Introduction

Knee pain is a common complaint that affects people of all ages. Knee pain may be the result of an injury or a disease. 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 joint and the fact that it is an active weight-bearing joint are factors in making the knee one of the most commonly injured joints.

Pain can also occur in the knee from diseases or conditions that involve the knee joint, the soft tissues and bones surrounding the knee, or the nerves that supply sensation to the knee area. In fact, the knee joint is one of the most commonly involved joints in rheumatic diseases, including rheumatoid arthritis, reactive arthritis, gout & pseudogout, systemic lupus erythematosus, and osteoarthritis. Overuse injury to the knee can lead to inflammation of the tendon below the kneecap (runner’s knee or jumper’s knee with patellar tendinitis) and bursitis. Trauma can cause dislocation or fracture of the bones of the knee.

Signs & symptoms

• Pain
• Swelling
• Redness
• Warmth/raised temperature
• Weakness of the knee
• Popping noises
• Instability of joints
• Tenderness of the joint
• Stiffness of the joint
• Limping
• Difficulty in climbing stairs
• Locking of the knee (unable to bend the knee)
• Inability to extend the knee
• Shifting weight to the opposite knee and foot

Causes

Acute injury such as a broken bone, torn ligament, or meniscal tear

Ligament injuries like ACL (anterior cruciate ligament) injury.

Dislocation: The knee joint can be dislocated, which is a medical emergency that requires immediate attention. Knee dislocation can compromise blood flow to the leg and have other related problems. This injury often occurs during a motor-vehicle accident when the knee hits the dashboard.

Rheumatoid arthritis

Gout 

Septic arthritis (infectious arthritis)

Chronic use/overuse conditions osteoarthritis, chondromalacia, IT band syndrome, patellar syndromes, tendinitis, and bursitis.

Patellar tendinitis 

Osteoarthritis

Prepatellar bursitis

Children can develop inflammation of the point of bony insertion of the patellar tendon (Osgood-Schlatter disease).

Excess weight/obesity

Overuse

Pathophysiology

Pathophysiology depends upon the disease that causes knee pain. In each disease from rheumatoid arthritis to knee injuries, the pathophysiology is different. Yet the neurophysiology in pain stimulus can be understood with the help of recent research studies.

The neurobiological processes initiated in the joint give rise to neural signals and then decoded by the central nervous system into pain perception.

Joint innervation and nociception

Most of the weight bearing joints are richly innervated by sensory and sympathetic nerves. Postganglionic sympathetic fibres terminate near articular blood vessels, where they regulate joint blood flow through varying degrees of vasoconstrictor tone. The primary function of sensory nerves is to detect and transmit mechanical information from the joint to the central nervous system. Large diameter myelinated nerve fibres encode and transmit proprioceptive signals, which can be interpreted as being either dynamic (movement sensations) or static (position sense). Pain-sensing nerve fibres are typically less than 5 μm in diameter and are either unmyelinated (type IV) or myelinated with an unmyelinated ‘free’ nerve ending (type III). These slowly conducting fibres typically have a high threshold and only respond to noxious mechanical stimuli, and as such are referred to as nociceptors. In the rat and cat, 80% of all knee joint afferent nerve fibres are nociceptive, suggesting that joints are astutely designed to sense abnormal and potentially destructive movement.

Nociceptors are located throughout the joint, having been identified in the capsule, ligaments, menisci, periosteum and subchondral bone. The most distal segment of type III and type IV afferents is devoid of a myelin sheath and perineurium, and it is believed that this is the sensory region of the nociceptive nerve. Transmission electron microscopy revealed an hour glass shape repeating pattern along the length of type III and type IV nerve terminals, and the multiple bulbous areas exhibit the characteristic features of receptive sites. It is within these ‘bead-like’ structures on the terminals of ‘free’ nerve endings that joint pain originates.

The question of how a painful mechanical stimulus is converted into an electrical signal that can then be propagated along sensory nerves to the central nervous system is still unclear. The exposed nature of sensory ‘free’ nerve endings means that the axolemma of these fibres is probably subjected to significant stretch during joint movement. The recent identification of mechano-gated ion channels on type III and type IV knee joint afferents by electrophysiological means provided the first insight into the physiological mechanisms responsible for mechano-transduction in joints. The present theory is that movement of the joint generates shear stresses on the axolemma of the ‘free’ nerve endings, resulting in the opening of mechano-gated ion channels. This leads to a depolarization of the nerve terminal and the generation of action potentials, which are subsequently transmitted to the central nervous system where they are decoded into mechano-sensation. If a noxious movement is applied to the joint, the firing rate of the afferent nerve increases dramatically and the central nervous system interprets this nociceptive activity as pain. In addition to this cognitive aspect of arthritis pain, there is also an affective or emotional component to the disease. Patients who suffer from chronic arthritis pain exhibit clinical signs of depression and anxiety that appear to have a physiological basis. Some studies found that noxious mechanical stimuli applied to acutely inflamed joints had an excitatory effect on the firing rate of neurones in the central nucleus of the amygdala. These studies provide the first electrophysiological evidence that the amygdala is involved in transforming nociceptive information arising from arthritic joints into an emotional, painful experience.

Diagnosis

Case taking to confirm any history of trauma

Physical examination to locate the site of tenderness etc.

X ray

USG

MRI

Blood tests to rule out inflammatory diseases or medical conditions like gout.

Removal of joint fluid (arthrocentesis)

Treatments

Treatments for knee pain are as varied as the conditions that can cause the pain.

• Medications

Analgesics

NSAID’s

Anti-inflammatory

• Physical therapy

Sometimes physical therapy sessions to strengthen the muscles around the knee will make it more stable and ensure the best mechanical movements. Working with a physical therapist can help avoid injuries or further worsening of an injury.

• Injections

Injecting medications directly into your knee might help in certain situations. The two most common injections are corticosteroids and lubricants. Corticosteroid injections can help arthritis and other inflammations of the knee. They usually need to be repeated every few months. Lubricants that are similar to the synovial fluid.

• Surgery

Arthroscopic knee surgery:

It allows the surgeon look inside the knee through a few small holes and an optic fibre camera. The surgeon can repair many of the injuries and remove small pieces of loose bones or cartilage. This is a common outpatient procedure.

Partial knee replacement:

The surgeon replaces the damaged portions of the knee with artificial parts. Only part of the knee joint is replaced in this procedure.

Total knee replacement:

 In this procedure, the knee is replaced with an artificial joint.

Prognosis

The prognosis of knee pain, even severe knee pain, is usually good although it might require surgery or other interventions. It depends on the underlying causes of the pain. With modern surgical techniques, it’s possible to relieve many of the knee pain syndromes and return to an active lifestyle.

Complications

Frequently, knee pain will disappear without ever finding a specific cause. Depending on the underlying cause of the pain, the condition can progress and lead to more serious injuries or complications. Usually, these complications are long term and result in worsening pain, difficulty to walk or permanent damage to the joint.

Disease & Ayurveda

Knee pain – Jaanuruja

Nidana

Nija or aagantu reasons

Purvaaroopa

Not mentioned

Samprapti

Not mentioned

Dosha involved          – Vaata

Dooshya involved      – Asthi-sandhi, Sira-snaayu

Lakshana

Ruja    – Pain

Divisions

Not mentioned

Prognosis

Saadhya in new cases

Yaapya in chronic cases with deformity

Chikithsa

Samana

Lepana with soolaharadravyas

Parisheka with soolaha-sothahara dravyas

Upanaha with Vaataharadravyas

Sodhana

Sneha (Anhyanga)

Sweda (Potalisweda)

Vasti

Virechana

Raktamokshana

Commonly used medicines

        Sahacharadi kashayam

Rasnerandadi kashayam

Gulguluthiktakam Kashayam Tablet

Amruthaguggulu

Kaisoraguggulu

Guggulutiktaka ghrutam

Brands available

AVS Kottakal

AVP Coimbatore

SNA Oushadhasala

Vaidyaratnam oushadhasala

Home remedies

Over-the-counter pain medications can frequently alleviate the pain.

The RICE mnemonic is often helpful, especially for minor injuries:

Rest: Rest the joint, and take a break from your usually activities involving the knee joint.

Ice: Applying ice can help with pain and inflammation.

Compress: A compression bandage can help prevent swelling and help knee alignment. It should not be tight and should be removed at night.

Elevate: Elevation can help with swelling and resting of the knee. 

Diet

• To be avoided

Heavy meals and difficult to digest foods – cause indigestion.

Junk foods- cause disturbance in digestion and reduces the bioavailability of the medicine

Carbonated drinks – makes the stomach more acidic and disturbed digestion

Refrigerated and frozen foods – causes weak and sluggish digestion by weakening Agni (digestive fire)

Milk and milk products – increase kapha and cause obstruction in channels

Curd – causes vidaaha and thereby many other diseases

• To be added

Light meals and easily digestible foods

Green gram, soups, sesame oil.

Freshly cooked and warm food processed with cumin seeds, ginger, black pepper, ajwain etc

Behaviour:

Protect yourself from very hot & cold climates.

Better to avoid exposure to excessive sunlight wind rain or dust.

Avoid lifting heavy weights and other vigorous physical activities.

Maintain a regular food and sleep schedule.

Avoid holding or forcing the urges like urine, faeces, cough, sneeze etc.

Avoid climbing of stairs.

Yoga

Vigorous exercises are not allowed in painful conditions.

Only stretching, moderate walking, and mild cardio exercises are advised. Also, specific yogacharya including bhujangaasana, salabhasana, vajrasana is recommended. Caution must be there to consider the range of movement and flexibility. 

Regular exercise helps improve bioavailability of the medicine and food ingested and leads to positive health.

Yoga can maintain harmony within the body and with the surrounding system.

Salabhasana

vajrasana

Bhujangasana

exercises for leg pain

All the exercises and physical exertions must be decided and done under the supervision of a medical expert only.

Research articles

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1794504/