Why Pre-Hab Matters
Total knee replacement (TKR) is one of the most common orthopedic surgeries performed in the United States, with over 700,000 procedures annually. The surgery itself is highly successful — but the recovery is entirely dependent on the strength and mobility you bring into the operating room. Patients who arrive stronger, with better range of motion and better neuromuscular control, consistently recover faster, leave the hospital sooner, and return to independent function earlier than those who do not prepare.
The reason is straightforward: after surgery, your quad — the primary muscle that controls the knee — will be significantly inhibited by pain and swelling. The stronger your quad is before surgery, the more function you retain even with that inhibition. Physical therapists call this "pre-habilitation," and the research supporting it is clear.
The SLR Protocol — The Most Important Exercise
The Straight Leg Raise (SLR) is the cornerstone of TKR pre-hab. It is the exercise that orthopedic surgeons and physical therapists most consistently recommend because it builds quad strength without bending the knee — which means it can be performed even when the joint is severely arthritic and painful. The goal is 50 repetitions per day, every day, for the 6–8 weeks before your surgery date.
Straight Leg Raise — 50 Reps Per Day
Lie on your back on a firm surface. Bend the unaffected knee to 90 degrees with the foot flat on the floor. Tighten the quad of the surgical leg by pressing the back of the knee toward the floor — this is called a quad set. Keeping the quad tight and the leg straight, raise the leg to the height of the bent knee (approximately 45 degrees). Hold for 1 second, then lower slowly over 2–3 seconds. That is one rep. Complete 50 reps per day, broken into sets of 10–15 as needed.
The slow lowering (eccentric phase) is where the strength gains occur. Do not drop the leg — control the descent every single rep.
The Wrecked Gorilla exercise portal includes a dedicated SLR tracker that logs your daily rep count, shows your progress toward the 50-rep goal, and tracks your streak. Patients who track their reps are significantly more consistent than those who do not. The portal is included free with the Knee Pre-Hab Guide.
The Full Pre-Hab Exercise Program
In addition to the SLR, a complete pre-hab program includes exercises that address range of motion, quad strength through range, and hip strength. The following exercises complement the SLR and should be performed 3–4 times per week (the SLR is done daily).
Heel Slides
Lie on your back with both legs straight. Slowly slide the heel of the surgical leg toward your buttocks, bending the knee as far as comfortable without pain above a 4/10. Slide back to straight. This exercise maintains and improves knee flexion range of motion before surgery. Patients who arrive at surgery with better flexion consistently achieve better flexion post-operatively. The goal is to reach 90 degrees of knee bend before your surgery date.
Short Arc Quad
Lie on your back. Place a rolled towel or pillow under the surgical knee to prop it up at approximately 40 degrees of bend. From this position, straighten the knee fully by tightening the quad, hold for 2 seconds, then lower slowly. This exercise builds quad strength through the terminal range of extension — the last 40 degrees of straightening — which is the range most affected by TKR and the range most critical for walking normally.
Seated Knee Extension (Terminal)
Sit in a chair. Straighten the surgical leg fully, squeezing the quad hard at the top. Hold for 3 seconds, then lower slowly. This is the seated version of the short arc quad and can be done anywhere — at a desk, watching television, or in a waiting room. Frequency matters more than intensity for this exercise: aim for 3 sets of 15 at least twice per day.
Standing Hip Abduction
Stand holding a counter or wall for balance. Keeping the surgical leg straight and the pelvis level, lift it out to the side approximately 12–18 inches. Lower slowly. This exercise strengthens the hip abductors, which are critical for walking stability after TKR. Patients with weak hip abductors often develop a Trendelenburg gait (hip drop) after surgery, which places excessive stress on the new knee. Address this before surgery, not after.
Preparing Your Home
Physical preparation is only half of pre-hab. The other half is preparing your home environment so that you can navigate it safely and independently when you return from the hospital. Most TKR patients are discharged within 1–2 days of surgery and must be able to manage stairs, get in and out of bed, and use a walker or cane safely. The following checklist covers the most critical home modifications.
Home Readiness Checklist
Clear all trip hazards — loose rugs, electrical cords, and clutter on the floor. You will be using a walker and your balance will be compromised.
Set up a recovery station on the main floor if possible — a recliner or firm chair with armrests, a side table for medications and water, and a phone charger within reach.
Install grab bars in the shower and near the toilet, or arrange for a shower chair and raised toilet seat. These are available at most pharmacies and are essential for safe independent hygiene.
Prepare 1–2 weeks of easy meals in advance, or arrange for meal delivery. You will not be able to stand at a stove comfortably for the first 1–2 weeks.
Arrange for someone to drive you to your post-operative appointments for the first 4–6 weeks. You will not be cleared to drive until your surgeon confirms adequate quad strength and reaction time.
The 6-Week Pre-Hab Timeline
Weeks 1–2: Begin the SLR protocol at 25 reps per day and build to 50 reps by the end of Week 2. Add heel slides and seated knee extensions daily. Focus on establishing the habit and tracking your consistency.
Weeks 3–4: Maintain 50 SLR reps daily. Add short arc quads and standing hip abduction 3 times per week. Begin home preparation — order equipment, clear hazards, set up the recovery station.
Weeks 5–6: Maintain the full program. Your quad should feel noticeably stronger. Focus on achieving 90 degrees of knee flexion with heel slides. Complete all home preparation. Confirm post-operative arrangements (transportation, meals, caregiver support).
Get the Knee Pre-Hab Guide
The complete DPT-written pre-operative program for total knee replacement. Includes the 50-rep/day SLR protocol, 6 illustrated exercises, a weekly schedule, and free access to the exercise tracking portal with a built-in SLR goal tracker.
Get It for $19.99 →Instant PDF download · SLR tracker portal included · No clinic, no waitlist
Educational Disclaimer: This article is for educational and informational purposes only. It does not establish a provider-patient relationship and is not a substitute for professional medical advice, diagnosis, or treatment. Always follow the specific instructions provided by your orthopedic surgeon and physical therapist. Consult your surgeon before beginning any pre-operative exercise program.