Diagnostic process of knee OA The main purpose of the diagnostic process is to rule in or rule out a diagnosis of knee OA. The correct diagnosis is important in determining the appropriate treatment. The components of diagnosing a patient with knee OA include the patient history, physical examination, imaging studies, and in some cases laboratory testing (Michael et al., 2010). Patient history Patients with knee OA often complain of pain with movement, which typically occurs when movement begins or when the patient begins to walk (Michael et al., 2010). The pain is often described a dull ache. As the disease progresses, the patient will report that the pain is more continuous than intermittent. Pain begins at rest or at night, which is a sign of advanced OA. It is important to ask patients what their functional activity status is and how the knee pain affects their daily life. Often patients with knee OA will progress to some type of disability because of difficulty with walking, managing stairs, and standing. Patients may see a functional decline as the disease progresses. It may also be useful to get a job history or recreational history to help get a complete picture of the patient’s history. Specific historical features of OA: Pain: ● Pain at the beginning of movement. ● Pain during movement. ● Progression of pain to permanent pain or night pain. ● Need for pain medication. Loss of function ● Stiffness. ● Limitations in range of motion. Staging The clinical signs and symptoms of OA and the radiographic findings follow a typical course with progression of the disease and can be incorporated into a clinical staging system. A number of scoring systems have been developed. One scoring system is after Kellgren and Lawrence, 1957, that still stands today: ● Stage 0 : No abnormality. ● Stage 1 : Incipient osteoarthritis; beginning of osteophyte formation on eminences. Functional decline among those with knee OA According to Cross and colleagues (2014), OA ranks as the 11th highest contributor to global disability and is the leading cause of functional limitation in older adults. Functional limitations among individuals with knee OA include difficulty with walking and managing stairs. Arthritis-related conditions have been found to be the second most common reason for medical visits related to chronic conditions and are only second to hypertension (Cherry et al., 2008). Interventions provided to individuals with knee OA are performed to restore function for patients who are nonsurgical and those patients who present postoperative following a total knee replacement. It is important for the physical therapist to recognize and understand patterns of functional decline to effectively treat functional limitations in patients with knee OA. A study was performed to describe trajectories of functional decline among initially well-functioning people with or at risk of developing knee OA and to examine the association of demographic, disease severity, and modifiable risk factors with trajectories (Cross et al., 2014). This study found that the severity of radiographic knee OA and knee pain and the presence of obesity and depressive symptoms at baseline were associated with decline (Cross et al.). There was no apparent association observed for age, sex, or race with the trajectory groups (Cross et al.). These findings can help to identify those patients at greater risk of knee OA and those at risk for developing functional limitations. The findings of this study are
● Limitations of daily activities. ● Need for assistive devices/aids. Other symptoms ● Joint crepitation. ● Elevated sensitivity to damp/cold. ● Stepwise progression (Adapted from Michael et. al, 2010). Physical examination The physical examination includes inspection, palpation, testing of the range of motion, and special testing as needed. Special function tests may include ligament stability, meniscus tests, and gait analysis. Ligamentous testing may include testing of the lateral ligaments with valgus or varus stress and testing the anterior and posterior cruciate ligaments with drawer tests (Michael et al., 2010). The menisci should be tested manually. The femoropatellar joint and patellar mobility should be evaluated to look for signs of irritation as a result of any damage or dysfunction of these structures (Michael et al.). Imaging studies X-ray imaging studies are used for primary diagnosis of knee OA and to assess the progression of the disease (Michael et al., 2010). An X ray that shows the narrowing of the joint space is a good indicator of knee OA as well as bone spurs (Bhatia et al., 2012). In some cases, to gain further clarity, an MRI scan may be needed (Bhatia et al.). An MRI will allow the physician to see if there is any damage to the soft tissue structures in the knee joint (Bhatia et al.). Laboratory testing may also be included in the diagnostics, which can help rule in or out other conditions that may be contributing to knee pain. ● Stage 2 : Moderate joint space narrowing; moderate subchondral sclerosis. ● Stage 3 : > 50% joint space narrowing; rounded femoral condyle; extensive subchondral sclerosis; extensive osteophyte formation. ● Stage 4 : Joint destruction; obliterated joint space; subchondral cysts in the tibial head and femoral condyle; subluxed position. consistent with the risk factor of obesity for developing OA or for experiencing a steady progression of the disease. Obesity puts a person at greater risk of developing OA and can enhance the progression of the disease, which is why it was likely found to be more associated with greater functional decline. Excess weight Increased weight can have a negative impact on joint integrity and is a risk factor for the development of knee OA. Weight reduction is one way to reduce knee OA and limit the progression of the disease. Nielsen and colleagues (2017) reported that out of the risk factors for knee OA – obesity, previous knee injury, and family history of OA – obesity is believed to be the most important among the three. “Studies of OA have constantly shown that overweight people have higher rates of knee OA than nonoverweight control subjects” (Bhatia et al., 2012). In one systematic review, researchers found that the onset of OA knee pain in individuals who were over the age of 50 was related to excess weight or obesity in 25% of cases; only 5% were caused by previous knee injury (Silverwood et al., 2015) The force across the knees is three to six times a person’s body weight, which means that people who have more mass cause extreme forces on their knees. The increase in force on the knee joint can lead to the early onset or steady progression of knee OA (Bhatia et al., 2012).
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