Management of Complications in Common Hand and Wrist Procedures (eBook)

1 Management of Complications of Flexor Tendon Surgery

Peter C. Amadio and Duncan Angus McGrouther

Abstract

Adhesions are the most common and troubling complication after flexor tendon repair in the hand. Aside from small children, essentially every tendon repair is complicated by adhesions that limit motion; the only real question is whether these will be severe enough to require surgical intervention in an attempt to improve function. Pulley loss can be the result either of direct injury or a decision by the surgeon to trim pulleys to improve motion. Usually, if the contiguous loss is less than 2 cm, reconstruction is not needed. Management of flexor tendon repair rupture will be focused by the history, exploration, and forensic examination of the wound to establish causation and identification of preventable factors. Key technique changes for primary or re-repair have been the move toward stronger repairs by multistranded core suture configurations, better anchorage points, and pulley release. Most therapy regimes aim at active mobilization and this is also indicated for a re-repair as the stuck tendon is vulnerable to rupture from later mobilization. The key to managing infection lies in understanding how the time-honored surgical principles of drainage, decompression, and dilution fit into modern understanding of inflammation and bacterial virulence factors. Infection in a tendon repair is uncommon and usually due to inadequate debridement or comorbidities. It is best managed by antibiotics, drainage, and catheter irrigation. If the tendon is necrotic, it should be excised and reconstruction considered.

Keywords: Keywords: tendon, adhesion, bowstringing, pulley, rupture, infection

1.1 Management of Flexor Tendon Adhesions

1.1.1 Definition/Problem: Current Understanding of the Biology of Adhesion Formation

The observation “one wound, one scar” as it pertains to tendon repair is nearly as old as the specialty of hand surgery itself, and of course is a truism that reflects wound healing biology for nearly all tissues in nearly all mammalian species beyond the fetal stage. The functional implications and severity will vary depending on location, mechanism of injury, and the specific tissues that are injured. The flexor tendons in the hand are especially at risk for the negative consequences of this dictum—the gliding tendon fixed in place by scar to adjacent pulley and bone, limiting tendon excursion and impairing function.

The unique anatomy and nutritional arrangement of the flexor tendons in the hand particularly predispose them to adhesion formation because, even normally, the nutritional supply is precarious. The flexor profundus excursion is around 2.5 cm in the adult finger. This long excursion is made possible by a special nutritional arrangement. Instead of a circumferential paratenon to supply nutrients to the tendon, the blood supply of the finger flexors in the fingers is segmental, through the vincula, which arise from the digital arteries at the joint level, and enter the tendons through their dorsal surfaces (Fig. 1‑1). The feeding vessels enter just lateral and anterior to the bone, just proximal and distal to each joint. These feeding vessels must be carefully protected during dissection at the time of repair or tenolysis. If they are cut, even with a physically intact vinculum, the tendon will be effectively devascularized. To supplement this nutritional source, the tendons are surrounded by a synovial sheath also, so that synovial diffusion can provide nutrition as well. Both systems are commonly injured when the flexor tendon is lacerated, the synovial sheath by the same injury that injured the tendon, and the vincula either by that mechanism or by rupture with muscular contraction, pulling the proximal tendon stump out of the finger.

Unsurprisingly, this loss of nutrition has consequences, and one of the major drivers of adhesion severity is vascularity. Well-vascularized tendons have better motion than poorly vascularized ones, strongly suggesting that a good tendon blood supply is an important factor in reducing adhesion severity.1 This is not only true for severely devascularized tendons, as occurs with amputation/replantation, but also with damage to the vincular system in an otherwise well-perfused finger. Avascular or hypovascular tendons, like any other vascularly impaired tissue, will release cytokines such as vascular endothelial growth factor (VEGF) that will stimulate neovascularization and new vascular ingrowth into the tendon. These new vascular connections, occurring in parts of the tendon normally nourished either by synovial fluid or the vincular system, do good in restoring nutrition to the tendons and aiding tendon healing, but at the same time do harm by binding the tendon to the surrounding tissues and limiting tendon motion. Usually, unfortunately, there is little that can be done to reverse this aspect of the initial injury—though as noted in the next section, there are some things that can be done to try to minimize the impact of tendon hypovascularity on tendon motion.

A second anatomical feature predisposing finger tendons to adhesions is the fibro-osseous sheath, which holds the tendons close to bone and allows the tendon excursion to drive a remarkable 270 degrees of combined active motion of the finger joints. These narrow confines can easily limit gliding of even the smoothest tendon repair, and provide an extremely short leash for any adhesions that do form. However, unlike vascularity, whose loss is currently irretrievable, there are some things that the surgeon can do to mitigate the impact of the sheath on adhesion formation, as discussed below.

Other anatomic factors predisposing to adhesions relate to associated injuries, which may affect tendon vascularity at a distance, require immobilization or otherwise compromise the physical aspects of tendon rehabilitation (fracture, nerve repair, proximal limb injury), or otherwise limit patient ability to participate in rehabilitation (polytrauma, head injury).

The second main group of factors affecting adhesion formation represents those under the control of the surgeon. These include tendon handling, the tidiness of the repair, decisions regarding pulley preservation, and the important question of postoperative rehabilitation. All these areas have seen notable advances in the past decade. The result has been an important reduction in the severity of postoperative adhesions after tendon injury, and the consequent need for tenolysis. These are discussed below.

1.1.2 Treatment

Surgical Techniques to Minimize Adhesions

It has been known for many years that rough handling of the lacerated tendon in Zone 2 can worsen adhesion formation, by disrupting the smooth gliding surface of the tendon. For this reason it is important to handle the tendon gently, and grasp it only by the cut end. If the tendon has retracted into the palm, it should be retrieved with some sort of tendon carrier or passer, such as a narrow catheter. Any vincula that have survived the initial injury should be carefully preserved; indeed, if immediate repair is not possible then the finger should be splinted in wrist and finger flexion, to minimize the risk of rupturing any remaining vincula, until such time as surgical exploration can proceed. Active motion of the affected digit or digits should also be discouraged during this time.

A tidy repair, with the tendon ends coapted with slight bunching and normal rotational alignment, is critical to the smooth passage of the repaired tendon beneath any pulleys that are preserved. A tidy repair should also be a “low profile repair,” with the least possible amount of suture material on the anterior surface of the tendon. Knots and even suture loops are sources of friction that will initially score the overlying pulley (Fig. 1‑2), and later this scoring will lead to inflammation and adhesions.

Initially, pulleys were sometimes resected to allow room for the tendon repair, only to result in bowstringing and flexion contracture. This clinical problem will be discussed in another section of this chapter. To avoid this problem, for many years there was a strong emphasis among hand surgeons to preserve the pulleys, and even to close the sheath completely. Unfortunately, this too led to adhesions and limited tendon gliding, even with well-performed, low-profile, tidy repairs. The problem was that even the best repair could not reproduce the dimensions of an intact tendon, and even a cursory examination of the tendons as they slide under the A2 pulley will confirm that there is no room for any additional bulk at all. Thus, more recently there has been a push again for judicious pulley resection, including, if need be, all the A4 pulley and even part of the A2 pulley.2 Usually the amount of bowstringing after A4 excision is modest, because of the short segment affected (essentially, the length of P2), and the modest concave curvature of the palmar P2 surface. This is true even if, as is often the case with Zone 2 injury, the A3 pulley is not intact. In contrast, the P1 segment is longer, and its concavity deeper, resulting in more important bowing with A2 loss, especially if this is associated with A3 loss. Thus, it is important to preserve at least half of A2. An alternative strategy, which we prefer, is to resect (or excise rather than repair) one slip of the flexor digitorum superficialis (FDS), which creates adequate gliding space under the A2...