In Vitro Evaluation of Lateral Femur Condyle Free Chondral Fragment Swelling after Soaking in Normal Saline

After traumatic knee injuries, chondral fragments can avulse off bone with the progeny fragment becoming a loose body. The loose fragment may be larger than expected when trying to surgically repair the fragment back to its original site. The purpose of this study was to determine whether a loose chondral fragment from the lateral femur condyle would increase in size and weight after soaking in normal saline (NS) for 14 days.

Twelve 6-mm OAT (osteoarticular transfer) plugs were harvested from 6 cadaver knees on the lateral femoral condyle to simulate a chondral fragment. The chondral fragments were then placed inside an airtight specimen container with NS (0.9% sodium chloride) and were measured over 14 days.

After 14 days, the chondral fragments showed no increase in diameter as they measured an average of 5.567 ± 0.448 mm on Day 1 and 5.702 ± 0.253 mm on Day 14 (P = 0.183). The chondral fragments showed an increase in mass from an average of 0.058 ± 0.012 g on Day 1 to 0.073 ± 0.012 g on Day 14 (P < 0.001) and an increase in thickness from an average of 2.038 ± 0.346 mm on Day 1 to 2.229 ± 0.297 mm on Day 14 (P = 0.033).

Chondral fragments in NS increase in mass and thickness over time, but do not change in diameter. When surgeons are evaluating loose chondral fragments for fixation, they should consider that these fragments may appear thicker than the recipient location.