Total Knee Replacement

Why this approach — at MOS

Fellowship training in adult reconstruction provides a foundation in implant selection, alignment technique, and complication management that is the baseline for performing total knee replacement well. The procedure has become reproducible in trained hands, but the details still matter — particularly alignment and soft tissue balancing.

We use a measured resection or gap balancing technique depending on the case, and pay close attention to the posterior slope of the tibial cut, which influences both stability and range of motion. Implant selection is based on bone quality, deformity pattern, and expected activity demands; we are not a single-implant practice. Modern cemented implants from established manufacturers with long registry track records form the core of our reconstruction inventory.

Robotic-assisted surgery is available and used selectively where it provides meaningful precision gains, particularly in knees with unusual anatomy or significant deformity. It is not universally applied because a skilled surgeon using conventional instrumentation achieves excellent results, and the evidence that robotics improves patient-reported outcomes compared to conventional technique remains mixed at medium-term follow-up.

Post-operatively, we use a multimodal pain management protocol that significantly reduces opioid requirements — nerve blocks, oral anti-inflammatories, acetaminophen, and a cryotherapy system combine to provide effective pain control. Our goal is to mobilize patients safely on the day of surgery and discharge them as soon as medically appropriate. Patients across Montgomery County benefit from our in-house physical therapy program, which continues rehabilitation after discharge.

Who is a candidate?

Indications

• End-stage knee osteoarthritis with bone-on-bone contact confirmed on weight-bearing X-rays, causing daily pain that significantly limits function
• Inflammatory arthritis (rheumatoid, psoriatic) involving multiple compartments of the knee unresponsive to medical management
• Post-traumatic arthritis from prior fracture, ligament injury, or meniscectomy causing severe joint narrowing
• Avascular necrosis of the femoral condyle or tibial plateau with extensive involvement
• Failed prior partial knee replacement with progressive disease in other compartments
• Significant angular deformity (varus or valgus) combined with symptomatic arthritis

Contraindications

• Active knee joint infection or recent remote infection that has not cleared
• Extensor mechanism deficiency (inability to extend the knee) without a plan to address it
• Vascular insufficiency affecting the operative limb
• Morbid obesity (BMI >40) — elevated complication risk; weight loss is strongly encouraged before surgery
• Neurological conditions causing significant muscle weakness around the knee
• Arthritis limited to one compartment — partial knee replacement may be more appropriate

Conservative Treatment First

Total knee replacement is reserved for patients who have genuinely exhausted non-surgical options. The standard course of conservative management for knee arthritis includes: weight loss (every pound lost removes approximately 4 pounds of force from the knee joint), supervised physical therapy focused on quadriceps and hip strengthening to stabilize the joint and reduce pain, NSAIDs and topical anti-inflammatories, corticosteroid injections for acute flares, and occasionally hyaluronic acid (viscosupplementation) injections. Assistive devices — a cane or walker — and activity modification (avoiding high-impact activities that provoke symptoms) round out the conservative program.

The timing of total knee replacement is an individual decision that weighs the severity of functional limitation, the patient's overall health and surgical risk, and the patient's own assessment of how much the pain affects their daily life. Surgery is not indicated based on X-ray findings alone — severe arthritis on imaging with minimal functional limitation does not justify replacement. Conversely, severe functional limitation with X-ray confirmation of end-stage disease is the appropriate indication, regardless of the patient's age.

The procedure

What Is Total Knee Replacement?

Total knee replacement (also called total knee arthroplasty) is a surgical procedure that removes the damaged cartilage and bone surfaces of the knee joint and replaces them with metal and plastic implant components. It is performed at a hospital under general or spinal anesthesia and takes 60 to 90 minutes. It is the most reliably effective treatment for end-stage knee arthritis.

The knee joint is formed by the meeting of three bones: the femur (thighbone), the tibia (shinbone), and the patella (kneecap). A layer of smooth articular cartilage covers each contact surface, allowing the joint to move with minimal friction. When arthritis damages or destroys this cartilage — through wear, inflammatory disease, or post-traumatic changes — the resulting bone-on-bone contact causes pain, stiffness, deformity, and loss of function that cannot be restored by non-surgical means.

During total knee replacement, the surgeon removes a precise, measured layer of damaged bone and cartilage from the ends of the femur and tibia and from the underside of the patella. Metal components are then cemented or press-fit onto these prepared surfaces. A plastic (polyethylene) spacer between the femoral and tibial components recreates the smooth gliding surface of normal cartilage. The result is a joint with reliable pain relief and restored range of motion.

Total knee replacement is one of the most studied elective surgical procedures in medicine. Large registry data from Sweden, Australia, and the United States consistently show that 90% or more of implants remain functional at 10 years, and newer implant designs continue to improve durability. The procedure's effectiveness at relieving pain and restoring function is well established; the primary question for any individual patient is timing — ensuring the decision is made when symptoms are severe enough that the risks of surgery are clearly outweighed by the expected benefits.

What Happens During Total Knee Replacement?

Before Surgery

Total knee replacement requires more pre-operative preparation than ambulatory procedures. You will complete medical optimization — any significant cardiac, pulmonary, or metabolic conditions should be addressed with your primary care physician before surgery. Pre-operative blood work, an EKG, and possibly cardiology or anesthesia clearance are standard. A pre-operative physical therapy evaluation ("prehab") to strengthen the quadriceps before surgery has been shown to improve recovery. You will receive instructions about stopping blood thinners and certain medications.

Anesthesia

Both general anesthesia and spinal anesthesia (epidural-type block that numbs from the waist down, allowing you to remain awake but sedated) are effective options. Spinal anesthesia with sedation reduces total anesthetic drug exposure and is associated with slightly reduced blood loss and nausea in some studies. Your anesthesiologist will discuss the options based on your medical history.

Positioning and Tourniquet

You are positioned supine on the operating table. A tourniquet is applied to the upper thigh to reduce blood loss during the procedure. The leg is prepared and draped in sterile fashion.

Incision and Exposure

An incision is made over the front of the knee, typically 6–8 inches long. The quadriceps tendon and patellar tendon are reflected to expose the joint. This is the most anatomically demanding part of the approach: the surgeon must balance adequate exposure with preservation of the extensor mechanism's integrity.

Bone Preparation

Using cutting guides aligned to the mechanical axis of the leg — not the anatomical axis — precise cuts are made on the distal femur, proximal tibia, and posterior femoral condyles. The goal is to restore the normal mechanical alignment of the limb (the straight line from hip center to ankle center passing through the knee center). Modern instrumentation and, in some cases, robotic assistance provide additional precision in achieving planned alignment.

Trial Implants and Balancing

Trial implant components (testing versions of the real implants) are placed and the knee is put through range of motion. The surgeon evaluates stability in flexion and extension and adjusts soft tissue tension as needed — a process called "ligament balancing." Proper balance ensures the knee feels natural through the full arc of motion and is critical to implant longevity and patient satisfaction.

Final Implant and Fixation

The trial components are removed and the bone surfaces are prepared with bone cement (polymethylmethacrylate). The final metal femoral component, tibial tray, polyethylene insert, and patellar button are positioned and the cement pressurized and allowed to cure. Some surgeons and implants use cementless (press-fit) fixation that relies on bone in-growth; the choice depends on bone quality and surgeon preference.

Closure and Drain

The wound is irrigated, a drain may be placed, and layers are closed with sutures. A compressive dressing is applied. Patients who received spinal anesthesia will regain sensation in the leg over the following 2–4 hours.

Hospital Stay

Most patients stay 1–2 nights in the hospital. Physical therapists begin working with you the day of or day after surgery — walking with a walker and climbing stairs before discharge. Most patients are medically ready for discharge within 24–48 hours of surgery and go home or to a short-term rehabilitation facility if needed.

Recovery timeline

Frequently Asked Questions