Tibial and femoral osteotomies in varus deformities - radiological and clinical outcome.

BACKGROUND: Varus deformities of the knee are frequently corrected by osteotomies, which should be performed at the level of origin. But in contrast to high tibial osteotomies (HTO), little data exists for distal femoral osteotomies (DFO). This study evaluates radiological and clinical outcomes after valgisation osteotomies in the proximal tibia and distal femur. METHODS: We used an observational cohort study design and prospectively performed preoperative long standing radiographs (LSR), lateral x-rays and clinical questionnaires (SF-36, Lysholm score, VAS). Postoperative LSR and lateral x-rays were obtained on average 18 months postoperative and postoperative clinical questionnaires at final visit (mean follow up 46 months). A subgroup analysis of the different surgical techniques (oHTO vs. cDFO) was performed, with regards to radiological and clinical outcomes. RESULTS: Finally 28 osteotomies with medial tibial opening (oHTO) or lateral femoral closing (cDFO) wedge osteotomies in 25 consecutive patients (mean age 40 years) were identified. There were 17 tibal and 11 femoral procedures. All osteotomies were performed at the origin of deformity, which was of different etiology. The average deviation of the final HKA compared to the preoperative planning was 2.4° ± 0.4°. Overall, there was a significant improvement in all clinical scores (SF-36: 61.8 to 79.4, p < 0.001; Lysholm-score: 72.7 to 90.4, p < 0.001; VAS: 3 to 1, p < 0.001). There was no significant correlation between surgical accuracy and outcome scores. CONCLUSION: Valgisation osteotomies lead to a significant improvement in all clinical scores with the demonstrated treatment protocol. An appreciable proportion of varus deformities are of femoral origin. Since cDFO provides comparable radiological and clinical results as oHTO, this is an important treatment option for varus deformities of femoral origin.

Mice Lacking the Matrilin Family of Extracellular Matrix Proteins Develop Mild Skeletal Abnormalities and Are Susceptible to Age-Associated Osteoarthritis.

Matrilins (MATN1, MATN2, MATN3 and MATN4) are adaptor proteins of the cartilage extracellular matrix (ECM), which bridge the collagen II and proteoglycan networks. In humans, dominant-negative mutations in MATN3 lead to various forms of mild chondrodysplasias. However, single or double matrilin knockout mice generated previously in our laboratory do not show an overt skeletal phenotype, suggesting compensation among the matrilin family members. The aim of our study was to establish a mouse line, which lacks all four matrilins and analyze the consequence of matrilin deficiency on endochondral bone formation and cartilage function. Matn1-4-/- mice were viable and fertile, and showed a lumbosacral transition phenotype characterized by the sacralization of the sixth lumbar vertebra. The development of the appendicular skeleton, the structure of the growth plate, chondrocyte differentiation, proliferation, and survival were normal in mutant mice. Biochemical analysis of knee cartilage demonstrated moderate alterations in the extractability of the binding partners of matrilins in Matn1-4-/- mice. Atomic force microscopy (AFM) revealed comparable compressive stiffness but higher collagen fiber diameters in the growth plate cartilage of quadruple mutant compared to wild-type mice. Importantly, Matn1-4-/- mice developed more severe spontaneous osteoarthritis at the age of 18 months, which was accompanied by changes in the biomechanical properties of the articular cartilage. Interestingly, Matn4-/- mice also developed age-associated osteoarthritis suggesting a crucial role of MATN4 in maintaining the stability of the articular cartilage. Collectively, our data provide evidence that matrilins are important to protect articular cartilage from deterioration and are involved in the specification of the vertebral column.

Cancellous allogenic and autologous bone grafting ensure comparable tunnel filling results in two-staged revision ACL surgery.

OBJECTIVES: Patients with recurrent instability after anterior cruciate ligament (ACL) reconstruction often present with enlarged or misplaced tunnels and bone grafting is required prior to the actual revision reconstruction. Autologous bone grafting features limited quantity and donor site morbidity. These problems may be eliminated utilizing cancellous bone allografts, but their efficiency and reliability have not been investigated systematically. The aim of the present study was to compare tunnel filling rates attained by utilizing either allogenic or autologous cancellous bone grafts. MATERIALS AND METHODS: A total of 103 consecutive patients were enrolled retrospectively. All patients suffered from recurrent instability and underwent either allogenic or autologous cancellous bone grafting. Computed tomography (CT) was carried out before and after the bone grafting procedure. Based on preoperative CT scans, positioning and maximum diameter of the femoral and tibial tunnels were determined. Tunnel filling rates were calculated as a ratio of pre- and postoperative tunnel volumes. Primary outcome was the tibial tunnel filling rate. Femoral filling rates and density of the grafted bone were assessed secondarily. RESULTS: Preoperative CT scans revealed no significant differences between the two groups regarding distribution of misplacement and widening of the femoral or tibial tunnel. Postoperative CT scans were conducted after an interval of 5.2 months. Tunnel filling rates of 74.5% (± 14.3) femoral and 85.3% (± 10.3) tibial were achieved in the allogenic compared to 74.3% (± 15.9) femoral and 84.9% (± 9.4) tibial in the autologous group. With p values of 0.85 at the femur and 0.83 at the tibia, there were no significant differences between the groups. The density of the grafted bone revealed significantly higher values in the allogenic group. CONCLUSIONS: Utilizing cancellous bone allografts in two-staged revision ACL surgery provides for sufficient and reproducible filling of enlarged or misplaced tunnels. The filling rates are comparable to those achieved with autologous bone grafting. Advantages of allografts are the unrestricted quantity and the absence of any harvesting procedure.

The value of elbow arthroscopy in diagnosing and treatment of radial head fractures.

BACKGROUND: Surgical treatment of radial head fractures is increasingly performed arthroscopically. These fractures often feature concomitant injuries to the elbow joint, which may be under-diagnosed in the radiological examinations. Little is known about the diagnostic value of arthroscopy, the treatment options that arise from arthroscopically assisted fracture fixation and clinical results. We hypothesized that arthroscopy can detect additional concomitant injuries and simultaneously expands the therapeutic options. Therefore aim of this study was to compare arthroscopic and radiologic findings, to assess the distinct arthroscopic procedures and to follow up on the clinical outcomes. METHODS: Twenty patients with radial head fractures were retrospectively included in two study centers. All patients underwent elbow arthroscopy due to at least one of the following suspected concomitant injuries: osteochondral lesions of the humeral capitellum, injuries of the collateral ligaments or loose joint bodies. Preoperative radiological findings were compared to arthroscopic findings. Afterwards, arthroscopic treatment options and clinical outcomes were assessed. RESULTS: Arthroscopic findings led to revision of the classified fracture type in 70% (p = 0.001) when compared to preoperative conventional radiographs (CR) and in 9% (p = 0.598) when compared to computed tomography (CT) or magnetic resonance imaging (MRI). Diagnosis of loose bodies was missed in 60% (p < 0.001) of the CR and in 18% (p = 0.269) of the CT/MRI scans. Osteochondral lesions were not identified in 94% (p < 0.001) of the CR and in 27% (p = 0.17) of the CT/MRI scans. Percutaneous screw fixation was performed in 65% and partial radial head resection in 10%. Arthroscopy revealed elbow instability in 35%, leading to lateral collateral ligament reconstruction. After a mean follow up of 41.4 ± 3.4 months functional outcome was excellent in all cases (DASH-Score 0.6 ± 0.8; MEPI-Score 98.5 ± 2.4; OES-Score 47.3 ± 1.1). CONCLUSIONS: Elbow arthroscopy has a significant diagnostic value in radial head fractures when compared to standard radiological imaging. Although statistically not significant, arthroscopy also revealed concomitant injuries in patients that presented with an uneventful MRI/CT. Furthermore, all intraarticular findings could be treated arthroscopically allowing for excellent functional outcomes. TRIAL REGISTRATION: Institutional Review Board University of Munich (LMU), Trial Number 507-14.

Augmentation of plate osteosynthesis for proximal humeral fractures: a systematic review of current biomechanical and clinical studies.

INTRODUCTION: Secondary dislocation due to loss of fixation is the most common complication after plate fixation of proximal humeral fractures. A wide range of different techniques for augmentation has been described to improve the primary and secondary stability. Nevertheless, comparative analyses on the specific advantages and limitations are missing. Therefore, the aim of the present article was to systematically review and evaluate the current biomechanical and clinical studies. MATERIALS AND METHODS: The databases of PubMed and EMBASE were comprehensively searched for studies on augmentation techniques for proximal humeral fractures using defined search terms. Subsequently, all articles identified were screened for eligibility and subdivided in either clinical or biomechanical studies. Furthermore, the level of evidence and study quality were assessed according the Oxford Centre for Evidence-Based Medicine and the Coleman Methodology Score, respectively. RESULTS: Out of 2788, 15 biomechanical and 30 clinical studies were included. The most common techniques were structural allogenic or autologous bone grafting to enhance the medial support, metaphyseal void filling utilizing synthetic bone substitutes or bone grafts, and screw-tip augmentation with bone cement. Biomechanical data were available for structural bone grafting to enhance the medial support, void filling with synthetic bone substitutes, as well as for screw-tip augmentation. Clinical evidence ranged from level II-IV and study quality was 26-70/100 points. Only one clinical study was found investigating screw-tip augmentation. All studies included revealed that any kind of augmentation positively enhances mechanical stability, reduces the rate of secondary dislocation, and improves patients' clinical outcome. None of the studies showed relevant augmentation-associated complication rates. CONCLUSIONS: Augmentation of plate fixation for proximal humeral fractures seems to be a reliable and safe procedure. All common techniques mechanically increase the constructs' stability. Clinically evaluated procedures show reduced complication rates and improved patient outcomes. Augmentation techniques seem to have the highest significance in situations of reduced bone mineral density and in high-risk fractures, such as 4-part fractures. However, more high-quality and comparative clinical trials are needed to give evidence-based treatment recommendations.

Functional treatment for fractures to the base of the 5th metatarsal - influence of fracture location and fracture characteristics.

BACKGROUND: Fractures to the base of the fifth metatarsal are common, but their treatment remains controversial. Especially for Lawrence and Botte (L&B) type II fractures, there is conflicting evidence and consequently no consensus. Further, many authors consider displacement, articular involvement, and number of fragments an indication for surgery, although evidence is missing. The aim of this study was to evaluate the outcome of functional treatment for all L&B type I and II fractures. Of special interest were the influence of (1) the fracture location (L&B type I vs. II) and (2) the fracture characteristics (displacement, intra-articular involvement, communition) on the subjective outcome. METHODS: Retrospective registry study with a prospective follow-up. Patients with an acute, isolated, epi-metaphyseal fracture to the fifth metatarsal bone (L&B type I and II) treated by full weightbearing with a minimum follow-up of 6 months were included. Fracture location (L&B type I and II) and characteristics (displacement <2 mm or >2 mm, intra-articular involvement, and number of fragments) were assessed. Outcome parameters were return to work, return to sports, VAS-FA, and SF-12. The influence of the fracture (1) location and (2) -characteristics on these parameters was tested. RESULTS: Thirty-nine patients (40 ± 15 years, 56% female) were enrolled with a mean follow-up of 22 ± 10 months. L&B type I fractures occurred in 59%, type II in 41%. Thirty-one percent of all fractures were dislocated, 74% intra-articular, and 41% multi-fragmentary. Patients returned to work after 17 ± 12 days, to sports after 53 ± 22 days. The VAS-FA score at the final follow-up was 96 ± 4, SF-12 PCS score 57 ± 5 and MCS score 51 ± 8. No complications were reported, no patient required surgery. None of the assessed outcome parameters differed significantly between (1) the different fracture locations (L&B type I vs. II) or (2) the different fracture characteristics (displacement, intra-articular involvement, and number of fragments). CONCLUSIONS: (1) Both, L&B I and II fractures featured excellent results with immediate full weightbearing. Consequently, L&B type I and II fractures should be summarized as epi-metaphyseal fractures. (2) Fracture displacement, articular involvement, and number of fragments did not influence the outcome. Therefore, functional treatment should be recommended for all epi-metaphyseal fractures.

Mesenchymal stem cells from osteoporotic patients reveal reduced migration and invasion upon stimulation with BMP-2 or BMP-7.

Fractures to the osteoporotic bone feature a delay in callus formation and reduced enchondral ossification. Human mesenchymal stem cells (hMSC), the cellular source of fracture healing, are recruited to the fracture site by cytokines, such as BMP-2 and BMP-7. Aim of the study was to scrutinize hMSC for osteoporosis associated alterations in BMP mediated migration and invasion as well as in extracellular matrix (ECM) binding integrin expression. HMSC were isolated from 18 healthy or osteoporotic donors. Migration was assessed using a collagen IV coated micro-slide linear gradient chamber and time-lapse microscopy. Invasion was analyzed utilizing an ECM coated transmembrane invasion assay. Quantitative real-time RT PCR was performed for the ECM binding integrins α1, α2, α3, α4, α5, α11, αv and ß1. HMSC from osteoporotic patients showed a significant increase of migration upon BMP-2 or FCS stimulation, as well as a significant increase of invasion upon BMP-2, BMP-7 or FCS stimulation. Nevertheless, the migration and invasion capacity was significantly decreased compared to healthy controls. Out of all integrins analyzed, collagen binding integrin α2 was significantly downregulated in hMSC from osteoporotic patients. In conclusion, we here demonstrate for the first time osteoporosis associated alterations in BMP mediated hMSC recruitment. These findings may underlie the reduced healing of osteoporotic fractures. Nevertheless, the maintained migration and invasion response upon BMP stimulation illustrates the therapeutic potential of these clinically approved substances in the treatment of osteoporotic fractures. Another therapeutic target may be the downregulation of the collagen binding integrin α2 in hMSC from osteoporotic patients.

Patient-Reported Outcomes following Tibial Plateau Fractures: Mid- to Short-Term Implications for Knee Function and Activity Level.

Background: Patients with complex proximal tibial plateau fractures (TPFs) tend to overestimate the prognosis of their injury, potentially due to factors such as a limited understanding, optimism, and the influence of the pain intensity. Understanding the reasons behind this misperception is crucial for healthcare providers to effectively communicate with patients and establish realistic expectations for treatment outcomes. The purpose of this study was to analyze the outcomes of TPFs, with a particular focus on patient-reported outcome measures concerning functional recovery, pain levels, and overall satisfaction with treatment. The authors aim to provide valuable insights into the realistic expectations and potential limitations that patients may encounter during their recovery journey. Methods: In this retrospective single-center study, all surgically treated TPFs between January 2014 and December 2019 with a minimum follow-up of 12 months were included. Several patient-reported outcome measures were obtained, including the International Knee documentation Committee Score (IKDC), Lyholm score, Tegner score, and visual analog scale (VAS) for pain. Fractures were classified according to Schatzker, and then subgrouped into simple (Schatzker I-III) and complex (Schatzker IV-VI) fractures. Results: A total of 54 patients (mean age 51.1 ± 11.9 years, 59.3% female) with a mean follow-up time of 3.9 years were included. Schatzker II fractures were present in 48% (n = 26) of the cases, with Schatzker III in 6% (n = 3), Schatzker IV fractures in 6% (n = 3), and Schatker VI fractures in 41% (n = 22) of the cases. All outcome scores showed a significant improvement between the first year after surgery and the last follow-up (mean: 3.9 years). Simple fractures showed significantly lower patient-reported outcomes when compared to the preinjury state; however, good to excellent results were observed. Patient-reported outcomes of complex fractures showed no significant changes in the study period with good to excellent results. When it comes to the Lysholm score, there were no significant differences in the outcome between simple and complex fractures. Furthermore, there was a return-to-sports rate of 100%, with high rates of changing sporting activity in 25% (simple fractures) and 45% in complex fractures. Conclusions: The data from this study showed that both simple and complex tibial plateau fractures show favorable outcomes at the midterm follow-up, and that injury severity does not correlate with worse results. While patients may tend to overestimate the recovery speed, this research highlights the importance of long-term follow-up, demonstrating a substantial improvement between one year post-surgery and the final evaluation. Return-to-sports rates were high, with adjustments needed for certain activities. However, patients should recognize the need to shift to lower-impact sports and the lengthy recovery process.

Overexpression of dnIKK in mesenchymal stem cells leads to increased migration and decreased invasion upon TNFα stimulation.

IκB kinase 2 (IKK-2) mediates tumor necrosis-factor α (TNFα) induced invasion of human mesenchymal stem cell (hMSC) to sites of tissue injury. Suppressing IKK-2 activity leads to reduced expression of proteolytic enzymes and impaired invasive capacity. In order to further reveal mechanisms of hMSC recruitment, we here aimed to analyse the impact of IKK-2 on two-dimensional migration upon TNFα stimulation in contrast to three-dimensional invasion. An immortalized hMSC line (SCP-1) was transduced with a dominant-negative mutant of IκB kinase 2 (SCP-1 dnIKK). Migration was assessed using a linear-gradient chemotaxis chambers by time-lapse analysis. Invasive capacity through human extracellular matrix was analysed using transwell invasion assays. RT-PCR confirmed increased IKK-2 expression levels in SCP-1 dnIKK cells, while TNFα receptor I and II expression was not altered. Invasion upon TNFα stimulation was significantly reduced by 78% in SCP-1 dnIKK. In contrast, migration was significantly increased, represented by a 60% elevated forward migration index and a 2.1-fold higher mean dislocation of the center of mass towards TNFα. In conclusion, our data confirms the impact of IKK-2 in TNFα dependent hMSC recruitment. Interestingly, reducing IKK-2 function increases two-dimensional migration towards TNFα, while invasive capacity is impaired. These findings contribute to a deeper understanding of MSC's biological properties orchestrating the complex processes of stem cell recruitment and homing.

Mesenchymal stem cells from osteoporotic patients feature impaired signal transduction but sustained osteoinduction in response to BMP-2 stimulation.

Osteoporotic fractures show reduced callus formation and delayed bone healing. Cellular sources of fracture healing are mesenchymal stem cells (MSC) that differentiate into osteoblasts by stimulation with osteoinductive cytokines, such as BMP-2. We hypothesized that impaired signal transduction and reduced osteogenic differentiation capacity in response to BMP-2 may underlie the delayed fracture healing. Therefore, MSC were isolated from femoral heads of healthy and osteoporotic patients. Grouping was carried out by bone mineral densitometry in an age-matched manner. MSC were stimulated with BMP-2. Signal transduction was assessed by western blotting of pSMAD1/5/8 and pERK1/2 as well as by quantitative RT-PCR of Runx-2, Dlx5, and Osteocalcin. Osteogenic differentiation was assessed by quantifying Alizarin Red staining. Osteoporotic MSC featured an accurate phosphorylation pattern of SMAD1/5/8 but a significantly reduced activation of ERK1/2 by BMP-2 stimulation. Furthermore, osteoporotic MSC showed significantly reduced basal expression levels of Runx-2 and Dlx5. However, Runx-2, Dlx5, and Osteocalcin expression showed adequate up-regulation due to BMP-2 stimulation. The global osteogenic differentiation in standard osteogenic differentiation media was reduced in osteoporotic MSC. Nevertheless, osteoporotic MSC were shown to feature an adequate induction of osteogenic differentiation due to BMP-2 stimulation. Taken together, we here demonstrate osteoporosis associated alterations in BMP-2 signaling but sustained specific osteogenic differentiation capacity in response to BMP-2. Therefore, BMP-2 may represent a promising therapeutic agent for the treatment of fractures in osteoporotic patients.

[Influence of the COVID-19 pandemic on fracture epidemiology exemplified by tibial plateau fractures]. / Einfluss der COVID-19-Pandemie auf die Frakturepidemiologie am Beispiel der Tibiaplateaufraktur.

BACKGROUND: During the COVID-19 pandemic interventions, such as contact restrictions, lockdowns and postponement of elective surgeries were taken to ease the burden on the healthcare system. Among the population, these interventions led to changes in recreational behavior as well as personal transportation. OBJECTIVE: This paper examines the epidemiological data of tibial plateau fractures (TPF) before and during the pandemic and to what extent pandemic control measures had an impact. MATERIAL AND METHODS: In this retrospective monocentric study of a German level 1 trauma center, the intra-articular tibial plateau fractures of the years 2019 and 2020 were compared regarding incidence, demographics, cause of the accident, and treatment strategy. Fracture classification was according to Schatzker, AO/OTA, and Moore. RESULTS: Incidence showed a decrease of -8.5% as well as a shift in the age incidence curves. There was a decrease in incidence during lockdown periods but also an increase in late summer 2020 compared to 2019. Tripping accidents (+12.4%) and bicycle accidents (+6.6%) increased in the pandemic year, whereas motorized traffic accidents (-7%) and skiing accidents (-10%) decreased. In terms of fracture morphology, 2020 showed an increase in impression fractures and a decrease in complex fractures. The number of surgically treated patients decreased by 7.3%. CONCLUSION: The 12 months of pandemic resulted in only a slight incidence decrease of intra-articular tibial plateau fractures. The pandemic control measures showed effects within the calendar year and led directly and indirectly to a change in incidence, cause of the accident, fracture entities and care strategy.

Changing patterns in the epidemiology of tibial plateau fractures: a 10-year review at a level-I trauma center.

PURPOSE: Mobility patterns of western societies have been changing due to ongoing demographic change. Therefore, continuously updated epidemiological data on fracture morphology and treatment strategies are needed. METHODS: This retrospective single-center study included all tibial plateau fractures (TPF) between January 2011 and December 2020 in a level-I trauma center in Central Europe. Epidemiology, trauma mechanism and fracture morphology were analyzed. Age- and sex-specific differences regarding fracture classification (Schatzker, AO/OTA, Moore) and changes during the study period are highlighted. RESULTS: A total of 607 patients (55.2% women, 44.8% men, mean age 52.9 years (± 17.9)) were included in the study, 462 (76.1%) thereof having undergone surgical treatment. Over the decade, an increase in mean age (+ 7.4 years; p = 0.10), incidence (+ 68%; p < 0.05) and low-energy trauma was observed, with the highest peak in elderly women. Within classifications, AO/OTA 41-B3 (24.9%), Schatzker II (26.8%) and Moore V (46.6%) fractures were the most common. CONCLUSION: Incidence (+ 68%), mean age and fractures with signs of knee dislocation of tibial plateau fracture increased over the last decade and low-energy trauma mechanism are more frequent. As the increase in incidence is mainly seen in older women, the comorbidities and need for immediate postoperative full weight-bearing have to be considered in treatment strategies.

Increased stemness and migration of human mesenchymal stem cells in hypoxia is associated with altered integrin expression.

Human mesenchymal stem cells (hMSCs) are regularly cultured and characterised under normoxic (21% O(2)) conditions, although the physiological oxygen tension in the stem cell niche is known to be as low as 1-2%. Oxygen itself is an important signalling molecule, but the distinct impact on various stem cell characteristics is still unclear. Therefore, the aim of this study was to evaluate the influence of oxygen concentration on the hMSC subpopulation composition, cell morphology and migration on different surfaces (polystyrene, collagen I, fibronectin, laminin) as well as on the expression of integrin receptors. Bone marrow-derived hMSCs were cultured either in normoxic (21% O(2)) or hypoxic (2% O(2)) conditions. The hMSC subpopulations were assessed by aspect ratio and cell area. Hypoxia promoted a more homogeneous cell population with a significantly higher fraction of rapidly self-renewing cells which are believed to be the true stem cells. Under hypoxic conditions hMSC volume and height were significantly decreased on all surfaces as measured by white light confocal microscopy. Furthermore, low oxygen tension led to a significant increase in cell velocity and Euclidian distance on all matrixes, which was evaluated by time-lapse microscopy. With regard to cell-matrix contacts, expression of several integrin subunits was evaluated by semi-quantitative RT-PCR. Increased expression of the subunits α(1), α(3), α(5,) α(6), α(11), α(v), ß(1) and ß(3) was observed in hypoxic conditions, while α(2) was higher expressed in normoxic cultured hMSCs. Taken together, our results indicate that hypoxic conditions promote stemness and migration of hMSC along with altering their integrin expression.

Reliability of 3D planning and simulations of medial open wedge high tibial osteotomies.

Purpose: In medial open-wedge high tibial osteotomy (HTO) hinge axis and osteotomy plane influence the resulting anatomy, but accurate angular quantifications using 3D-planning-simulations are lacking. The objectives of this study were developing a standardized and validated 3D-planning method of an HTO and to perform several simulated realignments to explain unintended anatomy changes. Methods: The cutting direction of the main osteotomy was defined parallel to the medial tibial slope and the hinge axis 1.5 cm distal to the lateral plateau. For interobserver testing, this 3D planning was performed on 13 digital models of human tibiae by two observers. In addition, four different hinge axis positions and five differently inclined osteotomy planes each were simulated. The osteotomy direction ranged from medial 0°-30° anteromedial, while the tilt of the osteotomy plane compared to the tibial plateau was -10° to +10°. All anatomic angular changes were calculated using 3D analysis. Results: Multiple HTO plannings by two medical investigators using standardized procedures showed only minimal differences. In the 3D-simulation, each 10° rotation of the hinge axis resulted in a 1.7° significant increase in slope. Tilting the osteotomy plane by 10° resulted in significant torsional changes of 2°, in addition to minor but significant changes in the medial proximal tibial angle (MPTA). Conclusion: Standardized 3D-planning of the HTO can be performed with high reliability using two-observer planning. 3D-simulations suggest that control of the osteotomy plane is highly relevant to avoid unintended changes in the resulting anatomy, but this can be a helpful tool to modify specific angles in different pathologies in the HTO.

Intraoperative alignment correlates well with long standing radiographs - The X-ray grid method in complex knee surgery.

OBJECTIVE: While long standing radiographs (LSR) represent the gold standard for preoperative alignment assessment and planning of lower limb deformity corrections, there is no consensus about the intraoperative alignment assesments (IAC) due to various limitations of the common methods. The present study introduces a radiolucent X-ray grid with integrated radiopaque lines explicitly designed for fluoroscopic IAC and evaluates its reliability in comparsion to the LSR. METHODS: Patients with posttaumatic and congenital lower limb deformity surgery and preoperative LSR as well as fluoroscopic IAC utilizing the X-ray grid were retrospectively included to the study. The mechanical axis deviation (MAD) in percentage of the maximum tibial width from the medial to the lateral in comparison between the image pairs was set as primary outcome parameter. Multiple rater and measurements determined intra- and interobserver reliabilit of both imaging methods. In addition, the effects of age, gender, body mass index (BMI), etiology, joint line convergence angle (JLCA), and extent varus or valgus deformity were analysed. RESULTS: A total of 84 patients were finally included. The mean absolute difference of MAD between the two techniques was 7.2 ± 0.8%. MAD between the LSR and IAC correlated at a high level (R = 0.96, p <0.001). The agreement decreased with increasing extent of deformity (p <0.01) and with higher deviation of JLCA between LSR and IAC (p <0.01). Intra- and interobserver concordance correlation coefficient (CCC) for MAD measurements were 0.99 for both imaging techniques. CONCLUSION: Fluoroscopy combined with the X-ray grid method is a valid tool for intraoperative assessment of lower limb alignment in deformity correction surgery, and the correlation between LSR and IAC is better than in other similar techniques described in the literature. However, in case of severe coronal alignment deformity and highly divergent JLCA, the agreement between both imaging techniques decreases significantly.

3D osteotomies-improved accuracy with patient-specific instruments (PSI).

PURPOSE: Three-dimensional (3D) printed patient-specific instruments (PSI) have been introduced to increase precision and simplify surgical procedures. Initial results in femoral and tibial osteotomies are promising, but validation studies on 3D planning, manufacturing of patient-specific cutting blocks and 3D evaluation of the attained results are lacking. METHODS: In this study, patient-specific cutting blocks and spacers were designed, fabricated, and used to perform a high tibial osteotomy (HTO). After segmentation of CT data sets from 13 human tibiae, 3D digital planning of the HTO was performed with a medial opening of 8 mm. These 3D models were used to fabricate patient-specific cutting blocks and spacers. After the surgical procedure, accuracy was evaluated measuring 3D joint angles and surface deviations. RESULTS: The lowest mean deviation was found to be 0.57° (SD ± 0.27) for the MPTA. Medial and lateral tibial slope deviated from the 3D planning by an average of 0.98° (SD ± 0.53) and 1.26° (SD ± 0.79), respectively, while tibial torsion deviated by an average of 5.74° (SD ± 3.24). Color analysis of surface deviations showed excellent and good agreement in 7 tibiae. CONCLUSION: With 3D cutting blocks and spacers, the 3D planning of the HTO can be translated into reality with small deviations of the resulting joint angles. Within this study, the results of the individual steps are examined for errors and thus a critical evaluation of this new and promising method for performing patient-specific HTOs is presented.

Bupivacaine, ropivacaine, and morphine: comparison of toxicity on human hamstring-derived stem/progenitor cells.

PURPOSE: Bupivacaine, ropivacaine, and morphine are commonly administered intraarticularly after anterior cruciate ligament (ACL) reconstruction. However, their effects on human tendon stem/progenitor cells (TSPC) have not been studied. Therefore, this study investigates the cytotoxicity of these analgetics on TSPC. METHODS: Cells were isolated from human hamstring grafts of 3 female (age 15, 16 and 59) and 2 male patients (age 16 and 47). Cells were incubated using 0.5% bupivacaine, 0.5/0.75% ropivacaine, and 0.025% morphine. Cell viability was assessed after 0.5, 2, and 6 h using live/dead assay. Metabolic activity and apoptosis were measured by WST- and Annexin-V-FACS-assay after 2 h. RESULTS: Cell viability remained unchanged after 0.5 h in all groups, while treatment with bupivacaine and 0.5/0.75% ropivacaine resulted in a complete cell loss after 6 h. Contrarily, morphine showed no cytotoxic effect. Cell viability and metabolism were significantly reduced after treatment with bupivacaine (22.1; 8.3%) and 0.75% ropivacaine (56.5; 23.8%), while 0.5% ropivacaine and morphine showed no significant difference compared with controls. Apoptosis was significantly induced after incubation with bupivacaine (58.1%) and 0.75% ropivacaine (26.2%), whereas 0.5% ropivacaine only led to a slight induction compared with morphine and controls. CONCLUSIONS: Clinically administered concentrations of bupivacaine (0.5%) and ropivacaine (0.75%) have a significant cytotoxic effect on human TSPC in vitro, while ropivacaine in a concentration of 0.5% has a mild but not significant effect on apoptosis and cell metabolism. In contrast, morphine does not affect cell survival, metabolism, or apoptosis. Knowing that morphine provides comparable to even prolonged pain reduction after ACL reconstruction, the presented in vitro study suggests morphine as a potentially less toxic analgetic drug for intraarticular application in clinical practice.

Morphological and immunocytochemical characteristics indicate the yield of early progenitors and represent a quality control for human mesenchymal stem cell culturing.

Human mesenchymal stem cells (hMSC) are a heterogeneous cell population, which is reflected in varying morphological and biological properties. Three subpopulations with intrinsic characteristics can be distinguished: small rapidly self-renewing cells, spindle-shaped cells and large, flattened cells. Unfortunately, it has neither been possible to morphologically define these distinct cells consistently, nor to relate them to specific surface marker features. Here, the primary hMSC subpopulations of three donors are clearly defined by maximum cell diameter and area. Furthermore, these cells were stained for the putative hMSC surface markers CD105, CD90 as well as CD73, and evaluated by three-colour flow cytometry and simultaneous multicolour immunocytochemistry. Interestingly, cell cultures with a high rate of triple-positive hMSC featured a higher content of rapidly self-renewing cells. On the other hand, a higher fraction of flattened cells correlated with a loss of one or more hMSC surface markers. The expression of CD73 showed the highest heterogeneity. Immunocytochemistry further confirmed that flattened cells mainly lack CD73 expression, whereas rapidly self-renewing cells were steadily positive for all three hMSC markers. In the literature, hMSC properties are especially conceded to rapidly self-renewing cells, whereas flattened cells have been suggested to represent early stages of lineage-specific progenitors. We reveal that among the recently suggested surface markers, CD73 is the most sensitive, as it seems to be down-regulated in the early stages of differentiation. Our morphological and immunocytochemical characterization of hMSC subpopulations indicates the yield of early multipotent hMSC and thereby provides a quality control approach for hMSC culturing.

IKK-2 is required for TNF-alpha-induced invasion and proliferation of human mesenchymal stem cells.

Mesenchymal stem cells (MSCs) can contribute to tissue repair by actively migrating to sites of tissue injury. However, the cellular and molecular mechanisms of MSC recruitment are largely unknown. The nuclear factor (NF)-kappaB pathway plays a pivotal role in regulating genes that influence cell migration, cell differentiation, inflammation, and proliferation. One of the major cytokines released at sites of injury is tumor necrosis factor-alpha (TNF-alpha), which is known to be a key regulator of the NF-kappaB pathway. Therefore, we hypothesized that TNF-alpha may lead to MSC invasion and proliferation by activation of the NF-kappaB pathway. TNF-receptor 1 and 2, NF-kappaB (p65), and IkappaB kinase 2 (IKK-2) are expressed in human MSCs (hMSCs). Stimulation of hMSCs with TNF-alpha caused a p65 translocation from the cytoplasm to nucleoplasm but did not change the expression profile of MSC markers. TNF-alpha strongly augmented the migration of hMSCs through the human extracellular matrix. Using lentiviral gene transfer, overexpressing a dominant-negative mutant of IKK-2 (dn-IKK-2) significantly blocked this effect. NF-kappaB target genes associated with migration (vascular cell adhesion molecule-1, CD44, and matrix metalloproteinase 9) were upregulated by TNF-alpha stimulation and blocked by dn-IKK-2. Moreover, using the bromodeoxyuridine assay, we showed that the inhibition of the NF-kappaB pathway caused a significant reduction in the basal proliferation rate. TNF-alpha stimulated the proliferation of hMSCs, whereas overexpression of dn-IKK-2 significantly blocked this effect. TNF-alpha led to the upregulated expression of the proliferation-associated gene cyclin D1. In conclusion, we demonstrated that the NF-kappaB pathway components, p65 and IKK-2, are expressed in hMSCs. Our data provide evidence that this signal transduction pathway is implicated in TNF-alpha-mediated invasion and proliferation of hMSCs. Therefore, hMSC recruitment to sites of tissue injury may, at least in part, be regulated by the NF-kappaB signal transduction pathway.

Proliferative and osteogenic differentiation capacity of mesenchymal stromal cells: Influence of harvesting site and donor age.

Human mesenchymal stromal cells (hMSCs) are the cellular source of new bone formation and an essential component of autologous bone grafts. Autologous bone graft harvesting is routinely conducted at the iliac crest, although alternative donor sites with lower complication rates are available. Thus, the aim of this study was to compare hMSCs harvested from the iliac crest and the proximal tibia regarding their proliferative and osteogenic differentiation capacity. Furthermore, we investigated the influence of donor age on these biological properties. HMSCs were isolated from iliac crest or proximal tibia bone grafts of 46 patients. Proliferative capacity was assessed by cumulative population doublings, population doubling time, colony forming units and cell proliferation assays. Osteogenic capacity was assessed by quantification of extracellular calcium deposition and marker gene expression levels. The number of hMSCs per gram harvested tissue was determined. Furthermore, the adipogenic and chondrogenic differentiation capacity were quantified using BODIPY and Safranin Orange staining, respectively. Additional analyses were carried out after grouping young (18-49 years) and aged (≥50 years) donors. HMSCs derived from the proximal tibia featured a comparable proliferative and osteogenic differentiation capacity. No significant differences were found for any analysis conducted, when compared to hMSCs obtained from the iliac crest. Furthermore, no significant differences could be revealed when comparing young and aged donors. This was equally true for hMSCs from both donor sites after comparison within the same age group. Our study demonstrates comparable biological properties of hMSCs derived from both donor sites, the iliac crest and the proximal tibia. Furthermore, aging does not alter proliferative and osteogenic differentiation capacity. Consequently, the proximal tibia should be considered more closely as an alternative donor site in patients of all age groups.