Prehab Before Knee or Hip Replacement: Why the 6 Weeks Before Surgery Matter More Than You Think

The single best thing you can do before surgery

If you've been listed for a total knee replacement (TKR) or total hip replacement (THR), the surgical wait time can feel like dead air. It isn't. The 4–8 weeks before surgery are the highest-leverage window in your entire recovery — what happens in that period directly affects pain levels, mobility, length of hospital stay, and the speed of getting back to normal life after the operation. This is called prehabilitation, or 'prehab', and the evidence for it is strong and growing.

Why prehab works

Going into joint replacement surgery, most patients have lost 20–40% of strength in the affected leg compared to the other side, because of months or years of pain-driven offloading. After the surgery, the leg gets weaker still in the first 4–6 weeks due to the trauma of the operation itself. If you start the recovery already deconditioned, you're climbing out of a deeper hole. If you start it stronger and fitter, the hole is shallower and the climb is faster.

The mechanisms are mechanical and physiological:

• Higher pre-surgical strength means less catastrophic loss after surgery.
• Better cardiovascular fitness reduces surgical complications, particularly DVT and pulmonary issues.
• Better range of motion at the joint going in often translates to better range coming out.
• Practised use of crutches or walking aids before the day of surgery means less anxiety and better technique afterwards.
• Established physio relationship means the post-operative care starts on day one of recovery, not the first follow-up four weeks in.

What the evidence says

Multiple systematic reviews have looked at prehab for knee and hip replacement:

• Wang et al. 2016 meta-analysis showed prehab reduces postoperative pain and improves function up to 12 weeks post-TKR.
• Wallis & Taylor 2011 found reduced length of hospital stay following prehab, particularly for THR.
• Cochrane reviews note moderate-quality evidence for improvements in pre-operative function and shorter post-op recovery.

The signal is clear: prehab helps, especially in patients with significant pre-surgical deconditioning.

The prehab plan — knee replacement

Six weeks, three sessions per week, ~30 minutes each. Adjust for pain and individual capacity.

• Quadriceps strengthening: sit-to-stands, mini-squats in pain-free range, terminal knee extensions, leg press (in clinic). Quad strength is the single biggest predictor of post-TKR function.
• Hamstring and glute strengthening: bridges, single-leg bridges, hamstring curls, hip thrusts.
• Calf raises: for circulation and post-op DVT prevention.
• Range of motion work: heel slides, prone knee bends, gentle stretches.
• Cardiovascular work: stationary bike (excellent — minimal joint load, builds quads and aerobic base), pool walking, recumbent bike, arm ergometer if leg work is too painful.
• Crutch and walking-frame practice: get comfortable with the aid you'll use post-op.

The prehab plan — hip replacement

Same structure, hip-focused targets:

• Gluteal strength: bridges, side-lying clams, single-leg bridges, hip thrusts.
• Hip abductor work: side-lying leg raises, banded sidesteps, monster walks.
• Quadriceps and hamstring strengthening: sit-to-stands, leg press, hamstring bridges.
• Trunk and core control: dead bugs, bird dogs, modified planks.
• Cardiovascular work: as above.
• Hip precautions practice: getting in and out of bed, putting on socks with a sock aid, in/out of car — whichever approach (posterior or anterior) the surgeon is using.
• Home setup: raised toilet seat, shower chair if needed, removing trip hazards.

The 'real life' practice your physio should include

Beyond strength, the post-op weeks will involve very specific tasks. Practising them in prehab reduces anxiety and improves performance:

• Getting in and out of bed using log-roll or sliding technique.
• Sitting down and standing up from chairs of different heights.
• Negotiating stairs with crutches — up with the good leg first, down with the bad leg first.
• Getting in and out of the car (low cars need particular technique).
• Showering safely.
• Dressing — sock aids, long-handled shoehorns, reachers.

Hydrotherapy — underused gem

For patients in significant pain who can't tolerate full land-based loading, hydrotherapy is excellent prehab. Buoyancy offloads the joint, water resistance builds strength, walking patterns improve, and cardiovascular conditioning happens. Most public hospitals in Southwest Sydney have hydrotherapy programs, and several private pools host physio-led classes.

Don't skip the head game

Joint replacement is a big procedure. Pre-surgical anxiety affects post-surgical pain and recovery. Prehab time is also for:

• Education on the procedure — what to expect day-by-day in the first week.
• Realistic timelines for return to walking, driving, work, sport.
• Pain management plans, including expectations of medication tapering.
• Reducing fear-avoidance — patients who go in expecting a slow, painful recovery have a slower, more painful recovery.

What about pain during prehab?

We work in pain-tolerable ranges, not pain-free. 0–4/10 pain during exercise that settles within 24 hours is normal and acceptable. Severe pain or pain that escalates is a signal to modify. Most prehab exercises don't load the worst-affected positions of the joint — quad work avoids deep flexion in TKR patients; hip work avoids end-range positions in THR patients.

If you've already had surgery

Most of these principles transfer directly into the post-op rehab phase. See our post-surgery rehab guide for the full 12-week framework. For knee-specific content, see our knee pain piece. The principles are the same: progressive loading, real-life function, structured progression.

The biggest mistake people make

Waiting for the surgical date 'because the joint is going to be replaced anyway.' The new joint is mechanical; the muscles around it are still yours. The hardware doesn't recover from the surgery, you do — and you do it faster the stronger you go in.

Book a prehab assessment

If you've been listed for a knee or hip replacement at Liverpool, Fairfield, Bankstown, or Royal Prince Alfred — or any of the Southwest Sydney surgical centres — give yourself the best possible recovery. Book a prehab assessment at Evolve Physio & Mastery, Cabramatta. We'll design a 4–8 week program, coordinate with your surgical team if helpful, and be ready to pick up your post-op rehab the day you're cleared.

References: Wang L et al. 2016 'Preoperative exercise programs for patients undergoing total knee arthroplasty: a systematic review and meta-analysis' (Phys Ther); Wallis & Taylor 2011 'Pre-operative interventions for hip or knee replacement' (Osteoarthritis Cartilage); Moyer et al. 2017 prehabilitation in total joint arthroplasty Cochrane review.