Wiberg Patellar Type Impact on Outcomes and Survival

The Wiberg classification describes the shape of the kneecap based on the relative size and angle of its inner and outer surfaces seen on a specific view. Type I has roughly equal inner and outer surfaces; Type II has a smaller, more upright inner surface (the most common); and Type III has a very small or convex inner surface. Surgeons use this anatomical descriptor when planning kneecap procedures and when interpreting cartilage outcomes.

In this midterm study, the Wiberg kneecap type did not significantly influence patient-reported outcomes or graft survival after cell-based cartilage repair for kneecap cartilage defects. That means a less favorable kneecap shape is not, by itself, a reason to avoid cell-based repair such as MACI. Other factors — defect size, alignment, lesion location, and kneecap tracking — remain more important predictors of success.

For cartilage defects behind the kneecap, the main biologic repair options are MACI (cartilage cells grown from your own tissue and re-implanted), osteochondral allograft (donor cartilage and bone), and DeNovo NT (small fragments of donor juvenile cartilage). The choice depends on the size, depth, and location of the defect, the patient's age, and whether bony correction or realignment — such as a tibial tubercle osteotomy — is also needed.