Patellar tendinopathy is a source of pain in the front of the knee and is characterized by pain localized to the lower pole of the patella.  Pain is aggravated by loading and with increased demands on the knee extensor tissue, particularly during activities where the patella stores and releases energy Tendon  .
Patellar tendinopathy occurs primarily in relatively young (15-30 years) athletes, especially men who participate in sports such as basketball, volleyball, field jumping, tennis, and soccer, where repetitive loading of the patellar tendon is required . the prevalence of this condition Among elite volleyball and basketball players, this percentage has exceeded 40%.  While certain intrinsic risk factors for patellar tendinopathy have been identified, such as weight for sex and body mass index, the most important risk factor appears to be training load (i.e., extrinsic risk factor). 
Clinically Relevant Anatomy
Cross-section of the tendon. Collagen fibers make up a pale pink background. Fine wire separates fiber bundles. Black dots are tendon cell nuclei. 
The quadriceps is attached to the lower pole of the patella via the quadriceps tendon through the femur (i.e., the patella). The patellar tendon then connects the base of the patella to the tibial tuberosity. force generated by the quadriceps The patella acts as a pulley leading to knee extension 
A healthy tendon is mainly composed of closely packed parallel collagen fibers (86%) . Collagen is mainly type I. Other components of the tendon matrix are elastin (2%), proteoglycans (1–5%), and inorganic components (0.2%). collagen in tendon Proteoglycan components Decorin and Aggrecan bind to collagen fibers at specific locations
Tenocytes are tendon-specific fibroblasts that produce collagen molecules that aggregate together to form collagen fibers. Fibril bundles are organized into fibers with elongated tenocytes packed tightly between them. Cells communicate with each other through gap junctions This signal enables them to detect and respond to mechanical loads .
The blood vessels run parallel to the collagen fibers within the tendon, with some branches anastomosing transversely. The inner tendon is thought to have no innervation, but adjacent to the tendon are nerve endings, and the Golgi tendon organ exists at the junction between tendon and muscle.
Cook and Purdam described a continuum of tendon pathology with three distinct stages :
- Reactive tendinopathy
- Tendon disrepair
- Degenerative tendinopathy
Load is considered the primary stimulus that drives tendon health forward and backward along the continuum.
Non-inflammatory proliferative responses in cells and stroma occur with acute stretch or compression overload. During this phase, tenocytes proliferate and protein production increases.  This causes a short-term adaptation to the tendon as it thickens and eventually reduces Relieves stress by increasing cross-sectional area or allowing for accommodation in compression. This differs from the normal tendon’s response to loading, which usually occurs through tendon sclerosis. Clinical reactive tendinopathy occurs during unaccustomed physical activity. less common after a direct hit Like falling directly onto the patellar tendon.
Attempts at tendon healing continued after the reactive phase, but with greater matrix disruption. The number of cells present in the stroma increases, resulting in increased protein production (proteoglycans and collagen). Increased proteoglycans lead to separation and collagen breakdown. Vascularity and neuronal growth may be increased. Clinically, this phase of pathology is seen in chronically overloaded tendons and occurs at all ages and loading settings.
There are areas of cell death due to apoptotic trauma or depletion of tenocytes. There is a large area of matrix disordered and filled with vascular matrix breakdown products and a small amount of collagen. The reversibility of pathological changes at this stage is very small. This stage is Mainly seen in the elderly.
Patellar tendinopathy is one of many potential diagnoses in patients with anterior knee pain. There are two distinct clinical features :
- Pain limited to the inferior pole of the patella
- Load-related pain increases with the demands on the knee extensors, especially during activities that store and release energy in the patellar tendon.
Patients may complain of pain when sitting for long periods of time, squatting, and climbing stairs, but these complaints are characteristic of other conditions, such as patellofemoral pain. Pain is rarely felt at rest. Pain that begins immediately upon loading and usually stops almost immediately upon loading delete. Repeated weight bearing may improve pain. An important feature of tendinopathy is that they are dose-dependent pain increases with the magnitude or rate of loading on the tendon . The practical application of this in pain examination should increase When going from shallow squats to deep squats or from small jumps to big jumps.
Weighted activities are primarily weight-bearing activities, such as when walking down stairs or performing incline squats.
See previous section for dose-dependent pain. Insufficient energy storage activity can be assessed clinically by observing jumps and jumps. Individuals with a history of patellar tendinopathy may use a straight-knee vertical jump landing strategy .
Examination of the entire lower extremity is necessary to identify associated deficiencies in the hip-knee and ankle/foot regions. Atrophy, decreased strength, poor foot posture, quadriceps and hamstring inflexibility, and decreased ankle dorsiflexion are associated with patellar tendinopathy and should has also been evaluated .
Imaging of the patellar tendon does not confirm patellar tendon pain because the pathology observed by ultrasound imaging may be present in asymptomatic individuals .
- Pain provocation (Visual Analog Scale or Victorian Institute for Movement Assessment-patella )
- Tendon swelling
- Return to activity
Non-steroidal anti-inflammatory drugs
The use of nonsteroidal anti-inflammatory drugs (NSAID’s) in the acute and chronic phases of tendinopathy remains controversial. NSAIDs have been reported to hinder soft tissue healing. While the pain may be lessened, they have a negative effect on the tendon Repair . In reactive tendinopathy, this may be the preferred effect, as this may inhibit proteins that cause tendon swelling .
Corticosteroids are used to reduce pain, but also reduce cell proliferation and protein production, and are therefore useful in reactive tendinopathy. Repeated administration of peritendonal corticosteroids at 7 and 21 days after tendon injection has been shown to reduce tendon diameter .
Tendon surgery for chronic pain has produced mixed results, with 50-80% of athletes able to return to their previous level of activity . Surgical outcomes in non-active populations are inferior to those in active populations . For all patients who fail, surgery is considered a reasonable option conservative intervention.
- ↑ Aicale R, Oliviero A, Maffulli N. Management of Achilles and patellar tendinopathy: what we know, what we can do. Journal of Foot and Ankle Research. 2020 Dec;13(1):1-0.
- ↑ Jump up to:2.0 2.1 2.2 2.3 Malliaras P, Cook J, Purdam C, Rio E. Patellar Tendinopathy: Clinical Diagnosis, Load Management, and Advice for Challenging Case Presentations. The Journal of orthopaedic and sports physical therapy. 2015 Sep:1-33. (level of evidence: 2a)
- ↑ Breda SJ, Oei EH, Zwerver J, Visser E, Waarsing E, Krestin GP, de Vos RJ. Effectiveness of progressive tendon-loading exercise therapy in patients with patellar tendinopathy: a randomised clinical trial. British journal of sports medicine. 2021 May 1;55(9):501-9.
- ↑ Lian ØB, Engebretsen L, Bahr R. Prevalence of jumper’s knee among elite athletes from different sports a cross-sectional study. The American journal of sports medicine. 2005 Apr 1;33(4):561-7. level of evidence 4
- ↑ Maffulli N, Oliva F, Loppini M, Aicale R, Spiezia F, King JB. The Royal London Hospital Test for the clinical diagnosis of patellar tendinopathy. Muscles Ligaments Tendons J. 2017;7(2):315-22.
- ↑ Maciel Rabello L, Zwerver J, Stewart RE, van den Akker-Scheek I, Brink MS. Patellar tendon structure responds to load over a 7-week preseason in elite male volleyball players. Scand J Med Sci Sports. 2019;29(7):992-9.
- ↑ Kumc.edu. (2017). JayDoc HistoWeb. [online] Available at: http://www.kumc.edu/instruction/medicine/anatomy/histoweb/ [Accessed 16 Sep. 2017].
- ↑ Palastanga N, Field D, Soames R. Anatomy and human movement: structure and function. Elsevier Health Sciences; 2012.
- ↑ Lin TW, Cardenas L, Soslowsky LJ. Biomechanics of tendon injury and repair. Journal of biomechanics. 2004 Jun 30;37(6):865-77. level of evidence 2a
- ↑ Zhang G, Ezura Y, Chervoneva I, Robinson PS, Beason DP, Carine ET, Soslowsky LJ, Iozzo RV, Birk DE. Decorin regulates assembly of collagen fibrils and acquisition of biomechanical properties during tendon development. Journal of cellular biochemistry. 2006 Aug 15;98(6):1436-49.
- ↑ McNeilly CM, Banes AJ, Benjamin M, Ralphs JR. Tendon cells in vivo form a three dimensional network of cell processes linked by gap junctions. Journal of anatomy. 1996 Dec;189(Pt 3):593
- ↑ Cook JL, Purdam CR. Is tendon pathology a continuum? A pathology model to explain the clinical presentation of load-induced tendinopathy. British journal of sports medicine. 2009 Jun 1;43(6):409-16.
- ↑ Knapik JJ, Pope R. Achilles Tendinopathy: Pathophysiology, Epidemiology, Diagnosis, Treatment, Prevention, and Screening. J Spec Oper Med. 2020 Spring;20(1):125-40.
- ↑ Kountouris A, Cook J. Rehabilitation of Achilles and patellar tendinopathies. Best practice & research clinical rheumatology. 2007 Apr 30;21(2):295-316. level of evidence 4
- ↑ Bisseling RW, Hof AL, Bredeweg SW, Zwerver J, Mulder T. Relationship between landing strategy and patellar tendinopathy in volleyball. British journal of sports medicine. 2007 Jul 1;41(7):e8-. level of evidence 3b
- ↑ Malliaras P, Cook J, Ptasznik R, Thomas S. Prospective study of change in patellar tendon abnormality on imaging and pain over a volleyball season. British journal of sports medicine. 2006 Mar 1;40(3):272-4.
- ↑ Visentini PJ, Khan KM, Cook JL, Kiss ZS, Harcourt PR, Wark JD, Victorian Institute of Sport Tendon Study Group. The VISA score: an index of severity of symptoms in patients with jumper’s knee (patellar tendinosis). Journal of Science and Medicine in Sport. 1998 Jan 31;1(1):22-8.
- ↑ Ferry ST, Dahners LE, Afshari HM, Weinhold PS. The effects of common anti-inflammatory drugs on the healing rat patellar tendon. The American journal of sports medicine. 2007 Aug 1;35(8):1326-33.
- ↑ Riley GP, Cox M, Harrall RL, Clements S, Hazleman BL. Inhibition of tendon cell proliferation and matrix glycosaminoglycan synthesis by non-steroidal anti-inflammatory drugs in vitro. Journal of Hand Surgery (British and European Volume). 2001 Jun 1;26(3):224-8.
- ↑ Fredberg U, Bolvig L, Pfeiffer‐Jensen M, Clemmensen D, Jakobsen BW, Stengaard‐Pedersen K. Ultrasonography as a tool for diagnosis, guidance of local steroid injection and, together with pressure algometry, monitoring of the treatment of athletes with chronic jumper’s knee and Achilles tendinitis: a randomized, double‐blind, placebo‐controlled study. Scandinavian journal of rheumatology. 2004 Mar 1;33(2):94-101. level of evidence 1b
- ↑ Tallon C, Coleman BD, Khan KM, Maffulli N. Outcome of surgery for chronic Achilles tendinopathy a critical review. The American Journal of Sports Medicine. 2001 May 1;29(3):315-20.
- ↑ Maffulli N, Testa V, Capasso G, Oliva F, Sullo A, Benazzo F, Regine R, King JB. Surgery for chronic Achilles tendinopathy yields worse results in nonathletic patients. Clinical Journal of Sport Medicine. 2006 Mar 1;16(2):123-8.
- ↑ Simpson M, Smith T. Quadriceps tendinopathy-a forgotten pathology for physiotherapists? A systematic review of the current evidence-base. Phys Ther Rev. 2011;16(6):455-61. (level of evidence: 2a)
- ↑ Naugle KM, Fillingim RB, Riley JL. A meta-analytic review of the hypoalgesic effects of exercise. The Journal of pain. 2012;13(12):1139-50. (level of evidence: 2a)
- ↑ van Rijn D, van den Akker-Scheek I, Steunebrink M, Diercks RL, Zwerver J, van der Worp H. Comparison of the Effect of 5 Different Treatment Options for Managing Patellar Tendinopathy: A Secondary Analysis. Clin J Sport Med. 2019;29(3):181-7.
- ↑ Jump up to:26.0 26.1 26.2 Malliaras P, Barton CJ, Reeves ND, Langberg H. Achilles and patellar tendinopathy loading programmes. Sports Med. 2013;43(4):267-86. (level of evidence: 2a)
- ↑ Rio E, Kidgell D, Moseley GL, Gaida J, Docking S, Purdam C, Cook J. Tendon neuroplastic training: changing the way we think about tendon rehabilitation: a narrative review. Br J Sports Med. 2015 Sep 25:bjsports-2015. Available from: http://bjsm.bmj.com/content/50/4/209 [Accessed 25 Feb 2017]
- ↑ Kertzman, P., Lenza, M., Pedrinelli, A., & Ejnisman, B.(2015). Shockwave treatment for musculoskeletal diseases and bone consolidation: qualitative analysis of the literature. Revista Brasileira de Ortopedia, 50(1), 3–8. http://doi.org/10.1016/j.rboe.2015.01.003 (level of evidence: 1a)
- ↑ Abat, F., Sánchez-Sánchez, J. L., Martín-Nogueras, A. M., Calvo-Arenillas, J. I., Yajeya, J., Méndez-Sánchez, R., … Gelber, P. E. (2016). Randomized controlled trial comparing the effectiveness of the ultrasound- guided galvanic electrolysis technique (USGET) versus conventional electro- physiotherapeutic treatment on patellar tendinopathy. Journal of Experimental Orthopaedics, 3, 34. http://doi.org/10.1186/s40634-016-0070-4 (level of evidence: 1b)
- ↑ The Knee Resource. Spanish Squats – Isometric Exercise for Patellar Tendinopathy. Available from: https://youtu.be/mik90mAS6fU [last accessed 01/03/2018]
- ↑ The Knee Resource. Patellar Tendinopathy Rehab – Isotonic Exercises. Available from: https://youtu.be/g0XPFL1IwEc [last accessed 01/03/2018]
- ↑ The Knee Resource. Patellar Tendinopathy Rehab – Energy Storage Exercises. Available from: https://youtu.be/ppBl9L-OlH4 [last accessed 01/03/2018]
- ↑ Patellar Tendinopathy Rehab – Kinetic Chain Strengthening Exercise. Available from: https://youtu.be/t1blThXvLIk [last accessed 01/03/2018]