Clavicular osteotomy to assess subclavian vein injury during internal fixation of midshaft clavicle fractures

Abstract

Midshaft clavicle fractures are commonly fixed with locking plates. The subclavian vein risks injury during this procedure and the consequences can be fatal. The purpose of this present study is to describe a clavicular osteotomy technique in order to equip orthopaedic surgeons with a means of rapidly accessing a subclavian vein injury. The osteotomy should only be performed following an urgent intraoperative vascular surgery assessment. There must be shared consensus from both orthopaedic and vascular surgery that direct repair of the subclavian vein is necessary, and further exposure is required. The results of the technique performed on thirteen embalmed cadaveric specimens are also included. The osteotomy was able to expose 3.16 cm (SD = 0.60) of the subclavian vein and both the fracture and osteotomy site of all clavicles (100%) were able to be reduced and fixed using a single pre-contoured fifteen-hole lateral plate intended for use on the contralateral shoulder. This surgical technique study confirms that in the rare circumstance that the osteotomy is utilized, adequate exposure of the subclavian vein is achieved.

Introduction

The clavicle is a commonly fractured bone in an active population. ¹ It accounts for approximately 2.5−5% of all fractures. ² Approximately two thirds of these fractures occur at the mid-shaft.^2,3 Indications for fixation of mid-shaft clavicular fractures include open fractures, skin tenting, a floating shoulder, pleural injury, neurovascular compromise and shortening of greater than two centimetres.^4–7 Internal fixation leads to improved functional outcomes, union rates and cosmesis.^3,8,9

Surgical fixation of midshaft clavicle fractures is commonly performed by the use of superior pre-contoured plates. ⁹ Although rare, this does carry a risk of iatrogenic neurovascular injury. This includes injury to the subclavian vein which is documented to be within 5mm posterior to the medial clavicle.^10–13 This is a potentially disastrous complication of a fracture that generally is not considered life or limb threatening. ¹¹

When subclavian vein bleeding is suspected, there are no established algorithms as to how best manage this life-threatening injury. This surgical technique study describes the use of a clavicular osteotomy two centimetres lateral to the sternoclavicular joint in the setting of suspected subclavian vein injury during midshaft clavicle fixation. The aim is to equip the orthopaedic surgeon with a method of rapidly assessing suspected iatrogenic subclavian vein injury and subsequent management.

Indications

The indications for this technique are very limited. This technique should only be used in suspected iatrogenic life-threatening subclavian vein injury during midshaft clavicle fixation, where the clavicle is already exposed, and vascular surgery deem direct repair to be the most appropriate management following an urgent intraoperative assessment. It should only be performed by experienced orthopaedic surgeons capable of using an oscillating saw in proximity to major neurovascular structures. It should only be used when other less invasive means of exposing the suspected injured section of the subclavian vein, such as mobilization of the medial fragment is not possible

Contraindications

This technique should not be performed when the patient is in beach chair position. The head must be tilted down to prevent air embolus. ¹⁴

Surgical technique

Set up

Once injury to the subclavian vein is suspected the operative site must be filled with wet packs and held with steady manual pressure. The patient must then be placed supine with head down tilt to prevent air embolus. ¹⁴ It is important to communicate promptly with anaesthetic and theatre staff to adjust the bed position and initiate blood and crystalloid resuscitation. The possibility of this rare but catastrophic event occurring should be raised with theatre staff during the preoperative surgical time out, with wet packs being readily available from the beginning of surgery. Vascular surgery should be consulted immediately to prevent delay in the definitive management. Following an intraoperative assessment by vascular surgery, if there is shared consensus from both vascular and orthopaedic surgery that it is the subclavian vein that may be injured, rather than a smaller branch vessel or tributary, and that direct repair is warranted, the orthopaedic surgeon should then attempt to mobilize the fracture to gain access to the subclavian vein, and if this is inadequate, proceed to performing the clavicular osteotomy Figure 1.

Figure 1.

This flowchart depicts an algorithm for orthopaedic surgeons to follow when faced with the possibility of subclavian vein injury during midshaft clavicle fixation.

Technique

The site of osteotomy is dependent on the region where the subclavian vein is thought to be injured. It should allow enough exposure to visualize the vessel and allow end to end control. This investigation studied the utility of a clavicular osteotomy 2cm lateral to the sternoclavicular joint, as this would be comfortably medial to the most medial drilling trajectory in midshaft clavicle fixation and allow enough bone for fixation following the osteotomy. More medial osteotomy positions may put the subclavian vein further at risk, as it has been documented to be closest to the clavicle one-centimetre lateral to the sternoclavicular joint, and possibly tethered to the periosteum at this point.^11–13 The skin incision may need to be extended medially to facilitate the osteotomy Figure 2.

Figure 2.

This is an illustration of the clavicular osteotomy in a right sided mid shaft clavicle fracture. A simple oblique midshaft clavicle fracture is depicted and the osteotomy is displayed two centimetres lateral to the sternoclavicular joint. The reference point where measurements were made from the subclavian joint is also depicted. The subclavian vein can be seen exposed following removal of the medial clavicular fragment. The relationship of the subclavian artery to the vein is also highlighted. The artery was not visible in the dissections performed.

The osteotomy is performed using an oscillating saw. In order to prevent further damage to the subclavian vein, two blunt levering retractors are placed on the superior and inferior aspect of the medial clavicle, protecting the structures behind the clavicle. Subperiosteal dissection of the medial fragment is then performed, and a bone lever can be placed carefully underneath the clavicle to avoid plunging with the saw. Retractors and bone levers must not be inserted blindly as this may further damage the subclavian vein. Muscle and periosteal attachments were removed from the fragment lateral to the osteotomy allowing for its temporary removal. The subclavian vein should then be identified and carefully assessed for perforation with the assistance of vascular surgery Figure 3.

Figure 3.

This image is of a right cadaveric shoulder. There is a simulated fracture of the midshaft of clavicle and osteotomy two centimetres lateral to the sternoclavicular joint, the resulting medial clavicular fragment is removed. The subclavian vein and its tributaries are painted in blue. The exposure of the subclavian vein achieved by the osteotomy and the position of the vein directly posterior to the medial clavicle can be appreciated.

Structures at risk

Other than the subclavian vein, the subclavian artery should not be visible and at a safe distance away from the operating area. It is protected by scalenus anterior which separates the vein from the artery and is approximately 26mm posterior to the posterior cortex at the medial third of the clavicle.^11,12 The artery loses protection from scalenus anterior at the midshaft of clavicle where it is most at risk and is located posteroinferior to the clavicle. The brachial plexus is also protected by scalenus anterior medially and is most at-risk posteroinferior to the clavicle near and lateral to the midshaft.^11,12,15

Reduction and fixation

Following repair of the subclavian vein, or exclusion of subclavian vein injury. Both the fracture and osteotomy site are fixed using a single pre-contoured fifteen-hole lateral clavicle plate intended for use on the contralateral shoulder, with the acromial end used on the sternal end of the affected clavicle.

Rehabilitation

The patient is placed in a sling post operatively and made non weight bearing for at least six weeks. The wound is reviewed at 2 weeks post-operative. They may require antiplatelet or anticoagulant therapy depending on the vascular surgeon involved. A radiographic and clinical review is performed at six weeks post operatively with view to allow weight bearing at this stage.

Cadaveric dissections

Methods

This technique was performed on thirteen shoulders from eight embalmed whole-body cadaveric specimens. Some shoulders of certain cadaveric specimens were not used due to resource allocation by the laboratory. None of the shoulders had any previous injury or surgery to the shoulder girdle. The surgical exposures were performed by a post graduate year two level surgical resident, and an orthopaedic trauma fellow; after hands-on instruction and demonstration by a fellowship trained orthopaedic shoulder surgeon.

The dissections were performed in the Department of Anatomy and Neuroscience at the University of Melbourne, Australia, between January and May 2019. Ethics approval was obtained via the Anatomy and Neuroscience Humans Ethics Advisory Group at the University of Melbourne.

The clavicle was exposed in the routine manner, as would be performed in superior plating of a midshaft fracture. A midshaft clavicle fracture was then recreated using a saw, osteotome and mallet at the midpoint of the clavicle and then the described osteotomy and fixation technique used.

The reference point of the sternoclavicular joint for measurement was at the most medial end of the clavicle, at the halfway point between the superior and inferior margin.

Descriptive statistics were used for the reporting of data. The following sets of data were obtained.

• Gender and side of the cadaver

• Length of clavicle

• Length of subclavian vein exposed by osteotomy

• The pre-contoured clavicular plate used for internal fixation

Results

Thirteen shoulders of eight cadavers were dissected. Six of the cadavers were male and two were female. The average length of clavicle was 16.25 cm + /−0.73 (n = 13, SD = 1.12). The average length for males was 16.49 + /−0.76 (n = 11, SD = 1.29). The average length for females was 14.9 + /−1.18 (n = 2, SD = 0.85).

The osteotomy was able to expose the subclavian vein in all specimens. The vein was not damaged in any of the specimens. The average length exposed was 3.16 + /−0.33 cm (n = 13, SD = 0.61). The average length exposed on the right side was 3.01 + /−0.47 cm (n = 7, SD = 0.64) and 3.33 + /−0.47 cm (n = 6, SD = 0.58) on the left. The average length exposed in males was 3.22 + /−0.38 cm (n = 11, SD = 0.65). The average length exposed in females was 2.85 + /−0.29 cm (n = 2, SD = 0.21).

Both the fracture and osteotomy site of all clavicles (100%) were able to be reduced and surgically fixated using a single pre-contoured fifteen-hole lateral plate intended for use on the contralateral shoulder (See Figure 4). At least three screws were able to be implanted lateral to the midshaft fracture, three within the removed fragment, and three medial to the clavicular osteotomy.

Figure 4.

This illustration reveals how both the osteotomy and the fracture site can be reduced and fixated using a single plate from a standard clavicular fixation system. A fifteen-hole lateral clavicle plate intended for use on the contralateral shoulder is depicted, with the end intended for use on the contralateral acromion being used for fixation of the sternal end of the injured clavicle.

Discussion

This surgical technique study reveals a last resort method of reliably exposing a portion of the subclavian vein suspected to have been injured during midshaft clavicle fracture fixation. Using embalmed cadaveric specimens, we found that by osteotomising the clavicle two centimetres lateral to the sternoclavicular joint, in an already fractured midshaft of clavicle, approximately 3.16 + /−0.30 (SD = 0.60) of subclavian vein can be exposed. The segment of subclavian vein exposed is posterior to the osteotomy site extending inferiorly and laterally towards the axilla before it is lost to vision beneath the chest musculature. Both the fracture and osteotomy site of all clavicles were able to be internally fixed using a contralateral contoured fifteen-hole lateral clavicle plate. The ability to reliably expose approximately 3 cm of the subclavian vein using the assessed osteotomy technique may assist surgeons in their assessment and the direct repair of an iatrogenic injury to the subclavian vein.

Iatrogenic injuries of the subclavian vein are a known but rare and seldom documented injury. It is mainly at risk during excessive plunging when drilling. This is when the drill bit obtrudes further from the distal cortex than the surgeon intended. It may also occur with use of the depth gauge, incorrect screw length or when mobilizing the fracture.^14,16,17 There are only two reported cases of screw contact with the subclavian vein. These presented post operatively as deep vein thrombosis and as dynamic subclavian vein compression during arm elevation.^18,19 Three further life-threatening cases were identified intraoperatively. These include one case of vein laceration occurring due to mobilization of bone fragments, unfortunately little is documented about this event but the patient's outcome is reported to be good. ²⁰ One case where the subclavian vein was directly penetrated by a drill at the midshaft of clavicle during superior plating, where vascular surgery consult and repair was required. ²¹ And most notably, one case where the injury was fatal. The cause of death was found to be air embolism and excessive haemorrhage due to right subclavian vein perforation from plunging. ¹⁴

Despite the lack of reported cases, there is concern for subclavian vein injury due to the documented proximity of the structure to the overlying clavicle. Robinson and Sinha’s anatomical studies identified the subclavian vein to be the closest neurovascular structure to the clavicle, approximately 5mm from the medial end.^12,13 The risk of injury is further characterized by Stilwell's study of the plunging depth of orthopaedic surgeons, where nine participants at trainee level or above plunged to a distance greater than 5 mm. ²²

Anteroinferior plating is an alternative option, which has the benefit of less hardware prominence and reduced rates of implant removal. ²¹ This method of fracture fixation has been shown to have similar rates of union and side effects to superior plating. ²¹ In terms of risk to neurovascular structures, anteroinferior plating is thought to mitigate some of the risk due to the trajectory of the screws aiming cephalad, thereby avoiding the neurovascular structures posterior or inferior to the midshaft of clavicle. ¹² However, its most medial screw holes, where the screws aim anterior to posterior, carry a greater risk than superior plating as the vein can be directly behind the clavicle at this point, and sometimes can even be tethered to the posterior cortex.^12,23 Other surgical techniques such as intramedullary nails can also mitigate the risk of neurovascular injury. However, this method of fixation is biomechanically inferior to plating, ²⁴ has a higher rate of fixation failure and may not be applicable to highly comminuted or segmental fracture patterns.^25,26 For these reasons, plating of midshaft clavicle fractures remains a required surgical option and surgeons would therefore greatly benefit from a means of rapidly assessing iatrogenic subclavian vein injury.

There are a few weaknesses to this technique that warrant discussion. Firstly, the osteotomy is not without risks. Only surgeons comfortable with using an oscillating saw in close proximity to the underlying subclavian vein may utilize this technique. Nonetheless, the purpose of this procedure is to serve as a time critical surgical option in a potentially catastrophic situation. In addition, the portion of subclavian vein is exposed is from directly behind the osteotomy site and approximately 3.16 + /−0.30 (SD = 0.60) centimetres lateral before it is no longer visible as it extends towards the axilla inferiorly and laterally. If injury is suspected to have occurred outside of this window the osteotomy technique is not a viable option. Finally, the exposure and results of this study does not reliably assess a situation where the clavicular fixation was for non-union, malunion or a delayed fracture. In these scenarios, due to altered anatomy there may be an increased risk of subclavian vein injury, and the suggestion of a fifteen-hole plate to fix both the osteotomy and fracture site may not be applicable.

To further the findings of this investigation, and the utility of this osteotomy technique, if the osteotomy is utilized, case reports should be done to establish whether the technique is a viable option. Follow up studies could then assess how and if the fracture went on to union and the long-term consequences of the osteotomy.

Conclusion

To the investigator’s knowledge, this is the first study that has evaluated a means of rapidly assessing subclavian vein injury in the setting of midshaft clavicle fracture fixation. The reported literature suggests that air embolism, rather than haemorrhage may be the cause of death in the setting of acute iatrogenic subclavian vein injury following clavicle fixation. The optimal course of management therefore may be to pack the wound with wet packs, apply steady manual pressure, fluid resuscitate the patient and contact vascular surgery. If the vascular surgeon deems it prudent to directly explore and repair the subclavian vein laceration, this technique provides an effective visualization of the presumably damaged segment in this setting. Further clinical experience with this technique will determine if it may be recommended in this situation.