Patellar Tendinitis

Patellar tendinitis is inflammation or irritation of a tendon the thick fibrous cords that attach muscle to the bone of the patella, and injury to the tendon connecting your kneecap (patella) to your shinbone. The patellar tendon works with the muscles at the front of your thigh to extend your knee so that you can kick, run and jump. The patellar tendon works with the muscles at the front of your thigh to extend your knee so that you can kick, run and jump. The cause of tendonitis and tenosynovitis is often not known. They may be caused by strain, overuse, injury, or too much exercise. Tendonitis may also be related to a disease such as diabetes, rheumatoid arthritis, or infection. Patellar Tendonitis is usually curable within 6 weeks if treated appropriately with conservative treatment and resting of the affected area.

Other Names

  • Jumpers Knee
  • Patellar Tendinitis
  • Patellar Tendinopathy
  • Patellar Tendinosis
  • Patellar tendon pain

Pathophysiology

  • General
    • Represents a common overuse injury of the knee extensor mechanism
    • Can be seen acutely or chronically
    • Sports that involve rapid changes of direction, jumping, and running such as basketball and volleyball
    • The landing phase contributes more to injury than the take-off phase
  • Occurs due to chronic repetitive tendon overload
    • Microtrauma can lead to individual fibril degeneration due to stress across the tendon
    • May result in weakening of the tissue
    • Tension is greatest with increased knee flexion
  • Other proposed theories of pathogenesis
    • Vascular
    • Mechanical
    • Impingement–related
    • Nervous system
  • Histopathology
    • Initially thought to be inflammatory, now considered a degenerative condition (tendinosis or tendinopathy)
  • Patellar Apophysitis (Sinding-Larsen-Johansson Disease)
  • Tibial Tuberosity Apophysitis (Osgood Schalatters Disease)
  • Patellofemoral Pain Syndrome (PFPS)
  • Patellar Tendon
    • Extends distally from the inferior pole of the Patella to the Tibial Tubercle
    • Helps assist as part of the Knee Extensor Mechanism with the Quadriceps Muscle and Quadriceps Tendon
  • Area of pathology
    • Tends to occur at the inferior pole of the patella more commonly than tibial tuberosity
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Causes

  • Sports
    • Basketball
    • Volleyball
    • Ice skating
  • Intrinsic factors
    • Male are slightly more common than females[7]
    • Weight
    • Body Mass Index
    • Waist-to-hip ratio[8]
    • Leg-length difference
    • Arch height of the foot
    • Decreased quadriceps flexibility
    • Decreased hamstring flexibility
    • Quadriceps strength
    • Vertical jump performance
    • Patella alta[9]
    • Abnormal patellar tracking[10]
  • Extrinsic
    • Single sport athletes in basketball, volleyball or soccer at 4x greater risk[11]
  • Among volleyball players
    • The volume of training[3]
    • Training surface (concrete worse than wood)
    • Greater match exposure[12]

Differential Diagnosis

  • Fractures
    • Distal Femur Fracture
    • Patellar Fracture
    • Tibial Plateau Fracture
  • Dislocations & Subluxations
    • Patellar Dislocation (and subluxation)
    • Knee Dislocation
    • Proximal Tibiofibular Joint Dislocation
  • Muscle and Tendon Injuries
    • Quadriceps Contusion
    • Iliotibial Band Syndrome
    • Quadriceps Tendonitis
    • Patellar Tendonitis
    • Popliteus Tendinopathy
    • Extensor Mechanism Injury
      • Patellar Tendon Rupture
      • Quadriceps Tendon Rupture
      • Patellar Fracture
  • Ligament Pathology
    • ACL Injury
    • PCL Injury
    • MCL Injury
    • LCL Injury
    • Meniscal Pathology
    • Posterolateral Corner Injury
    • Multiligament Injury
  • Arthropathies
    • Knee Osteoarthritis
    • Septic Arthritis
    • Gout
  • Bursopathies
    • Prepatellar Bursitis
    • Pes Anserine Bursitis
    • MCL Bursitis
    • Infrapatellar Bursitis
  • Patellofemoral Pain Syndrome (PFPS)/ Anterior Knee Pain)
    • Chondromalacia Patellae
    • Patellofemoral Osteoarthritis
    • Osteochondral Defect Knee
    • Plica Syndrome
    • Infrapatellar Fat Pad Impingement
    • Patellar Instability
  • Neuropathies
    • Saphenous Nerve Entrapment
  • Other
    • Bakers Cyst
    • Patellar Contusion
  • Pediatric Considerations
    • Patellar Apophysitis (Sinding-Larsen-Johansson Disease)
    • Patellar Pole Avulsion Fracture
    • Tibial Tubercle Avulsion Fracture
    • Tibial Tuberosity Apophysitis (Osgood Schalatters Disease)

Symptoms

  • Pain and tenderness around your patellar tendon.
  • Swelling.
  • Pain with jumping, running, or walking.
  • Pain when bending or straightening the leg.
  • Tenderness behind the lower part of the kneecap.

Diagnosis

  • History
    • The onset of pain is typically insidious
    • Patients will complain of knee pain just below the patella
    • Initially, pain is only after activity, then eventually during activity, and potentially all the time
    • Movie Theatre Sign: The patient can endorse pain after prolonged periods of sitting, for example in a movie theatre
  • Physical Exam: Physical Exam Knee
    • Swelling over the tendon may or may not be present
    • Tenderness in the inferior patella pole, along the tendon or at the tibial insertion
    • Pain with the resisted extension of the knee or with maximal stretching of the quadriceps
  • Special Tests
    • Bassets Sign: Tenderness of inferior patellar pole in extension but not inflection
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Radiographs

  • Standard Radiographs Knee
    • Radiographs are a common screening tool
    • Typically normal

Ultrasound

  • Ultrasound can be used to evaluate tendon integrity
  • Findings
    • Hypoechoic areas
    • Thickened tendon
    • Neovascularization (chronic)

MRI

  • Indications
    • Chronic cases
    • Surgical planning
  • Findings
    • Tendon thickening
    • Increased signal on T1, T2
    • Sometimes loss of posterior border of fat pad

Blazina Classification System

  • Phase I: pain after activity only
  • Phase II: pain during and after activity
  • Phase III: persistent pain with or without activities, deterioration of performance

Treatment

Nonoperative

  • General
    • Temporary discontinuation of offending sport
    • Relative rest
    • Ice Therapy
    • Avoid complete immobilization to prevent atrophy
  • Oral Medications[13]
    • NSAIDS are likely useful in the short term[14]
    • Acetaminophen
    • Opioids
  • Topical Nitroglycerin
    • No significant difference between topical NO and placebo + eccentric training at 24 weeks, with both groups showing improvement
  • Physical Therapy
    • Avoidance of jumping activities with stretching after physical activity may help in early disease
    • Individuals performing eccentric exercises improved significantly compared with those undergoing a concentric exercise program
    • RCT: Progressive tendon-loading exercises (PTLE) resulted in a significantly better clinical outcome after 24 weeks than eccentric exercise therapy (EET)
  • Consider Patellar Counterforce Strap
    • May decrease patellar tendon strain by altering the angle between patella and patella tendon
    • The overall evidence is weakly favorable
    • There are no high-quality level 1 studies
  • Corticosteroid Injection
    • Not generally recommended due to the risk of rupture
    • Under ultrasound guidance, some benefit over placebo at 4 weeks for pressure, and walking pain
    • At 6 months, was inferior to eccentric training and heavy slow resistance training
  • Aprotinin Injection
    • When compared to corticosteroids and placebo, aprotinin had 72% good/excellent results compared with 59% in the CSI group and 28% in the placebo group
    • High risk of side effects including anaphylaxis, bovine spongiform encephalopathy
  • Sclerosing Injection
    • Polidocanol injection showed significant improvement in VISCA score at 4 months
    • Polidocanol was inferior to arthroscopy for pain, satisfaction, and return to sport
  • Platelet Rich Plasma
  • Extracorporeal Shock Wave Therapy (ESWT)
    • No difference between ESWT and surgical tenotomy at 22-26 months
    • Compared to a control arm of NSAIDS, physical therapy, and patellar strap, ESWT was superior at 2- and 3-years of follow-up
  • Consider Needle Tenotomy
  • Consider Orthobiologics
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Operative

  • Indications
    • Refractory cases
  • Surgery
    • Open debridement
    • Arthroscopic debridement