Chapter 47 Soft Tissue Coverage Around the Elbow

Introduction

Soft tissue coverage around the elbow deserves special attention as the skin and soft tissue envelope is thin and mobile, yet the bone beneath has prominences and sharp edges. Much like the tibia and knee but unlike at the thigh and hip, the elbow has a soft tissue layer that is in places only millimetres away from bone, joint, fracture or prosthesis. The relative thinness of this skin, paucity of padding, underlying irregular bone surfaces, necessity for marked mobility and stretch, and frequent exposure to trauma make the elbow similar to the knee with regard to soft tissue reconstructive requirements. Unlike other sites, these skin and soft tissue pre-requisites for maintenance or reconstruction of function mean flap reconstruction is usually the method of choice rather than skin grafts. Careful consideration of the soft tissues for the placement of incisions for exposure of the elbow can prevent future difficulties. But when wound problems do occur, knowledge of techniques for soft tissue cover of the elbow is invaluable.

This chapter aims to present the commoner defects around the elbow and some possible techniques for their reconstruction. Techniques for dealing with complications following soft tissue reconstruction are also discussed.

Background (elbow soft tissue requirements)

Most chapters on soft tissue cover centre on the concept of the reconstructive ladder. This concept instructs surgeons to use the most basic simple reconstructive method possible in order to achieve wound closure. Hence, split skin grafts are to be considered before full thickness grafts, and local flaps should be considered before distant or free flaps. This reconstructive ladder is fine for a simple wound in an area with no specialized function, but the elbow and its requirements are specialized.

The soft tissue cover of the elbow needs to be mobile, to allow joint movement and absorb contact and shear. It needs to be thin so as not to obstruct the full range of motion, or elbow positioning and posture. It needs to be robust and tolerant of trauma, particularly shear. As such, skin grafts are poor cover for the exposed portions of the elbow such as the olecranon or epicondyles, as grafts are intolerant of mobility, shear and trauma. For the elbow and its specialized needs the reconstructive ladder should be replaced by a reconstructive preference for thin cutaneous flaps, with muscle flaps and overlying skin graft reserved for massive defects or particular requirement for muscle such as white cell and antibiotic delivery in the management of infection or tendon reconstruction. Fortunately there are a plethora of potential flaps about the elbow that are available for transfer. The choice of flap depends on the character of the defect (such as location of the defect, the adjacent incisions or wounds, the size and complexity of the defect, and other requirements, for example – does the defect require dead space filling or is there a need for tendon reconstruction), patient factors (age, health, other injuries, rehabilitation constraints), and surgical factors such as the required exposure for simultaneous bone or other reconstruction, surgical experience and personal preference. Skin sensibility though advantageous is not essential as it is for cover of the sole of the foot.

Presentation, investigation and treatment options – indication for soft tissue cover (causes of defects and how to choose the method of soft tissue cover)

Trauma

Existing defects secondary to trauma are an obvious indication for soft tissue cover, especially if bone, joint or tendons are exposed. The decision for the need for a flap to achieve soft tissue cover should be made at the time of original debridement and stabilization, as subsequent decisions may be based on inadequate assessments with inadequate exposure, without general anaesthesia, and without displacement of any fibrinous material that may obscure the exposed bone, joint or tendon.

Even in cases where bone, joint or tendon are not exposed, such as small olecranon injuries, that could be left to heal by secondary intention, it may be preferable to close the defect by a local flap. This will avoid a tender and fragile scar with reduced pliability, compliance and mobility at a site vulnerable to minor trauma.

Trauma tends to produce soft tissue defects over the olecranon and, to a lesser extent, the antecubital fossa such as in a displaced open supracondylar fracture (Figs 47.1A,B). Traumatic defects in the ante-cubital fossa less obviously require flap coverage as bone and joint are covered by the thicker layer of soft tissue in this region, and the ability to close the defect by flexing the elbow. However, such an approach may compromise the ability to mobilize the elbow fully and result in an elbow flexion contracture. Most of these antecubital fossa wounds are often initially closed directly but may result in scar contracture necessitating a secondary release.

Figure 47.1 (A) Fracture dislocation creating an antecubital fossa wound. (B) Once reduced the wound, can be directly closed. (C) Small local rhomboid flap over olecranon, transferring skin from the slightly looser area distal and lateral to the olecranon.

Olecranon wounds frequently expose the fracture and fixation. Well-vascularized soft tissue cover should be achieved as rapidly as possible to minimize the risk of deep infection and infective non-union with osteomyelitis (Fig. 47.1C). In traumatic wounds in particular, there may be a role for flap coverage of the important or mobile structures with skin grafting of adjacent graftable areas.

Release of contractures

Elbow flexion contractures can be caused by scar and soft tissue contraction following burns or trauma. If the area of scarring is narrow or presents as a band or cord then excision of the cord and rearrangement of the surrounding skin by Z-plasties usually suffices to release the contracture. Should the area of scar contracture be extensive then an incisional release of the scar with correction of the contracture and elbow extension will produce a defect suitable for full thickness skin grafting or the interposition of a cutaneous flap.

Prosthetic elbow replacement wounds

Wound breakdown either acutely or some time after elbow replacement resulting in exposure of the prosthesis is a mandatory indication for good soft tissue cover. The optimal cover following debridement and sampling is with muscle flaps as these provide better vascularity, and hence antibiotic delivery than fasciocutaneous flaps, and are more conformable for dead space management in these often complicated wounds. Urgent treatment in this manner following exposure and stable fixation can make the difference between success and failure. Chronically infected and loose implants may require a two-stage process, with prosthetic removal followed by secondary reimplantation. Flap coverage in this circumstance tends to occur at the first stage, with careful elevation required for the reimplantation. Due to the size of defect, and the usually poor surrounding tissue in these cases, the muscle flaps are usually transferred from a distant site. Latissimus dorsi either pedicled or as a free transfer is commonly used, with free rectus abdominis or gracilis as good alternatives if a smaller surface area defect is encountered. In the case of a two-stage procedure, a myocutaneous flap that combines elements of muscle for infection control and skin for future surgery and exposure would be the optimal choice.

In some cases, the quality of the soft tissues mandates ‘prophylactic’ flap coverage at the time of the prosthesis implantation. It is better to consider it at the primary implant procedure than following inadvertent exposure.

Infection

Infected olecranon bursitis, if associated with skin necrosis, can require flap reconstruction. Local pedicled skin flaps (medial arm or lateral arm flaps) are usually appropriate, though local pedicled muscle flaps using flexor carpi ulnaris or brachioradialis that are then skin grafted can also be useful. The skin graft may not be as robust as flap skin but other determinants may lead one to choose these local muscle options. The tendon portion of brachioradialis or flexor carpi ulnaris can be used to reconstruct the triceps tendon or co-lateral ligaments. There is the possibility of transferring muscle and skin in the same flap with flexor carpi ulnaris if the skin defect is small. However, taking skin with muscle does introduce a limitation and increased level of complexity in the planning and inset of such a flap.

Occasionally chronically infected bursas lead to osteomyelitis of the olecranon and sub-cutaneous border of the ulna. Following debridement and deep tissue microbiological sampling these defects are best covered by muscle for dead space management, optimal antibiotic delivery and vascularity. These defects are frequently small and local muscle flaps of brachioradialis or flexor carpi ulnaris are ideal.

Autoimmune skin ulceration

Seemingly spontaneous skin breakdown can occur over the olecranon in patients with skin fragility secondary to autoimmune diseases such as dermatomyositis or rheumatoid arthritis. These are resistant to healing and may require excision and flap coverage.

Tumour excision

Soft tissue sarcomas around the elbow frequently require flap reconstruction following excision, as skin involvement is common. Fasciocutaneous flaps are favoured as they are more resistant to radiotherapy than muscle and skin graft. The design of the flaps must take into consideration the general principle of postoperative irradiation of the whole surgical field including any in-continuity flap donor site. The design of the donor site must therefore never extend past the surgical field such that circumferential limb radiotherapy becomes necessary. This would lead to marked limb morbidity and distal lymphoedema. Instead, radiation-free corridors should be preserved preferably along the course of a major neurovascular bundle. As a result of this unusual planning restraint, free fasciocutaneous flaps are commonly used in soft tissue reconstruction of this subgroup (Table 47.1).

Table 47.1 Considerations in choosing the type of reconstruction

Surgical techniques and rehabilitation

Direct closure

Direct closure is preferred where possible and where it does not hinder mobilization as determined by the orthopaedic component of the procedure. For example, a simple wound in the antecubital fossa, even with skin loss can be directly sutured by flexing the elbow, splinting the elbow for a couple of weeks then gradually regaining extension. However, such a period of immobilization in flexion would not be appropriate following an elbow arthrolysis.

Local muscle flaps

Brachioradialis

Brachioradialis can be used with or without the overlying skin due to skin perforators that traverse the muscle.¹ Only the skin overlying the muscle component of brachioradialis can be safely used. The muscle is supplied by a main artery and accompanying venae comitantes, arising from the radial recurrent artery or in 10% of cases directly from the brachial artery. The pedicle hilum inserts into the deep surface of brachioradialis approximately 10 cm distal to the humeral origin of the muscle, so this can be marked as the pivot point of the flap. This pedicle length of 3–4 cm allows a greater arc of rotation such that the flap can be used to cover the anterior aspect of the elbow, the lateral epicondyle and the olecranon and posterior aspect of the joint. The tendinous portion can be used to reconstruct the triceps.

For the usual muscle only flap, an incision is made over brachioradialis similar to the Henry’s approach to the radial nerve, and the skin elevated from the superficial surface of the muscle. The tendon is cut distally and the muscle elevated from distal to proximal. This reveals the pedicle and numerous minor vessels arising from the radial artery that can be gently bipolar diathermied, leaving the much larger 1.5 mm main vessel. The origin of the muscle can be left intact or divided. Division allows easier transposition with less tension. The flap can then be transposed and inset. If more length is needed in the pedicle the radial recurrent vessel can be gently dissected further. For a myocutaneous flap, a small skin paddle directly overlying the proximal two-thirds of the muscle can be incised and then elevation of the muscle proceeds as before. The donor site is sutured.

Extensor carpi radialis longus

As the extensor carpi radialis longus also obtains its main blood supply from the radial recurrent artery, it can be used either with brachioradialis to increase the volume and surface area of the required reconstruction, or as a muscle or myocutaneous flap separately.² The pedicle hilum inserts into the muscle 10 cm from the origin of the muscle or about 5 cm from the elbow flexion crease, forming the pivot point for transfer of the flap. This flap will cover the anterior, posterior or lateral elbow.

An incision is made directly over the extensor carpi radialis longus usually as an extension from the defect. The muscle is dissected from distal to proximal. The tendon is usually not harvested with the muscle unless needed for reconstruction of triceps or a collateral ligament. Compared to the easy dissection of brachioradialis, extensor carpi radialis longus is often adherent to extensor carpi radialis brevis. Minor vessels are divided but the main pedicle preserved. The origin of the muscle is divided preserving the origin of extensor carpi radialis brevis. The muscle is transposed and sutured. Skin graft is applied over the muscle and the donor site is closed directly. There is no functional loss from the use of extensor carpi radialis longus.

Flexor carpi ulnaris

This is another forearm muscle with a dominant vascular pedicle allowing its dissection and transfer, though flexor carpi ulnaris obtains its blood supply from the ulnar artery rather than the radial.³ The vessel originates 8 cm below the medial epicondyle marking the pivot point of the flap. Skin directly overlying the muscle can be raised with the muscle, supplied by cutaneous trans-muscular perforators. The flexor carpi ulnaris easily covers the antecubital fossa, the medial epicondyle and the medial aspect of the posterior elbow (Fig. 47.2).