Analysis On The Sports Biomechanics And Electrophysiological Characteristics Of Lower Limbs In Patients With Patellofemoral Pain Syndrome

Objective:To investigate the differences in hip and knee sports biomechanics and muscle electrophysiology between people with and without patellofemoral pain syndrome(PFPS),to clarify the changes of lower limb characteristics that may be caused by patellofemoral pain syndrome,and to provide theoretical guidance for the clinical formulation of rehabilitation program.Method:Included 26 subjects who met the criteria were divided into PFPS group(13 patients with PFPS)and control group(13 healthy subjects).Both subjects underwent an isokinetic muscle strength test,response latency test and jump-landing test.The relative peak torque(PT)of concentric knee flexors and extensors,hamstrings and quadriceps ratio(H/Q),relative peak torque of concentric abductors and adductors ratio(Abd/Add)were obtained for the two groups at 60°/s,120°/s and 180°/s angular velocities.The electromechanical delay of the vastus medialis obliquus(VMO),vastus lateralis(VL),biceps femoris(FB),gluteus medius(GM)and adductor longus(AL)was obtained during the response latency test.The normalized root mean square(RMS)of VMO,VL,BF,GM,AL and VMO/VL ratio were obtained in the jump-landing test,as well as the minimal knee flexion angle and maximum hip adduction angle in the jumping and landing stages.The difference between the above indexes was compared after the two groups completed the test.Results:In the isokinetic muscle strength test,the relative peak torque of knee extensors in the PFPS group(0.98±0.31)was different from that in the control group(1.57±0.54)at 120°/s(P<0.05),it(1.08±0.35)was also significantly different from that in the control group(1.45±0.44)at 180°/s(P<0.01).And the hamstring/quadriceps ratio of the knee joint in the PFPS group(100.69±26.31,103.92±35.25)was different from that in the control group(80.38±20.59,79.92±19.38)at 120°/s and 180°/s(P<0.05).The abductor/adduction ratio of the hip joint at 120°/s and 180°/s(60.50±13.89,81.46±53.88)was different from the control group(49.97±10.77,41.08±12.33)(P<0.05).In the response latency test,only the EMD of VMO in the PFPS group(74.64±9.48)was significantly different from that in the control group(64.23±8.86)(P<0.01).In the jump-landing test,the differences of normalized RMS of VMO and VL between PFPS group(1.28±0.63,3.78±1.51)and control group(2.07±1.00,2.34±1.50)were statistically significant(P<0.05).The normalized RMS of VL was significantly higher than VMO in the PFPS group(P<0.01),and VMO/VL ratio in the PFPS group(0.35±0.13)was significantly lower than that in the control group(1.04±0.44)(P<0.01).In the PFPS group,the minimum knee flexion angle(94.00±12.05)and maximum hip adduction angle(47.43±4.50)in the jumping stage were not different from the control group(91.27±10.65,47.57±7.51)(P>0.05),and the minimum knee flexion angle(105.72±6.44)and maximum hip adduction angle(30.46±4.93)in the landing stage were not different from the control group(103.43±6.86,33.79±4.94)as well(P>0.05).Conclusion:(1)The muscle strength of the knee extensors decreased in the PFPS patients with moderate and rapid isokinetic velocity.With the increase of the speed,the muscle strength of the knee flexors and extensors gradually showed unbalanced state.(2)The EMD of VMO in PFPS patients was prolonged,suggesting that PFPS may be related to the nerve control function of the muscle.(3)VMO electrical activity in PFPS patients was weakened and VL electrical activity was enhanced,indicating an imbalance between VMO and VL.