Lower extremity extensor mechanism injuries are relatively infrequent; however, when they do occur, they require surgical intervention in a timely manner to prevent serious functional limitations. Generally, these tendon injuries are divided into quadriceps tendon and patellar tendon injuries. Quadriceps tendon injuries are more common and generally occur in older patients (>40 years old), while patellar tendon injuries occur more commonly in younger patients (<40 years old). Both types of injuries occur mainly in patients with preexisting tendon degenerative changes. Other risk factors include steroid use, chronic disease (renal failure, diabetes, rheumatologic disorders, connective tissue disorders), and repetitive knee injections. Primary surgical repair is the treatment of choice in the majority of cases of complete tendon rupture. More complex surgical procedures are necessary for chronic tendon rupture. Outcomes are often good in low-demand patients if treatment is performed in the acute setting. For higher-demand patients, return to pre-injury activity level is less predictable.
