Sex-Specific Adolescent Development of the Trochlea and Distal Femoral Physis: A 3D Shape Modeling Study
Orthopaedic journal of sports medicine · 2026
Deep learning 3D modeling maps sex-specific trochlear and growth plate development in teens, useful groundwork, but no effect sizes given and no surgical protocol yet.
The paper
Cross-sectional retrospective imaging study, n=261 non-dysplastic knee MRIs from individuals aged 8-22 years, used to build sex-specific 3D shape models of distal femoral and trochlear development.
What they found
Deep learning-based 3D shape modeling showed proximal migration of the physis and deepening of the trochlea in both sexes between ages 13-19, with lateral trochlear depth consistently exceeding medial depth; after age 16, males showed a 'significantly greater' size-standardized lateral trochlear depth than females, but the abstract gives no effect size, confidence interval, or p-value for that comparison.
Study design
Cross-sectional, retrospective, Level of evidence 3 imaging study; 261 non-dysplastic knee MRIs across an 8-22 year age range were used to build sex-specific statistical shape models, this is descriptive anatomic characterization, not an interventional or outcome study.
Methodology
Different patients were sampled at each age point and treated as a proxy for a growth trajectory, so this cannot capture individual developmental change the way a true longitudinal cohort would. The MRIs are retrospective and presumably obtained for unrelated clinical indications, raising selection bias about how representative these knees are of normal development. The deep learning segmentation model's accuracy and inter-rater reliability against manual segmentation aren't reported in the abstract, and the key sex-difference finding is stated as significant without a quantified effect size or CI, so a reader can't judge its magnitude from what's given.
The appraisal
The sex difference in lateral trochlear depth after age 16 may be statistically significant, but without an effect size or CI there is no way to judge whether it is clinically meaningful for surgical planning. The design supports description of population-level anatomic patterns, not individual growth trajectories or causal claims about optimal surgical timing.
The gap
The cross-sectional substitution-for-longitudinal design and the unquantified magnitude of the male-female difference are the key limitations. The 261 MRIs were also clinically-indicated scans, not a healthy-volunteer screening sample, so this 'nondysplastic' cohort may still skew toward knees imaged for trauma or pain rather than a representative growth sample. Before this informs trochleoplasty timing you'd want longitudinal imaging in the same patients, an actual effect size with clinical thresholds, and confirmation the findings hold in a community-based sample.
Landmark context
This sits within the trochlear dysplasia and patellar instability literature built on classification systems like the Dejour classification, and extends prior anatomic work on pediatric trochlear development by applying deep learning 3D shape modeling rather than manual measurement; it is not a replication or refutation of a single landmark trial.
What to do Monday
This does not change Monday practice. It is hypothesis-generating anatomic reference data that may eventually help refine the age window for safer trochleoplasty in skeletally immature patients, but no surgical protocol change is supported by a descriptive shape-modeling study alone.
In practice
This doesn't change what you do Monday, in clinic or on the performance floor. In the clinic: if you're following an adolescent with patellar instability or trochlear dysplasia toward a trochleoplasty decision, know that trochlear depth and physeal position are still shifting through the mid-to-late teens and diverge by sex after 16, so a scan at 13 may not represent the anatomy at 17. That's a talking point for the surgical conversation, not a reason to change your own conservative management. On the performance floor, this is background knowledge, not a protocol: it reinforces why you monitor anterior knee symptoms and growth-plate-adjacent load through peak height velocity in adolescent athletes, particularly girls with instability episodes, but it hands you no new load threshold, test, or return-to-sport criterion. Don't let anyone use a shape-modeling paper to justify moving surgical timing earlier or later; that call belongs to the outcomes literature.
The five papers that matter — every week, free.
We read the whole sports-medicine, rehab & performance literature and appraise the papers worth your time.
Get the free weekly issueRelated appraisals
Read in your language: English · Français · Deutsch · Español · Italiano · Nederlands · Dansk · Svenska