Healing compared between bone to tendon and cartilage to tendon in a partial inferior patellectomy model in rabbits.

OBJECTIVE

Sports injuries around bone-tendon junctions are not uncommon. This study was designed to perform a quantitative evaluation on healing characteristics at the cartilage-to-tendon (C-T) and the bone-to-tendon (B-T) healing junction in a temporal and spatial manner.

DESIGN

Basic science study.

SETTINGS

University medical school.

ANIMALS

Thirty-two 18-week-old New Zealand white rabbits.

INTERVENTION

All rabbits underwent partial inferior patellectomy. The operated patella-patellar tendon (PPT) complex was harvested at 2, 4, 8, and 16 weeks postoperatively (n = 8 for each time point).

MAIN OUTCOME MEASURES

The fusion ratio (ie, the ratio of tissue integration calculated along the length of the healing junction interface at both C-T and B-T junction of sagittal plane of PPT complex).

RESULTS

The fusion ratio at the C-T interface was 69.5% and 85.9%, which was significantly greater as compared with 45.9% and 60.1% at the B-T interface at week 2 and week 4, respectively (P < 0.01 for both). Under polarized light microscope, a small amount of collagen fibers crossing the C-T junction was seen, but none were found at the B-T interface at week 2. At 4 weeks, there was a distinct fibrocartilage zone regenerated at the C-T junction, but there were only limited collagen fibers at the B-T junction. The difference in the fusion ratio, however, was diminished with healing over time between the C-T and B-T junctions at both week 8 (90.2% vs. 80.1%) and week 16 (93.1% vs. 85.3%) (both, P > 0.05).

CONCLUSION

These findings demonstrated that the C-T junction might have an earlier and faster healing potential as compared with that of the B-T repair. The earlier fusion of the C-T junction might provide earlier stability along the entire PPT healing interface that would form a basis for improved postoperative prognosis of PPT healing complex.