Evaluation of chondrocyte death in canine osteochondral explants exposed to a 0.5% solution of bupivacaine.

OBJECTIVE

To evaluate chondrocyte death in canine articular cartilage exposed in vitro to bupivacaine with and without methylparaben and to compare viability for cartilage with intact or mechanically debrided surfaces.

SAMPLE POPULATION

Both glenohumeral joints from 10 adult canine cadavers.

PROCEDURES

10 osteochondral cores were harvested from each of the 20 humeral heads; synovium and 1 core from each joint were examined to verify joint health, and the other 9 cores were exposed to canine chondrocyte culture medium (CCCM), a 0.5% solution of bupivacaine, or 0.5% solution of bupivacaine with methylparaben for 5, 15, or 30 minutes.

RESULTS

For the superficial zone of surface-intact chondrocytes, bupivacaine with methylparaben caused a significantly higher percentage of chondrocyte death at 5 minutes (47.7%) than did bupivacaine (23.6%) or CCCM (25.4%). Bupivacaine (53.8%) and bupivacaine with methylparaben (62.5%) caused a significantly higher percentage of chondrocyte death at 30 minutes than did CCCM (20.0%). For the superficial zone of chondrocytes with debrided surfaces, bupivacaine with methylparaben caused a significantly higher percentage of chondrocyte death at 30 minutes (59%) than it did at 5 minutes (37.7%). Bupivacaine with methylparaben caused a significantly higher percentage of chondrocyte death at 30 minutes (59.0%) than did CCCM (28.9%). For middle and deep zones of chondrocytes, treatment solution and surface debridement had minimal effects on percentage of chondrocyte death.

CONCLUSIONS AND CLINICAL RELEVANCE

Bupivacaine and bupivacaine with methylparaben were cytotoxic to canine articular chondrocytes in vitro. Intra-articular administration of bupivacaine is not recommended for clinical use until additional studies are conducted.