Medial collateral ligament healing without treatment has been studied in a rabbit model. Complete midsubstance gaps were found to heal by distinct scar formation over time. This healing process was fast since the gap was bridged quickly; however, more subtle changes in appearance of the healing tissue continued for many months. The ligament "scar" was found to be structurally abnormal chemically and mechanically even at long-term followup. A plateau in its improvement suggests that the scar may never approach normal ligament characteristics (without treatment). A baseline of ligament healing by scar formation has been established.