Early versus late surgery of thoracic spine fractures in multiple injured patients: is early stabilization always recommendable?

BACKGROUND CONTEXT: Many institutions' retrospective studies investigated the effect of the timing of surgery on outcomes of polytraumatized patients with severe lesions of the thoracic spine and mainly found a better outcome for patients who were operated on less than 72 hours posttrauma. PURPOSE: We conducted a prospective study in a Level I trauma center to validate the retrospective data and to investigate other variables, in addition to the timing of surgery that may influence patient outcomes. STUDY DESIGN: Prospective observational clinical study. PATIENT SAMPLE: Within this prospective study at a Level I trauma center, we enrolled 38 multiple injured patients with unstable fractures of vertebral column from Level Th1 to L1. Further inclusion criteria consisted of an injury severity score of 16 or more and an intensive care unit (ICU) stay of more than 7 days. The age of included patients was limited from 16 or more to 75 or less years. OUTCOME MEASURES: Hospital stay, stay on ICU, and mortality. METHODS: Twenty-two patients were operated on less than or equal to 72 hours posttrauma, and 16 received late surgery greater than or equal to 72 hours posttrauma. RESULTS: Patients who received early surgery had a significantly higher mortality rate (p<.01) than those who received late surgery. Sixty-seven percent of our patients who had an initial hemoglobin (Hb) less than 10 mg/dL died. Seventy-five percent of those patients who had an Hb less than 10 mg/dL and received a thoracic drain died. CONCLUSIONS: Although some reports indicate advantages for early surgery for thoracic spine trauma in the polytraumatized patient, careful patient selection should be used. Based on the results of this prospective study, early surgery for thoracic spine trauma in patients with concomitant severe thoracic trauma and low initial Hb levels may pose a risk for poor clinical outcomes.

Low-intensity pulsed ultrasound as a useful adjuvant during distraction osteogenesis: a prospective, randomized controlled trial.

BACKGROUND: Low-intensity pulsed ultrasound (LIPUS) was proven to have a positive impact on bone healing in animal and clinical studies. METHODS: In this prospective, randomized controlled trial the effect of LIPUS during distraction osteogenesis was investigated. Thirty-six patients who underwent distraction osteogenesis (>2 cm) were enrolled. Sixteen patients in the treatment group received LIPUS, and 20 patients as control group did not. Ultrasound treatment device was transcutaneously applied at the distraction gap for 20 minutes daily (frequency 1.5 MHz, signal burst with 200 µs, signal repetition frequency 1.0 kHz, intensity 30 mW/cm(2)). Evaluation of patients was performed by standard radiographs every 3 weeks to 4 weeks. RESULTS: Average transport distance was 7.0 cm in the ultrasound group and 6.3 cm in the control group. Mean Paley index for the ultrasound group was 1.09 mo/cm and 1.49 mo/cm for the control group. Mean distraction consolidation index for the ultrasound group was 32.8 d/cm and 44.6 d/cm for the control group. The calculated indices indicated no significant statistical difference between the two groups (p < 0.116) but the fixator gestation period could be decreased for 43.6 days in the treatment group. CONCLUSIONS: Therapeutic application of LIPUS during callus distraction constitutes a useful adjuvant treatment during distraction osteogenesis and has a positive effect on healing time with no negative effects.

Myths and facts of spondylodiscitis: an analysis of 183 cases.

The authors conducted a retrospective study on 183 cases of spondylodiscitis, treated conservatively (44%) or surgically (56%) between November 1991 and June 2006. The male/female ratio was 99/84, and the mean age 62.6 years. The mean follow-up period was 12 years (range 4-19). Interesting from a clinical viewpoint: temperature, white blood cell count, and CRP were sometimes normal, while pain varied from slight to unbearable. The commonest risk factor was diabetes mellitus, and the most frequent pathogen was Staphylococcus aureus. Methicillin resistant Staphylococcus aureus (MRSA) was found in 6 patients, and 3 or 50% of these died, in sharp contrast with the overall mortality rate of 8.7%. A neurological deficit was seen in 43.7% of the patients; complete recovery occurred in 71% of the patients with a Frankel D stage, but in only 15.4 to 222% of those with a stage A, B or C.

Distal tibial fracture post syndesmotic screw removal: an adverse complication.

Fractures of the ankle are common injuries. Some ankle fractures have an associated injury to the syndesmosis, necessitating fixation with one or more screws. Generally, the overall outcome post ankle fracture is good. However, several complications have also been described. The current authors describe a distal tibial fracture following syndesmotic screw removal. A 77-year-old woman was admitted with a bimaleollar right ankle fracture. The patient underwent an emergency operation with open reduction and internal fixation. Six weeks after the surgery, the syndesmotic screw was removed without complication. The patient presented 4 weeks after removal of the screw complaining of persistent swelling and tenderness of the right ankle without a history of trauma. Radiographs showed a non-displaced distal tibial fracture around the site at which the syndesmotic screw was inserted. The distal tibial fracture was treated conservatively with a toe-to-knee cast for 6 weeks. In summary, the authors present a rare case of distal tibial fracture. Surgeons should bear this additional complication in mind.

Direct and indirect loading of the Ilizarov external fixator: the effect on the interfragmentary movements and compressive loads.

The amount of weight bearing and the force transmission to the frame have an important influence on the results of treatment with an Ilizarov external fixator. The frame provides beneficial interfragmentary movements and compressive loads at the fracture site through elastic wires. Mobilisation can be achieved by applying a weight-bearing platform at the distal end of the fixator. The effect on the interfragmentary movements and the compressive loads in indirect and direct loading were analysed in this study using a composite tibia bone model. Displacement transducers were attached to measure the interfragmentary movements and to detect relative movements of the bone fragments and movements between the rings. The compressive loads in the osteotomy were measured with loading cells in the defect zone. The weight-bearing platform had a substantial effect on the biomechanical behaviour of the frame. It led to an indirect force transmission through the fixator with respect to the osteotomy, resulting in lower compressive loads, lower interfragmentary movements and higher mechanical stress on the frame.

Necrotizing fasciitis in patients with spinal cord injury: an analysis of 25 patients.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: The aim of this study was to analyze the correlation between necrotizing fasciitis (NF) and pressure ulcers, as well as the mortality, and complication rate, in patients with spinal cord injury (SCI). SUMMARY OF BACKGROUND DATA: Pressure ulcers represent a challenging problem, especially in immobilized patients. Necrotizing soft tissue infections arising from decubitus ulcers in patients with SCIs have been reported. METHODS: Twenty-five SCI patients with NF treated between April 2000 and December 2009 were included in the study. All patients were analyzed in regard to the number of surgical debridements, length of hospital stay, and laboratory, microbiological, and histological assessments. Information about age, sex, preexisting conditions, anatomical localization, and etiology of the NF were acquired from the patients' medical records. RESULTS: There were 19 paraplegic and 6 tetraplegic patients with a median age of 47 years. In 18 cases, NF developed in the setting of pressure sores. Grade 4 pressure sores were identified in 15 cases and grade 3 pressure sores in 3 cases. The incidence of developing NF is significantly higher in patients with fourth-grade pressure sores than in those with a lower-grade lesion (odds ratio = 2.91; 95% confidence interval, 1.29-6.56). The mean laboratory risk indicator for NF score was 6.6 upon admission. The most common bacteria were streptococci. During the hospital stay, six patients developed sepsis and two died because of septic multiorgan failure. CONCLUSION: Patients with grade 3 and 4 pressure sores had a significantly increased risk of developing NF. The current investigators recommend that close clinical and laboratory monitoring of all patients with grade 3 or 4 pressure sores is appropriate so that any early clinical signs of NF can be recognized and evaluated for early and aggressive treatment.

Isolated subtalar dislocation.

BACKGROUND: Little attention has been devoted to subtalar dislocations without an associated bone injury in the literature to date. The aim of this study was to assess the functional and subjective results of a cohort of patients with this injury. METHODS: A total of ninety-seven patients with a subtalar dislocation were treated at two major university trauma centers from January 1994 to March 2007. Computed tomographic scans indicated a subtalar dislocation without associated bone injury in twenty-three of these patients. Clinical and radiographic examinations were performed on all twenty-three patients at an average of 58.3 months after the completion of treatment. The postoperative clinical examination was supplemented by the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale, and the degree of arthritis was assessed radiographically. RESULTS: The average score on the AOFAS ankle-hindfoot scale score was 82.3 points. Twenty-one patients achieved a good result, and two patients had a satisfactory result. The range of motion of the subtalar joint was an average of 41.3 degrees. No difference between the results of the medial and lateral subtalar dislocations was observed. Only six patients had minor radiographic changes. CONCLUSIONS: The intermediate-term results for a subtalar dislocation without an associated osseous injury are good, and the direction of the dislocation does not appear to make a difference with regard to clinical or radiographic outcome.

Rare complication after VAC-therapy in the treatment of deep sore ulcers in a paraplegic patient.

The VAC-therapy is a safe, easy, and effective therapy for the management of chronic wounds. Known advantages of the VAC technique are the quicker wound healing by stimulating the blood flow, the formation of granulation tissue, angiogenesis, and cell proliferation. The use of negative pressure treatment can decrease the number of dressing changes and length of hospital stay. However, some related complications after and during VAC therapy have been described. We here describe a rare complication during the treatment of severe os ischium sore with VAC therapy, which has not been reported in the literature yet. We report about a 43-year-old paraplegic patient, referred to our clinic from a regional hospital where he had been admitted 2 months earlier, presenting with a necrotizing fasciitis after VAC therapy during the treatment of fourth grade os ischium sore. After operative debridement and long-term antibiotics with Ciprofloxacin soft tissue closure was performed using a myocutaneous tensor fascia lata flap. Temporary stabilization was achieved by a triangle external fixateur attached to the right femur and the pelvis. After 1 week the tapping point of the muscle flap could be covered with local skin mesh-graft from the right calf as a donor site. The patient was mobilized in a wheelchair and was discharged home 3 months after admission. The VAC technique is a safe, easy, and effective means in chronic wound care management. However, the described rare complication should be kept in mind. The clinical management of VAC therapy requires a distinct indication and close clinical monitoring by experienced medical professionals. The use of VAC therapy in fourth grade sores may have deleterious consequences for the patient.

Microvascular response to calcium phosphate bone substitutes: an intravital microscopy analysis.

OBJECTIVES: The purpose was to evaluate inflammatory and microcirculatory reactions after implantation of various calcium phosphate bone substitutes in an in vivo model. METHODS: Calcium phosphate-based bone substitutes were implanted in dorsal skinfold chambers of mice. Intravital fluorescence microscopy was performed to measure inflammatory and microcirculatory reactions based on functional vessel density (FVD), capillary leakage, and relative white blood cell velocity (rWBCV). RESULTS: An increase of FVD was observed in all groups and the capillary leakage grew with a level of significance (p < 0.001). The fraction of rolling and sticking leukocytes (rWBCV) was highest at the beginning of the trial and decreased during the course. CONCLUSIONS: There are differences in microvascular soft tissue reactions between various calcium phosphate bone substitutes, but inflammatory reactions were moderate, and the results revealed no reasons which explain the sporadic failure of the tested substances under clinical conditions.

Exogenous nitric oxide donation causes desensitization of arteriolar relaxing activity in vivo: an intravital analysis in mice.

BACKGROUND: The NO/cGMP pathway plays a crucial role in regulation of tissue perfusion. However, a NO-induced desensitization of cGMP-mediated relaxation has been reported in isolated tissue. To examine whether a similar phenomenon can be detected in vivo, we analyzed relaxations of microvessels in response to repeated applications of NO. MATERIALS AND METHODS: The investigations were performed by means of dynamic intravital fluorescence microscopy in the dorsal skinfold chamber of female balb/mice. First, the microvasculature was maximally preconstricted by the application of the vasoconstrictor 5-hydroxytryptamine. Subsequently, relaxation was induced by applying an NO-donator, the S-nitrosoglutathione, to the contracted vessels. Following buffer exchange, constriction and relaxation were repeated. Drugs were given topically into the chamber, directly onto the skin muscle. The response of arterioles to topical administration of vasoactive drugs was determined as the change of the diameter, and quantified using standard software. RESULTS: The relaxation of arterioles was reduced after repetitive application. The short pretreatment with NO-donor entailed a reduced relaxation of arterioles in response to following application. The absolute change in vessel diameter induced by S-nitrosoglutathione was significantly reduced from 21 µm to 16 µm after the first and the second application, respectively. However, the data also revealed a noticeable reduction of the constricting activity of 5-hydroxytryptamine during the second application, indicating a possible desensitization of the 5-hydroxytryptamine response or a humoral and/or neuronal compensatory mechanisms. CONCLUSIONS: The NO-induced cGMP-mediated relaxation of microvessels was quantified, and the phenomenon of desensitization visualized in vivo by means of dynamic fluorescence microscopy.

Osteogenic differentiation of human mesenchymal stromal cells is promoted by a leukocytes containing fibrin matrix.

PURPOSE: Mesenchymal stem cells (multipotent human mesenchymal stromal cells, MSC) are currently the most promising cell type for regenerative medicine. For a clinical approach, it is necessary to develop and establish methods for expansion, differentiation, and delivery. METHODS: A completely autologous plasma clot containing peripheral blood mononuclear cells (PBMC) was tested for the osteopromotive activity towards expanded human mesenchymal stem cells in vitro. The plasma clot was prepared from anticoagulated blood plasma after addition of isolated leukocytes and calcium chloride. Plasma clots after the gelation were added to subconfluently growing MSC or used in a transwell system. Cell proliferation, the activity of alkaline phosphatase, the release of osteoprotegerin, C-terminal procollagen peptide, as well as osteocalcin, the analysis of matrix mineralization as well as bone nodule formation were analyzed up to 3 weeks. RESULTS: In contrast to plasma clots with no exogenously added leukocytes, the presence of PBMC within the plasma clot significantly promoted osteogenic differentiation of MSC correlated to the time period of incubation. Proliferation of MSC was decreased at maximal mineralization time points. In addition, the osteopromotive activity was identified as soluble factor/factors by transwell assay system. There was a decrease in osteoprotegerin when the cells were cultured in the presence of plasma clots compared to control cell cultures without plasma clots. The osteocalcin expression was continuously higher after culture in the presence of plasma clots and significantly higher after 2- and 3-week after culture in the presence of leukocyte-containing plasma clots compared to 1-week cell culture. Differences in the concentration of the C-terminal procollagen peptide were not measured. CONCLUSIONS: The direct inoculation of an autologous mononuclear cell fraction (which contains leukocytes and MSC), e.g., isolated from a bone marrow aspirate or a different source into an autologous plasma gel, may be a further new strategy for bone fracture therapy.

Additional external hinged fixator after open repositioning and internal fixation of acute elbow instability in non-compliant patients.

This is a retrospective analysis of the clinical and radiological outcome in 11 patients with complex acute posttraumatic elbow instability after dislocation. These patients had also been treated with a hinged external fixator after open reduction, capsular and ligamentous reconstruction and internal fixation, because of an expected diminished compliance, to avoid a secondary dislocation of the internal fixation. Concentric stability and a sufficient range of motion of the elbow joint were achieved in all cases. Non-compliant patients were classified by the surgeon as not compliant or not able or not willing to cooperate post-operatively for various reasons, such as alcoholism, drug abuse, mental disability, cerebral trauma or senile dementia. Non-compliant patients had undergone open reduction and internal fixation of an acute posttraumatic unstable elbow. The addition of a hinged external fixator allows early intensive mobilization, and can protect and improve the clinical outcome after these complex elbow injuries. This evaluation remains, of course, largely subjective and decision making is not easy because in most cases, the patient was not known before surgery. Thus, the only patient exclusion criteria in this study was surgeon classification as "compliant".

The beneficial effects of early stabilization of thoracic spine fractures depend on trauma severity.

BACKGROUND: The timing of stabilization for thoracic spine injuries is discussed controversial. Although early repair of long bone fractures is known to reduce complications, few studies investigate this issue in spine trauma. METHODS: We retrospectively investigated 160 patients (January 2000 to March 2003) with spine fractures from Th1 to L1, which were stabilized. Patients were divided into two groups: early stabilization within 72 hours or later. Other subgroups were analyzed for the relationship of neurologic status, injury severity, and incidence of preoperative lung failure. RESULTS: : Severely injured patients (Injury Severity Score >or=38 pts) with early stabilization had a significantly shorter intensive care unit-stay (14 days [1-34 days] vs. 20 days [1-39 days]; p < 0.05) and overall shorter hospital stay (56 days [9-147 days] vs. 108 days [11-198 days]; p < 0.05). Similar patterns were seen for patients with Frankel A deficits (Frankel Score) and preoperative lung failure. The clinical course of less severe-injured patients was not influenced at all. CONCLUSIONS: Our data provide further evidence that early stabilization of spine injuries is safe. In severely injured patients, it does not impair perioperative lung function and results in a reduced overall intensive care unit and hospital stay.

Treatment of acute and chronic elbow instability with a hinged external fixator after fracture dislocation.

This is a retrospective analysis of the clinical and radiological outcome in 24 patients with acute or chronic posttraumatic elbow instability, who were treated with open reduction, internal fixation and a hinged external fixator. The instability was acute after elbow fracture dislocation in 11 cases; the other 13 had chronic posttraumatic instability of the elbow. Concentric stability and a sufficient range of motion of the elbow joint were achieved in all cases. The addition of a hinged external fixator in noncompliant patients, who underwent open reduction and internal fixation of an acute or chronic posttraumatic unstable elbow, allows early intensive mobilisation and can improve the clinical outcome after these complex elbow injuries.

Epidemiology of traumatic spine fractures.

OBJECTIVES: To illustrate the correlations and effects of age, gender and cause of accident on the type of vertebral fracture and fracture distribution, as well as on the likelihood to sustain an associated injury or neurological deficit. DESIGN: Retrospective analysis of 562 patients with a traumatic fracture of the spine. Each patient was analysed by reviewing the medical records, the initial radiographs and CT-scans. SETTING: Level 1 trauma centre from 01/1996 to 12/2000. RESULTS: The most common cause of accident was a high-energy fall (39%), followed by traffic accidents (26.5%). While fall related fractures were evenly distributed over the whole spine, traffic accidents induced significantly more fractures of the cervical and thoracic spine. Sixty-five percent of all cervical spine fractures and 80% of the multisegmental injuries were accompanied by an associated injury. The highest incidence of associated injuries was observed in patients with multilevel fractures (96.5%). Patients with a concomitant injury were more likely to sustain a spinal cord lesion. Sixty-three (11.2%) patients exhibited a complete motor and sensory deficit, 76 (13.5%) an incomplete and 423 (75.3%) no neurological deficit. The highest number of complete motor and sensory neurological deficits was found in cervical spine fractures (19.7%). The majority of patients, 308 (54.8%), sustained a compression fracture, 95 (16.9%) a distraction fracture, and 104 (18.5%) patients experienced a rotational fracture. CONCLUSIONS: This study demonstrates correlations between the cause of accident, the type of spinal fracture and the fracture distribution. Using the AO classification, the likelihood to sustain either associated and/or spinal cord injuries, is predictable.

Rare anterior shoulder dislocation in a toddler.

Traumatic anterior shoulder dislocation in toddlers and pediatric patients is a very rare injury pattern. The treatment and the recurrence rate are mostly extrapolated from adult and adolescent data. A 2-year-old toddler is presented with a first-time traumatic shoulder dislocation caused by a pull on the abducted arm. The treatment included a gentle closed reduction performing the Milch maneuver and a short-sling immobilization. The 2.5-year-follow-up demonstrated a stable shoulder with free range of motion while still having a Hill-Sachs-lesion. Shoulder dislocation in toddlers maybe addressed less aggressively after closed reduction than in adults due to an unknown recurrence rate.

Which labral lesion can be best reduced with external rotation of the shoulder after a first-time traumatic anterior shoulder dislocation?

INTRODUCTION: Immobilization in external rotation after a first-time traumatic anterior shoulder dislocation has been shown to improve the position of the labroligamentous lesion relative to the glenoid rim. The purpose of the present study was to evaluate the effect of the external rotation position of the shoulder on different types of labroligamentous lesions in patients with first-time traumatic anterior shoulder dislocation by using MRI. PATIENTS AND METHODS: We performed a standardized MRI in internal and external rotation of the shoulder after initial reduction in 34 patients with a first-time traumatic anterior shoulder dislocation. Labroligamentous lesions were classified as Bankart, Perthes, or nonclassifiable. Four distinct grades were used to classify the amount of plastic deformation of the anterior labroligamentous structures. The position of the labrum was defined relative to the tip of the glenoid rim by measuring the dislocation and separation. RESULTS: In all patients, dislocation and separation of the labrum relative to the rim of the glenoid were significantly improved in shoulders in the external rotation position compared to those in the internal rotation position. We observed 15 Bankart, 15 Perthes, and 4 non-classifiable lesions. No HAGL or GLAD lesions were found. Fourteen patients showed a plastic deformation grade I, 16 showed grade II, 3 showed grade III, and 1 showed grade IV. In regression analysis, the odds ratio was 1.100 for the type of lesion and 1.660 for the grade of plastic deformation. Perthes lesions (with an intact anterior scapular periosteum) and grade I plastic deformations showed the best labral reduction on the external rotation MRI. CONCLUSION: Placing the shoulder in external rotation after a first-time traumatic shoulder dislocation, significantly improves the position of the labroligamentous lesion on the glenoid rim. Perthes lesions that showed a low grade of plastic deformation displayed better reduction in external rotation and then compared to Bankart or other lesions that showed a high grade of plastic deformation. In conclusion, immobilization of the shoulder after a first-time traumatic shoulder dislocation is most effective in patients with Perthes lesions that show low grade plastic deformation.

Custom made Ilizarov ring fixator for fracture care in morbidly obese patients.

BACKGROUND: Fracture care in obese patients is becoming an everyday problem because the prevalence of obesity in European countries has tripled since the last 20 years. PATIENTS AND METHOD: With the use of a custom made Ilizarov ring fixator with a ring diameter of 300 to 340 mm, fracture stabilization in three morbidly obese patients was performed. The patients' body mass index (BMI) ranged from 59 to 89. There were one proximal tibia fracture and two pilon fractures. The tibia fracture was stabilized with a 340-mm frame and the pilon fractures were stabilized by primary ankle arthrodesis with 300-mm frames. Primary ankle arthrodesis was performed because polyneuropathy and Charcot arthropathy were present in one patient and in the other patient because time from injury to referral was too long for reconstruction. RESULTS: All patients were able to fully weight bear. Frame removal after fracture correction and consolidation was performed only in the patient with the tibial fracture (patient BMI 89). The other patients died during the treatment because of decompensated comorbidities. CONCLUSION: The Ilizarov technique is a good fixation modality for stabilizing fractures of the lower limb in morbidly obese patients. Associated medical comorbidities are the limitations of successful fracture care.

Colonization of patients and contamination of the patients' environment by MRSA under conditions of single-room isolation.

Meticillin-resistant Staphylococcus aureus (MRSA) are endemic in hospitals worldwide and present a major concern in hospital hygiene. The aim of the present study was to investigate the relationship between patients' MRSA colonization of the body and the frequency of environmental contamination. Twenty-five MRSA-positive hospitalized surgical patients and their environment in isolation rooms were screened on four occasions over a 14-day period. Out of 1099 samples from patients, 330 (30.0%) were MRSA-positive. The median number of MRSA-positive body sites per screening decreased significantly from the 1st (3, range 1-9) to the 14th (2, range 0-9, p=0.011) day of isolation. Contamination was found in 45% of the 100 environmental sampling dates and MRSA was detected in a low proportion of the 1000 environmental surface samples: 105/1000 (10.5%). The number of positive results for each sampling date decreased from the 1st (median 1, range 0-8) to the 14th (median 0, range 0-3, p=0.21) day of isolation. The results show a very strong correlation between the number of MRSA-positive body sites of individual patients and the MRSA contamination of the patient's hospital room (r=0.700, p<0.001). Pulsed-field gel electrophoresis (PFGE) analysis demonstrated a 98% agreement between patient and environmental samples. MRSA colonization of the groin area correlates most strongly with colonization of the body and environment. Seventy-five of 240 (31%) samples taken in rooms of patients with colonization of the groin were MRSA-positive, whereas only 27 of 760 (3.6%) samples taken in rooms of patients without colonization of the groin produced positive results (odds ratio 12.3; 95% confidence interval, 7.7-20). It is concluded that MRSA patients without colonization of the groin have a relatively low risk of environmental spread of MRSA and thus a reduced risk of transmission.

Ultrasound-induced modifications of cytoskeletal components in osteoblast-like SAOS-2 cells.

In clinical and experimental studies an acceleration of fracture healing and increased callus formation induced by low-intensity pulsed ultrasound (LIPUS) has been demonstrated. The exact molecular mechanisms of ultrasound treatment are still unclear. In this study ultrasound transmitted cytoskeletal and growth rate changes of SAOS-2 cells were examined. Osteoblast-like cell lines (SAOS-2) were treated using low-intensity pulsed ultrasound. Cytoskeletal changes were analyzed using rhodamine phalloidine for f-actin staining and indirect immunofluorescence techniques with different monoclonal antibodies against several tubulin modifications. To examine changes of cell number after ultrasound treatment cell counts were done. Significant changes in cytoskeleton structure were detected compared to controls, including an enhancement of stress fiber formation combined with a loss of cell migration after ultrasound application. We further observed that sonication altered the proportion of the more stable microtubules to the more labile microtubule subclass. The labile tyrosinated microtubules appeared highly enhanced, whereas the amount of the more stable acetylated microtubules was remarkably diminished. All these observations were quantified by fluorometric measurements. The centrosomal gamma-tubulin was frequently scattered throughout the cell's cytoplasm, giving rise to additional polyglu-positive microtubular asters, which induced multipolar spindles, leading either to aneuploid mini-or giant cells. Moreover, a significant increase of cell number was noticed in the sonicated group. These experiments demonstrate that ultrasound treatment increases cell number and leads to significant changes of the cytoskeletal structure and composition in vitro.