Bone healing of critical size defects of the rat femur after the application of bone marrow aspirate and two different rh-BMP7 concentrations.

BACKGROUND: It is known that the application of growth factors can enhance fracture healing in defect fractures. The role of bone marrow aspirate (BMA) in combination with BMP-7 and the dosage of rh BMP-7 are still under discussion. Our hypothesis was that the combination of rh-BMP-7 with BMA can heal bone defects more effectively than rh-BMP-7 alone. METHODS: Twenty-eight rats obtained a 5 mm critical size defect in the diaphysis of the right femur which was stabilized by a plate. Rh-BMP-7 was applied at 10 and 200 µg either with collagen or together with collagen and BMA. Collagen only and collagen with BMA served as control groups. Blood flow was assessed by laser Doppler flowmetry in regular time intervals until euthanasia. Callus formation and bone density were measured by micro-computed tomography and biomechanical stability was evaluated by torsional testing at 4 weeks, postoperatively. RESULTS: Blood flow increased at the operated side after surgery until the second postoperative week independent of treatment. Animals treated with high dose BMP-7 showed significantly (p = 0.001) increased mechanical stiffness independent of BMA treatment. Failure loads were lowest for the two control groups (p = 0.001). The reduction of the BMP-7 dose led to less callus tissue and lower biomechanical stability. BMA did not show significant influence on bone healing. CONCLUSION: The combination of an rhBMP-7 dose that would be equivalent to a dose used clinically in humans with bone marrow aspirate does not heal a critical bone defect more effectively than the same rhBMP-7 dose alone.

Development of heterotopic ossifications, blood markers and outcome after radiation therapy in spinal cord injured patients.

STUDY DESIGN: Retrospective study. OBJECTIVES: This study was implemented to detect risk factors for the developing of heterotopic ossifications (HOs) in spinal cord injury (SCI) patients. SETTING: This study was conducted in Murnau, Germany. METHODS: All patients from 2008-2012 with acute SCI were routinely examined by ultrasound of the hips every 2 weeks. The sub group of SCI patients suffering of HO of the hips were extracted and the incidence of developing an HO was calculated. Parameters like age, level of injury, ASIA Impairment Scale (AIS), duration time of accident until diagnosis of HO, Brooker stage, localization of HO (magnetic resonance imaging (MRI)) and symptoms like thrombosis, emboli, decrease of range of motion (ROM), dermal symptoms, swelling, increase in D-Dimere level, were evaluated. Also accompanying injuries of the brain, lung and extremities were recorded. RESULTS: From January 2008 until January 2012, 575 patients with an acute and traumatic SCI were treated in our Department. During this period 32 HOs were detected in the muscles surrounding the hip. In 10 cases a single side and in 22 cases both sides were affected. A total of 26 patients were detected showing up a Brooker 0, two patients Brooker 1, and five patients a Brooker stage >2. The adductor muscles showed an edema in 19 cases and the quadriceps muscles were affected in 15 cases. 26% of all SCI patients showed AIS A status, but in patients who developed HO, 64% have had an AIS A status. 19% of patients with a HO were AIS B and 9.5% showed an AIS C and D. Regarding the level of injury the distribution of patients suffering of HO was comparable to the distribution of SCI patients without HO. In mean HO were detected 9 weeks after SCI and no new HO were found after the 22nd (n=1) week of injury. Clinical symptoms such as swelling, pain, redness or decrease in ROM or increase in D-Dimere levels were seen in 24 cases. Accompanying injuries like brain injury and lung contusions were found in 83% of patients developing HO. The incidence of thrombosis was comparable to SCI patients without HO. One patient with no accompanying injuries or clinical symptoms was detected by routinely performed ultrasound. CONCLUSIONS: The risk of developing HO in patients with traumatic SCI is 5.5% but increases when accompanying injuries of the brain and lung occur. Patients with a neurological status of AIS A must also be quoted as risk patients. When considering the described risk factors and clinical symptoms, 96% of all HO can be detected.

[Stability of volar fixed-angle plating for distal radius fractures. Failure modes in osteoporotic bone]. / Die Stabilität von distalen Radiusfrakturen mit volaren winkelstabilen Plattenosteosynthesen. Versagensmechanismen im osteoporotischen Knochen.

BACKGROUND: Distal radius fractures continue to show significant complication rates after operative treatment with locked plating. Failure occurs by screw loosening or screw penetration in the distal fragment. Placement of additional screws may enhance the stiffness of fracture fixation. The aim of this study was to determine the fatigue properties of different screw configurations in distal radius plate osteosynthesis with biomechanical tests and finite element analysis (FEA). MATERIAL AND METHODS: Unstable distal radius fractures were created in 12 human cadaveric bone specimens and were fixed with volar locking plates. Group 4SC was fixed with four screws in the distal row and group 6SC with two additional screws the row below. Dynamic loading was applied physiologically. The radial shortening, the angulation of the distal fragment and the failure mechanism were determined by experimental tests and were further elucidated by FEA. RESULTS: Group 6SC showed a significantly lower radial shortening and inclination. Breakage of the screws within the plate was noted in group 4SC, while moderate screw penetration was observed in group 6SC. FEA confirmed the biomechanical tests. In group 4SC elevated von Mises strain in the locking mechanism explained the inclination of the screws and the distal fragment. The elastic strain in group 6SC was increased at the screw-bone interface which explained the resulting screw penetration. CONCLUSION: The failure mechanism in volar plating of distal radius fractures depended on the number of screws and their configuration. Using two more screws increases construct stiffness and angular stability under dynamic loading. However, increased stiffness also promoted screw penetration mainly in osteoporotic bone. Compared to screw penetration, loss of reposition and inclination of the distal fragment observed in the 4SC configuration is more likely to result in clinical complications.

Distal radius fracture fixation with volar locking plates and additional bone augmentation in osteoporotic bone: a biomechanical study in a cadaveric model.

BACKGROUND: Fractures of the distal radius represent the most common fractures in adults. Volar locked plating has become a popular method for treating these fractures, but has been subject to several shortcomings in osteoporotic bone, such as loss of reduction and screw purchase. In order to overcome these shortcomings, cement augmentation has been proposed. METHODS: AO-type 23-A3.3 fractures were made in 8 pairs of fresh frozen osteoporotic cadaveric radial bones. All specimens were treated with volar plating, and divided into cement augmentation or non-augmentation groups (n = 8/group). Constructs were tested dynamically and load to failure, construct-stiffness, fracture gap movement and screw cutting distance were measured. RESULTS: Cement augmentation resulted in a significant increase in cycles and load to failure, as well as construct stiffness at loads higher than 325 N. When compared to the non-augmented group, fracture gap movement decreased significantly at this load and higher, as did screw cutting distance at the holes of the ulnar column. The cycles to failure depend on the BMD in the distal region of the radius. CONCLUSION: Cement augmentation improves biomechanical properties in volar plating of the distal radius.

Reamed intramedullary nailing of diaphyseal tibial fractures: comparison of compression and non-compression nailing.

BACKGROUND: Modern intramedullary implants provide the option to perform compression at the fracture gap in long bone fractures via a compression screw mechanism. The aim of this study was to assess if the application of interfragmentary compression in the intramedullary nailing of tibia fractures could increase the union rate and speed of fracture healing. METHODS: Sixty-three patients who suffered from an AO-type 42-A3 or 42-B2 fracture that was treated by reamed intramedullary nailing between 2003 and 2008 were included in this retrospective study. Twenty-five patients were treated with dynamic interlocking without compression while 38 were treated with compression nailing. The compression load of the dynamic proximal screw was calculated by postoperative X-ray and radiographs taken four weeks after operation. Healing was assessed by radiological evaluation until the completion of bony healing or the disappearance of clinical symptoms. Nonunion was defined as the absence of radiological union and the persistence of clinical symptoms after six months. RESULTS: Postoperative compression was applied at a mean load of 1,852 N, and 980 N remained after four weeks. In the compression group, 19 open and 19 closed fractures occurred. In the non-compression group, 25 patients were included (14 closed and 11 open cases). Active compression decreased healing time significantly. Nonunion occurred in one compression patient and three non-compression patients. CONCLUSION: The results show that additional compression of the fracture gap can improve healing outcome in simple transverse tibial shaft fractures treated with reamed nailing.

Functional outcome of patients 12 and 48 weeks after acute traumatic tetraplegia and paraplegia: data analysis from 2004-2009.

OBJECTIVES: During the first rehabilitation of patients with traumatic spinal cord injuries (SCIs), professional skills are learned, which can be objectified in an independent measurement score. The aims of this study were to record the skills of patients 12 and 48 weeks after acute trauma and perform an analysis of the data to identify provisions of importance. METHODS: All patients from 2004 to 2009 who experienced traumatic SCI were included in this investigation. Data recording were accomplished by the European Multi-Centre Study about Spinal Cord Injury (EMSCI) databank. Patients were divided into tetraplegia and paraplegia groups. Parameters were age at injury, the American Spinal Injury Association-Score, level of lesion and spinal cord independence measure (SCIM-Score) 12 and 48 weeks after traumatic spinal cord lesion. A questionnaire was also added to help clarify where deficiencies were prevalent. RESULTS: Data analysis of 103 tetraplegic and 110 paraplegic patients showed no correlation between the ASIA score, level of lesion, age and SCIM score. On average, tetraplegic patients had a SCIM score of 43 points 12 weeks after treatment, with 81% showing an increase to 58 points after 48 weeks. Paraplegic patients showed an average SCIM score of 60 points after 12 weeks, with 71% experiencing an increase to 71 points after 48 weeks. In all, 9% of tetraplegic patients and 19% of paraplegic patients experienced a decrease of SCIM points after 48 weeks, which occurred mainly in the bladder and intestinal control subgroups. Results of the questionnaire were not helpful for clarifying the location of the deficiencies. CONCLUSION: Most of the patients experienced an increase of SCIM points 48 weeks after traumatic SCI. However, data also showed that, especially in paraplegic patients, special attention must be given to bladder and intestinal management to avoid negative late-term consequences.

Biomechanical comparison of two locking plate systems for the distal tibia.

BACKGROUND: Distal tibia fractures are known to be difficult to stabilize and nonunions often occur because of a relative instability of the fragments. Therefore, it was of interest to ascertain how different locking plates behave regarding stiffness and interfragmentary movement in comminuted distal tibia fractures. METHODS: A locked medial plate (AxSOS) for the medial distal tibia and a locked medial plate (LCP) for the distal medial tibia were compared biomechanically under compression and torsional load. The tibiae were osteotomized in distal intersection between 4/5 and 5/5, with a gap of 10 mm after instrumentation. For compression force, a load of 350 N was applied and for torsion, a torque of 0-10 Nm and back to 0 over -5-Nm intervals was performed. Stiffness was calculated from the machine data and interfragmentary movement was measured with an optoelectronic measurement device. RESULTS: Under compression load, the stiffness showed no significant differences between the AxSOS plate compared to the LCP. Significant differences were seen in the interfragmentary movement, where the LCP showed 1.03 mm compared to 0.6 mm for the AxSOS plate. In torsional testing, the AxSOS plate showed significantly higher stiffness than the LCP. The AxSOS plate and the LCP showed similar values for interfragmentary movement under torsional load. CONCLUSION: The treatment of distal tibia fractures with angle-stable medial AxSOS plate showed less interfragmentary movement and higher stiffness than fracture fixation with a locked medial LCP. Even if there are no significant differences in torsional testing, plating of the distal tibia should be performed with a steel plate from the biomechanical view.

[Percutaneous administration of recombinant human bone morphogenetic protein-7 (rhBMP-7) after callus distraction. Two case reports]. / Perkutane Applikation von rekombinantem humanem Bone Morphogenetic Protein-7 (rhBMP-7) nach Kallusdistraktion. Zwei Fallberichte.

Two cases of increased bone density after callus distraction are described following percutaneous administration of 3.5 mg recombinant bone morphogenetic protein-7 (rhBMP-7). Both patients underwent segmental resection and segmental transport for osteomyelitis of the long bones (femur and tibia) but no callus maturation occurred. After percutaneous administration of rhBMP-7 the callus density increased in both cases.

Fracture healing after reamed and unreamed intramedullary nailing in sheep tibia.

Intramedullary nailing is a well-established method for stabilisation of long-bone shaft fractures. It is still a controversy as to whether the procedure should be done by an unreamed or reamed technique. In the present animal study, 24 sheep were treated with intramedullary nailing. Midshaft fractures (Arbeitsgemeinschaft für Osteosynthese (AO) type 42-A2/3) were created. Eight sheep were treated with an unreamed nailing technique (UN), a further eight sheep underwent tibia nailing by the reamed technique using the conventional AO reaming system (RC) and in a further eight sheep, reamed nailing was performed using an experimental reaming system (RE). Intra-operatively, the intramedullary pressure was measured and, during a healing time of 10 weeks, the growth of callus formation was labelled with fluorescence markers after 4 and 6 weeks. After 10 weeks, the animals were euthanised and the quality of fracture healing was determined by recording stiffness in torsion, antero-posterior and mediolateral bending and the load at yield. In addition, the callus formation at the fracture zone was evaluated by fluorescence microscopy and macroradiographs. The results showed a decrease of intramedullary pressure when reamed nailing was performed with the RE (72.5 mmHg) system compared with the conventional AO reaming system (227 mmHg). Mechanical testing did not reveal any significant differences either for torsional or bending stiffness or for load at yield for any of the three procedures. Histological evaluation showed a similar callus formation for the UN group and the RE group. Callus formation in the UN (65 mm(2)) and RE (63 mm(2)) groups showed a higher increase during the first 6 weeks than those treated with the conventional AO reaming system (27 mm(2)). This means that, especially during the first weeks of fracture healing, damage to the bone by the reaming process can be reduced by reaming with a reaming device with lowered cutting flutes and smaller drive-shaft diameter. Intramedullary pressure can be significantly reduced by using reaming systems with reduced drive-shaft diameters and deepened cutting flutes. In the early phase of fracture healing, callus formation can be influenced positively when using the RE system.

A biomechanical evaluation of orthopaedic implants for hip fractures by finite element analysis and in-vitro tests.

The aim of this study was to test the hypothesis that a reinforced gamma nail for the fixation of subtrochanteric fractures would experience less stress during loading compared with a common gamma nail. The issue of whether the use of the stronger implant would result in more stress shielding in the surrounding bone was also addressed. A finite element analysis (FEA) of a synthetic bone was employed to calculate the stress distribution in implant and bone for two fracture types (AO 31-A3.1 and AO 31-A3.3). The FEA was validated by mechanical tests on six synthetic femurs. To test the hypothesis in vitro, mechanical tests on six pairs of fresh-frozen human femurs were conducted. The femurs were supplied with a common or a reinforced gamma nail in a cross-over study design. Strains were measured on the nail shaft to quantify the loading of the nail. The FEA resulted in 3-51 per cent lower stresses for the reinforced gamma nail. No increase in stress shielding could be observed. In the in-vitro tests, the reinforced gamma nail experienced less strain during loading (p < 0.016). The study demonstrated the benefit of a reinforced gamma nail in subtrochanteric fractures. It experienced less stress but did not result in more stress shielding.

Pulmonary fat embolism after reamed and unreamed nailing of femoral fractures.

BACKGROUND: To determine whether reamed or unreamed intramedullary nailing of femoral fractures results in higher incidence of pulmonary fat embolism, three different methods of intramedullary nailing were compared in sheep. To analyze the presence of bone marrow fat embolism in pulmonary arteries, histological evaluation was undertaken using a quantitative computer-assisted measurement system. METHODS: In this experimental model of 27 female Swiss alpine sheep, an osteotomy of the proximal femur was conducted in each animal. Then, the animals were divided into three groups according to the method of treatment: two different reamed intramedullary nailing techniques and an unreamed nailing technique were used. In the first group "ER" (experimental reamer; n=9), the nail was inserted after reaming with an experimental reamer; in the second group "CR" (conventional reamer; n=7), the intramedullary nail was inserted after reaming with the conventional AO-reamer. In the third group "UN" (unreamed; n=8) unreamed nailing was performed. During the operation procedure intramedullary pressure was measured in the distal fragment. After sacrificing the animals, quantitative histological analyses of bone marrow fat embolism in pulmonary arteries were done using osmium tetroxide fixation and staining of the fat. RESULTS: The measurement of intramedullary pressure showed significantly lower values for reamed nailing than for the unreamed technique. The quantitative histological evaluation of lung vessels concerning bone marrow fat embolism revealed a statistically significant difference between reamed and unreamed insertion of the nail: 7.77%±6.93 (ER) and 6.66%±5.61 (CR) vs. 16.25%±10.05 (UN) (p<0.05) of the assessed lung vessels were filled with fat emboli. However, no difference was found between the traditional and experimental reamer. CONCLUSIONS: Intramedullary nailing after reaming is a safe procedure with low systemic embolisation when compared to the unreamed insertion of the nail.