Isolated Medial Patellofemoral Ligament Reconstruction Reduces Patellar Height and Is Associated With Quadriceps...

Area of Science:

• Orthopedic surgery
• Biomechanics
• Radiographic analysis

Background:

• Patellofemoral instability is a common orthopedic condition.
• Medial patellofemoral ligament reconstruction (MPFLR) is a standard surgical treatment.
• The effect of MPFLR on patellar height and its correlation with patient factors require further investigation.

Purpose of the Study:

• To evaluate the impact of isolated double-limbed MPFLR on patellar height using the Caton-Deschamps Index (CDI).
• To determine the association between preoperative patella alta and postoperative quadriceps dysfunction with changes in CDI.
• To analyze radiographic outcomes following MPFLR in patients with patellofemoral instability.

Main Methods:

• Retrospective review of 81 knees undergoing isolated MPFLR between 2016 and 2022.
• Measurement of Caton-Deschamps Index (CDI) on preoperative and postoperative lateral radiographs.
• Assessment of preoperative patella alta (CDI > 1.2) and postoperative quadriceps function (straight leg raise).
• Statistical analysis including Wilcoxon signed-rank, Mann-Whitney U, and linear regression tests.

Main Results:

• A significant decrease in mean CDI was observed post-MPFLR.
• Patients with preoperative patella alta demonstrated a greater reduction in CDI.
• Increasing preoperative CDI correlated with greater CDI change.
• CDI reduction was influenced by postoperative quadriceps function, with larger decreases in patients with extensor lag.

Conclusions:

• Isolated double-limbed MPFLR leads to a significant reduction in patellar height (CDI).
• Preoperative patella alta and impaired quadriceps function are associated with greater CDI reduction post-surgery.
• Early postoperative CDI decreases may be partly artifactual due to transient quadriceps inhibition.