It is often observed that patients following total hip replacement have a hard time with rehabilitation, as patients commonly lose muscle mass and strength around the surgical site. The goal of this study is to learn if giving patients testosterone around their hip surgery can prevent them from losing muscle mass, as well as to see if it will improve their outcomes after surgery. The main question this study aims to answer is: Will perioperative testosterone administration increase lean mass in addition to improving functional and clinical patient reported outcomes greater than placebo?

Researchers will compare patients who were administered testosterone to standard of care (no administration of testosterone) to see if there is a difference in their recovery and outcomes.

Participants will be given either testosterone or saline for eight weeks beginning two weeks prior to surgery. Participants will have to answer questionnaires on how they are doing, as well as will do other testing during this time.

The purpose of this double blinded, randomized controlled trial is to determine if weekly intramuscular testosterone administration can prevent short-term catabolic loss of lean mass in patients undergoing total hip arthroplasty in addition to improving functional and patient-reported outcome scores. It is hypothesized that perioperative testosterone administration will increase lean mass in addition to improving functional and clinical patient reported outcomes greater than placebo. This is the first study, to our knowledge, investigating the effects of perioperative testosterone administration on male patients undergoing total hip arthroplasty.

Participants will be randomly assigned to receive testosterone or placebo treatment. This will be performed using a simple 1:1 randomization and will be provided to the study's designated team member who is not associated with the study, to be referred to as the pharmacist. Except for the statistician performing the randomization and the pharmacist, all individuals involved - including the investigators, study team, surgeon, physical therapist, and patient - will be blinded to the assigned treatment.

Informed consent documentation will include an in-depth discussion of the possible, but uncommon, risks of testosterone including allergic reactions, liver function test alterations, breast tenderness, hair growth or loss, polycythemia, and mood or mental changes. These potential adverse events will be monitored during all study visits.

The testosterone group will receive a 200mg dose of intramuscular testosterone cypionate (also known as Nandrolone) weekly for 8 weeks beginning 2 weeks prior to surgery. The 200 mg per week regimen is being selected with the goal of being a dose sufficient to provide an anabolic stimulus, and low enough to minimize potential adverse effects [10-13]. Control participants in the placebo group will follow the same schedule of injections with an intramuscular dose of saline instead of testosterone. All participants will follow a structured, standard of care, rehabilitation protocol within one week of surgery. All participants will follow a structured, standard of care, rehabilitation protocol within one week of surgery. Common markers of endocrine function will be monitored for potential systemic side effects of testosterone using blood analysis of pituitary hormones including luteinizing hormone (LH) and follicle stimulating hormone (FSH), prostate-specific antigen (PSA), alanine aminotransferase (ALT), hematocrit, hemoglobin, and white blood cell at 2 weeks preoperatively, the day of surgery, and then 2 weeks, 6 weeks, 3 months, and 2 years postoperatively.

Inclusion Criteria:

• Male patients over the age of 18 with a diagnosis of osteoarthritis or dysplasia that are undergoing total hip replacement will be recruited to the study and screened for eligibility. Inclusion criteria include clinical diagnosis of osteoarthritis or dysplasia, age 18 and older, and hypogonadism, defined as a testosterone level <300ng/dL or clinical signs of hypogonadism including reduced muscle mass and strength, decreased libido, erectile dysfunction, loss of body hair, low bone mineral density, infertility, gynecomastia, or incomplete or delayed sexual development.

Exclusion Criteria:

• Major exclusion criteria include previous arthroplasty of the affected hip, previous spine surgery, a past medical history significant for allergy to testosterone, prostate cancer, PSA >4 ng/ml, breast cancer, polycythemia, diabetes mellitus with a HbA1c > 7, BMI <18 or > 40, and preoperative motion or strength limitations that will affect postoperative rehabilitation.