An investigation into the cellular-level adverse effects of tourniquet use on the infrapatellar fat pad in primary total knee arthroplasty: A prospective randomized study.

OBJECTIVE

This study aimed to examine the cellular-level adverse effects of tourniquet use on the infrapatellar fat pad (IPFP) in patients undergoing primary total knee arthroplasty (TKA).

METHODS

Infrapatellar fat pad samples were collected in a prospective, randomized design to compare 2 groups of primary TKA patients with a tourniquet (T) and without a tourniquet (NT). The study included 80 knees of 58 patients with a mean age of 65.91 ± 9.04 years. The authors collected 3 samples from the T group (after exposure to the fat pad "t1," just before deflating the tourniquet "t2," just before fascia closure "t3") and 2 samples from the NT group (t1 and t3) for each patient. BAX, Bcl-2, and HIF-1α staining showed the extent of cellular hypoxia and apoptosis in IPFP cells, whereas the oxidative stress index (OSI) was determined using a biochemical method. The Knee Injury and Osteoarthritis Outcome Score (KOOS), Knee Society Score (KSS), and Kujala score were used as clinical outcome measures.

RESULTS

The mean HIF-1α, BAX/Bcl-2, and OSI scores across all time points were significantly higher in the T group than in the NT group (p<0.001) (d=1.16, 2.9, and 0.9, respectively). The mean BAX/Bcl-2 (P=.030) and HIF-1α (P < .001) scores significantly peaked at t2 in the T group (d=-1.2 and -3.9, respectively). The OSI had higher levels at t1 (P=.011) and t3 (P=.073) (d=0.2 and 0.1, respectively) than at t2 in the T group. The third-month postoperative follow-up revealed that the mean KOOS, KSS, and Kujala score improved significantly compared to the baseline preoperative values (P < .001); however, there was no difference between the T and NT groups regarding the maximum and total knee range of motion or clinical outcome scores.

CONCLUSION

Evidence from this study has shown that tourniquet use during primary TKA may be associated with significantly increased cellular hypoxia, oxidative stress, and apoptosis in the IPFP.

LEVEL OF EVIDENCE

Level I, Therapeutic study.