Shoulder arthroscopy has become a key component in both the diagnosis and treatment of various pathologic conditions of the shoulder. Compared to open procedures, it allows a detailed examination of the glenohumeral joint and subacromial space with minimal morbidity. Basic principles of proper patient positioning are vital to effective arthroscopic surgery. The two positions utilized for shoulder arthroscopy are the lateral decubitus and beach-chair positions, and the method utilized by a given surgeon is dependent on his or her experience and preference. There are specific advantages and disadvantages to each technique, and the arthroscopic surgeon must be aware of the risks and benefits of both positions.
The following five points will summarize these issues.
FIVE POINTS
Point 1: Proper patient positioning requires a systemic approach that is understood by all members of the operative team
Effective patient positioning begins with the appropriate organization of the operating room. The operating table must be arranged so that the surgeon has adequate access to the shoulder. The surgeon must be capable of standing both at the head of the bed and below the level of the arm, and the placement of the anesthesiology team, instrument tables, and arthroscopy tower should facilitate this maneuverability. In particular, the arthroscopy tower containing a video monitor, light source, video control box, and shaver control should be located opposite of the operative shoulder angled so that the surgeon may clearly see the monitor and the control displays of all equipments. These organizational principles apply to both the lateral decubitus and beach-chair positions.
Proper lateral decubitus positioning begins with the patient lying on top of a bean bag covered with a folded sheet. The surgeon stands adjacent to the operative shoulder with one assistant on the other side of the operating table facing the surgeon, and a second assistant at the patient's feet. In a controlled fashion, the surgeon and the first assistant lift the patient using the folded sheet, and turn him or her into the lateral position with the operative shoulder facing up. The second assistant controls the patient's legs while the anesthesiologist controls the patient's head and neck during this maneuver. The patient's axilla is examined to confirm that it is free from any obstruction from the bean bag. The bean bag is then cradled around the patient's hips and torso, and the patient's upper body is tilted 30° posteriorly to align the glenoid parallel to the floor (Fig. 1). Suction is applied to the bean bag to fix its position. The axilla is rechecked to confirm that it is free of any pressure from the bean bag or operating table. A 1-liter bag of saline may be placed under the axilla at this time, if necessary, for padding. The patient's torso and hips are secured to the table with 3-inch cloth tape.
Fig. 1: Illustration of a patient in the lateral decubitus position demonstrating the 30° posterior tilt required to orient the glenoid parallel to the floor. Adequate protection of the opposite arm and brachial plexus is important to avoiding neurologic injury
4The patient's head is elevated with sheets or pads to eliminate deviation towards the nonoperative shoulder, and avoid traction on the brachial plexus. The operating table is rotated 45° away from the anesthesiologist to allow the surgeon adequate access to the shoulder. Examination of the shoulder may now proceed prior to draping with stabilization of the scapula by one hand and manipulation of the arm or humeral head with the other.
Draping is performed to prevent the egress of arthroscopy fluid onto the patient's head and torso while maintaining adequate access to potential portal sites. An adherent u-drape is placed around the axilla with the tails crossing over the neck. Prepping of the arm is performed from the hand to the level of the drape while the traction tower is affixed to the foot of the bed opposite of the operative shoulder. Draping begins with a large sheet that covers the patient's legs and body, and extends to the level of the axilla. A second u-drape is placed around the axilla with tails crossing at the level of the neck. A padded traction sleeve is applied to the arm, and wrapped with a coban wrap. A rope is attached to the end of the sleeve and hung over the traction tower, and 10 lbs of weight are applied to the line (Fig. 2). Two final split drapes are then applied. The first is placed around the axilla with the tails extending towards the head, and second is placed proximal to the shoulder with the tails extending towards the torso. It is imperative that the accessibility to all potential portal sites is achieved.
Fig. 2: Illustration of a patient in the lateral decubitus position following the application of traction. The head and neck are aligned neutral to avoid traction on the brachial plexus. The traction tower provides abduction and forward flexion of the arm to eliminate the need for an arm positioner. The utilization of abduction traction to lateralize the humeral head is a useful adjunct during stabilization procedures
For the beach-chair position, the patient initially lies supine on the operating table. While an operating table with a removable back is optimal for this positioning technique, the patient may be positioned with his or her scapula at the edge of the table to achieve adequate access to the shoulder. Following induction and intubation, the endotracheal tube must be secured to the opposite side of the face to avoid encroachment into the operative field. The head is secured through use of a padded headrest with forehead and chin straps, and a neutral alignment of the neck is confirmed. The head may be rotated slightly away from the operative arm if necessary (Fig. 3). Towels and adhesive tape may be utilized in the absence of a headrest. A pillow is placed under the knees to protect the peroneal nerves. A safety belt is secured across the lap, and the nonoperative arm is secured to the table with either a specialized soft strap or towels and adhesive tape. The head of the bed is elevated until the waist of the patient is flexed to between 45° and 80° to bring the acromion parallel to the floor. While operating tables designed for the beach-chair technique make this positioning easily accomplished through an adjustable back support, any adjustable table can be modified to achieve an adequate position. Many beach-chair tables have a partially removable back support to 5improve access to the posterior shoulder, and this piece is removed at this time.
Fig. 3: Image of a patient in the beach-chair position prior to draping. The head is kept in neutral extension, and may be rotated slightly away from the operative shoulder. Forehead and chin straps secure the head position. The endotracheal tube is secured away from the operative shoulder. The back of the table is elevated so that the patient is flexed at the waist well over 45°. Part of the back support is removed so that the surgeon has adequate access to the posterior shoulder
The table is rotated 45° to give the surgeon adequate access to the entire shoulder. If a mechanical arm positioner is to be utilized, it is attached to the table at this time.
Prior to draping, the operative arm is suspended while the surgical assistant preps the skins from the neck to the hand. A specialized shoulder drape is then applied in a manner which prevents leakage of arthroscopy fluid or contamination of the surgical field. A stockinette is placed over the hand and extended up to the elbow, and secured with coban wrap. If an arm positioner is being utilized, it is now attached to the forearm with the appropriate connection materials. A surgical assistant may also be used to hold the arm during surgery.
Point 2: Advantages of the lateral decubitus position include traction of the operative extremity and a reduced risk of cerebral ischemia
Because the arm is placed in a traction sleeve, there is no need for an assistant or a mechanical positioner to hold the arm. The amount of distraction on the glenohumeral joint may be adjusted by changing the amount of weight on the traction line. The traction tower may also be rotated to bring the shoulder into a more flexed or extended position. Some towers allow the attachment of an additional strap to the upper arm to increase the amount of humeral head lateralization. Because of the traction on the arm and its adjustability, the lateral decubitus position provides excellent visualization for the glenohumeral joint during stabilization procedures or repairs within the joint. This visualization is further improved when lateral traction can be applied to the humeral head. Another advantage of the lateral decubitus position is the reduced risk of cerebral ischemia during intraoperative hypotension. Because the brain lies in a dependent location, the anesthesiologist may make a reasonable assessment of cerebral perfusion based on the cardiovascular recordings. Hypoperfusion injuries of the brain are rarely encountered with this surgical position.
Point 3: Disadvantages of the lateral decubitus position include the risk of malpositioning, limited accessibility to the anterior shoulder, and the risk of peripheral neural injury
Because there are many steps to placing the patient in the lateral decubitus position, there are multiple opportunities for the patient to be positioned suboptimally. Lifting and turning the patient requires four people to correctly perform this maneuver. If the patient is not sufficiently tilted posteriorly, visualization will be compromised. If the bean bag is not hardened sufficiently or loses suction during the procedure, the patient will not be adequately stabilized. There is also a tendency of the traction tower to internally rotate the shoulder, which may compromise external rotation following capsulorrhaphy if this rotation is not recognized intraoperatively. Various types of neurologic injuries have been described for the lateral decubitus position. Neuropraxias of the brachial plexus have been observed and are usually the result of excess traction on the arm or malpositioning of the neck. For these reasons, traction in excess of 15 lbs is avoided, and the neck must be positioned so that it is not deviated towards the floor. Injury to the brachial plexus may also occur from prolonged axillary pressure during surgery. The axilla should be checked during positioning to confirm that it is not obstructed and an axillary roll should be placed if necessary to avoid excess pressure. Peroneal nerve palsies have also been reported and are typically due to inadequate padding of the legs. Prior to prepping and draping, each leg must be checked to confirm that it is well-padded to avoid pressure from the table, bean bag, or the opposite leg.
Point 4: Advantages of the beach-chair position include its Arthroscopic orientation, Availability to both arthroscopic and open procedures, accessibility to the entire shoulder, and decreased risk of peripheral nerve injury
Because the patient is in a semi-seated position with the head towards the ceiling and the arm at the side, the beach-chair position replicates the orientation of the shoulder during physical examination or radiographic assessment. For this reason, the surgeon is less likely to become disoriented during arthroscopic visualization. This position may also decrease the learning curve for surgeon just learning shoulder arthroscopy. Because the surgeon has good accessibility to the anterior, lateral, and posterior sides of the shoulder, this position does not hinder the conversion from an arthroscopic to an open procedure, and there is no need to reposition the patient. The absence of continuous traction on the arm decreases the risk of neurologic injury; particularly, in the bracial plexus. Patients also may tolerate the beach-chair position better than lateral decubitus, so less sedating anesthesia may be required as long as a peripheral nerve block is utilized.
Point 5: Disadvantages of the beach-chair position include the need of a surgical Assistant or Arm positioner, limited visualization during stabilization procedures, and an increased risk of cerebral hypoperfusion
Because the arm is left free from a traction device in this position, either a surgical assistant or a mechanical arm positioner is important for holding the arm. Arm mobility and manipulation are important for adequate visualization using this positioning technique, and the surgeon is unable to both hold the arm and operate simultaneously. The lack of traction on the arm compromises visualization of and access to the axillary recess and the posterior glenohumeral joint. For this reason, stabilization procedures such as capsulorrhaphy or labral repair are more difficult than in the lateral decubitus position. Cerebral hypoperfusion with ischemic injury is a serious complication that has been reported for the beach-chair position. This may occur due to the theoretical fight of blood flow against gravity to reach the brain. Ischemic injury may occur because the head is situated above the level of cardiovascular monitoring equipment, and the brain may be hypoperfused even though cardiac monitors suggest adequate peripheral perfusion. Several steps should be undertaken to avoid this sometimes devastating complication. While relative hypotension improves surgical efficiency by decreasing bleeding, significant hypotension must be avoided, and cardiovascular recordings must be closely controlled by the anesthesiologist. Likewise, the anesthesiologist must check the alignment of the head and neck throughout the procedure. External cerebral perfusion monitors are very helpful towards a close regulation of perfusion pressures and avoidance of ischemia.
In conclusion, there are both advantages and disadvantages to the lateral decubitus and beach-chair positions. Selection of position should be based on surgeon preference and experience, and the pathology being addressed. A systemic approach by the entire surgical team facilitates efficiency of the arthroscopic procedure, and helps to avoid potential complications.
ADDITIONAL READING
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- Papadonikolakis A, Wiesler ER, Olympio MA, et al. Avoiding catastrophic complications of stroke and death related to shoulder surgery in the sitting position. Arthroscopy. 2008; 24 (4): 481-2.
- Peruto CM, Ciccotti MG, Cohen SB. Shoulder arthroscopy positioning: lateral decubitus versus beach chair. Arthroscopy. 2009; 25 (8): 891-6.
- Pohl A, Cullen DJ. Cerebral ischemia during shoulder surgery in the upright position: a case series. J Clin Anesth. 2005; 17 (6): 463-9.
- Rains DD, Rooke GA, Wahl CJ. Pathomechanisms and complications related to patient positioning and anesthesia during shoulder arthroscopy. Arthroscopy. 2011; 27 (4): 532-41.
- Skyhar MJ, Altchek DW, Warren RF, et al. Shoulder arthroscopy with the patient in the beach-chair position. Arthroscopy. 1988; 4 (4): 256-9.