The biomechanical research of knee osteoarthritis patients under different angular velocities based on the characteristic multichannel surface electromyography / 中国康复医学杂志

Objective:To observe and analyze the surface electromyography activity of quadriceps femoris of knee osteoar-thritis(KOA)patients. Method:The surface electromyography of vastus lateralis,rectus femoris,and vastus medialis were recorded and analyzed in 30 KOA patients and 30 normal people during isokinetic knee flexion or extension at veloci-ties of 60 °/s,90 °/s or 180 °/s.We also record clinical indicators(muscle thickness and degree of knee pain)of the KOA group and evaluate the correlation between electromyographic data and clinical indicators. Result:Compared with the healthy control group,the KOA group had significantly lower knee extensor mo-ment during isokinetic knee flexion or extension at velocities of 60°/s(P＜0.001),90°/s(P＜0.01),or 180°/s(P＜0.01).Statistics showed that there were significant differences in the median frequency difference rate of vastus lateralis(P＜0.05)and root mean square value of rectus femoris(P＜0.01)between the healthy control group and the KOA group under 60°/s angular velocities.There was a significant difference in the root mean square value of rectus femoris(P＜0.05)between the two groups at velocities of 90°/s.Statistics revealed that the median frequency difference rate(P＜0.05)and root mean square value(P＜0.05)of rectus femoris had changed significantly at the velocities of 180°/s.The results of both multiple regression and random forest algo-rithm showed that knee extensor moment was the strongest predictor between electromyographic characteristics and clinical indicators. Conclusion:The strength of quadriceps femoris in KOA patients was decreased.Thus,the patient may need more muscles to complete the same action,which was easy to cause muscle fatigue.The knee extensor moment was closely related to the quadriceps femoris thickness and the degree of knee pain.It offers important advantag-es for the diagnosis and assessing the severity,which may provide the way for the future study of KOA.

Realineamiento Proximal del Mecanismo Extensor en la Luxación Congénita de la Rótula en Niños y Adolescentes / Proximal Realignment of the Extensor Mechanism in Congenital Dislocation of the Knee in Children And Adolescents

Introducción La luxación congénita de la rótula (LCR) es una entidad poco frecuente. El diagnóstico precoz suele ser difícil porque la rótula en el recién nacido es pequeña y de difícil palpación. El tratamiento no quirúrgico ha demostrado ser ineficaz. El enfoque terapéutico de esta patología requiere de la liberación externa y extensa del cuádriceps, el avance del vasto interno oblicuo y de la transferencia o hemitransferencia del aparato extensor. Materiales y métodos se busca evaluar la funcionalidad de los pacientes tratados quirúrgicamente mediante realineamiento proximal del mecanismo extensor por la técnica descrita por Green y modificada por los autores. Desde el año 2000 hasta el año 2015 se recolectaron 15 pacientes (20 rodillas) con diagnóstico de LCR tratados quirúrgicamente mediante la técnica descrita. Resultados Los resultados postoperatorios fueron evaluados mediante el cuestionario Kujala: 93.8/100 en promedio. Discusión El tratamiento de la LCR es un desafío y más aún si se encuentra asociada a retracción idiopática del recto anterior. Los resultados clínicos y funcionales obtenidos sugieren que la recolocación anatómica y estable de la rótula dentro de la tróclea femoral permite una satisfactoria alineación extensora del cuádriceps, desapareciendo su acción flexora inicial, lo que permite la elongación progresiva del mecanismo extensor durante las fases postoperatorias de rehabilitación. La técnica quirúrgica descrita ofrece una buena alternativa para el tratamiento de esta infrecuente patología congénita de la rodilla.

Background Congenital dislocation of the patella (CDP) is a rare condition. The early diagnosis is difficult, as the patella in the newborns is small and also difficult to recognise. The therapeutic approach of this disorder requires the extended and external release of the quadriceps, the forward movement of the internal oblique vastus, and the transfer or hemi-transfer of the extensor compartment. Methods To review the functionality of those patients who have received surgical treatment with proximal realignment of the extensor mechanism using Green's surgical technique and the one modified by the author. Between the years 2000 and 2015, a total of 15 patients with 20 knees found to have had congenital dislocation of the patella, and had received the abovementioned surgical treatment. Results The post-operative results were evaluated using the Kujala questionnaire, which gave a mean result of 93.8 / 100. Discussion The CDP treatment is a challenge, and even more so if it is associated with an idiopathic retraction of the anterior rectus. The clinical and functional results obtained suggest that an anatomic and stable realignment of the patella in the femoral trochlea allows a satisfactory extensor alignment of the quadriceps. This leads to the disappearance its initial flexor action, which allows the gradual elongation of the extensor mechanism during the postoperative phases of rehabilitation. The surgical technique described offers a good alternative for the treatment of this rare congenital disorder of the knee.

Low-frequency fatigue at maximal and submaximal muscle contractions

Skeletal muscle force production following repetitive contractions is preferentially reduced when muscle is evaluated with low-frequency stimulation. This selective impairment in force generation is called low-frequency fatigue (LFF) and could be dependent on the contraction type. The purpose of this study was to compare LFF after concentric and eccentric maximal and submaximal contractions of knee extensor muscles. Ten healthy male subjects (age: 23.6 ± 4.2 years; weight: 73.8 ± 7.7 kg; height: 1.79 ± 0.05 m) executed maximal voluntary contractions that were measured before a fatigue test (pre-exercise), immediately after (after-exercise) and after 1 h of recovery (after-recovery). The fatigue test consisted of 60 maximal (100 percent) or submaximal (40 percent) dynamic concentric or eccentric knee extensions at an angular velocity of 60°/s. The isometric torque produced by low- (20 Hz) and high- (100 Hz) frequency stimulation was also measured at these times and the 20:100 Hz ratio was calculated to assess LFF. One-way ANOVA for repeated measures followed by the Newman-Keuls post hoc test was used to determine significant (P < 0.05) differences. LFF was evident after-recovery in all trials except following submaximal eccentric contractions. LFF was not evident after-exercise, regardless of exercise intensity or contraction type. Our results suggest that low-frequency fatigue was evident after submaximal concentric but not submaximal eccentric contractions and was more pronounced after 1-h of recovery.

Lipoma Arborescens with Unilateral Knee Extensor Weakness: A case report

Lipoma arborescens is a rare intra-articular lesion characterized by villous lipomatous proliferation of the synovial tissue, usually found in knee. Patients with this benign condition are seen with progressive, painless swelling of the joint. We presented a case of 35 year old man with 3 year history of painless swelling in right knee. The symptom waxed and waned having about 1 year interval. The swelling was not related to alcohol intake and walking. Physical examination revealed severe effusion in right knee. The active range of motion was full and patient explained some tenderness on lateral side of patello-femoral joint. There were no abnormalities in knee X-ray but magnetic resonance image revealed a villous proliferation in suprapatella pouch. There were no significant abnormalities in blood test. Joint fluid analysis did not reveal any cause of swelling and effusion. In evaluation of isokinetic exercise, there was significant weakness of knee extensors.

Analysis of Torque Curve in Isokinetic Knee Dynamometer

OBJECTIVE: To analyze the patterns of isokinetic knee torque curves in normal population and determine the characteristics of those curves. METHOD: Two hundred and eightly-six normal subjects were included. The isokinetic knee torque curves were divided into three parts; to the angle of peak torque generation, to the point 10~20 degrees prior to end of joint motion, and to the end of joint motion. Each part was classified as convex(1), flat(2) and concave(3) type according to the shape. The curves were named such as 1-2-2 in order. Types of the curves, peak torque, angle of knee at peak torque, total acceleration energy, age, and sex of the subjects were compared. RESULTS: For knee extensors, frequencies of the curve types were 1-2-2(A), 1-2-1(B), 1-3-1(C), and 1-3-2(D). Mean ages of type A and B curves were slightly higher than types of C and D. Mean peak torque was greatest in type D. For knee flexors, the frequencies were 1-2-2(A), 1-2-1(B), and 1-1-2(C). Female predominance were found in type B while type C was found mostly in male. Mean peak torque was greatest in type C. CONCLUSION: The most common torque curve type was 1-2-2 for knee extensors and flexors. Torque curve types of knee extensors showed differences in age and torque curve types of knee flexors showed differences in sexual distribution.