Decoding Knee Replacement Surgery: A Comprehensive Guide to Restoring Mobility and Quality of Life

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  • Decoding Knee Replacement Surgery: A Comprehensive Guide to Restoring Mobility and Quality of Life

Knee joint, the most complicated and the biggest joint of the body. It is more vulnerable to pain and swelling as it takes the entire body weight and acts as a shock absorber. According to a research conducted by NCBI, the prevalence of knee pain in Singapore is 22.8%. Knee pain can be caused by sudden injury, an overuse injury, or by an underlying condition, such as arthritis. Treatment will vary depending on the cause. Symptoms of knee injury can include pain, swelling, and stiffness. As there are so many different structures in and around the knee, it is difficult to list all the possible injuries leading to knee pain and swelling. The location and severity of knee pain may vary, depending on the cause of the problem. Osteoarthritis is the most common cause of chronic knee pain. It occurs when the cartilage of the knee becomes damaged. The knee is actually not a simple hinge (like in a door) nor is it a pure sliding (like some machines). It is a rolling hinge. The related movement is a combination of flexion/extension and a small amount of medial/lateral rotation. Flexion and extension occur between the femur (capitulum) and tibia (tibial plateau). During closed chain motion, the femur rolls and slides anteriorly on the tibia during flexion and rolls and glides posteriorly during extension. And these patterns are reversed during extension.

Overview of Knee Joint and its Functions

The knee is a synovial joint, which means it is a joint surrounded by a capsule that contains lubricating synovial fluid. The major stabilizing muscles of the knee are the quadriceps muscles on the front of the thigh and the hamstring muscles on the back of the thigh.

There are two types of cartilage in the knee. The menisci are the tough and rubbery shock absorbers between the bones. Articular cartilage is the smooth substance lining the bones which allows the bones to move against each other without causing damage to the bones.

The knee is actually made up of four bones. The femur (thigh bone) articulates with the tibia (shin bone) at the tibiofemoral joint. The patella (kneecap) articulates with the femur at the patellofemoral joint. The fibula is the other bone in the lower leg. The joint where the femur articulates with the tibia is a hinge joint, and the joint where the femur articulates with the patella is a gliding joint. The remaining joint is the tibiofibular joint.

An injury can affect any of the ligaments, bursae, or tendons surrounding the knee joint. Injury can also affect the ligaments, cartilage, menisci (plural for meniscus), and bones within the joint. The complexity of the design of the knee and the fact that it is an active joint are factors in making the knee one of the most commonly injured joints.

Knee pain is a common complaint that affects people of all ages. Knee pain may be the result of an injury, such as a ruptured ligament or torn cartilage. Medical conditions including arthritis, gout, and infections also can cause knee pain.


Symptoms of Knee Pain

Knee pain can manifest alongside a range of diverse symptoms, varying from person to person. These symptoms encompass swelling, which can arise immediately after injury or gradually from extended use, often indicating internal knee issues; painful clicking sounds, potentially signifying torn structures like cartilage or meniscus, though painless clicking is common and generally harmless; knee stiffness, occasionally linked with swelling but sometimes occurring on its own, usually signalling an underlying serious knee problem; a sensation of the knee easily giving way, prevalent in those with ligament injuries or weakened muscles from inactivity; and instances of the knee becoming locked in one position, frequently attributed to meniscus tears. The loss of knee function becomes especially noticeable during activities such as stair climbing or squatting, rendering such actions difficult or impossible for individuals with knee problems.

Causes of with Knee Pain

Another common knee injury is an anterior cruciate ligament (ACL) injury. This usually occurs in a sports injury with a sudden twisting movement. People often hear a popping sound and the knee will suddenly give way. This may be quite painful and cause the knee to swell. This type of injury is not limited to only sports and can also occur in the elderly due to the degeneration of the ligament.

An acute injury may cause bleeding into the joint, resulting in swelling and severe pain. The most common injury is a broken bone, which can cause continuous pain even when the patient is resting. A meniscus tear will also cause pain and swelling in the patient’s knee. A tear can lead bits of meniscus to interfere with the normal functioning of the knee, causing it to ‘give way’, particularly if the knee is in a twisted position. This can cause looseness from the swelling due to weakness in the quadriceps. The ‘give way’ feeling often leads to further injury of the knee and/or secondary injuries in other joints.

Knee pain and swelling can be due to many different causes, ranging from an injury to a medical condition. It is something that is very common and can happen to anyone.


Understanding the diagnostic process

The physician first takes a detailed medical history. You will be asked to explain the type of pain you are experiencing, when the pain started, the mechanism of injury, and how the pain has affected your lifestyle and activity level. The answers to these questions provide important information that will help the physician make a diagnosis. If the knee swells, it is useful to remove the accumulated fluid by aspirating it with a needle. Analysis of the fluid is helpful in diagnosing the problem. A plain x-ray may be taken in the office to help determine the nature of the problem. MRI is a non-invasive test that can provide a thorough 3-dimensional picture of the knee joint. This can help diagnose problems that do not show up on x-ray, and can be useful in determining the best course of treatment. A consultation with the surgeon is necessary for a thorough evaluation of the knee problem. The surgeon can interpret the diagnostic studies and use them, along with a physical exam, to determine the best course of treatment to alleviate the knee pain.

Importance of consulting an orthopaedic surgeon

Orthopedic surgeons have specialized training in treating knee problems, great and small. There is a common misconception that all orthopedic surgeons are the same. To put it simply, this is not the case. This is a group of medical professionals with a broad range of experience and training. It is to your advantage to find one who has specific training and experience in the diagnosis and treatment of knee problems. Studies have shown that patients who get a second opinion before surgery have better outcomes and in some cases, surgery can be avoided altogether. Various studies have indicated that a large number of patients who seek orthopedic care do so unnecessarily. In these instances, pain can often be managed with simple measures to increase function. Step one in considering surgery is to determine the feasibility of non-operative versus operative treatment. Whatever the decision, the patient and the doctor should explore all options. This is an informed decision-making process based on a clear understanding of the treatment options, and the risks and benefits associated with each option. A surgeon who is skilled in the diagnosis and non-operative treatment of knee problems has a diverse “toolbox” from which to select the best treatment option for each individual. Duration of recovery from any given surgery can vary. A patient who has a good understanding of what to expect during the recovery process, and what the realistic goals are for recovery, is more likely to be satisfied with the final outcome.

Non-surgical options for pain relief

Options for nonsurgical interventions include a wide range of treatments from the very basic to more involved procedures. The simplest form of nonsurgical care is the use of an assistive device such as a cane or single crutch. This can offload the affected area and serve to reduce pain. Weight loss has also been proven to be an effective way to reduce symptoms of knee OA. Studies indicate that for every pound lost, there is a fourfold reduction in load exerted on the knee for each step taken. This provides an enormous benefit to the patient as the load exerted on the knee across a normal day is estimated to be at least three to six times body weight. This means that a five pound loss would reduce the load exerted on the knee by 15-30,000 pounds in just one day. Weight loss can be achieved through diet and exercise programs or by involvement in more formal weight loss programs. High quality evidence exists for the use of a structured exercise program to improve pain and function in patients with knee OA. This can include aerobic, resistance, or aquatic-based programs and it may be most beneficial to have these programs supervised by a physical therapist. Step one of the treatment of knee OA would also involve a comprehensive education and self-management program. This should be integrated into all aspects of nonsurgical care and the patient should be actively involved in making all decisions about their care. This is important due to the chronic nature of knee OA and the fact that there is no cure. What may be effective once can differ from what is effective at another time. Finally, various medications and bracing options are available, and often serve as adjuncts to primary nonsurgical interventions.

While some patients might be more inclined to agree to a non-operative method for their care, it is also known that some patients may switch from operative to non-operative interventions for the treatment of their knee condition. This could be due to various reasons, such as changing circumstances in their life, insurance considerations, or personal choice. It is also logical to assume that a patient who has undergone a surgical intervention for their knee pain would also benefit from some of these treatment options during their rehabilitation phase.

Surgical interventions for knee pain management

Realignment osteotomy: This procedure is typically considered in younger, more active individuals who have a specific type of leg alignment problem that leads to wear on mainly one side of the knee. It is a surgical procedure where a cut is made into the tibia (high tibial osteotomy) or femur (femoral osteotomy) to realign the leg so that the weight is shifted away from the damaged part of the knee. High tibial osteotomies are typically done with arthroscopy procedures as well. A realignment osteotomy takes several months to recover from and is often followed by rehabilitation to regain full function of the knee.

Arthroscopy: This is a surgical procedure that is performed to evaluate and treat a variety of knee conditions. It is a recommended surgical option if your doctor feels that the less invasive treatment options are unlikely to help your damaged joint. The procedure has gained in popularity due to the smaller incisions, faster recovery times, and more accessible nature of treating multiple conditions within the knee. During an arthroscopy, your surgeon will make small incisions and then insert a small camera and possibly some tiny instruments to work within the joint. Common surgical procedures done during an arthroscopy may include removing loose damaged cartilage, trimming unhealthy edges of meniscus cartilage, removing inflamed synovium, and tightening an ACL or PCL ligament with reconstructive surgical techniques.

Surgery may be advised when a specific diagnosis is made on the reason for your knee pain that can be corrected with a surgical procedure. If considering surgery, there are now many surgical options depending on your age, the specific anatomic problem, and the expected level of activity following surgery. It is important to discuss your condition with your doctor to fully understand your specific diagnosis and the treatment options available to you.

Rehabilitation and physical therapy

Rehabilitation following an injury or surgery is usually divided into several phases. Initially, the focus is on reducing swelling and pain. This is followed by a restoration of range of motion in the joint, developing muscular strength and endurance, and finally functional and proprioceptive training before the individual returns to their previous activities. Your surgeon and physical therapist will be able to explain and guide you through the rehabilitation process that is most suited to you and your lifestyle.

– Specific exercises: to restore range of motion and strength and to return to more normal functional and recreational activities.

– Manual therapy: including massage and manipulation, along with modalities such as ultrasound and electrical stimulation.

– Bracing: for patients with instability and to delay or provide an alternative to surgery.

– Activity modification: Specially tailored instructions to patients to avoid re-injury or the development of chronic problems.

Rehabilitation and physical therapy are extremely important for successful recovery from any injury, medical intervention, or surgical procedure. Your orthopaedic surgeon and/or physical therapist may make use of a variety of modalities to help speed your recovery. These include:

Specific Conditions and Prevention

Iliotibial band syndrome (ITBS) is a common cause of lateral knee pain in athletes, and while it has been seen in a variety of sports, it is most frequently reported in runners and cyclists, particularly those with large training volumes. The condition is most commonly associated with overuse and causes pain that may be severe and intense, particularly when running. ITBS is the most common cause of lateral knee pain in runners, and if left untreated, it can result in a chronic condition.

In considering the multitude of conditions that affect the knee joint, two of the most common will be examined here: arthritis and iliotibial band syndrome. Knee arthritis is a form of joint disorder that involves inflammation of one or more joints. The most common type of knee arthritis is osteoarthritis, a degenerative disease that affects the cartilage and underlying bone and has characteristic clinical features of pain, stiffness, and restricted function. The effects of arthritis can be crippling, and while a variety of management strategies exist, there is no cure for this condition.

Exploring knee arthritis and its impact

Rheumatoid arthritis is an autoimmune disease and its affects the synovial lining of the joint and cause inflammation and swelling. When inflamed, the synovium thickens and produce chemicals that breakdown bone and cartilage. If inflammation persists, damage will occur to the articular cartilage which causes the ligaments to weaken and joint alignment is lost. This then leads onto secondary osteoarthritis.

Osteoarthritis is a condition that affects the articular cartilage that lines the knee joint. Articular cartilage is a smooth, slippery tissue that absorbs shock and allows the joint to move smoothly. When a person suffers from osteoarthritis, this cartilage becomes frayed and worn out, the joint then becomes painful and stiff as the bone underneath the lost cartilage thickens and grows spurs. Osteoarthritis often affects one side of the knee more than the other, it can also be isolated to one compartment such as the inner aspect of the knee. When this occurs it is known as unicompartmental arthritis.

Knee arthritis is one of the commonest problems of the knee. There are three different types of arthritis that can affect the knee. The first is osteoarthritis, this is a degenerative “wear and tear” type of arthritis that becomes increasingly common with age. The second is rheumatoid arthritis, a systemic immune condition that affects the synovium causing damage to the articular (joint surface) cartilage. The third is a meniscus transplantation of arthritis due to previous meniscus removal or injury.

Understanding the role of the iliotibial band

Iliotibial band (ITB) syndrome is normally caused by excessive friction of the iliotibial band on the lateral femoral condyle. This rubbing creates pain that can be sharp or intense on the outside of the knee and sometimes higher on the lateral aspect of the thigh. It can also be a dull ache in the same area. Pain is often worse in the acute stage and may prevent a runner from continuing activity. The ITB is a thick band of fascia that originates from the Tensor Fascia Latae and Gluteus Medius muscles and has fibrous attachments from muscles as far down as the Vastus muscles of the quadriceps. The ITB runs down the lateral aspect of the thigh and crosses the knee, inserting into the lateral tibial plateau. The ITB helps stabilize the knee during early stance phase of gait when the heel strikes the ground and during the stance phase of the gait cycle. Friction of the ITB is more likely to occur when the knee is in a 30-degree flexion angle. This happens to be the point of the stance phase of gait when the knee is internally rotating, while the tibia is externally rotating. This twisting motion of the knee (tibia) and the repetitive flexion and extension of the knee can cause this friction of the ITB and thus irritate and inflame it. This overuse injury frequently occurs in long distance runners and those involved in activities requiring excessive knee flexion and extension. The ITB is a thick band with poor vascularity and thus heals relatively slowly. This makes this an overuse injury that has a slow onset and a long resolution time.

Preventive measures for maintaining knee health

In a study regarding the relation of recreational and occupational activities to knee osteoarthritis, it was found that occupational activities such as regular stair climbing, lifting heavy loads, and frequent prolonged standing are associated with an increased risk of osteoarthritis. However, the study also reports that regular participation in light exercise has a protective effect against symptomatic knee osteoarthritis. Light exercise strengthens the muscles that support the knee joint and is crucial in maintaining knee joint stability. A well-rounded exercise program that includes high and low impact activities as well as exercise that focuses on flexibility, balance, and agility can enhance athletic performance, help prevent knee injury, and maintain healthy knees. High-risk noncontact and indirect contact sports such as soccer and basketball have higher anterior cruciate ligament injury rates compared to low-risk sports. Measures can be taken to reduce the risk of knee injury in athletes participating in these sports. Changes in exercise regimens and sport activities, plenty of rest and recovery time, and refraining from exercise when experiencing pain or swelling in the knee can prevent the occurrence of and further aggravation of knee problems.

Maintaining an active lifestyle is important for both the physical and mental well-being of an individual. Regular physical activity is proven to reduce the risk of heart disease, cancer, high blood pressure, and obesity. However, overtraining and intense physical activity can lead to or exacerbate knee problems. Certain changes can be made to equipment, training regimens, and exercise routines to reduce the risk of injury. Some sports medicine experts recommend that being overly aggressive in exercise is not the best way to become physically fit. More cautious training regimens and exercises can be just as effective and are less likely to cause injury. Avoiding exercises that place excessive stress on the knee will also help preserve knee health. These activities include frequent deep knee bends and downhill running.


What are the different types of orthopaedic treatments available for knee pain?

Individualized treatment plans for knee problems encompass a variety of options, spanning medication, lifestyle modifications, knee bracing, physiotherapy, pain procedures, ligament surgery, keyhole surgery for meniscus and cartilage issues, and knee replacement for severe osteoarthritis. Both surgical and non-surgical solutions are available to address specific needs.

Are there any lifestyle changes one can make to help reduce or manage chronic knee pain?

If you can maintain a healthy weight, engage in low-impact exercises, practice proper posture, and avoid activities that strain the knees, it can positively impact your knee health and overall mobility.

Is physiotherapy a recommended approach to managing chronic and severe cases of knee pain?

Yes, physiotherapy is often recommended for patients experiencing knee pain. It is part of treatment plans, which can also include medications and surgical or non-surgical methods. Physiotherapists provide education, personalized exercises, manual therapy, and supplementary approaches like hydrotherapy and acupuncture to improve health, mobility, and prevent injuries.

How can I tell if my knee pains are caused by a medical condition or injury? 

An orthopaedic surgeon can diagnose the cause of your medical condition. The evaluation of knee pain involves a medical interview, knee examination, X-rays, and potentially MRI scans to determine the underlying cause, including issues with alignment, ligaments, or meniscus.

Where can I find a knee pain doctor Singapore or a knee pain specialist Singapore? Where can I find more information about knee pain Singapore and knee pain treatment Singapore?

The Orthopaedic and Pain Practice is here to address your musculoskeletal needs. Our team is well-versed in addressing a variety of orthopaedic conditions through minimally-invasive techniques and traditional surgery.  At The Orthopaedic & Pain Practice, we know that pain can limit your pursuit of health. Let us help you relieve your pain and restore motion to your life.



Dr Yong Ren’s Profile

Dr Yong Ren graduated from the National University of Singapore’s Medical faculty and embarked on his orthopaedic career soon after. Upon completion of his training locally, he served briefly as an orthopaedic trauma surgeon in Khoo Teck Puat hospital before embarking on sub-specialty training in Switzerland at the famed Inselspital in Bern.

He underwent sub-specialty training in pelvic and spinal surgery, and upon his return to Singapore served as head of the orthopaedic trauma team till 2019. He continues to serve as Visiting Consultant to Khoo Teck Puat Hospital.

Well versed in a variety of orthopaedic surgeries, he also served as a member of the country council for the local branch of the Arbeitsgemeinschaft für Osteosynthesefragen (Trauma) in Singapore. He was also involved in the training of many of the young doctors in Singapore and was appointed as an Assistant Professor by the Yong Loo Lin School of Medicine. Prior to his entry into the private sector, he also served as core faculty for orthopaedic resident training by the National Healthcare Group.

Dr Yong Ren brings to the table his years of experience as a teacher and trainer in orthopaedic surgery. With his expertise in minimally invasive fracture surgery, pelvic reconstructive surgery, hip and knee surgery as well as spinal surgery, he is uniquely equipped with the tools and expertise necessary to help you on your road to recovery.

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Sarah Taylor

Obstetrics & Gynaecology