With childhood obesity becoming ever more prominent leading to potential medical issues (ex, Cholelithiasis, Eating Disorders) it is wonderful to encourage all of our kids to be more active, but activity and sports have their own potential issues as well.  Previously, we have discussed sport-related, overuse injuries like Little League Shoulder and Osgood Schlatter’s Disease as well as common orthopaedic injuries like Supracondylar Fractures and Shoulder Dislocations.  Let us take a moment to digest a tasty Morsel on another common extremity complaint: Patellofemoral Pain Syndrome.

Patellofemoral Pain Syndrome: Basics

• The knee is bears a significant load during all activities.
• The patella facilitates force of knee extension. [Houghton, 2006]
• The patella also protects the patellar tendon from friction.

• Patellofemoral Pain Syndrome is one of the most common causes of anterior knee pain in the primary care arena. [Yin, 2016; Pengel, 2014; Houghton, 2006]
• Cause is multifactorial and varies between individuals. [Finlayson, 2014; Houghton, 2006]
  • Patellar malaignment
    • Larger Q angles associated with increased static patellofemoral joint stress.
    • Quadricep weakness (especially vestus medialis) also contributes to improper tracking of patella.
  • Mechanical overload of joint
    • Excessively jumping, running, etc.
    • Additionally, hip muscle weakness can increase load on the knee (the hip muscles can absorb up to 25% of the load that occurs during landing).
  • Decreased flexibility.
    • Inflexible muscles/tendons are less able to absorb eccentric loads .
    • Quadriceps, hamstings, hip flexors, gastrocnemius, and other soft tissues of the lower extremities all influence the patellofemoral joint.
  • Regional inflammatory changes.

• Epidemiology:
  • Affects females > males [Stracciolini, 2014; Houghton, 2006]
  • More commonly seen in adolescents. [Pengel, 2014]
  • May be related to activity, but also seen without specific activity.
  • Can be unilateral or bilateral.

Patellofemoral Pain Syndrome: Presentation

• Typically have poorly localized complaint of knee pain (“Knee Grab Sign“). [Pengel, 2014]
  • Dull and achy pain during and after activity. [Houghton, 2006]
  • Worse with weight bearing sports, squatting, or climbing stairs.
  • Also exacerbated upon standing after sitting for awhile.
• Patient may report a sensation of “giving way,” but there is no joint instability.
  • Occurs with ascending or descending stairs or an incline.
  • Meniscal / ligamentous injury leads to instability and apprehension with pivoting or twisting movements.
• On exam may have tenderness over:
  • Medial and/or lateral patellar facets
  • Superior and inferior poles of the patella
• Pain over the physes or joint line is NOT normal for patellofemoral pain. [Houghton, 2006]

Patellofemoral Pain Syndrome: DDx

• Always consider the following:
  • Patellar Instability / Subluxation / Dislocation
  • Osgood-Schlatter’s Disease
  • Osteochondritis Dissecans
    • Idiopathic lesion of the bone and cartilage
    • Leads to bone necrosis
    • Can lead to separation of the articular cartilage!
  • Referred Pain
    • SCFE
    • Legg Calve Perthes
  • Oncologic Process
    • Osteochondroma
    • Ewing’s Sarcoma
    • Osteosarcoma
    • Leukemia
    • Neuroblastoma metastases
• The history and exam may be encouraging, but persistent pain warrants consideration for more ominous issues and, thus, images may be warranted.

Patellofemoral Pain Syndrome: Management

• Educate and Reassure
  • Do not dismiss as “growing pains.”
  • Generally, gradual improvement and resolution of symptoms can be achieved. [Houghton, 2006]
• Activity Modification
  • Reduce impact exercises
    • Avoid running and jumping sports.
  • Reduce activities that load the knee
    • Avoid squatting exercises and sports (not good to be a catcher in baseball).
• Increase Flexibility
  • Particularly hamstrings, quadriceps, iliotibial band, and gastrocnemius.
  • We all could stand to be more flexible (in all aspects of life).
• Increase Strength
  • Paying attention to appropriate technique to not do more harm!
  • Straight leg raises can strengthen the Quads without placing excessive force on patella. [Ganley, 2006]
  • Water therapy and elliptical trainers can be helpful.
• Cryotherapy (just like Michael Jordan would do)
• NSAIDs
• Corrective orthotics may be helpful in some cases.

Moral of the Morsel

• Appreciate that your words have weight.
  • Even though your exam is reassuring, don’t merely call it a “knee sprain.”
  • Similar to not saying “it’s just a virus.”
• Consider the potential Badness and look for clues… and don’t freak about about getting a few Xrays.  We are talking about major medical radiation.
• If you choose not to image, encourage follow-up… and don’t label it as anything…
  • “Knee Pain not otherwise specified” is better than a misdiagnosis of patellofemoral pain syndrome in a kid who eventual gets diagnosed with osteosarcoma.

References