S. Bitting

C.B. Frank

Objective: To determine the effect that systemic administration of NSAIDs have on early and intermediate ligament healing.

Subjects: 138 New Zealand White rabbits underwent a bilateral surgical MCL transection. The rabbits where then divided into three treatment groups.

Design: After undergoing MCL injury, rabbits received either Ibuprofen 18mg/kg BID, a COX-2 inhibitor (DFP) 3mg/kg daily, or a placebo sugar solution. Animals are housed one per cage and allowed unrestricted activity. MCLs were tested after 3, 6, and 14 weeks of healing.

Outcome Measures:

Cross sectional area (Chimich et al. 1991; Frank et al. 1983a)
Inflammatory cells per high powered field (Brook et al. 1997)
Low load cyclic creep at 20-30% failure strength (Thorton et al. 2000)
Stiffness (Frank et al. 1983a, Chimich et al. 1991)
Ultimate failure strength (Frank et al. 1983a, 1994 Chimich et al. 1991)
Water content (Thorton et al. 2000)
Collagen concentration (Frank et al. 1983a, 1995)

Results: At three weeks of healing NSAID treatment resulted in a significantly greater failure load (I3 = 67.3 ± 26.8 N) as compared to placebo (P3 = 37.9 ± 10.8 N) (p<0.01). (Figure 1) Failure stress was greater than placebo, 4.63 ± 1.8 MPa and 2.83 ± 1.8 MPa respectively (p<0.025); as was cross-sectional area, 12.1mm²± 2.9 and 8.9 ± 4.3 mm²respectively (p<0.05). The untreated group had a comparable meanfailure load (N3 = 64.0 ± 38.4 N) to the NSAID groups. The viscoelastic property of total creep was less in the NSAID treated group 1.71 ± 0.4 mm vs. 2.64 ± 0.7 mm for placebo (p<0.025) at three weeks of healing (Figure 2). The untreated group also had less total creep (N3 = 1.10 ± 0.20 mm) than the placebo group at three weeks. At six and 14 weeks these differences were no longer present.

Conclusions: NSAID treatment following ligament injury produces ligaments with similar high and low load properties as untreated ligaments. This work suggests that NSAIDs have no inhibitory effects on ligament healing. As NSAIDs are effective analgesics and will provide patients with pain relief following injury, this data supports their use as part of the treatment regimen following acute ligament injury.