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Thoracic pedicle screw insertion in Asian cadaveric specimen: does radiological pedicle profile affect outcome?

Chan CY, Kwan MK, Saw LB

Surg Radiol Anat, 2011 Jan;33(1):19-25.
PMID: 20848102 DOI: 10.1007/s00276-010-0726-1

Pedicle screw instrumentation has superior biomechanical as well as clinical outcome. Thoracic pedicles show great variation in different population groups, particularly in Asians who have been shown to have smaller pedicle dimensions. Although plain radiographs are widely performed prior to spine surgery, no studies have been done so far to investigate whether the thoracic pedicle profile on plain radiographs affect thoracic pedicle screw insertion. Therefore, this is a cadaveric study aimed to determine the relationship between plain radiographic thoracic pedicle profile in Asians and the outcome of pedicle screw insertion in the thoracic spine.

Matched MeSH terms: Bone Screws*
Fulltext A Novel Technique for Fixation of Non-union Unicondylar Hoffa's Fracture: A Case Report

Harna B, Dutt DD, Sabat D

Malays Orthop J, 2020 Nov;14(3):174-176.
PMID: 33403081 DOI: 10.5704/MOJ.2011.028

Hoffa fractures are rare and difficult fractures to manage. Hoffa fracture involves a coronal plane fracture of posterior femoral condyle. Non-union in Hoffa fracture is further difficult to manage. The surgical management for such nonunion includes open reduction with recon/LCP plate or screw fixation with bone grafting. The problem with plates is the difficulty in contouring the plates according to the shape of posterior femoral condyles. We describe a new technique with 2 L shaped neutralisation plates placed in a circular fashion. This technique provides a more rigid construct and gives better holding strength of screws in Hoffa fragment. This enhances union and mobilisation can be started early.

Matched MeSH terms: Bone Screws
Fulltext Radiographic imaging of steel oval lock carabiner by using computed radiography: a pilot study

Nadzirah Mohamad Radzi, Zafri Azran Abdul Majid

International Journal of Allied Health Sciences, 2018;2(2):310-318.
MyJurnal

Carabiner is one of Personal Protective Equipment (PPE), which is used to protect the users from hazards by reducing any chance of serious injury. Thus, it is very important to detect even a small
defect on the component before it becomes worse that could give harm to the users. The aim of this paper is to find out the appropriate imaging technical factors of steel carabiner by using computed radiography (CR). Methods: Radiographic images of carabiner were obtained by manipulating the values of kVp and mAs with respect to contrast and density. A preliminary study was carried out to determine the exposure factor combination in order to produce perceptible visual quality of radiographic images. Positioning techniques applied in this study were whole view (open-gate and close-gate position) and screw view (open-gate and close-gate position). An assessor was invited to evaluate the radiographs by using Image Quality Criteria Scoring (ICS) adapted from European Guidelines on Quality Criteria for Diagnostic Radiographic Images. Results: Findings showed that the optimum values of kVp and mAs in imaging whole view (open-gate and close-gate) carabiner were 133 kVp and 28 mAs while, for screw view (opengate and close-gate) the range of kVp and mAs preferred were 121 kVp to 133 kVp and 28 mAs to 36 mAs respectively. Conclusion: This study has found that the use of medical CR to expose metal steel such as
carabiner is accepted. By manipulating the imaging parameters, CR can produce a good quality image of carabiner.

Matched MeSH terms: Bone Screws
The effects of additional hollow cylinder coated to external fixator screws for treating pilon fracture: A biomechanical perspective

Ramlee MH, Seng GH, Ros Felip A, Abdul Kadir MR

Injury, 2021 Aug;52(8):2131-2141.
PMID: 33745700 DOI: 10.1016/j.injury.2021.03.017

An external fixator is a promising medical device that could provide optimum stability and reduce the rate of complications in treating bone fracture during intervention period. It is noted that the biomechanics behaviour of device can be altered by introducing more features such as material suitability and additional components. Therefore, this study was conducted via finite element method to investigate the effects of additional hollow cylinder coated with external fixator screws in treating Type III pilon fracture. Finite element models which have been validated with experimental data were used to simulate stresses at the pin-bone interface and relative micromovement at interfragmentary fractures during swing (70 N load) and stance phases (350 N load). All bones and external fixators were assigned with isotropic material properties while the cartilages were simulated with hyper-elastic. For the hollow cylinder, polyethylene was assigned due to its properties which are equivalent to the bone. From the results, it is found that stresses at the pin-bone interface for the coated screws were reduced to 54% as compared to the conventional fixator. For the micromovement, there was no difference between both models, whereby the value was 0.03 mm. The results supported previously published literature, in which high stresses are unavoidable at the interface, fortunately, those stresses did not exceed the ultimate strength of bone, which is safe for treating patients. In conclusion, if patients are allowed to bear weight bearing, the external fixator with coated screws is a more favourable option to be fixed into the bone to avoid complications at the interface.

Matched MeSH terms: Bone Screws
Bioresorbable Mg-Based Metastable Nano-Alloys for Orthopedic Fixation Devices

Yan L, Zhang M, Wang M, Guo Y, Zhang X, Xi J, et al.

J Nanosci Nanotechnol, 2020 03 01;20(3):1504-1510.
PMID: 31492313 DOI: 10.1166/jnn.2020.17350

This research has been accomplished using the advanced selective laser melting (SLM) technique as well as HIP post-treatment in order to improve mechanical properties and biocompatibility of Mg- Ca-Sr alloy. Through this research it becomes clearly noticeable that the Mg-1.5Ca-xSr (x = 0.6, 2.1, 2.5) alloys with Sr exhibited better mechanical properties and corrosion potentials. This is more particular with the Mg-1.5Ca-2.5Sr alloy after HIP post-treatment allowing it to provide a desired combination of degradation and mechanical behavior for orthopedic fracture fixation during a desired treatment period. In vivo trials, there was a clear indication and exhibition that this Mg-1.5Ca-2.5Sr alloy screw can completely dissolve in miniature pig's body which leads to an acceleration in growth of bone tissues. Mg-Ca-Sr alloy proved potential candidate for use in orthopedic fixation devices through Our results concluded that Mg-Ca-Sr alloy are potential candidate for use in orthopedic fixation devices through mechanical strength and biocompatibility evaluations (in vitro or In vivo).

Matched MeSH terms: Bone Screws
Fulltext A Technique for Removal of Forearm Dynamic Compression Plate with Stripped Screws: A Report of Three Cases

Lee, C.K., Kwan, M.K., Chua, Y.P.

Malays Orthop J, 2009;3(1):85-87.
MyJurnal

Removal of plates is a procedure commonly performed by orthopaedic surgeons and stripped screws are probably the most common problem encountered during this procedure. Stripped screws are caused by slippage between the screwdriver and the screw. Due to the inherent difficulty in removing such screws, surgeons should be knowledgeable in techniques for their removal and should be equipped with the proper instruments to expedite the procedure. There are few published articles about such techniques. This report describes a technique for removal of plates with stripped screws. The tip of a stripped screw is approached from the far cortex and then reamed with a trephine reamer in the direction of the screw until both cortices are cleared. The plate is then removed with stripped screws attached. All the removals utilizing this technique to date have been successful with no complications, and this method is safe, efficient and technically easy to learn.

Matched MeSH terms: Bone Screws
Fulltext Outcome of anterior cruciate ligament reconstruction: a comparison between biotransfix screw and all-inside technique

Nik Alyani Nik Abdul Adel, Mohd Shukrimi bin Awang, Zamzuri bin Zakaria

International Medical Journal Malaysia, 2017;16(11):35-35.
MyJurnal

Anterior cruciate ligament (ACL) reconstruction has evolved during past
decade. All inside technique is introduced aiming for less invasive procedure, bone stock
preservation, preservation of tendon at its donor site, better graft positioning and
fixation technique. This study is conducted to compare the outcomes of this new
technique to the previous biotransfix screw. (Copied from article).

Matched MeSH terms: Bone Screws
Fulltext Well-Dispersed Cellulose Nanofiber in Low Density Polyethylene Nanocomposite by Liquid-Assisted Extrusion

Yasim-Anuar TAT, Ariffin H, Norrrahim MNF, Hassan MA, Andou Y, Tsukegi T, et al.

Polymers (Basel), 2020 Apr 17;12(4).
PMID: 32316664 DOI: 10.3390/polym12040927

Two different liquid assisted processing methods: internal melt-blending (IMB) and twin-screw extrusion (TWS) were performed to fabricate polyethylene (PE)/cellulose nanofiber (CNF) nanocomposites. The nanocomposites consisted maleic anhydride-grafted PE (PEgMA) as a compatibilizer, with PE/PEgMA/CNF ratio of 97/3/0.5-5 (wt./wt./wt.), respectively. Morphological analysis exhibited that CNF was well-dispersed in nanocomposites prepared by liquid-assisted TWS. Meanwhile, a randomly oriented and agglomerated CNF was observed in the nanocomposites prepared by liquid-assisted IMB. The nanocomposites obtained from liquid-assisted TWS exhibited the best mechanical properties at 3 wt.% CNF addition with an increment in flexural strength by almost 139%, higher than that of liquid-assisted IMB. Results from this study indicated that liquid feeding of CNF assisted the homogenous dispersion of CNF in PE matrix, and the mechanical properties of the nanocomposites were affected by compounding method due to the CNF dispersion and alignment.

Matched MeSH terms: Bone Screws
Fulltext Augmentation of the Delamination Factor in Drilling of Carbon Fibre-Reinforced Polymer Composites (CFRP)

Ahmad Sobri S, Whitehead D, Mohamed M, Mohamed JJ, Mohamad Amini MH, Hermawan A, et al.

Polymers (Basel), 2020 Oct 23;12(11).
PMID: 33114223 DOI: 10.3390/polym12112461

Carbon fibre-reinforced polymer (CFRP) composite materials play an increasingly important role in modern manufacturing, and they are among the more prominent materials used in aircraft manufacturing today. However, CFRP is highly prone to delamination and other damage when drilled due to it being extremely strong with a good strength-to-weight ratio and high thermal conductivity. Because of this problem and CFRP's growing importance in aircraft manufacture, research has focused on the entry and exit holes as indicators of damage occurrence during drilling of screws, rivets, and other types of holes. The inside of the hole was neglected in past research and a proper way to quantify the internal side of a hole by combining the entry and exit hole should be included. To fill this gap and improve the use of CFRP, this paper reports a novel technique to measure the holes by using the extension of the adjusted delamination factor (SFDSR) for drilling thick CFRP composites in order to establish the influence of machining input variables on key output measures, i.e., delamination and other damages. The experimental results showed a significant difference in interpretation of the damage during the analysis. Improvement was made by providing better perspectives of identifying hole defects.

Matched MeSH terms: Bone Screws
Fulltext Crystal structure of 3-hy-droxy-methyl-1,2,3,4-tetra-hydro-isoquinolin-1-one

Caracelli I, Hino CL, Zukerman-Schpector J, Biaggio FC, Tiekink ER

Acta Crystallogr E Crystallogr Commun, 2015 Aug 1;71(Pt 8):o558-9.
PMID: 26396795 DOI: 10.1107/S2056989015012670

In the title compound, C10H11NO2, two independent but virtually superimposable mol-ecules, A and B, comprise the asymmetric unit. The heterocyclic ring in each mol-ecule has a screw-boat conformation, and the methyl-hydroxyl group occupies a position to one side of this ring with N-C-C-O torsion angles of -55.30 (15) (mol-ecule A) and -55.94 (16)° (mol-ecule B). In the crystal, O-H⋯O and N-H⋯O hydrogen bonding leads to 11-membered {⋯HNCO⋯HO⋯HNC2O} heterosynthons, involving three different mol-ecules, which are edge-shared to generate a supra-molecular chain along the a axis. Inter-actions of the type C-H⋯O provide additional stability to the chains, and link these into a three-dimensional architecture.

Matched MeSH terms: Bone Screws
Fulltext Dynamic hip screw compared to condylar blade plate in the treatment of unstable fragility intertrochanteric fractures

Yong CK, Tan CN, Penafort R, Singh DA, Varaprasad MV

Malays Orthop J, 2009;3(1):13-18.
MyJurnal

Dynamic hip screw (DHS) fixation is considered standard treatment for most intertrochanteric fractures. However, excessive sliding at the fracture site and medialisation of femoral shaft may lead in fixation failure. In contrast, fixed-angled 95Â° condylar blade plate (CBP) has no effective dynamic capacity and causes little bone loss compared to DHS. We compared the outcome of 57consecutive unstable intertrochanteric fragility fractures treated with these two fixation methods. CBP instrumentation is more difficult requiring longer incision, operating time and higher surgeon-reported operative difficulty. The six month post-operative mortality rate is 16%. Post-operative Harris hip scores were comparable between the two methods. Limb length shortening more than 20 mm was 6-fold more common with DHS. In elderly patients with unstable intertrochanteric fragility fractures, fixed angled condylar blade plate appears to be a better choice than dynamic hip screws for preventing fixation failures.

Matched MeSH terms: Bone Screws
Fulltext Cannulated screw fixation for femoral neck fractures: a 5-year experience in a single institution

Khoo, C. C. H., Amber Haseeb, Vivek Ajit Singh

Malays Orthop J, 2014;8(2):14-21.
MyJurnal

Cannulated screw fixation is a widely accepted surgical method for management of fractures of the neck of femur especially in patients with poor premorbid conditions, minimally displaced fractures and those from a younger age group. A five year retrospective study was carried out in 53 consecutive patients between 2006 to 2010 to determine the pattern of injuries, management, outcomes and the associated predictive factors.All the patients underwent cannulated screw fixation, with 37 (69.8%) having had surgery within 24 hours and the remaining 16 (30.2%) 24 hours after the initial injury. All patients were followed up to union of fractures and complications thereafter if any. Good outcome was observed in 43 (81.1%) patients leaving only 10 (18.9%) patients with a poor outcome, of whom nine developed avascular necrosis (90%) and one non-union (10%). We found no significant relationship between the incidence of avascular necrosis and age of patient, fracture displacement, numbers of cannulated screws used, fracture reduction acceptability and anatomical location of the fracture. The time interval from injury to surgery and the presence of posterior comminution did seem to influence the rate of avascular necrosis but due to the small number of patients, was not statistically significant.We conclude that cannulated screw fixation is a viable option of treatment for fractures of the neck of femur.

Matched MeSH terms: Bone Screws
Fulltext Flow behaviour and viscoelasticity of polypropylene-kaolin composites extruded at different temperatures

Nor Azura Abdul Rahim, Zulkifli Mohamad Ariff, Azlan Ariffin

Pertanika Journal of Science & Technology, 2011;19(2):383-388.
MyJurnal

A study of kaolin addition in polypropylene (PP-kaolin) melt was carried out to characterize its flow behaviour and viscoelasticity at different temperatures. The compound of 20 wt% kaolin was prepared by melt mixing using two roll-mill heated at 185°C, while the compounded composites were put through a single screw extruder to evaluate its melt flow properties. The prepared PPKaolin composites exhibited a shear thinning behaviour and appeared to be strongly dependent on temperature. Moreover, it was also found that the power law index was constantly increased as the temperature increased. Meanwhile, a similar trend was observed for swelling ratio, whereby it also increased with increasing temperature. It was also observed that changes in the die temperatures would result in the formation of obvious bubble like surface morphology, and it became more prominent when the temperature was lowered.

Matched MeSH terms: Bone Screws
Fulltext Measurement of Fracture Strength of Zirconia Dental Implant Abutments with Internal and External Connections Using Acoustic Emission

Soo SY, Silikas N, Satterthwaite J

Materials (Basel), 2019 Jun 23;12(12).
PMID: 31234580 DOI: 10.3390/ma12122009

A single paragraph of about 200 words maximum. For research articles, abstracts should give a pertinent overview of the work. We strongly encourage authors to use the following style of structured abstracts, but without headings: (1) Background: Place the question addressed in a broad context and highlight the purpose of the study; (2) Methods: Describe briefly the main methods or treatments applied; (3) Results: Summarize the article's main findings; and (4) Conclusions: Indicate the main conclusions or interpretations. The abstract should be an objective representation of the article, it must not contain results which are not presented and substantiated in the main text and should not exaggerate the main conclusions. Please add in this section. The aim of the study was to investigate the fracture behaviour of four different groups of zirconia abutments with internal and external connections: (A) Astra Tech ZirDesign™ abutment on Astra Tech Implants, (B) Procera® Esthetic abutment on Nobel Biocare MK III Groovy Implants, (C) IPS e.max® on Straumann Implants, and (D) ZiReal® Posts on Biomet 3I implants. The load was applied on the assemblies using a Zwick universal testing machine: the initial and final failure loads and amplitude were recorded using acoustic emission technique. Mean initial and final failure force was found to be significantly different in each group (P < 0.001). IPS e.max® Straumann abutments exhibited the highest resistance to final fracture force compared to other abutment types. Acoustic emission can be used as one of the methods to detect fracture behaviour of implant abutments. There were no significant differences in fracture loads between the internal and externally connected zirconia abutments studied. However, externally connected abutments demonstrated screw loosening and some deformations.

Matched MeSH terms: Bone Screws
Fulltext Passive Fit in Screw Retained Multi-unit Implant Prosthesis Understanding and Achieving: A Review of the Literature

Buzayan MM, Yunus NB

J Indian Prosthodont Soc, 2014 Mar;14(1):16-23.
PMID: 24604993 DOI: 10.1007/s13191-013-0343-x

One of the considerable challenges for screw-retained multi-unit implant prosthesis is achieving a passive fit of the prosthesis' superstructure to the implants. This passive fit is supposed to be one of the most vital requirements for the maintenance of the osseointegration. On the other hand, the misfit of the implant supported superstructure may lead to unfavourable complications, which can be mechanical or biological in nature. The manifestations of these complications may range from fracture of various components in the implant system, pain, marginal bone loss, and even loss of osseointegration. Thus, minimizing the misfit and optimizing the passive fit should be a prerequisite for implant survival and success. The purpose of this article is to present and summarize some aspects of the passive fit achieving and improving methods. The literature review was performed through Science Direct, Pubmed, and Google database. They were searched in English using the following combinations of keywords: passive fit, implant misfit and framework misfit. Articles were selected on the basis of whether they had sufficient information related to framework misfit's related factors, passive fit and its achievement techniques, marginal bone changes relation with the misfit, implant impression techniques and splinting concept. The related references were selected in order to emphasize the importance of the passive fit achievement and the misfit minimizing. Despite the fact that the literature presents considerable information regarding the framework's misfit, there was not consistency in literature on a specified number or even a range to be the acceptable level of misfit. On the other hand, a review of the literature revealed that the complete passive fit still remains a tricky goal to be achieved by the prosthodontist.

Matched MeSH terms: Bone Screws
Fulltext Cannulated Screw Fixation For Femoral Neck Fractures : A 5-year Experience In A Single Institution

Khoo C, Haseeb A, Ajit Singh V

Malays Orthop J, 2014 Jul;8(2):14-21.
PMID: 25279087 DOI: 10.5704/MOJ.1407.010

Cannulated screw fixation is a widely accepted surgical method for management of fractures of the neck of femur especially in patients with poor premorbid conditions, minimally displaced fractures and those from a younger age group. A five year retrospective study was carried out in 53 consecutive patients between 2006 to 2010 to determine the pattern of injuries, management, outcomes and the associated predictive factors.All the patients underwent cannulated screw fixation, with 37 (69.8%) having had surgery within 24 hours and the remaining 16 (30.2%) 24 hours after the initial injury. All patients were followed up to union of fractures and complications thereafter if any. Good outcome was observed in 43 (81.1%) patients leaving only 10 (18.9%) patients with a poor outcome, of whom nine developed avascular necrosis (90%) and one non-union (10%). We found no significant relationship between the incidence of avascular necrosis and age of patient, fracture displacement, numbers of cannulated screws used, fracture reduction acceptability and anatomical location of the fracture. The time interval from injury to surgery and the presence of posterior comminution did seem to influence the rate of avascular necrosis but due to the small number of patients, was not statistically significant.We conclude that cannulated screw fixation is a viable option of treatment for fractures of the neck of femur.

Matched MeSH terms: Bone Screws
Fulltext Femoral Neck Non-Union - A Biomechanical Solution with Valgus Sliding Subtrochanteric Osteotomy: A Case Report

Teh KH, Ruben JK, Chan CK, Abbas AA

Malays Orthop J, 2020 Jul;14(2):134-137.
PMID: 32983389 DOI: 10.5704/MOJ.2007.022

Avascular necrosis and non-union are two most dreaded complications of femoral neck fracture fixations. Hip replacement seems to be a simple solution for this complex problem. However, the long-term efficacy of prosthetic replacement in the young population with higher functional demand is still questionable. Femoral head preserving valgus subtrochanteric osteotomies in properly selected cases have strong support from literature. The conventional technique of valgus subtrochanteric osteotomy involves lateral based wedge resection. Alternatively, a simpler sliding oblique subtrochanteric osteotomy without any wedge removal can also be performed. We hereby describe a successful case of sliding subtrochanteric osteotomy with 135° dynamic hip screw (DHS) plate fixation in treating non-union neck of femur fracture in a young gentleman.

Matched MeSH terms: Bone Screws
Fulltext Screw Migration into Colon after Anterior Cervical Plating - An Unusual Complication: A Case Report

Sath S

Malays Orthop J, 2020 Nov;14(3):184-187.
PMID: 33403084 DOI: 10.5704/MOJ.2011.031

Complications in the form of esophageal injury, tracheal injury, injury to carotids, implant failure, loosening of screws, etc do occur after anterior cervical surgeries. Although intra-operative esophageal injuries are as such rare, there have been few reports of delayed esophageal perforation as well after anterior cervical surgeries. We report a very rare case of migration of missing screw from anterior cervical plate after anterior cervical corpectomy and plating, which had ultimately migrated down to colon and had to be removed via colonoscopy. Along with removal of migrated screw from colon, revision of failed anterior cervical surgery was done wherein plate and screws were removed with mesh cage left in-situ as it was snug-fit while pharyngeophageal perforation was explored and was found to be spontaneously healing, with addition of posterior Bohlman's interspinous wiring for added stability. Migration of screw from the anterior cervical plate into the colon although very rare, should be always kept in mind and its potentially serious complications. We also conclude that particular attention should be given to elderly people with poor bony quality who have high chances of implant failure, along with attention to proper cage size, screw position and proper locking of the screw to further lessen the chances of implant failure.

Matched MeSH terms: Bone Screws
Fulltext Radiological assessment of cervical lateral mass screw angulations in Asian patients

Sureisen M, Saw LB, Wei Chan CY, Singh DA, Kwan MK

Indian J Orthop, 2011 Nov;45(6):504-7.
PMID: 22144742 DOI: 10.4103/0019-5413.87118

BACKGROUND: Various lateral mass screw fixation methods have been described in the literature with various levels of safety in relation to the anterior neurovascular structures. This study was designed to radiologically determine the minimum lateral angulations of the screw to avoid penetration of the vertebral artery canalusing three of the most common techniques: Roy-Camille, An, and Magerl.
MATERIALS AND METHODS: Sixty normal cervical CT scans were reviewed. A minimum lateral angulation of a 3.5 mm lateral mass screw which was required to avoid penetration of the vertebral artery canal at each level of vertebra were measured.
RESULTS: The mean lateral angulations of the lateral mass screws (with 95% confidence interval) to avoid vertebral artery canal penetration, in relation to the starting point at the midpoint (Roy-Camille), 1 mm medial (An), and 2 mm medial (Magerl) to the midpoint of lateral mass were 6.8° (range, 6.3-7.4°), 10.3° (range, 9.8-10.8°), and 14.1° (range, 13.6-14.6°) at C3 vertebrae; 6.8° (range, 6.2-7.5°), 10.7° (range, 10.0-11.5°), and 14.1° (range, 13.4-14.8°) at C4 vertebrae; 6.6° (range, 6.0-7.2°), 10.1° (range, 9.3-10.8°), and 13.5° (range, 12.8-14.3°) at C5 vertebrae and 7.6° (range, 6.9-8.3°), 10.9° (range, 10.3-11.6°), and 14.3° (range, 13.7-15.0°) at C6 vertebrae. The recommended lateral angulations for Roy-Camille, Magerl, and An are 10°, 25°,and 30°, respectively. Statistically, there is a higher risk of vertebral foramen violation with the Roy-Camille technique at C3, C4 and C6 levels, P < 0.05.
CONCLUSIONS: Magerl and An techniques have a wide margin of safety. Caution should be practised with Roy-Camille's technique at C3, C4, and C6 levels to avoid vertebral vessels injury in Asian population.

Matched MeSH terms: Bone Screws
Fulltext Impact of Bone Cement Augmentation on the Fixation Strength of TFNA Blades and Screws

Sermon A, Hofmann-Fliri L, Zderic I, Agarwal Y, Scherrer S, Weber A, et al.

Medicina (Kaunas), 2021 Aug 28;57(9).
PMID: 34577822 DOI: 10.3390/medicina57090899

Background and Objectives: Hip fractures constitute the most debilitating complication of osteoporosis with steadily increasing incidences in the aging population. Their intramedullary nailing can be challenging because of poor anchorage in the osteoporotic femoral head. Cement augmentation of Proximal Femoral Nail Antirotation (PFNA) blades demonstrated promising results by enhancing cut-out resistance in proximal femoral fractures. The aim of this study was to assess the impact of augmentation on the fixation strength of TFN-ADVANCEDTM Proximal Femoral Nailing System (TFNA) blades and screws within the femoral head and compare its effect when they are implanted in centre or anteroposterior off-centre position. Materials and Methods: Eight groups were formed out of 96 polyurethane low-density foam specimens simulating isolated femoral heads with poor bone quality. The specimens in each group were implanted with either non-augmented or cement-augmented TFNA blades or screws in centre or anteroposterior off-centre positions, 7 mm anterior or posterior. Mechanical testing was performed under progressively increasing cyclic loading until failure, in setup simulating an unstable pertrochanteric fracture with a lack of posteromedial support and load sharing at the fracture gap. Varus-valgus and head rotation angles were monitored. A varus collapse of 5° or 10° head rotation was defined as a clinically relevant failure. Results: Failure load (N) for specimens with augmented TFNA head elements (screw/blade centre: 3799 ± 326/3228 ± 478; screw/blade off-centre: 2680 ± 182/2591 ± 244) was significantly higher compared with respective non-augmented specimens (screw/blade centre: 1593 ± 120/1489 ± 41; screw/blade off-centre: 515 ± 73/1018 ± 48), p < 0.001. For both non-augmented and augmented specimens failure load in the centre position was significantly higher compared with the respective off-centre positions, regardless of the head element type, p < 0.001. Augmented off-centre TFNA head elements had significantly higher failure load compared with non-augmented centrally placed implants, p < 0.001. Conclusions: Cement augmentation clearly enhances the fixation stability of TFNA blades and screws. Non-augmented blades outperformed screws in the anteroposterior off-centre position. Positioning of TFNA blades in the femoral head is more forgiving than TFNA screws in terms of failure load.

Matched MeSH terms: Bone Screws

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