Recombinant Human Growth Hormone (rHGH) for Knee Osteoarthritis (KORR)

• Somatropin (recombinant human growth hormone) (Drug): Study participants will deliver Somatropin via self-administered subcutaneous injection into the abdomen or gluteal region once per day for six weeks at a dose of 0.5mg/day per body surface area (0.5mg/m2/day).
• bacteriostatic saline placebo (Drug): Study participants will deliver bacteriostatic saline via self-administered subcutaneous injection into the abdomen or gluteal region once per day for six weeks in an identical delivery device to the experimental arm.

Primary outcomes

• Feasibility of the medication administration [6 weeks after treatment begins.]: Participant adheres to self-administration of injections once daily for 6 weeks.

Secondary outcomes

• Clinical Outcomes: knee extension strength [At 6 weeks and 24 months time points after enrolment]: Participants' knee extension strength will be measured using HUMAC Norm Extremity Strength Testing system.
• Clinical Outcome: knee flexion strength [At 24 months after enrolment.]: Participants' knee flexion strength will be measured using HUMAC Norm Extremity Strength Testing system.
• Clinical Outcomes: thigh muscle strength [At baseline, 6 weeks, 3 months, 6 months, 12 months, and 24 months study visits.]: Participants' thigh muscle strength will be measured through hip flexion, hip abduction and knee flexion using a goniometer.
• Clinical Outcomes: Kinematic Gait Analysis [At baseline, 6 weeks and 6 months study visits.]: Participants' kinematic gait analysis will be measured with single/ two leg hop/jump and single/ two leg squat, using the Theia Markerless system before and after treatment.
• Thigh circumference [At baseline, 6 weeks, 3, 6, 12 and 24 months study visits]: Participant's measurements of function will be measured by their thigh circumference compared to the contralateral leg, and baseline.
• Mid-calf circumference [At baseline, 6 weeks, 3, 6, 12 and 24 months study visits]: Participant's measurements of function will be measured by their mid-calf circumference compared to the contralateral leg, and baseline.
• Abdominal circumference [At baseline, 6 weeks, 3, 6, 12 and 24 months study visits]: Participant's measurements of function will be measured by their abdominal circumference.
• Range of motion of both knees [At baseline, 6 weeks, 3, 6, 12 and 24 months study visits]: Participant's measurements of function will be measured by Range of motion of both knees.
• 6 Minute Walk Test (6MWT) [At baseline, 6 weeks, 3 months, 6 months, and 12 months after enrolment.]: Participants' distance traveled in the span of 6 minutes will be measured on a treadmill (unit: total meters).
• Activity Count [From enrolment to the 12-week study visit.]: Participants' activity count will be measured using a fitness tracker (ActiGraph) worn around the ankle. The total time the fitness tracker is worn will be monitored by the device.
• Knee Injury and Osteoarthritis Score (KOOS) [At baseline, 6 weeks, 3, 6, 12 and 24 months study visits]: Participants will be asked to complete the Knee Injury and Osteoarthritis Score (KOOS) questionnaire to measure their overall well-being. KOOS uses a Likert scale ranging from 0 (No problems) to 4 (Extreme problems).
• 20-Item Short Form Survey (SF-20) [At baseline, 6 weeks, 3, 6, 12 and 24 months study visits]: Participants will be asked to complete the 20-Item Short Form Survey Instrument (SF-20) questionnaire which measures their overall well-being including their physical and social functioning.
• Tegner Activity Scale [At baseline, 6 weeks, 3, 6, 12 and 24 months study visits]: Participants will be asked to complete the Tegner Activity Scale questionnaire, which measures their level of activity. A 11-point scale (ranging from 0 - 10) is used where a higher score indicates higher level of activity.

Sex: All, ages: 18 Years to 65 Years

Inclusion Criteria:

* Between 18 - 65 years old.
* Diagnosis of isolated knee osteoarthritis for greater than 6 months.

Exclusion Criteria:

* Previous or pending major intra-articular or reconstructive surgery to the involved knee, including femoral/tibial osteotomies, ligament repair/reconstruction, or cartilage transplantation. Patients with remote (>1 year) diagnostic arthroscopy, arthroscopic debridement, meniscectomy, or meniscal repair may be allowed to participate at the investigators' discretion.
* Previous major trauma (including fracture, dislocation, open injury) to the involved knee, or ipsilateral hip, knee, ankle, or hip. Patients with prior complete ligament tears will be excluded, patients with chronic partial thickness ligament tears or degenerative/complex meniscal tears (>6 months from injury) may be included at the investigators' discretion
* Recent (less than 6 months) intra-articular injection into the involved knee.
* High grade ligamentous knee injury.
* Known allergy to recombinant human growth hormone (rHGH) or reconstitutive solutions.
* BMI of less than 20 or greater than 35.
* Documented history of growth disorder of bones or connective tissue, type 1 or 2 diabetes, myopathy, cancer, endocrine disorder, severe hypertension (SBP > 180) or rheumatologic disorder.
* Pregnant or breastfeeding, or actively attempting to get pregnant.
* Currently on hypoglycemic therapy, oral estrogen or glucocorticoid replacement therapy.
* Would have difficulty with the self-injection schedule or other cognitive/ functional limitations.
* Have taken creatine within 7 days before baseline. Potential participants will be given the option to pause their supplements and then re-screen if they are interested in the study,
* Have taken anabolic steroids within 42 days (6 weeks) before baseline. Potential participants will be given the option to pause their supplements and then rescreen if they are interested in the study,
* Vital signs or routine bloodwork outside of normal range.

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• Dr. David Wasserstein, Principal investigator, Sunnybrook Health Sciences Centre