Anatomical considerations for the placement of cervical transarticular screws

2011 ◽  
Vol 14 (1) ◽  
pp. 114-121 ◽  
Author(s):  
Guanyi Liu ◽  
Rongming Xu ◽  
Weihu Ma ◽  
Shaohua Sun ◽  
Jianxiang Feng
Keyword(s):  
Ct Scan ◽  
Soft Tissues ◽  
Sagittal Plane ◽  
Axial Plane ◽  
Screw Placement ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Spinal Nerves ◽  
Starting Point ◽  
The Ideal

Object The object of this study was to determine the safe screw placement technique for cervical transarticular screw fixation. Methods Twenty cadaveric adult cervical spines were studied. All soft tissues surrounding the cervical spinal nerves from C-2 to T-1 were dissected carefully to expose the lateral mass, facet joint, transverse process, vertebral artery (VA), and spinal nerves (ventral and dorsal rami). After the proper entrance and exit points for the transarticular screws were determined, posterior transarticular screw implantation was performed under direct visualization from C2–3 to C5–6. A CT scan was performed to check the screw placement. The angle and length of the transarticular screw trajectory, the distance between the tip of the screw and the VA, and the sagittal safety angle were measured on the CT scan. Statistical analysis was performed using ANOVA (p < 0.05). Sagittal and axial orientations of transarticular screws were carefully analyzed. Results There was no nerve or artery impingement or penetration. The average caudal angle of the screws in the sagittal plane was 37.3° ± 5.0° and the lateral angle in the axial plane was 16.6° ± 4.6°. The average distance between the tip of the screw and the VA (the posterior border of the VA foramen) was 5.8 ± 1.5 mm. The average sagittal safety angle was 41.9° ± 5.6°. No difference was observed according to the vertebral level. The average bone purchase was 18.7 ± 1.4 mm. Bone purchase was significantly greater at C2–3 (23.2 ± 1.6 mm) than at C3–4 through C5–6 (17.2 ± 1.3 mm, p < 0.05). Conclusions This study establishes anatomical guidelines to allow for safe cervical transarticular screw insertion. The starting point of transarticular screws should be 1 mm medial to the midpoint of the lateral mass. The “ideal” drilling angle is approximately 37° in the inferior direction and 16° in the lateral direction for the C2–3 through the C5–6 levels. The screw should be directed as laterally as possible in the axial plane without causing the lateral mass to fracture and as caudally as the occipital bone permits in the sagittal plane. The ideal screw size would be 3.5 mm in diameter and 18 mm in length.

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.

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.

Accuracy and complications associated with the freehand C-1 lateral mass screw fixation technique: a radiographic and clinical assessment

2013 ◽  
Vol 18 (4) ◽  
pp. 372-377 ◽  
Author(s):  
Yong Hu ◽  
Christopher K. Kepler ◽  
Todd J. Albert ◽  
Zhen-shan Yuan ◽  
Wei-hu Ma ◽  
...  
Keyword(s):  
Spinal Canal ◽  
Ct Scanning ◽  
Ct Scans ◽  
Screw Placement ◽  
Type I ◽  
Type Ii ◽  
Lateral Mass ◽  
Type Iii ◽  
Clinical Records ◽  
The Ideal

Object The aims of this study were to evaluate a large series of posterior C-1 lateral mass screws (LMSs) to determine accuracy based on CT scanning findings and to assess the perioperative complication rate related to errant screw placement. Methods Accuracy of screw placement was evaluated using postoperative CT scans obtained in 196 patients with atlantoaxial instability. Radiographic analysis included measurement of preoperative and postoperative CT scans to evaluate relevant anatomy and classify accuracy of instrumentation placement. Screws were graded using the following definitions: Type I, screw threads completely within the bone (ideal); Type II, less than half the diameter of the screw violates the surrounding cortex (safe); and Type III, clear violation of transverse foramen or spinal canal (unacceptable). Results A total of 390 C-1 LMSs were placed, but 32 screws (8.2%) were excluded from accuracy measurements because of a lack of postoperative CT scans; patients in these cases were still included in the assessment of potential clinical complications based on clinical records. Of the 358 evaluable screws with postoperative CT scanning, 85.5% of screws (Type I) were rated as being in the ideal position, 11.7% of screws (Type II) were rated as occupying a safe position, and 10 screws (2.8%) were unacceptable (Type III). Overall, 97.2% of screws were rated Type I or II. Of the 10 screws that were unacceptable on postoperative CT scans, there were no known associated neurological or vertebral artery (VA) injuries. Seven unacceptable screws erred medially into the spinal canal, and 2 patients underwent revision surgery for medial screws. In 2 patients, unilateral C-1 LMSs penetrated the C-1 anterior cortex by approximately 4 mm. Neither patient with anterior C-1 penetration had evidence of internal carotid artery or hypoglossal nerve injury. Computed tomography scanning showed partial entry of C-1 LMSs into the VA foramen of C-1 in 10 cases; no occlusion, associated aneurysm, or fistula of the VA was found. Two patients complained of postoperative occipital neuralgia. This was transient in one patient and resolved by 2 months after surgery. The second patient developed persistent neuralgia, which remained 2 years after surgery, necessitating referral to the pain service. Conclusions The technique for freehand C-1 LMS fixation appears to be safe and effective without intraoperative fluoroscopy guidance. Preoperative planning and determination of the ideal screw insertion point, the ideal trajectory, and screw length are the most important considerations. In addition, fewer malpositioned screws were inserted as the study progressed, suggesting a learning curve to the technique.

SAFE ANGLE SCOPE FOR POSTERIOR ATLANTO-OCCIPITAL TRANSARTICULAR SCREW FIXATION

Neurosurgery ◽  
2009 ◽  
Vol 65 (3) ◽  
pp. 499-504 ◽  
Author(s):  
Wangjun Yan ◽  
Chengshi Zhang ◽  
Xuhui Zhou ◽  
Xiongsheng Chen ◽  
Wen Yuan ◽  
...  
Keyword(s):  
Sagittal Plane ◽  
Screw Fixation ◽  
Tomographic Reconstruction ◽  
Kirschner Wire ◽  
Screw Placement ◽  
X Rays ◽  
Transarticular Screw ◽  
Transarticular Screw Fixation ◽  
Computed Tomographic ◽  
Fresh Cadaver

Abstract OBJECTIVE To study the technical parameters related to, and explore the clinical significance of, posterior atlanto-occipital transarticular screw fixation. METHODS Posterior implantation of Kirschner wires via the atlanto-occipital joint was performed on 20 dry bone specimens with complete atlanto-occipital joints. The angle of the Kirschner wire was measured on a postimplantation x-ray. Three-dimensional computed tomographic reconstruction of the atlanto-occipital joint of 30 healthy adults was performed to measure the simulative safety range for screw placement in posterior atlanto-occipital transarticular screw fixation. The procedure was then conducted on 12 fresh cadaver occipitocervical specimens. X-rays and 3-dimensional computed tomographic reconstruction were performed postsurgery to verify exact screw positioning. RESULTS The ideal angles for screw placement were cephalocaudal angle in the sagittal plane of 53.3 ± 3.4 degrees, mediolateral angle in the coronal plane of 20.0 ± 2.6 degrees, a maximum allowable cephalocaudal angle of 74.6 ± 2.8 degrees (67.9–80.5 degrees), a minimum allowable cephalocaudal angle of 24.9 ± 1.9 degrees (22.1–29.4 degrees), a maximum allowable mediolateral angle of 40.5 ± 2.9 degrees (31.1–49.4 degrees), and a minimum allowable mediolateral angle of 0.7 ± 1.6 degrees (−4.1–5.9 degrees). Surgery simulation in the fresh cadaver specimens indicated that this safe scope is reliable. CONCLUSION There is a safe scope for the angle of the screw placement in posterior atlanto-occipital transarticular screw fixation. Posterior transarticular screw fixation can be safely performed for occipitocervical fusion fixation when utilizing careful screw placement.

Posterior C1 Stabilization Using Superior Lateral Mass as an Entry Point in a Case With Vertebral Artery Anomaly: Technical Case Report

2011 ◽  
Vol 68 (suppl_1) ◽  
pp. onsE246-onsE249 ◽  
Author(s):  
Jae Taek Hong ◽  
Woo Young Jang ◽  
Il Sup Kim ◽  
Seung Ho Yang ◽  
Jae Hoon Sung ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Vertebral Artery ◽  
Computed Tomography Angiography ◽  
Anatomical Variations ◽  
Entry Point ◽  
Screw Placement ◽  
Lateral Mass ◽  
Starting Point ◽  
Bursting Fracture ◽  
The Right

Abstract BACKGROUND AND IMPORTANCE: This is the first report of using the superior lateral mass as an alternative starting point for C1 posterior screw placement, demonstrating the importance of recognizing vertebral artery (VA) anomaly in deciding the surgical strategy for C1 screw placement. CLINICAL PRESENTATION: A 56-year-old man presented with severe neck pain after a fall. Imaging demonstrated an unstable bursting fracture at C4, C1-2 instability, and a subluxation at C2-3. Computed tomography angiography indicated that the persistent first intersegmental artery was located on the left side. The patient underwent anterior-posterior cervical fixation and fusion. Posterior C1 fixation was done with polyaxial screw rod construct using C1 superior lateral mass on the left side and C1 inferior lateral mass on the right side. The patient had no immediate postoperative deficits. At the 8-month follow-up examination, the patient was neurologically intact with a solid cervical fusion. CONCLUSION: The third segment of the VA is heterogeneous; therefore, preoperative radiologic studies should be performed to identify any anatomical variations. Using preoperative 3-dimensional computed tomography angiography, we can precisely identify an anomalous VA, thereby significantly reducing the risk of VA injury. To avoid significant morbidities associated with VA injury, a more optimal entry point for C1 fixation can be selected if a persistent first intersegmental artery or fenestrated VA is detected.

scholarly journals Posterior arch C-1 screw technique: a cadaveric comparison study

2017 ◽  
Vol 26 (6) ◽  
pp. 679-683 ◽  
Author(s):  
Marc Moisi ◽  
Christian Fisahn ◽  
Lara Tkachenko ◽  
Shiveindra Jeyamohan ◽  
Stephen Reintjes ◽  
...  
Keyword(s):  
Vertebral Artery ◽  
Nerve Root ◽  
Access Point ◽  
Screw Placement ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Entry Site ◽  
Starting Point ◽  
The Right

OBJECTIVEPosterior atlantoaxial stabilization and fusion using C-1 lateral mass screw fixation has become commonly used in the treatment of instability and for reconstructive indications since its introduction by Goel and Laheri in 1994 and modification by Harms in 2001. Placement of such lateral mass screws can be challenging because of the proximity to the spinal cord, vertebral artery, an extensive venous plexus, and the C-2 nerve root, which overlies the designated starting point on the posterior center of the lateral mass. An alternative posterior access point starting on the posterior arch of C-1 could provide a C-2 nerve root–sparing starting point for screw placement, with the potential benefit of greater directional control and simpler trajectory. The authors present a cadaveric study comparing an alternative strategy (i.e., a C-1 screw with a posterior arch starting point) to the conventional strategy (i.e., using the lower lateral mass entry site), specifically assessing the safety of screw placement to preserve the C-2 nerve root.METHODSFive US-trained spine fellows instrumented 17 fresh human cadaveric heads using the Goel/Harms C-1 lateral mass (GHLM) technique on the left and the posterior arch lateral mass (PALM) technique on the right, under fluoroscopic guidance. After screw placement, a CT scan was obtained on each specimen to assess for radiographic screw placement accuracy. Four faculty spine surgeons, blinded to the surgeon who instrumented the cadaver, independently graded the quality of screw placement using a modified Upendra classification.RESULTSOf the 17 specimens, the C-2 nerve root was anatomically impinged in 13 (76.5%) of the specimens. The GHLM technique was graded Type 1 or 2, which is considered “acceptable,” in 12 specimens (70.6%), and graded Type 3 or 4 (“unacceptable”) in 5 specimens (29.4%). In contrast, the PALM technique had 17 (100%) of 17 graded Type 1 or 2 (p = 0.015). There were no vertebral artery injuries found in either technique. All screw violations occurred in the medial direction.CONCLUSIONSThe PALM technique showed statistically fewer medial penetrations than the GHLM technique in this study. The reason for this is not clear, but may stem from a more angulated ”up-and-in” screw direction necessary with a lower starting point.

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>

Techniques and Tips for Freehand Placement of C7 Pedicle Screws With Respect to Cervicothoracic Constructs: 2-Dimensional Operative Video

2019 ◽  
Vol 18 (6) ◽  
pp. E234-E234 ◽  
Author(s):  
William Clifton ◽  
Steve Edwards ◽  
Christopher Louie ◽  
Conrad Dove ◽  
Aaron Damon ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Lateral Mass ◽  
Pedicle Screw Placement ◽  
Medial Border ◽  
Surgical Video ◽  
Starting Point ◽  
Patient Consent ◽  
Slight Displacement

Abstract We present a surgical video highlighting the technical pearls for C7 pedicle screw placement with respect to cervicothoracic constructs. Pedicle screw placement into C7 has been shown to enhance the biomechanical stability of both cervical and cervicothoracic constructs and is safe for patient related outcomes.1,2 Rod placement across the cervicothoracic junction is known to be difficult because of the variable starting point of the C7 pedicle screw, which may cause misalignment of the polyaxial heads with respect to the C7 and C6 screw heads. Using our step-wise method of anatomic screw placement, this potential pitfall is minimized. The T1 pedicle screw is placed first. The C6 lateral mass screw starting point is displaced slightly superiorly from the midpoint of the lateral mass in order to make room for the polyaxial head of the C7 pedicle screw. A small laminotomy is performed in order to find the medial border of the C7 pedicle. Palpation of the medial border allows for an approximation of the pedicle limits. The cranial-caudal angle of drilling is perpendicular to the C7 superior facet, and the medial-lateral trajectory typically falls between 15 and 20 degrees medial. Once the pedicle is cannulated, a ball-tipped probe is used to confirm intraosseous position. A rod is cut and contoured to the appropriate length of the construct. The C7 pedicle screw should capture the rod easily with slight displacement of the polyaxial head. Postinstrumentation anteroposterior and lateral fluoroscopy are performed to confirm good position of the lateral mass and pedicle screws. Patient consent was not required for this cadaveric surgical video.

Radiological and anatomical evaluation of the atlantoaxial transarticular screw fixation technique

1997 ◽  
Vol 86 (6) ◽  
pp. 961-968 ◽  
Author(s):  
Ali Abou Madawi ◽  
Adrian T. H. Casey ◽  
Guirish A. Solanki ◽  
Gerald Tuite ◽  
Robert Veres ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Screw Placement ◽  
Transoral Surgery ◽  
Spinal Instability ◽  
Lateral Mass ◽  
Transarticular Screw ◽  
Content Type ◽  
Posterior Surgery ◽  
Transarticular Screw Fixation ◽  
Fine Print

✓ Sixty-one patients treated with C1–2 transarticular screw fixation for spinal instability participated in a detailed clinical and radiological study to determine outcome and clarify potential hazards. The most common condition was rheumatoid arthritis (37 patients) followed by traumatic instability (15 patients). Twenty-one of these patients (onethird) underwent either surgical revision for a previously failed posterior fusion technique or a combined anteroposterior procedure. Eleven patients underwent transoral odontoidectomy and excision of the arch of C-1 prior to posterior surgery. No patient died, but there were five vertebral artery (VA) injuries and one temporary cranial nerve palsy. Screw malposition (14% of placements) was comparable to another large series reported by Grob, et al. There were five broken screws, and all were associated with incorrect placement. Anatomical measurements were made on 25 axis bones. In 20% the VA groove on one side was large enough to reduce the width of the C-2 pedicle, thus preventing the safe passage of a 3.5-mm diameter screw. In addition to the obvious dangers in patients with damaged or deficient atlantoaxial lateral mass, the following risk factors were identified in this series: 1) incomplete reduction prior to screw placement, accounting for two-thirds of screw complications and all five VA injuries; 2) previous transoral surgery with removal of the anterior tubercle or the arch of the atlas, thus obliterating an important fluoroscopic landmark; and 3) failure to appreciate the size of the VA in the axis pedicle and lateral mass. A low trajectory with screw placement below the atlas tubercle was found in patients with VA laceration. The technique that was associated with an 87% fusion rate requires detailed computerized tomography scanning prior to surgery, very careful attention to local anatomy, and nearly complete atlantoaxial reduction during surgery.

scholarly journals Sagittal and Axial Posterior Calcaneal Screw Prominence are Independent Risk Factors for Hardware Removal

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0037
Author(s):  
Alan Shamrock ◽  
Karthikeyan Chinnakkannu ◽  
Cameron Foreman ◽  
Natalie Glass ◽  
Annunziato Amendola ◽  
...  
Keyword(s):  
Risk Factor ◽  
Sagittal Plane ◽  
Weight Bearing ◽  
Axial Plane ◽  
Hardware Removal ◽  
Lateral Radiograph ◽  
Screw Head ◽  
Reconstructive Procedures ◽  
Starting Point ◽  
The Impact

Category: Hindfoot Introduction/Purpose: Painful hardware requiring removal occurs after the use of posterior calcaneal screws. Reconstructive procedures that rely on screws placed through the posterior calcaneus include calcaneal osteotomy and subtalar arthrodesis. Screw placement is typically percutaneous and relies on the use of fluoroscopy to evaluate screw starting point, length, and trajectory. Screw prominence in the sagittal plane is readily determined with a lateral radiograph, however screw location in the axial plane requires an intraoperative axial hindfoot view. The impact of screw prominence in the isolated axial plane on symptomatic hardware is unknown. The aim of this retrospective review is to determine, by analyzing postoperative radiographs, the association between posterior calcaneal screw type, sagittal and axial prominence, location, and trajectory with painful hardware requiring surgical removal. Methods: A consecutive series of 365 cases of posterior calcaneal screws in 333 patients (163 females: 48.9%) (mean age 47.4 years) was retrospectively reviewed from 2004-2018. Cases were performed by one of three fellowship trained foot and ankle surgeons. Inclusion criteria included the use of at least one posterior calcaneal screw and post-operative radiographs consisting of weight-bearing lateral and axial hindfoot views. Patient charts were retrospectively reviewed to determine the rate of symptomatic hardware removal (HWR). Weight-bearing radiographs were examined to determine screw head prominence in the lateral and axial planes, screw trajectory, and screw location in the calcaneus. Screw trajectory was calculated by subtracting the angle of the screw from the horizontal by the calcaneal pitch. Other variables collected included patient demographic information and screw number, diameter, and type. Statistical analysis was performed using Wilcoxon rank-sum and chi-square tests, with statistical significance defined as p<0.05. Results: The HWR rate was 16.7% (n=61). The HWR group was significantly younger (44 vs 48; p=0.0039) with more females (67.9% vs 45.4%; p=0.0026). Body mass index (BMI) (p=0.4167) and calcaneal pitch (p=0.7651) were not different between groups. Of screws that were flush or buried in the sagittal plane, 9.1% (n=64) were prominent on the hindfoot view. Screws flush/buried on both the lateral and hindfoot views (p<0.0001) were not associated with pain; prominent screws on the lateral radiograph (p=0.0002) and both the lateral and hindfoot radiographs (p=0.0071) were significantly more likely to undergo HWR. Isolated axial plane prominence of the plantar screw was found to be an independent risk factor for HWR (p=0.0060). Screw diameter (p=0.2318), location (p=0.4691) and trajectory (p=0.1077) were not associated with pain. Conclusion: Posterior calcaneal screws that were prominent on the lateral radiograph and both the lateral and hindfoot views were associated with HWR. Additionally, isolated prominence of the plantar screw on the hindfoot radiograph was a significant risk factor for hardware removal. These results emphasize the importance of not leaving screw heads proud. It is important to obtain and carefully analyzing the axial view in addition to a lateral view with intraoperative fluoroscopy. Relying on the lateral fluoroscopy view alone to assess screw head prominence is to be avoided. A weakness of this study is the lack of fluoroscopy images for comparison.

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