Injury, Int. J. Care Injured 45 (2014) 1867–1869
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
Clavicular caution: An anatomic study of neurovascular structures Luke Robinson a,*, Federico Persico b, Eric Lorenz c, David Seligson d a
Department of Orthopaedic Surgery, University of Louisville School of Medicine, Louisville, KY, USA Orthopaedic Surgery, Fundacion Valle del Lili, Cali, Colombia c Greifswald University, Greifswald, Germany d Department of Orthopaedic Surgery, University of Louisville, Louisville, KY, USA b
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 11 August 2014
Open reduction and internal fixation of the clavicle is used to treat displaced fractures of the midshaft of the clavicle. Complications of operative intervention include injuries to major neurovascular structures including the subclavian artery and vein. Unlike other surgical approaches, palpation or visualization of the deep neurovascular structures at risk is rarely performed and is not part of the routine approach. This study aims to further elucidate the relationship of major neurovascular structures in the shoulder to the clavicle using sectioned fresh frozen cadaveric specimens. Using five cadaveric specimens, sagittal sections were performed using a band saw. Sections were taken every 15 mm. Using these sections, structures were identified and photos were taken using a standardized approach to allow for precise and accurate measurements. Measurements taken included the distance from the nearest clavicular cortex to the centre of the subclavian artery, vein, and brachial plexus. These measurements were taken from five limbs on five different cadavers. Our results were consistent with previous studies. Medially, the subclavian vein was intimately related medially (4.8 mm) to the clavicle, whereas the artery and brachial plexus were both >2 cm from the clavicle. At about the junction of the middle and second-thirds of the clavicle, all three structures were within 2 cm of the clavicle. Moving laterally, these structures moved further away and at the acromioclavicular (AC) joint were at least 4.5 cm away from the clavicle on average. This study reiterates that the medial third of the clavicle is closely associated with neurovascular structures and that care should be taken here when using drills, depth gauges, and clamps. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Clavicle fracture Clavicle anatomy Clavicle nonunion Clavicle ORIF Complication
Introduction Clavicle fractures comprise around 3% of all fractures in adults and about 80% involve the midshaft [1–3]. While most can be treated nonoperatively with good outcomes [4,5], recent studies have suggested that the surgical treatment of displaced midshaft clavicle fractures may improve functional outcomes and prevent symptomatic nonunion [6,7]. Open reduction and internal fixation (ORIF) of these fractures provides stable anatomic reduction that restores length and prevents symptomatic malunion [8]. However, injuries to the nearby neurovascular structures have been reported as a result of surgical intervention [9–11]. Previous studies have reported on anatomic relationships between the clavicle and the surrounding neurovascular structures.
* Corresponding author. Tel.: +1 859 852 5319; fax: +1 502 852 7227. E-mail addresses: [email protected] (L. Robinson), [email protected] (F. Persico), [email protected] (E. Lorenz). http://dx.doi.org/10.1016/j.injury.2014.08.031 0020–1383/ß 2014 Elsevier Ltd. All rights reserved.
Werner and Reed reported on screw tip contact during simulated ORIF of the middle third clavicle fractures using fresh cadaver specimens based on the plate position both superiorly and anteroinferiorly. They reported no difference in screw tip contact based on the plate position and recommended plating the clavicle with the arm abducted to increase the distance of these structures from the bone [12]. Other studies have taken a more purely anatomic approach. Lo and Eastman reported on the locations of vital structures in fresh cadaveric specimens. Their results suggested that anteroinferior instrumentation on the medial third of the clavicle should be performed with caution due to the proximity of the subclavian artery 15–22 mm from the posterior aspect of the clavicle [13]. Radiological studies have also examined the relationships of neurovascular structures to the clavicle. Using three-dimensional (3D) computed tomographic (CT) arteriograms, one study aimed to describe safe zones for drilling during plating of clavicular fractures. They reported that the subclavian vein is intimately related to the clavicle medially where it was found on average 4.77 mm
L. Robinson et al. / Injury, Int. J. Care Injured 45 (2014) 1867–1869
1868
Table 1 Average measurements of five cadaveric specimens. Measurements taken from photographs. Distances represent the closest distance in millimetres between the clavicle cortex and the vessel or nerve edge. Section number (medial to lateral)
Subclavian artery (mm)
Subclavian vein (mm)
Brachial plexus (mm)
1 2 3 4 5 6 7 8
23.4 3.8 21.5 4.0 18.6 4.8 21.8 9.1 28.5 13.5 35.3 15.2 42.3 16.8 53.1 17.1
4.8 2.6 6.6 4.0 14.1 6.5 20.7 13.1 28.9 18.8 42.8 20.7 52.0 22.3 67.2 20.3
33.4 6.4 25.0 5.2 15.9 4.2 15.2 4.6 21.2 12.3 30.3 13.6 37.8 14.2 48.3 15.3
posteriorly. They also reported that the artery was at a safer 25 mm posterior to the clavicle and that moving laterally the structures were found more posterioinferiorly and were located further from the clavicle [14]. In a separate study using magnetic resonance imaging (MRI), safe drilling angles and depths in the medial half of the clavicle were determined based on parasagittal images. The authors concluded that the drilling depth should be limited to 17 mm to avoid injury of the subclavian vessels when outside their described safe drilling angle in the medial clavicle [15]. A variety of techniques have been used to determine and describe the anatomy of and around the clavicle. The aim of this study was to further clarify the anatomic relationships of both the subclavian vessels and brachial plexus to the clavicle in fresh frozen cadaveric specimens.
in a serial fashion from the medial to the lateral position using a Nikon D5100 camera based on the 15-mm sections. The clavicle, subclavian vein, subclavian artery, and brachial plexus were identified on photographs. Measurements were made (GIMP software v 2.8.10) and recorded based on these structures. The age and sex of the specimens were recorded. The height and weight data were not available. Microsoft Excel 2013 was used for statistical analysis. Results Five cadaveric specimens were evaluated aged between 64 and 81 (see Table 1). Three of the cadaveric specimens were male and two were female. Student’s t-test was performed between the sexes and no difference in measurements was observed (p = 0.44). The subclavian vein was in the closest proximity to the clavicular cortex of the neurovascular structures identified and measured. The subclavian vein was most closely associated with the clavicle (4.8 mm) medially (Section 1 of 8). In the second section, the vein was still intimately associated with the clavicular cortex at an average of 6.6 mm. The brachial plexus was most closely associated with the clavicle (15.2 mm) at about the middle of the clavicle (Section 4 of 8). The subclavian artery was most closely associated with the clavicle (18.6 mm) near the medial third of the clavicle (Section 3 of 8). In the lateral half of the clavicle (Sections 5–8), none of the structures identified were closer than 2 mm to the clavicular cortex. Moving laterally, the distance of the neurovascular structures from the clavicle increased (see Fig. 1). Discussion
Methods Five fresh frozen cadaveric specimens were sectioned in a sagittal fashion using a band saw (Hobart Corporation). Sections were cut every 15 mm using a ruler on the band saw beginning laterally at the shoulder and extending medially past the sternoclavicular joint. Next, the sections were photographed with a ruler near the centre of the photo to serve as a measurement guide. Section 1 was identified as it contained the sternoclavicular joint. Moving laterally, the final section measured was identified using the acromioclavicular joint. Subsequent photos were taken
Advanced imaging and cadaveric dissection have been used to describe the relationship of the clavicle to the surrounding neurovascular structures. However, there have been no recent cadaveric studies that used sectioning to measure the relationship of the clavicle to the surrounding structures. Our study methods yielded results that are in agreement with previous anatomic and radiographic studies. Most studies suggest that the neurovascular risk is most significant during medial screw placement of the clavicle. The subclavian vein was
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
Clavicular caution: An anatomic study of neurovascular structures Luke Robinson a,*, Federico Persico b, Eric Lorenz c, David Seligson d a
Department of Orthopaedic Surgery, University of Louisville School of Medicine, Louisville, KY, USA Orthopaedic Surgery, Fundacion Valle del Lili, Cali, Colombia c Greifswald University, Greifswald, Germany d Department of Orthopaedic Surgery, University of Louisville, Louisville, KY, USA b
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 11 August 2014
Open reduction and internal fixation of the clavicle is used to treat displaced fractures of the midshaft of the clavicle. Complications of operative intervention include injuries to major neurovascular structures including the subclavian artery and vein. Unlike other surgical approaches, palpation or visualization of the deep neurovascular structures at risk is rarely performed and is not part of the routine approach. This study aims to further elucidate the relationship of major neurovascular structures in the shoulder to the clavicle using sectioned fresh frozen cadaveric specimens. Using five cadaveric specimens, sagittal sections were performed using a band saw. Sections were taken every 15 mm. Using these sections, structures were identified and photos were taken using a standardized approach to allow for precise and accurate measurements. Measurements taken included the distance from the nearest clavicular cortex to the centre of the subclavian artery, vein, and brachial plexus. These measurements were taken from five limbs on five different cadavers. Our results were consistent with previous studies. Medially, the subclavian vein was intimately related medially (4.8 mm) to the clavicle, whereas the artery and brachial plexus were both >2 cm from the clavicle. At about the junction of the middle and second-thirds of the clavicle, all three structures were within 2 cm of the clavicle. Moving laterally, these structures moved further away and at the acromioclavicular (AC) joint were at least 4.5 cm away from the clavicle on average. This study reiterates that the medial third of the clavicle is closely associated with neurovascular structures and that care should be taken here when using drills, depth gauges, and clamps. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Clavicle fracture Clavicle anatomy Clavicle nonunion Clavicle ORIF Complication
Introduction Clavicle fractures comprise around 3% of all fractures in adults and about 80% involve the midshaft [1–3]. While most can be treated nonoperatively with good outcomes [4,5], recent studies have suggested that the surgical treatment of displaced midshaft clavicle fractures may improve functional outcomes and prevent symptomatic nonunion [6,7]. Open reduction and internal fixation (ORIF) of these fractures provides stable anatomic reduction that restores length and prevents symptomatic malunion [8]. However, injuries to the nearby neurovascular structures have been reported as a result of surgical intervention [9–11]. Previous studies have reported on anatomic relationships between the clavicle and the surrounding neurovascular structures.
* Corresponding author. Tel.: +1 859 852 5319; fax: +1 502 852 7227. E-mail addresses: [email protected] (L. Robinson), [email protected] (F. Persico), [email protected] (E. Lorenz). http://dx.doi.org/10.1016/j.injury.2014.08.031 0020–1383/ß 2014 Elsevier Ltd. All rights reserved.
Werner and Reed reported on screw tip contact during simulated ORIF of the middle third clavicle fractures using fresh cadaver specimens based on the plate position both superiorly and anteroinferiorly. They reported no difference in screw tip contact based on the plate position and recommended plating the clavicle with the arm abducted to increase the distance of these structures from the bone [12]. Other studies have taken a more purely anatomic approach. Lo and Eastman reported on the locations of vital structures in fresh cadaveric specimens. Their results suggested that anteroinferior instrumentation on the medial third of the clavicle should be performed with caution due to the proximity of the subclavian artery 15–22 mm from the posterior aspect of the clavicle [13]. Radiological studies have also examined the relationships of neurovascular structures to the clavicle. Using three-dimensional (3D) computed tomographic (CT) arteriograms, one study aimed to describe safe zones for drilling during plating of clavicular fractures. They reported that the subclavian vein is intimately related to the clavicle medially where it was found on average 4.77 mm
L. Robinson et al. / Injury, Int. J. Care Injured 45 (2014) 1867–1869
1868
Table 1 Average measurements of five cadaveric specimens. Measurements taken from photographs. Distances represent the closest distance in millimetres between the clavicle cortex and the vessel or nerve edge. Section number (medial to lateral)
Subclavian artery (mm)
Subclavian vein (mm)
Brachial plexus (mm)
1 2 3 4 5 6 7 8
23.4 3.8 21.5 4.0 18.6 4.8 21.8 9.1 28.5 13.5 35.3 15.2 42.3 16.8 53.1 17.1
4.8 2.6 6.6 4.0 14.1 6.5 20.7 13.1 28.9 18.8 42.8 20.7 52.0 22.3 67.2 20.3
33.4 6.4 25.0 5.2 15.9 4.2 15.2 4.6 21.2 12.3 30.3 13.6 37.8 14.2 48.3 15.3
posteriorly. They also reported that the artery was at a safer 25 mm posterior to the clavicle and that moving laterally the structures were found more posterioinferiorly and were located further from the clavicle [14]. In a separate study using magnetic resonance imaging (MRI), safe drilling angles and depths in the medial half of the clavicle were determined based on parasagittal images. The authors concluded that the drilling depth should be limited to 17 mm to avoid injury of the subclavian vessels when outside their described safe drilling angle in the medial clavicle [15]. A variety of techniques have been used to determine and describe the anatomy of and around the clavicle. The aim of this study was to further clarify the anatomic relationships of both the subclavian vessels and brachial plexus to the clavicle in fresh frozen cadaveric specimens.
in a serial fashion from the medial to the lateral position using a Nikon D5100 camera based on the 15-mm sections. The clavicle, subclavian vein, subclavian artery, and brachial plexus were identified on photographs. Measurements were made (GIMP software v 2.8.10) and recorded based on these structures. The age and sex of the specimens were recorded. The height and weight data were not available. Microsoft Excel 2013 was used for statistical analysis. Results Five cadaveric specimens were evaluated aged between 64 and 81 (see Table 1). Three of the cadaveric specimens were male and two were female. Student’s t-test was performed between the sexes and no difference in measurements was observed (p = 0.44). The subclavian vein was in the closest proximity to the clavicular cortex of the neurovascular structures identified and measured. The subclavian vein was most closely associated with the clavicle (4.8 mm) medially (Section 1 of 8). In the second section, the vein was still intimately associated with the clavicular cortex at an average of 6.6 mm. The brachial plexus was most closely associated with the clavicle (15.2 mm) at about the middle of the clavicle (Section 4 of 8). The subclavian artery was most closely associated with the clavicle (18.6 mm) near the medial third of the clavicle (Section 3 of 8). In the lateral half of the clavicle (Sections 5–8), none of the structures identified were closer than 2 mm to the clavicular cortex. Moving laterally, the distance of the neurovascular structures from the clavicle increased (see Fig. 1). Discussion
Methods Five fresh frozen cadaveric specimens were sectioned in a sagittal fashion using a band saw (Hobart Corporation). Sections were cut every 15 mm using a ruler on the band saw beginning laterally at the shoulder and extending medially past the sternoclavicular joint. Next, the sections were photographed with a ruler near the centre of the photo to serve as a measurement guide. Section 1 was identified as it contained the sternoclavicular joint. Moving laterally, the final section measured was identified using the acromioclavicular joint. Subsequent photos were taken
Advanced imaging and cadaveric dissection have been used to describe the relationship of the clavicle to the surrounding neurovascular structures. However, there have been no recent cadaveric studies that used sectioning to measure the relationship of the clavicle to the surrounding structures. Our study methods yielded results that are in agreement with previous anatomic and radiographic studies. Most studies suggest that the neurovascular risk is most significant during medial screw placement of the clavicle. The subclavian vein was
