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The Trans Iliacal Internal Fixator (TIFI) is a minimally invasive technique for the stabilization of sacro-iliac joint ruptures and fractures lateral to the sacral ala or through the sacral foramen. In this study, 7.0 mm pedicle screws of the Universal-Spine-System (USS, Synthes) were inserted 1-2 cm on the cranial side of the posterior superior iliac spine and parallel to the superior gluteal line. The connecting bar was inserted subfascially and fixed with the locking head pedicle screws to form an fixed-angle construction. In a prospective study 31 patients with vertical shear injuries of the pelvis were treated with the TIFI. There were two wound infections and one loosening of a pedicle screw. None of the screws were incorrectly positioned and no neuro-vascular lesions were caused by the implant. 2 years postoperatively we found 50% good and excellent results for type C pelvic ring injuries. Early findings show that the TIFI is well suited to stabilization of sacro-iliac joint ruptures and fractures of the lateral sacrum. Closed reduction and minimally invasive insertion technique are possible. The implant leads to sufficient biomechanical stability but there is a very low intraoperative risk of neuro-vascular lesion.

In the presented prospective study 35 consecutive patients with displaced 3- and 4-part fractures of the proximal humerus, including fracture dislocations, were treated with a fixator plate comprising angular stability between May 2001 and December 2002. After 18.5 (8-29) months 31 (89%) fractures were available for follow-up. Good and very good results were obtained in 64%. A poor result was documented in 23%. 64% of the patients had no or mild pain, 71% were able to abduct the arm over 90 degrees . Fracture classification according to Neer and AO had no influence on the outcome, with a mean Constant Score of 76 points. Partial avascular necrosis (AVN) of the humeral head was seen in 16% of all cases representing 4% of the fractures without dislocation and 80% of the fracture dislocations. Fracture dislocation (p=0.02) and AVN (p=0.005) had a negative effect on the Constant Score, with AVN being a predictor for a high level of pain (p=0.04). Secondary dislocation of the greater tuberosity was seen in two patients, loosening of screws in one patient and a fracture below the plate in another one. Secondary dislocation or loss of reduction of the head was not recorded. Angle stable plate fixation with tension band wiring of the tuberosities is an effective and safe option to treat this difficult fractures, also in elderly patients with osteoporotic bone. Because 40% of the 4-part fractures with fracture dislocation yielded a satisfactory or better result, the plate fixator with angular stability may be an alternative to prosthetic replacement in selected cases.

Closed reduction of the long bones is associated with the use of considerable force. This force must be maintained for the reduction maneuver and fixation process. At present, apart from the extension table or the large AO distractor, only rather inadequate reduction aids are available. A solution to this problem is being sought in the form of a robotic system with which precision can be improved and the holding effort reduced. In the research project presented here, a synthetic femur with integrated tensioned mainspring and a 32-A3 type fracture served as a bone reduction model. The fracture was stabilized with a standard AO fixator. A Stäubli robot (model RX130) was converted by appropriate modification so that it could be used for the reduction of femoral shaft fractures in vitro. The robot was equipped with a pneumatic 2-fingered gripper, on which the fingers have been modified so that they can grip the AO fixator clamp. A Force-Feedback-Sensor was inserted between the gripper and the robot to obtain online recordings of the forces and moments in all three axes. With this setup it is possible to achieve precise reduction of the fracture in all planes under visual control.

The effects of cyclic, mechanical compression on human bone marrow-derived mesenchymal progenitor cells undergoing chondrogenic differentiation were examined in this study. Mesenchymal progenitor cells were injected into cylindrical biodegradable scaffolds (hyaluronan-gelatin composites), cultured in a defined, serum-free chondrogenic medium and subjected to cyclic, mechanical compression. Scaffolds were loaded for 4 hours daily in the first 7 days of culture. At 1, 7, 14 and 21 days of culture, scaffolds were harvested for reverse transcriptase Polymerase Chain Reaction (RT-PCR), histology, quantitative DNA, proteoglycan and collagen analysis. Scaffolds loaded for 7 days showed a significant upregulation especially of chondrogenic markers (type II collagen, aggrecan; p<0.0001). No significant difference could be found for DNA content between loaded samples and unloaded controls. At day 1 in culture no significant differences in proteoglycan- and collagen contents could be detected between unloaded and loaded samples. After 21 days the proteoglycan (p<0.001) and collagen contents (p<0.0001) were significantly higher in the loaded samples compared to unloaded controls. By histological analysis (toluidine blue) a higher amount of proteoglycan-rich, extracellular matrix production throughout the matrix could be detected for loaded samples compared to unloaded controls. This study indicates that cyclic, mechanical compression enhances the expression of chondrogenic markers in mesenchymal progenitor cells differentiated in vitro resulting in an increased cartilaginous matrix formation, and suggests that mechanical forces may play an important role in cartilage repair.

Purpose: A prospective study to assess the value of indirect magnetic resonance-arthrography (MR-Arthro) in the detection of lesions of the superior labrum (SLAP-lesions)., Materials and Methods: Unenhanced magnetic resonance imaging (MRI) and indirect MR-Arthro of the shoulder were performed in 35 patients (9 females and 26 males) with a history of acute or chronic shoulder disorder. The images of unenhanced MRI and indirect MR-Arthro were analyzed independently from each other for the occurrence of SLAP-lesions and the findings correlated with the arthroscopic results. For arthroscopy, MRI and MR-Arthro, the SLAP-lesions were categorized based on the classification system of Snyder., Results: SLAP-lesions were diagnosed by arthroscopy in 22 of 35 patients (63 %). 9 of the 22 lesions (41 %) were classified as type 1, 9 (41 %) as type 2, three (13.5 %) as type 3 and one (4.5 %) as type 4. Using unenhanced MRI sensitivity, specificity and accuracy in the detection of SLAP-lesions were calculated to be 73 %, 85 % and 77 %. Indirect MR-Arthro showed a sensitivity of 91 %, a specificity of 85 % and an accuracy of 89 %. Unenhanced MRI revealed correlation to the arthroscopic classification in 9 of 22 cases (41 %) and indirect MR-Arthro in 18 of 22 cases (82 %)., Conclusion: Indirect MR-Arthro is a non-invasive method which offers excellent sensitivity in the diagnosis of SLAP-lesions. It provides important preoperative informations with regard to the exact location and extent of a tear.

Rationale and Objectives: The purpose of this study was to evaluate image quality and clinical acceptance of a large-area, flat-panel X-ray detector for routine skeleton examinations at 50% dose reduction., Methods: A total of 153 examinations (307 images) of 100 consecutive patients were evaluated. The cesium iodide-amorphous silicon active-matrix imager had a panel size of 43 x 43 cm, a matrix of 3000 x 3000, and a pixel pitch of 143 microm. All images were obtained with a kilovoltage setting identical to conventional radiographies of speed class 400. The amperage values were reduced by 50% compared with standard dose. Images were presented to 3 radiologists, who subjectively rated image quality on a 4-point scale according to 5 criteria (bone cortex, bone trabecula, soft tissue, overall contrast, and overall impression). Three trauma surgeons rated the clinical acceptance on a 4-point scale. Clinical acceptance was defined as directly derived consequences or therapy based on the presented image quality. For both evaluations, 1 represented excellent, 2 represented good, 3 represented moderate, and 4 represented nondiagnostic image quality/clinical acceptance. Intermediate scores at 0.5 intervals were allowed., Results: The mean values for all 5 image quality criteria were rated good or excellent (< or = 2). A total of 4.2% (13 of 307) of the images were rated 2.5 to 3.5 concerning the overall impression. None of the imaging features was ranked more than 3.5 by any radiologist. The mean value of the clinical acceptance was between good and excellent (1.47). A total of 98.7% (151 of 153) of the examinations were rated < or = 2.5; 1.3% (2 of 153) of examinations were of moderate clinical acceptance (< or = 3.5). None of the examinations was of nondiagnostic image quality or clinical acceptance (>3.5); therefore, no study had to be repeated., Conclusion: Routine skeleton images with 50% dose reduction yield good image quality and good clinical acceptance. In cases with abundant soft tissue, less dose reduction or standard dose is required.

Background: Measurement of the bending stiffness a healing fracture represents a valid variable in the assessment of fracture healing. However, currently available methods typically have high measurement errors, even for mild pin loosening. Furthermore, these methods cannot provide actual values of bending stiffness, which precludes comparisons among individual fractures. Thus, even today, little information is available with regards to the fracture healing pattern with respect to actual values of bending stiffness. Our goals were, therefore: to develop a measurement device that would allow accurate and sensitive measurement of bending stiffness, even in the presence of mild pin loosening; to describe the course of healing in individual fractures; and help to evaluate whether the individual pattern of bending stiffness can be predicted at an early stage of healing., Methods: A new measurement device has been developed to precisely measure the bending stiffness of the healing fracture by simulating four-point-bending. The system was calibrated on aluminum models and intact tibiae. The influence of pin loosening on measurement error was evaluated. The system was tested at weekly intervals in an animal experiment to determine the actual bending stiffness of the fracture. Transverse fractures were created in the right tibia of twelve sheep, and then stabilized with an external fixator. At ten weeks, bending stiffness of the tibiae were determined in a four-point-bending test device to validate the in-vivo-measurement data., Results: In-vivo bending stiffness can be measured accurately and sensitive, even in the early phase of callus healing. Up to a bending stiffness of 10 Nm/degree, measurement error was below 3.4% for one pin loose, and below 29.3% for four pins loose, respectively. Measurement of stiffness data over time revealed a significant logarithmic increase between the third and seventh weeks, whereby the logarithmic rate of change among sheep was similar, but started from different levels. Comparative measurements showed that early individual changes between the third and fourth weeks can be used as a predictor of bending stiffness at seven weeks (r = 0.928) and at ten weeks (r = 0.710)., Conclusion: Bending stiffness can be measured precisely, with less error in the case of pin loosening. Prediction of the future healing course of the individual fracture can be assessed by changes from the third to the fourth week, with differences in stiffness levels. Therefore, the initial status of the fracture seems to have a high impact on the individual healing course.

In eight patients with delayed union or nonunion after 3 degrees open fracture of the tibia, a minimally invasive technique of autologous bone grafting was performed. Bone harvesting from the iliac crest and debridement of the fracture side were done percutaneous by using a 5.5 mm acromionizer without complications. In seven of eight patients complete fracture healing could be achieved (88%). Percutaneous autologous bone grafting can be recommended on limited bone defects in patients with nonunion or delayed union of the tibia and severe soft tissue damage in the lower leg.