Patellar Morphology in Recurrent Lateral Patellofemoral Instability: Associations With Risk Factors and Postoperative Outcomes.

Background: Patellar morphology, most commonly described by the Wiberg classification, is a potential risk factor for recurrent lateral patellofemoral instability. However, the Wiberg classification has not been widely used in this population, and therefore its clinical utility remains unclear. Purpose: (1) To determine the incidence of Wiberg types and to explore relationships between the Wiberg classification and risk factors in a population of patients with recurrent lateral patellofemoral instability. (2) To evaluate the relationship between the Wiberg classification and disease-specific quality of life outcomes after primary medial patellofemoral ligament (MPFL) reconstruction. Study Design: Cohort study; Level of evidence, 3. Methods: A population of 447 patients who underwent MPFL reconstruction for recurrent instability was enrolled. Preoperative demographic and pathoanatomic data were collected prospectively. Intrarater reliability of the Wiberg classification was assessed using a weighted kappa (κw). Pearson and Spearman correlation coefficients, as well as ordinal logistic regression, were used to explore relationships between the Wiberg classification and risk factors for patellofemoral instability. A 1-way analysis of variance assessed preoperative and 24-month postoperative Banff Patellofemoral Instability Instrument (BPII) scores in relation to the Wiberg classification. Results: The study enrolled 447 patients, including 539 knees (21.5% male knees; 78.5% female knees), with a mean age at first dislocation of 14.9 years (SD, 6.1). The distribution of patellae by the Wiberg classification was 30.6% type 1 (n = 165), 47.1% type 2 (n = 254), and 22.3% type 3 (n = 120). κw intrarater agreement for the Wiberg classification was substantial (κw = 0.75). An ordinal logistic regression demonstrated a statistically significant -2 log likelihood model ( Conclusion: In this large cohort of patients with recurrent patellofemoral instability, a statistically significant ordinal logistic regression model, including the combination of trochlear dysplasia, WARPS/STAID score, and age at time of first dislocation, predicted Wiberg classification. No relationship was determined between the Wiberg classification and pre- or postoperative BPII 2.0 quality of life scores.