Pain at the medial compartment of the knee is most frequently caused by three specific forms of arthritis: Kellgren and Lawrence defined osteoarthritis as pain on most days and certainly hardening of the knee in people aged over 40 years, and radiographic change of joint space narrowing with a definitive osteophyte. This later definition may misclassify some causes of pain at the medial knee. It is not unusual that assessment of whether inner knee pain is due to arthritis can be indistinct and studies have usually included adults with knee pain as knee OA is such a universal disorder and pain can be an inclusion of multiple other disorders.
Total knee arthroplasty, or TKA, is a famous orthopedic procedure which involves reconstruction of the knee joint. It was first systematically pioneered by Dr. John Insall and the first implant was produced in 1971. TKA is regarded as one of the most successful procedures in the field of medicine, with a survivorship of the implant at about 95% at 20 years. In 2003, 400,000 TKAs were performed in the US and it is expected that the magnitude of TKA will rise to 600,000 per year in 2015. It is indicated for severe rheumatoid arthritis, osteoarthritis, and other knee-related disorders, including meniscal damage, ligament damage, and other articular cartilage disorders. The procedure involves resurfacing the damaged knee surfaces with metal and plastic components to restore the alignment and function of the knee.
What is Total Knee Arthroplasty?
Rheumatoid arthritis is an inflammatory arthritis where synovium that lines the joint becomes thickened and inflamed. This can lead to loss of function of the knee and pain; it can also cause severe deformities. To ensure that the implant is most effective for patients with rheumatoid arthritis, it is best used for those who are experiencing severe pain or who have problems with function of the knee, and can also be constructive for those with severe deformities. Total Knee Arthroplasty has been shown to decrease pain severity in patients with rheumatoid arthritis, and significant functional improvement has been reported post TKA in comparison with non-surgical management.
Total Knee Arthroplasty (TKA), again largely referred to as a total knee replacement, is a surgical procedure to resurface a knee damaged by arthritis. Metal and plastic parts are used to cap the ends of the bones that form the knee joint, along with the kneecap. This surgery is typically applied to the knee joint when osteoarthritis has impaired the cartilage in the knee, rheumatoid arthritis, as well as when the knee has suffered a critical form of trauma other than arthritis. The aim of TKA is to reduce pain and restore function to a damaged knee.
Causes of Inner Knee Pain
Pain on the internal aspect of the knee can be due to several pathologies. Overuse or sudden twisting motions can cause irritation and inflammation of the gracilis or medial hamstring tendons, or the tendons on the inside of the knee. These injuries are usually minor and can be treated with rest and physical therapy. A more significant injury is a tear of the medial meniscus. This C-shaped cartilage acts as a cushion and shock absorber in the knee. One half of the medial meniscus is usually attached to the joint capsule and can often get trapped between the femur and tibia during a twisting injury, leading to a tear of the meniscus and sometimes of the cartilage on the bone surfaces. This type of injury, if untreated, can lead to degenerative arthritis of the knee, as the loss of a portion of the meniscus and damaged articular cartilage are the predisposing factors for the development of arthritis. Finally, and most seriously, a ligament injury can cause the tibia to slide too far forward on the femur. This can cause damage to the smooth cartilage surfaces on the bones and is a common mechanism of injury which can lead to the development of arthritis. Diagnosis of the source of inner knee pain is usually done with physical examination followed by MRI of the knee. Depending on the results, the treatment will vary. Tendonitis and minor tendon tears are usually treated with rest and physical therapy. A tear of the medial meniscus can sometimes heal on its own with rest or will require arthroscopic surgery to trim the torn portion; partial removal of the meniscus is done to prevent it from catching again on the joint surfaces. A torn meniscus in an older individual can sometimes cause arthritis due to the loss of the shock-absorbing function of the meniscus, so removal of a larger portion of the meniscus may be a predisposing factor for a knee replacement at a later date. Patients with chronic tibial subluxation or cartilage damage will usually need treatment to help realign the tibia on the femur and prevent further damage to the articular surfaces. This may involve a brace and physical therapy, or in more serious cases, surgery to reconstruct the damaged ligaments.
Importance of Proper Treatment
Inner knee pain treatment is extremely important to ensure a successful recovery and a positive outcome following a total knee arthroplasty, and at all times it has to be remembered that TKA is purely a pain relieving operation and not one that is designed to ultimately improve function. All medical as well as surgical forms of treatment, whether they are directed at the cause of the pain or the site of the pain, must be aimed at minimizing the impact of the cause of the pain to allow maximum function with comfort. Failure to accurately diagnose as well as treat the cause of the pain can result in an unfavorable outcome due to persistent pain and functional limitation of the knee joint. There are numerous causes of knee pain, some of which have similar presentations as well as pain referrals to other forms of knee pathology. A common situation is the patient who already has advanced knee osteoarthritis and undergoes a TKA, but has minimal benefit and sometimes increased pain following the procedure. It must be noted that the result of the arthroplasty may have been very successful in achieving its aim to prolong the survival of the prosthesis and maximize the function of the joint but did not resolve a separate pain generator in a knee with multifactorial pain. Failure to achieve this aim can sometimes result in patient dissatisfaction, and if the site and cause of new pain is identified, it is often possible to give benefit to the patient with conservative treatment at the pain site.
Total Knee Arthroplasty Procedure
Evaluation of the patient’s medical history is of utmost importance. Both diabetes and Parkinson’s disease may alter the functional results of a total knee arthroplasty. The use of a preoperative systematic approach has reduced the risk of complications. This system includes better selection of patients, patient counseling, patient optimization, and newer surgical techniques and implant designs. Most patients have learned about the surgery from acquaintances who have had successful results and have experienced life-altering benefits. An informal survey of 62 inpatients ages 54 and younger, including 25 males and 37 females, was taken. Of the 62 patients, 37 or 60% had total knee replacements. Thirty-four or 92% of the patients were happy with their results and would recommend the surgery to others with end-stage knee arthritis. Patients with bilateral knee involvement typically will have both knees replaced; however, the surgeries are often performed 6-12 months apart.
Current surgical techniques and instrumentation have led to well over 90% success rates. The goal of the joint replacement is to relieve pain with restoration of function allowing the patient to return to a more active lifestyle. With the aging population hoping to stay active, joint replacements are being done in older patients with physiologic ages that can tolerate more activity than their actual chronologic age would predict. This has created more demand to accomplish lasting functional results. Patients with the following conditions are in need of a total knee replacement: severe pain and disability secondary to degenerative arthritis, rheumatoid arthritis, or posttraumatic arthritis. Global range of motion around the knee joint is markedly reduced to a range of motion less than 45 degrees to greater than 15 degrees from full extension. Furthermore, patients with severe varus or valgus deformities greater than 15 degrees make for good candidates for the benefits and possible correction of a total knee arthroplasty.
Preoperative Evaluation
A comprehensive history and a thorough physical examination are the cornerstones of the preoperative evaluation. Co-existing medical conditions affecting the patient’s ability to tolerate the surgical operation and to potentially influence the outcome of the arthroplasty should be evaluated. These may include but are not limited to cardiovascular disease, pulmonary disease, diabetes, chronic steroid dependence, immunosuppression, compromised renal or hepatic function, and a history of infections. Although no absolute contraindications currently exist for knee arthroplasty, some of these medical conditions may require additional preoperative medical clearance and optimization prior to surgical intervention.
Although there is currently no standardized indication or absolute contraindication for total knee arthroplasty, the decision for surgical intervention is typically multifactorial and individualized for each patient. Preoperative evaluation of a patient must take into account patient age, occupation, level of activity, and expectations for recovery. The evaluation should focus on the severity of symptoms, and objective clinical and functional status of the affected knee. Radiographic changes seen on plain x-rays or other imaging studies should correlatively be shared with clinical symptoms.
Surgical Technique
Implant component positioning and limb alignment are determined by the use of intramedullary guides and extramedullary referencing systems as previously described (Zaricznyj, 1986). The constrained intramedullary alignment systems differ from conventional techniques by allowing the bone cuts to be made without removing excessive amounts of bone from the femur or tibia. This can be beneficial for the final prosthesis fixation and the potential need for revision surgery. The extramedullary systems use the epicondyles and the tibial plateau as bony references and have been used successfully on both the tibia and the femur to determine limb alignment and overall component positioning. An imageless navigation system or a modified version of the system can also be employed to improve the accuracy of these implants.
The traditional patient position for knee replacement on a standard operating table places unnecessary stress on the uninvolved muscles and ligaments around the hip and knee, which can delay recovery. Additionally, it can be difficult to achieve proper implant positioning and limb alignment (which is essential for appropriate leg length, motion, and overall function) with this patient position. Suboptimal alignment can compromise the durability of the implants and the ligament balancing, which is essential for a good functional outcome. Both the mini-midvastus and the limited quadriceps approaches are performed with an orthopedic surgical table. This is a distinctive advantage to the conventional medial parapatellar approach and is unique to the minimally invasive technique. The table allows the ability to flex and extend the knee through a full range of motion and adjust the limb position throughout the surgery. This can be helpful for the exposure, component positioning, and overall equilibrium of the soft tissues in the knee. An unconstrained leg can do the same thing it is intended for.
Postoperative Care and Rehabilitation
Wound management is critical in preventing infection after total knee arthroplasty. With a postoperative infection rate of less than 2%, infection remains one of the most significant complications after TKA. Infection can lead to multiple surgeries, prolonged antibiotic therapy, and possible permanent joint damage. To avoid infection, the wound must be kept clean and dry, and dressings should be changed daily. Progressive strengthening exercises and gait training should continue throughout the rehabilitation process. The patient’s progress can be monitored by improvement in strength and gait mechanics. High-level function such as running and jumping are generally not recommended, as they add significantly increased load across the joint and can cause implant loosening and deterioration. These extremes of function are typically not needed in the arthritic elderly population and can lead to premature prosthesis failure.
Avoiding potential postoperative complications and restoring the patient to full function is the primary goal following total knee arthroplasty. Although debated in the literature, the postoperative and rehabilitation program can have a significant impact on the patient’s recovery and return to prior level of function. In addition, the rehabilitation process can vary depending on the type of prosthesis implanted. However, there are several key components when discussing the postoperative care of the TKA patient: wound management, deep vein thrombosis prophylaxis, continuous passive motion, early motion and weight bearing, and strengthening.
Treatment Options for Inner Knee Pain
It is generally agreed that the best non-surgical treatment for inner knee pain, due to damage to the meniscus, is a supervised exercise program by a physiotherapist. This exercise program involves strengthening the muscles around the knee, particularly the quadriceps (thigh) muscles, which reduces the load carried by the meniscus. Exercises would also be done to stretch the hamstring muscles and iliotibial band as tightness in these muscle groups can predispose to inner knee pain. Other methods for the treatment of a torn meniscus are not always successful. Recent studies have shown that knee bracing is not effective, and although an injection of hyaluronic acid may relieve pain, it does not improve the condition of the meniscus. Physiotherapy to strengthen the quadriceps muscles is also the best non-surgical treatment for patellofemoral pain. This can be successful in 40-80% of cases. High tibial osteotomy is a surgical procedure to realign the leg to shift load from a damaged part of the knee to a part with more intact cartilage. This method is not commonly used today because of the success of total or unicompartmental knee replacement in older people and the lack of proven long-term benefits of this surgery for younger people with specific types of leg alignment and damage to knee cartilage.
Outer knee pain and inner knee pain might have different treatment plans, so it can be said that inner knee pain should be treated in a different way than the treatment of outer knee pain. If the symptoms are not too severe, simple home treatments for knee joint pain may be successful. The most common treatment for pain at the side of the knee and inflammation is the R.I.C.E regime: Rest, Ice, Compression, Elevation. If a specific activity has caused the pain, it may be beneficial to switch to a different form of exercise until the pain has subsided.
Non-Surgical Treatments
Injections of various substances around the patella. This includes corticosteroids, viscosupplementation and more recently, the use of autologous blood injections.
Use of non-steroidal anti-inflammatory drugs.
Physiotherapy. Includes strengthening of the quadriceps and hip muscles, correction of abnormal lower limb alignment, taping and bracing, patellar mobilisation and stretching or massage of tight structures around the knee and in the iliotibial band.
Weight loss in overweight patients.
Modification of activity to avoid painful positions. This may be as simple as changing from activities that cause high levels of pain to those that cause less pain. For example, an athlete who is a keen cyclist but who experiences high levels of PFI pain may receive relief of symptoms by changing to swimming as an alternative form of cardiovascular exercise.
Surgical Treatments
Another option is to undergo a realignment osteotomy. This is a preventative measure for those who are considered high risk for knee arthritis and knee replacement. This is usually caused by a genetic predisposition to having abnormally shaped legs or being overweight. High stress activity and physical performance are often the precursors which result in knee arthritis and inner knee pain. An osteotomy involves cutting and repositioning the tibia or the femur to shift the weight-bearing load to the unaffected side of the knee. This will alleviate the pressure on the worn-out area of the knee and prevent further damage to the articular cartilage.
Arthroscopy is a minimally invasive surgical procedure which involves a small camera being inserted into the knee joint. The camera is attached to a long thin scope which allows the surgeon to explore the inside of the knee and diagnose the problem. If a problem is found, the surgeon can make 1 or 2 small incisions around the knee and insert instruments to correct the issue.
Based on the nature and cause of the inner knee pain, there are several surgical options to help correct the problem. Some surgical treatments are seen as a last resort and should only be considered after a thorough discussion with your surgeon and consideration of alternative treatment options.
Recovery and Rehabilitation
Activities of daily living are started either the day of or the day after surgery. Early ambulation is strongly encouraged as long as excessive force and weight bearing on the foot and leg opposite to the surgical leg are avoided. In physical therapy, the patient will work on regaining full knee extension. It is important to begin muscle strengthening exercises to provide stability and support for the new knee. For the first 6 weeks, continuous passive motion is sometimes used depending on the patient and doctor. This is used to reduce swelling and increase range of motion. Usually, the CPM will be used for 4-6 hours a day while the patient is in bed. At the end of the 6 weeks, the patient should have achieved 0-110 degrees of knee range of motion. Patients will continue their exercise treatment during outpatient physical therapy. Around 3-6 weeks, patients can begin to walk with a cane or one crutch. After 6-8 weeks, patients who are not required to bend at their jobs may return to work. Increased activity will continue to increase muscle strength and range of motion. After 3 months, patients may begin light recreational activities. At this point, the patient should be able to walk over 1 mile with minimal pain and swelling. At 4-6 months, patients may begin to engage in more strenuous physical activities, and as long as there are no complications, patients should continue to progress until they have reached their maximum medical improvement. At this point, they should be relieved of their knee dysfunction and discomfort.
Managing Pain and Swelling
One of the biggest concerns for patients following total knee arthroplasty is how to manage pain arising both from the arthritic condition and from the surgery itself. In fact, the major reason why patients delay or decline having a knee replacement is the fear of pain and the perception that nothing can be done to relieve the pain. Patients are now able to rest assured that the management of pain following knee replacement can lead to a relatively pleasant experience if managed properly. Appropriate management of pain at all stages of knee replacement is essential to the overall well-being and satisfaction of the patient. Considering that ineffective pain management can result in decreased mobility, less desire to participate in therapy, prolonged recovery time, and a less favorable outcome. Pain management strategies for knee replacement can be separated into various stages including: pre-operative, peri-operative, and post-operative phases. A variety of medications exist to control pain following knee replacement. These may include: NSAIDs (non-steroidal anti-inflammatory drugs) such as ibuprofen, COX-2 inhibitors, simple analgesics such as acetaminophen, and more potent narcotic medications. Medications are often used in combination with other forms of pain management. Icing can help to minimize swelling and reduce pain. This can be accomplished using a variety of methods including ice packs or coolants, a frozen bag of vegetables, or modern icing units. Recent studies suggest that cryotherapy may be more effective than continuous passive motion machines in controlling pain and swelling. Elevation and rest are easy methods for pain management particularly in the early stages of recovery from knee replacement. It is suggested that the patient elevate the leg higher than the heart for 20-30 minutes at a time several times during the day in order to control pain and swelling.
Physical Therapy Exercises
Another potential treatment for increased function is physiotherapy using a continuous passive motion (CPM) machine. Although this is not an exercise, it can serve to aid the exercises that follow in its ability to increase flexion. CPM can be effective but its cost effectiveness in comparison to other forms of physiotherapy has been questioned in recent years.
Despite 12 weeks of supervised physical therapy, some patients continue to perform exercises afterwards. Patients with greater improvements are those who are active in their recovery. A home exercise program is guided by the supervised therapy and is performed 2-3 times a day. Exercises are maintenance-type exercises for overall leg strength and range of motion. Exercise level should be guided by swelling and pain levels with the low-impact, pain-free nature of aquatic exercise making it an exercise of choice. Combining aerobic conditioning with muscle training has also been shown to be a key factor for increased function. This may come in the form of a light walk, but care should be taken not to overdo it. With exercise intensity, the patient is guided by the response of the knee. Duration and frequency can be increased as and when the knee becomes stronger.
Physical therapy exercises are an important part of successful recovery after total knee replacement. Physical therapy is not used initially after surgery but when the surgeon allows. It is usually started 3-8 weeks after surgery, but the time frame is different for everyone and the recovery milestone of when to start physical therapy is when the patient can fully extend the knee and has adequate strength to lift the leg against gravity. Please consult the doctor before starting any exercise program. Before discussing specific exercises, it is important to understand how exercise can benefit the recovery process.
Returning to Normal Activities
Available evidence suggests that a program of strengthening, balance retraining, agility training, and sports-specific activities all help return patients to their previous level of activity or sport after TKA. Several authors have also suggested that postoperative rehabilitation should include the use of closed chain exercises. It is believed that closed chain exercises provide a more functional and global muscle activation. This form of exercise may be more beneficial in returning patients to a higher level of activity and sport. McClelland et al. (2007) developed and feasibility tested a sport-specific training program for patients post TKA. The six-week program included drills, skills, and endurance training for golf and lawn bowls. Although the numbers tested were small, the program did provide patients with enough confidence in their knee to return to these sports.
