scholarly journals A practical ‘safe zone’ technique for lag screw fixation of the fibula

2018 ◽  
Vol 100 (5) ◽  
pp. 409-412 ◽  
Author(s):  
AR Kaye ◽  
W Marlow ◽  
G Williams ◽  
AP Molloy ◽  
LW Mason
Keyword(s):  
At Risk ◽  
Magnetic Resonance ◽  
Achilles Tendon ◽  
Ankle Joint ◽  
Safe Zone ◽  
Magnetic Resonance Images ◽  
Exit Point ◽  
Simple Method ◽  
Lag Screw ◽  
Medial Edge

Introduction During ankle fracture fixation, iatrogenic trauma to retro fibula structures can result in morbidity and reoperation. We describe a safe zone for lag screw insertion. Materials and methods This study was completed in three sections. We identified the average entry and exit points for the lag screw using 45 Weber B ankle fractures identified from our trauma database. We then analysed 26 sequentially presented ankle magnetic resonance images, concentrating on axial sections at 4, 8, 12 and 16 mm above the ankle joint. Finally, we used 63 sequentially performed magnetic resonance scans to confirm the safe zone from these consistent structures. Results The typical lag screw exit point was 14.2 mm above the ankle joint (95% confidence Interval 11.3–17.1 mm). A safe zone trajectory occurred between 31 and 45 degrees taken from the anterior aspect of the flat fibular surface at this level. The obvious palpable landmark to direct screw trajectory and avoid ‘at risk’ structures was found to be the medial edge of the Achilles tendon. Our final dataset confirmed in 63 scans, the medial aspect of the Achilles tendon to be a consistent safe zone with a minimum distance of at risk structures of 4 mm. Conclusion This simple method of directing the fibula lag screw towards the palpable medial edge of the Achilles tendon is practical, easy to teach and directs the screw on a safe trajectory away from the most commonly injured structures around the back of the fibula.

scholarly journals Safe Zone for Insertion of a Fibular Lag Screw in Ankle Fracture Fixation

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0033
Author(s):  
Lyndon Mason ◽  
Angus Kaye ◽  
William Marlow ◽  
Geraint Williams ◽  
Andrew Molloy
Keyword(s):  
Achilles Tendon ◽  
Fracture Fixation ◽  
Ankle Fracture ◽  
Flat Surface ◽  
Safe Zone ◽  
Screw Placement ◽  
Exit Point ◽  
Lag Screw ◽  
Anterior Aspect ◽  
Mri Scans

Category: Ankle Introduction/Purpose: Fibular lag screw placement during ankle fracture fixation is not without risk. The screw placement endangers either the tendons of the peronei or the posterior rim of the incisura if misplaced. Our aim was to identify a predictable safe zone for screw placement. Methods: 45 radiographs of Weber B fractures were reviewed to determine the typical height of lag screw entry and exit points. 63 MRI scans of anatomically normal ankles were reviewed to evaluate tendon position and syndesmosis location. The safe zone could then be determined using composite images. Results: On review of the 45 ankle fracture radiographs; the typical lag screw exit point was found to be 14.2 mm above the ankle joint (95% Confidence Interval: 11.3-17.1 mm). Using the composite MRI images, there was a consistent flat anterior aspect of the fibula at this level. A safe zone trajectory was seen to occur between 31 and 45 degrees taken from the anterior aspect of the flat fibular surface at this level. The minimum distance to at-risk structures using this trajectory was 4 mm. If this consistent entry point is used, the MRI scans demonstrated that if the drill was aimed towards the medial edge of the Achilles tendon, the correct trajectory would be performed. Conclusion: The flat surface of the fibula is a constant landmark on MRI and is visible during surgery. The peroneal tendons and posterior rim of the incisura have a constant predictable position related to this. The safe zone for insertion of a lag screw is between 31 and 45 degrees medial to the anterior aspect of this flat surface. This represents aiming the drill towards the medial aspect of the Achilles tendon.

scholarly journals Ankle morphology amplifies calcaneus movement relative to triceps surae muscle shortening

2013 ◽  
Vol 115 (4) ◽  
pp. 468-473 ◽  
Author(s):  
R. Csapo ◽  
J. Hodgson ◽  
R. Kinugasa ◽  
V. R. Edgerton ◽  
S. Sinha
Keyword(s):  
Magnetic Resonance ◽  
Achilles Tendon ◽  
Ankle Joint ◽  
Sagittal Plane ◽  
Triceps Surae ◽  
Myotendinous Junction ◽  
Joint Movement ◽  
Center Of Rotation ◽  
Moment Arms ◽  
Plantarflexor Muscles

The present study investigated the mechanical role of the dorsoventral curvature of the Achilles tendon in the conversion of the shortening of the plantarflexor muscles into ankle joint rotation. Dynamic, sagittal-plane magnetic resonance spin-tagged images of the ankle joint were acquired in six healthy subjects during both passive and active plantarflexion movements driven by a magnetic resonance compatible servomotor-controlled foot-pedal device. Several points on these images were tracked to determine the 1) path and deformation of the Achilles tendon, 2) ankle's center of rotation, and 3) tendon moment arms. The degree of mechanical amplification of joint movement was calculated as the ratio of the displacements of the calcaneus and myotendinous junction. In plantarflexion, significant deflection of the Achilles tendon was evident in both the passive (165.7 ± 7.4°; 180° representing a straight tendon) and active trials (166.9 ± 8.8°). This bend in the dorsoventral direction acts to move the Achilles tendon closer to the ankle's center of rotation, resulting in an ∼5% reduction of moment arm length. Over the entire range of movement, the overall displacement of the calcaneus exceeded the displacement of the myotendinous junction by ∼37%, with the mechanical gains being smaller in dorsi- and larger in plantarflexed joint positions. This is the first study to assess noninvasively and in vivo using MRI the curvature of the Achilles tendon during both passive and active plantarflexion movements. The dorsoventral tendon curvature amplifies the shortening of the plantarflexor muscles, resulting in a greater displacement of the tendon's insertion into the calcaneus compared with its origin.

scholarly journals Xanthoma Combined With Gout Infiltration of the Achilles Tendon: A Case Report

2019 ◽  
Vol 12 ◽  
pp. 117954411986526
Author(s):  
Yuan Fu ◽  
Qiu-Li Huang
Keyword(s):  
Uric Acid ◽  
Case Report ◽  
Magnetic Resonance ◽  
Achilles Tendon ◽  
Rare Condition ◽  
Magnetic Resonance Images ◽  
Purine Metabolism ◽  
Acid Excretion ◽  
Uric Acid Excretion

Xanthoma is a rare condition mostly caused by hyperlipidemia. The pathogenesis of gout is hyperuricemia, which is caused by a disorder of purine metabolism and/or a decrease in uric acid excretion. Xanthoma combined with gout is very rare. This case report presents magnetic resonance images of a case of xanthoma combined with gout infiltration of the Achilles tendon.

“Snake Sign” Secondary Sign of Achilles Tendon Rupture

2019 ◽  
Vol 1 ◽  
pp. 79-81
Author(s):  
Aamer Iqbal ◽  
Hiten Panchal ◽  
Ramanan Rajakulasingam ◽  
Amit Shah ◽  
Vemuri Varaprasad ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Achilles Tendon ◽  
Tendon Rupture ◽  
Achilles Tendon Rupture ◽  
Plantar Fascia ◽  
Magnetic Resonance Images ◽  
Full Thickness ◽  
Secondary Signs

Objective: We describe a secondary sign (Snake sign) due to lax plantar fascia in full-thickness rupture of Achilles tendon. Materials and Methods: A 100 consecutive magnetic resonance images with intact Achilles tendon and second group of 17 patients with Achilles tendon rupture (ATR) were analyzed for Snake sign and angle between the achilles tendon and plantar fascia (APA) was calculated. Results: Significant decrease in the APA (P < 0.0001) with ATR and Snake sign was present in 8 of the 17 cases in the second cohort. Conclusion: Snake sign and APA are useful secondary signs for ATR.

An emerging technology: Nuclear magnetic resonance microscopy

1988 ◽  
Vol 46 ◽  
pp. 1000-1001
Author(s):  
M.J. Hennessy ◽  
E. Kwok
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Basic Research ◽  
Local Environment ◽  
Magnetic Resonance Images ◽  
Nmr Microscopy ◽  
Mri Scans ◽  
Temperature Relaxation ◽  
Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

Functional information from magnetic resonance imaging

1995 ◽  
Vol 53 ◽  
pp. 84-85
Author(s):  
Alan P. Koretsky ◽  
Afonso Costa e Silva ◽  
Yi-Jen Lin
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Cancer Biology ◽  
Imaging Modality ◽  
Magnetic Resonance Images ◽  
Great Success ◽  
Functional Information ◽  
Resonance Imaging ◽  
High Resolution Mri

Magnetic resonance imaging (MRI) has become established as an important imaging modality for the clinical management of disease. This is primarily due to the great tissue contrast inherent in magnetic resonance images of normal and diseased organs. Due to the wide availability of high field magnets and the ability to generate large and rapidly switched magnetic field gradients there is growing interest in applying high resolution MRI to obtain microscopic information. This symposium on MRI microscopy highlights new developments that are leading to increased resolution. The application of high resolution MRI to significant problems in developmental biology and cancer biology will illustrate the potential of these techniques.In combination with a growing interest in obtaining high resolution MRI there is also a growing interest in obtaining functional information from MRI. The great success of MRI in clinical applications is due to the inherent contrast obtained from different tissues leading to anatomical information.

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