Anatomy and Function of the Knee

The knee connects the femur, or thigh bone, to the tibia, or shin bone. There are two joints in the knee, the tibiofemoral joint, joining the tibia and femur and the patellofemoral joint, joining the kneecap to the femur. These two joins work together to form a modified hinge joint, allowing the knee to bend and straighten the leg, while allowing it to rotate slightly from side to side. Ligaments attach bones to bones while giving strength and stability to the knee. Once stretched, ligaments tend to stay stretched and if stretched too far, they may snap. Tendons are elastic tissues that connect muscle to bones. Cartilage covers the ends of all the bones in any joint. The cartilage is kept slippery by synovial fluid and synovial membrane. Since the cartilage is smooth and slippery, the bones are able to move against this cushion easily. In a healthy knee, the rubbery meniscus cartilage absorbs shock and side forces placed on the knee, while simultaneously offering the knee joint stability and spreading out the weight that is carried by this powerful joint.

Knee Conditions and Treatment Options

One major cause of chronic knee pain and disability is arthritis. Osteoarthritis, rheumatoid arthritis, and traumatic arthritis are the most common forms of this disease. Osteoarthritis is an age-related “wear and tear” type of arthritis, where the cartilage cushioning the bones of the knee wears away. When the bones rub against each other, it causes pain and stiffness in the joint. Rheumatoid arthritis is an autoimmune disease in which the synovial membrane becomes inflamed or thickened. This chronic inflammation can damage the cartilage, leading to pain and stiffness. Post-traumatic arthritis can follow knee injury or fracture. The cartilage may become damaged and lead to knee pain and stiffness over time. Fractures of the bones surrounding the knee or tears of the knee ligaments may damage the articular cartilage over time, causing knee pain and limiting knee function.

ACL Reconstruction

The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments of the knee. The injury most often occurs when swift deceleration accompanies cutting, pivoting or sidestepping maneuvers, awkward landings or “out of control” sports play. Immediately after the injury, patients usually experience pain and swelling and the knee feels unstable. Within a few hours, the knee exhibits a large amount of swelling, a loss of full range of motion, pain or tenderness along the joint line and discomfort while walking.

Non-surgical treatment, including progressive physical therapy, patient education, rehabilitation and bracing can restore the knee close to its pre-injury state. However, additional injury may occur due to repetitive episodes of knee instability. Surgical treatment is often advised when dealing with ACL tears in combination with other injured tissue in the knee. Non-surgical treatment is most often successful in patients with partial ACL tears, no symptoms of knee instability, light manual work or sedentary lifestyle, or open growth plates in children.

When surgical treatment is chosen, ACL tears are not sutured back together. Repaired ACLs are shown to fail over time. Instead, the torn or ruptured ACL is generally replaced by a substitute graft made of tendon. Patellar tendon, hamstring tendon or quadriceps tendon from the patient, or a tendon taken from a cadaver may be used for grafting. Active adults who are involved in sports or have jobs that require pivoting, turning or heavy manual work are encouraged to consider surgical treatments. In children, ACL reconstruction should be delayed as long as possible to allow for skeletal maturity, in order to decrease risk of growth plate injury.

Your surgeon will help you determine the best approach for healing your ACL injury based on factors unique to you and your lifestyle. After surgery, the knee will be iced regularly and may be braced for 10 – 14 days. Physical therapy is a crucial part of successful ACL recovery. Goals for rehabilitation include reducing knee swelling, maintaining mobility of the kneecap, regaining full range of motion of the knee, as well as strengthening the quadriceps and hamstring muscles.

Knee Arthroscopy

Arthroscopy is done through small incisions. During the procedure, your surgeon will insert a small camera instrument (arthroscope) into the joint. This allows the surgeon to see the structures of the knee in great detail. Arthroscopic surgery may be indicated for removal and repair of torn cartilage, reconstruction of torn ACL, trimming pieces of torn cartilage, removal of loose fragments of bone or cartilage, removal of inflamed synovial tissue. Arthroscopy is less invasive than traditional surgery and often results in less pain and faster recovery time. Recovery goals include, reducing knee swelling, avoiding infection at the site of the incision, increasing weight bearing activities and gradually getting back to the normal activities of daily life. Therapeutic exercise will strengthen the muscles of the leg and knee. Formal physical therapy may be included as part of a strengthening regimen. A full return to most activities should be expected after 6 or 8 weeks. The final outcome of your surgery will be determined by the degree of damage to your knee and the physical demands of your personal lifestyle.

Total Knee Replacement

A knee replacement might more accurately be called a knee “resurfacing” because only the surface of the bones is actually replaced. In any knee replacement surgery your surgeon will first prepare the bone by removing damaged cartilage surfaces, along with a small amount of underlying bone. The damaged cartilage and bone is then replaced by metal implants that may be cemented or “press fit” into the bone. As part of your procedure, the underside of the patella (kneecap) may be cut and resurfaced with a plastic button. Finally, a medical-grade plastic spacer is inserted between the metal components to create a smooth gliding surface for movement of the knee. There are no absolute age or weight restrictions for total knee replacement surgery. Patients are evaluated on an individual basis, but may be considered for this procedure if they suffer severe pain or stiffness that limits everyday activities, moderate pain when resting, chronic inflammation and swelling that does not respond to medication, knee deformity or a failure to substantially improve after non-surgical treatments, such as; anti-inflammatory medications, cortisone injections, lubricating injections, physical therapy and other surgeries.

Uni Knee Replacement

Unicondylar knee replacement (Uni Knee)simply means that only a part of the knee joint is replaced through a smaller incision than would normally be used for a total knee replacement.

Revision Knee Replacement

Total knee replacement is one of the most successful procedures in all of medicine. In the vast majority of cases, it enables people to live richer, more active lives free of chronic knee pain. Over time, however, a knee replacement may fail for a variety of reasons. When this occurs, your knee can become painful and swollen. It may also feel stiff or unstable, making it difficult to perform your everyday activities. If your knee replacement fails, your doctor may recommend that you have a second surgery—revision total knee replacement. In this procedure, your doctor removes some or all of the parts of the original prosthesis and replaces them with new ones.

Although both procedures have the same goal—to relieve pain and improve function—revision surgery is different than primary total knee replacement. It is a longer, more complex procedure that requires extensive planning, and specialized implants and tools to achieve a good result.

After a Revision Knee Replacement, you will most likely stay in the hospital for several days. Although recovery after revision surgery is usually slower than recovery after primary total knee replacement, the type of care you will receive is very similar. Your recovery plan will most likely  include pain management, physical therapy, and prevention of blood clots and infection.  Wound care, physical therapy, blood-thinning medications and antibiotics will also be part of your recovery at home for some weeks after your procedure. Follow your doctors instructions carefully.

MAKO Partial Knee Replacement

MAKOplasty® Partial Knee Replacement is an innovative partial knee replacement procedure that is performed using a highly advanced, surgeon-controlled robotic arm system. It can be a treatment option for people suffering with either non-inflammatory or inflammatory degenerative joint disease. The goal of using robotic arm technology to perform knee replacement is to provide the utmost in accuracy for placement and alignment of implant components. The use of robotics helps your surgeon place the implants in the desired location with incredible accuracy. It is performed with the RIO® Robotic Arm Interactive Orthopedic System. RIO enables your surgeon to use a 3-D anatomic reconstruction based on a CT scan of your own knee to pre-surgically plan implant positioning. During the procedure, it provides real-time data for intra-operative adjustments to further enable me to optimally align and position implants, and accurately reproduce the surgical plan. Your surgeon will determine if you are a good candidate for this procedure, based on the specifics of your condition.