Orthopedics Book

Joint dislocation




Patellofemoral Syndrome

Aka: Patellofemoral Syndrome, Chondromalacia Patellae, Patellofemoral Pain Syndrome, Miserable Malalignment Syndrome, Runner's Knee, PFPS
  1. Epidemiology
    1. Most common Running Injury
    2. Incidence: 6% in U.S.
    3. Females account for 55% of cases
  2. Risk Factors
    1. Female gender
    2. Overuse
    3. Provocative activities
      1. Running
      2. Squatting
      3. Climbing stairs (and going downstairs)
    4. Mechanical factors
      1. Dynamic valgus (with maltracking) - see below
      2. Rear foot eversion
      3. Pes pronatus
      4. Patellar instability
      5. Quadriceps weakness
  3. Causes: Patellofemoral or Anterior Knee Pain
    1. Soft tissue causes
      1. Prepatellar Bursitis
      2. Patella Tendonitis
      3. Meniscus Tear
    2. Articular causes
      1. Chondromalacia Patellae
      2. Patella Osteoarthritis
      3. Osteochondritis Dissecans of the Knee
      4. Chondral Fracture
    3. Functional causes
      1. Patella instability
      2. Synovial plica
        1. Synovium caught between Patella and femur
    4. Referred pain
      1. Back pain
      2. Hip Pain
      3. Ankle pain
  4. Mechanism
    1. Overuse syndrome in athletes
      1. Sports involving Running, jumping or cutting
      2. Cyclist or runner going too far, too soon, too fast
      3. Basketball and Volleyball with repetitive jumping
      4. Frequent change of playing surface (grass to wood)
      5. Repetitive squats or lunges
      6. Excessively worn shoes
      7. Contact Sports (Football or Rugby)
        1. Direct impact to Patella
    2. Degeneration of Patella
      1. Chondromalacia Patellae
      2. Osteoarthritis of the knee
    3. Patella mal-tracking in the patellofemoral groove
      1. Asymmetric quadriceps Muscle Strength
      2. Vastus medialis is often weaker than other Muscle
      3. Patella is often pulled to the outside (J-tracking)
      4. Results in local wearing of the articular cartilage
      5. Increased risk in load bearing positions such as squatting
    4. Anatomic variation: Increased Q-Angle
      1. Increased angle between femur and tibia (Q-Angle)
        1. Women more often have larger Q-angle
        2. However Q-angle has not been consistently shown as significant risk
      2. On Quadriceps contraction, Patella is pushed outward
      3. Leads to mal-tracking of the Patella as above
    5. Anatomic variation: Shallow outer patellofemoral groove
      1. Patella prone to sublux or dislocate laterally
  5. Symptoms
    1. Anterior Knee Pain
      1. Pain beneath, under or peri-Patellar
      2. Gradually progressive general aching or grating pain
    2. Associated symptoms
      1. Stiffness
      2. Grinding, popping, or clicking sound on knee flexion
    3. Provocative factors
      1. Going up or down stairs, or down hills
      2. Running
      3. Squatting
      4. Kneeling
      5. Prolonged sitting with knee bent (Theater sign)
    4. Giving-way Sensation (reflex response to pain)
      1. Patellofemoral Syndrome is associated with painful giving-way
      2. Contrast with Anterior Cruciate Ligament Tear (ACL Tear) which is associated with painless giving-way
    5. Findings that make alternative diagnosis more likely
      1. No locking or catching (contrast with meniscal tear)
      2. Knee Effusion
      3. Knee Trauma History
  6. Signs
    1. Inspection
      1. Excessive pronation (over pronation) on Running gait (pes pronatus)
        1. Medial aspect of shoe is worn down the most
      2. No Knee Effusion
      3. Abnormal Patella alignment and tracking
        1. See Patella Tracking Assessment (J Sign)
        2. Increased Q Angle of the Knee
      4. Lateral knee structures tight
        1. Patella Glide Test
        2. Patella tilt test
      5. Hamstring tightness (predisposing finding)
        1. Passive Knee Extension
    2. Palpation
      1. Tender undersurface of medial or lateral Patella
      2. Crepitation on knee range of motion
    3. Provocative testing
      1. Positive Patellar Apprehension Test
      2. Knee Pain with squatting
    4. Dynamic Valgus
      1. Knee shifts into valgus position on squatting while balancing on the affected leg
  7. Differential Diagnosis
    1. See Anterior Knee Pain
    2. Patellar Tendinopathy
      1. Pain and focal tenderness at inferior Patellar pole, especially worse with jumping in Patellar Tendinopathy
      2. Contrast with more generalized Patellar pain, especially descending stairs in Patellofemoral Syndrome
  8. Imaging: Knee XRay
    1. Not indicated in most cases of Patellofemoral Syndrome
      1. Used primarily to exclude other causes of Knee Pain
      2. Consider for refractory symptoms after 8 weeks of management
    2. Indications
      1. Age >50 years
        1. Patellofemoral Osteoarthritis
      2. Child and Adolescent
        1. Osteochondritis Dissecans
        2. Bone Neoplasms
      1. Weight-bearing AP Xray
      2. Weight-bearing lateral Xray
      3. Sunrise (Axial view at 20-45 degrees)
  9. Management: Medical
    1. Relative rest
      1. Avoid squats and lunges
      2. Reduce Running mileage to painless distance
      3. Cross-train with biking, swimming, eliptical trainer
    2. Pain relief
      1. NSAIDs (variable efficacy)
      2. Ice Therapy
    3. Pelvic-femoral rehabilitation
      1. Patients with dynamic valgus should undergo PT to work hip abduction and external rotation
    4. See Patellofemoral Knee Exercises
      1. OrthoPFSExercises.htm
    5. Quadriceps strengthening
      1. Isometric progressive resistance Exercises
      2. Leg-sled Press (45 degree)
    6. Eccentric Exercises (especially for Jumper's Knee)
      1. Patient stands on wedge platform with toes pointing to the bottom of a down slope
      2. Patient then does standing knee bends to 45 degrees and then fully extends
    7. Lower extremity StretchingExercises
      1. Quadriceps Stretching
      2. Quadriceps strengthening
        1. Do not load knee at more than 45 degrees flexion
        2. Isometric quadriceps strengthening
          1. Sit on floor with affected leg straight and the unaffected leg flexed
          2. Towel roll placed under affected leg (optional)
          3. Extend the knee, pressing the towel downwards and hold for 10 seconds
          4. Repeat 10 repetitions in each of 3 sets
        3. Straight Leg Raise
          1. Sit on floor with affected leg straight and the unaffected leg flexed
          2. Slowly raise the affected leg 8 inches off floor and then return to floor (over 2-4 seconds)
          3. Repeat 10 repetitions in each of 3 sets
      3. Hamstring stretches
        1. Lie supine on floor
        2. Flex the hip to 90 degrees and grasp to hold in position
        3. Knee starts at 90 degrees flexion and is fully extended to 90 degrees for 30-60 seconds
        4. Perform twice for each leg, twice daily
      4. Hip adductor strengthening Exercises
        1. Stand with one foot on platform, step or 2x4 wood
        2. Keep both knees straight and extended
        3. Start with hips and Pelvis level with floor
        4. Allow the unsupported leg to slowly lower, and then raise the leg to original position
        5. Repeat 10 repetitions in each of 3 sets
      5. Iliotibial Band stretches
      6. Ankle stretches
        1. Gastrocnemius Muscle
        2. Soleus Muscle
    8. Shoe modifications
      1. Replace excessively worn Running Shoes
      2. Over-pronators
        1. Running Shoe for over-pronators
        2. Anti-pronation pad
        3. Formal Orthotic
    9. Core Muscle Strength (trunk Exercises)
    10. Avoid provocative factors
      1. Limit weight on a flexed knee
      2. Consider cross-training activity
      3. Reduce mileage and pace
      4. Avoid uphill and downhill Running
    11. Patellar Taping (Kinesiotaping)
      1. Inconsistent evidence of benefit
      2. May offer short term pain relief and improve Patellar tracking when used early in course
      3. Used as an adjunct to physical therapy and Exercises
      4. Wittingham (2004) J Orthop Sports Phys Ther 34:504-10 [PubMed]
      5. Callaghan (2012) Cochrane Database Syst Rev (4): CD006717 [PubMed]
    12. Patellar bracing
      1. Not generally recommended
        1. No significant benefit or inconsistent benefit over Exercises alone
        2. Despite this, use has increased in sports medicine as of 2012
        3. Some runners may see benefit
      2. References
        1. Lun (2005) Clin J Sport Med 15:235-40 [PubMed]
        2. Swart (2012) Br J Sports Med 46(8): 570-77 [PubMed]
  10. Management: Surgical (under 5-10% of cases)
    1. Indications
      1. Persistent symptoms >6-12 months
      2. Refractory to formal rehabilitation program
      3. Other Knee Pain causes excluded
    2. Procedures
      1. Diagnostic Knee Arthroscopy
      2. Smoothing of Patella articular cartilage
      3. Lateral Release
      4. Patellar tendon relocation
    3. Efficacy
      1. Arthroscopy adds no benefit over home Exercise in Patellofemoral Pain Syndrome
        1. Kettunen (2007) BMC Med 5:38 [PubMed]
  11. Course
    1. Course may be prolonged in athletes as long as 6 years
  12. References
    1. Arnold (2018) Am Fam Physician 97(8): 510-6 [PubMed]
    2. Childress (2013) Am Fam Physician 87(7): 486-90 [PubMed]
    3. Dixit (2007) Am Fam Physician 75(2):194-204 [PubMed]
    4. Fulkerson (2002) Am J Sports Med 30:447-56 [PubMed]
    5. Gaitonde (2019) Am Fam Physician 99(2): 88-94 [PubMed]
    6. Jones (2015) Am Fam Physician 92(10): 875-83 [PubMed]
    7. Juhn (1999) Am Fam Physician 60(7): 2012-8 [PubMed]
    8. Ruffin (1993) Am Fam Physician 47(1): 185-94 [PubMed]

Chondromalacia Patellae (C0008475)

Definition (MSH) A degeneration of the ARTICULAR CARTILAGE of the PATELLA, caused by a decrease in sulfated MUCOPOLYSACCHARIDES in the ground substance. When accompanied by pain, it is sometimes considered part of or confused with PATELLOFEMORAL PAIN SYNDROME.
Concepts Disease or Syndrome (T047)
MSH D046789
ICD9 717.7
ICD10 M22.4
SnomedCT 36071006, 156521009
Dutch chondromalacia patellae, chondropathie van patella, chondromalacie; patella, chondropathie; patella, patella; chondromalacie, patella; chondropathie, Chondromalacia patellae, Chondromalacie, patella
German Chondromalazie der Patella, Chondromalacia patellae, Chondromalazie der Kniescheibe, Chondropathia patellae
Portuguese Condromalacia da rótula, Condromalacia da Patela, Condromalacia Patelar
Spanish Condromalacia rotuliana, Condromalacia de la rótula, condromalacia de la rótula (trastorno), enfermedad de Buedinger - Ludloff - Laewen, condromalacia de rótula, condromalacia de rótula (trastorno), condromalacia de la rótula, condromalacia rotuliana, degeneración del cartílago de la articulación rotuliana, Condromalacia de la Rótula
Japanese 膝蓋軟骨軟化症, シツガイナンコツナンカショウ
Swedish Chondromalacia patellae
English PATELLA, CHONDROMALACIA OF, patellar chondromalacia (diagnosis), patellar chondromalacia, Chondromalacia Patellae [Disease/Finding], chondromalacia patellae, patellae chondromalacia, Chondromalacia;patella, chondromalacia of patella, chondromalacia patella, Chondromalacia patella, Patella, Chondromalacia Of, Chondromalacia patellae (disorder), Chondromalacia of patella, Chondromalacia patellae, Degeneration of articular cartilage of patella, Chondromalacia of patella (disorder), chondromalacia; patella, chondropathia patellae, chondropathy; patella, patella; chondromalacia, patella; chondropathy, Buedinger-Ludloff-Laewen disease, Chondromalacia Patellae, Softening of articular cartilage of patella, patella chondromalacia
Czech chondromalacie čéšky, chondromalacia patellae, Chondromalacie pately
Finnish Polvilumpion kondromalasia
Korean 무릎뼈의 연골연화
Polish Rozmiękanie chrząstki rzepki, Chondromalacja rzepki
Hungarian Patella chondromalacia, Chondromalacia patellae
Norwegian Patellofemoralt syndrom, Chondromalacia patellae
French Chondromalacie de la rotule, Chondromalacie rotulienne, Chondromalacie de la patella, Chondromalacie patellaire
Italian Condromalacia della rotula
Derived from the NIH UMLS (Unified Medical Language System)

Patellofemoral Pain Syndrome (C0877149)

Definition (MSH) A syndrome characterized by retropatellar or peripatellar PAIN resulting from physical and biochemical changes in the patellofemoral joint. The pain is most prominent when ascending or descending stairs, squatting, or sitting with flexed knees. There is a lack of consensus on the etiology and treatment. The syndrome is often confused with (or accompanied by) CHONDROMALACIA PATELLAE, the latter describing a pathological condition of the CARTILAGE and not a syndrome.
Concepts Disease or Syndrome (T047)
MSH D046788
Italian Sindrome dolorosa femororotulea, Sindrome dolorosa del ginocchio anteriore, Sindrome patellofemorale, Sindrome del dolore dell'area anteriore del ginocchio, Sindrome rotuleo-femorale
Dutch kniepijnsyndroom, patellofemoraal pijnsyndroom, Patellofemoraal pijnsyndroom
French Syndrome de douleur dans le genou antérieur, Syndrome douloureux fémoro-patellaire, SDAG, Syndrome douloureux antérieur du genou, Syndrome fémoro-­patellaire, Syndrome fémoro­patellaire, Syndrome rotulien
German patellofemorales Schmerzsyndrom, Patellofemorales Schmerzsyndrom, Patello-femorales Schmerzsyndrom, Patello-femorales Syndrom, Schmerzsyndrom des vorderen Kniebereichs
Portuguese Síndrome dolorosa anterior do joelho, Síndrome da Dor Patelofemoral, Síndrome da Dor Femoropatelar, Síndrome da Dor Femororrotuliana, Síndrome de dor patelofemoral
Spanish Síndrome doloroso de la parte anterior de la rodilla, Síndrome de Dolor Femororrotuliano, Síndrome de Dolor Fémoropatelar, Síndrome de dolor patelofemoral, Síndrome de Dolor Patelofemoral
Japanese 前膝部疼痛症候群, ゼンシツブトウツウショウコウグン, 膝蓋大腿痛症候群, 膝前部痛症候群, 膝蓋大腿症候群, 膝蓋大腿関節痛症候群, シツガイダイタイカンセツツウショウコウグン
Swedish Patellofemoralt smärtsyndrom
Czech patelofemorální syndrom, Syndrom patelofemorální bolesti, Syndrom bolesti přední části kolene
Finnish Patellofemoraalinen kipuoireyhtymä
English patellofemoral syndrome, patellofemoral syndrome (diagnosis), Patellofemoral Pain Syndrome [Disease/Finding], pain patellofemoral syndrome, patellofemoral pain syndrome, Patellofemoral pain syndrome, Anterior Knee Pain Syndrome, Pain Syndrome, Patellofemoral, Patellofemoral Pain Syndrome, Patellofemoral Syndrome, Anterior knee pain syndrome, patello femoral syndrome, Patello femoral syndrome
Polish Zespół bólowy rzepkowo-udowy
Hungarian Patellofemoralis fájdalom syndroma, Elülső térd fájdalom syndroma
Norwegian Patellofemoralt smertesyndrom, Patellofemorale lidelser
Derived from the NIH UMLS (Unified Medical Language System)

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