Patella Alta and Trochlear Dysplasia as a Determinant of Patellar Tendon Lateralization and Inclination: A Cross-sectional MRI Study in Adolescents With Patellofemoral Instability

This retrospective case-control MRI study compared 142 adolescent knees with surgically treated patellofemoral instability (PFI) to 142 age/sex-matched controls, measuring two soft-tissue-based markers of patellar tendon alignment: the previously described patellar tendon-lateral trochlear ridge distance (PT-LTR) and a newly proposed patellar tendon inclination angle (PTIA). Both measures were markedly higher in PFI knees than controls (PT-LTR 9.76 vs 0.61 mm; PTIA 22.76° vs 11.09°, both P<.001), correlated with established risk factors like patella alta, trochlear dysplasia, and TT-TG distance, and showed good diagnostic accuracy (AUC 0.90 and 0.87, respectively) for distinguishing PFI from controls.

AI summary · from the full text · reviewed by Pukhraj Gaheer, Medical Student, Queen's University before publishing

Why it mattersIntroduces a new, easily measured MRI angle (PTIA) that may add diagnostic information about patellar tendon malalignment beyond standard bony measurements like TT-TG in adolescents being worked up for patellofemoral instability.

Presenting this at rounds? Start here

• ?If PTIA and PT-LTR are elevated in a patient with a normal TT-TG distance, should that change how aggressively you counsel about surgical stabilization versus bracing/physical therapy for patellofemoral instability?
• ?Given that patella alta and trochlear dysplasia both independently raise PT-LTR and PTIA, how might these tendon-based measurements influence your choice of concomitant procedures (e.g., tibial tubercle osteotomy, trochleoplasty) alongside MPFL reconstruction?