Abstract
Objectives:
Trochlear dysplasia is a leading contributor to patellofemoral instability, yet the developmental role of the trochlear physis in shaping trochlear morphology remains poorly understood. We hypothesised that selective closure of the trochlear physis would alter trochlear morphology in a predictable manner based on the region of growth arrest.
Methods:
Twelve New Zealand White rabbits underwent unilateral selective epiphysiodesis of the trochlear physis at either the medial, central, or lateral aspect (n=4 per group). Contralateral limbs served as internal controls. At 6 weeks postoperatively, gross morphology, micro-CT(µCT) measurements direct caliper assessments and histology were performed. µCT parameters including sulcus angle, trochlear depth, inclination, and facet symmetry were analyzed. Direct caliper measurements included trochlear width and ridge height and length. Paired t-tests compared treated versus control limbs within each group.
Results:
Selective epiphysiodesis altered trochlear morphology in a location-specific pattern. Lateral epiphysiodesis resulted in decreased proximal sulcus angle (p=0.005) and increased lateral trochlear depth measured on axial µCT images. Central epiphysiodesis increased medial trochlear depth (p=0.009) and medial trochlear inclination (p=0.007), with greater facet symmetry (p=0.016). Medial epiphysiodesis reduced lateral depth (p=0.030) and lateral inclination (p=0.031), with associated medial facet elongation (p=0.003). Direct caliper measurements showed increased trochlear width (p = 0.043) and increased medial trochlear ridge height (p = 0.043) as a result of central epiphysiodesis. No cartilaginous changes were noted grossly or histologically.
Conclusion:
The trochlear physis significantly contributes to shaping the trochlear groove during skeletal growth. Targeted physeal closure alters trochlear morphology, supporting the potential for growth modulation strategies in managing early dysplastic changes. A central epiphysiodesis could be utilized to increased medial facet depth and symmetry between the medial and lateral trochlea facet.