Patella Alta and Trochlear Dysplasia as a Determinant of Patellar Tendon Lateralisation and Inclination: A Cross-sectional MRI Study in Adolescents With Patellofemoral Instability
The American Journal of Sports Medicine · 9 Sept 2026
† Impact is the editorial-priority score. All scores are out of 100. Clinical is a stored clinical-importance score from the earlier method; it has not been recalculated.
Why it matters
Introduces 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.
The evidence
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.
A coherent primary effect estimate is unavailable. Clinical relevance does not estimate treatment benefit.
Why this rigour score?
Historically controlledDesign starting point: 19.2
Raised the score
- Blinded outcome assessment+3.4
Lowered the score
- A single centre's own patients−3.4
Methods at a glance
Recorded assessment- Confounding adjustmentMatching or stratification
- Covariate balance confirmedNot reported
- Outcome assessors blindedMet
- Comparable start of follow-upNot applicable
- Adequate statistical powerNot reported
- Prospective registrationNot applicable
Not reported does not mean not done. Checks have different weights; this is not a count of boxes ticked.
See the full score breakdown
- Study design starting point
- 19.2
- Blinded outcome assessment
- +3.4
- A single centre's own patients
- −3.4
- Journal prior (not an observed method)
- +2.7
- Final rigour score rounded
- 22 / 100
Study design sets the starting point and a ceiling of 55. Recorded methods then adjust the score. Points are shown to one decimal place; the final score uses unrounded values.
Checklist from the stored appraisal. “Not met” describes the recorded criterion; it does not always produce a deduction. This overview supports reading the full study.
For journal club
1.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?
2.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?
Original publication title
Patella Alta and Trochlear Dysplasia as a Determinant of Patellar Tendon Lateralization and Inclination: A Cross-sectional MRI Study in Adolescents With Patellofemoral Instability