RELATIONSHIP OF MUSCLE STRENGTH AND ‘Q’ ANGLE IN KNEE OSTEOARTHRITIS : S. G. Sudhan * MS Indira **

Abstract :
The knee is the most common weight bearing joint affected by osteoarthritis (OA), with the disease predominantly affecting the medial compartment of the tibio femoral joint. Muscle weakness is common in individuals with knee osteoarthritis and has been suggested to contribute to abnormal knee joint mechanics. The study focuses on gluteus medius and quadriceps muscle strength on q angle variations of osteoarthritis knee. The observational study was done with 50 OAknee subjects, over a period of one month at Physiotherapy department of Vels University. The subjects were assessed of their muscle strength using MRC grading and Q angle determined by surface markings. The results indicate that the ‘t’tests shows statistically significant reduction in gluteus medius and quadriceps muscle strength with p<0.01 and cause increase in Q angle with p <0.01. hence there is a positive relationship between muscle strength and Q angle of OAknee.
Keywords : osteoarthritis, gluteus medius, quadriceps, Q angle

Introduction
Osteoarthritis is also known as a degenerative joint disease. The knee is the most common weight bearing joint affected by osteoarthritis, with the disease predominantly affecting the medial compartment of the tibial femoral joint. The main factor associated with osteoarthritis is an abnormal increase in the mechanical stress in the some part of the articulating surface .It occurs most commonly from the group of above 50 year, above 80%of the 65%and above population in the country suffers with wear and tear. In which 40%of people suffers with osteoarthritis. Those with osteoarthritis knee have 25%to 45%loss of knee extension strength and 19%to 25%loss of knee flexion strength.
It is also felt that proximal joint muscle weakness could influence this process. Tibial torsion is the angle formed between transmalleolli axis and transverse axis of the knee joint. Abnormal torsion has an impact on the ankle and knee biomechanics during gait, thus affecting external loading of the knee joint, which in turn lead to osteoarthritis. Excessive internal tibial torsion may contribute to an internal foot progression angle and has been associated with medial compartment degenerative arthritis of the knee in the adult.
The q angle of the knee is a measurement of the angle between the quadriceps muscle and Patella tendon and it provides useful information above the alignment of the knee joint. It is likely to influenced by the muscle strength of varying group of muscles that alter the mechanics of knee other that Quadriceps alone. Gluteus Medius weakness is very common among people above age 50 and more evident with obesity indicating the mechanics change in the knee joint too. Thus this study aims to establish the level of weakness of Gluteus medius and Quadriceps influencing on Q angle of OA knee.

Methodology:
The observational study done over a period of 4 months , with a sample of 50 OA knee subjects was carried out at Physiotherapy department of SOPT, Vels University after obtaining ethical clearance. Informed consent was obtained and subjects were included based on the inclusion criteria of females aged above 40 years diagnosed with unilateral OA knee. Subjects with rheumatism, recent injury to hip, knee, ankle and foot of the involved side, deformities, knee joint surgery, and neurological involvement were all excluded.
All the measurements were taken by a blinded assesse for both the affected and unaffected sides. The subjects muscle strength was measured in standard test positions using MRC grading of Kendall. The Q angle was measured with long arm goinometer using surface markings and recorded. The standing position was adopted to get the recordings on loaded knee and as is best recommended position.
The data was recorded and statistically analysed using’t’- test for the two –sample assuming unequal variances comparing affected and unaffected leg measures.

Table 1: comparing the data of gluteus medius strength on affected and unaffected side indicating significant change in unaffected knee.

Table 2: comparing the data of Quadriceps muscle strength on affected and unaffected side indicating significant change in unaffected knee.

 

 

Figure 1: The comparison of data between affected and unaffected knee

Discussion
The study has been aimed to compare the gluteus medius, quadriceps muscle strength and Q angle variation of osteoarthritis knee. The gluteus medius was weak compared to the normal side could further detoriate the mechanics of the knee. The weakness of gluteus medius can be attributed to the gender and obesity. The quadriceps weakness could be vice versa with directly proportional to the osteoarthritis.
Decreased muscle strength has repeatedly been reported in arthritis patient. The present study has also recorded the similar finding .the studies of healthy subject have reported relationships between muscle strength and functional status. Furthermore an association between muscle strength and risk of recurrent falls. Obviously muscle strength and endurance translates into good functional capacity and lessened disability .that is one of the reasons why muscle strength is linearly and negatively correlated with disability in patient with osteoarthritis.
The q angles have shown to be increased in the OA knee, possibly as the degeneration progresses and more pain and immobility could be aggravating factors.
Conclusion: There is positive relationship between muscle strength, Q angle and Osteoarthritis knee and negative relation between muscle strength OAknee.

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