J. Grant (Ann Arbor, US)
University of Michigan Orthopaedic SurgeryPresenter Of 1 Presentation
16.4.5 - Does Patellar Morphology Matter When Matching Osteochondral Allografts for Osteochondral Defects of the Central Ridge of the Patella?
Abstract
Purpose
To determine if differences in patellar surface morphology (e.g., Wiberg classification) play a role in the ability of donor patellar osteochondral allografts to acceptably (<1mm deviation) match the native patellar surface for osteochondral defects involving the patellar central ridge.
Methods and Materials
Each of twenty (10 Wiberg I and 10 Wiberg II/III) fresh frozen recipient patellae were size-matched (within 2mm tibial width) with a Wiberg I and Wiberg II/III donor patella. A 16mm diameter osteochondral “defect” centered on the central ridge of the recipient patella was created (Fig. 1A). Within each patellar trio, a randomly ordered donor Wiberg I or Wiberg II/III patellar plug was harvested, transplanted, scanned with nano-CT, digitally reconstructed, and processed in DragonFly to determine circumferential step-off heights between the native and donor surfaces, percent of the circumference unacceptably proud (>1mm), and unacceptably sunken (>1mm) (Fig. 1B-D). The process was then repeated for the other allograft plug. Paired t-tests and one-way ANOVAs with Sidak comparisons were used (α = 0.05). Calculated sample size = 7/group.
Results
There was no significant difference in step-off heights between matched and unmatched Wiberg plugs. When analyzing by quadrant, the step-off heights of the superior and inferior quadrants were significantly different, but not clinically relevant, across all patellas and Wiberg I recipients. The inferior quadrant of Wiberg I recipient patellas demonstrated a significant, but not clinically relevant, difference between matched and unmatched Wiberg donors (Table 1). No significant differences between matched and unmatched donors for the percent of circumference unacceptably proud. Difference of <4% between groups in percent of circumference unacceptably sunken (lateral quadrant).
Conclusion
Differences in Wiberg classification did not lead to differences in step-off heights circumferentially, or by quadrant. These findings suggest patellar surface morphology doesn’t play a role in matching donor allografts for patellar osteochondral defects.