Patient Positioning

Patients with rectal cancer are often placed in a modified lithotomy position with their hips and knees slightly flexed and pressure points appropriately protected. The arms are usually bilaterally tucked, although a significantly obese patient may benefit from having one upper extremity placed on an arm-board perpendicular to the operative bed. The most relevant complications associated with lithotomy position are compartment syndrome and peripheral nerve injury, which have been reported after both open and minimally invasive colorectal surgery.[1],[2],[3] The recognized pathogenesis of compartment syndrome is an ischemia-reperfusion injury.[4]

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 lack 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. In this respect, the adoption of minimally invasive surgery has been associated with the prolonged use of steep Trendelenburg position to maximize the favorable effect of gravity in keeping the small bowel away from the operative field (e.g., pelvis or otherwise) and might therefore contribute to 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 regard to peripheral nerve injury, both the upper and the lower extremities are subject to risk. The upper extremity is subject to 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 lesion may present as an atrophic paralysis involving the hand flexors associated with hypoesthesia of the palmar surface. If the cervical sympathetic chain is affected, a Horner’s syndrome with ipsilateral anhydrosis, miosis, and ptosis may be observed. Often times the more distal peripheral nerves are injured rather than the two main trunks originating from the brachial plexus; these injuries are manifested by complex neuropathies as the combination of various simultaneous injuries. 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. Lastly, an ulnar nerve injury can result in numbness of the ulnar side of the hand associated with weakness of the fourth and fifth finger interphalangeal flexion. Brachial plexus injury has been described as compression injury caused by shoulder supports, which should be avoided.[8]

With respect to lower extremity injuries, the sciatic nerve supplies the hamstrings and can be compressed in the gluteal region during prolonged lithotomy position.[9] 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 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).

An obturator nerve injury may result in paresthesia, sensory deficit, or pain in the medial thigh associated with a variable degree of adductor muscle weakness or muscle wasting.

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 burning pain if injured. Similarly, the femoral nerve originates from the lateral psoas muscle, and provides sensation to the anterior thigh and medial aspect of the distal leg. A femoral nerve injury can also affect its related motor component innervating the quadriceps femoris and sartorius muscles, and result in 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 intra-abdominal contents during the course of surgical exposure, particularly in thin patients from the blades inserted into self-retaining retractors.[10]

An alternative positioning system, particularly used in laparoscopic surgery, is the split-leg bed that avoids lower extremity flexion that can cause some of the reported complications associated with modified lithotomy position. No definitive data is available that indicates the split-leg bed is associated with a decreased rate of morbidity associated with patient positioning when compared with the modified lithotomy position, however, many high-volume institutions use this option as a viable positioning alternative to lithotomy in patients at especially high risk of compartment syndrome to avoid complications.

The prone position is also commonly used in treating rectal cancer. Some surgeons advocate the completion of an abdominoperineal resection with the patient in the prone position to facilitate exposure and oncologic excision of the anorectum following initial rectal dissection and colostomy creation in the modified lithotomy position. In addition, a prone position may be preferable when initiating mucosectomy or for inter-sphincteric resection in cases of handsewn coloanal anastomosis before laparotomy or laparoscopy in the lithotomy position. 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 to minimize the risk of brachial plexus neuropathy due to a stretch injury. 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 including the use of the appropriate face cushioning and endotracheal tube protection device when the patient is turned prone to ensure absolute and certain control of the airway.