Basic Science
Core concepts
Know bone healing, tendon and ligament healing, articular cartilage structure, graft biology, suture and implant mechanics, and infection control. Primary bone healing occurs with rigid compression and direct osteonal remodeling; secondary healing involves callus. Tendon-to-bone healing passes through inflammatory, proliferative, and remodeling phases and is weaker than native insertion for months. Articular cartilage is avascular hyaline cartilage with poor intrinsic healing; fibrocartilage repair is biomechanically inferior. Allografts carry disease transmission and immunologic considerations, while autografts add donor-site morbidity. Understand suture configuration, anchor pullout, stress shielding, and the biology of augmentation.
Traps
Do not assume a tendon graft is strongest immediately after harvest; graft incorporation weakens before strengthening. Cancellous bone heals faster than cortical bone. A steroid injection may relieve pain but can impair tendon healing and increase infection risk if surgery follows too soon. Antibiotic prophylaxis is not a substitute for sterile technique. In cartilage questions, distinguish repair fibrocartilage from hyaline restoration.
Worked example
A young athlete needs an ACL reconstruction. Rule of thumb: bone-patellar tendon-bone autograft offers reliable bone-to-bone healing but risks anterior knee pain; hamstring autograft avoids that but has slower tendon-to-bone incorporation and hamstring weakness. Graft choice should match sport, anatomy, and rehabilitation priorities rather than a single universal recommendation.