Biomechanical comparison of fracture site stabilities of femur nails after fracture site resorption.

Instability increases after fracture site resorption. This study aimed to compare the fracture site stabilities of different femoral nails after fracture site resorption. Thirty composite femurs were divided into three groups of 10 interlocking nails. Using axial compression-distraction machines and a custom-made torsion device, the fracture site rotational and axial stabilities after 1 mm fracture site resorption were determined. Between 6 Nm external and 6 Nm internal rotation torques, the means of the maximum fracture site rotation arc of motion were 5.94 mm for compression nails, 5.9 mm for interlocking nails and 3.5 mm for CAROT nails. Between 2300 N compression and 150 N distraction forces, the means of the fracture site axial motion were 3.15 mm for interlocking nails, 1.26 mm for compression nails and 1.26 mm for CAROT nails. CAROT nails are superior to compression and interlocking nails in fracture site rotational and axial stabilities after 1 mm fracture site resorption.

The best location for proximal locking screw for femur interlocking nailing: A biomechanical study.

BACKGROUND: Proximal locking screw deformation and screw fracture is a frequently seen problem for femur interlocking nailing that affects fracture healing. We realized that there is lack of literature for the right level for the proximal locking screw. We investigated the difference of locking screw bending resistance between the application of screws on different proximal femoral levels. MATERIALS AND METHODS: We used a total of 80 proximal locking screws for eight groups, 10 screws for each group. Three-point bending tests were performed on four types of screws in two different trochanteric levels (the lesser trochanter and 20 mm proximal). We determined the yield points at three-point bending tests that a permanent deformation started in the locking screws using an axial compression testing machine. RESULTS: The mean yield point value of 5 mm threaded locking screws applied 20 mm proximal of lesser trochanter was 1022 ± 49 (range 986-1057) (mean ± standard deviation, 95% confidence interval). On the other hand, the mean yield point value of the same type of locking screws applied on the lesser trochanteric level was 2089 ± 249 (range 1911-2268). Which means 103% increase of screw resistance between two levels (P = 0.000). In all screw groups, on the lesser trochanter line we determined 98-174% higher than the yield point values of the same type of locking screws in comparison with 20 mm proximal to the lesser trochanter (P = 0.000). CONCLUSION: According to our findings, there is twice as much difference in locking screw bending resistance between these two application levels. To avoid proximal locking screw deformation, locking screws should be placed in the level of the lesser trochanter in nailing of 1/3 middle and distal femur fractures.

The functional results of tibial shaft fractures treated with intramedullary nail compressed by proximal tube.

Nailing of tibial shaft fractures is considered the gold standard surgical method by many surgeons. The aim of this retrospective study was to investigate and compare the clinical outcome of tibial shaft fractures treated with intramedullary nails compressed by proximal tube and conventional intramedullary interlocking nails. Fifty-seven patients with tibial shaft fractures, treated with intramedullary nails compressed by proximal tube (n = 32) and the conventional interlocking nails (n = 25), were reviewed. All fractures except for one were united without any additional surgical intervention in the proximal compression tube nail group, whereas in the conventional interlocking nail group, six patients needed dynamization surgery (p = 0.005) and three cases of nonunion were recorded. In the proximal compression tube nail group, faster union occurred in 20 ± 2 (16-24) weeks (mean ± SD; range) without failure of locking screws and proximal nail migration, whereas in the conventional interlocking nail group, union occurred in 22 ± 2.5 (17-27) weeks (p = 0.001) with two failures of locking screws and two proximal nail migration. The proximal compression tube nail system is safer than the conventional nailing methods for the treatment for transverse and oblique tibial shaft fractures with a less rate of nonunion, proximal locking screw failure and proximal nail migration.

A new femoral nail with single distal locking screw for maximum interfragment rotational stability.

OBJECTIVE: One of the problems for interlocking nailing of the femur is interfragment rotation motion, affecting fracture healing. The nails with single distal locking screw are advantageous for decreasing operation time and radiation exposure. We investigated which single distal screw nail is the best for interfragment rotational stability. METHODS: We used a total of 30 composite femurs, ten for each group. We determined interfragment rotational displacement of composite femurs with three types of single distal screw nails (10 interlocking nails, 10 compression nails and 10 Mehmet anti-rotation nails compressed by tube) at 6-Nm external- 6 Nm internal and 10 Nm extern- 6 Nm internal torques, which imitating respectively the level walking and descending stairs, using an axial distraction testing machine and a custom designed rotation apparatus. RESULTS: Between 10 Nm external and 6 Nm internal torques with single distal locking screw, the interfragment rotational displacement in the Mehmet nail compressed by the 8 Nm torque wrench was mean 1.14 mm and 540% less than mean 7.31 mm in interlocking nails and 400% less than 5.72 mm in compression nails compressed by the 2.5 Nm torque wrench. CONCLUSION: The single distal screw Mehmet nail is superior than other single (or even some double) distal screw nails for maximum rotational stability, with no interfragment distraction gap, no superior nail migration, decreased operation time, and less radiation exposure in axially stable transverse and short oblique femur fractures in daily activities like stair descending or level walking.

Unilateral lymphedema as first presentation of sarcoidosis / Linfedema unilateral como primera presentación de sarcoidosis

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Reliability of threaded locking screws.

OBJECTIVE: A frequent problem for interlocking nailing that affects the treatment of the fracture is locking screw deformation. The aim of this study is to determine whether bending resistance is different between high, low, and unthreaded locking screws of interlocking femoral nails. METHODS: Ninety screws were used in this experimental study, with 10 screws used in each of 9 groups. Three-point bending tests were performed on 6 groups of 5 mm screws (titanium, stainless steel, crossed with unthreaded, low threaded, and high threaded) and the same 3 thread types of 5.5 mm stainless steel screws in a 30-mm inner diameter steel tube, imitating the level of the lesser trochanter. An axial compressor was used to determine the yield points for permanent deformation in the locking screws by way of 3-point bending tests. RESULTS: The mean yield point value of the 3-point bending tests of 5-mm low threaded stainless steel locking screws was 2071 N, 53% less than that of unthreaded screws (3169 N). The mean yield point value of 5-mm high threaded stainless steel locking screws was 556 N, 272% less than that of low threaded screws (2071 N). CONCLUSION: To avoid locking screw deformation, high threaded screws must not be used as locking screws. In cases of unreliable patients, 5-mm low threaded screws should not be used in the nailing of comminuted or oblique femur shaft fractures. All 5-mm unthreaded screws and 5.5-mm low threaded stainless steel screws can be used safely in full weight-bearing conditions of unreliable patients.

Biomechanical comparision of femoral intramedullary nails for interfragmentary rotational stability.

OBJECTIVES: This study aims to investigate which intramedullary nail is biomechanically better for establishing interfragmentary rotational stability. MATERIALS AND METHODS: Thirty composite femurs were utilized in this study. We analyzed interfragmentary rotational arc displacements between 10 Nm external-6 Nm internal torques and 6 Nm external-6 Nm internal torques which imitate rotation torques while walking on a flat surface and descending stairs by administering 10 interlocking nails, 10 compression nails, and 10 Mehmet anti-rotation nails with tube compression. RESULTS: Maximum interfragmentary rotation arc displacement between 10 Nm external rotation and 6 Nm internal rotation torques was mean 1.64 mm in the Mehmet nail compressed by 7 Nm torque wrench. This value was lower by 309% (6.72 mm) from interlocking nail (p=0.000), 201% (5.42 mm) from compression nail compressed by 2.5 Nm torque wrench (p=0.000), and 26% (1.92 mm) from compression nail compressed by 7 Nm torque wrench (p>0.05). CONCLUSION: In axially stable transvers and short oblique femur fractures, Mehmet nail is superior to other intramedullary nails with limited movement between locking screw and hole, more interfragmentary compression without locking screw deformation, and no proximal nail migration.

Biomechanical comparison of three-point bending resistance of titanium and stainless steel locking screws in intramedullary nails.

OBJECTIVES: This study aims to investigate whether there is any significant difference in bending resistance between titanium and stainless steel locking screws of femur nails and to review deformation of locking screws which is a common problem in interlocking nailing. MATERIALS AND METHODS: In this study, a total of 60 pieces of 5 mm major diameter titanium and stainless steel locking screws were used as six groups in three different thread depth structures (high threaded, low threaded, and unthreaded). Three-point bending tests were conducted on steel screws placed inside stainless steel tube with 30 mm inner diameter, which imitated the level of lesser trochanter. We used an axial compression testing machine in order to determine the yield points that permanent deformation occurred in the locking screws. RESULTS: For low threaded locking screws, which are the most frequently used thread type for locking screws, the mean bending yield points were 1413 N on the titanium screws and this level was below 1922 N (2.8 BW) of level walking loading on femur for 70 kg person. On low threaded stainless screws, bending resistance was 2071 N, which was above the value of 1922 N. For high threaded locking screws, the mean bending yield points were 874 N on the titanium screws and 556 N on stainless screws. CONCLUSION: In comminuted femur shaft fractures (in full load bearing conditions), using stainless steel locking screws is better instead of titanium screws to avoid locking screw deformation since low threaded stainless steel screws were 46.5% more resistant to bending deformation than titanium ones. Stainless steel or titanium high threaded locking screws may only be carefully used in non-comminuted fractures.

A new compression design that increases proximal locking screw bending resistance in femur compression nails.

The aim is to present our new method of compression, a compression tube instead of conventional compression screw and to investigate the difference of proximal locking screw bending resistance between compression screw application (6 mm wide contact) and compression tube (two contact points with 13 mm gap) application. We formed six groups each consisting of 10 proximal locking screws. On metal cylinder representing lesser trochanter level, we performed 3-point bending tests with compression screw and with compression tube. We determined the yield points of the screws in 3-point bending tests using an axial compression testing machine. We determined the yield point of 5 mm screws as 1963±53 N (mean±SD) with compression screw, and as 2929±140 N with compression tubes. We found 51% more locking screw bending resistance with compression tube than with compression screw (p=0,000). Therefore compression tubes instead of compression screw must be preferred at femur compression nails.

Demographic, clinical, and laboratory features of Turkish patients with late onset ankylosing spondylitis.

Ankylosing spondylitis (AS) is a chronic inflammatory disease, which typically begins in early decades of life with primarily axial joints involvement. This disease rarely affects patients older than 50 years of age. The aim of this study was to compare and evaluate the demographic, clinical, and laboratory features of late onset and early onset AS patients who were followed up in a single rheumatology center. A total of 339 patients who have been diagnosed with AS according to modified New York criteria were included in the study. The patients whose initial symptoms were observed after 50 years of age were accepted as late onset AS. Out of 339 patients, 27 (7.9%) were diagnosed as late onset AS and 312 (92.3%) patients were evaluated as early onset AS. Of 27 late onset patients, 10 were male and 17 were female. Delay in the diagnosis was 5.8 years for early onset AS, while it was 3.8 years for late onset AS (p = 0.001). Higher levels of acute phase reactants and more methotrexate (MTX) use were detected in early onset AS patients compared to late onset AS (p = 0.001, p = 0.007, respectively). Statistically, there was no difference between these two groups, with regard to disease clinical activity indexes, anthropometric measurement parameters, uveitis and peripheral joint involvement. In this study, we showed that early and late onset AS patients may present with different clinical, genetic, and laboratory features. Late onset AS patients are characterized with lower human leukocyte antigen-B27 sequence, less inflammatory sign, delayed diagnosis, and less MTX and anti-tumor necrosis factor alpha drug usage.

Traumatic distal ulnar artery thrombosis.

This paper is about a posttraumatic distal ulnar artery thrombosis case that has occurred after a single blunt trauma. The ulnar artery thrombosis because of chronic trauma is a frequent condition (hypothenar hammer syndrome) but an ulnar artery thrombosis because of a single direct blunt trauma is rare. Our patient who has been affected by a single blunt trauma to his hand and developed ulnar artery thrombosis has been treated by resection of the thrombosed ulnar artery segment. This report shows that a single blunt trauma can cause distal ulnar artery thrombosis in the hand and it can be treated merely by thrombosed segment resection in suitable cases.