Total Hip Arthroplasty (THA) is currently one of the most successful procedures in orthopaedics. Over the last 40 years, postoperative care has significantly evolved. Initially, the standard procedure following THA was that patients were required to stay in the hospital to recover for 2.5 to 3 weeks. However, with the implementation of less invasive techniques, coupled with early weight bearing and more comprehensive postoperative rehabilitation protocols, inpatient stays have drastically decreased on average to 2 to 3 days. A new, minimally invasive surgical (MIS) technique has led to an even larger decrease in hospital stays, culminating in a same day discharge. The possibility of early mobilization, combined with an increasing push from patients to accelerate recovery and return to activities, have led to the implementation of outpatient THA in select patients. For same day discharge to succeed, extensive preoperative and perioperative care must accompany the procedure. Furthermore, more aggressive rehabilitation and improved pain control is crucial for successful outpatient THA. For younger patients that need to return to work as early as possible, a quicker recovery time is essential. Perfecting outpatient THA is a crucial step towards achieving these requirements.

There are 4 major components to a successful THA: pain relief, functional recovery, patient satisfaction and durable reconstruction. Outpatient THA is a fairly new concept in arthroplasty, and patient satisfaction has not been properly assessed following this new THA protocol. Satisfaction in accordance with THA refers to a patient achieving their functional and pain expectations. A similar study evaluating patient satisfaction of a randomized control trial (RCT) of inpatient versus outpatient anterior cruciate ligament (ACL) reconstructions reported that outpatient satisfaction following surgery is higher than inpatient satisfaction. Although this is a different procedure, it would seem outpatient ACL reconstruction and outpatient THA has similar pain levels, safety and patient satisfaction. The goal with outpatient surgery with regards to satisfaction is providing patients with relief of their anxiety, while allowing them earlier control of their independence. Potential advantages of outpatient surgery include that patients are permitted to recover in a secure, private and comfortable home environment, while surgeons will improve efficiency and time management with the decreased responsibilities of having to visit their inpatients.

In addition to the potential satisfaction benefit, outpatient THA is a potential source of cost savings for both the patient and the hospital. Numerous efforts by hospitals have been made to decrease costs and increase available beds for additional patients. A previous study investigating the financial effects of outpatient THA found that the average hospital bill for outpatients was $4000 less than for the inpatients. Including preoperative physical therapy and home healthcare, the total charges for outpatients was $2500 less than inpatients. A similar study demonstrated that select individuals can successfully undergo THA in an outpatient setting with no increase in complications, while also receiving a substantial savings to the patient and the healthcare system. By reducing costs and increasing healthcare staff availability, hospitals can allocate more money to areas in need of funding, while wait times can drastically reduce for future patients.

The most important part of preoperative care for a successful outpatient THA is giving the patient appropriate goals and expectations. Patients should be educated by the anaesthesiology team, the physical and occupational therapist, the surgeon, the nurses, and anyone else involved in the surgery. Patients are required to attend classes explaining the various aspects of the operative experience, as well as discharge goals and techniques for postoperative home rehabilitation. Furthermore, functional and symptomatic goals need to be clearly defined. In these educational sessions, pain management strategies are one of the main focuses. To have a successful same day discharge, patients must be well versed in pain management and proper rehabilitation strategies. Before the preoperative class, all patients are instructed to practice certain skills, such as bed transfer, cane/crutches use and gait training. Potential complications are discussed so that the patient is reassured with what is normally supposed to happen following surgery. The goal of preoperative care is that the patient has a defined set of goals and expectations for their surgery, medications, and rehabilitation.

For outpatient THA surgery, it is preferred to perform the surgery in the morning to facilitate same day discharge. Immediately following surgery, the primary goals are to treat pain, nausea and hypovolemia. Prior to symptoms arriving, these issues have to be dealt with using the proper fluids and medications. Physical therapy is usually initiated 3 to 4 hours following surgery. The combination of this early rehabilitation program, combined with the minimally invasive surgical technique is vital to the rapid recovery process. Home physical therapy should begin immediately, with a focus on ambulation. The patient is then asked for a follow-up visit within 1 week of the surgery to make sure all of the patient's goals have been met.

The primary concern with outpatient THA is safety of the patient. There are also concerns including emergency room readmissions in patients who have difficulty once home in the immediate postoperative period. Furthermore, some patients will require transfer to an inpatient facility when they are experiencing a delayed recovery after surgery.

Anecdotal data was collected prior to the start of this research project. Since there was a clinical practice change, informal conversations with outpatient THA demonstrated that 10/11 patients would have outpatient surgery again, and 9/11 would recommend outpatient THA surgery to others. These encouraging findings are an important justification for performing the present study.

Although previous THA outpatient studies have demonstrated successful results, it is imperative to complete a RCT to diminish any bias associated with these findings. In the absence of high quality comparative evidence, the success in same day discharge THA may be a result of selection bias, since previous research is largely driven by observational studies of highly selected populations. This would severely decrease the generalizability of previous studies. To our knowledge, this will be the first level one study that will investigate the cost, early complications and patient satisfaction associated with outpatient THA in a pragmatic selection of patients. This study will answer important questions on how to best treat patients undergoing THA, and whether an earlier discharge following surgery affects patient outcomes.

A retrospective analysis of over 50,000 THA and TKA procedures found no differences in 30-day major complications or readmissions among patients with a zero to two-day hospital stay compared to those discharged on day three or four postoperative. The rate of serious adverse events in the inpatient group is expected to be greater than five percent. To define a non-inferiority margin we agreed that no more than a five percent increase in the risk of serious adverse event (RD ≥ 6% favoring inpatient care) was acceptable. If the risk in the inpatient group ranges between five to eight percent and there is truly no difference in risk of serious adverse event between the groups, then a maximum of 506 patients are required to be 80% certain that the upper limit of a one-sided 95% confidence interval will exclude a difference in favour of the inpatient group of more than six percent. Given that the primary outcome is being measured at 3-months postoperative, we anticipate a low lost-to-follow-up rate. Previous studies conducted at the study site in similar patients demonstrate loss to follow up rates less than one percent for the first 3 months. Therefore, to account for a potential one percent dropout rate we inflated our sample size to 511.