Trochear dysplasia is a condition where the trochlear groove is abnormal, usually at its upper end, at which point the groove is abnormally flat or even heaped into a 'bump'.
Mild trochlear dysplasia with a shallow trochlear groove.
More severe situation where the upper trochlea has no groove at all.
Instead of being convex, the trochlear at its upper end forms a concave 'bump', and the patella finds no comfortable groove into which to engage.
Trochlear dysplasia and kneecap instability
Trochlear dysplasia is commonly associated with an unstable patella (kneecap), and patellar dislocation.
The effect of trochlear dysplasia on patellofemoral biomechanics: a cadaveric study with simulated trochlear deformities. Van Haver A, De Roo K, De Beule M, Labey L, De Baets P, Dejour D, Claessens T, Verdonk P. Am J Sports Med. 2015 Jun;43(6):1354-61.
Trochlear dysplasia: imaging and treatment options. Batailler C and Neyret P. EFORT Open Rev. 2018 May; 3(5): 240–247.
Arthroscopic deepening trochleoplasty for chronic anterior knee pain after previous failed conservative and arthroscopic treatment. Report of two cases. Blønd L. Int J Surg Case Rep. 2017; 40: 63–68.
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VIDEO: Putting trochlear dysplasia into context