Multiple screws versus sliding hip screws in femoral neck fractures: A protocol of cohort study.

BACKGROUND: There has been a paucity of cohort trials directly comparing multiple cannulated screws (MCS) and sliding hip screws (SHS) in femoral neck fractures at any level. Thus, a well-conducted clinical trial with an adequate sample size is urgently needed. We undertake a retrospective study to compare outcomes in patients who undertake MCS or SHS fixation for femoral neck fractures. METHODS: A retrospective review of femoral neck fractures performed with SHS or MCS between February 2016 and June 2018 was conducted with Institutional Review Board approval in the First Affiliated Hospital of Dali University of Orthopedic Trauma. All cases were performed by a single surgeon. Of these, we included 180 patients (90 hips) that were performed surgery in treatment of femoral neck fractures. All patients received the same standardized postoperative multimodal pain protocol and the same postoperative rehabilitation program. The primary endpoint was Harris Hip Score. Secondary outcome measures include operation time, length of hospital stay, incision length, patient satisfaction, and postoperative complications. Multivariate linear and regression analyses was used to identify independent predictors of outcome. A P-value of <.05 was defined as statistical significance. RESULTS: We hypothesize that both treatments provide comparable outcomes. TRIAL REGISTRATION: This study protocol was registered in Research Registry (researchregistry5638).

Comparison of dynamic hip screw and antirotation screw with cannulated screw in the treatment of transcervical collum femoris fractures.

OBJECTIVES: This study aims to compare the results of internal fixation with dynamic hip screw (DHS)/antirotation screw and conventional cannulated screw (CS) for femoral neck fracture. PATIENTS AND METHODS: This retrospective study included a total of 78 patients (57 males, 21 females) with collum femoris fractures treated with internal fixation between January 2015 and January 2019. Group 1 comprised 41 patients with a mean age of 45.7 years (range, 19 to 62 years) treated with DHSs/antirotation screws, while group 2 comprised 37 patients with a mean age of 41.9 years (range, 17 to 75 years) treated with CSs. The patients were evaluated for union, avascular necrosis (AVN), femoral neck shortness, operation time, duration of fluoroscopy exposure, and functional outcomes. RESULTS: Age, gender, and Garden classification stages were similar in both groups. No significant difference was found between the groups in respect of AVN and non-union rates. The non-union rate was 12.2% in group 1 and 21.6% in group 2 (p>0.05). The duration of fluoroscopy exposure was statistically significantly higher in group 2 (p=0.001) and the operation time was statistically significantly longer in group 1 (p=0.001). In group 2, femoral neck shortness stature was significantly higher (p=0.007). At the final follow-up examination, the Harris hip score was statistically significantly higher in group 1 (p=0.04). CONCLUSION: Dynamic hip screw/antirotation screw was a more relevant treatment method for transcervical femoral neck fractures compared to CS with more favorable functional outcomes and less fluoroscopy exposure.

[Comparison of bioabsorbable screw and metallic screw for Maisonneuve fracture].

OBJECTIVE: To compare the clinical and radiographic outcomes of bioabsorbable screw and metallic screw for Maisonneuve fracture. METHODS: The clinical data of 68 patients of Maisonneuve fracture treated with open reduction and internal fixation between October 2012 and October 2016 were retrospectively analyzed. Metallic screw fixation was used in 37 cases (group A) and absorbable screw fixation was used in 31 cases (group B). There was no significant difference in age, gender, weight, operated side, cause of injury, time from injury to operation, and complications between the two groups ( P>0.05). At last follow-up, the tibiafibular clear space (TFCS), tibiafibular overlap (TFO), medial clear space (MCS), and syndesmotic malreduction rate were recorded. And the dorsiflexion and plantar-flexion range of motion, pain visual analogue scale (VAS) score, ankle and hind foot score of American Orthopaedic Foot and Ankle Society (AOFAS), and Olerud-Molander (OM) score were recorded. RESULTS: All patients were followed up 25-43 months, with an average of 32.3 months. There was no significant difference in the operation time between the two groups ( t=1.229, P=0.282). All the fractures healed, and there was no significant difference in fracture healing time between the two groups ( t=1.367, P=0.413). At last follow-up, the syndesmotic malreduction rate of group A was 16.2% (6/37), showing no significant difference when compared with group B [6.2% (2/31)] ( χ 2=1.549, P=0.213). There were 3 complications in group A, 1 was superficial wound infection, 1 was local heterotopic ossification due to failure to remove the screws in time, 1 was local heterotopic ossification of the screws; and there were 2 complications in group B, 1 was rejection and 1 was local heterotopic ossification of the screws. There was no significant difference in the incidence of complications between the two groups ( χ 2=0.068, P=0.794). There was no significant difference in TFCS, MCS, TFO, ankle dorsiflexion and plantar-flexion range of motion, AOFAS score, OM score, and VAS score between the two groups at last follow-up ( P>0.05). CONCLUSION: Compared with metallic screw, absorbable screws provide adequate fixation and functional recovery with avoiding screw removal and lower syndesmotic malreduction.

Sequential fluoroscopic rollover images reliably identify "in-out-in" posterosuperior screws during percutaneous fixation of femoral neck fractures.

INTRODUCTION: Percutaneous screws placed into the posterosuperior femoral neck are frequently extraosseous or "in-out-in" (IOI). These IOI screws are not readily identifiable on anteroposterior (AP) and lateral fluoroscopic images. The purpose of this study was to examine the ability of surgeons to identify IOI guide pins using sequential fluoroscopic rollover images. MATERIALS AND METHODS: A 3.2-mm guide pin was placed into the posterosuperior quadrant of eleven synthetic femur models. Five samples were "all-in" (AI), and six were IOI. Sequential fluoroscopic rollover images were obtained starting with an AP image, then images at 10-degree rollover intervals ending with a direct lateral image. Images were reviewed in a blinded fashion by five attending orthopedic trauma surgeons and 20 resident surgeons to determine whether guide pins were AI or IOI. Accuracy, interobserver reliability, sensitivity, and specificity were assessed. RESULTS: The overall accuracy of responses was 86% with no difference between attending trauma surgeons and residents (p = 0.5). The sensitivity and specificity for an IOI guide pin were 98.0% and 71.2%, respectively. Interobserver reliability among surgeons was good (κ = 0.703). CONCLUSION: The use of the sequential fluoroscopic rollover images after placement of the posterosuperior guide pin into the femoral neck was highly sensitive for detecting an IOI position. The 40-degree rollover image was the best view to evaluate the proximity of the guide pin to the posterior cortex.

The addition of an anti-rotation screw to the dynamic hip screw.

The aim of this study is to assess if there is a difference in outcomes between a dynamic hip screw with or without an anti-rotation screw in the treatment of hip fractures. All patients with an intracapsular hip fracture who underwent dynamic hip screw osteosynthesis between January 2010 and December 2013 in three Dutch hospitals were reviewed. Minimal follow-up was one year. The study included a total of 364 patients. 24 patients were lost to follow-up and excluded. 297 (87.4%) were in the dynamic hip screw group and 43 (12.6%) in the dynamic hip with anti-rotation screw group. Direct comparison of patient characteristics of the two groups showed significant differences in age, sex, Garden classification and Pauwels classification. Patients operated with a dynamic hip screw and anti-rotation screw are significantly younger and their fractures are significantly more dislocated and steeper. To draw conclusions about differences in outcome, a randomised clinical trial should be performed.

Comparative Stiffness of an Equine Distal Sesamoid Bone Fracture Model Stabilized with 3.5-mm versus 4.5-mm Cortical Bone Screws in Lag Fashion.

OBJECTIVE: The aim of this study was to to determine the comparative stiffness following repair of an axial sagittal fracture model in equine distal sesamoid bones using either a single 3.5-mm or 4.5-mm cortical bone screw placed in lag fashion. STUDY DESIGN: The present study was an in vitro biomechanical study. RESULTS: The mean (±standard deviation) stiffness value for the 4.5-mm screw-bone construct (522.49 N/mm ± 168.21) was significantly greater than the 3.5-mm screw-bone construct (408.46 N/mm ± 131.13) (p = 0.047). This represents a 28% difference in mean stiffness. CONCLUSIONS: In vitro, the 4.5-mm screw-bone construct creates a stiffer repair of fractured distal sesamoid bones by a margin of 28%. The 4.5-mm cortical bone screw may better withstand forces imparted on the distal sesamoid bone sustained during anaesthetic recovery, normal weight bearing and athletic exercise, thereby minimizing the risk of implant failure.

Pullout strength of 2.0 mm cancellous and cortical screws in synthetic bone.

OBJECTIVE: To determine whether 2.0 mm cancellous screws are superior to 2.0 mm cortical screws when inserted into cancellous and bicortical bone. STUDY DESIGN: Biomechanical study. METHODS: The 2.0 mm cancellous screws and 2.0 mm cortical screws were inserted according to the recommended guidelines in synthetic cancellous and bicortical blocks. Fifteen screw-block constructs per group were tested to failure in axial pullout. Axial pullout strength and yield strength were calculated. Data were analyzed using a one-way ANOVA. RESULTS: The 2.0 mm cortical screws achieved lower axial pullout strength than 2.0 mm cancellous screws in cancellous blocks. The 2.0 mm cortical screws achieved greater pullout strength than 2.0 mm cancellous screws in bicortical blocks. CONCLUSION: The 2.0 mm cancellous screws may offer a biomechanical advantage in bone with thin cortices (<1 mm thick), whereas 2.0 mm cortical screws may be preferred in cortical bone with cortices measuring at least 1 mm in thickness.

Numerical Optimization of the Position in Femoral Head of Proximal Locking Screws of Proximal Femoral Nail System; Biomechanical Study.

BACKGROUND: Proximal femoral fracture rates are increasing due to osteoporosis and traffic accidents. Proximal femoral nails are routinely used in the treatment of these fractures in the proximal femur. AIMS: To compare various combinations and to determine the ideal proximal lag screw position in pertrochanteric fractures (Arbeitsgemeinschaft für Osteosynthesefragen classification 31-A1) of the femur by using optimized finite element analysis. STUDY DESIGN: Biomechanical study. METHODS: Computed tomography images of patients' right femurs were processed with Mimics. Afterwards a solid femur model was created with SolidWorks 2015 and transferred to ANSYS Workbench 16.0 for response surface optimization analysis which was carried out according to anterior-posterior (-10°0) and posterior-anterior directions of the femur neck significantly increased these stresses. The most suitable position of the proximal lag screw was confirmed as the middle of the femoral neck by using optimized finite element analysis.

Radiographic Review of Helical Blade Versus Lag Screw Fixation for Cephalomedullary Nailing of Low-Energy Peritrochanteric Femur Fractures: There is a Difference in Cutout.

OBJECTIVES: To compare the rate of cutout of helical blades and lag screws in low-energy peritrochanteric femur fractures treated with a cephalomedullary nail (CMN). DESIGN: Retrospective review. SETTING: Academic medical center. PATIENTS: Overall, this study included 362 patients with an average age of 83 year old, a majority of whom were women, and had sustained a low-energy peritrochanteric femur fracture treated with a CMN. All patients had at least 3 months of clinical and radiographic follow, with an average follow-up of 11 months and a range of 3-88 months follow-up. INTERVENTION: Cephalomedullary nailing with the use of a helical blade or single lag screw for proximal fixation. MAIN OUTCOME MEASUREMENTS: Cutout of the helical blade or lag screw. RESULTS: Twenty-two cutouts occurred, 14 (15.1%) of 93 patients with helical blades and 8 (3.0%) of 269 patients with lag screws. Cutout with the helical blade was significantly more frequent than with the lag screw (P = 0.0001). The average tip-apex distance (TAD) was significantly greater for those patients who experienced cutout both for the helical blades (23.5 vs. 19.7 mm; P = 0.0194) and lag screws (24.5 vs. 20.0 mm; P = 0.0197). An absolute TAD predictive of cutout could not be determined. CONCLUSIONS: When the helical blade was used, implant cutout occurred at a significantly higher rate compared with lag screw fixation. There was not a threshold TAD that was predictive of cutout for either implant. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical Evaluation of the Femoral Neck System in Unstable Pauwels III Femoral Neck Fractures: A Comparison with the Dynamic Hip Screw and Cannulated Screws.

OBJECTIVES: To evaluate the biomechanical performance of femoral neck system (FNS) in comparison with established methods for fixation of femoral neck fractures in a cadaveric model. METHODS: Twenty pairs of fresh-frozen human cadaveric femora were instrumented either with dynamic hip screw and antirotation screw (DHS-screw), DHS-blade, 3 cannulated screws (3CS) or with FNS in a partially paired design. The specimens were randomized to 2 paired treatment groups based on the bone mineral density (BMD), namely DHS-screw/DHS-blade and FNS/3CS. A reduced unstable femoral neck fracture with postero-caudal comminution, OTA/AO 31-B2.3, 70 degrees Pauwels III, was simulated by cutting 30 degrees distal and 15 degrees posterior wedges. Cyclic axial loading was applied in 16 degrees adduction, starting at 500 N and with progressive peak force increase of 0.1 N/cycle until construct failure. Axial stiffness was measured in the third loading cycle. Femoral neck and leg shortening, and varus tilting and implant migration were calculated by means of optical motion tracking. RESULTS: Mean axial stiffness was 688.8 ± 132.6 N/mm for DHS-screw, 629.1 ± 94.1 N/mm for DHS-blade, 748.9 ± 211.4 N/mm for FNS, and 584.1 ± 156.6 N/mm for 3CS, with no statistical significances. Cycles until 15-mm leg shortening were comparable for DHS-Screw (20,542 ± 7465), DHS-blade (19,161 ± 3793) and FNS (17,372 ± 2996), however significantly higher than for 3CS (7293 ± 2819), P < 0.001. Similarly, cycles until 15 mm femoral neck shortening were comparable between DHS-screw (20,846 ± 7339), DHS-blade (18,974 ± 4032) and FNS (18,171 ± 2585), and significantly higher than 3CS (8039 ± 2778), P < 0.001. CONCLUSIONS: From a biomechanical point of view, the femoral neck system is a valid alternative to treat unstable femoral neck fractures, representing the advantages of a minimally invasive implant with comparable stability to the 2 DHS systems and superior to cannulated screws.

A novel nail providing more biomechanical rotational and axial stability than conventional interlocking nail in femur complex fracture model.

PURPOSE: Inter-fragmentary rotational and axial instabilities are major challenges in nailing of complex or comminuted fractures. We aimed to compare the inter-fragmentary rotational and axial stability of novel anti-rotation interlocking nail and the conventional interlocking nail in complex or comminuted femur shaft fractures. METHODS: Twenty composite femurs were divided into two groups, 30 mm was resected from the mid-portion of all composite femurs. The inter-fragmentary rotational and axial stabilities were assessed. RESULTS: Between 10-N m external and 6-N m internal rotation torques, mean maximum inter-fragmentary rotational arc motion in the novel nails was 1.63 mm and 291 % less than that of the conventional nails (6.38 mm, P = 0.000). Between 150 N distraction and 2300 N compression, mean axial motion in the novel nails was 0.8 mm and 257 % less than that of the conventional nails (2.86 mm, p = 0.000). CONCLUSION: An anti-rotational novel nail is superior to the conventional interlocking nail in terms of maximum inter-fragmentary rotational and axial stabilities in complex and comminuted femur shaft fractures.

A novel classification of screw placement accuracy in the cervical spine.

BACKGROUND: Goal of this study is to present an easily reproducible and reliable measurement to evaluate accuracy of screw placement in cervical spine. METHODS: Accuracy of cervical screw position was assessed in 52 patients treated with 163 screws. Each patient receiving pedicle, transarticular C1/2, lateral mass, or laminar screws and postoperative CT scan was included. Placement position was categorized in 5 grades: Grade 1 is ideal with pedicle wall perforation < 1 mm, grade 2 < 2 mm, grade 3 < 3 mm, and grade 4 < 4 mm. Grade 5 > 4 mm and/or obstruction of transverse foramen by more than half a screw diameter. Intraclass correlation coefficient (ICC) values were assessed for inter- and intraobserver reliability. RESULTS: The mode of individual evaluations was calculated to assign a single value to each screw. This yielded 89 grade 1 (54.6%), 48 grade 2 (29.4%), 14 grade 3 (8.6%), 3 grade 4 (1.8%), and 9 grade 5 (5.5%) screws. Intraobserver reliability ICC was 0.966 and 0.959 for measurements. Interobserver reliability ICC was 0.938. CONCLUSION: This study introduces a reliable classification of cervical spine instrumentation with various screw types. This should enable the use of a uniform and reproducible, and thus comparable classification for screw position in cervical spine.

Mechanical Construct Characteristics Predisposing to Non-union After Locked Lateral Plating of Distal Femur Fractures.

OBJECTIVES: To identify discrete construct characteristics related to overall construct rigidity that may be independent predictors of nonunion after lateral locked plate (LLP) fixation of distal femur fractures. DESIGN: Retrospective case-control study. SETTING: Three level-1 urban trauma centers. PATIENTS/PARTICIPANTS: Two hundred and seventy-one supracondylar femoral fractures treated with LLP at 3 affiliated level 1 urban trauma centers between August 2004 and December 2010. METHODS: Nonunion was defined as a secondary procedure for poor healing. Construct variables included: (1) combined plate design and material variable, (2) Plate length, (3) # screws proximal to fracture, (4) total screw density (TSD), (5) proximal screw density (PSD), (6) presence of a screw crossing the main fracture, and (7) rigidity score multivariable analysis was performed using logistic regression to identify independent risk factors for nonunion. INTERVENTION: LLP fixation. MAIN OUTCOME MEASURE: Nonunion. RESULTS: Nonunion rate was 13.3% (n = 36). There was a significant association between plate design/material and nonunion with 41% of stainless constructs and 10% of titanium constructs resulting in a nonunion (P < 0.001). Rigidity scores reached significance (P = 0.001) with constructs resulting in a nonunion having higher scores. No significant univariate differences with respect to number of proximal screws, plate length, total screw density, or proximal screw density were observed between healed fractures and those with nonunion. Results of the multivariate analysis confirmed that the primary significant independent predictor of nonunion was plate design/material (odds ratio, 6.8; 95% CI, 2.9-16.1; P < 0.001). CONCLUSIONS: When treating distal femur fractures with LLP, combined plate design and material variable has a highly significant influence on the risk of nonunion independent of any other construct variable. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparison of Direct Pars Repair Techniques of Spondylolysis in Pediatric and Adolescent Patients: Pars Compression Screw Versus Pedicle Screw-Rod-Hook.

STUDY DESIGN: Retrospective clinical cohort study. OBJECTIVE: To compare the clinical and radiographic outcomes of patients who were treated with intrasegmental pars fixation by either laminar compression screw (LS) or a pedicle screw, rod, and laminar hook (PSRH) construct. SUMMARY OF BACKGROUND DATA: Spondylolysis is a nonunion defect of the pars interarticularis. In symptomatic spondylolysis, direct repair of the pars interarticularis defect can preserve motion and prevent abnormal stresses at the adjacent levels. METHODS: Sixteen patients who failed nonoperative treatment and underwent direct pars repair by using LS (n=9) or PSRH (n=7) constructs were included in the study. Clinical outcome was assessed by using the MacNab criteria. Radiologic fusion and complications were evaluated using plain radiographs or computed tomography images and patient charts. RESULTS: The healing rate was 100% after 6 months. The healing time was similar in both the groups: LS, 6.5 months; PSRH, 6.2 months. Patients with PSRH (5.9 mo) were more likely to return to sports earlier relative to patients with LS (7.7 mo). There were no complications in the LS group; in the PSRH group, 1 patient had mild sensory deficit and 2 had superficial wound infections. The MacNab criteria for pain assessment showed an excellent or good outcome in 8 of 9 patients in LS group and 6 of 7 patients in PSRH group. Relative to LS patients, there was a significant increase in surgical time and estimated blood loss among PSRH patients. CONCLUSIONS: Either of the mentioned 2 techniques appears to produce acceptable results. Biplanar fluoroscopy and navigation systems could minimize the risk of screw misplacement with LS construct. Familiarity with the various fixation techniques will allow the surgeon to select the most appropriate surgical technique.

Biomechanical comparison of headless antegrade screw versus retrograde cortical screw for coronoid fracture fixation.

OBJECTIVE: Posterior-to-anterior directed screws are stronger than anterior-to-posterior directed screws for coronoid fracture fixation. Anterior approaches that facilitate direct reduction and fixation of coronoid fractures have been described. The present study was based on the hypothesis that anterior-to-posterior headless screw (Acutrak Mini® 3.5 mm × 26 mm, Acumed, Hillsboro, Oregon, USA) fixation of coronoid fractures would be as strong as posterior-to-anterior 2.7 mm Association for Osteosynthesis (AO) cortical screw fixation. METHODS: This study included 14 ulnas obtained from 14 formalin-preserved adult cadavers. Coronoid type 2 fractures were created and fixed randomly using anterior-to-posterior headless screws (antegrade group) and posterior-to-anterior 2.7 mm AO cortical screws (retrograde group). The experimental constructs were loaded until 2 mm of displacement. Failure load (N), fixation stiffness (Nmm-1), and indentation stiffness were calculated. RESULTS: Failure load was higher in the retrograde screw group (p=0.03), whereas loading stiffness values of the fixation devices and bones did not differ between the 2 fixation groups (p>0.05). CONCLUSION: The present study failed to show that anterior-to-posterior directed headless screw fixation of coronoid fractures could adequately replace posterior-to-anterior placed screw fixation.

Nuts and bolts: dimensions of commonly utilized screws in upper extremity surgery.

A plethora of screw designs and sizes are available from multiple companies for use in upper extremity surgery. Knowing the dimensions of screws is critical in the treatment of bone of varying dimensions for fractures, osteotomies, or arthrodeses. Although many screws are named by their major thread diameter, this is not always true. Because of this confusing nomenclature and vast number of options, we sought to review the most commonly used screws and codify their dimensions into a readily available article and reference chart. This article highlights the basic dimensions of commonly used headless screws, stand-alone lag screws, non-locking and locking screws for plating, and biocomposite screws. Commonly described treatments using these screws include fixation of elbow, wrist, carpal, metacarpal, and phalangeal fractures and osteotomies, as well as arthrodeses of upper extremity joints. This article and its tables are by no means exhaustive of all commercially available implants. The focus is on the most commonly used implants in the United States as of 2014.

"The Skiver Screw": A Useful Fixation Technique for Iliac Wing Fractures.

The contour of the ilium is curved and the iliac fossa is thin, making adequate fixation for fractures involving the iliac wing challenging to achieve at times. The purpose of this article is to describe a previously unreported technique for enhancing fixation in iliac fractures using simple cortical screws.

Biomechanical comparison of antirotator compression hip screw and cannulated screw fixations in the femoral neck fractures.

OBJECTIVE: The aim of this study was to compare the biomechanical properties of minimal invasive sliding antirotator compressive hip screw (MIS-A-CHS), and multiple cannulated screws (CS) on a Pauwels type 3 femoral neck fracture model. METHODS: A Pauwels type 3 vertical femoral neck fractures was created on 12 third-generation proximal femur models which were divided into two equal groups. The fracture was fixed with three CS in the first group, and MIS-A-CHS in the second group. The axial and rotational stiffness and maximum compression effect were compared between the groups. RESULTS: The axial and rotational stiffness and maximum compression were significantly higher in MIS-A-CHS group (912.5 N, 540 N and 10.2 N/m, respectively) than the CS group (627.5 N, 380 N, and 3.9 N/m, respectively). CONCLUSION: MIS-A-CHS appears to be a more secure fixation method in Pauwels type 3 femoral neck fractures than the CS.

Microtornillos: Una revisión / Miniscrews: A revision

Los microtornillos son un tipo de implante alveolar que proporcionan un método excelente de anclaje. Por su parte, los microtornillos son un elemento económico, fácil de colocar y retirar. Se realiza una revisión del procedimiento quirúrgico y de su utilización clínica y se analizan las ventajas, los inconvenientes y las posibles complicaciones. Se llega a la conclusión de que el procedimiento de inserción de los microtornillos es tan sencillo, que permite su utilización incluso en situaciones clínicas que presentan disminución del soporte dentario. La estabilidad a largo plazo es predecible y fiable y han constituido un impulso para eliminar la cooperación del paciente, además de conseguir resolver problemas relacionados con el control del anclaje dentario. Entre sus principales indicaciones se encuentran los siguientes movimientos dentarios: intrusión de molares, retrusión de incisivos y de la intrusión de incisivos entre otras. En los últimos años, se han diseñado implantes de dimensiones pequeñas para situarlos en cualquier superficie del proceso alveolar, incluso en áreas interdentales. Son relativamente económicos, y las técnicas de colocación y desinserción son simples. Como todo elemento que se inserta en la cavidad bucal, es necesario hacer un estudio radiográfico exhaustivo. No debemos olvidar que estos implantes se colocan entre raíces o en zonas próximas de los dientes. Se han reportado numerosos artículos sobre la lesión periodontal y radicular al insertarlos, éste es el motivo por el cual daremos importancia a este aspecto y detallaremos el procedimiento a seguir en la planificación de la técnica y en las complicaciones que pueden surgir si no se lleva a cabo

The microscrews are a kind of alveolar implant that bring an excellent method of anchorage. Besides, the microscrews are an economic element, easy to place and remove. We carry out the checking of the surgical procedure, and its clinical use; we analize the advantages, disadvantages and draw backs. We finally come to the conclusion that the insertion procedure of the miniscrews is so easy that it allows its use even in clinic situations that show a decrease of the dental support. In the long term, the microimplants bring a predictable and reliable stability and those ones, have reduced the cooperation of the patient; besides solving problems linked to the control of the dental anchorage. Among the main indications, we can find the following dental movements: molar intrusion, incisive retrusion and incisive intrusion among others. In the last years, they have designed miniimplants in order to place them in any surface of the alveolar process even between interdental areas. The miniscrews are quiet cheap, and the techniques of placement and removal are simply. As all the elements are located in the mouth cavity, an exhaustive radiografic study is of far reaching important. We must not forget that those implants are placed between the roots or in areas close to the teeth. Several articles on the periodontal and root damage have been written, reason why we will focus on those damages and we will proceed to detail the planning procedure of this technique and the draw back that can arise, if those procedure is not followed

How to prevent cut-out and cut-through in biaxial proximal femoral nails: is there anything beyond lag screw positioning and tip-apex distance?

PURPOSE: Hip perforation is a major complication in proximal femoral nailing. For biaxial nails, knowledge of their biomechanics is limited. Besides re-evaluation of accepted risk factors like the tip-apex distance (TAD), we analysed the influence of anti-rotational pin length. METHODS: We compared 22 hip perforation cases to 50 randomly chosen controls. TAD, lag-screw position, angle between lag-screw and femoral neck axis, lag-screw gliding capacity, displacement and anti-rotational pin length were investigated. RESULTS: Hip perforation was associated with a higher angle of deviation between lag-screw and femoral neck axis (p = 0.001), a lower telescoping capacity of the lag screw (p = 0.02), and higher TAD (p = 0.048). If the anti-rotational pin exceeded a line connecting the tip of the nail and the lag screw (NS line), hip perforation incidence was increased (p = 0.009). Inadequate pin length resulted in an odds ratio of 10.8 for hip perforation (p = 0.001). CONCLUSIONS: In biaxial nails anti-rotational element positioning is underestimated, however, crucial.