25: Flexor Pronator Slide

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Procedure 25 Flexor Pronator Slide

Harry A. Hoyen, Patrick J. Messerschmitt

Indications

image A sustained functional impairment of the spastic upper extremity with a fixed forearm pronation, wrist flexion, and finger flexion deformity.

image Some retained voluntary motor control of forearm supination, wrist extension, and finger extension must be present.

image This is more commonly recommended in an established Volkmann forearm contracture.

Examination/Imaging

Clinical Examination

image Preoperative examination of the upper limb reveals a fixed contracture of the forearm in pronation with contracture of the wrist and fingers. Grasp and release motions of the hand are impaired owing to the fixed wrist position.

image In a forearm Volkmann contracture, there is volar deep soft-tissue adhesions and fibrosis. There is often some retained finger and thumb flexion.

Surgical Anatomy

image Pertinent surgical structures include the volar forearm musculature, ulnar nerve, median nerve, brachial artery, and neurovascular structures adjacent to the interosseous membrane.

image Unlike other contracture release procedures, the proximal anatomy is more relevant in this surgical procedure. The location of the median and ulnar nerves in the proximal forearm is vitally important.

Positioning

image The patient is positioned supine with the arm extended onto a surgical arm board.

image A nonsterile tourniquet is placed high on the arm before surgical preparation to allow better visualization during the procedure. Dissection in the proximal forearm and elbow may be necessary.

Exposures

image An anteromedial, longitudinal incision at the elbow situated over the medial epicondyle (Fig. 25-1) is made.

image Superficial dissection includes identification and protection of the medial antebrachial cutaneous nerve. Wide subcutaneous flaps are necessary from the cubital tunnel region to the anterior forearm.

image

FIGURE 25-1

Pearls

It may be difficult to establish a plane between the flexor-pronator fascia and the subcutaneous tissue. There are multiple perforating vessels to the dermal layer that will require coagulation.

The dissection needs to extend to the median nerve as it enters between the deep and superficial heads of the pronator teres. This is similar to the exposure for a submuscular ulnar nerve transposition.

Procedure

Step 1

image The ulnar nerve is identified proximal to the medial epicondyle, and a decompression is performed through to the deep flexor carpi ulnaris muscle fibers.

image The anterior dissection involves a similar decompression of the median nerve as it enters the flexor musculature. The nerve needs to be completely free of adhesions to the flexor-pronator muscles such that the entire muscle group can slide distally after it is released.

image A plane should be established between the posterior and anterior exposures. This plane is just anterior to the elbow capsule and the anterior band of the medial collateral ligament.

image The entire flexor-pronator mass is then dissected from the medial epicondyle origin. It is elevated from the anterior elbow capsule and proximal portion of the intraosseous membrane (Fig. 25-2).

image The lateral border of the flexor digitorum superficialis, palmaris longus, and flexor carpi radialis is elevated from the intraosseous membrane. The median nerve has terminal motor branches in this region and requires careful dissection. The deep portion of the entire muscle group is then elevated.

image Dissection extends to the deep portion of the muscle origin.

image

FIGURE 25-2

Step 1 Pearls

Identify the ulnar nerve proximally and release the cubital tunnel in a distal direction.

The deep dissection will permit identification of the medial collateral ligament. In cases of an elbow contracture, it may be difficult to separate the structure.

The flexor-pronator muscle group needs to be sufficiently mobilized from the elbow capsule and ligament such that the ulnar nerve can be transposed.

Step 1 Pitfalls

The median nerve motor branches are directly within the deep exposure of the pronator. The distal motor branches are at risk during the more anterior exposure.

Step 2

image At the conclusion of the release, the entire flexor-pronator muscle origin will migrate distally (Fig. 25-3A and B).

image This slide effectively translates the muscle origin distally to lengthen the muscles and allow greater supination, wrist extension, and finger extension (Fig. 25-4).

image A submuscular transposition of the ulnar nerve is usually necessary. The ulnar nerve is placed adjacent to the median nerve in the anterior forearm.

image image

FIGURE 25-3

image

FIGURE 25-4

Step 2 Pearls

The tourniquet should be deflated and meticulous hemostasis obtained before wound closure.

Postoperative Care and Expected Outcomes

image The forearm and hand are immobilized with long-arm dorsal and volar splints that hold the fingers and wrist in near full extension, with concomitant elbow extension and forearm supination.

image After the swelling subsides, the splint can be changed into a cast.

image The immobilization is continued for 1 month and then advanced to a full-time splint that is forearm based to keep the wrist and fingers in extension. The splint is removed for hygiene purposes and for daily exercises.

image There is gradual transition of the splint to a night-time splint over the next several months.

image Unrestricted activities usually resume 3 to 4 months postoperatively, although in more chronic cases, a splint is worn during rest periods for several additional months.

Acknowledgment

We would like to give special thanks to the author of this chapter in the previous edition, Ann E. Van Heest, whose work served as an excellent foundation for and contribution to this chapter.

Evidence

Inglis AE, Cooper W. Release of the flexor-pronator origin for flexion deformities of the hand and wrist in spastic paralysis. J Bone Joint Surg [Am]. 1966;48:847-857.

White WF. Flexor muscle slide in the spastic hand: the Max Page operation. J Bone Joint Surg [Am]. 1972;54:453-459.

These classic articles describe the release of the flexor-pronator origin to effectively lengthen the muscles that originate from the medial epicondyle. Treatment options and outcomes are outlined. (Level IV evidence)

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