[Outcome after plate stabilization of symphyseal diastasis]. / Ergebnisse nach Plattenstabilisierung der Symphysensprengung.

BACKGROUND: Separation of the pubic symphysis with corresponding diastasis can be stabilized by symphyseal plating. OBJECTIVE: Which pelvic injuries are stabilized with symphyseal plating and what is their outcome? MATERIAL AND METHODS: A retrospective evaluation of 64 patients who underwent symphyseal plating over a period of 24 months was conducted. RESULTS: Of the patients 56 were male and 8 female with a mean age of 44 years (SD ± 17 years). The main cause of the pelvic injuries were traffic accidents. The distribution according to the AO fracture classification was 14â€¯× B1, 10â€¯× B2, 5â€¯× B3, 23â€¯× C1, 9â€¯× C2 and 3â€¯× C3 injuries. The distribution according to the Young and Burgess classification showed 9â€¯× APC I, 18â€¯× APC II, 13â€¯× APC III, 9â€¯× LC I, 3â€¯× LC II, 2â€¯× LC III and 10â€¯× VS injuries. The mean Injury Severity Score (ISS) was 32 (SD ± 17) and the mean inpatient stay was 29 days (SD ± 16 days; positive correlation p ≤ 0.001). Radiological implant loosening occurred in 52 patients. 14 patients required treatment for severe complications. The leading reason for revision surgery was implant failure (n = 8). CONCLUSION: These observations suggest that radiological signs of implant loosening are commonly observed but rarely the reason for revision surgery. Complete implant failures, however; occur mainly within the first postoperative weeks and require early revision. A timely clarification by additional X-ray imaging should be carried out if this is suspected.

Perioperative redistribution of regional ventilation and pulmonary function: a prospective observational study in two cohorts of patients at risk for postoperative pulmonary complications.

BACKGROUND: Postoperative pulmonary complications (PPCs) increase morbidity and mortality of surgical patients, duration of hospital stay and costs. Postoperative atelectasis of dorsal lung regions as a common PPC has been described before, but its clinical relevance is insufficiently examined. Pulmonary electrical impedance tomography (EIT) enables the bedside visualization of regional ventilation in real-time within a transversal section of the lung. Dorsal atelectasis or effusions might cause a ventral redistribution of ventilation. We hypothesized the existence of ventral redistribution in spontaneously breathing patients during their recovery from abdominal and peripheral surgery and that vital capacity is reduced if regional ventilation shifts to ventral lung regions. METHODS: This prospective observational study included 69 adult patients undergoing elective surgery with an expected intermediate or high risk for PPCs. Patients undergoing abdominal and peripheral surgery were recruited to obtain groups of equal size. Patients received general anesthesia with and without additional regional anesthesia. On the preoperative, the first and the third postoperative day, EIT was performed at rest and during spirometry (forced breathing). The center of ventilation in dorso-ventral direction (COVy) was calculated. RESULTS: Both groups received intraoperative low tidal volume ventilation. Postoperative ventral redistribution of ventilation (forced breathing COVy; preoperative: 16.5 (16.0-17.3); first day: 17.8 (16.9-18.2), p < 0.004; third day: 17.4 (16.2-18.2), p = 0.020) and decreased forced vital capacity in percentage of predicted values (FVC%predicted) (median: 93, 58, 64%, respectively) persisted after abdominal surgery. In addition, dorsal to ventral shift was associated with a decrease of the FVC%predicted on the third postoperative day (r = - 0.66; p < 0.001). A redistribution of pulmonary ventilation was not observed after peripheral surgery. FVC%predicted was only decreased on the first postoperative day (median FVC%predicted on the preoperative, first and third day: 85, 81 and 88%, respectively). In ten patients occurred pulmonary complications after abdominal surgery also in two patients after peripheral surgery. CONCLUSIONS: After abdominal surgery ventral redistribution of ventilation persisted up to the third postoperative day and was associated with decreased vital capacity. The peripheral surgery group showed only minor changes in vital capacity, suggesting a role of the location of surgery for postoperative redistribution of pulmonary ventilation. TRIAL REGISTRATION: This prospective observational single centre study was submitted to registration prior to patient enrollment at ClinicalTrials.gov (NCT02419196, Date of registration: December 1, 2014). Registration was finalized at April 17, 2015.

Local Autograft and Strong Pulvertaft Fixation Technique for Reconstruction of a Rerupture of the Extensor Hallucis Longus Tendon: A Case Report.

There are different treatment options for extensor hallucis longus injuries. For primary repair, the end-to-end suture is recommended. The treatment of reruptures or tendon defects is challenging, and a wide range of procedures have been used in this regard, including primary and secondary repairs with and without auto- and allografts. To overcome the disadvantages of second-site morbidity and to achieve high primary stability, we demonstrate a technique using a local tendon graft in combination with a strong Pulvertaft suture technique in a case of rerupture of the extensor hallucis longus tendon.

Active controlled motion in early rehabilitation improves outcome after ankle fractures: a randomized controlled trial.

OBJECTIVE: To evaluate the use of active controlled motion (ACM) after unstable ankle fractures needing initial partial weight-bearing. DESIGN: Prospective randomized controlled trial. SETTING: Inpatient and outpatient clinic. SUBJECTS: A total of 50 patients with unstable ankle fractures and the need for partial weight-bearing for six weeks. INTERVENTIONS: Randomization in two groups: physiotherapy alone or physiotherapy with an additional ACM device. MAIN MEASURES: Follow-up after 6 and 12 weeks. Range of motion, visual analogue scale for foot and ankle (VAS FA), Philip score, Mazur score, American Orthopaedic Foot & Ankle Society (AOFAS) score and dynamic pedobarography. RESULTS: Range of motion was better in the ACM group at six weeks (mean 49° ± 11.1° vs. 41.3° ± 8.1°). Questionnaires revealed better outcome after six weeks in the VAS FA (56 ± 13.7 vs. 40.6 ± 10.5), Mazur score (64.4 ± 12.3 vs. 56.7 ± 11) and AOFAS score (71.2 ± 12 vs. 63.6 ± 8.7) ( P > 0.02 for all). Better outcome after 12 weeks in all questionnaires (VAS FA, 77.7 ± 13.8 vs. 61.4 ± 16.3; Philip score, 79.1 ± 10.9 vs. 60.1 ± 21.7; Mazur score, 83.9 ± 10.7 vs. 73.1 ± 14.1; AOFAS score, 87.5 ± 7.9 vs. 75.2 ± 11.7) ( P < 0.01 for all). Pressure balance was better under the midfoot region after 12 weeks in the ACM group (Δ P 4.4 N vs. 34.0 N; P = 0.01). The ACM group had an earlier return to work after 10.5 (range, 3-17) versus 14.7 (range, 9-26) weeks ( P = 0.02). CONCLUSION: The use of ACM for patients needing initial partial weight-bearing after operatively treated unstable ankle fractures in the first six postoperative weeks leads to better clinical and functional results and an earlier return to work.

[Unusual Case of a a Severely Injured Toddler - Pre- and Early Hospital Treatment and Happy End Despite Obstacles]. / Ungewöhnlicher Fall eines schweren Polytraumas beim Kleinkind ­ Happy End trotz Fallstricken.

A 16-month-old boy suffers a massive trauma (open dislocated pelvic fracture and decollement with haemorrhagic shock) due to a traffic accident. We present the characteristics and obstacles in the prehospital and early hospital emergency care of this severe and rare trauma in a pediatric patient with an emphasis on medical-operational tactics.

How safe is minimally invasive pedicle screw placement for treatment of thoracolumbar spine fractures?

STUDY DESIGN: Prospective analysis of patients who underwent minimally invasive posterior instrumentation. OBJECTIVE: The purpose of this study was to evaluate the safety of minimally invasive pedicle screw placement in patients with unstable thoracic and lumbar spine fractures using the conventional fluoroscopy technique. Although wound infection, haematoma, and new neurological deficit due to screw malplacement remain a common source of morbidity, estimates of their rates of occurrence remain relatively limited. METHODS: 2052 percutaneous pedicle screws in 433 consecutive patients were evaluated. The accuracy of pedicle screw placement was based on evaluation of axial 3-mm slice computed tomography scans. Morbidity and mortality data were collected prospectively. RESULTS: A total of 2029 of 2052 screws (99%) had a good or excellent position. 5 screws (0.2%) showed a higher grade violation of the medial pedicle wall. Seven patients (1.8%) needed revision due to screw malposition (3 pat.), surgical site infection, postoperative haematoma, implant failure (2 pat.), and technical difficulties. CONCLUSIONS: Minimally invasive transpedicular instrumentation is an accurate, reliable, and safe procedure to treat thoracic and lumbar spine fractures.

Comparison of open reduction and internal fixation and primary total hip replacement for osteoporotic acetabular fractures: a retrospective clinical study.

PURPOSE: Treating acetabular fractures with open reduction and internal fixation (ORIF) may lead to poorer outcomes in older patients. As data for osteoporotic acetabular fractures are limited, we compared primary total hip replacement (THR) with ORIF for treating osteoporotic acetabular fractures, including those with posterior column instability. METHODS: All patients with osteoporotic acetabular fractures, treated with ORIF or primary THR from 2005 to 2015, were assessed retrospectively for clinical and radiologic outcomes. Indication criteria for selecting primary THR were evaluated. RESULTS: Twenty-three patients were treated with ORIF and nine with primary THR (performed with an anti-protrusion cage). If the posterior column was unstable, THR was combined with posterior column bridge plating. Indications for THR were the presence of a comminuted fracture pattern, approach-related risk factors for ORIF, and mobilization issues. Biomechanical reconstruction was acceptable with THR. Acetabular component loosening was observed only once. Secondary THR was indicated in 45 % of the ORIF cases. DISCUSSION: ORIF for acetabular fracture in older patients is unsatisfactory and may be even worse for osteoporotic fractures. Immobilization for long-term restricted weight bearing after ORIF is hazardous. Primary THR may enable early post-operative full weight-bearing. Various techniques, affording fixation of the unstable acetabular columns, are described. In THR with an anti-protrusion cage, only dorsal column instability needs to be addressed. CONCLUSION: The described technique achieved sufficient acetabular component stability. Primary THR with an anti-protrusion cage is an advantageous option to ORIF and should be strongly considered for osteoporotic acetabular fractures.

Biomechanical Analysis of the Modified Kessler, Lahey, Adelaide, and Becker Sutures for Flexor Tendon Repair.

PURPOSE: To compare the biomechanical properties of the modified Kessler, Lahey, Adelaide, and Becker repairs, which are marked by either a locking-loop or a cross-lock configuration. METHODS: Ninety-six lacerated porcine flexor tendons were repaired using the respective core suture and an epitendinous repair. Biomechanical testing was conducted under static and cyclic loads. Parameters of interest were 2-mm gap formation force, displacement during different loads, stiffness, maximum force, and mode of failure. RESULTS: The meaningful gap formation occurred in all 4 repairs at similar tension loads without any significant differences. Maximum force was highest in the Becker repair with a considerable difference compared with the modified Kessler and Lahey sutures. The Adelaide repair showed the highest stiffness. Overall, the displacement during cyclic loading demonstrated similar results with an exception between the Lahey and the Adelaide repairs at 10 N load. Failure by suture pull-out occurred in 42% in the modified Kessler, in 38% in the Lahey, and in 4% in the Adelaide repairs. The Becker repair failed only by suture rupture. CONCLUSIONS: The results of our study suggest that the difference between the 4-strand repairs with a cross-lock or a locking-loop configuration is minor in regard to gap formation. A strong epitendinous suture and the application of core suture pretension might prevent differences in gapping. However, the modified Kessler and Lahey repairs had an inferior maximum tensile strength and were prone to early failure caused by the narrow locking loops with their limited locking power. CLINICAL RELEVANCE: We suggest that surgeons should use pre-tension in repaired tendons to improve gap resistance and should avoid narrow locking loop anchoring to the tendon.

[Analysis of a differentiated resuscitation room activation at a national trauma center]. / Analyse einer differenzierten Schockraumalarmierung an einem überregionalen Traumazentrum.

BACKGROUND: In order to continue to efficiently provide both personnel-intensive and resource-intensive care to severely injured patients, some hospitals have introduced individually differentiated systems for resuscitation room treatment. The aim of this study was to evaluate the concept of the A and B classifications in terms of practicability, indications, and potential complications at a national trauma center in Bavaria. METHODS: In a retrospective study, data from resuscitation room trauma patients in the year 2020 were collected. The assignment to A and B was made by the prehospital emergency physician. Parameters such as the injury severity score (ISS), Glasgow outcome scale (GOS), upgrade rate, and the indication criteria according to the S3 guidelines were recorded. Statistical data comparisons were made using t­tests, χ2-tests, or Mann-Whitney U­tests. RESULTS: A total of 879 resuscitation room treatments (A 473, B 406) met the inclusion criteria. It was found that 94.5% of resuscitation room A cases had physician accompaniment, compared to 48% in resuscitation room B assignments. In addition to significantly lower ISS scores (4.1 vs. 13.9), 29.8% of B patients did not meet the treatment criteria defined in the S3 guidelines. With a low upgrade rate of 4.9%, 98% of B patients had a GOS score of 4 or 5. CONCLUSION: The presented categorization is an effective and safe way to manage the increasing number of resuscitation room alerts in a resource-optimized manner.

Immunohistochemical and molecular characterization of the human periosteum.

PURPOSE: The aim of the present study was to characterize the cell of the human periosteum using immunohistological and molecular methods. METHODS: Phenotypic properties and the distribution of the cells within the different layers were investigated with immunohistochemical staining techniques and RT-PCR, focussing on markers for stromal stem cells, osteoblasts, osteoclasts and immune cells. RESULTS: Immunohistochemical results revealed that all stained cells were located in the cambium layer and that most cells were positive for vimentin. The majority of cells consisted of stromal stem cells and osteoblastic precursor cells. The density increased towards the deeper layers of the cambium. In addition, cells positive for markers of the osteoblast, chondrocyte, and osteoclast lineages were found. Interestingly, there were MHC class II-expressing immune cells suggesting the presence of dendritic cells. Using lineage-specific primer pairs RT-PCR confirmed the immunofluorescence microscopy results, supporting that human periosteum serves as a reservoir of stromal stem cells, as well as cells of the osteoblastic, and the chondroblastic lineage, osteoclasts, and dendritic cells. CONCLUSION: Our work elucidates the role of periosteum as a source of cells with a high regenerative capacity. Undifferentiated stromal stem cells as well as osteoblastic precursor cells are dominating in the cambium layer. A new outlook is given towards an immune response coming from the periosteum as MHC II positive immune cells were detected.

Subtrochanteric femoral fractures: influence of patient age on fracture type and mobility.

BACKGROUND: To investigate the potential influence of patient age on fracture type and postoperative mobility in subtrochanteric femoral fractures. METHODS: Data for patients who had suffered subtrochanteric femoral fractures between 2004 and 2009 were analyzed in a retrospective single-center study at a level I trauma center. Age, sex, accident cause, fracture type (Seinsheimer, Russell-Taylor, and AO classifications) and mobility at different time points (pre-trauma, after 3, 6, and 12 months, and current) were collected using the patient files, radiographs, and phone enquiries. The patients were divided into groups aged <65 and ≥65 years. Significant associations between age and fracture type and mobility were investigated using Fisher's exact test, Levene's test, t test, and Mann-Whitney U test. RESULTS: A total of 91 patients were evaluated. There were 38 patients in group I (<65 years) and 53 in group II (≥65 years). The trauma leading to the fracture was greater in group I than in group II (P < 0.01), and group I also had a larger number of concomitant injuries (P < 0.01). There was a smaller proportion of women in group I (38 vs. 75.5 %; P < 0.01). Group II had higher grades in the Russell-Taylor fracture classification (P < 0.05) and more frequently had type A fractures in the AO classification (P < 0.05). No differences between the groups were found when the Seinsheimer classification was applied. With regard to postoperative mobility, there was better mobility in group I after 12 months and at the last follow-up examination (P < 0.01). CONCLUSIONS: Older patients (≥65 years old) more often had type II fractures according to the Russell-Taylor classification, type A fractures in the AO classification, and poorer postoperative mobility over the long term than patients <65 years old.

Medium-term results after complex intra-articular fractures of the tibial plateau.

BACKGROUND: To present the medium-term results of intra-articular, bicondylar AO/OTA classification type C fractures of the tibial plateau in a retrospective study at a level-1 trauma center in 22 patients with 23 fractures. METHODS: Demographic data for the patients and details of current clinical and radiological follow-up findings were obtained to assess range of motion, clinical stability and alignment of the knee, and posttraumatic arthrosis (Kellgren/Lawrence score). Functional outcomes were assessed using the Lysholm score, Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) form. RESULTS: Patients' mean age was 46 years (range 20-67 years). Leading causes of the fractures were high-energy traffic accidents and falls. There were seven C1, seven C2, and nine C3 fractures. ORIF was performed in 20 patients; in two patients an external fixator and in one patient cannulated screws alone were used. In 13/22 patients, an angle-stable locking plate (Less Invasive Stabilization System, LISS) was used for osteosynthesis. The mean follow-up period was 67 months (range 36-109 months). The overall complication rate was 39.1%, including four infections and four cases of pseudarthrosis (17.4%). The average flexion of the injured knee was significantly lower in comparison with the contralateral side (124.9° vs. 135.2°). Knee stability did not differ statistically significantly. Current radiographs revealed no signs of posttraumatic arthrosis in 30.4% of cases, mild signs in 34.8%, clear signs in 26.1%, and severe signs in 13% using the Kellgren and Lawrence scale. The average Lysholm score was 66.2 points, and the average KOOS score was 67.84. One patient was in category A, and 2 were in category B in the IKDC overall categories, whereas 5 patients were in category C and 14 were even in category D. CONCLUSIONS: Complex articular tibial plateau fractures are associated with a high rate of complications, continue to have a severe impact on function in the injured knee, lead to early post-traumatic arthrosis, and result in long-lasting subjective symptoms for the patients.

Clinical outcome and changes in gait pattern after pilon fractures.

PURPOSE: Axial burst fractures of the distal tibia are challenging to treat and often lead to restricted function of the lower limb. The purpose of this study was to investigate the clinical outcome and changes in gait pattern in such patients. METHODS: Thirty-five patients in a level 1 trauma centre were followed up clinically and by gait analysis. The American Orthopaedic Foot and Ankle Society (AOFAS), visual analogue scale (VAS) foot and ankle scale and Phillips scores were applied. Dynamic pedography (emed-M; Novel, Germany) with analyses of load, pressure and force-time integral were undertaken to investigate possible changes in gait pattern. RESULTS: Mean follow-up was 50 (19-100) months. Mean AOFAS, VAS foot and ankle and Phillips scores were 65, 63 and 55 points, respectively. There were clear correlations between fracture severity in the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification and functional outcome in AOFAS (-0.63; p < 0.01), VAS foot and ankle scale (-0.56; p < 0.01) and Phillips (-0.64; p < 0.01) scores. There was a high correlation of 0.74 (p < 0.01) between the severity of the injury in the AO-classification and onset of post-traumatic arthrosis. Dynamic pedography revealed lesser load bearing for the total foot, medial foot, heel, first metatarsal and medial forefoot for the affected limb, and increased load bearing was seen in the lateral midfoot region. CONCLUSIONS: Fractures of the tibial pilon lead to restricted function of the lower limb. Clinical outcome correlates with fracture severity in the AO classification, the onset of post-traumatic arthrosis and changes in gait patterns.

Results of dynamic pedobarography following surgically treated intra-articular calcaneal fractures.

OBJECTIVE: To investigate the clinical outcome and gait analysis findings by dynamic pedobarography in patients following surgically treated single, closed, dislocated intra-articular calcaneal fractures. DESIGN: Retrospective single-center study with 26 patients. The average follow-up period was 34 months (range 18-61 months). We used the Zwipp score and a score based on a visual analog scale (VAS) to assess the subjective and objective clinical outcome. Dynamic pedobarography (EMED-M, 38 × 42 cm, four sensors per square centimeter, 50 Hz; Novel GmbH., Munich, Germany) was performed to retrieve gait patterns. Analysis was performed using the Emed-Software (Novel GmbH., Munich, Germany). RESULTS: For the Zwipp score (±200 points), the average was +54.4 points (±48.2); for the VAS score (0-100 points), the average was 58.3 points (±24.3). There was limited mobility in the upper and lower ankle joint. Pedobarography showed a clearly disturbed gait with increased pressure for the fractured side (157 vs. 119 kPa) in the midfoot region (71.8 vs. 68 kPa) and under fifth metatarsal bone (234 vs. 160 kPa). The gait line was lateralized. The force-time-integral (fractured vs. healthy side) showed significant differences for the medial (18 vs. 7 N s) and lateral (61 vs. 36 N s) midfoot region. CONCLUSIONS: We found only an average clinical outcome and clear pathological gait patterns in our cohort with lateralization of the gait line.

Web-based eHealth Clinical Decision Support System as a tool for the treat-to-target management of patients with systemic lupus erythematosus: development and initial usability evaluation.

BACKGROUND: Treat-to-target (T2T) is a therapeutic strategy currently being studied for its application in systemic lupus erythematosus (SLE). Patients and rheumatologists have little support in making the best treatment decision in the context of a T2T strategy, thus, the use of information technology for systematically processing data and supporting information and knowledge may improve routine decision-making practices, helping to deliver value-based care. OBJECTIVE: To design and develop an online Clinical Decision Support Systems (CDSS) tool "SLE-T2T", and test its usability for the implementation of a T2T strategy in the management of patients with SLE. METHODS: A prototype of a CDSS was conceived as a web-based application with the task of generating appropriate treatment advice based on entered patients' data. Once developed, a System Usability Score (SUS) questionnaire was implemented to test whether the eHealth tool was user-friendly, comprehensible, easy-to-deliver and workflow-oriented. Data from the participants' comments were synthesised, and the elements in need for improvement were identified. RESULTS: The beta version web-based system was developed based on the interim usability and acceptance evaluation. 7 participants completed the SUS survey. The median SUS score of SLE-T2T was 79 (scale 0 to 100), categorising the application as 'good' and indicating the need for minor improvements to the design. CONCLUSIONS: SLE-T2T is the first eHealth tool to be designed for the management of SLE patients in a T2T context. The SUS score and unstructured feedback showed high acceptance of this digital instrument for its future use in a clinical trial.

VEGF improves skeletal muscle regeneration after acute trauma and reconstruction of the limb in a rabbit model.

BACKGROUND: Complicated tibial fractures with severe soft tissue trauma are challenging to treat. Frequently associated acute compartment syndrome can result in scarring of muscles with impaired function. Several studies have shown a relationship between angiogenesis and more effective muscle regeneration. Vascular endothelial growth factor (VEGF) is associated with angiogenesis but it is not clear whether it would restore muscle force, reduce scarring, and aid in muscle regeneration after acute musculoskeletal trauma. QUESTIONS/PURPOSES: Therefore, we asked whether local application of VEGF (1) restores muscle force, (2) reduces scar tissue formation, and (3) regenerates muscle tissue. METHODS: We generated acute soft tissue trauma with increased compartment pressure in 22 rabbits and shortened the limbs to simulate fracture débridement. In the test group (n = 11), a VEGF-coated collagen matrix was applied locally around the osteotomy site. After 10 days of limb shortening, gradual distraction of 0.5 mm per 12 hours was performed to restore the original length. Muscle force was measured before trauma and on every fifth day after trauma. Forty days after shortening we euthanized the animals and histologically determined the percentage of connective and muscle tissue. RESULTS: Recovery of preinjury muscle strength was greater in the VEGF group (2.4 N; 73%) when compared with the control (1.8 N; 53%) with less connective and more muscle tissue in the VEGF group. The recovery of force was related to the percentage of connective tissue versus muscle fibers. CONCLUSIONS: Local application of VEGF may improve restoration of muscle force by reducing connective tissue and increasing the relative amount of muscle fibers. CLINICAL RELEVANCE: VEGF may be useful to improve skeletal muscle repair by modulating muscle tissue regeneration and fibrosis reduction after acute trauma.

Higher stability with locking plates in hand surgery? Biomechanical investigation of the TriLock system in a fracture model.

PURPOSE: The aim of this study was to determine the biomechanical characteristics of locking plates with the TriLock system with different design and screw settings compared to a non-locking plate in a diaphyseal metacarpal fracture. METHODS: Oblique diaphyseal shaft fractures in porcine metacarpal bones were created in a biomechanical fracture model. After reduction they were fixed with three different locking plates with the TriLock interlocking mechanism or a non-locking linear plate in mono- or bicortical screw fixations. In load to failure tests the maximum load and stiffness were measured. RESULTS: For linear plates, the maximum load was higher for the non-locking plate compared with the locking plate. The maximum load could be increased for the locking plates using a double-row design and a higher screw number. No differences were found for the stiffness between all groups. In contrast to the non-locking plate, the mode of failure of the locking plates in many cases (86 %) was a loss of the interlocking mechanism. CONCLUSIONS: The results suggest that the locking plates with the TriLock system achieve no higher stability compared to a non-locking plate in load to failure tests. Adaptions to increase the stability of the interlocking mechanism are desirable.

Effective combination of bone substitute and screws in the jail technique: a biomechanical study of tibial depression fractures.

PURPOSE: The aim of this study was to investigate a new drillable calcium phosphate cement (Norian drillable Synthes GmbH) as a bone substitute either alone or in combination with screws in the jail technique (Petersen et al. Unfallchirurg Mar 109(3):219-234, 2006; Petersen et al. Unfallchirurg Mar 109(3):235-244, 2006) with regard to the primary stability in lateral tibial depression fractures. METHODS: Lateral depression fractures of the tibial plateau were created in a biomechanical fracture model. After reduction they were stabilised with bone substitute (group one), bone substitute with additional four screws in the jail technique (group two) or four screws only (group three). Displacement under cyclic loading, stiffness and maximum load in load-to-failure tests were determined. RESULTS: The groups with the bone substitute showed a lower displacement of the depressed articular fragment under cyclical loading and a higher stiffness. The maximum load was higher for the groups with screws. CONCLUSIONS: Only the combination of bone substitute and screws prevented secondary loss of reduction and, at the same time, provided enough stability under maximum load.

Cysteine-rich matricellular protein improves callus regenerate in a rabbit trauma model.

PURPOSE: Open fractures with severe soft-tissue trauma are predisposed to poor bone healing. The vital coupling between osteo- and angiogenesis is disturbed. Cysteine-rich protein 61 (CYR61) is an angiogenic inducer promoting vascularisation. However, little is known about the effect of CYR61 on the callus regenerate after acute musculoskeletal trauma. Therefore, our aim was to determine whether local administration of CYR61: (1) has an influence on callus formation and remodelling, (2) increases bone volume and (3) partially restores callus stability. METHODS: A musculoskeletal trauma was created in 20 rabbits. To simulate fracture-site debridement, the limb was shortened. In the test group, a CYR61-coated collagen matrix was locally applied around the osteotomy. After ten days, gradual distraction was commenced (0.5 mm/12 h) to restore the original length. New bone formation was evaluated histomorphometrically, radiographically and biomechanically. RESULTS: Osseus consolidation occured in all animals. Average maximum callus diameter was higher in the test group [1.39 mm; standard deviation (SD) = 0.078 vs 1.26 mm (SD = 0.14); p = 0.096]. In addition, bone volume was higher (p = 0.11) in the test group, with a mean value of 49.73 % (SD = 13.68) compared with 37.6 % (SD = 5.91). Torsional strength was significantly higher (p = 0.005) in the test group [105.43 % (SD = 31.68 %) vs. 52.57 % (SD = 24.39)]. Instead, stiffness of the newly reconstructed callus decreased (64.21 % (SD = 11.52) vs. 71.30 % (SD = 32.25) (p = 0.81)). CONCLUSIONS: CYR61 positively influences callus regenerate after acute trauma, not only histologically and radiographically but also biomechanically, most probably by a CYR61-associated pathway.

Surgical Fixation of Calcaneal Beak Fractures-Biomechanical Analysis of Different Osteosynthesis Techniques.

The calcaneal beak fracture is a rare avulsion fracture of the tuber calcanei characterized by a solid bony fragment at the Achilles tendon insertion. Treatment usually requires osteosynthesis. However, lack of biomechanical understanding of the ideal fixation technique persists. A beak fracture was simulated in synthetic bones and assigned to five different groups of fixation: A) 6.5-mm partial threaded cannulated screws, B) 4.0-mm partial threaded cannulated screws, C) 5.0-mm headless cannulated compression screws, D) 2.3-mm locking plate, and E) 2.8-mm locking plate. Different traction force levels were applied through an Achilles tendon surrogate in a material-testing machine on all stabilized synthetic bones. Outcome measures were peak-to-peak displacement, total displacement, plastic deformation, stiffness, visual-fracture-line displacement, and mode of implant failure. The 2.3- and 2.8-mm plating groups showed a high drop-out rate at 100 N tension force and failed under higher tension levels of 200 N. The fracture fixation using 4.0-mm partial threaded screws showed a significantly higher repair strength and was able to withhold cyclic loading up to 300 N. The lowest peak-to-peak displacement and the highest load-to-failure and stiffness were provided by fracture fixation using 6.5-mm partial threaded cannulated screws or 5.0-mm headless cannulated compression screws. As anticipated, large 6.5-mm screw diameters provide the best biomechanical fixation. Surprisingly, the 5.0-mm headless cannulated compression screws yield reliable stability despite the absent screw head and washer. When such large screws cannot be applied, 4.0-mm screws also allow reasonable fixation strength. Plate fixation should be implemented with precaution and in combination with a restrictive postoperative motion protocol. Finally, clinical cases about the surgical application and recovery are included.