Short answer: Knee replacement is a surgery where the damaged joint surfaces of the femur and tibia are replaced with an implant made of metal and polyethylene. It's called total knee arthroplasty. It is indicated when chronic knee pain, usually caused by knee osteoarthritis, no longer responds to conservative treatment (medication, physical therapy, injections) and begins to significantly affect quality of life. The surgery takes 60–90 minutes, hospitalization is 3–5 days, and full recovery takes between 6 and 12 months.
What Exactly is a Knee Replacement?
The knee joint is formed by the lower end of the femur, the upper end of the tibia, and the patella (kneecap), connected by ligaments and covered with cartilage. Cartilage is the smooth tissue that allows bones to glide over each other without pain. When this cartilage wears down—a process called knee osteoarthritis—the bones rub directly against each other, and every step becomes painful.
A knee replacement doesn't 'heal' the joint. It replaces the faulty mechanism with an artificial one. Imagine an old, rusty hinge that creaks with every opening. You replace it with a new hinge. That's essentially what we do with the knee, but on a much more precise scale.
The implant has three components:
- A femoral component made of a metal alloy (usually cobalt-chrome), which covers the lower end of the femur;
- A tibial component made of titanium or a similar alloy, anchored to the upper part of the tibia;
- An insert made of very high molecular weight polyethylene, which acts as artificial cartilage between the two metal components.
In some cases, we also replace the back surface of the patella with a polyethylene component.
Types of Prostheses
There are two main types, chosen based on your situation:
Total Knee Arthroplasty (TKA): Replaces all three joint surfaces. It is the most common—over 90% of cases. Recommended for advanced osteoarthritis in all three compartments of the joint.
Unicompartmental Knee Arthroplasty (Partial Knee Replacement): Replaces only a part of the joint when only one compartment is affected. Advantage: smaller incision, faster recovery, better mobility. Disadvantage: if the wear extends to other compartments, a total replacement may be needed later.
The decision between the two is made based on X-rays and a clinical exam. During the consultation, I will explain specifically what would be indicated in your case.
When is a Knee Replacement Truly Necessary?
This is where things get important, and it's time to be completely honest with each other.
Knee replacement is a serious operation. It permanently alters your anatomy, has real risks, and recovery requires discipline. It is by no means a 'simple fix.' That's why, before sending you to the operating table, I carefully evaluate if you are truly at the right moment.
Clear Indications for a Knee Replacement:
- Chronic knee pain (for months or years) that no longer responds to anti-inflammatory drugs;
- Significant functional limitation — you can no longer climb stairs, sleep due to pain, or walk more than 200–300 meters without stopping;
- X-ray showing advanced wear — stage III or IV knee osteoarthritis (Kellgren-Lawrence classification), with cartilage loss and bone-on-bone friction;
- Insufficient response to conservative treatment for at least 6 months: targeted physical therapy, hyaluronic acid or PRP injections, lifestyle modifications;
- Affected quality of life — not just physical pain, but also loss of independence, social isolation, and reactive depression.
When I'll Tell You It's Not Time Yet:
- You are under 50 with moderate osteoarthritis—we first try the entire conservative arsenal;
- You respond well to injections (PRP, hyaluronic acid)—we continue on this path;
- We can still discuss the biological options for postponing a replacement, when the stage of the osteoarthritis allows it;
- You have severe obesity (BMI > 40)—the surgery is risky and the implant wears out prematurely; we first optimize weight, if possible;
- You have active infections or uncontrolled diabetes—the risk of post-operative infection is too high;
- The loss of function is moderate and you tolerate the pain with occasional medication—the surgery can wait.
When I'll Tell You It Might Be Too Late to Postpone:
- You start developing fixed deformities (pronounced varus or valgus knee);
- Muscle contractures appear;
- The other joint begins to be overloaded as compensation;
- Quality of life is profoundly affected and visibly deteriorates month by month.
Osteoarthritis doesn't only come with age: sometimes it is post-traumatic osteoarthritis after a tibial plateau fracture, and then the replacement discussion comes earlier, at a younger age.
Before you decide, it may help to read the 35 questions patients ask me most often, answered one by one.
The decision to operate is a conversation, not a decree. During the consultation, I lay all the cards on the table: what your X-ray shows, what the clinical exam says, what non-surgical alternatives are still reasonable, and what the real risks of the surgery are for you specifically. Then, you decide.
How the Surgery is Performed—Step by Step
Many patient fears come from the unknown. Here's exactly what happens:
The evening before: Hospital admission. Fasting from the previous evening. A mild sedative for sleep if you need it. A visit from the anesthesiologist who will explain the type of anesthesia.
The morning of the surgery: Preparation—shower with antiseptic soap, changing into a special gown, IV line insertion. A brief chat with me—I'll answer any questions you have at that moment.
In the operating room:
- Anesthesia (usually spinal, rarely general)—takes 10–15 minutes to take effect;
- Positioning on your back, with the knee flexed;
- Disinfection and sterile draping;
- Longitudinal incision on the front of the knee (10–15 cm);
- Exposure of the joint, final assessment of the damage;
- Precise cuts of the femoral and tibial ends using special guides;
- Placement of the implant components (femoral + tibial + insert);
- Checking for stability, mobility, and alignment;
- Abundant washing with saline and antiseptic solution;
- Suturing in anatomical layers.
Total duration: 60–90 minutes for standard cases. Longer for complex cases (large deformities, previous surgeries).
Immediately after surgery: You will spend 1–2 hours in the recovery room, under monitoring. Then you will return to your ward room. Pain is controlled with intravenous and then oral analgesics.
On the first post-operative day (very important): you get out of bed, take your first steps with a walker, under the supervision of a physical therapist. This isn't 'rushing'—it's an integral part of the surgery's success. Prolonged immobilization increases the risk of thrombosis and joint stiffness.
Recovery—The Weeks That Matter
Recovery after a knee replacement is a marathon, not a sprint. Patients who understand this from the beginning have the best results.
Week 1: you are still hospitalized (3–5 days) or at home with daily physical therapy; walking with a walker around the bed and in the hallways; passive and active assisted mobility exercises; anticoagulant treatment to prevent thrombosis; daily dressing changes, stitches removed at 14 days.
Weeks 2–4: continue walking with a walker, possibly crutches for short periods; physical therapy 3–5 times a week; knee mobility should reach 90° flexion by the end of week 4; we begin light muscle training; return to sedentary work (office job) at 2–4 weeks.
Weeks 5–8: transition to a cane; target mobility: 120° flexion; walking without support for short distances; resuming driving (at 6–8 weeks); the first 'I don't feel my knee anymore' moments appear—an excellent sign.
Months 3–6: complete independence in walking; light recreational activities: long walks, swimming, stationary bike; continued physical therapy 1–2 times/week for maintenance; muscle strength still rehabilitating.
Month 6 to 1 year: maximum recovery—most patients report a significant reduction in pain; final mobility: 120–135° flexion (a natural knee has 140°); resumption of low-impact sports (golf, hiking, swimming, cycling); permanently not recommended activities: running on pavement, repetitive jumping, impact sports (competitive soccer, basketball).
Risks—Honestly, Without Hiding Them
Every surgery has risks. Hiding this doesn't help you. Here are the real risks, with real incidences:
| Risk | Approximate Incidence | How We Prevent It |
|---|---|---|
| Post-operative infection | 1–2% (in a cohort of 79,367 primary replacements: 2.0%)⁷ | Prophylactic antibiotics, strict asepsis, controlled environment |
| Deep vein thrombosis (DVT) | about 1.2% at 30 days, with prophylaxis⁸; 30%+ without | Anticoagulant for 4–6 weeks post-op, early mobilization |
| Pulmonary embolism | under 1% | Same measures as for DVT |
| Reduced mobility (less than 90° flexion) | 5–10% | Aggressive physical therapy, manipulation under anesthesia if necessary |
| Residual pain | 12–15% long-term, up to 2 years (usually tolerable)⁶ | Correct patient selection, precise technique; pain present at three months is frequent and does not mean the surgery has failed |
| Prosthesis wear/loosening | under 1%/year, cumulative | Correct technique, normal weight, avoiding impact sports |
| Need for revision surgery | ~5% at 10 years, ~15% at 20 years² | Quality implant, long-term follow-up |
| Vascular/nerve damage | under 0.5% | Careful technique, pre-operative planning |
Post-operative infection
Incidence: 1–2% (in a cohort of 79,367 primary replacements: 2.0%)⁷
Prophylactic antibiotics, strict asepsis, controlled environment
Deep vein thrombosis (DVT)
Incidence: about 1.2% at 30 days, with prophylaxis⁸; 30%+ without
Anticoagulant for 4–6 weeks post-op, early mobilization
Pulmonary embolism
Incidence: under 1%
Same measures as for DVT
Reduced mobility (less than 90° flexion)
Incidence: 5–10%
Aggressive physical therapy, manipulation under anesthesia if necessary
Residual pain
Incidence: 12–15% long-term, up to 2 years (usually tolerable)⁶
Correct patient selection, precise technique; pain present at three months is frequent and does not mean the surgery has failed
Prosthesis wear/loosening
Incidence: under 1%/year, cumulative
Correct technique, normal weight, avoiding impact sports
Need for revision surgery
Incidence: ~5% at 10 years, ~15% at 20 years²
Quality implant, long-term follow-up
Vascular/nerve damage
Incidence: under 0.5%
Careful technique, pre-operative planning
These numbers are not meant to scare you. They are meant to show you that the risks are small, but real. Most patients are satisfied after the surgery, but about one in five is not—in the cited study, satisfaction was between 72% and 86% for pain and between 70% and 84% for function (Bourne RB et al., Clin Orthop Relat Res 2010). The strongest predictor of dissatisfaction was not age or implant type, but the unmet expectation—which is why a realistic discussion before surgery matters.
How the cost is covered
How a procedure is covered differs from case to case — depending on your situation and on the type of procedure. There is no generally valid answer, and this is precisely why you will not find figures or promises on this site. At the consultation, once I have seen your case, I will tell you exactly which options exist for you.
Have a question? Write to me — it is a first point of contact.
If surgery has already been proposed to you and you want to hear one more view before you decide, you can write to me — an orthopedic second opinion is a natural first step, not an affront.
Frequently Asked Questions
About Me
I am Dr. Alexandru Florian Grecu, a senior consultant orthopedic and trauma surgeon with clinical practice in Craiova. I consult and operate in Craiova. Depending on each patient's situation, some procedures may be covered by health insurance — the options are discussed at the consultation.
My main specializations are hip and knee arthroplasty, knee arthroscopy, and regenerative therapy with PRP and hyaluronic acid. Besides my clinical work, I teach orthopedics at the University of Medicine and Pharmacy of Craiova, as a Senior Lecturer.
Orthopedics is a specialty where what matters is not just the day of the surgery, but also what happens 5, 10, or 20 years later. I choose the implants, the technique, and the timing of the intervention with this long-term perspective in mind. My patients are primarily people who want to regain their lost mobility—whether for work or to watch their grandchildren grow up.
For complete details about my professional background, see the About page.