15 experimental dogs with stainless steel plates and screws fixed in the femur were enrolled into a controlled study to assess histological outcome manifested surrounding the sites of intervention. Plates and screw were firmly attached to the bone. No abnormal reaction was observed macroscopically and microscopically. No inflammatory cells were found after a 45, 90, 135, and 180 days follow-up. The structure and the thickness of the connective membrane in contact with the fixed material had a tendency to become more and more stable. From the day 90, no differences were noted between the group of experimental animals and the control subjects using Chinese SMIC material.
Femoral Fractures ; Bone Screws

OBJECTIVE: To study the self-tapping performance test method of self-tapping bone screws based on the YY/T 1505 standard. METHODS: With reference to the method of YY/T 1505, various factors affecting the self-tapping force test was optimised, and the self-tapping force judgment method was improved. RESULTS: The experimental results showed that the self-tapping force obtained by the improved self-tapping force judgment method has good repeatability and high stability of the experimental data. At the same time, the test results of other influencing factors indicated that the manufacturer should fully consider the test material and the size of the pre-drilled hole. CONCLUSIONS An improved method for judging the self-tapping force is helpful for the repeatability and stability of the test data. This study has certain significance referring to the self-tapping performance test of self-tapping bone screws.
Biomechanical Phenomena ; Bone Screws

OBJECTIVE: Cervical pedicle screw (CPS) placement is very challenging due to high risk of neurovascular complications. We devised a new technique (medial funnel technique) to improve the accuracy and feasibility of CPS placement. METHODS: We reviewed 28 consecutive patients undergoing CPS instrumentation using the medial funnel technique. Their mean age was 51.4 years (range, 30–81 years). Preoperative diagnosis included degenerative disease (n=5), trauma (n=22), and infection (n=1). Screw perforations were graded with the following criteria: grade 0 having no perforation, grade 1 having < 25%, grade 2 having 25%–50% and grade 3 having >50% of screw diameter. Grades 0 and 1 were considered as correct position. The degree of perforation was determined by 2 junior neurosurgeons and 1 senior neurosurgeon. RESULTS: A total of 88 CPSs were inserted. The rate of correct placement was 94.3%; grade 0, 54 screws; grade 1, 29 screws; grade 2, 4 screws; and grade 3, 1 screw. No neurovascular complications or failure of instrumentation occurred. In perforated screws (34 screws), lateral perforations were 4 and medial perforations were 30. CONCLUSION: We performed CPS insertion using medial funnel technique and achieved 94.3% (83 of 88) of correct placement. And it can decrease lateral perforation.
Bone Screws ; Cervical Vertebrae ; Diagnosis ; Female ; Humans ; Neurosurgeons ; Pedicle Screws*

STUDY DESIGN: Biomechanical study. PURPOSE: To determine the effect of density, insertion angle and reinsertion on pull-out strength of pedicle screw in single and two screw-rod configurations. OVERVIEW OF LITERATURE: Pedicle screw pull-out studies have involved single screw construct, whereas two screws and rod constructs are always used in spine fusions. Extrapolation of results using the single screw construct may lead to using expensive implants or increasing the fusion levels specifically in osteoporotic bones. METHODS: Single screw and two screw pull-out strength tests were carried out according to American Society for Testing and Materials F 543-07 on foam models to test the effect of density, insertion angle and reinsertion using poly axial pedicle screws. RESULTS: Bone density was the most significant factor deciding the pull-out strength in both single and two screw constructs. The difference in pull-out strength between single screw and two screw configurations in extremely osteoporotic bone model (80 kg/m3) was 78%, whereas in the normal bone model it was 48%. Axial pull-out value was highest for the single screw configuration; in the two screw configuration the highest pull-out strength was at 10°-15°. There was an 18% reduction in pull-out strength due to reinsertion in single screw configuration. The reinsertion effect was insignificant in the two screw configuration. CONCLUSIONS: A significant difference in response of various factors on holding power of pedicle screw between single and two-screw configurations is evident. The percentage increase in pull-out strength between single and two screw constructs is higher for osteoporotic bone when compared to normal bone. Reinsertion has no significant effect on pull-out strength in the two screw rod configuration.
Bone Density ; Osteoporosis ; Pedicle Screws* ; Spine

STUDY DESIGN: Biomechanical study. PURPOSE: To determine the effect of density, insertion angle and reinsertion on pull-out strength of pedicle screw in single and two screw-rod configurations. OVERVIEW OF LITERATURE: Pedicle screw pull-out studies have involved single screw construct, whereas two screws and rod constructs are always used in spine fusions. Extrapolation of results using the single screw construct may lead to using expensive implants or increasing the fusion levels specifically in osteoporotic bones. METHODS: Single screw and two screw pull-out strength tests were carried out according to American Society for Testing and Materials F 543-07 on foam models to test the effect of density, insertion angle and reinsertion using poly axial pedicle screws. RESULTS: Bone density was the most significant factor deciding the pull-out strength in both single and two screw constructs. The difference in pull-out strength between single screw and two screw configurations in extremely osteoporotic bone model (80 kg/m3) was 78%, whereas in the normal bone model it was 48%. Axial pull-out value was highest for the single screw configuration; in the two screw configuration the highest pull-out strength was at 10°-15°. There was an 18% reduction in pull-out strength due to reinsertion in single screw configuration. The reinsertion effect was insignificant in the two screw configuration. CONCLUSIONS: A significant difference in response of various factors on holding power of pedicle screw between single and two-screw configurations is evident. The percentage increase in pull-out strength between single and two screw constructs is higher for osteoporotic bone when compared to normal bone. Reinsertion has no significant effect on pull-out strength in the two screw rod configuration.
Bone Density ; Osteoporosis ; Pedicle Screws* ; Spine

Thoraco Lumbar spine injury is about 3-5%. But the neurological lesion and sequela was very severe, many of patients became handicap. Early intervention with pedicle screws and plates give us good result for patients with Thoraco Lumbar spine injury
Lumbar Vertebrae ; Bone Screws ; therapeutics ; surgery

Just like other subjects in medicine, orthodontics also uses some vague concepts to describe what are difficult to measure quantitatively. Anchorage control is one of them. With the development of evidence-based medicine, orthodontists pay more and more attention to the accuracy of the clinical evidence. The empirical description of anchorage control is showing inadequacy in modern orthodontics. This essay, based on author's recent series of studies on anchorage control, points out the inaccuracy of maximum anchorage concept, commonly neglected points in quantitative measurement of anchorage loss and the solutions. It also discusses the limitation of maximum anchorage control.
Bone Screws ; Humans ; Orthodontic Anchorage Procedures ; Orthodontics

PURPOSE: To analyze clinical and radiologic results and to identify the relevant factors indicating the cutting out of lag screw for the treatment of peritrocanteric fracture of the femur using a gamma nail. MATERIALS AND METHODS: Eighty-three peritrochanteric fractures, by the Evans classification, were evaluated clinically to assess the walking capacity. Radiologically bone union, reduction status, sliding, position of the lag screw, bone density, displacement, and tip-apex index (TAD) were evaluated. The relationship between the cutting out of lag screw and the relevant factors such as age, osteoporosis, sliding of lag screw, TAD, fracture stability were analyzed. RESULTS: Time to union averaged 14.1 weeks in stable fractures and 21.5 weeks in unstable fractures. Acceptable reduction was available in 75 (91.5%) cases. Superior-anterior positioning of the lag screw was only found in 3 (3.4%) cases. Average sliding of the lag screw was 3.9 mm. Mean proximal protrusion of the nail was 4.8 mm, and mean TAD was 25.29 mm. Cutting-out was occurred in 9 (10.8%) cases. Sliding (>10 mm) and TAD (>25 mm) were related significantly to cutting-out (p<0.05). Complications occurred in 26 cases (31.2%), however, there was only one case of cutting-out in reverse obliquity fracture accompanying subtrochanteric component. CONCLUSION: Complications for the treatment of peritrochanteric fracture using a gamma nail were not insignificant. To prevent cutting out of lag screw, care must be taken to keep the TAD below 25 mm.
Bone Screws ; Classification ; Femur* ; Osteoporosis ; Walking

Kuntscher introduced the interlocking nail as the name of Detensionsnagel at 1968. Klemm, Kaessman, Hempel used it clinically through transverse hole. Authors tried to make the sagittal hole at the dorsum of the Kiintscher nail, which was interlocked- from the slot to the hole by bone screw. The direction of the sagittal hole crossed right angle to the transverse hole. Analysis of 35 cases conducted following conclusion. 1. Transfixing the screw at the sagittal hole of the nail can be done easily when transfixing through the transverse hole is difficult. 2. There was no difference in stability between transverse hole and sagittal hole transfixation. Lateral movement of the nail was disappeared after transfixation of the screw at the sagittal hole. Interlocking system is very similar to Harrington distraction rod system. 3. One case of nail breakage had occured at the transverse hole. Nail breakage easily occurs if the hole is situated near the fracture site. For prevent nail breakage larger nail insertion is desirable. (More than 14mm in femur and more than 12mm in tibia.) 5. Indication of the I-M nailing is widened by screw interlocking: from the subtrochanteric fracture to the supracondylar fracture of the femur. It is also useful in arthrodesis of the knee joint. 6. Addition of the Interlocking in ordinary I-M nailing patient could walk 3 to 10 days after operation and radiologic union achieved 12 to 20 week after opeation.
Arthrodesis ; Bone Screws ; Femur ; Humans ; Knee Joint

Secondary soft tissue injuries can occur from the pressure of the displaced fragment of posterior calcaneal tuberosity in calcaneal tongue-type fractures and calcaneal tuberosity avulsion fractures. The soft tissue injury can be prevented by immediate reduction of the displaced fragments. Various techniques can be used to fix the fracture fragments, but the stability of fixation and minimal invasiveness to soft tissue should be considered. This paper reports the successful outcomes of patients with soft tissue compromises in calcaneal tongue-type fractures and calcaneal tuberosity avulsion fractures. The fixation technique of a large cannulated screw and simple cerclage wiring is believed to be a useful surgical option for the treatment of secondary soft tissue compromised calcaneal fractures.
Bone Screws ; Bone Wires ; Calcaneus* ; Humans ; Soft Tissue Injuries