[en] Background: Patellofemoral pain syndrome and patellar instability are a common cause of anterior knee pain and functional deficit and they mainly affect young women. The treatment is usually focused on the selective retraining of the vastus medialis oblique, although it is not clear if this is better than general strengthening of the quadriceps nor if you can activate selectively this muscle. Objective: to check the efficacy of selective strengthening of vastus medialis oblique in comparison with general quadriceps strengthening in patients with patellofemoral pain syndrome and patellar instability. Methods: This review has been done using PubMed, PEDro, Scopus, SPORTdiscus, Cochrane and CINAHL databases. Articles in Spanish, English and Portuguese that addresses the efficacy of selective retraining of vastus medialis oblique in comparison with general quadriceps strengthening in patients with patellofemoral pain syndrome, patellar instability or a medical history related with these pathologies and, finally, articles analyzing changes produced in the muscle activity and/or VMO and VL ratio in different exercises in healthy and pathological subjects have been included. Outcomes: 20 studies were included, 12 in healthy subjects and 8 in pathological subjects. 11 were uncontrolled clinical trial, 1 controlled trial, 3 randomized controlled trial, 1 cross sectional study, 3 cross-over study and 1 randomized cross-over study. Conclusions: It cannot be concluded that selective retraining of the VMO muscle or exercises focused on VMO activation are more effective than a general quadriceps strengthening program.

[gl] Introdución: a síndrome femoropatelar e a inestabilidade patelar son causa común de dor anterior de xeonllo e déficit funcional, afectando principalmente a mulleres novas. O tratamento soe estar centrado no reentrenamento do vasto medial oblicuo, inda así, non está claro se é mellor que o fortalecemento xeral do cuádriceps ou se se pode activar selectivamente este músculo. Obxectivos: comprobar a efectividade do reentrenamento selectivo do vasto medial oblicuo en relación ao fortalecemento do cuádriceps en xeral na síndrome femoropatelar e inestabilidade rotuliana. Material e métodos: esta revisión bibliográfica realizouse usando as bases de datos PubMed, PEDro, Scopus, SPORTdiscus, Cochrane e CINAHL. Estudos en castelán, inglés e portugués que tratan sobre a efectividade do reentrenamento do vasto medial oblicuo frente ao fortalecemento do cuádriceps en xeral en pacientes con síndrome femoropatelar, inestabilidade patelar ou suxeitos con historia destas patoloxías e, finalmente, estudos que analicen os cambios producidos na actividade e/ou ratio de VMO y VL en diferentes exercicios en suxeitos sans y patolóxicos. Resultados: inclúense 20 estudos, 12 estudan a suxeitos sanos e 8 a suxeitos patolóxicos. Dentro dos estudos, 11 son ensaios no controlados, 1 é un ensaio controlado, 3 son ensaios controlados aleatorizados, 1 é un estudo transversal, 3 son ensaios cruzados e 1 es un ensaio cruzado aleatorizado. Conclusións: non se pode concluir que o reentrenamento ou os exercicios centrados na activación do VMO sexan máis efectivos que un programa de fortalecemento de cuádriceps en xeral.