Prehab and Rehab: Why Physical Therapy Starts Before Surgery, Not After

Your knee replacement is on the calendar. Six weeks out. You have the pre-op checklist, a list of medications to stop, and a ride arranged for the morning of. What you may not have is a plan for the six weeks in between. Prehab before knee replacement is that plan, and it matters more than most people expect.

October is National Physical Therapy Month, so this is a good time to say what our physical therapists tell nearly every joint replacement patient: recovery does not start the day after surgery. It starts now. Below you will find what “prehab” is, what the research says it does and does not do, what the first weeks after surgery look like, and how to get started at one of our eight Central Maryland physical therapy locations.

Reviewed by: Russ Patti, DPT, MTC, CMTPT, a physical therapist and director of physical therapy at OACM. He holds a doctorate in physical therapy from the University of St. Augustine for Health Sciences and certifications in manual therapy and trigger point dry needling.

Watch: Physical Therapy: Prehab and Rehab for Total Knee Replacement, Russ Patti, DPT

What prehab before knee replacement is

Prehab is short for prehabilitation. It is a course of exercise and education in the weeks before surgery, usually guided by a physical therapist, aimed at building strength and range of motion in the joint that is about to be replaced and in the muscles around it.

The logic is simple. A knee that goes into surgery with a stronger quadriceps and a fuller range of motion has less ground to make up afterward. And a patient who already knows the post-op exercises does not have to learn them for the first time while sore, tired, and on pain medication.

AAOS makes the same point in its guidance on preparing for joint replacement: “If you become familiar with the exercises now, you will be ready to perform them after surgery.” It also notes that for hip and knee replacement, strengthening your upper body makes a walker or crutches easier to manage in the first days home.

At OACM, pre-surgery rehabilitation starts with an assessment of your strength, range of motion, and how you move, followed by a targeted exercise plan and education: how to use a walker or crutches, how to move safely, and which exercises you will begin right after surgery. For a knee or hip replacement, the strengthening work leans on the quadriceps, hamstrings, and gluteal muscles. Our therapists’ guidance on prehab puts the ideal window at six to eight weeks before surgery, though even a shorter runway is worth using.

What the research says about prehab before knee replacement, and what it does not

This is where we want to be careful, because prehab gets oversold online.

A 2025 meta-analysis of randomized trials in Frontiers in Medicine found that prehab before knee replacement reduced post-operative pain at one, three, and six months, and modestly improved knee extension at one month and flexion at three months. An earlier 2021 review found similar gains in flexion and quadriceps strength.

What the 2025 analysis did not find was any meaningful change in hospital stay. So if someone tells you prehab will get you home a day sooner, be skeptical. What the evidence supports is more modest and more useful: less pain in the months after surgery and an earlier return of motion. Many patients experience exactly that. Not every patient does.

What the first weeks after surgery look like

Rehab picks up where prehab leaves off, and it starts sooner than people expect.

According to AAOS, most patients begin exercising the knee within hours of surgery, with a physical therapist teaching the first exercises before you leave the hospital. The stay is usually a day or two. From there, the AAOS guidance on activities after knee replacement lays out the broad timeline: most daily activities within about three to six weeks, driving at four to six weeks, prescribed exercises for at least two months, and swelling that can linger three to six months.

Inside that timeline, outpatient physical therapy is where the work happens. OACM’s post-surgery rehabilitation follows a set sequence: an initial evaluation against your surgeon’s report, early work on pain and swelling, progressive strengthening as you heal, functional exercises that mimic daily tasks, and hands-on manual therapy for mobility. The visit schedule follows your surgeon’s protocol, with a home program in between. The AAOS exercise guide suggests 20 to 30 minutes of exercise daily plus regular walking, and that is roughly what your therapist will ask of you.

Watch: Post-Op Rehab: What Your Surgeon Didn’t Tell You

What a physical therapist actually does at a visit

Patients sometimes picture physical therapy as supervised stretching. It is closer to detective work with a plan attached.

Since 2016, every physical therapist graduating in the United States has earned a Doctor of Physical Therapy degree and passed a national licensing exam. Your first visit is an evaluation: how far the joint bends and straightens, how strong the surrounding muscles are, how you walk, what brings the pain on. The plan is built from those measurements and changes as the numbers change.

Physical therapist assistants work alongside them. PTAs are licensed clinicians who carry out the plan under a physical therapist’s direction, so on some visits a PTA may guide your exercises. The OACM therapy team also includes occupational therapists for hand, wrist, and elbow rehabilitation.

Watch: What Does a Physical Therapist Really Do?

About Russ Patti, DPT, MTC, CMTPT

Russ Patti is a director of physical therapy at OACM. His profile notes that during his doctoral training he “completed various rotations in specialized spine clinics and general orthopedic settings,” and that after school he “earned his Manual Therapy Certification (MTC) and was also trained and certified in Trigger Point Dry Needling through Myopain Seminars.” He played collegiate baseball at York College of Pennsylvania and has a particular interest in sports rehabilitation, “particularly with high school athletes because of their passion.”

Listen: Empowering New Grads: The OACM Therapy Team Experience, Russ Patti, DPT, and Matthew Masangcay, DPT, on A Bone to Fix.

Schedule prehab before knee replacement at one of our eight locations

If you have a joint replacement scheduled this fall, or you are still deciding, you can start physical therapy at OACM without waiting for the surgery date. We have therapists in Catonsville, Clarksville, Columbia, Eldersburg, Ellicott City, Fulton, Laurel, and Westminster.

Call our physical therapy line at (443) 478-4449, or schedule online with the surgeon’s office and ask about prehab at the same time.

Frequently asked questions

Disclaimer

The information in this article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always speak with a qualified orthopedic provider about your specific symptoms and medical history. To schedule an appointment with Orthopaedic Associates of Central Maryland, call (410) 644-1880 or visit mdbonedocs.com.