Patellofemoral pain syndrome

Patellofemoral pain syndrome, also known as runner's knee, is a condition that causes pain in the front of the knee or around the kneecap (patella). It is a common cause of knee pain in adolescents and adults under 60 years old, affecting both men and women, though women are more prone to developing patellofemoral pain syndrome. The condition is often associated with activities that put stress on the knee, such as running, jumping, and squatting, but it can also occur in individuals who do not engage in high-impact sports. Understanding the causes, symptoms, and treatment options for patellofemoral pain syndrome is essential for effectively managing the condition and preventing further complications.

What is Patellofemoral Pain Syndrome?

Patellofemoral pain syndrome occurs when the cartilage under the kneecap is stressed, either due to overuse or poor alignment of the kneecap. The kneecap is a small triangular bone at the front of the knee that moves along a track at the end of the thighbone (femur), providing leverage for the front thigh muscles (quadriceps) to straighten the leg. In patellofemoral pain syndrome, pain is typically felt in or around the anterior knee and intensifies during weight-bearing activities that involve knee flexion, such as squatting, sitting, climbing stairs, and running. Symptoms can develop gradually over time or occur suddenly and may include a dull ache under the kneecap, a painful grating or creaking sensation, and sometimes a clicking or grinding noise when bending or straightening the knee. Patellofemoral pain syndrome is often multifactorial, resulting from a combination of overuse, anatomical or biomechanical abnormalities, muscular weakness, and imbalance or dysfunction.

Patellofemoral pain syndrome, also known as runner's knee, retropatellar pain syndrome, or patellofemoral disease, is characterised by a range of symptoms primarily affecting the front of the knee and kneecap area. Key symptoms of this patellofemoral pain disorder include:

• Pain located under or around the kneecap (patella)

• Pain that worsens during activities like climbing stairs, squatting, running, and jumping

• Pain after sitting for prolonged periods with knees bent

• Grinding or clicking sensations when bending and straightening the knee

• Tenderness when touching the kneecap

The severity of patellofemoral pain syndrome symptoms can vary and may involve one or both knees. Individuals often describe the pain as a dull ache that can intensify to a sharp pain during certain activities. Understanding these patellofemoral pain syndrome symptoms is key to recognising the condition and seeking appropriate treatment.

Several factors related to knee mechanics, physical activity, and individual predispositions can contribute to the development of patellofemoral pain syndrome.

The primary causes include:

• Overuse from excessive stress on the knee during vigorous activities like jogging, squatting, and stair climbing

• Malalignment of the kneecap, causing abnormal tracking in the trochlear groove and increased pressure on the patellofemoral joint

• Weakness in the thigh muscles along with tight hamstrings or Achilles tendons

• Poor foot support from unsupportive footwear or foot issues affecting gait

In addition to these main causes, other factors can also play a role in the development of patellofemoral pain syndrome:

• Direct trauma to the kneecap from a fall or blow

• Sudden increases in physical activity intensity or duration

• Participation in sports involving repetitive knee bending like running, volleyball, or basketball

• Abnormal anatomical structure such as flat feet, high-arched feet, or slight misalignment of the legs

Patellofemoral pain syndrome is a common condition that affects numerous individuals. Several risk factors can contribute to the development of this patellofemoral pain disorder, including:

• Age: Patellofemoral pain syndrome is more prevalent in teenagers and young adults, particularly those in their second and third decades of life.

• Sex: Women have a higher likelihood of developing patellofemoral pain syndrome compared to men, with a ratio of approximately 2:1.

• Activity level: Engaging in sports that involve running, jumping, and repetitive knee movements increases the risk of patellofemoral pain syndrome. Runners are especially susceptible, with patellofemoral pain syndrome accounting for 16 to 25 percent of all injuries in this group.

• Malalignment and altered biomechanics: Issues such as increased standing Q angle, flat feet, subtalar pronation, genu valgum or varus, and lateral tibial torsion can contribute to the development of patellofemoral pain syndrome.

• Patellar hypermobility: Excessive movement of the patella can lead to improper tracking and increased stress on the patellofemoral joint.

• Muscular imbalances: Weakness or improper firing patterns in muscles like the quadriceps, particularly the Vastus Medialis Obliquus (VMO), and hip abductors can disrupt normal patellar tracking.

• Overuse: Increased workload or sudden changes in training intensity, frequency, or duration can overload the patellofemoral joint, resulting in pain.

• Poor training techniques: Inappropriate running techniques, such as overstriding or poor foot strike patterns, can increase stress on the patellofemoral joint.

• Trauma: Direct or indirect injuries to the patellar area, including patellar subluxation or dislocation, can cause patellofemoral pain syndrome.

• Muscle and soft tissue tightness: Tightness in the iliotibial band, quadriceps, hamstrings, and gastrocnemius muscles can exert excessive forces on the patella, contributing to pain.

Preventing patellofemoral pain syndrome involves a holistic approach combining lifestyle adjustments, proper training techniques, and maintaining optimal lower limb strength and flexibility. Key strategies include:

• Thorough warm-up and cool-down routines before and after exercise

• Gradually increasing training intensity and duration to avoid overloading the joint

• Choosing supportive, well-fitting footwear appropriate for the activity

• Incorporating cross-training and varying exercise types to minimise repetitive stress

• Maintaining a healthy body weight to reduce load on the knees

• Regularly stretching to promote flexibility, especially of the quads, hamstrings and calves

• Strengthening the quadriceps, hip muscles and core to improve knee stability

• Using proper form and technique during sports and activities

• Allowing adequate rest and recovery between training sessions

Accurate diagnosis of patellofemoral pain syndrome is essential for developing an effective treatment plan. Doctors rely on a combination of clinical examination and diagnostic tests to identify patellofemoral pain syndrome and rule out other potential causes of knee pain.

1. Clinical examination

A thorough clinical examination is the first step in diagnosing PFPS. This includes:

• Patient history: The doctor will inquire about the onset, duration, and nature of the knee pain, as well as any associated symptoms like swelling, clicking, or instability. They will also assess the patient's activity level, training habits, and any recent changes in physical activity.

• Physical examination: The doctor will perform a comprehensive physical examination of the knee, focusing on the patellofemoral joint. They will assess the alignment of the patella, palpate for tenderness, and evaluate the range of motion, strength, and flexibility of the surrounding muscles. Special tests, such as the patellar apprehension test or the patellar grind test, may be performed to assess patellar stability and elicit pain.

2. Imaging tests

In some cases, imaging tests may be ordered to confirm the diagnosis of PFPS or rule out other conditions:

• X-rays: Plain radiographs can help assess the alignment of the patellofemoral joint, detect any bony abnormalities, and rule out conditions like osteoarthritis or fractures.

• Magnetic Resonance Imaging (MRI): An MRI can provide detailed images of the soft tissues around the knee, including the cartilage, ligaments, and tendons. It can help identify any structural abnormalities or soft tissue injuries that may be contributing to the patellofemoral pain.

3. Other diagnostic tests

Occasionally, additional tests may be performed to further evaluate the knee and guide treatment decisions:

• Gait analysis: A gait analysis can help identify any abnormal movement patterns or biomechanical issues that may be contributing to the patellofemoral pain syndrome.

• Electromyography (EMG): An EMG can assess the activity of the muscles around the knee, particularly the quadriceps, to identify any imbalances or abnormal firing patterns.

Managing and treating patellofemoral pain syndrome typically involves a multifaceted approach combining conservative measures aimed at alleviating pain, restoring joint mobility, and strengthening the muscles supporting the knee. Non-surgical patellofemoral pain syndrome treatments include:

• Activity modification: Stopping or adapting activities that worsen symptoms

• The RICE protocol: Rest, ice, compression and elevation in the acute phase

• Medications: Short courses of NSAIDs to reduce inflammation and pain

• Physical therapy: Exercises to strengthen the quads, hips and core while improving flexibility

• Orthotics and bracing: Shoe inserts and knee supports to optimise alignment and stability

Surgery is rarely needed and reserved for severe cases unresponsive to conservative management. Surgical options include arthroscopy, cartilage debridement, lateral release and tibial tubercle transfer. Implementing preventive strategies is key in managing this condition long-term.

While mild patellofemoral pain syndrome symptoms can often be self-managed initially, it is important to know when to seek medical advice. Consider consulting a doctor if:

• Knee pain is severe, persistent or worsening despite home treatment

• Pain significantly limits daily activities or sports participation

• The knee is swollen, red, hot to the touch or giving way

• There is a visible deformity or marked change in appearance of the knee

• You have a fever in addition to knee pain and swelling

• Symptoms have not improved after a few weeks of conservative management

Your doctor can perform a thorough evaluation to confirm the diagnosis and rule out other conditions that may mimic patellofemoral pain syndrome, such as a meniscus tear, osteoarthritis or patellar tendinopathy. This may involve a physical exam, imaging tests and occasionally blood work.

Based on the assessment, your doctor can recommend an individualised treatment plan, which may include physical therapy, orthotics, medications or referral to an orthopaedic specialist if surgery is being considered.

• Patellofemoral pain syndrome, commonly known as runner's knee, is characterised by pain around or behind the kneecap, often exacerbated by activities such as running, climbing stairs, and prolonged sitting with bent knees. Symptoms can include a dull ache, grinding sensations, and tenderness around the patella.

• Patellofemoral pain syndrome is typically multifactorial, arising from a combination of overuse, biomechanical abnormalities (like malalignment), muscular weaknesses (particularly in the quadriceps and hip abductors), and previous injuries. Factors such as excessive training or improper footwear can also contribute to the development of this condition.

• Diagnosis of patellofemoral pain syndrome is primarily based on patient history and physical examination, focusing on symptom patterns and ruling out other knee issues. Common diagnostic tests may involve assessing pain during specific movements like squatting or stair climbing.

• Conservative treatment approaches are most effective, including rest, ice application, NSAIDs, physical therapy (strengthening and stretching exercises), and activity modification. In some cases, orthotics or knee bracing may be recommended.

• The prognosis for patellofemoral pain syndrome is generally good, with many patients experiencing symptom relief through conservative measures. Factors influencing a poorer prognosis include older age, bilateral symptoms, and hypermobility of the patella.