Robert A. Christian, B.A., William H. Rossy, M.D., and Orrin H. Sherman, M.D.
Patellar tendinopathy (PT) is a clinical and chronic overuse condition of unknown pathogenesis and etiology marked by anterior knee pain typically manifested at the inferior pole of the patella. PT has been referred to as “jumper’s knee” since it is particularly common among populations of jumping athletes, such as basketball and volleyball players. Due to its common refractory response to conservative treatment, a variety of new treatments have emerged recently that include dry-needling, sclerosing injections, platelet-rich plasma therapy, arthroscopic surgical procedures, surgical
resection of the inferior patellar pole, extracorporeal shock wave treatment, and hyperthermia thermotherapy. Since PT has an unknown pathogenesis and etiology, PT treatment is more a result of physician experience than evidence-based science. This review will summarize the current literature on this topic, identify current research efforts aimed to understand the pathological changes in abnormal tendons, provide exposure to the emerging treatment techniques, and provide suggested direction for future research.
Patellar tendinopathy (PT) describes a clinical condition characterized by activity-related anterior knee pain associated with focal patellar tendon tenderness localized to the inferior pole of the patella.1,2 PT pain can also manifest at the distal insertion of the patellar tendon over the anterior tibial tuberosity. A challenge to patients and physicians alike, PT is a chronic and degenerative overuse condition triggered by repetitive microtrauma. Mechanical overload of the tendon is commonly cited as a key component with many other contributing extrinsic and intrinsic factors.4 Due to the uncertainty surrounding PT, the use of correct terminology is important when describing
the condition. As an overuse injury, PT should not be confused with patellar tendonitis, which is an inflammatory discomfort of the patellar tendon. The term “tendonitis” implies an inflammatory nature to the injury, which is not present in PT. “Patellar tendinosis” is the histopathological term to describe the degenerative presentation characteristic of an
overuse injury. A tissue biopsy is needed in order to describe patellar tendon pain as either “tendonitis” or “tendinosis.”
For these reasons, “patellar tendinopathy” has been adopted as the correct clinical term for overuse conditions of the patella tendon.1,4 Patellar tendinopathy is a common clinical presentation especially in athletic populations. It is particularly prevalent among elite jumping athletes, such as basketball and volleyball players with rates of 31.9% and 44.6%, respectively.5 Due to this high prevalence among jumping athletes, PT has historically been labeled as “jumper’s knee.”6 Since PT-related pain typically persists for 3 years and has been reported to persist for greater than 15 years, athletes developing PT symptoms are often forced to deal with chronic pain, which can reduce training, or even prematurely end their careers.5,2 Due to its debilitating effects, understanding and characterizing the symptoms of PT are key for patients. PT does not have an evidence-based, preferred choice for treatment. Conservative treatment of symptomatic PT focuses on rest, physical therapy, non-steroidal anti-inflammatory drugs (NSAIDs), and eccentric muscle training.7-9 In cases that are non-responsive to these modalities, both patients and physicians are left searching for alternatives.
Treatment of recurrent PT varies widely and can be broadly grouped into the following categories: exercise training, injection-basedtreatments, surgical procedures, and other therapies. Due to its unknown pathogenesis and etiology, treatment is often based on physician experience, exposure, and comfort with a specific treatment modalities. These factors have made the treatment and management of PT resemble more of an art than a science.8 The goal of this review is to identify recent research effors aimed at addressing PT in order to best inform physicians of the currently available treatment modalities. We will also discuss potential future areas of research with regard to PT.