Question

Do tendons regenerate easily? Does cartilage regenerate easily? Why or why not?

Answer 1

No, and no.

Explanation:

Tendon and ligament (T/L) are dense connective tissues connecting bone to muscle and bone to bone, respectively. At present, injuries to these tissues are treated by surgical repair and/or conservative approaches, including biophysical modalities such as physical rehabilitation and cryotherapy.

T/L injuries remain a persistent clinical challenge. Unfortunately, current treatment strategies fail to restore the functional, structural, and biochemical properties of repaired T/L to those of native tissue.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4041869/

Cartilage repair and regeneration is treatment for an otherwise healthy knee, but not for knees affected by osteoarthritis, a condition that causes natural cartilage deterioration from aging.

After cartilage repair, you will be on crutches for six to eight weeks. It takes several months to make a full recovery. Some patients require a continuous passive motion machine (CPM), a device that is used to gently flex and extend the knee, after surgery.
https://www.ucsfhealth.org/treatments/cartilage_repair/