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Pros and Cons of Bilateral Simultaneous Hip Replacement

Hip osteoarthritis is a debilitating joint disease that affects daily activities. Total hip arthroplasty (THA) is a common orthopedic surgery that can decrease pain and improve joint function of patients suffering from hip osteoarthritis. THA is also performed for other hip joint disorders such as juvenile arthritis, avascular necrosis, and hip fracture. Over the past decade, the number of THA procedures has increased and is estimated to rise to 635,000 by 2030.[1]

Historically, a patient requiring the replacement of both hips underwent two separate surgeries. However, in 1971 Charnley et al. presented simultaneous bilateral hip arthroplasty.[1] This procedure replaces the joints of both hips at the same time. Since then, multiple studies have examined the safety and effectiveness of having both hips replaced simultaneously.

How is Bilateral/Simultaneous Hip Replacement Performed?

The hip is a ball-and-socket joint formed by two bones: the femur and the pelvis. The head (or ball) of the femur rests in the socket of the pelvis, also called the acetabulum. During THA, the surgeon removes the damaged cartilage and bone from the hip joint and replaces them with prosthetic pieces.[2]

  • Femur

    the surgeon removes the femoral head and replaces it with a metal stem implanted into the shaft of the femur. A metal or ceramic ball is placed at the end of the stem to act as the ball joint of the hip.
  • Pelvis

    the surgeon removes the cartilage in the acetabulum and replaces it with a metal socket. The socket sometimes requires screws or cement to hold it in place. Then, a metal, plastic, or ceramic liner is placed between the new socket and ball to help allow for smooth joint gliding.

This procedure is performed on each hip during the same surgery for a bilateral simultaneous THA. Operation time is affected by the surgical approach, surgeon expertise, type of anesthesia, and patient condition.[1] Usually, a unilateral (single-sided) THA takes 1-2 hours.

Patient Selection for Bilateral Simultaneous THA

There are no absolute restrictions for patient selection for total hip arthroplasty. Most surgeons use the American Society of Anesthesiologists (ASA) Physical Status Classification System to determine if a patient is appropriate for surgery. There are six levels of classification using the ASA:[3]

  • ASA 1: a patient with no chronic illnesses, a normal body mass index (BMI), non-smoker, and minimal or no alcohol use
  • ASA 2: a patient with mild chronic illness without significant functional limitations; examples include: current smoker, drinks alcohol socially, pregnant, obese with BMI between 30-40, well-controlled diabetes mellitus, and mild lung disease
  • ASA 3: a patient with substantial functional limitations due to one or more moderate chronic diseases; examples include: poorly controlled diabetes mellitus, hypertension, or COPD, morbid obesity with BMI over 40, alcohol dependence, kidney disease requiring dialysis, and history of heart attack or stroke
  • ASA 4: a patient with severe disease that is a persistent danger to life
  • ASA 5: a patient at the point of death who is not likely to survive without the operation
  • ASA 6: a person who has been declared brain-dead and is awaiting surgery to acquire organs for donation

Patients selected for THA surgery are usually classified as 1, 2, or 3. Most studies looking at simultaneous bilateral THA versus staged bilateral THA (each hip is replaced during separate surgeries) find that patients chosen for simultaneous surgeries are younger (age 60.6 vs 65.5)[4] with a lower ASA score of 1-2.[5]

Advantages of Bilateral Simultaneous THA

Less time in surgery:

Zhou et al. found that the mean operation time for single-side THA was 145 minutes, versus 220 minutes for staged bilateral THA. However, for simultaneous bilateral THA, they found the mean operation time was 176 minutes. Zhou also noted that overweight patients had longer operative times, whether unilateral or bilateral.[6]

Decreased hospital stay:

Ramezani et al. reviewed several studies on staged vs. simultaneous bilateral THA and found that the simultaneous bilateral THA group had a mean hospital stay of 4.8 days fewer than the staged group.[1]

Lower cost:

Yakkanti et al. analyzed several reports and found that the average cost for hospitalization for a simultaneous bilateral THA was $25,347, while two separate hospitalizations cost $33,514. The Fewer days in the hospital, less operating room time, and fewer complications results in a smaller hospital bill.[7]

Faster recovery:

Achieving ideal functional outcomes after THA is essential. The following standards are used to assess function after THA: the ability to stand upright, the ability to walk, and the ability to sit down in a chair and then return to standing. A comparison of patients who had undergone either unilateral THA or simultaneous bilateral THA showed:

  • Those who underwent unilateral THA had weight-bearing asymmetry (the inability to stand up straight), postural instability, and a greater risk of falling. These findings may be due to leg length discrepancies after surgery.
  • Patients who underwent simultaneous bilateral THA had better balance with body weight distribution. As compared to the unilateral group, they also had similar functional mobility, reported pain levels, and fear of movement.[8]

As patients undergoing bilateral simultaneous THA recover at the same rate as those having unilateral THA, they will be back to normal activities and work faster without the need to have a second procedure.

Risks for Bilateral Simultaneous THA


Both general anesthesia and spinal anesthesia are regularly used for THA. The usual side effects of anesthesia are:

  • nausea and vomiting caused by medications
  • sore throat from being intubated
  • postoperative delirium that may last up to a week for older patients
  • shivering and chills as body temperature tries to regulate after surgery
  • itching and muscle aches caused by medications
  • malignant hyperthermia, causing high fever and muscle contractions after medications
  • headache due to spinal fluid leaking after spinal anesthesia
  • minor back pain where the needle was placed for spinal anesthesia
  • difficulty urinating (can occur after both general and spinal anesthesia)
  • nerve damage from the injection of the needle during spinal anesthesia
  • pneumothorax (collapsed lung) if the needle is placed incorrectly during spinal anesthesia[9]

Simultaneous bilateral THA requires longer anesthesia time throughout one procedure, while bilateral staged THA requires shorter anesthesia time throughout two procedures.

Blood loss:

A concern for increased blood loss with two surgical sites has been explored, and the results have been surprising. Zhou et al. found no significant difference in blood loss between unilateral THA, bilateral staged THA, or bilateral simultaneous THA.[6] In their literature review, Kirschbaum et al. found that simultaneous bilateral THA had a lower blood loss volume than staged bilateral THA.[7]

Blood Clots:

Blood clots after surgery are a significant cause of disability and medical costs. Medications and early mobility are the mainstays of preventing blood clots.

Ramezani et al. reviewed the literature and found no difference in blood clot rates between bilateral staged vs bilateral simultaneous THA. However, their research found a significantly lower rate of deep vein thrombosis in bilateral simultaneous THA when measured against bilateral staged THA. Conversely, they saw an increased rate of pulmonary embolism in bilateral simultaneous THA versus bilateral staged THA.[1]


For patients who meet selection criteria, bilateral simultaneous total hip arthroplasty may be an excellent option to reduce cost, hospital time, recovery time, and surgical risks. Having both hips operated on at the same time does make for a more intense recovery period, so anyone considering this procedure should discuss potential benefits and risks with their doctor.

Ramezani, A., Ghaseminejad Raeini, A., Sharafi, A., Sheikhvatan, M., Mortazavi, S. M., & Shafiei, S. H. (2022). Simultaneous versus staged bilateral total hip Arthroplasty: A systematic review and meta-analysis. Journal of Orthopaedic Surgery and Research, 17(1). https://doi.org/10.1186/s13018-022-03281-4
Sheth, N. P., & Foran, J. R. H. (2024, February). Total hip replacement - orthoinfo - AAOS. OrthoInfo. https://orthoinfo.aaos.org/en/treatment/total-hip-replacement/
American Society of Anesthesiologists. (2020, December 13). Statement on ​ASA physical status classification system. Standards and Practice Parameters. https://www.asahq.org/standards-and-practice-parameters/statement-on-asa-physical-status-classification-system
Partridge, T. C. J., Charity, J. A. F., Sandiford, N. A., Baker, P. N., Reed, M. R., & Jameson, S. S. (2020). Simultaneous or staged bilateral total hip arthroplasty? an analysis of complications in 14,460 patients using national data. The Journal of Arthroplasty, 35(1), 166–171. https://doi.org/10.1016/j.arth.2019.08.022
Kirschbaum, S., Hube, R., Perka, C., Ley, C., Rosaria, S., & Najfeld, M. (2023). Bilateral simultaneous hip arthroplasty shows comparable early outcome and complication rate as staged bilateral hip arthroplasty for patients scored ASA 1-3 if performed by a high-volume surgeon. International Orthopaedics, 47(10), 2571–2578. https://doi.org/10.1007/s00264-023-05871-1
Zhou, Z., Cai, G., Yuan, S., Song, L., Qian, P., Wang, X., Ning, X., Wang, J., & Jiang, W. (2023). Perioperative safety assessment of patients undergoing unilateral or bilateral hip replacements. Frontiers in Surgery, 10. https://doi.org/10.3389/fsurg.2023.944311
Yakkanti, R. R., Syros, A., Reddy, G. B., & D’Apuzzo, M. R. (2024). In-hospital complications and costs of simultaneous bilateral total hip arthroplasty: The case for selection and potential cost savings. Arthroplasty Today, 25. https://doi.org/10.1016/j.artd.2023.101294
Temporiti, F., Zanotti, G., Furone, R., Loppini, M., Molinari, S., Zago, M., Galli, M., Grappiolo, G., & Gatti, R. (2019). Functional and postural recovery after bilateral or unilateral total hip arthroplasty. Journal of Electromyography and Kinesiology, 48, 205–211. https://doi.org/10.1016/j.jelekin.2019.08.002
American Society of Anesthesiologists. (n.d.). Effects of anesthesia - brain and body: Made for this moment. Anesthesia, Pain Management & Surgery. https://www.asahq.org/madeforthismoment/anesthesia-101/effects-of-anesthesia/ 
Last edited on May 14th, 2024 5:53 pm