To better understand the knee’s architecture and function and the degenerative changes associated with arthritis, this post has been compiled to assist you in getting ready for total knee replacement surgery and give instructions for post-operative care. Total knee replacement surgery aims to improve your quality of life by eliminating your pain, allowing you to return to your regular activities, and restoring your knee’s functionality.
Anatomy and Function of the Knee
The three bones that comprise the knee joint are the femur (thighbone), the tibia (shinbone), and the patella (kneecap). The knee may be described as a modified hinge joint, similar to the hinge on a door. However, the knee bends back and forth like a hinge and has a complex rotational component that occurs with flexion and extension of the knee. The knee is a more weight-bearing joint held together by muscle ligaments and other crucial soft tissue. Cartilage is the material inside the joint that provides shock absorption to the knee during weight-bearing activities such as walking or stair climbing.
The Arthritic Knee
Arthritis in the knee joint occurs due to degeneration of the cartilage in your knee. Osteoarthritis is commonly called “wear and tear arthritis” or degenerative arthritis and is the most common cause of total knee replacement surgery. Due to osteoarthritis, the cartilage in the knee breaks down time, resulting in a severely damaged joint surface with bone rubbing on the bone. This process may occur due to previous trauma to the joint, ligament instability, or abnormal stresses to the joint.
Rheumatoid arthritis is an inflammatory process that results in erosion of the articular cartilage and subsequent damage to the knee joint surface.
Non-surgical Treatment of the Arthritic Knee
Listed below are several non-operative, conservative options to consider for the treatment of the arthritic knee:
- Lifestyle Modification: Losing weight, avoiding aggravating activities, modifying exercise to low-impact activities only.
- Exercises: Specifically prescribed exercises to improve strength and flexibility without exacerbating pain.
- Anti-inflammatory Medications: Designed to decrease swelling in the joint and provide temporary pain relief.
- Corticosteroid Injection: Powerful anti-inflammatory agent injected directly into the joint.
- 5. Joint Fluid Therapy: A series of injections directly into your knee, designed to improve lubrication in the joint.
- Glucosamine/Chondroitin: Dietary supplement that may relieve arthritic pain.
- Bracing: Used to provide external stability to the knee joint.
- Arthroscopic Surgery: Minimally invasive procedure to remove debris or repair torn cartilage.
Reasons for Knee Replacement Surgery
Total knee replacement surgery is considered when all other conservative measures have failed to provide successful intervention and may be performed for the following reasons:
- To relieve pain
- To improve joint stability
- To improve alignment and correct bone deformity
- To maximize the quality of life 5. To optimize activities of daily living
TKR Surgery is a standard procedure for more than 600,000 people worldwide annually. With recent advancements in surgical technique and implant design, patients have experienced dramatic improvement in knee pain, function, and quality of life. Furthermore, most patients can expect their implants to last up to a decade or more, allowing for years of active, healthier, pain-free living.
Preparation for Knee Replacement Surgery
Once you and your orthopedic surgeon have decided to proceed with surgery, several activities must occur before surgery, including the following:
- Initial Surgical Consultation: Preoperative X-rays complete past medical and surgical history and a full list of all medications and allergies (prescription, over-the-counter, vitamin supplements).
- Complete Physical Examination: Your internist or family physician will determine if you are in the best condition for surgery.
- Blood Donation: A transfusion may be necessary after surgery; therefore, you may wish to donate blood before surgery.
- Physical Therapy: Instruction in an exercise program to begin before surgery and an overview of the rehabilitation process after surgery will better prepare you for post-operative care.
- Preparation for the Hospital: you may want to bring the following items:
- Clothing: underwear, socks, t-shirts, and exercise shorts for rehabilitation.
- Footwear: walking or tennis shoes for rehab, slippers for a hospital room.
- Walking Aids: walker, cane, wheelchair, or crutches if used before surgery
- Insurance Information
- Evening before Surgery:
- Do not eat or drink after midnight.
- Shower (with 5-minute scrub to a surgical area with special soap provided).
- Prepare your belongings and review the complete knee booklet.
Preoperative Procedures
This section will give you a brief overview of the activities that will occur on the day of surgery: your surgery.
- You will be admitted to the hospital, typically the morning of
- A fin assessment of vital signs will be taken.
- A clean in hospital gown will be provided.
- An IV will be started to give you fluids and medication during and after the procedure.
- An elastic stocking may be provided to decrease the like hood of blood clots.
- You will be asked to empty your bladder.
- All jewelry, dentures, contacts, and nail polish must be removed.
- The surgical leg will be scrubbed and shaved in preparation for surgery.
- The anesthesiologist will discuss the type of anesthesia that will be used.
- You will be taken into the operating room.
Total Knee Replacement
Implant Components
In the knee replacement procedure, each prosthesis comprises four parts. The tibial component has two elements and replaces the top of the shin bone or tibia. This prosthesis is made up of a metal tray attached directly to the bone and a high-density plastic spacer that provides the bearing surface
The femoral component replaces the bottom of the thigh bone or femur. This component also replaces the groove where the patella or kneecap rides.
The patellar component replaces the surface of the knee cap, which rubs against the femur. The patella protects the joint, and the resurfaced patellar button will slide smoothly on the front of the joint. In some cases, surgeons do not resurface the patella.
Bearing Surfaces
One of the keys to a successful implant is its ability to withstand the rigors of daily activity, and central to that is the quality of the artificial surfaces that slide against each other or articulate in the new joint. In knee implants, bearing surface options have been somewhat limited over the last few decades. The standard substance used for the femoral component is cobalt chrome, a metal alloy typified by its toughness and biocompatibility. However, even this high-quality industry standard has its shortcomings. Over time, this metal surface can become roughened by bone and bone cement particles trapped between the femoral component and the plastic tibial insert.
When rubbing against the plastic component up to two million times yearly, this roughened surface can wear out your implant more quickly. When that happens, you must undergo surgery to replace the plastic piece, the femoral component, and possibly even the tibial component. For this reason, implants have been shown to last between 10 and 15 years in the human body.
The most exciting material to enter orthopedics in recent years is OXINIUM [oxidized zirconium.) This tremendous new material combines the strengths of ceramic and metal, such as wear-reduction and strength. Still, it does not have the weaknesses, such as limited implant options and the possibility of fracture.
Zirconium is a biocompatible metal, similar to titanium. When the zirconium alloy undergoes a unique heating process, the surface of the metal transforms into a ceramic. Even though the new ceramic surface is 4,900 times more abrasion resistant than cobalt chrome, it retains the toughness and flexibility of the underlying metal.
Because it can achieve this remarkable reduction in implant wear without sacrificing strength as actual ceramic components do, OXINIUM® implants have the potential to last significantly longer, thus possibly reducing the need for future corrective surgeries. When articulating on standard plastic tibial components, OXINIUM knee implants reduce wear by 85 percent compared to cobalt chrome.
The Procedure
Knee replacement surgery typically takes between one and two hours to complete. This section will provide you with a brief, easy-to-understand description of the surgical procedure:An incision is made extending from the thigh, past the inside edge of the kneecap, and down to the shinbone.
- The end of the femur is shaped in preparation for sizing the femoral trial component.
- The top of the tibia is shaped for proper sizing of the tibial trial component.
- The trial units are put in place and the appropriate implant size is selected.
- The knee is assessed for alignment, stability, and range of motion.
- The underside of the knee caps prepared and patella trial is selected.
- The trial units are removed and the final femoral, tibial, and patella components are implanted.
- The incision is closed, a drain is put in, and the post-operative bandaging is applied.
Postoperative Care
After your surgery is completed, you will be transported to the recovery room for close observation of your vital signs, circulation, and sensation in your legs and feet. As soon as you awaken and your condition is stabilized, you will be transferred to your room. Below is an example of what you may see when you wake up:
- You will find a large dressing applied to your incision in order to maintain cleanliness and absorb any fluid.
- There may be a drain placed near your incision in order to record the amount of drainage being lost from the wound.
- You may be wearing elastic hose, and/or a compression stocking sleeve designed to minimize the risks of blood clots.
- Your doctor may prescribe a PCA (patient-controlled analgesia) that is connected to your IV. The unit is set to deliver a small, controlled flow of pain medication and is enacted when you firmly press the button on your machine. Press the button anytime you are having pain. 5. You may have a catheter inserted into your bladder as the side effects of anesthesia often make it difficult to urinate.
Preventing Complications
Complications can occur in a small percentage of patients, as with all major surgical procedures. Below is a list of potential complications and steps you can take to prevent their occurrence:
- Thrombophlebitis: also known as deep vein thrombosis (DVT), this problem occurs when the large veins of the leg form blood clots and, in some instances, become lodged in the capillaries of the lung and cause a pulmonary embolism. The following steps may be taken to avoid blood clots:
- Bloc-thinning medication (anticoagulants)
- Elastic stockings (TED hose)
- Foot and ankle exercises to increase blood flow and enhance venous return in the lower leg.
IMPORTANT: If you develop swelling, redness, pain, and tenderness in the calf muscle, report these symptoms to your orthopedic surgeon or internist immediately.
- Infection: Although great precaution is taken before, during, and after surgery. Infections do occur in a small percentage of patients following knee replacement surgery. Steps you can take to minimize this risk include the following:
- Monitor your incision closely and immediately report any redness, swelling, tenderness, increased drainage, foul odor, persistent fever above 100.4 degrees orally, or increasing pain.
- Take your antibiotics as directed and complete the recommended dosage duration.
- Strictly follow the incision care guidelines your surgeon recommends.
- Pneumonia: Because your lungs tend to become “lazy” due to the anesthesia, secretions may pool at the base of your lungs, leading to lung congestion or pneumonia. The following steps may be taken to minimize this risk:
- Deep breathing exercises: A simple analogy to illustrate proper deep breath is to “smell the roses and blow out the candles.” In other words, inhale through your nose, and exhale through your mouth at a slow and controlled rate.
- Incentive spirometer: This simple device gives you visual feedback while perform your deep breathing exercises. Your nurse or respiratory therapist will demonstrate the proper technique.
- Knee stiffness: In some cases, the mobility of your knee following surgery may be significantly restricted, and you may develop a contracture in the joint that will cause stiffness during walking or other activities of daily living. The following steps must be taken to maximize your range of motion following surgery:
- Early physical therapy (Day 1 or 2) to begin range of motion exercises and walking program.
- Edema control to reduce swelling (ice, compression stocking, and elevation).
- Adequate pain control so you can tolerate the rehabilitation regime.
Rehabilitation Following Knee Replacement Surgery
The rehabilitation process following total knee replacement surgery can be pretty painful. However, if you commit to following your program and overcoming the challenges in rehab, you will succeed in meeting the goals you set when deciding on surgery. To meet the goals of knee replacement surgery, you must take ownership of the rehab process and work diligently on your own and with your physical therapist to achieve optimal clinical and functional results. The following outline will summarize the process you will adhere to during rehabilitation:
1. In the Hospital
Ambulation with a walker or crutches (weight-bearing status determined by your surgeon)
Range of motion exercises
- Edema control (ice, compression, elevation)
- Instruction in a home exercise program
- Discharge goals are as follows:
- Independent getting in and out of bed
- Independent in walking with a walker or crutches
- Independent in walking up and down three steps
- Independent in your home exercise program
- Ability to bend your knee 90 degrees
- Ability to fully straighten your knee
2. At Home:
- Begin ambulation with a cane as tolerated.
- Keep the incision clean and dry; watch closely for signs of infection.
- Continue the home exercise program.
3. Outpatient Physical Therapy:
- Advanced strengthening program, adding weights as tolerated
- Stationary cycling Walking program
- Aquatic therapy program
4. Long-term Rehabilitation Goals:
- Range of motion from 100-120 degrees of knee flexion.
- Mild or no pain with walking or other low-impact physical activities. Independent with all activities.
- Independent with all activities of daily living.
