Background: Arthroscopic anterior cruciate ligament (ACL) reconstruction with patellar tendon graft has been considered to be the gold standard treatment of anterior cruciate ligament injuries. Much morbidity could occur after this graft was harvested, such as the patellar tendon length change and anterior knee pain. Insall-Salvati ratio is one of the tools to determine the patella tendon length.
Objective: To study the patella tendon length change after arthroscopic ACL reconstruction with patellar tendon graft by using Insall-Salvati ratio.
Material and Method: Descriptive study was conducted. Patients who were diagnosed ACL injury and underwent arthroscopic ACL reconstruction with patellar tendon graft were included. All patients had standardized preoperative and postoperative lateral knee radiographs. The patellar tendon length, patellar height, Insall-Salvati ratio and Tegner Lysholm knee score were measured by the same person for all subjects at preoperative and 6 months postoperative period.
Results: In a series of 22 patients, the length of the patellar tendon lengthened by an average of 0.95 mm (6 mm shortening to 5 mm lengthening) or 1.82% and not statistically significant (p = 0.101). The Insall-Salvati ratio increased by 2.75% (16.32% shortening to 18.6% lengthening) which was also not statistically significant (p = 0.218). The Tegner Lysholm knee score was improved to 20.36 (5 to 45), which was statistically significant (p < 0.05). The amout of the Insall-Salvati ratio change was not related to Lysholm score (p = 0.571).
Conclusion: The present study indicated that there was no significant change of patellar tendon length after arthroscopic ACL reconstruction with patellar tendon graft. No correlations with postoperative Insall-Salvati ratio and Tegner Lysholm knee score, however, the clinical results was improved in all of the patients.

Keywords: Insall-Salvati ratio, Arthroscopic anterior cruciate ligament reconstruction, Patellar tendon graft, Patellar tendon
length, Patellar height, Tegner Lysholm knee score