VIDEO: Understand anatomic factors to address patellofemoral instability, OA

ByElizabeth A. Arendt, MD

Fact checked byGina Brockenbrough, MA

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KOLOA, Hawaii — In this video from Orthopedics Today Hawaii, Elizabeth A. Arendt, MD, offered tips and tricks for the management of patellofemoral instability in patients with patellar dislocation and osteoarthritis.

Perspective from John P. Fulkerson, MD

“One has to have a good understanding of anatomic patella instability factors. There are many, and they are typically measured on imaging – both plain X-rays and MRI,” she said. “I believe that you have to better understand things like patella alta and the degree of the trochlear dysplasia. How crazy is your sulcus – what kind of shape it’s in – and how does the patella track through that sulcus?” Arendt added.

Perspective

John P. Fulkerson, MD

I will add that appropriate addition of tibial tubercle transfer (preferably anteromedial tibial tubercle osteotomy which unloads in the presence of distal and/or lateral patella articular damage or malalignment) is important to consider. Optimal decision-making is likely to rest on 3D imaging as it becomes more mainstream and since complex patellofemoral instability problems are almost impossible to understand adequately using 2D criteria. Tibial tubercle-trochlear groove (TT-TG) distance, as Dr. Arendt suggests early in her comments, is not very consistent and should not be the sole criteria for decision-making about whether to add osteotomy in patellofemoral surgery.

Overmedialization is a potential pitfall and can be avoided with careful preoperative planning. What's important is to advance a lateralized patella into the trochlear groove, very selectively and only when needed to assure stability. This is done preferably with 3D understanding of the lateralized patella entry point to the trochlea. This is much better than TT-TG. We must understand the patella's entry point to the trochlea in three dimensions to optimize decision-making.