Introduction

The knee is a joint that connects the upper and lower leg.⁸ This joint is needed for activities like walking, running, and swimming. A healthy knee can be moved from 0-150 degrees.⁸ Knee pain is one of the most common complaints which affects all age groups.⁸ Around 25% of adults are suffering from this issue.⁷ Over the past 20 years, these complaints have increased to 65%.⁷In the below text, we have discussed causes, physical therapy intervention, roles of assistive tools and adjuncts, benefits, and precautions of physical therapy. Physical therapy is a non-surgical process which will helps to cure knee pain. Different types of techniques have been used to treat knee pain they are heat therapy, ultrasound therapy, electrical stimulation therapy, manual therapy, and exercise therapy. Assistive tools and adjuncts like braces, taping, and assistive walking tools are briefly explained in terms of their roles in relieving pain. The main objective of this article is to give an account of the role of physical therapy in knee pain. Fig.1 represents the knee pain.

Causes of knee pain

Acute injuries

Meniscus injury

A catching sensation and posterior knee pain are caused by a meniscal tear (a meniscus tear is an injury to the C-shaped fibrocartilage in the knee) or a twisting injury while bearing weight.^1,7 

Collateral ligament sprain or rupture (MCL, LCL)

Pain caused by valgus [a force which pushes the knee inward and causes stress on the medial collateral ligament(MCL)] or varus [a force which pushes the knee outward and causes stress on the lateral collateral ligament (LCL)] force.⁷

Cruciate ligament sprain or rupture (ACL, PCL)

• Anterior Cruciate Ligament (ACL): Caused by a sudden pivoting injury with a pop sound, there will be swelling within 1- 2 hours⁷ 
• Posterior Collateral Ligament (PCL): Caused by sudden extreme bending or stretching and blunt trauma (injury caused forcefully by a dull object) to the anterior tibia⁷

Chronic conditions 

• Patellofemoral pain syndrome: It is an anterior knee pain which is dull and painful, caused by prolonged sitting or heading upstairs⁷ 
• Patellar tendinopathy or quadriceps (Jumper’s Knee): Caused by repetitive use due to running and jumping⁷
• Osgood-Schlatter disease or Sinding-Larsen-Johansson syndrome: anterior knee pain in adolescence spreads gradually during the rapid growth period, resulting from overuse⁷ 
• Prepatellar bursitis: Blunt trauma, repetitive injuries and infections cause swelling and patella-localised pain⁷
• Pes anserine bursitis: Blunt injury and overuse are the main causes of medial knee pain; bending and extension will worsen the pain⁷
• Lliotable band syndrome: Runners and cyclists who are involved in repetitive knee flexion or bending may experience chronic lateral knee pain⁷
• Popliteal (Baker) cyst: An isolated posterior knee pain caused by a symptomatic cyst (an abnormal fluid-filled sac)⁷
• Osteoarthritis: It is a degenerative pain which occurs in adults above 50, caused by weight bearing and relieved by rest⁷

Post-surgical pain 

• Arthrofibrosis: In total knee replacement (TKR) patients, collagen and adhesion are excessively produced, which causes pain and restricted movement²
• Component malpositioning: Post-TKR anterior knee pain occurred, which is due to changes in ligament tensions, altered kinematics, and increased retro-patellar pressure²
• Patellar maltracking: During the knee movement, the patella does not remain in the femoral groove, which leads to pain in the knee²
• Post-TKR pain is also influenced by psychological factors like somatisation dysfunction, and depressive symptoms²

Physical therapy interventions

Pain and inflammation management

Heat therapy 

• Heat therapy is also called diathermy. This method is used to treat a variety of musculoskeletal issues⁵
• This therapy is used to increase the temperature of the underlying tissue, which induces vasodilation, reduction in muscle cramps, increased cellular activity, and increased stretchability of soft tissue⁵
• Short wave diathermy(SWD) and microwave diathermy(MD) are the two methods that have been used in this therapy⁵
• In short-wave diathermy, high-frequency electromagnetic waves have been used to generate heat in a particular tissue, which is a continuous wave. Whereas microwave diathermy uses microwave to generate heat in tissue, which are lower frequency waves, and it does not penetrate muscles⁵ 
• The mechanism of microwave diathermy increases blood flow and allows oxygen and nutrients to be delivered, which promotes tissue repair⁵

Ultrasound therapy

• Ultrasound therapy is a process in which electrical energy is converted into heat energy when it is passed through a tissue⁵
• Due to the thermal properties of ultrasound therapy, there is an increase in pain, an impact on neuromuscular activity which helps muscle relaxation, helps in tissue regeneration, and a reduction in inflammation⁵
• Ultrasound therapy results in the improvement of pain and joint functioning in patients⁵

Electrical stimulation

• Electric stimulation has been proposed to decrease the muscle weakness of the quadriceps muscle and to treat knee osteoarthritis⁵
• There are various types of electrical stimulation which are currently used; they are high-frequency transcutaneous electrical nerve stimulation (h-TENS), neuromuscular electrical stimulation (NMES), low-frequency transcutaneous electrical nerve stimulation(l-TENS), interferential current (IFC), pulsed electrical stimulation (PES), and noninvasive interactive neurostimulation(NIN)⁵
• By using h-TENS electrical stimulation, there is an improvement in motor excitability and decreased voluntary muscle activation⁵
• In IFC, current has been delivered to the deeper layer of the skin, and this method may lead to a reduction in pain⁵
• The patient who has received IFC treatment has shown around 88% improvement, whereas h-TENS shows around 74% improvement⁵

Manual therapy (massage, joint mobilisation)

• Manual therapy is a technique in which muscle massage, mobilisation of affected joints and stretching have been done⁴
• Swedish body massage and knee manipulation are types of manual therapy⁴

Exercise therapy

Stretching

• Stretching exercises are the first line of therapy for the patient who is suffering from patellofemoral pain syndrome⁶ 
• Hamstring stretch is one of the exercises used for patellofemoral pain syndrome, which will reduce the pain⁶ 

Strengthening

• Strength training is the most effective non-surgical and non-pharmacological therapy⁵
• The exercises which reduce the pain of patients with knee osteoarthritis are quadriceps and hamstring strength exercises⁵
• Static quadriceps and straight leg rise are the most effective exercises which are effective for the reduction of pain⁵ 
• Hip abductor and isometric quadriceps strengthening exercises are also used to treat patellofemoral pain syndrome⁶

Patient education

• Patient education is very important in managing anterior knee pain because understanding the condition, treatment options, expectations, and barriers related to pain is crucial¹⁰
• A clear explanation about the treatment and outcomes should be given to a patient, which will reduce the anxiety, fear and confusion about the pain. This will give confidence to a patient for an upcoming treatment plan¹⁰
• The patient should be mainly educated about managing exercises and activities, which will increase their confidence and lead to an improvement in pain and function¹⁰ 

Role of assistive tools and adjuncts

Braces

• A valgus brace is commonly used in knee osteoarthritis, which neutralises the joint load on the medial compartment of the tibiofemoral joint. It will improve the pain and function of the knee⁴
• Alignment of the lower extremities has been altered by the knee brace, and it also decreases the load on the compartment of the knee. This type of brace is called a unloader brace⁵
• Unloader Brace has been used for medial knee osteoarthritis, which will improve the tibiofemoral alignment, the body load has been shifted away from the degenerated compartment and reduce the mechanical stress. By using this brace, there is a significant decrease in pain⁵

Taping

There are different types of taping, like Rigid taping, Kinesio taping, McConnell taping, and Mulligan taping.³

• Rigid taping: it is tan-coloured tape, which is usually used by athletes to reduce or prevent injury. There is a standard protocol to apply, which begins with an under wrap to reduce irritation later, rigid tape has been applied on the area of injury. This method is used to reduce pain, limit excessive joint motion, and provide proprioceptive feedback during activity³
• Kinesio taping: Kinesio tape is an elastic tape which is available in multiple colours. Kinesio tape can be applied directly on the skin without any under wrap. Kinesio tape has been designed to target multiple receptors within the somatosensory system, which targets pain reduction and promotes lymphatic drainage³
• McConnell taping: It is an adhesive type of tape which is primarily used in patients with patellofemoral pain to help the alignment of the patella. This method will give mechanical pressure to the patella, which allows it to move freely without any contact with other parts and reduces pain³
• Mulligan taping: It is an adhesive tape which is similar to rapid tape. It is a technique which uses manual force to a joint in a specific direction, and this allows painless movement in a joint which was previously painful. After mulligan mobilization a rapid tape can be applied in the same direction, which extends the benefit³

Assistive walking devices

Some of the assistive devices are widely recommended, such as a walking aid to neutralise the joint load in osteoarthritis. To reduce stress on joints, other assistive tools can be used.⁴

Benefits and outcomes of physical therapy

• Knee pain can be reduced by performing strength exercises⁵ 
• Assistive devices like walking aids have been used to neutralise the load on the knee in osteoarthritis⁴ 
• Different types of tapes have been used to reduce the pain in the knee³
• Various types of braces are used to reduce the pain, improve function and lower the mechanical stress⁵
• By performing strengthening and stretching exercises, pain in the knee will reduce, and function will improve⁵ 

Precautions

• Overweight is a major factor that causes knee osteoarthritis, and the most effective method to avoid or reduce the risk of osteoarthritis is weight loss⁹ 
• 50% of major knee injuries during sports can be successfully prevented by programs like neuromuscular and proprioceptive training⁹ 

FAQs

What is a knee?

The knee is an important connection between the trunk and the ground, which helps us to walk and run. The knee has 0-140 degrees of motion, which allows us to sit or squat

What are the different types of physical therapy?

Heat therapy, ultrasound therapy, electrical stimulation, manual therapy, and exercise therapy are types of physical therapy.

Why is patient education important?

Patient education is very important because it will reduce the anxiety, fear and confusion about the pain. This will give confidence to a patient for an upcoming treatment plan.

Summary

In the above text, there is a detailed account of the causes of knee pain and how physical therapy will aid in healing the knee pain. Causes of knee pain include acute injuries like ligament tears, meniscus injury, sprains, whereas chronic conditions like osteoarthritis, patellofemoral pain syndrome, tendinities, bursitis and post-surgical pain with knee pain. When it comes to physical therapy, different methods have been used to treat knee pain, they are heat therapy, ultrasound therapy, electrical stimulation, manual therapy, and exercise therapy. In addition to this, some assistive tools like braces and tapes have been used to get relief from knee pain. Weight loss, neuromuscular and proprioceptive training are the precautions for knee pain.