VOL: 98, ISSUE: 08, PAGE NO: 62
Lilian Bradley, SRN, ONC, PGDip, is lecturer/practitioner in tissue viability, Ulster Community and Hospitals Trust and Queens University, Belfast
Pre-tibial lacerations or skin tears are acute wounds caused by trauma. However, they frequently take on the characteristics of chronic wounds and become difficult to heal. The reasons for this include the age of the patient, other co-existent disease processes and the fact that the pre-tibial region is naturally poorly vascularised.
Normal skin integrity can be jeopardised or compromised by several factors, including chemical, allergic, vascular or mechanical trauma - the latter resulting from force, pressure, shear, stripping or friction. Skin stripping or tearing occurs principally on the extremities of older adults and is a separation of the epidermis from the dermis - partial thickness wound - or a separation of both the epidermis and the dermis from the underlying structures - full thickness wound (Payne and Martin, 1993).
The majority of skin tears (80%) occur in the upper extremities in the dependent patient and are thought to be due to frequent handling, while 20% of skin tears occur on the lower extremities, mainly in the independent patient as a result of trauma (McGough-Csarny and Kopac, 1998).
Patients with pre-tibial lacerations usually present at an A&E department, minor injury unit or GP surgery. A few will try to manage at home either by themselves or with the help of a carer and only present for medical help when problems arise, such as infection or non-healing.
As with all wounds, early treatment choices may well determine the outcome in terms of time to healing, minimising the risk of infection and, most importantly, functional and cosmetic outcomes (Dickerson et al, 1999).
It is important to assess the health of the whole person and not to focus solely on the injury (Dearden et al, 2001a) (Box 1). Current medications will give useful clues to the patient’s health status and will indicate disease processes that may delay healing, such as diabetes, peripheral vascular disease, venous hypertension, cardiac failure or renal impairment. The use of anticoagulants will alert the practitioner to the increased risk of bleeding and haematoma formation.
The time and circumstances of the injury are important, as the resultant flap may remain viable for up to six hours post-injury. Viability is usually determined by colour - a dark flap or one with a dusky blue edge is likely to be unviable.
It is also important to ascertain how the injury occurred. Frequent falls or bumps may indicate deteriorating eyesight, a problem with balance or simply be due to a cluttered or unsafe environment.
If the injury occurred in a dirty environment, the risk of infection and the general threat of tetanus will be increased, and a delay of more than six hours may increase the likelihood of infection, especially if the wound is closed (Berk et al, 1988).
The site of the injury will usually be in the distal third of the pre-tibial region (Panting and Blake, 1976), which receives its blood supply in a longitudinal pattern from the perforators of the popliteal, peroneal and anterior tibial arteries. Transverse lacerations will, therefore, further interrupt the supply. The flap may be attached distally, proximally, laterally or medially (Jones and Sanders, 1985) or it may be a linear laceration.
Wound assessment should ascertain the following:
- Maximum length;
- Maximum width;
- Partial or full thickness;
- Underlying structures;
- Type and level of exudate;
- Bleeding points;
- Haematoma formation;
- Viability and condition of flap.
Any bleeding should be controlled by localised pressure or limb elevation and medical help sought. If the patient is in pain this should be addressed with suitable analgesia and, where possible, anxiety should be allayed and treatment options discussed with the patient and carers, particularly if in-patient treatment is required.
Traumatic wounds are generally considered to be contaminated. The aim of cleansing is to remove debris, devitalised skin and haematoma, as their presence will delay healing by prolonging the inflammatory response and increasing the risk of infection.
It is generally accepted that 0.9% saline warmed to 37oC is the solution of choice for wound cleansing and that antiseptics have little value, since they are not in contact with the wound bed long enough to have any effect on residual bacteria (Brennan and Leaper, 1985).
Since swabbing and rubbing over the wound bed may cause further tissue damage or redistribute solid contaminates, irrigation with or without pressure, depending on the absence or presence of foreign bodies, is recommended.
While irrigation will remove debris and contaminants, devitalised tissue is best removed using sharp debridement. This will generally be painless, but if the patient is nervous, or more extensive debridement is required, a local anaesthetic such as 2% lignocaine may be beneficial. Theoretically it may be beneficial to remove any adipose tissue from the flap, since this is avascular and may prevent attachment of the flap to the underlying subcutaneous tissue (Haiart et al, 1990).
The presence of a haematoma in a wound will act as a foreign body and provide an ideal medium for bacteria to flourish (Angel et al, 1986). It will also cause tension within the wound and pressure on underlying healthy tissue structures. Evacuation of the haematoma is therefore recommended. This should be carried out with caution, as removal could activate further bleeding, particularly in the anticoagulated patient. If bleeding does occur, localised pressure may be sufficient to arrest it; if it does not, the possibility of an arterial injury should be considered before closure is attempted (Singer et al, 1998).
In patients who present with a pre-tibial haematoma and intact skin there is merit in leaving the skin intact and allowing the haematoma to resolve over time. The patient should be advised to return to the A&E department, should the haematoma increase.
Traditionally, partial thickness skin flaps are gently unfurled and the skin edges apposed with undue tension (Cockerill and Sweet, 1993; Crawford and Gipson, 1977). Rough handling with forceps and the application of tension may damage an already poorly vascularised flap and, since in most elderly patients the elasticity of the skin is reduced, complete apposition will not be achieved. For this reason the use of tissue adhesives - such as cyanoacrylates - although painless and quick to apply is not suitable, as adhesive, when applied directly to a wound bed, will prevent epithelialisation and increase the risk of foreign body reaction (Quinn et al, 1997). However, cyanoacrylates may be suitable for linear tears.
Sutures versus sterile closure strips
It is generally accepted that in the older patient the use of adhesive tapes to secure the flap (Fig 1) is preferable to sutures because of the fragility of the skin (Moulton and Yates, 1999) and the increased risk of infection (Sutton and Pritty, 1985; Salasche, 1986).
However, Silk et al (2001) used an innovative method of suturing by applying sterile closure strips parallel to and about 1cm from the wound edges and suturing through the sterile closure strips. This was postulated to have the effect of closing the gap and stabilising it without risk to the healthy skin. Of the 112 patients in the trial, none required skin grafting, and the average healing time was reported as 26 days. While this is impressive, Silk was an experienced A&E doctor who carefully selected those patients who presented early and therefore had viable flaps. He was also skilled in this technique of flap repair.
If sterile closure strips alone are used these should be applied with undue tension and with space between the tapes to allow for free drainage of exudate and blood, otherwise fluid collects under the flap, reducing the likelihood of the flap taking.
A possible alternative to sterile closure strips may be that, once the flap has been unfurled, a silicone-based dressing such as Mepitel can be used to secure it. This dressing is thought to be non-adherent to the wound bed but gently adherent to skin and is atraumatic on removal (Pudner, 2001). It also allows for drainage of exudate or blood and can be left in place at the first dressing change, with only the secondary dressing being changed. However, a disadvantage of this is that it does not allow for direct examination of the flap at the first dressing change.
A variety of dressings have been used in the conservative treatment of pre-tibial lacerations, ranging from paraffin gauze (Sutton and Pritty, 1985) to zinc paste bandages (Crawford and Gipson, 1977). However, there are few studies comparing dressing types in these wounds.
It is well documented that paraffin gauze dressings, although ensuring a moist wound bed, cause considerable pain and trauma on removal (Thomas, 1997; Handfield-Jones et al, 1988). This elicits an inflammatory response and delays wound healing; therefore their use in this type of wound should be avoided.
Zinc paste bandages have been used for centuries, mainly in the treatment of skin conditions such as eczema and in the management of venous ulcers (Eagle, 1999; Williams, 1999). The main ingredients of these bandages are zinc oxide, glycerine and water (Anderson, 1995). Zinc is thought to promote wound healing by reducing free radical activity, strengthening collagen already depleted in the skin of the older patient, improving cell mitosis - which is essential for the movement of epithelial cells across a wound bed - and inhibiting bacterial growth (Dickerson, 1993).
The research base to support the use of topical zinc oxide in wound healing is shaky, since much of the work has been carried out on animal models (Tarnow et al, 1994; Argren et al, 1991) and therefore cannot be easily extrapolated to humans. It could be argued that, since skin contains 20% of the body’s zinc stores (Wells, 1994), skin loss will therefore deplete zinc levels, although the skin lost in pre-tibial lacerations will account for only a small percentage of total body skin. Furthermore, it is not known what percentage of zinc is absorbed through the skin, and the addition of oral zinc is thought to benefit only patients whose zinc depletion has been demonstrated (Reed and Clarke, 1985; Mazzota, 1994).
What, then, is the rationale for the application of zinc paste bandages in the management of pre-tibial lacerations? In a randomised controlled trial Stacey et al (1997) demonstrated a statistically significant increase in venous leg ulcer-healing in favour of a zinc oxide-impregnated non-stretch cotton bandage applied as a bandage toe to knee and used as a primary contact layer. This was compared to an alginate dressing as the primary contact layer and a zinc oxide-impregnated stockinette toe to knee. Two types of compression bandages were used, with no difference in sub-bandage pressures being reported.
It could be postulated that the zinc oxide-impregnated bandage acted as a short-stretch compression bandage, forming a rigid sheath around the leg, thus aiding venous return. Therefore it may be that the benefit of such a bandage is from the compression effect rather than the zinc content. Added to this, there is a risk of pressure necrosis (Fig 2) as the bandage dries and shrinks (Eagle, 1999); therefore the spiral method of application should be avoided and the bandage applied in a pleated or criss-cross course up the leg.
Caution should also be exercised when these types of bandages are applied as a primary contact layer, as they shed fibres in the wound bed. These can act as a foreign body, eliciting an inflammatory response and delaying wound healing. A suitable primary dressing might be Mepitel or N/A Ultra, which would allow the passage of zinc from the bandage to the wound bed without the risk of shedding fibres. It should also be remembered that some patients may display sensitivity to some constituents of paste bandages. Dearden et al (2001b) suggest a more novel use of a zinc bandage in that it holds the skin flap in place.
Another type of dressing frequently used in the management of pre-tibial lacerations is the povidone iodine-impregnated dressing. This type of dressing has been shown to reduce bacterial numbers on the surface of burns (Zellner and Bugyi, 1985) but is known to become inactivated in the presence of exudate - signified when the orange dressing becomes white.
Since pre-tibial lacerations are new wounds, a degree of wound exudate would be expected as part of the inflammatory response. The literature to provide an evidence base for the use of antibacterial dressings is not helpful, as studies have been either in vitro or used animals (Brennan and Leaper, 1985; Lawrence, 1998).
Lawrence (1998), using a wound model and horse serum, concluded that there was some antibacterial - although short-lived -prophylactic benefit but cautioned against the extrapolation of this finding to actual wounds. The more frequent application of the povidone iodine-impregnated dressing on bacterial levels was not measured and would not be practical in real-life situations.
As alluded to earlier, the time lapse from injury to initial treatment is crucial in traumatic wounds. Delay in seeking help will almost certainly ensure that contaminatory bacteria are already present in the wound bed. This challenges the ritualistic practice of leaving pre-tibial lacerations for 10 days before the first dressing change, as clinical infection may well present before this time frame (Fig 3).
Excision and grafting of flaps
Excision and regrafting of the existing flap has been shown to reduce healing rates. In a study of 30 patients, Foroughi and Nouri (1990) demonstrated a healing rate of 31 days when the flap was excised without local anaesthetic and replaced on the wound bed.
Grant (1993) excised the flap at its junction within three hours of injury and, using local anaesthesia, scraped off the dermal fat, cut the flap into small 3-5cm pieces and laid it dermal side down on the wound bed, in much the same way as a pinch graft. Healing was achieved in 35 days. The benefit of this treatment is that no second wound was created through a donor site, and the patients did not need to be hospitalised.
In a review of the literature, Bradley (2001) concluded that grafts from a donor site gave even better healing rates. However, these necessitated a general anaesthetic, created a second wound and required hospitalisation, which can be daunting and disorientating to some elderly patients.
If a split skin graft is required, the use of vacuum-assisted closure on a large area of skin loss ensures an improved blood supply in preparation for grafting (Fig 4). It also is thought to reduce the bacterial load, another common cause of graft failure (Morykwas and Argenta, 1997).
The role of compression bandaging
Compression therapy, whether graduated or uniform, is a feature of many of the studies mentioned. However, it has not been credited as having influenced healing rates, nor have sub-bandage pressures been measured.
The mode of action of graduated compression is thought to be a reduction in hydrostatic pressure, reducing oedema and allowing nutrients to pass through capillaries to the wound site, raising PO2 levels. In a study on healthy young adults Mayrovitz (1998) demonstrated a positive influence of graduated compression on arterial flow in the lower limb, with an increase in tissue oxygen perfusion. This is thought to favour collagen synthesis and fibroblast differentiation, which should enhance wound healing and improve the cosmetic result (Hunt and Pai, 1972).
However, Mayrovitz also demonstrated a reduction in distal perfusion and, since pre-tibial injuries are frequently seen in elderly people, it is of the utmost importance to rule out any significant degree of peripheral vascular disease before the application of any compression bandaging. This can be established through a clinical history and the use of Doppler ultrasound to determine the ankle brachial pressure index (ABPI) (Vowden and Vowden, 1996).
In busy A&E departments, minor injury units or treatment rooms there is not always time to measure the ABPI. In such cases the use of light compression in the form of an Elastocrepe bandage may be worth considering in the interim, provided the patient does not have a history of intermittent claudication or night pain, is a non-smoker, does not have diabetes and has no clinical signs of peripheral vascular disease. This should be applied spirally from toe to knee and at full stretch. If compression is used, bony prominences should be protected with wool padding.
Following initial treatment the patient can be referred back to the primary care team. If there is a local leg ulcer clinic this may be a good point of referral, as the nurses will be experienced in vascular assessment using Doppler ultrasound. Certainly patients with evidence of chronic venous hypertension and a history of venous ulcers would benefit from further assessment and higher levels of compression if their arterial status permits this.
Recall for the first dressing change should be around day five. This will allow inspection of the wound bed for infection, assessment of the ‘take’ of the flap and removal of any devitalised tissue or haematoma remnants. Where devitalised tissue is not ready for removal a hydrogel may be applied to assist autolysis. If adhesive tapes have been used these should be left in situ for at least 10 days, provided they are still adherent and have not lifted or been dislodged. Care should be exercised when removing the tapes, as separation of the epidermis and dermis can occur, especially in very fragile or thin skin (Jones and Millman, 1990).
At this stage exudate levels will have reduced, as the inflammatory phase of wound healing should have passed. A simple silicone-based non-adherent dressing applied with wool padding and compression bandaging should suffice. Weekly dressings may then be adequate, but this will be dictated by the number of days to exudate strike-through. While normal daily activity should be encouraged, the patient should also be encouraged to elevate the limb when seated and to plantar-flex and dorsi-flex the ankle to optimise venous return.
If clinical signs of infection are present this should be treated systemically.
As with all patients presenting with traumatic wounds, a full assessment will determine treatment choices (Box 1).
The aim of treatment is to minimise the risk of infection, promote healing and obtain the best cosmetic result with the least inconvenience to the patient. Conservative management does appear to lead to protracted healing rates but does not have the added disadvantage of a troublesome donor site or hospitalisation. There is little guidance in the literature on dressing options, but the concept of moist wound healing, protection of the wound bed and minimal trauma to the patient should always govern choice.
Clearly there is scope for more randomised controlled trials in the conservative management of patients with pre-tibial lacerations and, since the number of patients presenting with this condition is relatively small, multi-centre trials will be necessary. In the meantime the provision of locally acceptable guidelines may direct the practitioner in making the optimum choices. However, the decision whether or not to treat conservatively should always be made in consultation with the patient and carer and only after treatment options have been outlined and the advantages and disadvantages explained.