Knee Osteoarthritis (OA) is the degenerative disease of the articular cartilage of the knee leading to bone on bone irritation that causes symptoms such as inflammation, swelling, stiffness and pain. (David Dugdale, 2014). The knee is a common place for OA to occur as it is a weight bearing joint on the end of two long levers and is often exposed to shear force through daily activity such as walking and squatting.
Exercise-based rehabilitation programs have long been considered the cornerstone in conservative management of knee OA and have been praised for their ability to reduce inflammation, address factors that predispose a patient to knee OA and improve overall health status. (Page, Hinman & Bennell, p. 145, 2011). Predisposing factors addressed in exercise programs include being overweight, having a history of repetitive joint use such as an athlete, having a previous knee injury and having poor alignment of the knee such as a valgus or varus positioning. (Fernandes, p. 1125, 2015). Current protocol includes strengthening and aerobic exercise individualized to the patient along with education on lifestyle and promotion of a healthy exercise regime, diet and pacing initiative for everyday activities. (Page, Hinmann & Bennell, p. 146, 2011).
Meta-analyses and systematic reviews have provided the evidence-based foundation of knee OA exercise protocols adopted today, however, reviewing these findings and implementing the most recent knowledge is imperative in improving the health and wellbeing of each individual sufferer of knee OA. For the critical analysis of the current literature on knee OA exercise programs, databases searched included Cochrane Libraries, EBSCO, PubMed and Google Scholar. Systematic reviews of exercise programs were analysed and articles inclusive of knee OA and exercise-based therapy were hand selected for review. Many studies have focussed on knee OA as it is the most common form of OA. In collection of recent systematic reviews and meta-analysis, the amount of exemplary studies supporting land-based knee OA exercises, specific muscle strengthening exercises, proprioceptive activities with stress on specifying a program to an individual’s own body imbalance is clearly signified.
Bennell & Hinman (p. 6, 2011) collate the current evidence for exercise base therapy as being the most effective component in conservative management of knee OA. The main benefits cited from exercise therapy in knee OA include pain reduction, physical function improvement and optimised participation in social, domestic, occupational and recreational pursuits. (Bennell & Hinman, p.7, 2011). Muscle strengthening has been quoted in the literature as a key component to addressing pain, loss of function and range of motion in knee OA. Land-based exercise was been consistently shown in the literature to decrease pain and increase physical function. (Frasen & McConnell, p. 1, 2009). In this, it was also stated that increased supervision or group-classes of land-based exercise correlated with overall efficacy. (Frasen & McConnell, p.2, 2009). Supervision significantly improved results across a range of specific muscle strengthening exercises, those varying from simple quadriceps muscle strengthening programs to truncal muscle strengthening, balance co-ordination and lower limb strength training. (Bennell & Hinman, p.7, 2011). Clinical trials of strengthening exercise have spanned isometric, isotonic, isokinetic, concentric, concentric/eccentric and dynamic modalities. (Bennell & Hinman, p.8, 2011). Specific muscle strengthening exercise has been shown to improves strength, pain and physical function through creating muscle balance that in turn assists co-ordination and normalises motions. (Bennell & Hinman, p.8, 2011). In conjunction with this, aerobic fitness is also highlighted as important in increasing activity level. A recent randomised control trial found that knee OA test subjects undertaking a warm up exercise consisting of 10 minutes on an ergonomic reclined bike at moderate intensity compared to a control group without showed significant improvement in pain reduction and overall opinion on level of disability from knee OA. (Henriksen, Klokker, Graven-Nielson, Bartholdy, Schjodt, Jorgenson, Bandak, Danneskiold-samsoe, Christenson & Bliddal, 2014). In accounting for aerobic exercise, 12 trials reviewed revealed land-based exercise on reclining bikes or incremental walking produced reduced joint tenderness, increased respiratory capacity and function status. (Bennell & Hinman, p.8, 2011).
In the case of aquatic aerobic exercise and strength based training, little robust and valid evidence from clinical trials supports its efficacy when compared to the immense positive results seen in land-based exercise. It is however implicated as an effective modality for initial use in strength and aerobic exercise as studies show it is beneficial in reducing exercise induced joint pain. (Hinman, Nicolson, Dobson & Bennell, 2015). Another review that collated 40 random control trials found evidence that supports this finding, stating non-weight bearing exercise both aerobically and strength targeted has shown better results in reducing pain in the short term or initial stages of knee OA rehabilitation. (Tanaka, Oszawa, Kito & Moriyama, 2015). The findings of this systematic review also stated that weight-bearing exercise with our without muscle strengthening is effective in reducing pain. (Tanaka et al,. 2015).
Despite surmounting evidence of individual benefits of each type of exercise, there is still no clear indication over what exercise is the gold standard treatment for knee OA. It is suggested that reviewing a patient as an individual is the best way of prescribing a specific exercise program. (Bennell & Hinman, 2011). This involved examining the patients physical form, as well as taking into account their level of motivation and access to equipment, for example, evidence in hydrotherapy is limited because many patients are unwilling to commit financially, are fearful of water or don’t have the means to access facilities. (Bennell & Hinmann, 2011).
In review of the aforementioned exercise modalities and prescription considerations, a general outline for exercise prescription from clinical evidence of the current literature can be seen in appendix 1.
These principles are mirrored in the current EULAR (The European League Against Rheumatism) and extended upon in a more exhaustive protocol that draws upon lifestyle factors that influence knee OA and its disabling features. This includes an element of activity pacing, education on diet and exercise, use of appropriate footwear and the implications for use of assistive technology such as walking aids and grip apparatus’. (Fernandes et al, 2015). The EULAR protocol can be seen in appendix 2.
In reviewing the current literature of efficacy of exercise prescription for rehabilitation and pain management specific to knee OA it has been established that there is a vast array of encouraging clinical evidence. The findings of many Cochrane reviewed RCT’s suggests the validity of these findings are significant, whilst numerous peer-reviewed journals solidify this clinical knowledge. From this evidence, exercise therapy is acknowledged and solidified as a key pillar in the conservative management of knee OA.