[Reconstruction of a metadiaphyseal bone defect after open comminuted fracture of the proximal femur using a modified Masquelet technique]. / Rekonstruktion eines metadiaphysären Knochendefekts nach offener, mehrfragmentärer Fraktur des proximalen Femurs in modifizierter Masquelet-Technik.

The reconstruction of segmental bone defects after surgical treatment of infected delayed unions as well as nonunions, places the highest demands on the surgical technical implementation. After treating the fracture-related infection, guaranteeing biomechanical stability is crucial for the success of the treatment. The presented case describes the successful treatment of an infected delayed union after an open metadiaphyseal comminuted fracture of the proximal femur using a modified Masquelet technique. A solid allogeneic bone graft in combination with autologous cancellous bone were inserted into a 7 cm subtrochanteric defect zone and stabilized with a combined plate and nail osteosynthesis.

Open versus minimally invasive fixation of thoracic and lumbar spine fractures in patients with ankylosing spinal diseases.

PURPOSE: Posterior multilevel fixation of traumatic instability in ankylosing spinal disease (ASD) can be performed by open surgery (OS) or minimally invasive surgery (MIS). We investigated whether both methods differ based on the reduction results and perioperative parameters. METHODS: In this retrospective cohort study, OS and MIS groups were investigated. The bisegmental Cobb angles and dislocation angles were measured using pre- and postoperative CT images, and the initial malalignment and achieved reduction were calculated. Cut-seam time, calculated blood loss, transfusion number, fluoroscopy time, pedicle screw placement accuracy, duration of ICU stay, in-patient stay, and complications (bleeding, postoperative thrombosis and embolism, and postoperative mortality) were recorded. RESULTS: Seventy-five ASD patients with spine fractures (Ø 75 ± 11 years, male: 52, female: 23) (MIS: 48; OS: 27) were included in this study. The extent of reduction did not differ in the OS and MIS groups (p = 0.465; MIS:- 1 ± 3°, OS:-2 ± 6°). The residual postoperative malalignment angle was not significantly different (p = 0.283). Seventy-eight of the implanted screws (11%) showed malpositioning. No difference was found between OS and MIS (MIS, 37 [7%]; OS, 41 [16%]; p = 0.095). MIS was associated with less blood loss (OS: 1.28 ± 0.78 l, MIS: 0.71 ± 0.57 l, p = 0.001), cut-seam time (MIS: 98 ± 44 min, OS: 166 ± 69 min, p < 0.001), and hospital stay (MIS: Ø14 ± 16 d, OS: Ø38 ± 49 d, p = 0.02) than OS. CONCLUSION: OS and MIS show equally limited performance in terms of the fracture reduction achieved. The MIS technique was superior to OS based on the perioperative outcome. Therefore, MIS should be preferred over OS for unstable spinal injuries, excluding C-type fractures, in ASD patients without neurological impairment.

[Closed reduction and minimally invasive fixation of a sacral avulsion fracture : Minimal invasiveness with maximum stability]. / Geschlossene Reposition und minimal-invasive Fixation einer sakralen Ausbruchfraktur : Minimale Invasivität bei maximaler Stabilität.

Surgical stabilization of high-energy sacral avulsion fractures with spinopelvic dissociation places high demands on the surgeon. The goal is to achieve maximum stability while minimizing invasiveness. The present case of a dislocated U­type fracture in a 25-year-old motocross rider exemplifies how a reduction with the targeted application of closed reduction techniques through hyperextension of the hip joints and lordosis in the lumbosacral hinge and through a standardized procedure in intraoperative fluoroscopic imaging, a minimally invasive stabilization by means of transsacral screw fixation and spinopelvic fixation of lumbar vertebra 5 to the ilium in the sense of a bilateral triangular stabilization is possible without compromising the achieved stability of the osteosynthesis. The limitations of the described approach are also pointed out.

[Surgical treatment strategy for traumatic luxation of the posterior tibial tendon : Case report and literature review]. / Operative Versorgungsstrategie einer traumatischen Luxation der Tibialis-posterior-Sehne : Fallbericht und Literaturvergleich.

Based on a case study, the injury pattern and surgical procedure for traumatic dislocation of the posterior tibial tendon is presented. A 32-year-old ice hockey player suffered a direct impact from a puck at the dorsomedial aspect of the inner ankle. In the course of the injury a ganglion developed due to recurrent dislocation of the posterior tibial tendon. Intraoperatively, a distracted retinaculum and a flattened retromalleolar sulcus were present. An open wedge osteotomy and suture anchor refixation of the retinaculum were performed. This procedure is described in the context of a review of the literature.

[Course of operative treatment of a sacral insufficiency fracture : Successful or serious treatment?] / Behandlungsverlauf der operativen Versorgung einer Sakruminsuffizienzfraktur : Erfolgreiches oder folgenreiches Handeln?

A monolateral sacrum fracture was primarily diagnosed with a CT and treated with PMMA augmented SI screw fixation. The following CT showed an unexpected contralateral fracture which led to the need for a lumbopelvic stabilization. In the course of 6 months, successively occurring adjacent fractures required recurrent vertebroplasty. Most of these fractures could only be diagnosed through MRI. It remains unclear, whether initially even the contralateral sacral ala was fractured.

[The complicated course of a femoral shaft fracture in childhood]. / Komplizierter Verlauf einer Femurschaftfraktur im Kindesalter.

We report a difficult healing process after a femoral shaft fracture in childhood. We present surgical correction options of femoral shortening due to pseudarthrosis after elastic stable intramedullary nailing. First, we tried to establish distraction using an external fixator, followed by plate osteosynthesis. After material failure of plate osteosynthesis, we treated the refracture with intramedullary nailing, after which bone healing occurred.

Calcium Microcrystal Formation in Recurrent Herniation Patients After Autologous Disc Cell Transplantation.

Autologous disc cell transplantation (ADCT) is a cell-based therapy aiming to initiate regeneration of intervertebral disc (IVD) tissue, but little is known about potential risks. This study aims to investigate the presence of structural phenomena accompanying the transformation process after ADCT treatment in IVD disease. Structural phenomena of ADCT-treated patients (Group 1, n = 10) with recurrent disc herniation were compared to conventionally-treated patients with recurrent herniation (Group 2, n = 10) and patients with a first-time herniation (Group 3, n = 10). For ethical reasons, a control group of ADCT patients who did not have a recurrent disc herniation was not possible. Tissue samples were obtained via micro-sequestrectomy after disc herniation and analyzed by micro-computed tomography, scanning electron microscopy, energy dispersive spectroscopy, and histology in terms of calcification zones, tissue structure, cell density, cell morphology, and elemental composition. The major differentiator between sample groups was calcium microcrystal formation in all ADCT samples, not found in any of the control group samples, which may indicate disc degradation. The incorporation of mineral particles provided clear contrast between the different materials and chemical analysis of a single particle indicated the presence of magnesium-containing calcium phosphate. As IVD calcification is a primary indicator of disc degeneration, further investigation of ADCT and detailed investigations assessing each patient's Pfirrmann degeneration grade following herniation is warranted. Structural phenomena unique to ADCT herniation prompt further investigation of the therapy's mechanisms and its effect on IVD tissue. However, the impossibility of a perfect control group limits the generalizable interpretation of the results.

[Impairment of oxygenation of patients in surgical intensive care : Early symptom of severe sepsis]. / Die Veränderung der Oxygenierung chirurgischer Intensivpatienten : Frühes Leitsymptom der schweren Sepsis.

BACKGROUND: Sepsis and septic shock are major contributors to morbidity and mortality in intensive care patients. Early identification and adequate therapy are of utmost importance to reduce the still high mortality in patients with severe sepsis. Many of the pathophysiologic changes are nonspecific. Thus, a combination of symptoms and laboratory results are necessary to confirm the diagnosis. Impairment of the Horovitz index is identified as being a primal prognostic criterion for early diagnosis in serious progression of sepsis, after exclusion of a few differential diagnoses. Based on this fact, the prevalence of this symptom compared to other sepsis parameters is of specific interest. METHOD: In a retrospective study 33 cases of serious sepsis were analysed during the patient's course of intensive care treatment focusing on oxygenation. The deterioration of oxygenation, meaning a drop in the Horovitz index below 200 mm Hg (25.7 kPa) or a decrease in paO2 by 67.5 mm Hg (9 kPa) in spontaneously breathing patients with sepsis was the mean inclusion criteria. We compared the sequence of occurrence of known sepsis markers (e. g. PCT, WBC, CRP) with the deterioration in oxygenation to answer the question whether impairment of oxygenation could be an early symptom of severe sepsis. The Mann Whitney U­test and a discriminant analysis were performed to verify differences of the variables investigated between surviving and deceased patients. Furthermore a regression analysis was performed to confirm the results of the discriminant analysis. RESULTS: The mean drop in the Horovitz index was 90 ± 24 mm Hg (12 ± 3.2 kPa) within 4.5 h respectively. This was highly significant (p < 0.001). In all patients impairment of oxygenation indicated an individual onset and further progression of a serious sepsis. In more than ¾ of all cases this symptom occurred in an earlier stage than other organ dysfunctions. In 79 % of cases, patients showed an impairment of oxygenation before PCT increased on values of >2 ng/ml. In 76 % of cases impairment of oxygenation occurred earlier than all other investigated parameters. Significant differences were found between surviving and deceased patients regarding to their age as well as the timeframe from the beginning of impaired oxygenation to the onset of the effect of the administered antibiotics. These two parameters (age, time to sufficient antibiotic therapy) were confirmed by regression analysis and showing similar effect coefficients, age 1.09 and time to sufficient antibiotic therapy 1.04 respectively. CONCLUSION: An urgent worsening of pulmonary function in patients in intensive care requires immediate differential diagnostics due to substantial therapeutic consequences. Our results confirm that impairment of pulmonary oxygenation is the first prognostic symptom of severe onset of sepsis. Consequently, we recommend that this parameter be considered in diagnostic staging. After exclusion of a few differential diagnoses impairment of oxygenation can be the very first symptom of severe sepsis. The patient's age and time to sufficient antibiotic therapy are two very important prognostic factors with respect to mortality. Early and sufficient antibiotic therapy, and in a few cases surgical intervention are of utmost importance.

[Elbow dislocation with ipsilateral proximal radial shaft fracture and radial head dislocation]. / Ellenbogenluxation mit ipsilateraler proximaler Radiusschaftfraktur und Radiusköpfchenluxation.

Elbow dislocation with ipsilateral proximal radial shaft fracture and dislocated radial head is a rarely described injury. In this article we present the case of a 23-year-old man with this injury. After the initial diagnostics, the radial shaft fracture was osteosynthetically fixed, whereby the anatomical positions of all parts of the elbow joint were correctly aligned and the medial collateral ligament was reconstructed. After 4.5 months the radial shaft fracture was healed with nearly complete functional recovery of the upper extremity. Thus, a good outcome can be expected when all aspects of bony and ligamentous injuries are accurately addressed.

Three-dimensional virtual simulation and evaluation of the femoroacetabular impingement based on "black bone" MRA.

INTRODUCTION: Femoroacetabular impingement (FAI) is a recognised cause of secondary osteoarthritis of the hip. Several imaging methods have been used to analyse the pathologic signs. Because of the lack of precise pre- and intraoperative overview and the difficulty locating osseous pathologies, arthroscopic and minimal invasive treatment is still challenging, even for trained surgeons. This paper describes a procedure that is based on magnetic resonance arthrography (MRA) and is used to virtually verify the range of motion (ROM) of the hip. It enables the evaluation of FAI and the preoperative simulation of adequate surgical manoeuvres. METHODS: Each MRI was completed on a 3.0 T system using a flexible transmit/receive surface body coil with the patient in the supine position. An axial three-dimensional (3D) gradient-echo (VIBE, volume interpolated breathhold examination) sequence was performed. For the generation of 3D bone models, semiautomatic segmentation of the MRA data was accomplished using Amira(®) visualisation software version 5.2. The self-developed software "HipProject", written in C++, computes the maximal ROM of the hip. The virtual colliding regions were visualised for verification and simulation of osseous trimming. RESULTS: In addition, for necessary information about damage to the cartilage and labrum, "black bone" MRA was used to generate extremely precise 3D reconstructions of the hip joint to automatically calculate the preoperative osseous ROM. Furthermore, the acetabular and femoral locations of the impingement zone were individually visualised and quantified. CONCLUSIONS: The described procedure is a useful tool for the preoperative investigation of impinging hips. It enables appropriate planning of required surgical interventions.

[Aggravated reduction of the posterior malleolar fracture due to incarceration of the flexor digitorum longus tendon]. / Repositionshindernis des hinteren Volkmann-Dreiecks durch Interposition der Sehne des M. flexor digitorum longus.

The indications for stabilization of the posterior malleolus (Volkmann triangle) while fixing ankle fractures are controversially discussed. Detailed descriptions of possible obstacles to reduction are scarce. The following case describes the difficulty of reduction of the posterior malleolus caused by interposition of the flexor digitorum longus tendon. The fracture line of the posterior malleolus passed in an atypical manner vertically to the posterior-medial tibial margin with direct contact to the anatomical pathway of the tendon. The impaction of the tendon was already present in the computed tomography (CT) scan taken preoperatively but the tendon hindering malleolar reduction was first realized during surgery after several unsuccessful attempts at repositioning.

Anatomical conditions of the posterior pelvic ring regarding bisegmental transverse sacroiliac screw fixation: a 3D morphometric study of 125 pelvic CT datasets.

INTRODUCTION: Sacroiliac (SI) screws are used for osteosynthesis in unstable posterior pelvic ring injuries. In the cases of "sacral dysplasia", in which the elevated upper sacrum does not allow a secure SI screw insertion into the S1 level, the S2 segment must be used to achieve stable fixation. The bone quality of the S2 segment is thinner compared to that of the S1 vertebra and may cause biomechanical weakness. An additional SI screw insertion into the S3 level may improve stability. With respect to the anatomical conditions of the posterior pelvic ring, there have been no anatomical investigations to date regarding SI screw placement into the third sacral segment. MATERIALS AND METHODS: CT raw datasets from 125 patients (ø59 years, ø172 cm, ø76 kg) were post-processed using Amira 5.2 software to generate 3D pelvic models. A program code implemented in C++ computed a transverse bone corridor for the first, second and third sacral segments for a typical SI screw diameter of 7.3 mm. Volume, sagittal cross-section, iliac entrance area and length of the determined screw corridors were measured. A confidence interval of 95 % was assumed (p < 0.05). RESULTS: The fully automatic computation revealed a possible transverse insertion for one 7.3-mm screw in the third sacral segment in 30 cases (24 %). The rate (60 %) of feasible S3 screw placements in the cases of sacral dysplasia (n = 25) is significantly higher compared to that (15 %) of "normal" sacra (n = 100). With regard to the existence of transverse iliosacroiliac corridors as a function of sacral position in between the adjacent iliac bone bilaterally, a new classification of three different shape conditions can be made: caudad, intermediate minor, intermediate major, and cephalad sacrum. Gender, age, body height and body weight had no statistically significant influence on either possible screw insertion or on the calculated data of the corridors (p > 0.05). CONCLUSION: SI screw insertion into the third sacral level deserves discussion in the cases of sacral dysplasia. Biomechanical and practical utility must be verified.

Comparison of palmar fixed-angle plate fixation with K-wire fixation of distal radius fractures (AO A2, A3, C1) in elderly patients.

The objective of this prospective, randomized, controlled trial was to compare the results of two operative techniques used for the treatment of unstable distal radius fractures in elderly patients classified as AO types A2, A3, and C1. Patients were treated with either fixed-angle volar plates or K-wires using a combined Kapandji and Willenegger technique. The functional results were determined after 3, 6, and 12 months. We included 40 patients aged over 65 years. Twenty-one patients were treated with plate fixation and 19 with K-wire fixation. The functional results, after 1 year, were nearly the same in both treatment groups, suggesting that either method is suitable for the treatment of unstable distal radius fractures of AO types A2, A3, and C1 in elderly patients. Sixteen of 21 patients with plate fixation and 17 of 19 patients with K-wire fixation present good results as assessed by the Castaing score. The median DASH score was three in both groups after 1 year. The patients with plate fixation were able to resume activities of daily living 4 weeks earlier. The most common complication was an intermediate post-traumatic median nerve irritation. Both methods are suitable for the treatment of elderly patients with unstable distal radius fractures of AO types A2, A3, and C1. If early functional post-operative care is important, palmar fixed-angle plate fixation is an ideal treatment approach. Otherwise, K-wire fixation is an effective, minimally invasive method with comparable clinical results.

The development of cerebral amyloid angiopathy in cerebral vessels. A review with illustrations based upon own investigated post mortem cases.

The process of ß-amyloid accumulation in cerebral vessels is presented. Cerebral amyloid angiopathy (CAA) was confirmed during an autopsy. It was diagnosed according to the Boston criteria. Cerebral amyloid angiopathy can involve all kinds of cerebral vessels (cortical and leptomeningeal arterioles, capillaries and veins). The development of CAA is a progressive process. ß-amyloid appears first in the tunica media, surrounding smooth muscle cells, and in the adventitia. ß-amyloid is progressively accumulated, causing a gradual loss of smooth muscle cells in the vessel wall and finally replacing them. Then, the detachment and delamination of the outer part of the tunica media results in the "double barrel" appearance, fibrinoid necrosis, and microaneurysm formation. Microbleeding with perivascular deposition of erythrocytes and blood breakdown products can also occur. ß-amyloid can also be deposited in the surrounding of the affected vessels of the brain parenchyma, known as "dysphoric CAA". Ultrastructurally, when deposits of amyloid fibers were localized in or outside the arteriolar wall, the degenerating vascular smooth muscle cells were observed. In the Institute of Psychiatry and Neurology the study was carried out in a group of 48 patients who died due to intracerebral hemorrhage caused by sporadic CAA.

The influence of sacral morphology on the existence of secure S1 and S2 transverse bone corridors for iliosacroiliac screw fixation.

Sacroiliac (SI) screw fixation for unstable pelvic fractures stands out as the only minimally invasive method among all other ORIF procedures. A strictly transverse screw trajectory is needed for central or bilateral fracture patterns up to a complete iliosacroiliac fixation. However, secure screw insertion is aggravated by a narrow sacroiliac bone stock. This study investigates the influence of a highly variable sacral morphology to the existence of S1 and S2 transverse corridors. The analysis contained in this study is based on 125 CT datasets of intact human pelvises. First, sacral dysplasia was identified using the "lateral sacral triangle" method in a lateral 3-D semi-transparent pelvic view. Second, 3-D corridors for a 7.3mm screw in the upper two sacral levels were visualised using a proprietary IT workflow of custom-made programme scripts based on the Amira(®)-software. Shape-describing measurement variables were calculated as output variables. The results show a significant linear correlation between ratioT and the screw-limiting S1 isthmus height (Pearson coefficient of 0.84). A boundary ratio of 1.5 represented a positive predictive value of 96% for the existence of a transverse S1-corridor for at least one 7.3mm screw. In 100 out of 125 pelvises (80%), a sufficient S1 corridor existed, whereas in 124 specimens (99%), an S2 corridor was found. Statistics revealed significantly larger S1 and S2 corridors in males compared to females (p<0.05). However, no gender-related differences were observed for clinically relevant numbers of up to 3 screws in S1 and 1 screw in S2. The expanse of the S1 corridor is highly influenced by the dimensions of the dysplastic elevated upper sacrum, whereas the S2 corridor is not affected. Hence, in dysplastic pelvises, sacroiliac screw insertion should be recommended into the 2nd sacral segment. Our IT workflow for the automatic computation of 3-D corridors may assist in surgical pre-operative planning. Furthermore, the workflow could be implemented in computer-assisted surgery applications involving pelvic trauma.

Potentialities and limitations of a database constructing three-dimensional virtual bone models.

BACKGROUND: 3D bone reconstructions performed during general clinical practice are of limited use for preclinical research, education, and training purposes. For this reason, we are constructing a database of human 3D virtual bone models compiled from computer tomography (CT) scans. MATERIALS AND METHODS: CT data sets were post-processed using Amira(®) 5.2 software. In each cut, bone structures were isolated using semiautomatic labeling program codes. The software then generated extremely precise 3D bone models in STL format (standard triangulated language). These bone models offer a sustainable source of information for morphologic studies and investigations of biomechanical bony characteristics in complex anatomic regions. Regarding educational value and student acceptance models were introduced during bedside teaching and evaluated by medical students. RESULTS: The current database is comprised of 131 pelvises and 120 femurs (ø 60 years, ø 172 cm, ø 76 kg), and is continuously growing. To date, 3D morphometric analyses of the posterior ring and the acetabulum have been successfully completed. Eighty students (96 %) evaluated instruction with virtual 3D bone models as "good" or "very good". The majority of students want to increase learning with virtual bone models covering various regions and diseases. CONCLUSION: With consistent and steadily increasing case numbers, the database offers a sustainable alternative to human cadaver work for practical investigations. In addition, it offers a platform for education and training.

The lateral sacral triangle--a decision support for secure transverse sacroiliac screw insertion.

Sacroiliac (SI) screw fixation represents an effective method to stabilise pelvic injuries. However, to date neither reliable radiological landmarks nor effective anatomical classifications of the sacrum exist. This study investigates the influence of variability in sacral shape on secure transverse SI-screw positioning. Furthermore, consistent correlations of these anatomical conditions are analysed with respect to standard planar pelvic views. For shape analysis, 80 human computed tomography data sets were segmented with the software Amira 4.2 to obtain 3D reconstructions. We identified anatomical conditions (ACs) according to the extent of the effect on the bony screw pathway. Subsequently, the pelvis was spatially aligned using representative bone protuberances in order to create standard Matta projections. In each view, the ACs were described in terms of distance from bone landmarks. Three-dimensional shape analysis revealed the height of the pedicular isthmus (PH) as the limiting variable for secure screw insertion. The lateral and outlet views allowed an orthogonal projection of PH. In the lateral view, the ratio of the lateral sacral triangle framed by the S1 body height and width showed a high correlation to PH (p = 0.0001). A boundary ratio of 1.5 represented a reliable variable to determine whether or not a screw can be inserted (positive predictive value: 97%). In the outlet view, the distance between the S1 endplate and the SI joint top level (EJ) strongly correlated with PH (p = 0.0001). With EJ 0 mm, screw insertion was possible in all cases (100%). SI-screw insertion requires a well-planned procedure. Orientation of the sacral pedicle is of extreme relevance. A narrow sacroiliac channel and high sacral shape variability limit secure screw placement. However, no determining parameters exist, allowing accurate prediction of secure screw insertion based on X-rays or fluoroscopy. The lateral sacral triangle in the lateral view represents a simple and accurate preoperative method of support for the surgeon's decision to undertake this procedure. No additional technical effort is necessary. A boundary ratio of 1.5 predicts a sufficient bone stock for at least one 7.3 mm screw. Furthermore, the evaluation of the outlet projection can be used to assess the safety of the operation. Basically, a preoperative lateral pelvic image should be mandatory.

[Acute compartment syndrome of the lower leg due to knee arthroscopy]. / Akutes Kompartmentsyndrom des Unterschenkels nach Kniegelenkarthroskopie.

This case report describes an acute postoperative compartment syndrome of the lower leg following simple arthroscopy of the knee. The diagnostics as well as the time course of further therapeutic procedures are considered critically. Furthermore, the surgical workflow is analyzed for possible reasons. Retrospectively, an accumulation of irrigation fluid passing through a popliteal cyst into the superficial flexor compartment must be suspected. In summary, even with an optimal perioperative management the subsequent compartment syndrome due to knee arthroscopy cannot be avoided with any certainty. However, immediate causal therapy lies in the urgent dermatofasciotomy to prevent irreversible neuromuscular damage.

[Results of single stage vs. two-stage total knee arthroplasty]. / Ergebnisse einzeitiger vs. zweizeitiger bilateraler Knietotalendoprothetik.

BACKGROUND: The total knee arthroplasty (TKA) is a successful procedure. In cases of bilateral knee osteoarthritis, advantages of single stage TKA vs. two-stage TKA as well as the gap between the procedures in case of two-stage TKA are discussed controversially. The aim of the present study is to compare the clinical and radiographic results of single stage bilateral TKA and two-stage bilateral TKA. In cases of two-stage TKA the dependency on the gap between surgeries was determined. MATERIAL AND METHODS: In this retrospective study 43 patients with single stage TKA and 35 patients after two-stage TKA with a maximum of 12 months between surgeries were included. Follow-up was in mean 31 ± 15 months. For clinical and radiological evaluation the Knee Society score (KSS) and Stolzalpen knee score were used. Quality of life was measured by the SF-36 score. The pain was determined using a visual analogue scale (VAS). Radiological evaluation was done by use of Knee Society roentgenographic evaluation and scoring system. RESULTS: The overall hospital stay for patients with two-stage TKA (26 ± 5 days) was twice as long as for patients with single stage TKA (14 ± 4 days). Patients with single stage bilateral TKA had a significantly higher KSS level (186 ± 19 points) than patients after two-stage bilateral TKA (179 ± 22 points). Within the two-stage group the best range of motion was achieved by patients with a gap of 4 to 6 months between surgeries and a decreased point value was measured in patients with a gap of 10 to 12 months between TKAs. Using the VAS patients with simultaneous bilateral TKA had significantly increased pain levels during passive motion. Within the two-stage group there were no differences in VAS. The results of Stolzalpen knee score were comparable in both groups. The analysis of radiological measurements showed a significantly higher number of radiolucent lines (1 mm) in patients with single stage TKA without any clinical relevance or progress in follow-up. Patients with single stage bilateral TKA had a higher complication rate than patients with a two-stage procedure. In the single stage group 6 patients had to be revised because of fracture, dislocation, peroneal nerve palsy, patella lateralisation or loosening. In the two-stage group only one patient had to be revised due to a quadriceps tendon rupture caused by a fall at day one after surgery. CONCLUSION: Analysis of clinical and radiological results shows only marginal differences between the two groups. In two-stage procedures functional results were best when the second surgery was done 4 to 6 months after the first procedure. Single stage TKA had a significantly higher complication rate. However, patient and surgeon should make the decision for single or two-stage bilateral TKA individually.

Cellular compatibility of highly degradable bioactive ceramics for coating of metal implants.

Resorbable ceramics can promote the bony integration of implants. Their rate of degradation should ideally be synchronized with bone regeneration. This study examined the effect of rapidly resorbable calcium phosphate ceramics 602020, GB14, 305020 on adherence, proliferation and morphology of human bone-derived cells (HBDC) in comparison to ß-TCP. The in vitro cytotoxicity was determined by the microculture tetrazolium (MTT) assay. HBDC were grown on the materials for 3, 7, 11, 15 and 19 days and counted. Cell morphology, cell attachment, cell spreading and the cytoskeletal organization of HBDC cultivated on the substrates were investigated using laser scanning microscopy and environmental scanning electron microscopy. All substrates supported sufficient cellular growth for 19 days and showed no cytotoxicity. On each material an identical cell colonisation of well communicating, polygonal, vital cells with strong focal contacts was verified. HBDC showed numerous well defined stress fibres which give proof of well spread and strongly anchored cells. Porous surfaces encouraged the attachment and spreading of HBDC. Further investigations regarding long term biomaterial/cell interactions in vitro and in vivo are required to confirm the utility of the new biomaterials.