Does interlimb knee symmetry exist after unicompartmental knee arthroplasty?

Area of Science:

• Orthopedic surgery
• Biomechanics
• Gait analysis

Background:

• Unicompartmental knee arthroplasty (UKA) is a treatment for localized knee disease.
• Concerns exist regarding the restoration of normal knee kinematics, especially with lateral UKA.
• The impact of UKA on knee kinematics and interlimb symmetry remains unclear.

Purpose of the Study:

• To assess knee kinematics during stair ascent in patients with medial- (MED-UKA) and lateral-UKA (LAT-UKA).
• To determine if knee kinematics are symmetrical between operated and non-operated limbs after UKA.

Main Methods:

• 17 MED-UKA and 9 LAT-UKA patients with healthy contralateral limbs participated.
• Motion capture and force platforms analyzed stair ascent kinematics and temporal events.
• Interlimb symmetry was evaluated against clinically meaningful thresholds (5% stride time, 5° angle).

Main Results:

• Neither MED-UKA nor LAT-UKA groups showed clinically significant mean interlimb kinematic differences.
• Approximately 50% of patients in both groups exhibited some degree of asymmetry.
• Asymmetry occurred with similar frequency in both the operated and non-operated limbs.

Conclusions:

• Most patients undergoing UKA achieve kinematic interlimb symmetry during stair ascent.
• Factors other than the UKA itself may influence interlimb asymmetry.
• Medial- or lateral-UKA can potentially restore normal knee function for daily activities.