cm2 in comparison to microfracture treatment.

Synthetic meniscus replacement: a review.

The number of meniscus-related operations continues to rise due to the ageing and more active population. Irreparable meniscal lesions generally require (partial) meniscectomy. Although a majority of the patients benefit from pain relief and functional improvement post-meniscectomy, some remain symptomatic. As an alternative to a meniscal allograft, which is only indicated for the severely damaged meniscus, most patients can nowadays be treated by implantation of a synthetic meniscal substitute. Currently three of these implants, two partial and one total replacement, are clinically available and several others are in the stage of preclinical testing. Grossly, two types of meniscal substitutes can be distinguished: porous, resorbable implants that stimulate tissue regeneration and solid, non-resorbable implants that permanently replace the whole meniscus. Although the implantation of a porous meniscus replacement generally seems promising and improves clinical outcome measures to some degree, their superiority to partial meniscectomy still needs to be proven. The evaluation of new prostheses being developed requires a wider focus than has been adopted so far. Upon selection of the appropriate materials, preclinical evaluation of such implants should comprise a combination of (in vitro) biomechanical and (in vivo) biological tests, while up to now the focus has mainly been on biological aspects. Obviously, well-defined randomised controlled trials are necessary to support clinical performance of new implants. Since the use of a meniscus replacement requires an additional costly implant and surgery compared to meniscectomy only, the clinical outcome of new products should be proven to surpass the results of the conventional therapies available.

Septic failure is not a septic loosening: A case report of a failed shoulder prosthesis.

Septic failure of a shoulder arthroplasty due to a low-grade infection is generally called septic loosening. However, it is often not investigated if a prosthesis is genuinely loose. We present a case of a failed resurfacing prosthesis in a 70-year-old woman. This prosthesis failed due to a low-grade infection and a revision procedure was mandatory. All intraoperative cultures were positive and revealed a combination of bacteria. Nevertheless, histology revealed a macroscopic and a microscopic stable prosthesis with full osseointegration beneath the prosthesis. The general conception is that an infection leads to interface formation (with neutrophils) and loosening of the prosthesis. We debate this with the presentation of this case of a failed shoulder prosthesis and we think that periprosthetic infection and septic prosthetic loosening are two different entities.

Evaluation of subsidence, chondrocyte survival and graft incorporation following autologous osteochondral transplantation.

PURPOSE: The aim of this study was to evaluate subsidence tendency, surface congruency, chondrocyte survival and plug incorporation after osteochondral transplantation in an animal model. The potential benefit of precise seating of the transplanted osteochondral plug on the recipient subchondral host bone ('bottoming') on these parameters was assessed in particular. METHODS: In 18 goats, two osteochondral autografts were harvested from the trochlea of the ipsilateral knee joint and inserted press-fit in a standardized articular cartilage defect in the medial femoral condyle. In half of the goats, the transplanted plugs were matched exactly to the depth of the recipient hole (bottomed plugs; n = 9), whereas in the other half of the goats, a gap of 2 mm was left between the plugs and the recipient bottom (unbottomed plugs; n = 9). After 6 weeks, all transplants were evaluated on gross morphology, subsidence, histology, and chondrocyte vitality. RESULTS: The macroscopic morphology scored significantly higher for surface congruency in bottomed plugs as compared to unbottomed reconstructions (P = 0.04). However, no differences in histological subsidence scoring between bottomed and unbottomed plugs were found. The transplanted articular cartilage of both bottomed and unbottomed plugs was vital. Only at the edges some matrix destaining, chondrocyte death and cluster formation was observed. At the subchondral bone level, active remodeling occurred, whereas integration at the cartilaginous surface of the osteochondral plugs failed to occur. Subchondral cysts were found in both groups. CONCLUSIONS: In this animal model, subsidence tendency was significantly lower after 'bottomed' versus 'unbottomed' osteochondral transplants on gross appearance, whereas for histological scoring no significant differences were encountered. Since the clinical outcome may be negatively influenced by subsidence, the use of 'bottomed' grafts is recommended for osteochondral transplantation in patients.

Changes in articular cartilage after meniscectomy and meniscus replacement using a biodegradable porous polymer implant.

PURPOSE: To evaluate the long-term effects of implantation of a biodegradable polymer meniscus implant on articular cartilage degeneration and compare this to articular cartilage degeneration after meniscectomy. METHODS: Porous polymer polycaprolacton-based polyurethane meniscus implants were implanted for 6 or 24 months in the lateral compartment of Beagle dog knees. Contralateral knees were meniscectomized, or left intact and served as controls. Articular cartilage degeneration was evaluated in detail using India ink staining, routine histology, immunochemistry for denatured (Col2-¾M) and cleaved (Col2-¾C(short)) type II collagen, Mankin's grading system, and cartilage thickness measurements. RESULTS: Histologically, fibrillation and substantial immunohistochemical staining for both denatured and cleaved type II collagen were found in all three treatment groups. The cartilage of the three groups showed identical degradation patterns. In the 24 months implant group, degradation appeared to be more severe when compared to the 6 months implant group and meniscectomy group. Significantly more cartilage damage (India ink staining, Mankin's grading system, and cartilage thickness measurements) was found in the 24 months implant group compared to the 6 months implant group and meniscectomy group. CONCLUSION: Degradation of the cartilage matrix was the result of both mechanical overloading as well as localized cell-mediated degradation. The degeneration patterns were highly variable between animals. Clinical application of a porous polymer implant for total meniscus replacement is not supported by this study.

Long-term survivorship analysis of the cementless Spotorno femoral component in patients less than 50 years of age.

The long-term survival of the cementless Spotorno (CLS) femoral component (Zimmer Inc, Warsaw, USA) was evaluated in a consecutive series of 85 patients (100 hips) less than 50 years of age. The mean follow-up was 12.3 years. Two patients (3 hips) were lost to follow-up, and 3 (4 hips) died. The survival rate of the CLS stem was 96.9% (confidence interval [CI], 93.6%-100%) after 13 years based on revision of the stem for any reason. The survival of the stem with revision for aseptic loosening as the end point was 97.9% (CI, 95.1%-100%) at 13 years. The mean Harris hip score at time of follow-up was 94. The long-term survival of the CLS stem is excellent in patients less than 50 years of age.

Frictional and bone ingrowth properties of engineered surface topographies produced by electron beam technology.

BACKGROUND: Electron beam melting (E-beam) is a new technology to produce 3-dimensional surface topographies for cementless orthopedic implants. METHODS: The friction coefficients of two newly developed E-beam produced surface topographies were in vitro compared with sandblasted E-beam and titanium plasma sprayed controls. Bone ingrowth (direct bone-implant contact) was determined by implanting the samples in the femoral condyles of 6 goats for a period of 6 weeks. RESULTS: Friction coefficients of the new structures were comparable to the titanium plasma sprayed control. The direct bone-implant contact was 23.9 and 24.5% for the new surface structures. Bone-implant contact of the sandblasted and titanium plasma sprayed control was 18.2 and 25.5%, respectively. CONCLUSIONS: The frictional and bone ingrowth properties of the E-beam produced surface structures are similar to the plasma-sprayed control. However, since the maximal bone ingrowth had not been reached for the E-beam structures during the relatively short-term period, longer-term follow-up studies are needed to assess whether the E-beam structures lead to a better long-term performance than surfaces currently in use, such as titanium plasma spray coating.

Impregnation of bone chips with antibiotics and storage of antibiotics at different temperatures: an in vitro study.

BACKGROUND: Allograft bone used in joint replacement surgery can additionally serve as a carrier for antibiotics and serve as a prophylaxis against infections. However, in vitro dose-response curves for bone chips impregnated with different kinds of antibiotics are not available. In addition, while it would be desirable to add the antibiotics to allograft bone chips before these are stored in a bone bank, the effects of different storage temperatures on antibiotics are unknown. METHODS: Five different antibiotics (cefazolin, clindamycin, linezolid, oxacillin, vancomycin) were stored, both as pills and as solutions, at -80 degrees C, -20 degrees C, 4 degrees C, 20 degrees C and 37 degrees C; in addition, bone chips impregnated with cefazolin and vancomycin were stored at -80 degrees C and -20 degrees C. After 1 month, 6 months and 1 year, the activity of the antibiotics against Staphylococcus epidermidis was measured using an inoculated agar. The diameter of the S. epidermidis-free zone was taken as a measure of antibiotic activity. In a separate experiment, in vitro dose-response curves were established for bone chips impregnated with cefazolin and vancomycin solutions at five different concentrations. Finally, the maximum absorbed amounts of cefazolin and vancomycin were established by impregnating 1 g of bone chips with 5 ml of antibiotic solution. RESULTS: A decrease of the S. epidermidis-free zone was seen with oxacillin and cefazolin solutions stored at 37 degrees C for 1 month, with vancomycin stored at 37 degrees C for 6 months and with cefazolin and oxacillin solutions stored at 20 degrees C for 6 months. The activity of the other antibiotic solutions, pills and impregnated bone chips was not affected by storage. The in vitro dose-response curves show that the free-zone diameter increases logarithmically with antibiotic concentration. The absorbed antibiotic amount of one gram bone chips was determined. CONCLUSIONS: Storage of antibiotics in frozen form or storage of antibiotic pills at temperatures up to 37 degrees C for 12 months does not affect their activity. However, storage of antibiotic solutions at temperatures above 20 degrees C does affect the activity of some of the antibiotics investigated. The in vitro dose-response curve can be used to determine the optimal concentration(s) for local application. It provides the opportunity to determine the antibiotic content of bone chips, and thus the amount of antibiotics available locally after application.

Acetabular revision with impacted morselized cancellous bone graft and a cemented cup in patients with rheumatoid arthritis. A concise follow-up, at eight to nineteen years, of a previous report.

We previously reported our results at a minimum of three years after thirty-five revisions of total hip arthroplasty acetabular components in twenty-eight patients with rheumatoid arthritis. The revisions were performed with use of impacted morselized bone graft and a cemented cup. This update report presents the results at eight to nineteen years after the surgery, which, to our knowledge, is the longest follow-up available in the literature. No patient was lost to follow-up. Since our previous report, there were two additional cup failures due to aseptic loosening, at ten and sixteen years postoperatively. Kaplan-Meier analysis showed the probability of survival of the acetabular component at twelve years to be 80% (95% confidence interval, 65% to 95%) with removal of the cup for any reason as the end point and 85% (95% confidence interval, 71% to 99%) with aseptic loosening as the end point. Cup revisions performed with cement and use of impaction bone-grafting in patients with rheumatoid arthritis led to acceptable long-term prosthetic survival rates. This technique is attractive from a biological standpoint because of the possibility of maintaining acetabular bone stock.

The stability of impacted morsellized bone grafts in a metal cage under dynamic loaded conditions: an in vitro reconstruction of a segmental diaphyseal bone defect.

INTRODUCTION: Reconstructions of segmental diaphyseal bone defects with massive allografts are related to complications like nonunion and fractures. A reconstruction of these defects with a cage filled with an impacted morsellized bone graft could be an alternative. The bone graft in these cages should ideally be loaded to prevent resorption. Loading of morsellized bone grafts however can cause instability. The goal of this study was to assess the stability of an impacted morsellized bone graft in a cage under dynamic loaded conditions in an in vitro reconstruction of a segmental diaphyseal bone defect. The second goal was to assess the influence of cage type, washing of the graft and bone-cage fit. MATERIALS AND METHODS: Two different cage types were filled with impacted morsellized bone graft. The grafts were used washed and unwashed and in variable bone-cage fit conditions. We recorded the bone graft deformation in the cage under dynamic loaded conditions. RESULTS: Stability appeared to be not very sensitive to the cage type and whether the bone chips were washed or not. However, quality of the fit of the cage with the bone segment was an important parameter and should be optimized during surgery. CONCLUSIONS: Morsellized impacted bone graft in a cage is stable in dynamic loaded conditions in an in vitro reconstruction of a segmental diaphyseal bone defect. We believe that this method of reconstruction is a promising alternative for the reconstruction of large diaphyseal bone defects and should be tested relative to its biological merits in animal experiments.

In vitro testing of femoral impaction grafting with porous titanium particles: a pilot study.

The disadvantages of allografts to restore femoral bone defects during revision hip surgery have led to the search for alternative materials. We investigated the feasibility of using porous titanium particles and posed the following questions: (1) Is it possible to create a high-quality femoral graft of porous titanium particles in terms of graft thickness, cement thickness, and cement penetration? (2) Does this titanium particle graft layer provide initial stability when a femoral cemented stem is implanted in it? (3) What sizes of particles are released from the porous titanium particles during impaction and subsequent cyclic loading of the reconstruction? We simulated cemented revision reconstructions with titanium particles in seven composite femurs loaded for 300,000 cycles and measured stem subsidence. Particle release from the titanium particle grafts was analyzed during impaction and loading. Impacted titanium particles formed a highly interlocked graft layer. We observed limited cement penetration into the titanium particle graft. A total mean subsidence of 1.04 mm was observed after 300,000 cycles. Most particles released during impaction were in the phagocytable range (< 10 microm). There was no detectable particle release during loading. Based on the data, we believe titanium particles are a promising alternative for allografts. However, animal testing is warranted to investigate the biologic effect of small-particle release.

Biological effects of rinsing morsellised bone grafts before and after impaction.

Rinsing bone grafts before or both before and after impaction might have different effects on the incorporation of the graft. Rinsing again after impaction might negatively influence bone induction if growth factors released by impaction are washed away. We studied if transforming growth factor-betas (TGF-betas) and bone morphogenetic proteins (BMPs) are released from the mineralised matrix by impaction and if these released growth factors induce osteogenic differentiation in human mesenchymal stem cells (hMSCs). Rinsed morsellised bone allografts were impacted in a cylinder and the escaping fluid was collected. The fluid was analysed for the presence of TGF-betas and BMPs, and the osteoinductive capacity was tested on hMSCs. Abundant TGF-beta was present in the fluid. No BMPs could be detected. Osteogenic differentiation of hMSCs was inhibited by the fluid. Results from our study leave us only able to speculate whether rinsing grafts again after impaction has a beneficial effect on the incorporation process or not.