modalities to reduce pain. A patient who has minimal functional deficits, but a varus thrust and medial knee pain when walking, may have symptomatic improvement from gait retraining. Falls are more common in patients with knee OA than in older adults without lower extremity pathology. These falls can have serious health consequences, including trauma and fracture, which can reduce quality of life and increase the risk of mortality for older adults. To date, there are limited prospective and high- level studies on balance retraining alone for patients with knee OA. However, a recent systematic review found that strength training, Tai Chi, and aerobic exercises improved balance scores for patients with knee OA (Mat, Tan, Kamaruzzaman, & Ng, 2015). A recent pilot randomized controlled trial evaluated the effect of a 10-week balance training program on pain, functional outcomes, and balance (Takacs, Krowchuk, Garland, Carpenter, & Hunt, 2017). This program consisted of home and partially- supervised balance classes that were performed four times per week. Although patients in the program demonstrated improvements in pain, function, and fear of movement by the end of the intervention, there was no change in the Community Balance and Mobility scale, which is a performance-based test of balance. Therefore, while balance may be an important target for patients with knee OA, it is likely that balance retraining should be combined with other forms of exercise therapy, including strengthening, Tai Chi, or aerobic exercises to achieve maximum benefit, improve balance scores, and reduce the risk of falling. Gait retraining has been proposed as a mechanism to delay the progression of OA by normalizing movement patterns and reducing the external knee adduction moment. Reducing the adduction moment can be achieved by either changing the position of the knee and moving it more medially when walking, changing the orientation of the ground reaction force vector to a more lateral position (as shown in Figure 3), or moving the center or pressure to a more lateral position at the foot-ground interface. A study by Barrios et al. found that it was possible to reduce the external knee adduction moment in individuals who had varus knee joints (Barrios, Crossley, & Davis, 2010). This was done by providing training sessions in a motion analysis laboratory with feedback of the knee adduction angle. Subjects were given instructions to “bring your knees
closer together” when walking to reduce the varus angle. A more recent study found that decreasing the toe-out angle when walking changed the knee position and reduced the adduction moment. Subjects with knee OA who completed a 6-week course of walking with a toe-in gait pattern had reduced pain at the end of the intervention (Shull et al., 2013). A recent systematic review concluded that gait retraining interventions for patients with knee OA were not only able to reduce the external knee adduction moment, but also reduced pain and increased function (Richards, van den Noort, Dekker, & Harlaar, 2017). The same study also concluded that implicit rather than explicit instructions were most beneficial at reducing the adduction moment. This means that providing more general instructions to reduce the knee adduction moment may be more beneficial than providing rigid and specific instructions. While there may be benefits to these retraining protocols on movement patterns and function, they may not be appropriate for all patients. Normal walking is a relatively unconscious activity that does not require a large amount of focus. Walking patterns are inherently variable between individuals and are likely “tuned” to each person’s alignment, body size, and other physiological properties. In most cases, an individual’s self-selected walking pattern is metabolically efficient for that person. When an individual’s normal walking pattern is disrupted or altered with movement retraining, it also may increase the metabolic demand, muscle coordination strategies, and difficulty with ambulation. A recent study found that when healthy individuals without lower extremity impairment adopted gait- retraining strategies normally performed for patients with knee OA, there was an increase in the metabolic energy expenditure and cognitive load (Caldwell, Laubach, & Barrios, 2013). Gait patterns to reduce the adduction moment, such as increasing trunk sway or walking with a toe-in gait pattern, may make an individual less stable when walking. Because altering gait patterns may increase metabolic cost of walking and alter normal kinematics, gait retraining interventions may not be appropriate for patients with poor balance, low levels of endurance, and difficulty with cognitive processing. These factors should be weighed against the potential benefit of these interventions on a patient-by-patient basis.
OTHER CONSERVATIVE TREATMENTS FOR KNEE OA
In the most recent clinical practice guidelines put forth by the American Academy of Orthopaedic Surgeons (AAOS), there was a strong recommendation for several conservative treatments for patients with knee OA. In particular, several studies supported the recommendation that patients with knee OA participate in self-management programs, strengthening, low-impact aerobic exercise, and neuromuscular education (Jevsevar et al., 2013). In the description of this recommendation, it was stated that Weight loss In the same set of clinical practice guidelines from the AAOS, there was a moderate recommendation in support of weight loss programs for individuals with knee OA. In a recent large diet and exercise study, investigators found several clinically important outcomes for individuals with knee OA who lose weight (Messier et al., 2013). This study of 399 participants found that diet and exercise or diet alone produced a meaningful loss of body weight in individuals with knee OA. Patients in the weight loss groups also demonstrated functional improvement by the end of the study. Those who were in the diet and exercise group had the largest reduction in joint pain. In individuals who lost weight, there was also a reduction in systemic inflammatory biomarkers, as well as a reduction in joint loads in the knee. These are important factors that not only may help to improve physical function, but also may help to slow the progression of knee OA. However, it should be pointed out that an 18-month follow-up analysis from the same study showed that there was no difference in the structural changes in the knee joint between those who did and did not lose weight in the previous study
the exercise interventions were most commonly performed under the supervision of a physical therapist. Other programs, such as the self-management programs and aerobic walking programs, were carried out by physical therapists or other health professionals. Most of these interventions are described in the previous section, but additional conservative options of which a physical therapist or physical therapist assistant should be aware are described next. (Hunter et al., 2015). Eighteen months may be too early to see these changes occurring, or perhaps weight loss alone is not enough to stop the progression of OA. The lack of differences in structural changes highlights the fact that symptoms do not always correlate with radiographic evidence of OA. Although weight loss may not stop the structural progression of the disease, the evidence shows that weight loss can improve functional outcomes in patients with knee OA. There is a significant and strong dose-response relationship between the amount of weight lost and the amount of functional improvement. The more weight that a person can lose, the greater the functional improvement will be (Atukorala et al., 2016). The results from studies on weight loss suggest that dietary changes and physical exercise should be included in a comprehensive intervention for patients with knee OA. While evaluating dietary needs may be outside the scope of care for physical therapists, referrals to dieticians should be considered for appropriate patients.
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