Quantitative Assessment of Muscle Activity and Joint Load in Braced and Unbraced Osteoarthritis Knee by External Strain Gauge Sensor.

OBJECTIVES

Altered biomechanics leads to the development of degenerative joint disease. The joint pressure and dynamic loading varies during activities of daily living. The study was undertaken to assess the muscle activation pattern of the medial and lateral knee compartments (tibiofemoral joint) during gait in osteoarthritis subjects without and with knee brace undergoing either exercise therapy or balance therapy. The joint load was assessed by the strain gauge transducer and the weight shift pattern is taken as an indicator for the muscle activation pattern.

METHODS

In a prospective design study on 57 male subjects diagnosed osteoarthritis knee with Kellagren-Lawrennce scale walked barefooted with and without designed offloader knee brace on a level surface for three minutes. The subjects were allocated in two different study groups i.e. Conventional (exercise therapy) (Control Group, n=31) and Structured Neuromuscular Postural Training (SNPT) group (Balance therapy) (Study Group, n=26). The subjects were sub grouped as pre-elderly (40-60 Years) and elderly (>61 years) group in both. The quantitative assessment of muscle activity and joint loading with and without knee brace was done using designed strain gauge sensor instrument. The pressure changes of strain gauges of muscles around the knee joint viz. vastus medialis (VM), vastus lateralis (VL), semi membranosus/tendinosus (Medial Hamstring) (MH), Biceps Femoris (Lateral Hamstring) (LH), gastro-soleus (GS) and tibialis anterior (TA) muscles during normal gait were observed at baseline and 6 weeks follow up after undergoing exercise therapy or balance therapy treatment as per allocation of study groups. The digital values from MATLAB were recorded and analyzed.

RESULTS

At the end of 6 weeks conventional/SNPT (structured neuromuscular postural training) treatments, medial hamstring muscle activity showed significant difference (p<0.001) in pre-elderly subgroup, while significant difference was seen in vastus laterals (VL), medial hamstring (MH) (p<0.005) and lateral hamstring (LH) muscles (p<0.001) in elderly subgroup. Further, the muscle co-contraction has been higher for vastus medialis-medial hamstring (VM-MH) pair compared to vastus lateralis-lateral hamstring (VL-LH) pair without brace at baseline. The application of offloader valgus knee brace significantly increases VL-LH co-contractions in magnitude and decreases in VM-MH co-contractions at 6 weeks follow up.

CONCLUSION

Muscle activity increased in medial hamstring both in pre-elderly and elderly subjects. While, Vastus Laterals and lateral hamstring showed increased activities in elderly subjects. Hence, balance training and the application of off loader knee brace will be helpful to redistribute the load on medial tibiofemoral compartment.