Survived traumatic hemipelvectomy with salvage of the limb in a 14 months old toddler.

We report on a 14 months old toddler who sustained a traumatic hemipelvectomy by being crushed between a car and a stone wall. After stabilization in the resuscitation room he was treated operatively by laparotomy, osteosynthesis of the pelvic ring, reconstruction of the both external iliac vessels and the urethra and reposition of the testicles. After 66 days he was discharged into rehabilitation. Implants were removed after eight months. 20 months after the injury, the leg was plegic, initial radiological signs of femoral head necrosis showed up but the infant was able to walk with an orthesis and a walker. Up to our knowledge, this is the youngest patient described in the literature with a survived traumatic hemipelvectomy and salvaged limb.

Biomechanical analysis of different osteosyntheses and the combination with bone substitute in tibial head depression fractures.

BACKGROUND: Tibial head depression fractures demand a high level of fracture stabilization to prevent a secondary loss of reduction after surgery. Elderly individuals are at an increased risk of developing these fractures, and biomechanical investigations of the fractures are rare. Therefore, the aim of this study was to systematically analyze different types of osteosyntheses in combination with two commonly used bone substitutes. METHODS: Lateral tibial head depression fractures were created in synthetic bones. After reduction, the fractures were stabilized with eight different treatment options of osteosynthesis alone or in combination with a bone substitute. Two screws, 4 screws and a lateral buttress plate were investigated. As a bone substitute, two common clinically used calcium phosphate cements, Norian® Drillable and ChronOS™ Inject, were applied. Displacement of the articular fracture fragment (mm) during cyclic loading, stiffness (N/mm) and maximum load (N) in Load-to-Failure tests were measured. RESULTS: The three different osteosyntheses (Group 1: 2 screws, group 2: 4 screws, group 3: plate) alone revealed a significantly higher displacement compared to the control group (Group 7: ChronOS™ Inject only) (Group 1, 7 [p < 0.01]; group 2, 7 [p = 0.04]; group 3, 7 [p < 0.01]). However, the osteosyntheses in combination with bone substitute exhibited no differences in displacement compared to the control group. The buttress plate demonstrated a higher normalized maximum load than the 2 and 4 screw osteosynthesis. Comparing the two different bone substitutes to each other, ChronOS™ inject had a significantly higher stiffness and lower displacement than Norian® Drillable. CONCLUSIONS: The highest biomechanical stability under maximal loading was provided by a buttress plate osteosynthesis. A bone substitute, such as the biomechanically favorable ChronOS™ Inject, is essential to reduce the displacement under lower loading.

Bone substitute first or screws first? A biomechanical comparison of two operative techniques for tibial-head depression fractures.

BACKGROUND: The aim of this study was to investigate a drillable and injectable bone substitute (calcium phosphate cement) and the operative technique enabled by the drillable option in a new biomechanical fracture model for tibial depression fractures in synthetic bones. MATERIALS AND METHODS: Lateral depression fractures of the tibial plateau (AO 41-B2, Schatzker III) were created in a biomechanical fracture model in three different synthetic bones (Sawbone 3401, Synbone 1110/1116). Reproducible fractures were generated employing Synbone 1110, which exhibited a comparable strength to human osteoporotic bones and was used for the further experiments. After reduction of the fractures, the stabilization was performed with two different operative techniques. In group 1, first an osteosynthesis with four screws was performed and then the metaphyseal defect was filled up with calcium phosphate cement (Norian drillable). In group 2, initially the filling up with Norian drillable was done enabling a complete filling of the defect, followed by placing of the screws. Displacement under cyclic loading with 250 N for 3,000 cycles, stiffness, and maximum load in load-to-failure tests were determined. RESULTS: A comparison of the two operative techniques of stabilization showed a distinctly lower displacement and higher stiffness for group 2 when the defect was filled up first. For the maximum load, no significant differences could be demonstrated. CONCLUSIONS: A complete filling of the defect by first applying the calcium phosphate cement significantly reduces the secondary loss of reduction of the depression fracture fragment under cyclic loading with a clinically relevant partial weight bearing. The beneficial effects of drillable calcium phosphate cement may also be transferable to defects other than tibial-head depression fractures.

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.

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.

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.

A contoured locking plate for distal fibular fractures in osteoporotic bone: a biomechanical cadaver study.

OBJECTIVE: Fixation of ankle fractures in elderly patients is associated with reduced stability conditioned by osteoporotic bone. Therefore, fixation with implants providing improved biomechanical features could allow a more functional treatment, diminish implant failure and avoid consequences of immobilisation. MATERIALS AND METHODS: In the actual study, we evaluated a lateral conventional contoured plate with a locking contoured plate stabilising experimentally induced distal fibular fractures in human cadavers from elderly. Ankle fractures were induced by the supination-external rotation mechanism according to Lauge-Hansen. Stage II fractures (AO 44-B1) were fixed with the 2 contoured plates and a torque to failure test was performed. Bone mineral density (BMD) was measured by quantitative computed tomography to correlate the parameters of the biomechanical experiments with bone quality. RESULTS: The locking plate showed a higher torque to failure, angle at failure, and maximal torque compared to the conventional plate. In contrast to the nonlocking system, fixation with the locking plate was independent of BMD. CONCLUSION: Fixation of distal fibular fractures in osteoporotic bone with the contoured locking plate may be advantageous as compared to the nonlocking contoured plate. The locking plate with improved biomechanical attributes may allow a more functional treatment, reduce complications and consequences of immobilisation.

Subtrochanteric fracture: a rare but severe complication after screw fixation of femoral neck fractures in the elderly.

Cannulated screw fixation is a minimal invasive technique to treat undisplaced femoral neck fractures. It is the preferred method in elderly patients who often suffer co-morbidities. There is scarce literature on subtrochanteric femoral fracture as a complication of cannulated screw fixation of a femoral neck fracture. This complication occurred, without an adequate trauma, in two of 35 patients (5.7%) in this retrospective study of patients older than 65 years (mean age: 77 years) who were treated with cannulated screws for an undisplaced femoral neck fracture between 2004 and 2009. We reviewed the literature for the incidence of this complication and possible predisposing factors. The overall incidence reported in literature is 2.4-4.4% (mean: 2.97%). Despite a broad use of this type of osteosynthesis, the literature does not provide clear biomechanical or clinical indications for optimal screw placement to avoid this complication. Considering the literature and our personal results, surgeons should be aware of this severe complication; they may opt for a different implant in the very old, osteoporotic patient with an undisplaced femoral neck fracture.

Downregulation of beta-catenin and transdifferentiation of human osteoblasts to adipocytes under estrogen deficiency.

BACKGROUND AND AIM: Postmenopausal osteoporosis, caused by estrogen deficiency, is characterized by the structural deterioration of bone accompanied by an increase in bone marrow adipocytes. Transgenic animal models have shown that there is a reciprocal relationship between osteoblastogenesis and adipogenesis in vivo. The present study investigated whether the estrogen and the canonical Wnt signaling pathways are linked together and regulate the phenotype and function, differentiation and proliferation of human osteoblasts using an in vitro estrogen-deficiency model. METHODS: Human osteoblasts (hFOB 1.19) and fulvestrant, an estrogen receptor blocker, were used to mimic estrogen deficiency in vitro. Osteogenic and adipogenic differentiation was measured by using specific stains and microscopy, as well as by measuring the expression of bone cell-specific markers with reverse transcription polymerase chain reaction. Expression of estrogen receptor-alpha (ERalpha) and beta-catenin was detected in Western blots and by immunoprecipitation. RESULTS: The cells expressed the 46-kDa and the 77-kDa ERalpha isoforms and beta-catenin. Fulvestrant reduced expression of ERalpha and beta-catenin. beta-Catenin was co-immunoprecipitated with ERalpha, indicating that these two proteins form a new signaling complex and transcription factor. In addition, it induced intracellular lipid droplet accumulation and downregulation of bone cell markers, indicating adipocyte differentiation.