Curr Rev Musculoskelet Med (2008) 1:53–60 55 Fig. 2 Medial synovial plica palpation (Plica snap test) Fig. 3 Palpation of meniscofemoral portion of superﬁcial medial collateral ligament while applying valgus stress at 30 of knee ﬂexion subluxation episode with injury to the medial patellofe- moral ligament. The lateral patellar apprehension test, performed with the knee ﬂexed to approximately 45 of knee ﬂexion, can help to determine if there has been injury to the medial patellofemoral ligament by applying a lateral translation force to the patella when it is ﬂexed to approx- imately 45 of knee ﬂexion and assessing if this translation causes pain or an apprehensive feeling like the patella will dislocate (Fig. 4). This pain should be different from pain produced when the plica is rolled under ones ﬁngers. Fur- ther, one should make sure that the pain over the medial aspect of the knee is not directly due to localized or diffuse Fig. 4 Lateral translation of patella areas of chondromalacia of the patellofemoral joint. In this instance, one would roll the superior and inferior poles of the patella both proximally and distally, as well as medially and laterally, in the trochlear groove, to determine if there is any true retropatellar crepitation with translation of the patella in the trochlear groove (Fig. 5a, b). This evaluation is different from assessing for crepitation of the patellofe- moral joint with active ﬂexion and extension of the knee (Fig. 6a, b) as many of these patients may have catching of their medial plica causing the crepitation with active ﬂexion and extension of the knee rather than true patellofemoral chondromalacia causing this auditory occurrence. In addi- tion, one should assess for hamstring tightness, which can cause stress to the anterior aspect of the knee, by assessing the hamstring-popliteal angle (Fig. 7) and by palpation of the main hamstring attachment sites of the knee (pes anserine bursa (Fig. 8), semimembranosus bursa (Fig. 9), and biceps bursa (Fig. 10)). When one is not sure about the diagnosis of medial synovial plica irritation and it is difﬁcult to determine if the patient has a true intraarticular or an extraarticular pathology over this area of the knee, one can conﬁrm the diagnosis with an intraarticular anesthetic injection of 1% Lidocaine (Fig. 11). In this instance, the injection should be intraarticular and one should not attempt to inject directly into the medial synovial plica. This distinction is important to differentiate because the plica is actually intraarticular. If one does have good pain relief with an intraarticular anesthetic injection, one can be sure that the pathology is intraarticular rather then extraarticular over this portion of the knee. Although one series of intraplical injections reported good results [15], it has also been reported, and we also concur, that injection directly into the