Date of Award


Degree Name

Doctor of Philosophy (PhD)

Schools and Centres

Nursing and Midwifery

First Supervisor

Leanne Monterosso

Second Supervisor

Max Bulsara


Total hip and knee replacement operations are one of the most commonly performed orthopaedic procedures in Australia. It is estimated however that up to 65% of patients will experience some degree of opioid-related bowel dysfunction in the post operative period. Often considered a mild and selflimiting problem, constipation can lead to significant morbidity and occasional mortality. Several clinical incidents and a lack of robust evidence to guide bowel management in this cohort was the impetus for this study.

This cluster randomised study sought to evaluate the Murdoch Bowel Protocol©, a simple nursing intervention based on the administration of polyethylene glycol (Movicol®) titrated to Bristol Stool Chart type. The Neuman Systems Model was the theoretical framework used to guide this study. The hypothesis was that patients who undergo a knee or hip replacement and receive the study bowel protocol will experience a statistically significant reduction in time taken to return to normal bowel function compared with patients who receive standard bowel management.

Three hundred and thirty one patients were recruited across seven hospitals in two Australian states over a 13 month period. Five hospitals were randomised as controls, two hospitals as interventions. Data was collected from all patients at three intervals: pre-admission, during admission and post discharge. Control participants (n = 171) received post operative bowel management as per that hospital or doctors usual regime whilst intervention participants (n = 160) received post operative bowel management as per the Murdoch Bowel Protocol©.

Inferential statistics confirmed several highly statistically significant results as well as clinically significant outcomes. Patients treated with the Murdoch Bowel Protocol© returned to normal bowel function more quickly than those xi treated with ad hoc post operative bowel regimes (p = 0.000). In addition intervention patients were more than seven times more likely than controls to return to normal bowel function by day five post operatively (p = 0.000). Age, gender and length of pre-operative fasting were not found to influence this result. Type of anaesthetic was significant with patients who received combined regional and general anaesthesia returning to normal bowel function around two days less than those who received a general anaesthetic ( p = 0.014). Type of operation was also significant with total knee replacement patients taking on average one extra day to return to normal bowel function (p = 0.027). Use of the generalised linear mixed model confirmed no cluster effect. These results confirm and support the study hypothesis.

These results support practice changes not only for hip and knee replacement patients but for other patient groups who experience opioid induced bowel dysfunction. Further research will determine whether the protocol is as efficacious in these patient groups.

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