Research And Evidence In Practice




Weakness and Strength.


Introduction to Critical Appraisal Assessment

Knee Osteoarthritis (OA) is found to be common chronic problem in adults which affects their muscle strength in quadriceps and hip areas with aging (Felson et al., 2000). One of the earliest sign of knee OA is muscles weakness of the quadriceps. The muscle weakness in these areas may cause disease consequential to agonising pain while standing or walking. Strengthening of muscles improves functionality of knees therefore, exercise is highly recommended to improve the condition (Zhang et al, 2008). In order to develop optimal strengthening programs, a detailed understanding of impact of knee OA on other muscles must be analysed. Studies suggests that weakness of hip muscles may be related to knee OA, but very less research has been conducted so far.

Aim and objective- The aim of this paper is to compare the hip muscle strength of people with knee OA with those without knee OA. The strength of the internal and external rotator, hip adductor, abductor, and flexor and extensor muscles will be tested for both groups. It was hypothesized that those who are suffering from knee OA would be having significantly weaker hip muscles as compare to those who do not have knee OA. The main findings of research indicates that the hypothesized statement is true, but with some limitations that will be discussed ahead.

Sample and Recruitment- To conduct the study, eighty-nine people with knee OA and twenty-three without OA of age below 50 years were recruited from a local community. Knee OA participants was having the disease at least in one knee. With pain score of three and above on the scale of eleven, the participants had met the American College of Rheumatology’s criteria (Altman, 1986). The participants of controls were free from any kind of hip, knee or lower back pain for at least a time span of six months and did not consume anti-inflammatory medication. The University of Melbourne Human Research Ethics Committee granted ethical approval. A written informed consent was provided to all participants.


The knee pain was measured on the scale of 0-11 (where 0 is no pain) using The American College of Rheumatology classification criteria. For participants with OA with bilateral eligible knee, the most symptomatic extremity was tested. For control participants, the study extremity was randomly selected. The strength of internal and external rotation, hip flexion, abduction, adduction and extension was measured. After familiarising participants with the procedure, the maximum effort test was performed in three trails of 5 seconds each with a difference of 15 seconds rest. The maximum force output was converted into torque by multiplying it by the resistance level arm, then standardised to demonstrate strength in relation to the body mass. The strength of hip flexion (external and internal rotation), adduction and abduction was measured by a hand-held dynamometer (HDD) in supine position. The HDD was placed on the superior pole of the patella of the participants while bending 90o. The hip extension was measure by a force transducer connected with and electronic inclinometer, while attached to the cuff of participants. The HDD is a quick and effective tool to measure knee strength. Roy & Doherty, 2004 assess the test reliability of HDD using standard protocols. The study revealed that the test reliability to measure knee extensor strength in case of hip fracture, is high while using standard protocol for HDD (Roy & Doherty, 2004).

The McMaster and the Western Ontario Universities Osteoarthritis Index were used to measure the self-reported knee pain and trouble in physical function of the OA group. The range of pain score was from 0-20 and physical function range from 0-68, where 0 is no pain or dysfunction. 

The statistic data was collected and analysed by the SPSS statistical software version16. To compare vivid characteristic between groups, independent chi-square and t-test were used. Univariate linear model, with age and sex as covariates, was used to compare potential influence of age and sex on the muscle strength. The SPSS statistic software is used for both qualitative and quantitative analysis. This is one of the most popular statistical software which is perform extremely complex data manipulation and analysis using simple instructions. However, there is one major limitation of SPSS, which is it cannot be used to analyse a very large set of data (Statistic Solution, 2020). In this research, although the number of participants was less, but is the same research has to be carry on a larger group of people for more accurate and detailed result, then this software may fail to accommodate and process the large clinical data. 

Weakness and Strength

Although the research involves the use of reliable research tools and criteria, there were some limitations. One such was, the control group was somewhat younger and comprised majorly if women as compare to OA group. The knee OA is found to be more prevalent in people aging above fifty years, although it can be found in people of age 20 or 30 years caused by joint injury or joint stress due to overuse (WebMD, 2020). The main reason behind osteoarthritis is stiffness of joint cartilage due to aging. Other reason are heredity, obesity, injury and joint overuse which may result into cartilage damage. If the control group includes people of age above 50 years, then the comparison would be more comprehensive and complex.

Another limitation of the research was the hip radiographs were not obtained. This excludes the probability of coexistence of hip OA in the knee OA group. However, the existence of hip OA in some or all of knee OA participants might affect the cause of the weakness of hip muscles, this is improbable as the participants had gone through the screening with respect to the hip pathology, in the same manner as the control group underwent.

Besides limitation, the outcome proved to be quite convincing and accurate. The study concluded with comparing hip muscle strength with suggestive knee OA and asymptomatic group. The researcher observed significant weakness of external and internal rotators, flexors, extensors, abductors and adductors in people with knee OA. The result favoured the hypothesis. Involvement of strength of hip muscles in preventing knee OA was found. The outcomes suggested the involvement of hip strengthening exercise into therapy procedure for knee OA.

The researchers suggest future research on the combination of quadriceps muscles strengthening and hip muscles strengthening for the treatment of knee OA. It is well known that quadriceps strengthening is a fundamental part of rehabilitation regimens for knee osteoporosis. Therefore, it is possible that the result of the exercise therapy can be optimised with the combination of strengthening both muscles.

References for Critical Appraisal Assessment

Altman, R., Asch, E., Bloch, D., Bole, G., Borenstein, D., Brandt, K., & Howell, D. (1986). Development of criteria for the classification and reporting of osteoarthritis: classification of osteoarthritis of the knee. Arthritis & Rheumatism: Official Journal of the American College of Rheumatology29(8), 1039-1049.

Felson, D. T., Lawrence, R. C., Dieppe, P. A., Hirsch, R., Helmick, C. G., Jordan, J. M., ... & Sowers, M. (2000). Osteoarthritis: new insights. Part 1: the disease and its risk factors. Annals of internal medicine133(8), 635-646.

Roy, M. A. G., & Doherty, T. J. (2004). Reliability of hand-held dynamometry in assessment of knee extensor strength after hip fracture. American journal of physical medicine & rehabilitation83(11), 813-818.

SPSS Statistics Help. (2020). Statistics Solutions. Retrieved from

The basics of osteoarthritis. (2020). WebMD. Retrieved from

Zhang, W., Moskowitz, R. W., Nuki, G., Abramson, S., Altman, R. D., Arden, N., & Dougados, M. (2008). OARSI recommendations for the management of hip and knee osteoarthritis, Part II: OARSI evidence-based, expert consensus guidelines. Osteoarthritis and cartilage16(2), 137-162.

Remember, at the center of any academic work, lies clarity and evidence. Should you need further assistance, do look up to our Nursing Assignment Help

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