Why does PAIN occur? Understand the Mechanism of Pain

Pain is an unpleasant and distressing physical sensation caused by disease or injury, which induces hurt and anxiety in those suffering from it.
There are many different manifestations of pain, ranging from short term (acute pain) to long term (chronic pain). Other classifications include pain in the internal organs (visceral pain), injured tissue (inflammatory pain), nerves (neuropathic pain), etc.

The reason for the occurrence of pain depends on the cause and kind of pain being experienced. In most cases, pain acts as a warning sign that the body has been afflicted by a disorder of some sort, which may have arisen due to internal sickness or external wounding. Acute pains are generally cured on their own through rest or simple medication. Chronic pains, on the other hand, are more complicated in nature and the treatment requires more elaborate diagnosis.

The mechanism of pain

Pain is an extremely personal and subjective experience and affects each individual to varying degrees. The pain signals, which can arise in any part of the body, travel through the spinal cord to the brain along thousands of specialized nerves and nerve fibres. In the brain, it is processed in the centres associated with anxiety, emotions, memory, appetite, etc. Signals and pain inputs are then returned from the brain to the spinal cord, which may heighten or diminish pain.

In some cases, pain may also be induced by damage to the brain and spinal cord, which happens after a stroke.
A constant barrage of pain signals may cause the cells at the end of nerve fibres to become over-sensitized. This is known as 'wind-up' and is one of the most common causes of chronic pain that occurs even though the root of the problem has been identified and treated.

The causes and effects of pain differ from case to case depending on the signals received by the brain and its interpretation. It affects the individual's day to day activities and if persistent, can also have a harmful impact on mental health and psychosis. Pain is always handled, diagnosed and treated differently in all patients by drawing out the best possible solution to the problem.





Why does PAIN occur? Understand the Mechanism of Pain

Knee pain is something that can affect anyone - irrespective of their age. While sometimes it may be of minor importance - and can easily be handled by self-care, often, lingering pain is a manifestation of some other serious underlying problem, such as arthritis. In this case, it is imperative that you consult a doctor and take appropriate measures to combat it.

Causes :

Arthritis: The chief cause of lingering knee pain, arthritis itself can be of a number of types:
 Osteoarthritis, which is a result of deterioration of cartilages due to wear and tear
 Rheumatoid Arthritis, an inflammatory chronic disorder
 Septic Arthritis, causing pain, swelling and redness.
 Gout caused due to the development of uric acid crystals in the joints
Fractures: These are caused by the breaking up of the kneecap due to falls or collisions.
ACL Injuries: Caused due to the tearing of the anterior cruciate ligament (that connects the femur and the shinbone). Especially common in sportspersons such as footballers or basketball players.
Meniscus tears: The meniscus or the rubber-like cartilage (that acts as a shock absorber) can be torn by sudden jerks or excess pressure.

Symptoms:The major symptoms of knee pain include weakness, redness, instability, stiffness or the inability to properly straighten or move the leg. Often, a deformity is also visible, such as a bone sticking out of the leg - in which case it is advisable to consult a doctor immediately.

Possible risks :Factors which include the odds of being inflicted by knee pain and cause serious complications include :
Being overweight: This exponentially increases the stress or pressure that is applied on the knee joints - even in doing mundane tasks like walking up and down stairs.
Excessive physical activity: Some activities, such as sports apply excess stress on the knees as compared to other tasks.
Loss of muscle flexibility: Tightness or weakness in muscles causes increasing number of problems in the knees.

All About Knee Pain

Knee is a hinge joint where the lower leg bone tibia meets the thigh bone femur. During osteoarthritis, cartilage or ligament defects and degenerative arthritis, knee replacement surgery is recommended world-wide to get relief from extreme pain. Knee replacement surgery, also known as knee arthroscopy, is a surgical procedure, in which the affected knee joint is replaced with synthetic material. The most likely candidates for total knee replacement are the patients with severe destruction of the knee joint coupled with progressive pain and impaired function.

Modern technological advances have made computer assisted knee replacement surgery extremely popular around the globe. In this surgery, the surgeon is assisted by a computer to remove the optimum amount and angle of the bone, which otherwise is done by inspecting manually. This is an excellent example of surgery through small incision and it eliminates the chances of human error. A perfect alignment and balance is achieved and hence longevity is also increased to 20 - 30 years. Knee replacement surgery is also specific to gender as the anatomy of male and female patients is different.

There are many types of knee replacements, most common being the total knee replacement or Total Knee Arthroplasty. In addition, there is partial knee replacement, bilateral knee replacement, revision knee replacement and knee arthroscopy.

In knee replacement surgery, the worn out surfaces of joints of knee are replaced with artificial implant of plastic and metal. The lower end of the femur bone is removed and replaced with a metal shell. The upper end of the lower leg bone (tibia) is also removed and replaced with a channelled plastic implant with a metal stem. A plastic ball is also added under the kneecap depending on its condition. These artificial components are commonly referred as prosthesis. The design of these highly flexible implants replicate knee, with the rotating knee replacement implants assist in backward and forward swing of the legs.

Patients whose knee joints have been damaged by either trauma or progressive arthritis should consider total knee replacement surgery. Post-surgical hospital stay after knee joint replacement is usually three to five days. The surgery has a very high success rate and shows dramatic improvement after a month. This improvement is most notable one month or more after surgery. The pain caused by the damaged joint is reduced significantly when the new gliding surface is constructed during surgery. Initially, patient will walk with the help of a walking aid until the knee is able to support full body weight. After six weeks, patient can walk comfortably with minimal assistance. Patients with artificial joints are prescribed to take antibiotics during the course of any elective invasive procedures including dental work. Physiotherapy is an essential part of rehabilitation and it will increase the muscle strength and patient can enjoy most activities, except running and jumping.

Knee Replacement

Your knee is a very complex structure consisting of bones, ligaments, cartilage, tendons, muscles and meniscus. Most people encounter knee pain at some point in their lives. If your knee pain is chronic in nature, then it may last for a prolonged period.

Many causes may be responsible for your knee pain. Some of the causes are stated as follows:
1. Your knee is very much prone to injuries. Knee injuries may happen due to accidents, falling down carelessly or while playing sports. The most common knee injuries that may be the cause for your knee pain are mentioned as follows: 
a) Fractures may cause you to feel pain in the areas of your knee bones.
b) Anterior Cruciate Ligament injury (ligament injury caused by twisting and a sudden motion) or Medial Collateral Ligament injury (injury to the tissue in the insides of your knee) is very common to sportspersons and may be the reason for severe knee pain.
c) Sometimes your knee bones may get dislocated from their usual alignment. This can also make you experience severe knee pain.
d) Ligament injuries, meniscus tear or tendon tear can also be responsible for your knee pain.

2. Sometimes pain in your buttock or foot region can also result in mild knee pain.

3. At times chronic problems like osteoarthritis that affects the cartilage can cause the problem of knee pain. Other chronic problems like Gout, rheumatoid arthritis can also cause severe knee pain.

4. Being overweight can also result in knee pain.
The symptoms of knee pain may be different in each case. The most common symptoms are mentioned below:
a) Stiffness of knee
b) Swelling of your knee
c) You may also feel unstable
d) Difficulty in walking or bending of your knee.
e) You may notice redness in your knee area.

Knee pain must not be ignored. It is highly recommended for you to seek advice from an orthopedic as soon as you encounter any of the above mentioned symptoms.

Suffering from Knee Pain - Know What Causes it? 

The knee is the largest joint in the human body and is a complex structure formed of bone, muscle and cartilage. Development of pain in the knees can be caused by numerous factors such as aging, injuries, diseases, dietary deficiencies, etc.

Arthritis is the most common cause of knee pain and usually affects the elderly and aged. It occurs due to an inflammation of the joint and causes pain, swelling, redness and inflexibility of the knees.

What are the factors that determine treatment method?

Diagnosis for knee pain varies from patient to patient as each case is different and must be approached differently. Some of the factors that determine the treatment method are as follows:

- Cause of the problem
- Nature and intensity of pain
- Age of the patient
- Medical history of the patient
- Diet and lifestyle of the patient

There are a number of different types of arthritis which can affect the knees in different ways and, consequently, require different types of treatment methods.

What are the various treatment methods for knee pain?

1. Conventional Remedies - These are used in case of conditions that are not too severe or chronic. It includes keeping on bed rest, using an ice pack, taking a painkiller and anti-inflammatory medicines, wearing knee braces, etc.

2. Physical Therapy - There are many stretching and strengthening exercise routines that help alleviate knee pain and treat the condition. Recovery is achieved by making the muscles around the knees stronger and increasing stability and flexibility.

3. Injections to the Knees - A number of anti-inflammatory substances and supplements, as well as lubricants, can be injected into the knee joint which helps reduce pain and makes the joint more supple.

4. Stem Cell Therapy - This involves drawing platelets from the patient's blood and injecting it into the knee joint for repairing damage caused to ligaments, tendons or cartilage.

5. Surgery - Surgical procedures for treating knee pain include partial or complete knee replacements.



What kind of treatment does your knee pain require?

Knee replacement can be extremely painful. Previously, opioids or narcotics were administered for pain relief. But excessive addition of opioids is not exactly effective for controlling pain. 

Multimodal pain management has become an important part of the perioperative care of patients undergoing total joint replacement. The principle of multimodal therapy is to use interventions that target several different steps of the pain pathway, allowing more effective pain control with fewer side effects. Many different protocols have shown clinical benefit. The goal of this review is to provide a concise overview of the principles and results of multimodal pain management regimens as a practical guide for the management of joint arthroplasty patients.

Multimodal denotes administering two or more than two types of medications that work with different mechanisms. The following are the techniques used:

Pre-operative Femoral Nerve Block: Prior to the surgery, a catheter is placed beside the femoral nerve for blocking it. This nerve is located in the upper thigh. Medication is delivered through the catheter for the nerve to be numbed for 24 hours. Thus, pain signals to the brain are blocked. This method reduces the use of narcotics and the consequent side effects.

Patient Controlled Analgesia (PCA): This method is also known as  Pain Pump . An intravenous pump is used to administer pain relief medications, such as oxymorphone or morphine, after the surgery. The control button of the machine could be pressed, by the patient for 6 to 10 times per hour. The machine is used for two post-operative days.

Oral Medications: The oral medications include Non-Steroidal Anti-Inflammatory drugs or NSAID; such as Celebrex which is similar to aspirin, structurally. Alternatively, acetaminophen, such as Tylenol or its equivalent composition, can also be used.

Acetaminophen: It acts on the Central Prostaglandin Synthesis and relieves the patient of pain through multiple mechanisms.

Epidural Analgesia: It produces lower pain scores and involves less time for achieving physical therapy goals. However, this is subject to side effects such as dizziness, urinary retention and itchiness.

Gabapentinoids: These medications include membrane stabilizers such as Gabapentin and Pregabalin.

The objective of multimodal treatments is to provide quick relief to the patient and immediately so. Earlier the rehabilitation, more successful will be the knee replacement surgery.

Multimodal Pain Relief After Total Knee Replacement

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