Final answer:
The close packed position of the tibiofemoral (knee) joint is when the knee is fully extended, with slight medial rotation of the femur relative to the tibia, providing maximal stability and weight-bearing support.
Step-by-step explanation:
The close packed position of the tibiofemoral (knee) joint is achieved when the knee is in full extension. This position is considered the most stable for the knee joint, as it involves a slight medial rotation of the femur in relation to the tibia, allowing the ligaments to align and lock the joint into place. This locking mechanism provides maximal bony, weight-bearing support and stability, with the lateral and medial tibiofemoral joints articulating in such a way that the femoral condyles securely fit over the tibial condyles.
Moreover, the muscular and ligamentous structures surrounding the knee are at their maximal tension in this position, further enhancing stability. For example, the popliteus muscle performs a slight lateral rotation of the femur to initiate knee flexion, effectively "unlocking" the knee from its close packed position. Conversely, the reverse action of medial rotation secures the knee joint when the femur comes back into full extension.