Definition:

Tendinopathy of quadriceps tendon or the attachments of the infrapatellar tendon; the term ‘jumper’s knee’ implies functional stress overload due to jumping or increase in activity.

Pathophysiology:

Forces through one leg on landing from a jump can be up to 12 times body weight; for a 75 kg person = 900 kg of weight transmitted through the leg at peak force! Repetitive jumping (eccentric to concentric loading) eventually results in infrapatellar tendon microtears as damage exceeds body’s ability to repair itself → pain & loss of tensile strength → macroscopic tendon thickening → collagen degeneration → tendon rupture (severe cases).

Demographics

Incidence: estimated ~20% of jumping athletes Age: any age (more common 12-35 yrs)

Gender: bilateral female = male

unilateral: male > female (2:1) Genetics: one study noted a longer lower patellar pole associated with chronic patellar tendinopathy (Hyman, 2008) Risk factors: over training.

  • Poor jumping & landing technique/ biomechanics
  • Jumping sports (volleyball, basketball)
  • Inflexibility & weakness of hamstrings or quadriceps (also look at hip flexors)
  • Rapid increase in activity or intensity (10% rule = don’t increase training distance, intensity, or time more than 10% per week)
  • Court surface hardness or slope
  • Increased body weight & height
  • Over pronation &/or worn out foot wear may play a role

History

  • Anterior knee pain (achy or itching quality) below the patella (rarely may be above)
  • Pain is worse with excessive activity
  • Increased pain after prolonged sitting, relieved by straightening leg
  • History of positive risk factors (jumping activities) There are 4 main stages
    1. Pain only after activity, without functional
    2. Pain during and post activity, although satisfactory performance level in their sports or activity.
    3. Prolonged pain during or after activity, with increasing difficulty in performing at a satisfactory level.
    4. Complete tendon tear requiring surgical repair (note patellar displacement).

Inspection:        Potentially altered gait.

Swelling & inflammation are rare. Affected tendon may appear thicker.

Palpation:

Localized point tenderness over tendon

 

Motion:

Pain with compression of patellofemoral joint Hamstring or quadriceps tightness

Possible compensatory joint dysfunctions (foot, ankle, knee, hip, pelvis, low back)

Active range of motion weakness with squat, mild crepitus possible Possible pain with passive range of motion at end range of knee flexion stretch of infrapatellar tendon

Possible pain with resisted range of motion into extension or quadriceps weakness

Should not have ligament laxity.

Surgery (rarely required)

  • Indicated in stage 4 – arthroscopic repair has

shown good to excellent recovery as early as 6 weeks

Follow-up

Rehabilitation Program
  • Knee immobilization is contraindicated due to resulting stiffness & may lead to muscle or joint contracture, further prolonging condition
  • Stretch hip & knee flexors & extensors
  • Strengthen lower extremity with closed chain eccentric exercises (slow squat on decline board) – Jonsson, 2005, found eccentric quadriceps strengthening on a decline board superior to concentric strengthening in terms of pain, treatment satisfaction & return to play
  • Sport-specific proprioceptive training & plyometrics
Prevention/ Education
  • Proper footwear, consider orthotic use
  • If there is a co-existing patellar tracking problem consider knee brace with a patellar cut out
  • Consider change in activity type or lifestyle
  • Balance exercises (wobble board)
  • Palpable point tenderness is the best finding
  • Single leg stance or hop functional assessment
  • Excessive pelvic motion or abdominal (core) weakness affecting biomechanics

Jumper’s knee is strongly suggested when chondromalacia is negative Treatment

  • Ice after activity
  • Consider short-term anti-inflammatory use for pain reduction
  • Modify activities to avoid patellofemoral pressure
  • Mobilization & manipulation of the spine, pelvis, hip, knee, & foot to help optimize biomechanical function
  • TENS for short-term pain reduction
  • Ultrasound or phonophoresis (infusion of medication)
  • Extracorporeal Shock Wave Therapy (may show outcome of success similar to surgery

– Peers, 2003) – shock waves to treat chronic musculoskeletal conditions stimulates healing by moving injury back to an acute phase of healing. – BEST TREATMENT OPTION

Prognosis

  • Within ~3 week significant improvement is usually noted with conservative treatment of stage 1 or 2
  • Stage 3 may take longer & require long-term lifestyle & activity modification
  • With co-existing knee pathologies (instability, chondromalacia patellae, etc.) expect healing to be long & potentially lead to chronic knee issues
  • With co-existing knee pathologies (instability, chondromalacia patellae, etc.) expect healing to be long & potentially lead to chronic knee