Patient Positioning

Patients with rectal cancer are often placed in modified lithotomy positioning with their hips and knees slightly flexed and pressure points appropriately protected. The upper extremities are often bilaterally tucked, although a patient with significant obesity may benefit from having one upper extremity placed on an arm-board perpendicular to the operative bed. The most relevant complications associated with lithotomy positioning are compartment syndrome through an ischemia-reperfusion injury, and peripheral nerve injuries, which have been reported after both open and minimally invasive colorectal surgery.[1][2][3]

Ischemia of the lower extremity can be caused by a variety of factors and is mainly related to Trendelenburg positioning rather than the lithotomy position. A number of additional factors can adversely affect lower extremity perfusion, particularly the lack of or improper functioning of compression stockings, compression directly applied by members of the operative team, a lithotomy position maintained for longer than 4 hours, and the degree of leg elevation and abduction.[4] In this respect, the adoption of minimally invasive surgery has been associated with the prolonged use of steep Trendelenburg positioning to maximize the effect of gravity in keeping the small bowel away from the operative field (e.g., pelvis) and might therefore contribute to an increased risk of compartment syndrome. A number of patient-related factors have also been identified, including male sex, older age, obesity (particularly when the body mass index exceeds 35 kg/m²), diabetes mellitus, peripheral vascular disease, smoking, and any other underlying conditions causing neuropathy.[5][6][7] In addition, a difficult operation can result in increased operative time or intraoperative bleeding, leading to hypotension and/or hypothermia that can further add to the risk of compartment syndrome.

In a peripheral nerve injury, both the upper and lower extremities are at risk. The upper extremity is at risk for brachial plexus neuropathy, a term that includes several possible peripheral nerve injury manifestations. Specifically, an upper brachial plexus problem can present with adduction and internal rotation of the arm as well as wrist flexion associated with a sensory deficit over the lateral aspect of the upper extremity. The lower brachial plexus injury may present as an atrophic paralysis involving the hand flexors associated with hypoesthesia of the palmar surface. When the cervical sympathetic chain is affected, Horner syndrome (also known as oculosympathetic paresis) with ipsilateral anhidrosis, miosis, and ptosis may be observed. Often, the more distal peripheral nerves are injured; these injuries are manifested by complex neuropathies. For example, a lesion of the musculocutaneous nerve can result in weakened elbow flexion and paresthesia on the radial aspect of the arm. Axillary nerve lesions can affect the deltoid muscle, including variable degrees of atrophic weakness and numbness. Isolated median nerve injury can result in paresthesia and paralysis of the thenar muscles, specifically affecting thumb abduction and opposition. Last, an ulnar nerve injury can result in numbness of the ulnar aspect of the hand associated with weakness of the fourth and fifth digit interphalangeal flexion.[8][9] Brachial plexus injury has been described as a compression injury caused by shoulder supports, which should be avoided.[10][11]

Regarding lower extremity injuries, the sciatic nerve supplies the hamstrings and can be compressed in the gluteal region during prolonged lithotomy position.[8] This injury can produce weakness or paralysis of the hamstring muscles and the muscles distal to the knee associated with sensory deficits over the lateral aspect of the leg. One branch of the sciatic nerve is the common peroneal nerve, which can be compressed during positioning in stirrups and result in sensory deficits of the dorsal foot and the lateral aspect of the distal lower extremity associated with a deficit of dorsiflexion and eversion of the ankle (foot drop) with associated gait disturbances (e.g., steppage gait).[12]

An obturator nerve injury may result in paresthesias, sensory deficits, or pain in the medial thigh associated with a variable degree of adductor muscle weakness or muscle wasting. Overall, obturator nerve injury is rare in a standard total mesorectal excision. However, it is an injury that can occur with a lateral pelvic lymph node dissection that is performed with a dissection of extramesorectal lymph nodes.[13]

The lateral cutaneous nerve of the thigh courses along the psoas muscle and provides sensation to the lateral aspect of the thigh, which can result in numbness or a burning pain when injured. Similarly, the femoral nerve originates from the lateral psoas muscle and provides sensation to the anterior thigh and to the medial aspect of the distal leg. A femoral nerve injury also can affect its related motor function innervating the quadriceps femoris and sartorius muscles, which can cause lower extremity weakness, particularly when initiating ambulation. Both the femoral nerve and the lateral cutaneous nerve of the thigh are at risk of compression injury due to prolonged retraction of the viscera during the course of surgical exposure; this risk is greater in thin patients given how the blades of self-retaining retractors are positioned.[14]

An alternative positioning system, often used in laparoscopic surgery, is the split-leg bed that avoids lower extremity flexion and avoids some of the reported complications associated with modified lithotomy positioning. No definitive data are available indicating that the split-leg bed is associated with a decreased rate of morbidity associated with patient positioning compared with the modified lithotomy position; however, many high-volume institutions use this option as a viable positioning alternative to lithotomy. This option is particularly useful in patients at high risk of compartment syndrome which include male sex, age < 60 years, diabetes mellitus, hypothyroidism, bleeding diatheses, preexisting vascular disease, intra-pelvic pathology, increased muscle mass, deformity of the lower extremity, and a BMI >25.[3] Other known techniques to minimize compartment syndrome are minimizing the time in lithotomy, minimizing the time the legs are higher than the right atrium, and avoiding hypotension. Returning the table to the horizontal position form Trendelenburg has been a suggested preventative measure.[15][16]

The prone position is also commonly used in treating patients with rectal cancer. Some surgeons advocate the completion of the perineal portion of an abdominoperineal resection with the patient in the prone position to facilitate exposure and the quality of excision of the anorectum following an initial rectal dissection and colostomy creation in the modified lithotomy position. In addition, a prone position may be preferable when initiating a mucosectomy or for intersphincteric resection in cases of a handsewn coloanal anastomosis. When using the prone position, surgeons should ensure that the position of the joints of the upper extremity are not flexed at an obtuse angle, which increases the risk of brachial plexus neuropathy due to stretch. In addition, a separate bed should be prepared and pre-arranged prior to completing the initial portion of the case in the lithotomy position. Furthermore, coordination with anesthesiology colleagues is key as is the use of the appropriate face cushioning and endotracheal tube protection device when the patient is turned prone to prevent tissue injury or loss of control of the airway.[17][18]