Osteoarthritic knees have a highly variable patellofemoral alignment: a systematic review

Area of Science:

• Orthopedics
• Radiology
• Biomechanical Engineering

Background:

• Osteoarthritis (OA) commonly affects the knee joint, leading to pain and functional limitations.
• Patellofemoral (PF) alignment and trochlear morphology are critical factors in knee biomechanics.
• Variability in PF alignment within osteoarthritic knees requires further investigation.

Purpose of the Study:

• To systematically review and evaluate the variability of patellofemoral alignment and trochlear morphology in osteoarthritic knees.
• To identify key parameters defining PF alignment and assess their range in OA.
• To inform surgical planning for total knee arthroplasty (TKA) to mitigate postoperative anterior knee pain (AKP).

Main Methods:

• Systematic review of studies reporting PF alignment measurements in osteoarthritic knees (patients >40 years old).
• Searched MEDLINE and EMBASE databases adhering to PRISMA guidelines.
• Extracted data on sulcus angle (SA), femoral trochlear depth (FTD), patellar tilt angle (PTA), lateral patellofemoral angle (LPFA), lateral femoral trochlear inclination (LFTI), and tibial tubercle-trochlear groove distance (TT-TG).
• Assessed methodological quality using a 14-item checklist.

Main Results:

• Eight studies met the inclusion criteria.
• Reported mean values for SA ranged from 120° to 141.1° ± 7.7°.
• Reported ranges for other parameters included FTD (5.8 mm ± 1.4), PTA (-0.1° ± 3.3 to 10.3° ± 5.7), LPFA (5.8° ± 5.4 to 17°), LFTI (23.2° ± 5.0 to 27.1° ± 4.4), and TT-TG (5.8 mm ± 5.4).

Conclusions:

• Patellofemoral alignment in osteoarthritic knees exhibits greater variability than anticipated.
• Individual preoperative PF alignment assessment is recommended for surgeons to optimize outcomes and reduce AKP after TKA.
• 3D-CT imaging is suggested as a valuable tool for precise PF alignment analysis.