10-year follow-up of the Columbus knee prostheses system in a prospective multicenter study.

INTRODUCTION: As endpoint of a prospective multicenter 10-year documentation using the Columbus system, this evaluation carried out results of clinical scores (Knee Society Score and Oxford Knee Score), an evaluation of radiological imaging, survival rates and a collection of complication statistics. MATERIALS AND METHODS: There was a multicenter prospective recruitment of consecutive patients with the indication for total knee replacement (TKR). Preoperatively and 10 years after implantation, clinical scores, range of motion and radiological imaging was performed. During this period, a detailed documentation of complications was made. RESULTS: A total of 210 patients were recruited in 5 centers. 140 patients were available for endpoint examination 10 years after surgery. A survival rate of 96.6% (CI 95%) for the implanted Columbus prostheses after 10 years was demonstrated. Cumulative KSS showed an improvement of 75.3 (± 38.1) points and was highly significant (p < 0.0001, t test). The average functional improvement in the Oxford score was 20.6 (± 9.5) points and was also highly significant (p < 0.0001). The ROM improved from 106.5° (± 20.5) preoperatively to 116.0° (± 11.5) (p < 0.0001, t test). There were no implant-related complications as well as no new complication documented between 5- and 10-year follow-up. CONCLUSIONS: The endpoint analysis after an observation period of 10 years provided good clinical and radiographic results. In particular, an excellent survival rate of 96.6% after 10 years was demonstrated. The data published in this study are the first to be available in a prospective multicenter study on this system, which leads to a high level of clinical significance.

Heterogeneity of penicillin-non-susceptible group B streptococci isolated from a single patient in Germany.

OBJECTIVES: Streptococcus agalactiae [group B streptococci (GBS)] have been considered uniformly susceptible to penicillin. However, increasing reports from Asia and North America are documenting penicillin-non-susceptible GBS (PRGBS) with mutations in pbp genes. Here we report, to the best of our knowledge, the first two PRGBS isolates recovered in Europe (AC-13238-1 and AC-13238-2), isolated from the same patient. METHODS: Two different colony morphologies of GBS were noted from a surgical abscess drainage sample. Both were serotyped and antimicrobial susceptibility testing was performed by different methodologies. High-throughput sequencing was done to compare the isolates at the genomic level, to identify their capsular type and ST, to evaluate mutations in the pbp genes and to compare the isolates with the genomes of other PRGBS isolates sharing the same serotype and ST. RESULTS: Isolates AC-13238-1 and AC-13238-2 presented MICs above the EUCAST and CLSI breakpoints for penicillin susceptibility. Both shared the capsular type Ia operon and ST23. Genomic analysis uncovered differences between the two isolates in seven genes, including altered pbp genes. Deduced amino acid sequences revealed critical substitutions in PBP2X in both isolates. Comparison with serotype Ia clonal complex 23 PRGBS from the USA reinforced the similarity between AC-13238-1 and AC-13238-2, and their divergence from the US strains. CONCLUSIONS: Our results support the in-host evolution of ß-lactam-resistant GBS, with two PRGBS variants being isolated from one patient.

Correct Assessment of Acetabular Component Orientation in Total Hip Arthroplasty From Plane Radiographs.

BACKGROUND: Correct positioning of the cup is an important factor in total hip arthroplasty. Assessing its position from a plain anteroposterior pelvic radiograph is known to be hampered by systemic errors. This study focuses on developing a correction method to adjust for these potential sources of error and to eliminate them based on a 3D geometric analysis. METHODS: Computed tomography scans of 113 (66 male, 47 female) pelvices were reconstructed and virtually projected onto a plain radiograph with varying rotational and translational positions. Thus cup inclination and anteversion as measured on a 2D-radiograph and in the 3D environment were correlated. Projected offset of the symphysis from the mid-sacrum served as a mean to measure pelvic right/left-rotation. Pelvic tilt was determined from the projected height of the contour of the small pelvis. Correction formulas were verified by projecting a gimbal-mounted artificial pelvis with a cup implanted in a known position. RESULTS: We found gender-specific formulas that correct for malrotated and off-centered radiographs. Applying these formulas cup inclination was assessed as close as 1.3° (±1.90°) to the true 3D value and cup anteversion as close as 1° (±1.91°) although deviations between directly measured plain values and corrected values rose up to 18°. CONCLUSION: Inherent effects of central projection and malrotations due to pelvic tilt, pelvic rotation, and noncentered radiographs are corrected. Evaluation of radiographic inclination and anteversion of acetabular cups from plain 2D-radiographs show improved precision. Real values are approached better than 1.3° when applying our correction formulas.

[5-year follow-up of 210 Columbus knee prostheses : A prospective multicentre study]. / 5-Jahres-Follow-up von 210 Columbus-Knietotalendoprothesen : Eine prospektive multizentrische Studie.

INTRODUCTION: As part of 10-year documentation using the Columbus system, the interim evaluation was carried out 5 years after implantation with a collection of clinical scores, evaluation of radiological imaging and collection of statistics concerning complications. METHODS: There was a multicentre prospective recruitment of consecutive patients with the indication of implantation of a surface replacement prosthesis (Columbus CR, Deep Dish fixed inlay). Preoperatively, clinical scores were recorded (KSS and Oxford score). Five years postoperatively a new evaluation of clinical scores, the range of motion (ROM) and a radiological check-up including full leg imaging under load was performed. During this period, detailed complication documentation was made. RESULTS: A total of 210 patients were recruited in five centres. 187 patients were available for examination 5 years after surgery. Cumulative KSS increased from 87.5 (±26.6) preoperatively to 170 (±29.1) 5 years postoperatively. The cumulative KSS improvement was 81.5 (±35.2) points and was highly significant (p < 0.0001; t­test). The average functional improvement in the Oxford score between the preoperative and 5­year follow-up was 21.7 (±8.8) points and was also highly significant (p < 0.0001). The ROM improved from 106.3° (±20.2) preoperatively to 114.0° (±12.1) 5 years postoperatively (p < 0.0001; t test). Five years after implantation, the average mechanical leg axis was 178.0° (±2.1). There was no clinically apparent or native radiologic visible aseptic loosening of the femoral or tibial joint component. There were 33 complications, but no implant-related complications such as inlay dislocation, material fracture or aseptic loosening. In total, 6 revision surgeries were performed during the follow-up period, which corresponds to a survival rate of 97.1% (CI 95%) for the implanted Columbus knee in the present patient collective for 5 years. CONCLUSION: The interim analysis at 5 years of long-term observation of the Columbus system provided good clinical and radiographic results.

Factors influencing treatment success of negative pressure wound therapy in patients with postoperative infections after Osteosynthetic fracture fixation.

BACKGROUND: Negative Pressure Wound Therapy (NPWT) is being increasingly used to treat postoperative infections after osteosynthetic fracture fixation. The aim of the present study was to analyze the influence of epidemiological and microbiological parameters on outcome. METHODS: Infections following operative fracture fixation were registered in a comprehensive Critical Incidence Reporting System and subsequently analyzed retrospectively for characteristics of patients including comorbidity, bacteria, and clinical factors. The influence of the investigated parameters was analyzed using logistic regression models based on data from 106 patients. RESULTS: Staged wound lavage in combination with NPWT allowed implant preservation in 44% and led to successful healing in 73% of patients. Fermentation characteristics, load and behavior after gram staining revealed no statistically significant correlation with either healing or implant preservation. Infecting bacteria were successfully isolated in 87% of patients. 20% of all infections were caused by bacterial combinations. We observed a change in the infecting bacterial species under therapy in 23%. Age, gender, metabolic diseases or comorbidities did not influence the probability of implant preservation or healing. The delayed manifestation of infection (>4 weeks) correlated with a higher risk for implant loss (OR 5.1 [95% CI 1.41-17.92]) as did the presence of bacterial mixture (OR 5.0 [95% CI 1.41-17.92]) and open soft-tissue damage ≥ grade 3 (OR 10.2 [CI 1.88-55.28]). Wounds were less likely to heal in conjunction with high CRP blood levels (>20 mg/l) at the time of discharge (OR 3.6 [95% CI 1.31-10.08]) or following a change of the infecting bacterial species under therapy (OR 3.2 [95% CI, 1.13-8.99]). CONCLUSIONS: These results indicate that the delayed manifestation of infection, high CRP blood levels at discharge, and alterations in the infecting bacterial species under therapy raise the risk of NPWT failure.

Osteoarthritic changes rather than age predict outcome following arthroscopic treatment of femoroacetabular impingement in middle-aged patients.

BACKGROUND: Our purpose was to evaluate outcome following arthroscopic treatment of femoroacetabular impingement (FAI) in middle-aged patients and to define risk factors for conversion to total hip arthroplasty (THA). METHODS: This was a retrospective case series of 79 consecutive patients (40 to 65 years) undergoing arthroscopic treatment of FAI (follow-up ≥12 months). Outcome at follow-up was assessed using Hip outcome score (HOS). Alpha angle, Kellgren Lawrence grade (K-L grade), joint space width (JS), lateral center edge (LCE) angle, caput-collum-diaphysis (CCD) angle and acetabular index (AI) were analysed retrospectively. THA group and Non-THA group were compared. RESULTS: Seventy-nine patients (mean age 48.6 years, mean follow-up 32 months) were included. 18 patients (22.8 %) were converted to THA. Mean HOS score in the Non-THA group at time point of follow-up was 80.2. Non-THA group and THA group showed no significant differences for mean age (48.2 years vs. 49.9 years, p = 0.278), alpha angel (p = 0.541), LCE (p = 0.294), CCD (p = 0.101) and AI (p = 0.661) in contrast to differences for JS (p = <0.001) and K-L grade (p = <0.001). Risk of conversion to THA was higher for patients with K-L grade 3 (p = 0.003) or joint space less or equal 2 mm (p = 0.001). CONCLUSIONS: One fifth of the middle-aged patients required early conversion to THA. Advanced JS narrowing and K-L grade rather than age alone can be considered as risk factor for conversion to THA.

Diagnosis of prosthetic joint infections using UMD-Universal Kit and the automated multiplex-PCR Unyvero i60 ITI(®) cartridge system: a pilot study.

BACKGROUND: Prosthetic joint infections (PJI) are associated with high morbidity and costs. Various efforts have been made to improve the diagnosis of PJI over the past years, but only few studies have assessed the diagnostic utility of nucleic acid amplification test (NAAT) techniques in this context. Here, we report our experience with a commercial 16S rRNA gene PCR and an automated multiplex-PCR cartridge system in identifying pathogens causing PJI. MATERIALS AND METHODS: A prospective single-centre study was performed including 54 patients with either septic or aseptic prosthetic joint replacement or surgical revision between February 2012 and April 2013. Conventional cultures of periprosthetic tissue samples were compared with the results of broad-range 16S rRNA gene real-time PCR (UMD-Universal Pathogen DNA Extraction and PCR Analysis, Molzym GmbH, Germany) and the multiplex-PCR Unyvero ITI(®) cartridge system (U-ITI; Curetis AG, Germany). Conventional culture and broad-range 16S rRNA gene real-time PCR were performed on all samples. U-ITI was used in a subgroup of 28 cases including all culture-positive cases. The agreement of the results from the methods was assessed. RESULTS: Of 54 cases, seven were culture-positive. Broad-range 16S rRNA gene real-time PCR gave 6, U-ITI 3 concordant positive results. Of the 47 culture-negative samples, 46 were also negative by broad-range 16S rRNA gene real-time PCR resulting in a 96 % (52/54) agreement between 16S rRNA gene PCR and culture. Of the 21 culture-negative samples analysed with U-ITI, 20 gave negative results, including the single 16S rRNA gene PCR-positive/culture-negative specimen. The rate of agreement between U-ITI and culture results was 82 % (23/28). CONCLUSION: This pilot study gave no indication of superiority of the used NAATs over conventional culture methods for the microbiological diagnosis of PJI. Drawbacks are susceptibility to contamination in the case of 16S rRNA gene real-time PCR, labour-intensive DNA extraction and limited pathogen panel in the case of the multiplex cartridge PCR system. More prospective trials are needed to evaluate the diagnostic performance of NAATs and their impact on the clinical management of PJI.

Digital templating in total knee and hip replacement: an analysis of planning accuracy.

PURPOSE: The aim of this study was to determine how well pre-operative size selection for total knee and hip arthroplasties based on the digital imaging with and without additional referencing correlated with the size actually implanted. METHODS: Size selection planning of total knee arthroplasty by digital templating was documented in 46 cases with reference ball (group A) and in 48 cases without ball (group B). In addition, prospective analysis of pre-operative planning was conducted for 52 acetabular components with reference ball (group C) and 69 without ball (group D) as well as stem planning in 38 cases with ball (group E) and 54 cases without ball (group F). The data were analysed and compared with the size of the final component selected during surgery. RESULTS: The correlation between planned and implanted size for total knee arthroplasty in group A resulted in femoral anteroposterior (AP) r = 0.8622 and lateral r = 0.8333 and in group B AP r = 0.4552 and lateral r = 0.6950. Tibial in group A was AP r = 0.9030 and lateral r = 0.9074 and in group B AP r = 0.7000 and lateral r = 0.6376. For the acetabular components, the results in group C were r = 0.5998 and group D r = 0.6923. For stems, group E was r = 0.5306 and group F r = 0.5786. No correlation between BMI and the difference between planned and implanted size was found in any of the groups. CONCLUSION: In the case of total hip arthroplasty there was a relatively low correlation between planned and implanted sizes with or without reference ball. For total knee arthroplasties the already high precision of size planning was further improved by the additional referencing with a reference ball.

Periprosthetic joint infection--effect on quality of life.

PURPOSE: Relatively little is known about the extent to which periprosthetic joint infections (PJI) affect the patient's long-term quality of life (QoL). Our study aim was to assess the effect of a periprosthetic infection on our patients' QoL. METHODS: We collected data retrospectively of patients who had undergone surgery in our institution between 2006 and 2011. To capture their overall QoL, we telephoned the patients who could be reached and asked them the questions on the SF-12 questionnaire. RESULTS: In 84 patients (53 male, 31 female, 43 TKA and 41 THA), 88 % of the hip infections and 62 % of the knee infections had been successfully treated. The hip infections' cure rate was significantly higher than that of the knee joint infections. The average SF-12 score was 36.2 points on the physical scale and 52 on the mental scale. The difference in QoL between patients with and without successful infection therapy was not significant, nor did the site of the infection (knee or hip) influence QoL significantly. Comparison of our patients' QoL data to that from the general population revealed a significant difference in the physical scale but not the mental scale. CONCLUSION: From these results QoL is substantially reduced after a prosthetic infection. We did however observe that post-Girdelstone procedure patients or those with an arthrodesis attained an acceptable QoL, and that those methods remain therapeutic alternatives as far as patient-perceived QoL is concerned.

Rotational limb alignment changes following total knee arthroplasty.

PURPOSE: The aim of the present study was to assess the changes in rotational alignment introduced by total knee arthroplasty (TKA) and the reproducibility of pre- and postoperative CT measurements of rotational limb alignment. METHODS: For this purpose we analyzed data from 196 consecutive cruciate-retaining, fixed bearing Columbus TKA procedures. Both pre- and postoperative scans torsion difference CT scans were available for measurements in 89 cases. Using these CT scans the neck-malleolar angle (NMA), the femoral posterior condylar angle (fPCA), the tibial posterior condylar axis (tPCA) and the tibial torsion angle (TTA) were independently assessed by three raters. CT scans were re-evaluated 8 weeks later by the most experienced rater for assessment of intraobserver agreement. RESULTS: Measurements of all angles were prone to high standard deviations reflecting interindividual variability. Mean fPCA changed from 1.3° to 2.7° internal rotation preoperatively to 0.1°-1.9° internal rotation postoperatively. Based on a relative external rotation of the tibial base plate as compared to the preoperative situation, we found a relative internal rotation of the postoperative NMA and tibial torsion of 3°-5.4° and 6°-7.5°, respectively. Intra- and interobserver agreement was strong for all angles assessed (ICCs 0.7-1.0) except for fPCA (ICC 0.2-0.6). However, mean absolute measurement differences for fPCA were clinically acceptable (1.2°-2.6°). CONCLUSIONS: Reproducibility of CT rotational limb alignment measurements was found to be clinically acceptable. Rotational alignment of the femoral and even more so of the tibial component will ultimately affect the rotational alignment of the entire limb-at least when fixed bearings are used. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Modular sleeves with ceramic heads in isolated acetabular cup revision in younger patients-laboratory and experimental analysis of suitability and clinical outcomes.

PURPOSE: One possibility in hip arthroplasty revisions is to combine a modular ceramic head with an adapter or sleeve in isolated acetabular cup replacement. This study consisted of an experimental part to analyse the reliability of taper damage predictions, and a clinical part to analyse the outcomes of modular ceramic head implantation in a case series of isolated cup replacements. METHODS: Analysis of scratch size on 11 explanted hip stems were examined macroscopically and by stereomicroscopy to classify damage to the conical taper. The second part consisted of a prospective analysis of isolated cup revisions using a modular ceramic head, performed in two orthopedic centres. RESULTS: Analysis of scratch size on the taper yielded inter-observer correlations of 0.545-0.909; comparison with stereomicroscopic data recordings yielded a moderate correlation, with values between 0.545 and 0.090. The clinical study included 47 isolated acetabular cup revisions involving modular ceramic heads. Ceramic head failure did not occur during the average clinical and radiological observation period of 26 months. Mean Harris Hip Score (HHS) at follow-up was 70 points. CONCLUSION: From these results, it can be concluded that damage to the implanted stem taper cannot be reliably predicted intraoperatively. Nevertheless, the clinical outcomes did show that there were no problems with the ceramic heads over the short observation period. The application of modular ceramic heads in younger patients requiring isolated cup replacement requires proper risk-benefit analysis, but is possible and appears to be a safe procedure.

Towards the simulation of bone-implant systems with a stratified material model.

BACKGROUND: The clinical performance of medical devices is becoming increasingly important for the requirements of modern development processes and the associated regulations. However, the evidence for this performance can often only be obtained very late in the development process via clinical trials or studies. OBJECTIVE: The purpose of the presented work is to show that the simulation of bone-implant systems has advanced in various aspects, including cloud-based execution, Virtual Clinical Trials, and material modeling towards a point where and widespread utilization in healthcare for procedure planning and enhancing practices seems feasible. But this will only hold true if the virtual cohort data build from clinical Computer Tomography data are collected and analysed with care. METHODS: An overview of the principal steps necessary to perform Finite Element Method based structural mechanical simulations of bone-implant systems based on clinical imaging data is presented. Since these data form the baseline for virtual cohort construction, we present an enhancement method to make them more accurate and reliable. RESULTS: The findings of our work comprise the initial step towards a virtual cohort for the evaluation of proximal femur implants. In addition, results of our proposed enhancement methodology for clinical Computer Tomography data that demonstrate the necessity for the usage of multiple image reconstructions are presented. CONCLUSION: Simulation methodologies and pipelines nowadays are mature and have turnaround times that allow for a day-to-day use. However, small changes in the imaging and the preprocessing of data can have a significant impact on the obtaind results. Consequently, first steps towards virtual clinical trials, like collecting bone samples, are done, but the reliability of the input data remains subject to further research and development.

Effects of muscle-equivalent forces on the biomechanical behavior of proximal femur fracture models: a pilot study on artificial bones.

INTRODUCTION: There has been extensive analysis of the influence of muscle forces and their effects on the biomechanical behavior of the proximal femur. Nevertheless, these forces have only been taken into account in a handful of biomechanical studies in the field of traumatology. The aim of this study was to analyze the biomechanical behavior of two typical fracture models of the proximal femur based on muscle-equivalent forces. METHOD: Plate osteosynthesis was performed on two groups of artificial femora to stabilize either a trochanteric osteotomy (n= 5) or a femur shaft osteotomy (n = 5). After fixation axial loading was applied to the constructs first without muscle-equivalent forces and then with the addition of these forces (abductor groups and vastus lateralis). Displacement at the osteotomy site and the stiffness of the whole construct were measured during loading. RESULTS: Comparison of the two loading modes revealed no significant differences for displacement or stiffness for the trochanteric fractures. For the femur shaft fractures, a significant difference was found for displacement (p = 0.023) and stiffness (p = 0.003) with or without muscle-equivalent forces. CONCLUSION: The loading protocol for implant testing on femur shaft fractures should include muscle-equivalent forces. For trochanteric fractures, consideration of muscle forces is not entirely necessary since they will have little effect on the results, for example, when comparing implants.

High complication rate after biplanar open wedge high tibial osteotomy stabilized with a new spacer plate (Position HTO plate) without bone substitute.

PURPOSE: We performed a prospective clinical and radiographic evaluation after open wedge high tibial osteotomy (HTO) using the new Position HTO plate (Aesculap, Tuttlingen, Germany) without bone transplantation. METHODS: Thirty-five open wedge HTOs with the Position HTO plate were performed without bone wedges. The mean patient age was 44.6 ± 9.2 years at the time of osteotomy, which was planned with mediCAD II software (Hectec, Niederviehbach, Germany). The Hospital for Special Surgery score, Lysholm-Gillquist score, Tegner activity level, and International Knee Documentation Committee subjective score were used for clinical assessment. We evaluated radiographs obtained preoperatively and at 2, 6, and 12 months postoperatively using full-weight-bearing anteroposterior whole-leg views and anteroposterior and lateral views of the knee. For statistical analyses, JMP 8.0.1 (SAS, Cary, NC) was used. RESULTS: We observed an overall complication rate of 34% and a plate-related complication rate of 23%. Plate-related complications included loss of correction, fracture of the tibial plateau, screw failure, malunion, and fracture of the lateral cortical bone. A significant difference in the mechanical tibiofemoral angle of -1.3° ± 1.4° (P < .001) was found between the follow-up at 2 and 6 months. The mean Hospital for Special Surgery score was 74.8 ± 11.7 preoperatively, and it increased to 87.8 ± 11.0 (P < .001). The mean score on the Lysholm-Gillquist knee functional scoring scale was 55.5 ± 21.7 preoperatively, and it improved to 73.0 ± 23.9 (P < .001). The Tegner activity level was 2.6 ± 0.9 preoperatively, and it improved significantly at final follow-up to 3.7 ± 1.8 (P < .02). The International Knee Documentation Committee subjective score was 43.0 ± 14.9 preoperatively, and it increased to 66.1 ± 21 (P < .001). CONCLUSIONS: We have shown a high plate-related complication rate and a significant loss of correction between 2 and 6 months of follow-up after open wedge HTO using the new Position HTO plate without bone wedges. The preoperatively planned mechanical tibiofemoral angle was not achieved. Despite these complications, the clinical outcome improved significantly. The Position HTO plate cannot be recommended with the presented technique. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Does the extent of prebending affect the stability of femoral shaft fractures stabilized by titanium elastic nails? A biomechanical investigation on an adolescent femur model.

BACKGROUND: Elastic stable intramedullary nailing (ESIN) is a common procedure for stabilization of femoral shaft fractures in childhood. Prebending of the nail is generally recommended to achieve optimal nail tension at the fracture site. To our knowledge there are no published data on the effects of prebending on stability. The purpose of this biomechanical study was to compare the effects of different degrees of prebending on the stability of transverse femoral fractures after ESIN using a bone model. METHODS: Standardized transverse midshaft fractures were created in 20 synthetic, biomechanically validated adolescent bones (4th Generation Composite Femur--Sawbones Europe AB, Sweden) that were stabilized with 2 titanium nails (TEN) each (4 mm diameter, Synthes) and inserted in standardized retrograde technique. The 4 test series addressed nail prebending at 0 degree, 30 degrees, 45 degrees, and 60 degrees. The models were tested biomechanically in 4-point bending in the coronal and sagittal planes, relative stiffness was determined and analyzed statistically. The level of significance was set at P < 0.05. RESULTS: Comparison of the individual groups showed no significant differences in stiffness for different degrees of prebending in the coronal plane. Significantly reduced stiffness was found in the sagittal plane for the group with 60-degree prebending compared with the 0-degree, 30-degree, and 45-degree prebending groups. Intragroup comparison in the coronal and sagittal planes yielded a significantly reduced stiffness in the sagittal plane compared with the coronal plane in the group with 60-degree prebending. The 45-degree prebending group showed a similar tendency and in the 0-degree and 30-degree prebending groups there were no significant differences. CONCLUSIONS: On a synthetic bone model, prebending of TEN was found to affect the stability of transverse fractures of the femoral shaft, whereby indiscriminate prebending will reduce stability in the sagittal plane.Despite limited extrapolation of the findings to the in vivo situation, it can be stated that prebending of TEN by 0 to 30 degrees offers the greatest stability in the coronal and sagittal planes for transverse fractures of the femoral shaft.

Internal fixation of dorsally comminuted fractures of the distal part of the radius: a biomechanical analysis of volar plate and intramedullary nail fracture stability.

INTRODUCTION: The purpose of the present study was to carry out biomechanical testing of "new generation" volar plates and an intramedullary nail. METHODS: Four volar locking plates (Column Plate, VariAx distal radius, 2.4 mm-LCP and 3.5 mm-LCP) and the intramedullary nail, Targon-DR, were implanted in biomechanically validated artificial bones after simulation of a wedge osteotomy with total transection of the volar cortex to mimic a type 23 A3-fracture according to the AO-classification. Axial load (250 Newton [N]) and volar and dorsal bending loads (both 50 N) were applied. Axial load was increased to fixation failure. Gap motion was measured three-dimensionally directly at the fracture gap. The 3.5 mm-LCP was used for comparison as it currently represents an established locking implant that has been well tested biomechanically. RESULTS: In this experimental setting, the 2.4 mm-LCP showed the lowest resistance under all three loading modi and, consequently, the highest level of motion at the osteotomy gap in comparison to all other implants (p < 0.05). Under axial loading, there were no significant differences between the other four implants. Under dorsal bending, the Targon-DR-nail and the VariAx-plate showed less gap displacement in comparison to the 3.5 mm-LCP (p < 0.05). Under volar bending, only the Targon-nail showed greater resistance than the 3.5 mm-LCP (p < 0.05) with no other significant differences between the Column Plate, the VariAx and the 3.5 mm-LCP. CONCLUSION: In this experimental setting, all "new generation" implants for distal radius fractures with the exception of the 2.4 mm-LCP showed identical or higher stability compared to the 3.5 mm-LCP. The 2.4 mm-LCP showed the lowest resistance and this must be taken into consideration when planning postoperative functional therapy.

Dual-energy CT virtual noncalcium technique: detecting posttraumatic bone marrow lesions--feasibility study.

PURPOSE: To evaluate traumatized bone marrow with a dual-energy (DE) computed tomographic (CT) virtual noncalcium technique. MATERIALS AND METHODS: In this prospective institutional review board-approved study, 21 patients with an acute knee trauma underwent DE CT and magnetic resonance (MR) imaging. A software application was used to virtually subtract calcium from the images. Presence of fractures was noted, and presence of bone bruise was rated on a four-point scale for six femoral and tibial regions by two radiologists. CT numbers were obtained in the same regions. Consensus reading of independently read MR images served as the reference standard. Image ratings and CT numbers were subjected to receiver operating characteristic curve analysis. RESULTS: After exclusion of 16 regions owing to artifacts, MR imaging revealed 59 bone bruises in the remaining 236 regions (19 of 114 femoral, 40 of 122 tibial). Fractures were present in eight patients. Visual rating revealed areas under the curve of 0.886 and 0.897 in the femur and 0.974 and 0.953 in the tibia for observers 1 and 2, respectively. For CT numbers, the respective areas under the curve were 0.922 and 0.974. If scores of 1 and 2 (strong or mild bone bruise) were counted as positive, sensitivities were 86.4% and 86.4% and specificities were 94.4% and 95.5% for observers 1 and 2, respectively. The kappa statistic demonstrated good to excellent agreement (femur, kappa = 0.78; tibia, kappa = 0.87). CONCLUSION: This DE CT virtual noncalcium technique can subtract calcium from cancellous bone, allowing bone marrow assessment and potentially making posttraumatic bone bruises of the knee detectable with CT.

Effect of proximal humeral fractures on the age-specific prevalence of rotator cuff tears.

BACKGROUND: This study examined the effect of proximal humeral fractures on the age- and shoulder-specific prevalence of rotator cuff tears (RCTs) as well as the association with fracture severity, patient age, and clinical outcome. METHODS: Sixty-three fractures were treated conservatively; in 114 cases, minimally invasive osteosynthesis, and in 125 cases, open reduction and plate fixation were performed without rotator cuff reconstruction. After 4.4 years, all 302 patients were clinically and sonographically examined. RESULTS: We examined 139 two-part, 95 three-part, and 68 four-part fractures according to Neer and 134 A, 86 B, and 82 C fractures according to the AO classification. There were 52 patients (17%) with a complete rotator tear (RCT) only at the injured shoulder and 11 patients (4%) with a complete RCT only at the contralateral shoulder (p < 0.0001). Independent of the patient's age at follow-up, the prevalence of an RCT in the fractured shoulder was 13% higher than the prevalence in the opposite shoulder. Four-part fractures showed a significant association with a complete RCT (p = 0.047).Of 74 patients with a satisfactory or poor Constant Score, 33 (44.6%) had RCTs. In the remaining 228 patients with a good to excellent result, only 26 (11.4%) had RCTs. We showed that 66% of the RCTs observed at the fractured shoulder were caused by trauma. There was no association between treatment modality and a complete RCT. CONCLUSION: RCTs may need special attention in initial diagnostics, management, and follow-up especially in severe proximal humeral fractures.

Correlation of radiographic and navigated measurements of TKA limb alignment: a matter of time?

Valid and reproducible measurements of limb alignment are prerequisites for planning, performing and evaluating TKAs. Although navigation systems have been shown to be reproducible tool for intraoperative TKA alignment measurements, particular doubt has been raised on the correlation with postoperative radiographic measurements. The aim of the present study was to evaluate whether the association of postoperative radiographic and navigation measurements of limb alignment was dependent on the time of acquisition. For this purpose, we retrospectively compared two groups of patients who underwent computer-assisted cemented TKA for osteoarthritis of the knee. Intraoperative navigation measurements (OrthoPilot™, Aesculap, Tuttlingen, Germany) were recorded before any cuts were made and again after implants had been placed. Long leg standing radiographs were acquired preoperatively in both the groups and either 2 weeks or 3 months postoperatively and AP limb alignment measurements were correlated with those of the respective navigation assessments. Preoperative deformity was similar in both the groups and correlation between radiographic and navigation measurements was excellent in both groups (ρ = 0.845 and 0.945, respectively). However, both mean and maximum discrepancies between radiographic and navigation measurements of leg alignment were significantly larger when radiographs were obtained 2 weeks (2.6° ± 2.1°, max. 10°) when compared with 3 months (1.8° ± 1.4°, max. 5°) postoperatively (P = 0.026). Accordingly, correlation between radiographic and navigation measurements was poor when radiographs were obtained 2 weeks postoperatively (ρ = 0.26, n.s.) but in the range of preoperative assessments when obtained 3 months postoperatively (ρ = 0.841, P < 0.001). Radiographic and navigation measurements of TKA limb alignment correlate well preoperatively. Equally good correlations can only be achieved when postoperative radiographic measurements are delayed to a time when more patients achieve full or near-full extension and are able to bear full weight leading to more valid radiographs.