PT Critically Appraised Topics

Document Type

Critically Appraised Topic

Publication Date


Clinical Scenario

The patient who indirectly led me to pursue this question was a 62 year-old male with a diagnosis of cauda equina syndrome secondary to excess inflammation after a lumbar spine decompression surgery. Medical treatment to date has included nine months of aquatic and land-based physical therapy. Problems identified include weak and insensate bilateral lower extremities, notably weak hip and knee extensors, plantarflexors, dorsiflexors and hip abductors. This patient led me to seek out the efficacy of aquatic therapy, however the research is lacking in studies concerning cauda equina syndrome and aquatic therapy, as the condition is rare. As this clinic has the only pool in town, and many patients are referred here specifically for aquatic treatment, I was interested in what the research has to say about aquatic therapy. Knee osteoarthritis(OA) was the most commonly occurring diagnosis with randomized control trials, so I decided to seek out what the literature reports for such patients.

Clinical Question

Is aquatic therapy more effective than land-based exercises at affecting the pain, strength and mobility deficits associated with knee osteoarthritis?

Clinical Bottom Line

Based on the results of the outcomes from Lund et al. (6) and Wang et al. (13) aquatic therapy has not been shown to be more or less effective than land-based exercises at affecting the pain, strength and mobility deficits in patients with primary knee OA. Overall, these two high-quality studies provided limited evidence to suggest that either type of therapy may be beneficial compared to a control group receiving no additional exercise training. The evidence is limited due to inconsistent results and small amounts of significant differences between groups.

Three months after treatment completion, Lund et al. reported a small decrease in knee flexor and extensor strength between the aquatic and control groups, a small decrease in resting pain level between the land-based and control groups and a small increase in knee flexor and extensor strength between the land-based and control groups. The study by Lund et al. also reported fewer subjects than desired to achieve an adequate power attributed to results. This was the only major threat to internal validity between the studies. Immediately after treatment completion, Wang et al. reported that KOOS ADL scores, 6MWT distances and knee extension measurements for both exercising groups were significantly different and improved compared to the control group. Although pain level was not shown to be statistically different from the control group, a clinically significant decrease in pain level was demonstrated within both exercise groups. Despite limited significance, these contradicting results suggest that if either therapy is effective at addressing impairments associated with knee OA, they are likely similarly effective compared to no therapy. As it has been shown that exercise has a wide range of benefits for patients with knee OA, these studies may suggest, or at least not deny, an encouraged use of aquatic therapy for appropriate patients, if available, to compliment land-based exercises.

Results are difficult to generalize to the population due to the amount of exclusionary criteria for subjects allowed into these studies. Most patients have more complicated medical histories or have tried previous treatment. Furthermore, the subjects in the study by Wang et al. were community dwelling adults being treated in exercise class situations. As they likely represent the greater population, their functional level is also likely higher than a majority of patients seen in clinics. While the clinical effectiveness of an aquatic or land-based exercise class for addressing pain, function and knee extension for patients with knee OA is not clear, the financial and time costs of treatment appear to be consistent with methods commonly available and the protocols employed would be readily applied in a clinical setting.

The literature is not lacking high-quality randomized controlled studies (RCTs) on this topic; however the methods employed are consistently inconsistent. Further research is necessary to adequately answer this clinical question, specifically more controlled studies to address the length and timeframe of a successful program, the type of exercises, increased power of the statistics with more subjects, and more studies with control groups to minimize outside factors from skewing results.