Sat., 10/10/09 Basic Sci./Injury Prevent./Spine, Paper #68, 10:39 am OTA-2009
Minimally Invasive Plate Osteosynthesis: Advanced Early Fracture Healing in a Sheep Trauma Model
Martin E. Wullschleger, MD1 (7-Research Grant from AO Foundation);
Roland Steck, PhD1 (n);John Webster1 (n); Kathleen Wilson2 (n);Keita Ito, PhD3 (n);
Michael A. Schuetz, PhD1 (n);
1Queensland University of Technology, Institute of Health and Biomedical Innovation,
Brisbane, Queensland, Australia;
2The Prince Charles Hospital, Biological Research Facility, Brisbane, Queensland, Australia;
3Eindhoven University of Technology, Orthopaedic Biomechanics Section,
Eindhoven, The Netherlands
Purpose: Minimally invasive plate osteosynthesis (MIPO) has become a clinically accepted method with good results, when compared to the conventional open surgical approach (open reduction and internal fixation [ORIF]). However, while MIPO offers some advantages over ORIF, it also has some significant drawbacks, such as a more demanding surgical technique and increased radiation exposure. No experimental study to date showed a difference between the healing outcomes in fractures treated with the 2 surgical approaches. Therefore, we developed a novel, standardized severe trauma model in sheep, to examine the effect of the 2 surgical approaches on soft-tissue and fracture healing.
Methods: 24 sheep underwent severe soft-tissue damage and a multifragmentary distal femur fracture. The fractures were initially stabilized with an external fixator. After 5 days of soft-tissue recovery, internal fixation with a 4.5-mm narrow locking compression plate was applied, randomized either by MIPO or ORIF. Within the first 14 days, the soft-tissue damage was monitored by daily serum blood tests for creatine kinase (CK). The sheep were sacrificed in 2 groups after 4 and 8 weeks. CT scans were performed to determine callus volumes and mechanical testing to determine callus stiffness. The results were analyzed statistically with analysis of variance test.
Results: Soft-tissue monitoring showed significantly higher (P = 0.007) CK values in the ORIF group (1028.9 ± 827.0 U/L) compared to MIPO (286.4 ± 259.7 U/L). After 4 weeks, the torsional stiffness was significantly higher (P = 0.018) in the MIPO group (30.1 ± 10.6% of the intact contralateral femur) compared to the ORIF group (9.8 ± 12.4%). The mineralized callus volumes in the ORIF group (19141 ± 8511 mm3) tended to be higher (P = 0.43) than those of the MIPO group (15596 ± 6194 mm3), but were not statistically significant.
Conclusion: This study shows that surgical approach does influence fracture healing. Fractures treated with the MIPO technique had superior mechanical properties, despite smaller fracture callus. The open approach appeared to create more damage and led to the formation of a bigger callus. However, this size difference did not translate into superior mechanical properties. Clinically, these results indicate that despite the challenges involved with the MIPO technique, the outcome is at least as good as with the proven ORIF technique, with potential advantages during the early stages of healing.
• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant