Plaster cast, Pressure injury

Kay, an otherwise healthy and active 55-year-old woman, was diagnosed with a pressure sore on her lateral malleolus ankle following the application of a plaster cast. Find out how this could have been avoided.

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Event: Plaster cast.
Injury: Pressure injury.

Key points

  • Pressure injuries are a preventable pathology
  • Every patient complaint regarding a cast should be evaluated in a timely manner
  • It is better to remove a cast and find nothing amiss than to ignore the patient’s complaints and risk preventable pathology
  • Pressure-related complications increase with severe soft tissue swelling, particularly in a contained space such as a circumferential cast
  • Uneven bandaging technique, insufficient padding over bony prominences and the cast being too tight all contribute to the formation of pressure sores beneath a cast
  • Signs and symptoms of pressure sores:
    • Burning sensation or pain
    • Local heat
    • Unpleasant odour
    • Staining through cast
    • Pyrexia, in children

Case Study

Kay had been brought in by ambulance to the Emergency Department (ED) after she fell on steps. At initial presentation she was complaining of left leg pain and was unable to weight bear. There was tenderness around the ankle. There were no other injuries.

An X-ray of the tibia and fibula was reviewed by the ED and orthopaedic staff. Undisplaced fractures involving both malleoli of the ankle were noted. Kay’s ankle was very tender, so a plaster cast was advised. The cast was applied and Kay and her family were given routine advice to watch Kay’s toes for colour and movement and to ensure that the cast stayed dry. Kay was discharged with a plan for review at fracture clinic one week later.

Kay returned to the ED several days later, complaining of pain in the lateral side of her ankle. The cast was checked for integrity and an X-ray repeated. This showed no displacement of the fracture. She was reassured and advised to keep the leg elevated, and to keep the clinic appointment.

Kay was seen at the fracture clinic 12 days after the accident. The plaster was removed and a pressure area over the left lateral malleolus was found.

The orthopaedic registrar noted that the initial padding had been inadequate, and that there was a small ridge on the inside of the cast in that area. A new fibreglass cast was applied with additional padding. The plan was to see Kay in three weeks’; however, two weeks later she phoned to say the cast was ‘smelly’. Kay was seen at the clinic the next day. On removing the cast staff found that the pressure injury had worsened. A further cast was applied, and a window cut to allow regular dressings to the pressure injury.

Kay was referred to a wound care nurse practitioner, who diagnosed a Stage 3 pressure area with about 40% granulation at the base of the wound. There was a central core of undebrided necrotic tissue. A new dressing was applied and the window replaced over it, being held by tape. Kay was referred to the district nurse for follow-up wound care at home.

The wound care nurse lodged a claim for treatment injury. This was accepted as an injury caused by treatment for an already covered injury. ACC was able to contribute to the costs of Kay’s medical treatment and appropriate footwear during healing.

Expert Commentary

Helen Watkins, RGN, PG Cert
Clinical Nurse Specialist in Emergency Care, CENNZ, ENCAP

Pressure sores can be extremely painful and are entirely preventable.

In the ED, an acutely fractured limb should be placed in either a back slab cast or well split cast. Bear in mind that stockinette beneath a split cast should be left intact, as it can bunch beneath the cast, causing a ridge and subsequent pressure sore. Severe soft tissue swelling is to be expected following trauma, and pressure-related complications increase in a contained space such as a cylinder cast.

The application of the cast is a complex procedure, and should be undertaken or supervised by a trained practitioner with relevant assistance to support the limb, and the support should continue until the cast is set. This reduces limb movement during the procedure, which can lead to ridges in the cast. A ridge applies increased pressure to a small area, leading to a focus of decreased perfusion and subsequent pressure sore formation.

Post application, casting advice is best offered in both written and verbal formats, as the retention of verbal information is reduced in times of stress. These instructions can contribute to a reduction in the incidence of complications.

Complaints regarding cast discomfort should be acted on as soon as reported. Very young, old and mentally impaired clients often have difficulty clearly expressing pain, and their irritability should not be dismissed. Complications can occur within hours following a cast application. It is far more beneficial to remove a cast and discover nothing amiss than to treat a pressure sore at a later date. A stable fracture treated in a cast will not become unstable upon cast removal. In the first instance, an uncomfortable cast should be split and spread to relieve pressure. This can reduce pressure by as much as 60%. It should then be removed to inspect skin integrity.

In the case of a specific point of pain over a bony prominence, a window may be cut into the plaster to allow direct inspection and treatment, thus preventing whole-cast removal. In order to promote healing, the causative factor (i.e. the pressure) must be removed. A subsequent cast application encompassing a window will allow ongoing treatment of the pressure area. After each dressing change, the window should be replaced and secured with tape or a bandage to prevent weakening of the cast.

References

  • Boyd, A. S., Benjamin, H. J., Asplund, C. (2009). Principles of casting and splinting. American Family Physician. 79(1), 16-22
  • Halanski, M., Noonan, K. J. (2008). Cast and splint immobilisation: Complications. Journal of the Academy of Orthopaedic Surgeons. 16(1), 30-40
  • Hunter, I. A., Sarkar, R. (2011). Managing pressure sores. Surgery. 29(10), 518-522
  • Miles, S. (2004). Accountability in casting and splinting in the A&E department. Journal of Orthopaedic Nursing. 8, 114-116
  • Prior, M., Miles, S. (1999). Principles of casting. Journal of Orthopaedic Nursing. 3, 162-170

Claims information

Between 1 July 2005 and 31 June 2012 ACC received 1,155 claims relating to pressure injuries, of which 795 (69%) were accepted. There has been a steady increase in pressure injury claims nationally.

There were 65 pressure injury claims relating to plaster/fibreglass casts, of which 63 were accepted. The majority of the plaster/fibreglass-related pressure injury claims occurred in clients over 60 years of age. There were few differences in rates amongst men compared with women.

About this case study

This case study is based on information amalgamated from a number of claims. The name given to the patient is therefore not a real one.

The case studies are produced by ACC’s Treatment Injury Centre, to provide health professionals with:

  • an overview of the factors leading to treatment injury
  • expert commentary on how similar injuries might be avoided in the future.

The case studies are not intended as a guide to treatment injury cover. Send your feedback to: TI.info@acc.co.nz

How ACC can help your patients following treatment injury

Many patients may not require assistance following their treatment injury.

However, for those who need help and have an accepted ACC claim, a range of assistance is available, depending on the specific nature of the injury and the person’s circumstances. Help may include things like:

  • contributions towards treatment costs
  • weekly compensation for lost income (if there’s an inability to work because of the injury)
  • help at home, with things like housekeeping and childcare.

No help can be given until a claim is accepted, so it’s important to lodge a claim for a treatment injury as soon as possible after the incident, with relevant clinical information attached. This will ensure ACC is able to investigate, make a decision and, if covered, help your patient with their recovery.

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Published 19/12/2012

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