Facilitating effective decision-making in healthcare is one of the key roles health professionals perform. However, a patient’s decision-making can often be complicated by the varying opinions presented to them. While some healthcare decisions have a preferred treatment option based on a health professionals’ clinical practice and knowledge of the best available evidence, decision-making for others are less clear. These decisions are deemed “preference-sensitive” and require a patient to consider their own personal needs, goals of treatment and expectations of the outcomes following treatment. One “preference-sensitive” decision is that surrounding the treatment of late stage osteoarthritis (OA) with surgery. Total knee arthroplasty (TKA) is the most common surgery recommended, and is regarded as an effective treatment to manage pain and functional deficits. However, there is a lack of consensus on the exact concurrent criteria that should be applied when recommending TKA to patients. Thus, encouraging patients to more closely consider their unique requirements of treatment and the realistic outcomes of this surgery may lead to improved decision-making. One effective way to facilitate this process and appropriately communicate this information is through patient-facing decision aids. This thesis explored the complexity of the decision-making process, and offers important contributions to the literature regarding the decision-making of patients considering TKA and the considerations health professionals integrate into their decision-making when recommending TKA to patients suffering from OA. Importantly, this thesis highlights areas of improvement in the decision-making process and identified that a co-designed patient decision aid was able to improve the decision quality of patients considering TKA. Ultimately, the findings of this thesis suggest an improved process through which patients can make evidence-informed decisions on whether to elect to undergo TKA.