The Effect Of Vastus Medialis Oblique/Vastus Lateralis Strength Imbalance In Pathogenesis Of Patellar Tendinopathy

PartⅠSurface Electromyographic Study of the Quadriceps in Athletes withand without Patellar Tendinopathy during Isokinetic ExerciseObjectives: To investigate the relationship between the imbalance between vastus medialis oblique and vastus lateralis and the occurrence of patellar tendinopathy.Subjects and Methods: A controlled laboratory study was done in forty knees of thirty-two athletes (Group A, twenty knees of sixteen cases without PT; Gourp B, twenty knees of sixteen cases with PT). All cases were examined by the isokinetic testing (60deg/s) and the surface electromyogram (sEMG) testing. The sEMG data of vastus medialis oblique (VMO) and vastus lateralis (VL) were dealed with Myoresearch XP1．03．06 (Noraxon, 2003) . Integrated electromyogram (IEMG) ratio of VMO and VL (VMO: VL)and on-set timing difference between two muscles (Time_VL-Time_VMO) in two groups were compared.Results: VMO: VL ratio was greater in PT group than that in control group. There was no difference between two groups in on-set timing difference.Conclusion: The athletes with PT had relative strength reinforcement in VMO, but no difference was found in the sequence of muscle activation comparing with the asymptomatic players.PartⅡThe MRI Study of Patellofemoral Alignment in Athletes withPatellar TendinopathyObjective: To evaluate the patellofemoral alignment in athletes with patellar tendinopathy.Subjects and Methods: Thirty-six atheletes (60 knees) were investigated in this study, Twenty-one atheletes with patellar tendinopathy (30 knees) and fifteen asymptomatic athletes (30 knees). Subjects were examined with bilateral knees (asymptomatic athletes) or involved knees (atheletes with patellar tendinopathy) by MRI. Axial images of the patellofemoral joint were obtained as subjects with their knees 0°flexion during non-weight-bearing and weight-bearing (15% body weight resistance) conditions. Measurements of patellofemoral alignment were obtained in mid-patellar images. Four indexs were used: 1) sulcus angle; 2) congruence angle; 3) patellar tilt angle; 4) lateral patellar displacement.Results: Compared to non-weight-bearing condition, both asymptomatic group and patellar tendinopathy group had less congruence angle(P<0．05) , less patellar tilt angle (P＜0．05) and greater lateral patellar displacement (P＜0．05) . Compared to the control group, no differences in each index were observed in patellar tendinopathy group during non-weight-bearing condition (P>0．05) , but during weight-bearing condition, both lateral patellar displacement and it's difference between weight-bearing condition and non-weight-bearing condition were significantly less in patellar tendinopathy group(P＜0．05) .Conclusion: Atheletes with patellar tendinopathy had less lateral patellar displacement during weight-bearing condition. It suggested there was patellofemoral malalignment in athletes with patellar tendinopathy.PartⅢThe Effect of Vastus Medialis Oblique/Vastus Lateralis StrengthImbalance on The Stress of Patellar Tendon Proximal Insertion--ThreeDimension Finite Element AnalysisObjectives: To develop a three dimension finite element model of the human knee joint using MRI images, and to evaluate how the stress of the patellar tendon proximal medial/lateral insertion change during vastus medialis oblique/vastus lateralis strength imbalance.Materials and Methods:1) A volunteer accepted MRI scan with his knee 60°flexion. The MRI images were used to reconstruct a three dimension model by Mimics 8．1．After optimized by Magic RP, the model was tetrahedron meshed by MSC. PATRAN. Patellar tendon was simulated, and material attribute was selected; 2) At the base of this model, we calculated the Von Mises stress of the patellar tendon proximal medial/lateral insertion during the load of vastus medialis oblique was increased from ON to 33N, 66N and 100N.Results: 1) A three dimension finite element model of the human knee joint, which including bone and cartilage was reconstructed. This model can reflect the real geometry structures of knee joint; 2) When the load on vastus medialis oblique was increased from ON to 100N, the stress of medial patellar tendon decreased, the stress of medial patellar tendon increased, the maximal stress of the patellar tendon proximal medial insertion decreased from 2．41 Mpa to 1．41 Mpa, and the maximal stress of the patellar tendon proximal lateral insertion increased from 2．90 Mpa to 5．03 Mpa.Conclusion:1) At the base of MRI images, we can reconstructed a three dimension finite element model of the human knee joint, which included bone and cartilage and reflected the real geometry structures of knee joint; 2) With the knee 60°flexion, when the load on vastus medialis oblique was increased, the maximal stress of the patellar tendon proximal lateral insertion increased, and that of the patellar tendon medial proximal insertion decreased. PartⅣThe Effect of Vastus Medialis Oblique/Vastus Lateralis StrengthImbalance on The Stress of Patellar Tendon Proximal Insertion--Experimental Biomechanical StudyObjectives: To evaluate the effects of varying vastus medialis oblique strength on tensile stress of medial/lateral patellar tendon proximal insertion, and to evaluate the validity of the three-dimensional finite element model of knee.Materials and Methods: Six fresh-frozen knee joint were collected and designed to fit models. With the knee 0°, 30°,60°flexion, the load of vastus medialis oblique increased from 0N to 30N, 60N, 100N. The tensile strain of medial/lateral patellar tendon was measured. After that, medial/lateral patellar tendon was divided and was tensile tested to failure. The tensile stress of medial/lateral patellar tendon was calculated. And the results were compared to that of finite element model. Results: At the knee 0°, 30°,60°flexion, when the load of vastus medialis oblique increased from 0N to 30N, there was no significant difference with regard to the tensile stress of medial patellar tendon (P>0．05) . At other conditions, when the load of vastus medialis oblique increased at the same position, there was significant difference with regard to the tensile stress of medial/lateral patellar tendon between every two adjacent conditions (p<0．05) . Total results showed with the load of vastus medialis oblique increased, the tensile stress of medial patellar tendon decreased, the tensile stress of lateral patellar tendon increased. The trend of the results accorded with that of finite element analysis.Conclusion: 1) With the load of vastus medialis oblique increased, the tensile stress of medial patellar tendon decreased, the tensile stress of lateral patellar tendon increased. This trend existed at the knee 0°, 30°, 60°flexion; 2) It is be evident the model were reasonable and consistent with experimental study. The model can be used to biomechanical study.PartⅤThe Clinical Results and Change of Muscle Function of DifferentTreatment in Athletes with Patellar TendinopathyObjectives: To evaluate the clinical results and change of muscle function after extracorporeal shock wave therapy(ESWT) and eccentric training in athletes with patellar tendinopathy. To evaluate the relationship of the clinical results and the change of the muscle function.Subjects and Methods: Forty-eight atheletes (60 knees) with patellar tendinopathy accepted treatment from January 2005 to August 2006．Subjects were divided to three groups: 1) physical therapy group: microwave and laser treatment, each was 15 minutes every time per day; 2) ESWT group: ESWT using 1,000 impulses, at a frequency of 4 Hz and an energy flow density of 0．08 mJ/mm2, 15 minutes every time, twice per week; 3) eccentric training group: eccentric quadriceps muscle training, once a day. The patients were evaluated before treatment and after eight weeks of follow-up. The outcome measure were: 1) Victorian Institute of Sport Assessment (VISA) ; 2) VMO: VL and TimeV_L-Time_VMO during isokinetic testing (60deg/s). The data of three groups were compared.Results: There was no significant difference between beginning and after treatment in physical therapy group with regard to every measurement (P>0．05) . In ESWT group, there was significant difference between beginning and after treatment with regard to VISA score (P<0．01) , but there was no significant difference between beginning and after treatment with regard to VMO: VL and Time_VL-Time_VMO (P>0．05) no matter in concentric period or eccentric period. In eccentric training group, there was significant difference between beginning and after treatment with regard to VISA score (P<0．01) and VMO: VL of concentric period and eccentric period, but there was no significant difference between beginning and after treatment with regard to Time_VL-Time_VMO (P>0．05) no matter of concentric period or eccentric period. Before treatment, there was no significant difference with regard to every measurement (P>0．05) among three groups. After treatment, compared to physical therapy group, eccentric training group had greater VISA score (P<0．01) , greater difference of VISA score between beginning and after treatment (P<0．05) and less VMO: VL of concentric or eccentric period (P＜0．05,P＜0．05) . Compared to ESWT group, eccentric training group had less VMO: VL of eccentric period (P＜0．05) . Compared to physical therapy group, ESWP group had greater VISA score (P<0．01) and greater difference of VISA score between beginning and after treatment (P<0．05) . In eccentric training group, the athletes who reduced the VMO: VL of concentric or eccentric period were prone to have good clinical results (P<0．05) . But in physical therapy group and ESWP group, we could not find such relationship between the change of muscle function and clinical results (P>0．05) .Conclusion: ESWT and eccentric training could get better clinical results than physical therapy. Eccentric training could change the abnormal muscle function (greater VMO: VL of concentric or eccentric period). But no muscle function changes were found in physical therapy group or ESWP group. In eccentric training group, the athletes who reduce the VMO: VL of concentric or eccentric period could get better clinical results.中图分类号R686．1...