Forces required to dynamize sliding screws in gamma nail and selfdynamizable internal fixator.

BACKGROUND: Single limb support phase of the gait-cycle in patients who are treated for a pertrochanteric fracture is characterized by transversal loads acting on the lag screw, tending to block its dynamization. If the simultaneous axial force overcomes transversal loads of the sliding screw, the dynamization can still occur. METHODS: Biomechanical investigation was performed for three types of dynamic implants: Gamma Nail, and two types of Selfdynamizable Internal Fixators (SIF) - SIF-7 (containing two 7 mm non-cannulated sliding screws), and SIF-10 (containing one 10 mm cannulated sliding screw). Contact surface between the stem and the sliding screws is larger in SIF implants than in Gamma Nail, as the stem of Gamma Nail is hollow. A special testing device was designed for this study to provide simultaneous application of a controlled sliding screws bending moment and a controlled transversal load on sliding screws (Qt) without using of weights. Using each of the implants, axial forces required to initiate sliding screws dynamization (Qa) were applied and measured using a tensile testing machine, for several values of sliding screws bending moment. Standard least-squares method was used to present the results through the linear regression model. RESULTS: Positive correlation between Qt and Qa was confirmed (p < 0.05). While performing higher bending moments in all the tested implants, Qa was higher than it could be provided by the body weight. It was the highest in Gamma Nail, and the lowest in SIF-10. CONCLUSIONS: A larger contact surface between a sliding screw and stem results in lower forces required to initiate dynamization of a sliding screw. Patients treated for a pertrochanteric fracture by a sliding screw internal fixation who have longer femoral neck or higher body weight could have different programme of early postoperative rehabilitation than lighter patients or patients with shorter femoral neck.

The Selection of Main Surgical Work Factors in Operating Rooms.

The main component of error minimization in operating rooms (ORs) is to maintain high reliability of surgical teams. The analysis of adverse events in the OR reveals deficiencies in cognitive and interpersonal skills as the main factors influencing surgeons' errors. Therefore, research of these additional factors is necessary, besides factors related to surgeons' clinical knowledge and technical skills. In this paper, the key factors for evaluating activities in surgical operating rooms are identified. Fuzzy analytic hierarchy process is used for identification of key factors. Fifteen key factors are identified for evaluating activities in surgical operating rooms to improve the efficiency of surgical operations. For each group of activities (surgical "capabilities," operating room characteristics, and non-technical skills), five factors are identified. As the most important, the following factors are obtained: communication, indoor environment standardization, and tool handle design. The aim of the analysis of these key factors is surgeons' work capability enhancement, rational design of operating rooms, and advancement of operators' cognitive and interpersonal skills.

Influence of coronavirus disease 2019 pandemic state of emergency in orthopaedic fracture surgical treatment.

PURPOSE: After the appearance of first COVID-19 cases in Serbia, state of emergency was declared on 15 March 2020 and lasted for 54 days. The aim of this report is to compare orthopaedic fracture frequencies in this period, when the walk was limited at the home mostly, with those during the same part in the previous year with regular state, thus to examine staying at home as a factor influencing the frequency of different fracture types. METHODS: There were 86 patients during the state of emergency in year 2020 and 106 patients during the same part of year 2019 with a regular state, having orthopaedic trauma surgery. Number of fractures, gender distribution, and age of patients have been compared between these periods. RESULTS: Total number of fractures decreased for about 19% during the state of emergency. There was nonsignificant difference in fracture frequency for all skeletal areas (p > 0.05), except for distal femoral fractures which occurred more often during the state of emergency (p < 0.05). Female ratio was higher during state of emergency than in regular state for femoral neck fractures. CONCLUSION: Restricted going outside the home for 54 days has the influence in total number of fractures and gender distribution in femoral neck fractures. The method of external fixation used could be assumed as a reducing factor of intraoperative virus pandemic propagation among medical staff.

Treatment of stable and unstable intertrochanteric fractures with selfdynamisable internal fixator (concept of double dynamisation).

UNLABELLED: BACGROUND/AIM. Intertrochanteric fractures of the femur are the third most common fractures among all bone fractures. Today in everyday orthopedic practice a number of different methods of treatment of trochanteric fractures of the femur are applied. Despite the improvement in the development of new implants, the percentage of serious complications of the treatment of these fractures remains very high, varying from 10% to 20%. One of the most serious complications of internal fixation of intertrochanteric fractures is nonunion of fractures due to the lack of additional axial dynamisation of implants. The aim of this study was to determine the efficacy of double dynamisation in stable and unstable intertrochanteric fractures treatment using the self dynamisable internal fixator. METHODS: During the period from 2000 to 2009 we analyzed the use of selfdynamisable internal fixator (SIF implant) in the treatment of 247 patients with stable and unstable intertrochanteric fractures. Fracture types were classified according to the AO Fracture Classification/Orthopaedic Trauma Association Scheme. Salvati and Wilson scoring systems were used for functional assessment considering pain, walking ability and hip movements of operated patients. RESULTS: Of the total number of treated patients, 134 were males and 113 females, aged 19 to 90 (average 49.6) years. More than a half of the patients were older than 50 years. Monitoring of the patients after the operation was carried out clinically and radiographically for a period of three to six months in all the patients, whereas a 2-year follow-up was conducted in 176 (71.2%) patients. The average duration of surgery was 47 min, the average blood loss 145 mL, and the average fluoroscopy time was 16 sec (8-97 sec). The average time for union was 3.7 months (3-6.6 months). Double dynamisation (dynamisation along the neck and shaft of the femur) was observed in 85 (34.4%) patients, and was on average 4.3 mm (1.5-8 mm). All fractures managed with dynamisation implants healed completely within no later than six months after the surgery. In 17 cases there was a cut-out phenomenon of implant, while in seven cases there was mechanical implant failure. Complications were detected within 3 to 6 weeks after surgery, and treated by the method of intramedullary fixation. During the study, there were no cases of infection and thromboembolic complications detected. CONCLUSION: The concept of double dynamisation improves the fracture healing in the stable and unstable intertrochangeric fractures using the selfdynamisable internal fixator. This biological method of fixation provides healing of intertrochanteric fracture in the optimum period of time, significantly reducing the risk for mechanical failure.

Dilemmas in the treatment of tibial diaphyseal fractures.

INTRODUCTION: Tibial fractures accompanied by radius fractures at typical sites are the most common type of fractures. OBJECTIVE: The study is aimed at using the examined sample to make an efficient and economically acceptable choice in the treatment of tibial diaphyseal fractures. MATERIAL AND METHODS: The series comprises a retrospective and prospective study of the treatment of 131 fresh tibial fractures: 31 in women (23.66%) and 100 in men (76.34%) of the average age of 37.89. Nineteen patients (14.50%) were treated conservatively and 112 (85.50%) surgically: 22 (16.79%) with anti-rotation intramedullary nails, 74 (56.49%) with Mitkovic external fixator type M20, and 16 (12.21%) with locking compression plate. General anaesthesia was used in 46 patients (35.11%), while spinal anaesthesia was used in 85 of them (64.89%). RESULTS: According to the Karlstrom-Olerud scoring system, the treatment results were as follows: for the 22 tibiae treated with anti-rotation intramedullary nails: in 15 (68.18%) the results were excellent, in 3 (13.64%) they were good and in 4 (18.18%) they were poor. As for the results for the 74 tibiae treated with Mitkovic external fixator type M20, they were as follows: in 62 (83.78%) excellent, in 9 (12.16%) good, and in 3 (4.05%) they were poor. The results for the 16 patients treated with locking compression plate were excellent in 10 (62.50%), good in 2 (12.50%) and poor in 4 patients (25.00%). The treatment results for the 19 tibiae treated with plaster cast were excellent in 12 patients (63.16%), good in 2 (10.53%) and poor in 5 (26.32%). The definite results for the 131 fractured tibiae treated with the aforementioned techniques were as follows: excellent in 99 (75.57%), good in 17 (12.98%) and poor in 15 patients (11.45%). DISCUSSION: There is a variety of controversial positions concerning the treatment of the tibial diaphysis. CONCLUSION: On the basis of the results of surgical treatment for the given series, the number of surgical interventions, the price of osteosynthetic material, my preferences in treating tibial diaphyseal fractures would be as follows: Mitkovic external fixator type M20, anti-rotation intramedullary nails and locking compression plate. Conservative treatment is indicated when the X-ray examination confirms that the fragments have a position acceptable for conservative treatment with plaster cast.

[Minimally invasive treatment of bilateral femoral shaft fractures in polytrauma patient using selfdinamisibile internal fixator. A case report].

Proper timing and surgical method in management of femur fractures in polytrauma patients can greatly reduce the mortality, morbidity and disability. The aim of this paper is to present the treatment of bilateral femoral fractures in polytrauma patient with dominant chest trauma by selfdynamisable internal fixator Mitkovic (SIF) as a definitive method of fractures treatment. A 23 years old female was injured in a traffic accident. After resuscitation and treatment of the dominant chest injuries, surgical treatment of bilateral femur fractures performed on the fourth day after the injury. Length of surgery was 65 minutes. There was not blood substitution during the intervention and blood loss through the operative wounds drainage. There was no worsening of the pulmonary function after orthopaedic surgery. The patient discharged from hospital postoperative day ten. Postoperative follow-up was 9 months. The fractures healed with an excellent functional result. Application of selfdynamisable internal fixator (SIF) with minimally invasive technique for the treatment of bilateral femoral fractures in polytrauma patients is a good operative method because poses minimally additional operative trauma and provides excellent biomechanical conditions for fracture healing.

[Results of the application of a new method of internal fixation of femoral neck fractures--self-tapping antirotation cannulated screws (SAF)].

INTRODUCTION: Femoral neck fractures are one of the most common fractures primarily the elderly, coupled with a high degree of morbidity and mortality. The treatment is applied a number of methods of internal fixation (multiple cannulated screws available, DHS system, cefalomedullary). At the Department of Orthopedics and Traumatology of Nis developed a new method of fixation of femoral neck fracture, which allows stable fixation of dislocated and nondislocated femoral neck fracture. Self-tapping antirotation fixation (SAF) using two cannulated screws to initial compression fractures intraoperative and postoperative dynamic linear compression of the fracture with early full support to the patient. MATERIAL AND METHODS: In the period between 2008 to 2012, 53 patients treated for femoral neck fracture in the Clinic for orthopedic and traumatology, Clinical center in Nis, Serbia, by SAF (the self-tapping cannulated screws antirotation; ORTOKON doo Nis). All patients were followed up after surgery in a minimum period of 13 weeks (13-106 weeks). The outcome was evaluated on the basis of clinical and radiological signs of fracture healing and the Harris hip score of functional recovery of the patient. RESULTS: Of the total number of patients (53) treated with this method of fixation, 31 of them were females and 22 males, mean age 52.7 years (28-75 years). The average time of surgery was 36.4 minutes (19-70 minutes). During the postoperative follow-up of all patients (53) operated by this method, six patients were lost in the further postoperative monitoring, so that 47 patients remained for final evaluation. The total incidence of nonunion of femoral neck fracture after surgery this method was 6.4% (three patients). Shortening of the femoral neck after fixation by this method was recorded in 27 cases, and what amounted to an average of 2.8 mm (1, 2 mm in nondislocated to 4.55 with dislocated fracture) and did not affect the functional outcome. During radiographic follow-up was not detected fracture implants. CONCLUSION: Self-tapping screws cannulated antirotation (SAF method) represent a reliable method of fixation of dislocated and nondislocated femoral neck fracture. The main prerequisite for the proper healing of femoral neck fractures with this method is that anatomical fracture reduction is achieved by a closed or open method. This way of fixation allows the early full weight bearing patient operated limb and faster postoperative functional recovery of the fracture healing in optimal time.

[Dynamic forces of Mitkovic self-dinamysible trochanteric Internal fixators (SIF)].

Dynamic trochanteric fractures implants allow fracture fragments to be compressed. Dynamisation can be realized if the axial pin force overcome friction force between pin and body of the implant. Examination of sliding iniciation forces in Mitkovic Selfdinamysible Trochanteric Internal Fixator (SIF). SIF was attached for angle block in the position with vertical orientation of pins. The transversal load of 5 kg was connected to pins by a rope. A dynamometer was used to measure force during the movement of angle block in up direction. Regression coefficients were a1 = 4,052 i b1 = 0,623 for SIF with 2 sliding screws with diameter of 7mm and a2 = 4,534 i b2 = 0,422 for SIF with 1 screw with diameter of 10 mm. Coefficients of determination were: r12 = 0,470 and r22 = 0,123. Sliding of SIF pins can be achieved for each analysed body weight of patient (50-130 kg). Early bearing of operated leg is significant for sliding initiation of SIF sliding screws.

Patellofemoral disorders and instability.

Originally the main idea was to obtain a stable patella, i.e., to stabilize the "slipping patella". In the past many conditions like patella alta, ligamentous laxity, PF bone hypoplasia, weakness of the quadriceps muscle, genu valgum or genu recurvatum were thought to predispose to patellar instability. For a long period muscle exercises were instituted to strengthen the weak m.vastus medialis and to make vastus lateralis stronger. This pulls the patella laterally, especially during running or jumping, when lateral luxation of the patella occurs. Muscle imbalance as well as anatomical abnormalities are the basis both for patellar instabilities and reasonable surgical procedures were: proximal extensor mechanism realignment, proximal capsular reefing, patellar tendon splitting and its medial transfer. On the other hand bone procedures on the hypoplastic lateral femoral condyle were also performed by Albee, as well as tibial tubercle transfer and trochleoplasty by deepening of the trochlea (Dejour). An understanding of the pathoanatomic basis is the corner stone for

[Deformities correction of metacarpal and phalangeal bones by the use of Mitkovic minifixator].

It is shown results of the application of the Mitkovic external mini fixator in different indication of fractures and deformities correction of metacarpals and phalanges. Series of 14 applications in 11 patients have been introduced in this study: 3 lenthenings of metacarpals, 7 correction mallunion of metacarpals and phalanges and 4 gradual correction of the posttraumatic stiffness of the joints of the 2nd to 5th fingers. Average age was 23 years (15 to 54) and follow up was 6 months to 5 years. This external fixator is versatile. Operations have been minimally invasive: corticotomyes, and haemicorticotomies were performed through 10-15 mm long incision. There were no complications in regard of delay union or nonunion, pin track or other infection, joint stiffness nor damage of neurovascular elements. It can be concluded that this External Mini-fixator is suitable for routine solving of different deformaties of hand bones.

[Fractures of the upper part of the femur treated with Mitkovic selfdynamisable internal fixator (SIF)].

UNLABELLED: Complex transtrochanteric and subtrochanteric fractures need dynamisation in two axis: in neck axis and in the long axis of the femur. In this study is present one new concept of the surgical treatment of the fractures of proximal femur using new double dynamic selfdynamisable internal fixator (SIF). Dynamisation along the femoral neck axis is available immediately after the fixation, while dynamisation in the long axis of the femur is activated spontaneously 4-6 weeks after the fixation. It is shown seris of 30 consecutive fractures of the upper femur. The average operative time was 42 minutes and average blood loss was 70 (seventy) milliliters. All fractures healed within an average period of sixteen weeks (ranging from 12 to 24 weeks). There were no serious complications. CONCLUSION: SIF is one effective minimally invasive method for the treatment of complex trochanteric and subtrochanteric femoral fractures.

[Influence of pins configuration to balance of general transversal stability in long bone fractures external fixation].

Biomechanical features of long bones indicate that external fixation of long bone fractures have to be balanced according to general transversal stability as more as possible. The aim of this work was to investigate the influence of orientation pins to the general transversal stability of external fixation of fractures of long bones. In this study we have used the model of fractured long bone made of wood which was treated by Mitkovic external fixator with 4 pins, in 3 different situations: (1) all pins are in one axial plane, (2) each 2 pins are in 2 axial planes with angle distances of 60 degrees, (3) each 2 pins are in 2 axial planes wich are normal to each other. Means of relations of measured movements of long bone model fragments during the use of perpendicular force from 2 directions, normal to each other, after grouping of results in 3 grous: 0.17, 0.46 and 0.72. Statistical analyses showed that the differences between each of 3 grous were significant (p < 0.05). It can be concluded that it is better if pins are oriented in different axial planes, with pretension that both planes are normal to each other, during external fixation of long bone fractures.