II. Epidemiology
- Most common Running Injury
- Incidence: 6% in U.S.
- Females account for 55% of cases
III. Risk Factors
IV. Causes: Patellofemoral or Anterior Knee Pain
- Soft tissue causes
- Articular causes
- Chondromalacia Patellae
- Patella Osteoarthritis
- Osteochondritis Dissecans of the Knee
- Chondral Fracture
- Functional causes
- Referred pain
V. Mechanism
- Overuse syndrome in athletes
- Sports involving Running, jumping or cutting
- Cyclist or runner going too far, too soon, too fast
- Basketball and Volleyball with repetitive jumping
- Frequent change of playing surface (grass to wood)
- Repetitive squats or lunges
- Excessively worn shoes
- Contact Sports (Football or Rugby)
- Direct impact to Patella
- Degeneration of Patella
- Chondromalacia Patellae
- Osteoarthritis of the knee
-
Patella mal-tracking in the patellofemoral groove
- Asymmetric quadriceps Muscle Strength
- Vastus medialis is often weaker than other Muscle
- Patella is often pulled to the outside (J-tracking)
- Results in local wearing of the articular cartilage
- Increased risk in load bearing positions such as squatting
- Anatomic variation: Increased Q-Angle
- Anatomic variation: Shallow outer patellofemoral groove
- Patella prone to sublux or dislocate laterally
VI. Symptoms
-
Anterior Knee Pain
- Pain beneath, under or peri-Patellar
- Gradually progressive general aching or grating pain
- Associated symptoms
- Stiffness
- Grinding, popping, or clicking sound on knee flexion
- Provocative factors
- Giving-way Sensation (reflex response to pain)
- Patellofemoral Syndrome is associated with painful giving-way
- Contrast with Anterior Cruciate Ligament Tear (ACL Tear) which is associated with painless giving-way
- Findings that make alternative diagnosis more likely
- No locking or catching (contrast with meniscal tear)
- Knee Effusion
- Knee Trauma History
VII. Signs
- Inspection
- Excessive pronation (over pronation) on Running gait (pes pronatus)
- Medial aspect of shoe is worn down the most
- No Knee Effusion
- Abnormal Patella alignment and tracking
- See Patella Tracking Assessment (J Sign)
- Increased Q Angle of the Knee
- Lateral knee structures tight
- Patella Glide Test
- Patella tilt test
- Hamstring tightness (predisposing finding)
- Passive Knee Extension
- Excessive pronation (over pronation) on Running gait (pes pronatus)
- Palpation
- Tender undersurface of medial or lateral Patella
- Crepitation on knee range of motion
- Provocative testing
- Positive Patellar Apprehension Test
- Knee Pain with squatting
- Dynamic Valgus
- Knee shifts into valgus position on squatting while balancing on the affected leg
VIII. Differential Diagnosis
- See Anterior Knee Pain
-
Patellar Tendinopathy
- Pain and focal tenderness at inferior Patellar pole, especially worse with jumping in Patellar Tendinopathy
- Contrast with more generalized Patellar pain, especially descending stairs in Patellofemoral Syndrome
IX. Imaging: Knee XRay
- Not indicated in most cases of Patellofemoral Syndrome
- Used primarily to exclude other causes of Knee Pain
- Consider for refractory symptoms after 8 weeks of management
- Indications
- Age >50 years
- Patellofemoral Osteoarthritis
- Child and Adolescent
- Age >50 years
- Views
- Weight-bearing AP Xray
- Weight-bearing lateral Xray
- Sunrise (Axial view at 20-45 degrees)
X. Management: Medical
- Relative rest
- Avoid squats and lunges
- Reduce Running mileage to painless distance
- Cross-train with biking, swimming, eliptical trainer
- Pain relief
- NSAIDs (variable efficacy)
- Ice Therapy
- Pelvic-femoral rehabilitation
- Patients with dynamic valgus should undergo PT to work hip abduction and external rotation
- See Patellofemoral Knee Exercises
- Quadriceps strengthening
- Isometric progressive resistance Exercises
- Leg-sled Press (45 degree)
-
Eccentric Exercises (especially for Jumper's Knee)
- Patient stands on wedge platform with toes pointing to the bottom of a down slope
- Patient then does standing knee bends to 45 degrees and then fully extends
- Lower extremity StretchingExercises
- Quadriceps Stretching
- Quadriceps strengthening
- Do not load knee at more than 45 degrees flexion
- Isometric quadriceps strengthening
- Sit on floor with affected leg straight and the unaffected leg flexed
- Towel roll placed under affected leg (optional)
- Extend the knee, pressing the towel downwards and hold for 10 seconds
- Repeat 10 repetitions in each of 3 sets
- Straight Leg Raise
- Sit on floor with affected leg straight and the unaffected leg flexed
- Slowly raise the affected leg 8 inches off floor and then return to floor (over 2-4 seconds)
- Repeat 10 repetitions in each of 3 sets
- Hamstring stretches
- Lie supine on floor
- Flex the hip to 90 degrees and grasp to hold in position
- Knee starts at 90 degrees flexion and is fully extended to 90 degrees for 30-60 seconds
- Perform twice for each leg, twice daily
- Hip adductor strengthening Exercises
- Stand with one foot on platform, step or 2x4 wood
- Keep both knees straight and extended
- Start with hips and Pelvis level with floor
- Allow the unsupported leg to slowly lower, and then raise the leg to original position
- Repeat 10 repetitions in each of 3 sets
- Iliotibial Band stretches
- Ankle stretches
- Shoe modifications
- Replace excessively worn Running Shoes
- Over-pronators
- Running Shoe for over-pronators
- Anti-pronation pad
- Formal Orthotic
- Core Muscle Strength (trunk Exercises)
- Avoid provocative factors
- Limit weight on a flexed knee
- Consider cross-training activity
- Reduce mileage and pace
- Avoid uphill and downhill Running
-
Patellar Taping (Kinesiotaping)
- Inconsistent evidence of benefit
- May offer short term pain relief and improve Patellar tracking when used early in course
- Used as an adjunct to physical therapy and Exercises
- Wittingham (2004) J Orthop Sports Phys Ther 34:504-10 [PubMed]
- Callaghan (2012) Cochrane Database Syst Rev (4): CD006717 [PubMed]
-
Patellar bracing
- Not generally recommended
- No significant benefit or inconsistent benefit over Exercises alone
- Despite this, use has increased in sports medicine as of 2012
- Some runners may see benefit
- References
- Not generally recommended
XI. Management: Surgical (under 5-10% of cases)
XII. Course
- Course may be prolonged in athletes as long as 6 years
XIII. References
- Arnold (2018) Am Fam Physician 97(8): 510-6 [PubMed]
- Childress (2013) Am Fam Physician 87(7): 486-90 [PubMed]
- Dixit (2007) Am Fam Physician 75(2):194-204 [PubMed]
- Fulkerson (2002) Am J Sports Med 30:447-56 [PubMed]
- Gaitonde (2019) Am Fam Physician 99(2): 88-94 [PubMed]
- Jones (2015) Am Fam Physician 92(10): 875-83 [PubMed]
- Juhn (1999) Am Fam Physician 60(7): 2012-8 [PubMed]
- Ruffin (1993) Am Fam Physician 47(1): 185-94 [PubMed]
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Related Studies
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 |
Russian | KOLENNOI CHASHECHKI KHONDROMALIATSIIA, КОЛЕННОЙ ЧАШЕЧКИ ХОНДРОМАЛЯЦИЯ |
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 |
Ontology: 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 |
Russian | PATELLO-FEMORAL'NOI BOLI SINDROM, BEDRENNO-KOLENNOCHASHECHNYI BOLEVOI SINDROM, NADKOLENNOI CHASHECHKI I BEDRA BOLEVOI SINDROM, NADKOLENNO-BEDRENNYI BOLEVOI SINDROM, БЕДРЕННО-КОЛЕННОЧАШЕЧНЫЙ БОЛЕВОЙ СИНДРОМ, НАДКОЛЕННО-БЕДРЕННЫЙ БОЛЕВОЙ СИНДРОМ, НАДКОЛЕННОЙ ЧАШЕЧКИ И БЕДРА БОЛЕВОЙ СИНДРОМ, ПАТЕЛЛО-ФЕМОРАЛЬНОЙ БОЛИ СИНДРОМ |
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 |