scholarly journals Establishing a New Bony Landmark for Safe Screw Insertion in Medial Displacement Calcaneal Osteotomy: A Simulation-Based Approach

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0029
Author(s):  
Jaeyoung Kim ◽  
Jonathan Day
Keyword(s):  
Sagittal Plane ◽  
Axial Plane ◽  
Osteotomy Site ◽  
Bony Landmark ◽  
Screw Insertion ◽  
Sinus Tarsi ◽  
Calcaneal Osteotomy ◽  
Bony Landmarks ◽  
Screw Length ◽  
Trajectory Angle

Category: Hindfoot; Other Introduction/Purpose: Medial displacement calcaneal osteotomy (MDCO) is a commonly performed procedure in flatfoot reconstruction. Fixation is often achieved with screws due to its ability to compress across the osteotomy site. Screws are placed via a free-handed technique without direct fluoroscopic visualization, due to difficulty attaining a simultaneous axial calcaneal view. In addition, the posterior calcaneal tuber translates medially after displacement, resulting in altered anatomical geometry. It is therefore important to establish a reliable external bony landmark when performing free-handed interfragmentary fixation in order to avoid potential screw-related complications and to provide better surgical technique and fixation. The purposes of this study are to validate a new external bony landmark and to establish the appropriate trajectory and screw length for free-hand screw fixation in MDCO. Methods: A total of 84 postoperative computed tomography (CT) scans of MDCO in 70 patients were analyzed. The images were reconstructed using a 3-dimensional simulation program (Vworks 4.0, Cybermed). Virtual screw insertion was simulated by aiming towards two bony landmarks: the base of the 5th metatarsal in the axial plane, and the sinus tarsi in the sagittal plane (Figure 1). A grading system was also utilized to classify scenarios in which the screw breached the distal cortical wall: Grade 1 was defined as contact between the virtual screw and the cortex, Grade 2 as the screw approaching the outer margin of the cortex, and Grade 3 as the screw penetrating the outer cortex. The trajectory angle between the screw and the osteotomy, as well as the screw size, were also measured. Results: The average age of patients was 24.5 (range, 19 to 53), and 100% were males. The average displacement of the posterior calcaneal fragment was 7.3+-1.5 mm (range, 3.9 to 13.8). Among the 84 virtual screws, only five (6.0%) breached the medial cortical wall of the osteotomized calcaneus. All medial breaches were Grade 1. None of the virtual screws breached the lateral cortical wall. Mean trajectory angle between the virtual screw and the osteotomy site was 74.9+-6.7˚ (range, 60.0 to 89.8˚). In the perioperative data, estimated maximum screw length by simulation was 55.6+-4.4 mm (range, 50 to 65). Conclusion: Our results suggest that the optimal trajectory of free-handed screw placement can be determined through simulation of calcaneal interfragmentary screw insertion using postoperative CT imaging. Using this simulation technology, we determined a trajectory towards the sinus tarsi on the sagittal plane and the base of the 5th metatarsal on the axial plane to be a reliable external bony landmark for placement of screws in MDCO. These promising results have potential implications in achieving better fixation as well as improving union rates and operative outcomes.

scholarly journals REPRODUCIBILITY OF S2-ALAR ILIAC SCREW MORPHOMETRIC ANALYSIS

2021 ◽  
Vol 29 (2) ◽  
pp. 97-100
Author(s):  
MARIANA DEMÉTRIO DE SOUSA PONTES ◽  
LUCAS AMÉRICO FRANCISCO ◽  
LUCAS KLAROSK ISMAEL ◽  
CARLOS FERNANDO PEREIRA DA SILVA HERRERO
Keyword(s):  
Morphometric Analysis ◽  
Sagittal Plane ◽  
Interobserver Reliability ◽  
Statistical Significance ◽  
Intraclass Correlation ◽  
Intraobserver Reliability ◽  
Axial Plane ◽  
Level Of Evidence ◽  
Screw Length ◽  
Trajectory Angle

ABSTRACT Objective: To evaluate the reproducibility of a S2-alar iliac (S2AI) screw parameters measurement method by inter and intraobserver reliability. Methods: Cross-sectional study, considering computed tomography exams. Morphometric analysis was performed by multiplanar reconstructions. Screw length, diameter and trajectory angles were the studied variables. To analyze the measurements reproducibility, intraclass correlation coefficient (ICC) was used. Results: Interobserver reliability was classified as strong for screw shortest length (ICC: 0.742) and diameter (ICC: 0.699). Interobserver reliability was classified as moderate for screw longest length (ICC: 0.553) and for screw trajectory angles in the axial plane for the longest (ICC: 0.478) and for the shortest lengths (ICC: 0.591). Intraobserver reliability was interpreted as excellent for screw shortest (ICC: 0.932) and longest lengths (ICC: 0.962) and diameter (ICC: 0.770) and screw trajectory angles in the axial plane for the screw longest (ICC: 0.773) and shortest lengths (ICC: 0.862). There were weak interobserver and strong intraobserver reliabilities for trajectory angle in sagittal plane, but no statistical significance was found. Conclusion: Inter and intraobserver reliability of S2AI screw morphometric parameters were interpreted from moderate to excellent in almost all studied variables, except for the screw trajectory angle in the sagittal plane measurement. Level of Evidence IV, Diagnostic Studies - Investigating a Diagnostic Test.

The morphology of proximal pole scaphoid fractures: implications for optimal screw placement

2017 ◽  
Vol 43 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Timothy J. Luchetti ◽  
Youssef Hedroug ◽  
John J. Fernandez ◽  
Mark S. Cohen ◽  
Robert W. Wysocki
Keyword(s):  
Sagittal Plane ◽  
Fracture Line ◽  
Screw Thread ◽  
Proximal Pole ◽  
Screw Insertion ◽  
Scaphoid Fractures ◽  
Starting Point ◽  
Screw Length ◽  
Sagittal Image ◽  
The Ideal

The purpose of this study was to measure the radiographic parameters of proximal pole scaphoid fractures, and calculate the ideal starting points and trajectories for antegrade screw insertion. Computed tomography scans of 19 consecutive patients with proximal pole fractures were studied using open source digital imaging and communications in medicine (DICOM) imaging measurement software. For scaphoid sagittal measurements, fracture inclination was measured with respect to the scaphoid axis. The ideal starting point for a screw in the proximal pole fragment was then identified on the scaphoid sagittal image that demonstrated the largest dimensions of the proximal pole, and hence the greatest screw thread purchase. Measurements were then taken for a standard screw trajectory in the axis of the scaphoid, and a trajectory that was perpendicular to the fracture line. The fracture inclination in the scaphoid sagittal plane was 25 (SD10) °, lying from proximal palmar to dorsal distal. The fracture inclination in the coronal plane was 9 (SD16) °, angling distal radial to proximal ulnar with reference to the coronal axis of the scaphoid. Using an ideal starting point that maximized the thread purchase in the proximal pole, we measured a maximum screw length of 20 (SD 2) mm when using a screw trajectory that was perpendicular to the fracture line. This was quite different from the same measurements taken in a trajectory in the axis of the scaphoid. We also identified a mean distance of approximately 10 mm from the dorsal fracture line to the ideal starting point. A precise understanding of this anatomy is critical when treating proximal pole scaphoid fractures surgically.

scholarly journals Radiographic parameters and a novel fluoroscopic control view for posterior screw fixation of coracoid base fractures

SICOT-J ◽  
2020 ◽  
Vol 6 ◽  
pp. 9
Author(s):  
Hatem Galal Said ◽  
Tarek Nabil Fetih ◽  
Hosam Elsayed Abd-Elzaher ◽  
Simon Martin Lambert
Keyword(s):  
Sagittal Plane ◽  
Coracoid Process ◽  
Entry Point ◽  
Coronal Plane ◽  
Screw Placement ◽  
Posterior Fixation ◽  
Screw Insertion ◽  
Screw Length ◽  
Scapular Spine ◽  
The Mean

Introduction: Coracoid fractures have the potential to lead to inadequate shoulder function. Most coracoid base fractures occur with scapular fractures and the posterior approaches would be utilized for surgical treatment. We investigated the possibility of fixing the coracoid through the same approach without an additional anterior approach. Materials and methods: Multi-slice CT scans of 30 shoulders were examined and the following measurements were performed by an independent specialized radiologist: posterior coracoid screw entry point measured form infraglenoid tubercle, screw trajectory in coronal plane in relation to scapular spine and lateral scapular border, screw trajectory in sagittal plane in relation to glenoid face bisector line and screw length. We used the results from the CT study to guide postero-anterior coracoid screw insertion under fluoroscopic guidance on two fresh frozen cadaveric specimens to assess the reproducibility of accurate screw placement based on these parameters. We also developed a novel fluoroscopic projection, the anteroposterior (AP) coracoid view, to guide screw placement in the para-coronal plane. Results: The mean distance between entry point and the infraglenoid tubercle was 10.8 mm (range: 9.2–13.9, SD 1.36). The mean screw length was 52 mm (range: 46.7–58.5, SD 3.3). The mean sagittal inclination angle between was 44.7 degrees (range: 25–59, SD 5.8). The mean angle between screw line and lateral scapular border was 47.9 degrees (range: 34–58, SD 4.3). The mean angle between screw line and scapular spine was 86.2 degrees (range: 75–95, SD 4.9). It was easy to reproduce the screw trajectory in the para-coronal plane; however, multiple attempts were needed to reach the correct angle in the parasagittal plane, requiring several C-arm corrections. Conclusion: This study facilitates posterior fixation of coracoid process fractures and will inform the “virtual visualization” of coracoid process orientation.

scholarly journals Optimal ilio-sacral screw trajectory in paediatric patients : a computed tomography study

2021 ◽  
Vol 87 (2) ◽  
pp. 285-291
Author(s):  
Mathilde Gaume ◽  
Mohamed Amine Triki ◽  
Christophe Glorion ◽  
Sylvain Breton ◽  
Lofti Miladi
Keyword(s):  
Computed Tomography ◽  
Spinal Canal ◽  
Sagittal Plane ◽  
Optimal Angle ◽  
Pelvic Fixation ◽  
Screw Insertion ◽  
Insertion Angle ◽  
Paediatric Patients ◽  
Screw Length ◽  
Screw Insertion Angle

Pelvic fixation during procedures performed to treat spinal deformities in paediatric patients remains challenging. No computed tomography studies in paediatric have assessed the optimal trajectory of ilio- sacral screws to prevent screw malposition. We used pelvic computed tomography from 80 children divided into four groups : females <10 and ≥10 years and males <10 and ≥10 years. A secure triangular corridor parallel to the upper S1 endplate was delineated based on three fixed landmarks. The optimal screw insertion angle was subtended by the horizontal and the line bisecting the secure corridor. Student’s t test was applied to determine whether the optimal screw insertion angle and/or anatomical parameters were associated with age and/or sex. Mean optimal angle was 32.3°±3.6°, 33.8°±4.7°, 30.2°±5.0°, and 30.4°±4.7° in the younger females, younger males, older females, and older males, respectively. The mean optimal angle differed between the two age groups (p=0.004) but not between females and males (p=0.55). Optimal mean screw length was 73.4±9.9 mm. Anatomical spinal canal parameters in the transverse plane varied with age (p=0.02) and with sex in the older children (p=0.008), and those in the sagittal plane varied with sex (p=0.04). Age affected ilio-sacral screw positioning, whereas sex did not. Several anatomical spinal canal parameters varied with age and sex. These results should help to ensure safe and easy ilio-sacral screw placement within a secure corridor.

scholarly journals Surgical Morphometry of C1 and C2 Vertebrae: A Three-Dimensional Computed Tomography Analysis of 180 Chinese, Indian, and Malay Patients

2017 ◽  
Vol 11 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Chee Kean Lee ◽  
Tiam Siong Tan ◽  
Chris Yin Wei Chan ◽  
Mun Keong Kwan
Keyword(s):  
Computed Tomography ◽  
Sagittal Plane ◽  
Imaging Study ◽  
Asian Population ◽  
Safe Zone ◽  
Simulation Software ◽  
Axial Plane ◽  
Lateral Mass ◽  
Screw Length ◽  
Tomography Analysis

<sec><title>Study Design</title><p>Clinical imaging study.</p></sec><sec><title>Purpose</title><p>To study the surgical morphometry of C1 and C2 vertebrae in Chinese, Indian, and Malay patients.</p></sec><sec><title>Overview of Literature</title><p>C1 lateral mass and C2 pedicle screw fixation is gaining popularity. However, there is a lack of C1–C2 morphometric data for the Asian population.</p></sec><sec><title>Methods</title><p>Computed tomography analysis of 180 subjects (60 subjects each belonging to Chinese, Indian, and Malay populations) using simulation software was performed. Length and angulations of C1 lateral mass (C1LM) and C2 pedicle (C2P) screws were assessed.</p></sec><sec><title>Results</title><p>The predicted C1LM screw length was between 23.2 and 30.2 mm. The safe zone of trajectories was within 11.0°±7.7° laterally to 29.1°±6.2° medially in the axial plane and 37.0°±10.2° caudally to 20.9°±7.8° cephalically in the sagittal plane. The shortest and longest predicted C2P screw lengths were 22.1±2.8 mm and 28.5±3.2 mm, respectively. The safe trajectories were from 25.1° to 39.3° medially in the axial plane and 32.3° to 45.9° cephalically in the sagittal plane.</p></sec><sec><title>Conclusions</title><p>C1LM screw length was 23–30 mm with the axial safe zone from 11° laterally to 29° medially and sagittal safe zone at 21° cephalically. C2P screw length was 22–28 mm with axial safe zone from 26° to 40° medially and sagittal safe zone from 32° to 46° cephalically. These data serve as an important reference for Chinese, Indian, and Malay populations during C1–C2 instrumentation.</p></sec>

Factors affecting lateral mass screw placement at C-7

2011 ◽  
Vol 14 (3) ◽  
pp. 405-411 ◽  
Author(s):  
Kalil G. Abdullah ◽  
Amy S. Nowacki ◽  
Michael P. Steinmetz ◽  
Jeffrey C. Wang ◽  
Thomas E. Mroz
Keyword(s):  
Sagittal Plane ◽  
Anatomical Variation ◽  
Axial Plane ◽  
Screw Placement ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Modified Technique ◽  
Modified Method ◽  
Starting Point ◽  
Lateral Mass Screws

Object The C-7 lateral mass has been considered difficult to fit with instrumentation because of its unique anatomy. Of the methods that exist for placing lateral mass screws, none particularly accommodates this anatomical variation. The authors have related 12 distinct morphological measures of the C-7 lateral mass to the ability to place a lateral mass screw using the Magerl, Roy-Camille, and a modified Roy-Camille method. Methods Using CT scans, the authors performed virtual screw placement of lateral mass screws at the C-7 level in 25 male and 25 female patients. Complications recorded included foraminal and articular process violations, inability to achieve bony purchase, and inability to place a screw longer than 6 mm. Violations were monitored in the coronal, axial, and sagittal planes. The Roy-Camille technique was applied starting directly in the middle of the lateral mass, as defined by Pait's quadrants, with an axial angle of 15° lateral and a sagittal angle of 90°. The Magerl technique was performed by starting in the inferior portion of the top right square of Pait's quadrants and angling 25° laterally in the axial plane with a 45° cephalad angle in the sagittal plane. In a modified method, the starting point is similar to the Magerl technique in the top right square of Pait's quadrant and then angling 15° laterally in the axial plane. In the sagittal plane, a 90° angle is taken perpendicular to the dorsal portion of the lateral mass, as in the traditional Roy-Camille technique. Results Of all the morphological methods analyzed, only a combined measure of intrusion of the T-1 facet and the overall length of the C-7 lateral mass was statistically associated with screw placement, and only in the Roy-Camille technique. Use of the Magerl technique allowed screw placement in 28 patients; use of the Roy-Camille technique allowed placement in 24 patients; and use of the modified technique allowed placement in 46 patients. No screw placement by any method was possible in 4 patients. Conclusions There is only one distinct anatomical ratio that was shown to affect lateral mass screw placement at C-7. This ratio incorporates the overall length of the lateral mass and the amount of space occupied by the T-1 facet at C-7. Based on this virtual study, a modified Roy-Camille technique that utilizes a higher starting point may decrease the complication rate at C-7 by avoiding placement of the lateral mass screw into the T1 facet.

Depth of vertebral screw insertion using a cortical bone trajectory technique in lumbar spinal fusion: radiological significance of a long cortical bone trajectory

2021 ◽  
pp. 1-6
Author(s):  
Keitaro Matsukawa ◽  
Yoshihide Yanai ◽  
Kanehiro Fujiyoshi ◽  
Takashi Kato ◽  
Yoshiyuki Yato
Keyword(s):  
Cortical Bone ◽  
Vertebral Body ◽  
Screw Loosening ◽  
Lumbar Spinal Fusion ◽  
Insertion Depth ◽  
Cortical Bone Trajectory ◽  
Screw Insertion ◽  
Bone Fusion ◽  
Screw Length ◽  
Lumbar Spinal

OBJECTIVE Contrary to original cortical bone trajectory (CBT), “long CBT” directed more anteriorly in the vertebral body has recently been recommended because of improved screw fixation and load sharing within the vertebra. However, to the authors’ knowledge there has been no report on the clinical significance of the screw length and screw insertion depth used with the long CBT technique. The aim of the present study was to investigate the influence of the screw insertion depth in the vertebra on lumbar spinal fusion using the CBT technique. METHODS A total of 101 consecutive patients with L4 degenerative spondylolisthesis who underwent single-level posterior lumbar interbody fusion at L4–5 using the CBT technique were included (mean follow-up 32.9 months). Screw loosening and bone fusion were radiologically assessed to clarify the factors contributing to these outcomes. Investigated factors were as follows: 1) age, 2) sex, 3) body mass index, 4) bone mineral density, 5) intervertebral mobility, 6) screw diameter, 7) screw length, 8) depth of the screw in the vertebral body (%depth), 9) facetectomy, 10) crosslink connector, and 11) cage material. RESULTS The incidence of screw loosening was 3.1% and bone fusion was achieved in 91.7% of patients. There was no significant factor affecting screw loosening. The %depth in the group with bone fusion [fusion (+)] was significantly higher than that in the group without bone fusion [fusion (−)] (50.3% ± 8.2% vs 37.0% ± 9.5%, respectively; p = 0.001), and multivariate logistic regression analysis revealed that %depth was a significant independent predictor of bone fusion. Receiver operating characteristic curve analysis identified %depth > 39.2% as a predictor of bone fusion (sensitivity 90.9%, specificity 75.0%). CONCLUSIONS This study is, to the authors’ knowledge, the first to investigate the significance of the screw insertion depth using the CBT technique. The cutoff value of the screw insertion depth in the vertebral body for achieving bone fusion was 39.2%.

scholarly journals P.141 Is occipito-condylar screw a better alternative fixation point for occipitocervical stabilization? 1. Review of the literature

2018 ◽  
Vol 45 (s2) ◽  
pp. S53-S54
Author(s):  
Ns Alshafai ◽  
M Dibenedetto
Keyword(s):  
Surgical Techniques ◽  
Biomechanical Properties ◽  
Occipital Condyle ◽  
Occipitocervical Fusion ◽  
Anatomical Structures ◽  
Screw Insertion ◽  
Screw Length ◽  
Entry Points ◽  
Alternative Fixation ◽  
Fixation Points

Background: Occipitocervical fusion (OCF) using screws and rods offers immediate stability and an high fusion rates. However, multiple cranial fixation points are required in order to compensate for the poor bony purchase. Methods: The aim of this study was to compare the occipital condyle screw with the standard OCF techniques as well as to compare available techniques of the occipital condyle screw insertion. Materials and Methods: A comprehensive “Medline” and “Web of science” database search was performed. Cadaveric, radiographic and case studies were included. Results: The occipital condyle screw in comparison to the occipital plate enables an increased screw length, greater screw pullout strength, lower profile of the hardware and extended grafting surface. Both constructs have similar biomechanical properties (range of motion restriction, stiffness). Proximity of the vertebral artery and hypoglossal canal presents the greatest technical challenge of occipital condyle screw. Four surgical techniques with different entry points, cranial-caudal and medial angulations were described. None of these techniques is superior to the other. Conclusions: Occipital condyle screw is a viable alternative to standard OCF techniques. Challenges exist due to the proximity of the vital anatomical structures. Choice between four available techniques depends on unique patient’s anatomy

scholarly journals Safe Zone for Percutaneous Screw Fixation - Talonavicular Fusion

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0043
Author(s):  
Ashish Shah ◽  
Sung Lee ◽  
Sameer Naranje ◽  
Zachariah Pinter ◽  
Robert Stibolt ◽  
...  
Keyword(s):  
Medial Branch ◽  
Screw Insertion ◽  
Anterior Branch ◽  
Bony Landmarks ◽  
Medial Plane ◽  
Extensor Hallucis Longus ◽  
Hindfoot Deformities ◽  
Fresh Frozen ◽  
Optimal Fusion ◽  
Neurovascular Structures

Category: Hindfoot Introduction/Purpose: Talonavicular fusion has been established as a reliable intervention for degenerative, inflammatory, and traumatic joint lesions as well as hindfoot deformities. In order to achieve optimal fusion, various versions of the procedure have been introduced in literature and have remained a topic of contention, with the most common variation involving the insertion of 1 to 3 screws dorsomedially and dorsolaterally. Dorsolateral screw placements commonly cause neurovasculature injury. The purpose of our cadaveric study was first to establish the safety of the dorsolateral percutaneous screw insertion in relation to these dorsal neurovascular structures, and then subsequently to standardize the ideal placement of the dorsolateral screw by comparing two insertion sites based on consistent bony landmarks. Methods: Ten fresh-frozen cadaver legs amputated at the knee were used for this study. Percutaneous cannulated screws were inserted to perform isolated talonavicular arthrodesis. The screws were inserted at 3 consistent sites: “medial screw” at dorsomedial navicular where it intersected at the medial plane of the first cuneiform, “central screw” at the edge of dorsal navicular between medial and intermediate cuneiforms, and “lateral screw” at the edge of dorsal navicular between intermediate and lateral cuneiforms. Superficial and deep dissections were carried out to identify any injured nerves, arteries, and tendons. Results: The mean age at death in our sample of cadavers was 80.1 ± 7.5 years (range 68 to 92) and had the BMI of 21.8 ± 2.4 (range 18.1 to 25.1). There were 5 males (50.0%) and 5 females (50.0%). The medial screw injured the anterior tibialis tendon in 2 cases (20.0%), the central screw injured the extensor hallucis longus tendon in 3 cases (30.0%), and the lateral screw injured the anterior branch of SPN, lateral branch of SPN, and medial branch of DPN once each in a total of 3 cases (30.0%). Conclusion: TN fusion with central screw placement at the interspace between the medial and intermediate cuneiforms protects the neurovasculatures of the foot to a superior extent than lateral screws between the intermediate and lateral cuneiforms.

scholarly journals Three-Dimensional Displacement after a Medializing Calcaneal Osteotomy in Relation to the Hindfoot Alignment and Osteotomy Angle

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0006
Author(s):  
Matthias Peiffer ◽  
C. Belvedere ◽  
S. Clockaerts ◽  
T. Leenders ◽  
Alexej Barg ◽  
...  
Keyword(s):  
Weight Bearing ◽  
Three Dimensional ◽  
Valgus Deformity ◽  
Flat Foot ◽  
Hindfoot Alignment ◽  
Calcaneal Osteotomy ◽  
Bony Landmarks ◽  
Operative Planning ◽  
Osteotomy Plane ◽  
Computer Based

Category: Hindfoot Introduction/Purpose: An adult-acquired flatfoot deformity is a three-dimensional (3D) condition characterized by a loss of the medial longitudinal arch, valgus alignment of the hindfoot, and abduction of the midfoot. When conservative measures are not sufficient, a medializing calcaneal osteotomy (MCO) is frequently performed to correct the deformity, but there is lack of data on the associated three-dimensional variables defining the final correction. A possible reason for this shortcoming could be the current image-based analyses, mainly performed on bi-dimensional radiographs. These are hampered by errors in 3D rotations and superimposition of bony structures. The aim of this study was therefore to assess the correlation between the preoperative hindfoot valgus deformity and calcaneal osteotomy angle and the postoperative calcaneal displacement by use of weightbearing CT (WBCT). Methods: Weight-bearing CT scans obtained pre- and post-operatively were analyzed for sixteen patients with a mean age of 49.4 years (range: 18-66 years). Indication for surgery was adult-acquired flat foot deformity stage II. Based on the WBCT images, pre- and post-operative 3D bone morphological models of the tibia, talus, calcaneus, and the second metatarsal were created, on which anatomical bony landmarks were computationally identified to define a Foot Anatomical reference Frame (FAF). This FAF was used to measure valgus deformity pre- and post-operatively, inclination of the osteotomy plane, and displacement of the calcaneus (Fig. 1). Linear regression was conducted to assess the relationship between these measurements. Results: On average, the hindfoot valgus changed from 13.1° (±4.6) preoperatively to 5.7° (±4.3) postoperatively. A mean inferior displacement of 3.2 mm (±1.3) was observed along the osteotomy with a mean inclination angle of 54.6° (±5.6), 80.5° (±10.7), - 13.7° (±15.7) in the axial, sagittal and coronal planes, respectively. A statistically significant positive relationship (P < .05, R2 = 0.6) was found between the preoperative valgus, the axial osteotomy inclination, and the inferior displacement. Conclusion: This study shows that the degree of preoperative valgus of the hindfoot and the axial osteotomy angle are predictive factors for the amount of postoperative plantar displacement of the calcaneus. These findings contrast the general recommendation of performing a 90° calcaneal osteotomy angle, i.e. perpendicular to the lateral calcaneal wall in every patient. The obtained factors should be taken into account when performing a MCO and could be integrated in a computer-based pre- operative planning.

Sign in / Sign up

Export Citation Format

Share Document