Patellar Shape is Associated With Femoral Trochlear Morphology in Individuals with Mature Skeletal Development

Background: As several studies have detected correlations between patellar and femoral trochlear development, this raises the question of whether patellar shape is associated with trochlear developmental outcomes.Methods: Patellar shape and femoral trochlear morphology were retrospectively analyzed in 240 subjects, of whom 80 each were classified as having Wiberg type I, II, and III patellae (groups A, B, and C, respectively). The sulcus angle (SA), lateral trochlea inclination angle (LTA), medial trochlear inclination angle (MTA), lateral facet length (LFL), medial facet length (MFL), lateral trochlear height (LTH), medial trochlear height (MTH), trochlea sulcus height (TH), and lateral-medial trochlear facet distance (TD) were analyzed as a means of evaluating trochlear morphology. Trochlear depth, trochlear condyle asymmetry, and trochlear facet asymmetry were additionally calculated, and differences in trochlear morphology and correlations between trochlear morphology and patellar shape were evaluated.Results: The femoral trochlear parameters of patients in group A differed significantly from those of patients in groups B and C. No significant differences between groups B and C were evident. Patellar shape was positively correlated with LTA, MTA, MFL, trochlear index trochlear condyle asymmetry, and trochlear facet asymmetry, and was negatively correlated with SA.Conclusions: These data indicated that patellar shape and trochlear morphology are related to one another. Relative to patients with Wiberg type II and III patellae, those with Wiberg type I patellae exhibited an increased trochlear inclination angle and a greater trochlear facet and condyle asymmetry, as well as a decreased SA.Trial registration: Retrospectively registered

TROCHLEAR MORPHOLOGY DEVELOPMENT: STUDY OF NORMAL PEDIATRIC KNEE MRIS

Introduction: Trochlear dysplasia is a known risk factor for patellar dislocations yet normal trochlea development is not well described. This study will define the articular cartilage and subchondral trochlear morphology development in pediatric patients using MRI evaluation. Methods: Retrospective knee MRI review including patients aged 3-16 years with non-patellofemoral related diagnoses. ICD-9/ICD-10 codes identified eligible study patients. Measurements of the trochlea were made based on previously established methods using the axial MRI image just distal to the physis at the deepest portion of the trochlear groove. Three linear (Lateral Trochlear Height (LTH), Medial Trochlear Height (MTH), Central Trochlear Height (CTH)) and three angular (Sulcus Angle (SA), Lateral Trochlear Slope (LTS), Medial Trochlear Slope (MTS)) were made at the Articular Cartilage (AC) and Subchondral Bone (SCB) (Figure 1). Twelve measurements were made independently by two study authors. Interrater reliability was assessed. Trochlea measurements were summarized across age quartiles: 1st (age 5.1 - 8.3y), 2nd (8.3 - 11.5y), 3rd (11.5 - 14.3y), 4th (14.3 - 16.9y). Associations between age and trochlea measures were assessed using linear regression with Huber-White adjusted standard errors. Results: 246 knee MRIs from 230 patients were included in this study. 113 patients (51%) were female while 117 (49%) were male. 116 MRIs (47%) were of the Left knee and 130 (53%) were Right knee. Average patient age was 11.4±3.4 years. Interrater agreement was high (ICC values >0.7). Mean values for measurements are presented by age quartiles (Table 1). LTH, MTH, and CTH showed linear increase with age (range 2 to 2.6 mm per year, p<0.001). SA, LTS, MTS measured at the AC showed no change with age (p>0.05) however LTS and MTS measured at SCB showed significant increases with age (0.6 and 0.9 degrees per year, p<0.001) while SA showed a decrease with age (-1.4 degrees per year, p<0.001). There were no significant differences found in the age associations by laterality, left vs right. There were no gender differences in the age associations for SA, LTS, MTS (p>0.05) however for MTH, LTH, and CTH, males were found to have a significantly greater growth rate (p<0.001). Conclusions: This study found an increase in articular cartilage and subchondral bone MTH, LTH, and CTH over time as well as an increase in subchondral bone LTS, MTS, and SA. However, no significant change in articular cartilage LTS, MTS, or SA was found. This normative data indicates that articular cartilage angles determine final trochlear morphology. [Table: see text][Figure: see text]

Rotating dome trochleoplasty: An experimental technique for correction of patellar luxation using a feline model

SummaryThe purpose of this study was to compare a trochlear block recession to a rotating dome trochleoplasty, a novel technique for the correction of patellar luxation in small animals. Twenty-eight limbs were used from 14 feline cadavers. With the stifles in flexion and extension, computed tomography was utilized to compare width and depth of the trochlea, medial trochlear ridge height, trochlear articular surface area preserved, patellar contact articular surface area, patellar area covered by the trochlear ridges and patellar tilt angle. The results of this study demonstrated that a rotating dome trochleoplasty is superior to a trochlear block recession with regard to medial trochlear height, trochlear width, trochlear depth and trochlear surface area preservation. The results of this study support further biomechanical evaluation of this technique which eventually may lead to clinical trials.