Correlation between varus knee malalignment and patellofemoral osteoarthritis

Area of Science:

• Orthopedics
• Radiology
• Biomechanics

Background:

• Osteoarthritis (OA) of the knee is a prevalent degenerative joint disease.
• Varus alignment is a common feature in knee OA, potentially influencing disease progression.
• Patellofemoral joint involvement in varus knee OA requires further elucidation.

Purpose of the Study:

• To investigate the relationship between patellofemoral osteoarthritis (OA) and varus osteoarthritis of the knee.
• To identify the specific location of joint space narrowing in the context of varus knee OA.
• To assess the correlation between knee alignment parameters and the severity of patellofemoral OA.

Main Methods:

• Retrospective cohort study of 85 patients undergoing total knee arthroplasty for varus OA.
• Measurement of femorotibial angle, patellar tilt, and tibial tuberosity-trochlear groove (TT-TG) distance.
• Classification of patellofemoral OA severity using computed tomography.

Main Results:

• Significantly larger femorotibial angles and increased patellar tilt/TT-TG distance were observed with advancing patellofemoral OA stages.
• A strong correlation was found between TT-TG distance and patellar tilt (R(2) = 0.41, P < 0.001).
• Joint space narrowing predominantly occurred at the lateral facet of the patellofemoral joint, worsening with OA progression.

Conclusions:

• Patellofemoral OA contributes to varus knee malalignment, with a notable impact on the lateral facet.
• Patellar tilt and TT-TG distance are key indicators of patellofemoral OA severity in varus knees.
• Understanding these factors can inform preventive strategies and surgical interventions like high tibial osteotomy and total knee arthroplasty.