Total Knee Replacement (TKR) Pain: Symptoms, Causes, Risk Factors, Healing Cycle & Treatment
What is Total Knee Replacement (TKR)?
Total knee replacement surgery is a musculoskeletal surgical procedure that is both common and cost-effective. The surgery is performed when an individual is suffering from painful knee osteoarthritis and simultaneous reduction in the quality of life. The majority of the patients undergoing knee replacement surgery have good clinical outcomes. One of the important concerns with total knee replacement surgery is post-surgical pain relief.  Other potential complications of total knee replacement surgery include stiffness, infection, blood clot, vascular injury, instability, fracture, dislocation, pulmonary embolism, and nerve injury.  The following sections describe the symptoms and risk factors of postoperative pain along with the mechanisms of the healing cycle.
Post-Operative Pain in Total Knee Replacement Surgery
Approximately 15-30% of patients with total knee replacement suffer from persisting pain after the surgery. The post-surgical pain can be inflammatory pain, pain related to acute infection and instability or malalignment of prostheses, and second onset pain related to late infections and loosening of the components. The pain is also attributed to chronic infections. 
The symptoms of pain after total knee replacement surgery are as follows.
- Signs of inflammation such as stiffness and swelling at the joint
- Instability or weakness of the joint
- Inability to straighten the knee joint
- Excessive formation of scar tissue at the knee joint
The risk factors associated with the onset of post-surgical pain after total knee replacement surgery are as follows.
- Individuals who are overweight are likely to develop post-operative pain
- Infections increase the risk for post-operative pain
- Improper rehabilitation approach can contribute to the development of post-operative pain
- Deficiency of vitamins and minerals is also associated with an increased risk for pain after total knee replacement surgery
Normal Healing Cycle
Wound healing in the human body is made of three stages; inflammation stage, proliferation stage, and maturation stage. It is important to understand the mechanisms of the normal healing cycle prior to the discussion of chronic conditions related to the healing cycle and treatment options for pain in total knee replacement surgery. 
The first stage of the healing cycle is inflammation. The cardinal signs of inflammation include redness, pain, loss of function, warmth, and swelling. During the inflammation stage of the healing cycle, the inflammatory cells release cytokines and inflammatory mediators. The inflammatory mediators cause the immune cells to arrive at the site of injury in order to remove the injurious stimuli.
The next phase of the healing cycle is proliferation. The processes occurring in the proliferation stage are re-epithelization, angiogenesis or formation of new blood vessels, deposition of collagen synthesized by the proliferating fibroblasts, and synthesis of the extracellular matrix at the site of injury. Negative feedback mechanisms regulate the proliferation stage of the healing cycle, preventing excessive deposition of collagen and excessive formation of scar tissue. Fascia restrictions and muscle trigger points arise during this stage of the wound healing cycle.
The last stage of the normal healing cycle is the maturation stage, which marks the completion of the healing cycle. During this stage, scar formation occurs, and the wound contracts. In the scar tissue, type III collagen is replaced by type I collagen.
Healing Cycle and Chronic Conditions
In chronic conditions, the healing cycle fails to resolve. Instead, the healing cycle oscillates between the inflammation and proliferation stages. Chronic inflammation persists for a longer duration as compared to acute inflammation, which is relatively shorter as resolves with the completion of the maturation stage of the healing cycle. In chronic conditions, the healing cycle may involve the formation of scar tissue, trigger points, muscle spasm, and fascia restrictions. 
Ineffective Treatments of Knee Replacement Pain
Individuals may opt for traditional pain-relieving methods to alleviate pain associated with total knee replacement surgery. The following are ineffective therapeutic approaches for post-operative pain. Some of these methods may only provide short-term pain relief whereas some may even aggravate the symptoms of post-operative pain.
- Application of heat and ice
- Electrical stimulation of the knee joint
- Massaging and the use of foam roller at the knee joint
- Mobilization of the knee joint
- Stretching at the knee joint
- Strength exercises during the inflammation stage
Effective Treatments of Knee Replacement Pain
Effective treatments of pain associated with total knee replacement surgery focus on the healing cycle. Effective treatment and management strategies include functional training, strength exercises, resolution of the inflammation stage, and resolution of the proliferation stage.
The resolution of the inflammation stage of the healing cycle involves the use of the MagnaHeal device, consumption of an anti-inflammatory diet, and treating vitamin and mineral deficiencies. Zinc, iron, and vitamins A, B, C, and D are integral to the wound healing cycle. Countering the deficiencies of these nutrients may contribute to a normal healing cycle and alleviation of post-operative pain in total knee replacement surgery.  Magnetic therapy is also useful for the resolution of the healing cycle.  MagnaHeal device is made of neodymium and the surface is covered by anti-inflammatory materials. The magnetic force length of MagnaHeal 1 is 2 inches and that of MagnaHeal 2 is 3 inches. One may also increase the consumption of an anti-inflammatory diet that comprises fruits, legumes, vegetables, whole grains, and unsaturated fats. 
The resolution of the proliferation stage of the healing cycle involves the release of scar tissue, muscle trigger points, and fascia restrictions. A1 Tool releases aponeurotic and superficial fascia restrictions. A3 Tool releases superficial scar tissue and superficial muscle trigger points. A5 Tool releases the deep scar tissue as well as endomysium, epimysium, and perimysium fascia restrictions.
The treatment and management of post-operative pain in total knee replacement surgery involve the resolution of the inflammation and proliferation stages of the healing cycle. In addition to proper rehabilitation and strengthening exercise, one may consume a healthy anti-inflammatory diet for the resolution of the healing cycle. MagnaHeal and A1, A3, and A5 tools are also useful for the resolution of the inflammation and proliferations stages of the healing cycle.
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