High Yield Topics

Redundant Plica

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Ovid: 5-Minute Sports Medicine Consult, The


Redundant Plica
Sean A. Cupp
Basics
Description
  • A plica is a redundant fold of embryonic synovium adjacent to the patella.
  • 3 common locations for plicae are superior, medial, and inferior.
  • A 4th, lateral location is very rare and controversial.
  • The inferior location is the most common, and the medial is the least common, but the medial plica is the most clinically relevant and most studied (1)[C].
  • Synonym(s): Patellofemoral syndrome; Synovitis of the knee
Epidemiology
Incidence
Present in 18–80% of knees
Prevalence
  • Predominant gender: Female > Males.
  • Predominant age: Occurs more often in growing adolescents
Risk Factors
  • Congenital presence of plica
  • Extensor mechanism malalignment, eg, quadriceps/vastus medialis oblique (VMO) weakness, increased Q-angle
  • Repetitive flexing and extending of the knee, eg, running, jumping
Etiology
  • Normal elastic synovial tissue becomes thickened and swollen owing to inflammation and is replaced by fibrotic tissue that is tight and inelastic.
  • This causes impingement between the patella and medial femoral condyle, resulting in mechanical synovitis.
  • This secondary synovitis can alter the normal patellofemoral joint mechanism, leading to articular cartilage softening and degeneration and chondromalacia.
  • Direct shearing forces from the inflamed plica on the articular cartilage may worsen the chondromalacia (2)[C].
Diagnosis
History
  • Complaint of intermittent, dull anterior knee pain
  • Pain over suprapatellar or medial peripatellar region
  • Pain worse after long periods of knee flexion (eg, sitting), especially when accompanied by a distinct snap or pop when knee is extended
  • May have a history of overuse or direct trauma
  • Painful catching or pseudolocking episodes over medial patellofemoral joint
  • May describe feeling of instability with episodes of pain
Physical Exam
  • Episodes of anterior knee pain
  • May be associated with swelling of the knee
  • Patient may describe a feeling of knee instability, “catching,” “buckling,” or “giving way” with episodes of pain.
  • Palpation over the medial patellofemoral joint may demonstrate a tender thickened band in the anterior synovium.
  • Often difficult to palpate; best done while passively flexing and extending the knee while holding the tibia in internal rotation
  • Kick test:
    • Patient lies supine with knees flexed to 90 degrees
    • Patient quickly extends knee, imitating a soccer kick
    • Test is positive if it reproduces pain (3)[C].
  • Mediopatellar plica test:
    • Patient lies supine with knees in full extension
    • Examiner's thumb applies manual force between medial femoral condyle and patella while knee is flexed to 90 degrees
    • Test is positive if pain in extension resolves or diminishes with knee in flexion (4)[A].
  • May find other problems associated with extensor mechanism malalignment, eg, chondromalacia patella, patellar subluxation
  • Assess hamstring and heel cord tightness because these conditions tend to aggravate the problem.
Diagnostic Tests & Interpretation
Imaging
  • X-ray studies do not usually show any bony abnormality. They are helpful to exclude other sources of pathology: Osteochondritis dissecans, loose bodies, osteoarthritis, fractures, osteophytes (1)[C].
  • Patellar views (eg, sunrise, Merchant, Hughston patellar views) may demonstrate a lateral patellar tilt consistent with weakness of the vastus medialis or an increased Q-angle.
  • MRI may demonstrate inflammation and thickening of the anteromedial synovium of the knee in extreme chronic cases; helps to exclude meniscal and articular cartilage pathology.
  • US imaging may have limited use in evaluating thickening of the synovial plica but is very dependent on operator experience and expertise.
Differential Diagnosis
  • Other painful patellofemoral conditions, eg, chondromalacia patella, osteochondritis dissecans of the medial femoral condyle, patellar instability/subluxation
  • Medial meniscus tear, pes anserine bursitis, medial collateral ligament sprain
Treatment
  • Analgesia: NSAIDs
  • Protection:
    • Activity modification
    • Consider external patellar support.
  • Rest:
    • Relative rest to reduce repetitive flexion of the knee
    • May consider short-term straight-leg immobilization (1–3 days) if pain is severe
  • Ice: 20 min every 2–3 hr to reduce inflammation until swelling and pain have resolved.
  • Compression: Elastic bandage can be used for comfortable level of compression during the acute phase to help to reduce swelling.

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  • Elevation: Elevating the knee above the level of the heart as much possible may help to reduce swelling within the plica.
  • Support:
    • Consider using an open patellar knee brace with a patellar support to reduce patellar mobility and recurrent “pinching” of the plica; may help to reduce the chance of recurrent trauma to the plica when the patient returns to activity.
    • McConnell taping (a physical therapy taping technique using strong supportive tape surrounding the patella) may be used for short-term improvement in patellar alignment and reduction in patellar hypermobility.
    • Foot orthotics if patient has significant pes planus or overpronation; may help symptomatic knee valgus deformity and decrease the Q-angle
Additional Treatment
Additional Therapies
  • 6–8 wks of home exercises or formal physical therapy (1,5)[C]
  • VMO strengthening (quad sets, straight-leg raises, terminal arc extensions of the knee)
  • Hamstring stretching
  • Heel-cord stretching
  • Ice for 15–20 min after exercise
  • Consider phonophoresis.
Surgery/Other Procedures
  • Injection:
    • Intraarticular corticosteroid injection into the knee often produces a decrease in inflammation of the plica and associated symptoms and may be considered if initial conservative treatment has failed.
    • Corticosteroid injection may help to resolve the problem and negate the need for arthroscopic intervention.
    • Intraplical injection is difficult, and needle placement is unreliable and therefore not recommended (5)[C].
  • Surgery:
    • If plica is fibrotic and symptoms persist, arthroscopic removal of the plica is indicated.
    • For chronic painful plica, arthroscopic removal often provides good relief of symptoms and return to normal function.
    • Surgery should be combined with rehabilitative strengthening of the VMO to reduce the chance of recurrence.
    • Arthroscopy can result in further irritation and scarring of synovial plica, thus worsening symptoms (1,5)[C].
References
1. Sznajderman T, Smorgick Y, Lindner D, et al. Medial plica syndrome. Isr Med Assoc J. 2009;11:54–57.
2. Lyu SR, Hsu CC. Medial plicae and degeneration of the medial femoral condyle. Arthroscopy. 2006;22:17–26.
3. Irha E, Vrdoljak J. Medial synovial plica syndrome of the knee: a diagnostic pitfall in adolescent athletes. J Pediatr Orthop B. 2003;12:44–48.
4. Kim SJ, Lee DH, Kim TE. The relationship between the MPP test and arthroscopically found medial patellar plica pathology. Arthroscopy. 2007;23:1303–1308.
5. Griffith CJ, Laprade RF. Medial plica irritation: diagnosis and treatment. Curr Rev Musculoskelet Med. 2008;1:53–60.
Additional Reading
Boyd CR, Eakin C, Matheson GO. Infrapatellar plica as a cause of anterior knee pain. Clin J Sport Med. 2005;15:98–103.
Calmbach WL, Hutchens M. Evaluation of patients presenting with knee pain: Part II. Differential diagnosis. Am Fam Physician. 2003;68:917–922.
Codes
ICD9
727.83 Plica syndrome
Clinical Pearls
  • Plica bands are congenital. An inflamed plica usually occurs after chronic and repetitive pinching of the lining of the knee caused by weakness of the quadriceps (vastus medialis) muscle or a larger than normal angle from the hip to the knee pulling the kneecap more sideways (commonly seen in growing adolescent females) or after an acute trauma to the front of the knee.
  • Unless the inflammation has been present for a long time and scar tissue has formed, the symptoms of an inflamed plica often will resolve with ice, NSAIDs, and rehabilitative exercises. The plica band can only be removed with surgery, and often the resulting scar tissue can mimic the inflamed plica symptoms.
  • Pain that occurs with plica irritation usually occurs only after the plica becomes inflamed, often from being pinched between the kneecap and thigh bone from such activities as running, jumping, going up and down stairs, or sitting with the knee flexed for an extended period of time.


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