Retropatellar Accessory Portals for Improved Access to the Patella; Anatomic Description and Evaluation of Safety

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Current arthroscopic techniques are limited in their ability to achieve the appropriate orientation necessary to address deep chondral defects of the patella. We describe novel retropatellar portals to offer improved access to critical areas of the retropatellar region for the treatment of chondral defects. A descriptive anatomic study was performed on 10 cadaveric knees. Novel retropatellar portals were created to access the undersurface of the patella, and the distance to adjacent neurovascular structures (common peroneal nerve (CPN) and infrapatellar branch of the saphenous nerve (IPBSN)) was assessed. Distances to these structures, in addition to bony landmarks (medial & lateral epicondyles and margins of the mid-patella), were recorded to describe the precise location of the portals for their safe use. Safe placement can confidently be established on the lateral aspect of the knee guided by palpation of bony landmarks. The lateral retropatellar portal was separated by the CPN by an average of 53.8 ± 7.2mm. Further, on the medial aspect of the knee, the IPBSN was an average distance of 15.8 ± 15.5 mm from the portal site. No nerves were transected or contacted in any specimens. The new retropatellar portals markedly improve visualization and achieve near perpendicular alignment of arthroscopic instruments to the posterior patella. We believe these portals are safe to use and thus clinically acceptable.