In the medial parapatellar approach for a total knee arthroplasty (TKA), the proximal arthrotomy is designed to pass directly through which specific anatomical structure?

Explanation:
The correct option is a. The standard medial parapatellar approach (often attributed to von Langenbeck and popularized by Insall) involves a proximal incision that splits the medial third of the quadriceps tendon. It then curves distally around the medial border of the patella and continues along the medial border of the patellar tendon down to the tibial tubercle. Leaving a robust cuff of tendon medially allows for strong, watertight closure and is critical for preventing postoperative patellar maltracking or subluxation. Reference: Scott WN. Insall & Scott Surgery of the Knee.