Anatomic patellar instability risk factors in primary lateral patellar dislocations do not predict injury patterns:...

Area of Science:

• Orthopedic surgery
• Sports medicine
• Radiology

Background:

• Lateral patellar dislocation (LPD) is a common knee injury.
• Understanding injury patterns in primary LPD is crucial for effective management.
• Previous notions about injury patterns require clarification through detailed analysis.

Purpose of the Study:

• To describe the specific injury patterns in patients experiencing their first lateral patellar dislocation (LPD).
• To correlate magnetic resonance imaging (MRI) findings with anatomical risk factors for patellar instability.
• To provide clarity on commonly held beliefs regarding injury characteristics in primary LPD.

Main Methods:

• Prospective study of 157 patients with primary LPD between 2008-2012.
• MRI analysis to assess cartilage lesions, medial patellofemoral ligament (MPFL) injuries, and bone bruising.
• Evaluation of anatomical risk factors including patella alta, trochlear dysplasia, increased TT-TG, and lateral patella tilt.

Main Results:

• MPFL injuries were common, with complete ruptures in 44% and partial in 43%.
• Chondral injuries occurred in 43% on the patella and 7% on the lateral femoral condyle.
• Skeletally immature patients showed a higher risk of isolated patellar MPFL and chondral injuries.
• No clear relationship was found between bone bruising, MPFL, or chondral injury location/severity and anatomical risk factors.

Conclusions:

• Anatomical risk factors do not predict injury patterns in primary LPD.
• MPFL and chondral injuries, along with bone bruising, are frequent findings.
• Medial patellotibial ligament (MPTL) tears occur in patellar-based medial retinacular injuries.
• Skeletal immaturity impacts injury location, with isolated patellar injuries more common in younger patients.