Release behavior of VAN from four types of CaP-ceramic granules using various loading methods at two different degrees of acidity.

The release behavior of vancomycin (VAN) from beta-tricalciumphosphate (ßTCP), hydroxyapatite (HA), glass ceramic (GC) and sponge-like collagen ßTCP granule composite (sponge) was studied. Vacuum and drip loading methods were compared. The influence of VAN concentration and pH on release behavior was analyzed with respect to a stable release level of VAN above the minimum inhibitory concentration over 14 days. Initially the morphology of the granule carrier systems was examined with ESEM, stereomicroscopy, µCT-imaging and Camsizer® regarding porosity, interconnecting pores and granule size. Drug release patterns following a vacuum and a drip loading method with VAN at concentrations of 5 and 50 mg/ml were compared. The influence of pH 7.4 compared to pH 5.0 on release behavior was studied. The drug was released in bidistilled water at 37 °C, the concentration determined by photometry at 220 nm. For statistical purposes, the mean and standard deviation were calculated and analyzed by Origin 9.1 Professional SR1 (OriginLab). Due to low interconnectivity and low porosity, the vacuum loading method was unable to attain complete drug loading of the ceramic granules. The sponge showed an inhomogeneous distribution of ßTCP granules. Drug release was high at pH 7.4, at pH 5.0 it practically did not occur. All samples except for the collagen-complex show an initial VAN burst release with a following steady release. Loading with 5 mg/ml concentrated VAN resulted in a higher percentage of available drug being released. However, when loaded with 50 mg/ml, the absolute amount of drug released was higher.

Distal tibial fractures and pilon fractures.

Fractures of the distal tibia are often very severe injuries that generally occur in the context of high-energy trauma and present with significant concomitant soft tissue involvement. Open fractures and extensive destruction of the articular surfaces are important challenges to the treating surgeon. In consequence the outcome for distal meta- and epiphyseal tibial fractures depends largely on the severity of the soft tissue injury and its management. Conventionally, tibial pilon fractures require surgical intervention. Conservative treatment would only be considered in some exceptional cases, for example, inoperability of the patient. Controversial discussion of optimal surgical technique and optimal timing of surgery is ongoing. There is broad consensus that soft tissue consolidation must have first priority as this is the basis for both fracture healing and good long-term outcomes. Surgical intervention can be managed as a one-stage or multi-stage procedure to achieve internal or external fracture fixation.

Reliability of leg alignment using the OrthoPilot system depends on knee position: a cadaveric study.

Despite the increase in clinical use of navigation systems in total knee arthroplasty, few studies have focused on the reproducibility of these systems. The aim of the present study was to assess the influence of knee position and observer experience on intra- and inter-observer agreement in limb alignment assessment with the OrthoPilot system. Limb alignment in the coronal plane and extension range of the knee were assessed in four embalmed cadaveric specimens by five independent observers and measurements were repeated four times to determine intra- and inter-observer agreement, expressed as intraclass correlation coefficients (ICCs). Additionally, navigation results were compared against figures from conventional measurement of leg alignment (ground truth). Intra- and inter-observer agreements were excellent for assessing the extension range (ICC, 0.97 and 0.95) and the coronal femuro-tibial axis in knee extension (ICC, 0.92 and 0.88) but were generally worse in knee flexion (ICC, 0.62 and 0.55). There was an increased tendency of intraobserver errors in observers with less clinical experience. Mean correlation with conventional measurements was fair (Spearman's rho 0.61). The OrthoPilot system showed excellent reproducibility for assessment of extension range and coronal limb alignment. However, assessments of coronal limb alignment in flexion were prone to error and caution should be taken when relying on these measurements.

Survival of human mesenchymal stromal cells from bone marrow and adipose tissue after xenogenic transplantation in immunocompetent mice.

INTRODUCTION: Mesenchymal stromal cells (MSC) represent an attractive cell population for tissue engineering purposes. As MSC are described as immunoprivileged, non-autologous applications seem possible. A basic requirement is the survival of MSC after transplantation in the host. The purpose of the current paper was to evaluate the survival of undifferentiated and osteogenically induced human MSC from different origins after transplantation in immunocompetent mice. METHODS: Human MSC were isolated from bone marrow (BMSC) and adipose tissue (ASC). After cultivation on mineralized collagen, MSC were transplanted subcutaneously into immunocompetent mice (n=12). Undifferentiated MSC (group A) were compared with osteogenic-induced MSC (group B). Human-specific in situ hybridization and anti-vimentin staining was used to follow MSC after transplantation. Quantitative evaluation of lymphocytes and macrophages was performed as a measure of immunologic rejection. Unloaded scaffolds served as controls (group C). Specimens were harvested at 4 and 8 weeks. RESULTS: Undifferentiated BMSC and ASC were detected in the majority of cases after xenogenic transplantation (group A, a total of 22 out of 24 cases), while osteogenic-induced MSC (group B) could be detected in only three of 24 cases. Quantification of lymphocytes and macrophages revealed significantly higher cell numbers in group B compared with group A (P<0.05). DISCUSSION: Our results suggest that undifferentiated MSC are candidates for non-autologous cell transplantation, while osteogenic-induced MSC seem to be eliminated by the host's immune system. This observation seems independent of the origin of MSC and applies to BMSC and ASC.

Primary stability of various forms of osteosynthesis in the treatment of fractures of the proximal tibia.

The treatment of fractures of the proximal tibia is complex and makes great demands on the implants used. Our study aimed to identify what levels of primary stability could be achieved with various forms of osteosynthesis in the treatment of diaphyseal fractures of the proximal tibia. Pairs of human tibiae were investigated. An unstable fracture was simulated by creating a defect at the metaphyseal-diaphyseal junction. Six implants were tested in a uniaxial testing device (Instron) using the quasi-static and displacement-controlled modes and the force-displacement curve was recorded. The movements of each fragment and of the implant were recorded video-optically (MacReflex, Qualysis). Axial deviations were evaluated at 300 N. The results show that the nailing systems tolerated the highest forces. The lowest axial deviations in varus and valgus were also found for the nailing systems; the highest axial deviations were recorded for the buttress plate and the less invasive stabilising system (LISS). In terms of rotational displacement the LISS was better than the buttress plate. In summary, it was found that higher loads were better tolerated by centrally placed load carriers than by eccentrically placed ones. In the case of the latter, it appears advantageous to use additive procedures for medial buttressing in the early phase.

Biomechanical evaluation of two innovative locking implants for comminuted olecranon fractures under high-cycle loading conditions.

INTRODUCTION: The relatively high complication rate after fixation of olecranon fractures has led to an increasing application of anatomically pre-contoured locking plate systems. The purpose of the present study was to conduct a biomechanical comparison of olecranon osteosyntheses by applying the Olecranon VA-LCP and the 3.5mm LCP Hook Plate (LCP, locking compression plate) to an unstable fracture model under high-cycle loading conditions. METHODS: After creating an unstable fracture (Schatzker type B), osteosynthesis was performed on eight pairs of fresh-frozen cadaveric ulnae by application of either the Olecranon VA-LCP (Synthes, Solothurn, Switzerland) or the 3.5mm LCP Hook Plate (Synthes, Solothurn, Switzerland). Loading (50,000 alternating loads, cyclic and sinusoidal 10-300 N) was conducted by application of tensile load with the elbow in 90° flexion to simulate the tensile strength of the triceps brachii. For statistical analysis, angular displacement in the region of the humeral trochlea was taken as a measure of olecranon dislocation. RESULTS: In Group 1 (Olecranon VA-LCP), a median angular displacement of 0.36° (minimum 0.10°; maximum 0.80°) was observed after 500 alternating loads. In Group 2 (3.5-mm LCP Hook Plate), the medial displacement was 0.80° (minimum 0.13°; maximum 2.72°). The difference was nonsignificant (p = 0.128). The mean value for angular displacement in Group 1 after 50,000 cycles was 0.80° (minimum 0.31°; maximum 1.99°), whereas in Group 2 a mean angular displacement of 2.02° (minimum 0.71°; maximum 6.40°) was recorded. The difference was statistically significant (p = 0.017). In Group 2, implant failure in the form of proximal plate pullout occurred in one construct after 756 cycles. CONCLUSION: A significantly higher biomechanical stability can be achieved in the fixation of unstable olecranon fractures by application of the Olecranon VA-LCP rather than the 3.5mm LCP Hook Plate.

The incidence of osteitis in open fractures: an analysis of 948 open fractures (a review of the Hannover experience).

Even though treatment protocols of open fractures have been improved in the past two decades, osteitis is still a major complication in these injuries. To investigate the primary factors responsible for posttraumatic osteitis, 19 cases of osteitis out of 297 open fractures (retrospective series from 1981 to 1983) and nine cases of osteitis out of 651 open fractures (prospective series from 1984 to 1989) were analyzed. The Hannover fracture scale was used for quantitative evaluation of the injury. A high prognostic index for bone infections was found for the amount of bone loss, the fracture type, the type of bacteriologic contamination, deep soft-tissue defects, compartment syndromes, vascular injuries, and soft-tissue infections.

Stabilisation of articular fractures of the distal humerus: early experience with a novel perpendicular plate system.

INTRODUCTION: The treatment of fractures of the distal humerus is difficult and involves the risk of bad functional results, particularly with articular fractures or impaired bone quality. Anatomical reconstruction and stable fixation allowing early mobilisation of the elbow are the basic prerequisites for good clinical outcomes. The aim of our study was to evaluate whether the Distal Humerus Plate (DHP, Synthes), a novel, perpendicular, fixed-angle plate system, fulfils the requirements for this treatment goal. METHODS: From 2004 to 2007, 46 consecutive patients (19 men and 21 women; mean age of 60.5 years) underwent open reduction and internal fixation with the new DHP system. Six patients were lost to follow up. The remaining 40 patients were followed up for 11 months (range 4-24 months). Follow up involved assessment of functional outcome using the Mayo Elbow Performance Score (MEPS) and Liverpool Elbow Score (LES), reduction results and complication rates. Subgroup analyses involved comparisons of younger (<60 years) to elderly (> or =60 years) patients and type C3 injuries versus other fracture patterns. RESULTS: Only six cases received primary internal fixation, whilst 31 patients were temporarily stabilised by either external fixation or cast before ORIF could be performed. Three patients were treated for implant failure (systems other than DHP) after surgery in other hospitals. The mean time from injury to internal fixation was 7 days. Open fractures were present in 10 cases. Olecranon osteotomy was required for reduction in 35 cases. Mean operation time was 215 min. 'Good' or 'excellent' results were observed in 29/40 patients. Median MEPS and LES were 84 and 8.1 points, respectively. Mean ROM was 100 degrees. We found no significant differences in the subgroup analyses; however, there was a tendency towards better functional results in younger patients and injuries without comminution of the articular surface. Complications comprised two superficial wound infections, two cases of heterotopic ossification, one case of delayed union and five cases of transient ulnar neuropathy. Implant failure was observed twice in one patient. CONCLUSION: Open reduction and internal fixation with the DHP system provides reliable, stable fixation allowing early functional mobilisation of the elbow joint, even in complex fractures and impaired bone quality, resulting in good outcomes for the majority of patients. The complication rate reported here is comparable to that of other implants, but the low number of implant failures is promising and warrants further investigation.

Evaluation of Singh index for assessment of osteoporosis using digital radiography.

Evaluation of Singh index (SI) as a simple means for estimating bone mass on radiographs has been subject of numerous studies. All of these studies used plain film radiographs for assessment of SI. Digital radiography may improve validity and reliability of SI assessment. Aim of this study was to evaluate SI gradings assessed on digital radiographs. Digital pelvic radiographs of 100 patients were graded using SI by five independent observers (two radiologists, three traumatologists) blinded to dual energy X-ray absorptiometry (DXA) results and re-graded by all observers for assessment of intraobserver agreement. SI was correlated with DXA measurements and after grouping the patients according to World Health Organisation (WHO) criteria (osteoporosis, osteopenia, normal). Logistic regression analysis was performed in order to identify influential parameters on the SI grading process. Mean intraobserver agreement was 0.648+/-0.18 (Kendall's Tau) and 0.43+/-0.28 (kappa). Mean interobserver agreement was 0.488+/-0.193 (Kendall's Tau) and 0.199+/-0.248 (kappa). Mean correlation between SI and trochanteric BMD and T scores was 0.219+/-0.04 and 0.210+/-0.05 (Spearman's coefficient). Only one observer (senior radiologist) reached the significance level after grouping the patients' DXA results according to WHO criteria and correlating the results with SI gradings. Logistic regression analysis revealed a significant influence of trochanteric T score in two observers while other variable parameters failed to reach the significance level. Even though we found reasonable intraobserver agreement assessment of SI is highly subjective and interobserver agreement is generally poor. Moreover, using digital radiography could not improve correlation with DXA measurements.

Cortical perfusion and local fat occlusion after intramedullary nailing of the ovine tibia--comparison of different surgical procedures.

UNLABELLED: The aim of this study was to determine whether reamed or unreamed nailing is more harmful to local bone perfusion and increases fat occlusion of transcortical vessels. METHODS: After creating a standard fracture of the sheep tibia, reaming was performed in the first group using an experimental optimised reaming system (RE), in the second group with the conventional AO reamer (RC). Unreamed nailing was performed in the third group (UN). UHN 7.5mm titanium was inserted in all three groups. Intramedullary pressure was measured intraoperatively. Quantitative histological analyses of the bone were performed postoperatively. RESULTS: The highest fat occlusion of transcortical vessels occurred in UN (5.7%), the lowest in RE (1.6%). The least harm to intracortical circulation was caused by RE with 28% perfused intracortical vessels compared to 17% (UN) and 18% (RC). CONCLUSION: The experimental optimised reaming system reduces circulatory disturbance and local fat occlusion compared to the existing nailing procedures.

Prognostic factors in nonoperative therapy for chronic symptomatic calcific tendinitis of the shoulder.

OBJECTIVE: To define prognostic factors in chronically symptomatic patients with calcific tendinitis of the shoulder. METHODS: We evaluated 420 patients (488 shoulders) in the context of a prospective cohort study. Epidemiologic data were assessed. The radiographic and sonographic appearance of the calcific deposits was classified. The mean period of nonoperative therapy was 4.4 years (range 0.5-13.7 years). After referral to our institution, standardized nonoperative therapy was continued for a minimum of 3 months. Failure of nonoperative therapy was defined as the persistence of symptomatic calcific tendinitis of the shoulder after a minimum of 6 months. Prognostic factors (determined at P < 0.05 by chi-square test) were analyzed by logistic regression. RESULTS: Of the 420 patients, 269 (64%) were women, 151 (36%) were men. The mean age of the patients was 51.3 years (range 28-84 years). Occurrence of calcific tendinitis of the shoulder was unilateral in 84% and bilateral in 16%. Gärtner type I calcific deposits were found in 37%, type II in 32%, and type III in 31%. Failure of nonoperative therapy was observed in 114 patients (27%). Negative prognostic factors were bilateral occurrence of calcific tendinitis of the shoulder, localization to the anterior portion of the acromion, medial (subacromial) extension, and high volume of the calcific deposit. Positive prognostic factors were a Gärtner type III deposit and a lack of sonographic sound extinction of the calcific deposit. CONCLUSION: Our findings demonstrate the existence of prognostic factors in the nonoperative treatment of chronic symptomatic calcific tendinitis of the shoulder. Guidelines for optimal treatment can be implemented according to these factors to avoid a long-term symptomatic disease course.