The collateral ligament flexion-extension test (CLEFT) in total knee replacement

Area of Science:

• Orthopedic Surgery
• Biomechanics

Background:

• Total knee arthroplasty (TKA) often addresses valgus or varus deformities.
• Accurate assessment of collateral ligament balance is crucial for successful TKA outcomes.
• Preoperative planning aims to minimize intraoperative soft tissue releases.

Purpose of the Study:

• To introduce and validate the collateral ligament extension-flexion test (CLEFT) as a simple preoperative clinical assessment.
• To determine if CLEFT can reliably predict the need for soft tissue adjustment in TKAs with preoperative deformities.
• To evaluate the test's ability to identify knees where bony correction suffices.

Main Methods:

• The CLEFT was prospectively applied to 44 consecutive TKA patients with >10 degrees valgus or varus deformity in extension.
• The test assesses if a deformity corrects in flexion.
• Correlation between CLEFT results and intraoperative need for collateral ligament release was analyzed.

Main Results:

• The CLEFT was positive in 34 patients, none of whom required ipsilateral collateral ligament release.
• All 10 patients with a negative CLEFT result required soft tissue adjustment.
• The test demonstrated high sensitivity in predicting balanced collateral ligaments.

Conclusions:

• The CLEFT is a reliable and simple preoperative test for assessing collateral ligament balance in TKA.
• It accurately predicts which knees with deformity can be managed with bone cuts alone, avoiding soft tissue release.
• The findings support prioritizing bony resection over soft tissue adjustment when indicated by the CLEFT.