The Direct Anterior Approach (DAA) is a common way to perform total hip arthroplasty. There are two main techniques to perform total hip replacement through the anterior approach. The first method is the "on-table" method, which uses a specialized surgical table, called a traction table. This table involves placing both feet in specialized boots that are then hooked up to the table, and allows for positioning of the operative leg with aid of the table. The major limitations associated with the traction table are the need for two additional staff members and the purchase of said table. The second method is the "off-table" method. In this method the patient is placed on a standard operating room table and the operative leg is manually positioned by the surgeon during the procedure . This obviates the need for the additional staff members or purchase of a specialized table. Both the "on-table" and "off-table" techniques are routinely used both worldwide and by our joint replacement specialists at Carilion Clinic. This study will aim to compare the efficiency and efficacy of performing the DAA for total hip arthroplasty utilizing either the "on-table" or "off- table" technique. Patients will be randomized to receive their total hip arthroplasty with either the "on- table" or "off-table" method.

BACKGROUND: The Direct Anterior Approach (DAA) for total hip arthroplasty (THA) has become increasingly popular in the US over the last decade (Berry & Bozic, 2010). Major limitations of the DAA with traction table include the need for an additional surgeon's assistant, a traction table operator, and the purchase of said table. To counter these limitations, some surgeons advocate for the performing the DAA with a conventional operating room table {Cohen, 2017;Molenaers, 2017}. However to date, there are no studies directly comparing the efficiency and efficacy of these two techniques for DAA.

OBJECTIVE: Currently, it is unclear which surgical technique is more efficient and effective for total hip arthroplasties (THA). We hypothesize that there will be an increase in efficiency as measured by time when performing a standard operating table (Off-Table) DAA THA when compared to a purpose built traction table (On-Table) DAA THA. In addition, there will be less pain and faster functional recovery in the early post-operative period for patients who underwent an "Off-Table" DAA THA when compared to an "On-Table" DAA THA.

SPECIFIC AIMS: 1) Determine whether there is a difference in operating room efficiency between surgeries after a THA via DAA with a standard OR table versus a purpose-built traction table; 2) examine whether there is a difference in early post-operative pain and clinical outcomes when comparing patients who underwent a THA via the DAA with a standard OR table versus a purpose built traction table. 3) report differences in complication rates between those two.

METHODS: This is a prospective randomized clinical trial that will evaluate adult patients admitted to Carilion Clinic undergoing primary unilateral total hip arthroplasty. Off and on table DAA procedures will be performed by a single surgeon with multiple years of training and experience in both. Cluster randomization will be performed where patients will be randomized through scheduling. Demographic data will be collected. Operative records will be used to record operative times for each approach. Radiographs to assess implant positioning on postoperative day 0. The primary outcome variables are intra-operative data such as time the patient enters the operating room, time of incision, time of dressing application, exit room time, implants used, operative report. For secondary outcome variables, we will assess at 2 and 6 week follow ups routine Patient-Reported Outcome Measures including narcotic utilization based on pill count and MEq, and the PROMIS and HOOS, JR. measures.

EXPECTED OUTCOMES: We expect that the Off-table DAA technique will be associated with faster set up, surgical time, and overall room time when compared to the On-table approach. Additionally, we expect less early post-operative pain in the groin, knee and ankle. We expect that the patient report outcome measures at 2 and 6 weeks post-op for the off-table DAA group will be equivalent or better than the on-table DAA group. Finally we expect no difference in complication rate.

Inclusion Criteria:

• All patients undergoing primary unilateral THA
• Patient 18 years of age and older
• Patients who are able to provide consent

Exclusion Criteria:

• Bilateral procedure
• Non-Primary arthroplasty
• Prior non-arthroplasty operation requiring removal of hardware
• Inability to have spinal anesthesia (blood thinners)
• BMI > 40
• Active Smoking
• HbA1c > 8.0
• Failure to meet medical clearance
• Pregnant women per standard of care

No current plan to do so.

BLINDING: none It is impossible to blind the surgeon to the arm as the techniques and instruments required for on-table vs off-table are substantially different. All subjects will be patients of Dr. Owen and he is the only operating surgeon for this study.

The patient will see the beds when they are rolled into the operating room and are positioned. Thorough informed consent will make it apparent which table they are using.