Causes of Knee Pain

Knee pain can arise from various causes, ranging from acute injuries to chronic conditions

It's essential to consult with a healthcare professional for an accurate diagnosis and appropriate management of knee pain. Depending on the cause and severity of your symptoms, treatment options may include rest, physical therapy, medications, injections, bracing, or surgery. Early intervention and comprehensive care can help alleviate knee pain and restore function, allowing you to resume your daily activities and maintain an active lifestyle.

common causes of knee pain

  • Osteoarthritis is a degenerative joint disease characterized by the breakdown of cartilage in the knee joint. As cartilage wears away, bones may rub against each other, leading to pain, stiffness, and swelling in the knee.

  • Acute injuries such as ligament sprains, meniscal tears, and fractures can cause knee pain. These injuries often result from sports activities, falls, or accidents and may lead to instability, swelling, and difficulty bearing weight on the affected knee.

  • Activities that involve repetitive movements or excessive stress on the knee joint, such as running, jumping, or kneeling, can lead to overuse injuries. Common overuse injuries include patellar tendinitis (runner's knee) and iliotibial band syndrome, causing pain and inflammation around the knee.

  • PFPS, also known as "runner's knee," is a common cause of anterior knee pain, especially among athletes and active individuals. It occurs when the patella (kneecap) does not track properly over the femur (thigh bone), leading to pain behind or around the patella during activities like squatting, climbing stairs, or prolonged sitting.

  • Rheumatoid arthritis is an autoimmune disorder that can affect multiple joints in the body, including the knees. In RA, the immune system attacks the synovium (joint lining), causing inflammation, pain, stiffness, and joint deformity over time.

  • Bursae are fluid-filled sacs that cushion and lubricate joints, including the knee. Bursitis occurs when these sacs become inflamed due to repetitive motion, direct trauma, or infection, resulting in localized pain, swelling, and tenderness around the knee joint.

  • Injuries to the knee ligaments, such as the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), or lateral collateral ligament (LCL), can cause knee instability, swelling, and pain, particularly during activities involving sudden changes in direction or impact.

  • The meniscus is a rubbery cartilage that acts as a shock absorber between the femur and tibia. Tears in the meniscus can occur due to sudden twisting or rotational movements of the knee, leading to pain, swelling, stiffness, and difficulty fully extending or flexing the knee joint.

  • Excess body weight puts added stress on the knee joint, increasing the risk of developing osteoarthritis and other knee-related conditions. Obesity can exacerbate existing knee pain and limit mobility, making it challenging to engage in physical activities without discomfort.

  • Certain medical conditions, such as gout, pseudogout, patellar dislocation, osteonecrosis, and tumors, can also cause knee pain. These conditions may require specialized diagnostic tests and treatments to address the underlying cause of knee pain effectively.

Bone on Bone

Understanding "Bone on Bone" in the Knee: What You Need to Know

Welcome to our patient-focused resource dedicated to helping you understand the concept of "bone on bone" in the knee. If you've been diagnosed with knee osteoarthritis or suspect you may have this condition, understanding what it means when healthcare professionals refer to "bone on bone" can empower you to make informed decisions about your joint health and treatment options.

What Does "Bone on Bone" Mean?

"Bone on bone" is a term commonly used to describe the advanced stage of knee osteoarthritis (OA) where there is significant loss of cartilage within the knee joint. Cartilage serves as a protective cushion between the bones, allowing for smooth and pain-free movement of the joint. In knee osteoarthritis, the cartilage gradually wears away over time, leading to a situation where the bones of the knee joint come into direct contact with each other, hence the term "bone on bone."

Understanding what it means when healthcare professionals refer to "bone on bone" in the knee is essential for individuals affected by knee osteoarthritis. While this term signifies advanced cartilage loss and significant joint damage, there are various treatment options available to manage symptoms and improve quality of life. By working closely with healthcare providers and exploring appropriate treatment strategies, individuals can effectively address the challenges associated with "bone on bone" in the knee and maintain an active and fulfilling lifestyle.

Causes of "Bone on Bone" in the Knee

Several factors can contribute to the development of "bone on bone" in the knee, including:

  • The most common cause of "bone on bone" in the knee is osteoarthritis, a degenerative joint disease characterized by the breakdown of cartilage. As cartilage wears away, the bones of the knee joint may rub against each other, resulting in pain, inflammation, and reduced mobility.

  • Acute injuries to the knee, such as ligament tears, meniscal tears, or fractures, can accelerate the progression of osteoarthritis and lead to "bone on bone" changes in the joint if left untreated.

  • Genetic predisposition may increase the risk of developing osteoarthritis and experiencing severe cartilage loss in the knee joint, contributing to the "bone on bone" phenomenon.

Symptoms of "Bone on Bone" in the Knee

When the knee joint reaches the stage of "bone on bone," individuals may experience the following symptoms:

  • Pain in the knee joint, especially with weight-bearing activities or movement, is a hallmark symptom of advanced knee osteoarthritis. The pain may be sharp, stabbing, or achy and can significantly impact daily activities and quality of life.

  • The knee joint may feel stiff, particularly after periods of inactivity or rest. Swelling around the knee joint may also occur due to inflammation and irritation of the surrounding tissues.

  • As osteoarthritis progresses and cartilage loss worsens, individuals may notice a significant decrease in knee joint mobility and range of motion. Activities such as walking, climbing stairs, or bending the knee may become increasingly challenging.

Treatment Options for "Bone on Bone" in the Knee

While there is no cure for advanced knee osteoarthritis with "bone on bone" changes, several treatment options can help manage symptoms and improve quality of life:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroid injections, and pain relievers may help alleviate pain and inflammation associated with knee osteoarthritis.

  • Targeted exercises and physical therapy modalities can improve joint flexibility, strengthen supportive muscles, and enhance mobility in the affected knee.

  • Maintaining a healthy weight can reduce stress on the knee joint and slow the progression of osteoarthritis. Losing excess weight through diet and exercise may help alleviate symptoms and improve joint function.

  • Using assistive devices such as braces, canes, or orthotic inserts can provide support and stability to the knee joint, reducing pain and improving mobility.

  • In severe cases of knee osteoarthritis with "bone on bone" changes and significant functional impairment, surgical interventions such as total knee replacement (arthroplasty) may be considered to replace the damaged joint with an artificial implant.

Traumatic and Overuse injuries of knee lead to OA

Traumatic or overuse injuries to the knee can contribute to the development of osteoarthritis (OA) through various mechanisms, including direct damage to joint structures, altered biomechanics, and accelerated cartilage degeneration.

Traumatic or overuse injuries to the knee can increase the risk of developing osteoarthritis through mechanisms such as direct damage to joint structures, altered biomechanics, and accelerated cartilage degeneration. Addressing these factors through appropriate treatment and rehabilitation strategies is essential for mitigating the risk of OA development and preserving joint health in individuals with knee injuries.

how injuries can lead to OA

  • Traumatic injuries, such as ligament tears, meniscal tears, or fractures, can cause immediate damage to the structures within the knee joint, including cartilage, ligaments, and menisci. Overuse injuries, on the other hand, result from repetitive stress or strain on the knee joint over time, leading to microtrauma and gradual wear and tear of joint tissues. Both types of injuries can disrupt the integrity of the joint, compromise its stability, and accelerate the degenerative process.

    A study published in the "Journal of Orthopaedic Research" (2016) found that traumatic knee injuries, such as anterior cruciate ligament (ACL) tears, significantly increased the risk of developing post-traumatic osteoarthritis (PTOA) later in life. The study demonstrated that individuals with a history of traumatic knee injuries were at a higher risk of developing PTOA compared to those without such injuries.

  • Traumatic or overuse injuries can alter the biomechanics of the knee joint, leading to abnormal loading patterns and increased stress on certain areas of the joint. For example, ACL tears can result in knee instability and abnormal joint movement, while overuse injuries such as patellar tendinitis can cause imbalances in muscle strength and coordination around the knee. These biomechanical changes can predispose the knee joint to accelerated wear and tear, contributing to the development of osteoarthritis over time.

    Research published in the "American Journal of Sports Medicine" (2018) examined the association between abnormal biomechanics and the development of knee osteoarthritis following ACL injury. The study found that altered movement patterns and increased loading on the knee joint were significant risk factors for the progression of osteoarthritis after ACL injury, highlighting the importance of addressing biomechanical factors in OA prevention and management.

  • Traumatic or overuse injuries can accelerate the degeneration of articular cartilage within the knee joint, leading to the development of osteoarthritis. Cartilage serves as a protective cushion between the bones of the knee joint, allowing for smooth and pain-free movement. When cartilage is damaged or worn away due to injury, the underlying bone may become exposed and vulnerable to further damage, resulting in pain, inflammation, and joint degeneration characteristic of osteoarthritis.

    A systematic review published in the "British Journal of Sports Medicine" (2017) examined the association between ACL injury and the development of osteoarthritis. The review concluded that ACL injury was a significant risk factor for the early onset and progression of osteoarthritis, with evidence suggesting that the extent of cartilage damage at the time of injury influenced the long-term risk of OA development.

Meniscal injuries and OA

Meniscal injuries of the knee are commonly associated with an increased risk of developing osteoarthritis (OA).

Meniscal injuries of the knee can increase the risk of developing osteoarthritis through mechanisms such as loss of meniscal function, altered joint mechanics, and inflammatory responses. Early recognition and appropriate management of meniscal injuries are crucial for minimizing the risk of OA development and preserving joint health in individuals with knee injuries.

how meniscal injuries can lead to OA

  • The menisci are C-shaped cartilage structures that serve as shock absorbers and stabilizers within the knee joint. When a meniscal injury occurs, such as a tear, the structural integrity of the meniscus is compromised, leading to a loss of its ability to distribute forces evenly across the joint. This can result in increased stress on the articular cartilage, leading to accelerated wear and tear and ultimately contributing to the development of OA.

    A prospective cohort study published in the "American Journal of Sports Medicine" (2010) followed individuals with meniscal tears for 16 years to assess the long-term risk of OA development. The study found that patients with meniscal tears, particularly those involving the medial meniscus, were at a significantly higher risk of developing radiographic evidence of knee OA compared to those without meniscal injuries.

  • Meniscal injuries can alter the biomechanics of the knee joint, leading to abnormal loading patterns and increased stress on the articular cartilage. For example, a meniscal tear can disrupt the normal congruence between the femur and tibia, resulting in increased contact pressures on the cartilage surfaces during weight-bearing activities. Over time, this can lead to cartilage degeneration and the development of OA.

    A systematic review and meta-analysis published in the "British Journal of Sports Medicine" (2018) examined the association between meniscal tears and the risk of knee OA. The review found that meniscal tears, particularly those involving the medial meniscus, were associated with an increased risk of developing radiographic evidence of knee OA, highlighting the importance of addressing meniscal injuries to prevent OA progression.

  • Meniscal injuries can trigger inflammatory responses within the knee joint, leading to the release of pro-inflammatory cytokines and enzymes that contribute to cartilage degradation and joint inflammation. Chronic inflammation is a known risk factor for the development and progression of OA, as it can accelerate the breakdown of cartilage and impair its ability to repair and regenerate.

    Research published in the "Journal of Orthopaedic Research" (2019) investigated the inflammatory response following meniscal injury and its role in the pathogenesis of OA. The study found that meniscal tears induced a significant increase in inflammatory mediators within the joint, including interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α), which are known to promote cartilage degradation and contribute to OA progression.

Knee pain after surgery

The percentage of patients who experience persistent pain after knee surgery can vary depending on factors such as the type of surgery, underlying conditions, and individual differences in pain perception and response to treatment. While many patients experience significant pain relief and improved function following knee surgery, a subset may continue to experience persistent or recurrent pain despite surgical intervention. 

Studies highlight that while knee surgery can provide significant pain relief and functional improvement for many patients, a proportion may continue to experience persistent pain and functional limitations following surgery. Identifying risk factors for persistent pain and implementing targeted interventions to address ongoing symptoms are important considerations in optimizing outcomes for patients undergoing knee surgery.

studies that have investigated the prevalence of persistent pain after knee surgery

  • A study published in the journal "Pain Medicine" (2018) examined the prevalence of persistent pain after total knee arthroplasty (TKA) in a large cohort of patients. The study found that approximately 20% to 30% of patients experienced persistent pain following TKA, even after successful surgery and rehabilitation.

  • Research published in "Arthroscopy: The Journal of Arthroscopic & Related Surgery" (2015) investigated the long-term outcomes of arthroscopic partial meniscectomy (APM) and arthroscopic debridement for knee osteoarthritis. The study reported that up to 25% of patients experienced persistent pain and functional limitations two years after arthroscopic knee surgery.

  • A systematic review and meta-analysis published in the "British Journal of Sports Medicine" (2019) evaluated the prevalence of persistent pain after anterior cruciate ligament (ACL) reconstruction. The review found that approximately 20% to 30% of patients experienced persistent knee pain one to two years after surgery, with factors such as younger age and concomitant meniscal injury associated with higher rates of persistent pain.

  • A study published in the "Journal of Bone and Joint Surgery" (2018) examined the outcomes of various surgical treatments for patellofemoral joint disorders. The study reported that approximately 20% to 30% of patients experienced persistent pain and functional limitations following patellofemoral joint surgery, with outcomes varying depending on the specific procedure performed.

  • Research published in the "Journal of Bone and Joint Surgery" (2018) investigated the prevalence of persistent pain after total knee replacement (TKR) surgery. The study found that approximately 10% to 20% of patients experienced moderate to severe persistent pain six months to one year after TKR, with factors such as preoperative pain intensity and psychological distress associated with increased risk of persistent pain.