Anterior Knee Pain

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Definition/Description

Knee - Side View

Anterior knee pain is pain that occurs in the front and central aspect of the knee. Its cause can be due to a number of conditions:

• Patellofemoral pain syndrome
• Chondromalacia Patellae
• Osgood-Schlatter’s disease
• Sinding Larsen Johansson syndrome
• Plica synovialis syndrome
• Knee bursitis/Hoffa’s disease
• Articular cartilage injury
• Bone tumors: Most patients will experience pain in the area of the tumor. Pain can become worse during physical activity and often awakens patients during the night. Bone mass around the tumor becomes weaker and the bone may fracture as a result.
• Osteochondritis dissecans
• Patellafemoral instability/subluxation
  

• Patellar stress fracture: A stress fracture in the patella is caused either by fatigue as a result of submaxiaml stress loads or insufficiency where the bone has been previously weakened due to physiological stress. It reduces shock absorption such that high repetitions of load may lead to a stress fracture.
  
• Patellar tendinitis
• Patellofemoral osteoarthritis
• Pes anserine bursitis: The anserine bursa is one of 13 bursae found around the knee, located just below the pes anserinus. Patients with pes anserine bursitis often complain of spontaneous knee pain with tenderness in the inferomedial aspect of the knee joint.  
• Quadriceps tendinopathy
• Prepatellar bursitis
• Iliotibial band syndrome 

Epidemiology /Etiology

The etiology of anterior knee pain is multifactorial and not well defined due to the variety of symptoms, pain location and pain level experienced by the patient. Underlying factors could be patella abnormalities or muscular imbalances or weakness leading to patella malalignment on flexion and extension. The causes include overuse injuries; tendinopathy, insertional tendinopathy, patellar instability, chondral and steochondral damage .

Characteristics/Clinical Presentation

Clinical classification of anterior knee pain.

There is no clear definition of anterior knee pain and patients can present with various symptoms, making selecting an individual specific non-operative treatment protocol vexing. The European Rehabilitation Panel have devised a guideline which should lead to a improved treatment choice and outcomes. They suggest the following assessment parameters:

1. Symptoms – Pain (location and type) or instability problems?

2. Alignment of the entire lower extremity – Squinting patella? – High q-angle? – Genu valgus? – Genu recurvatum? – Pronation of the subtalar joint?

3. Patellar position – Patella alta? – Patella baja? – Patellar glide? – Patellar tilt? – Patellar rotation?

4. Muscles and soft tissues – Hypotrophy of VMO? – Imbalance between VM and VL? – Weakness of knee extensors, hip flexors and/or hip abductors? – Tightness of the medial retinaculum? – Tightness of lateral muscle structures, hamstrings and/or rectus femoris?

5. Knee function (pain and/or maltracking of the patella) – During different dynamic activities, e.g. stair walking, step-up/step-down exercises and one-leg squat?


Activities of Daily Living:
The main symptom is pain that occurs or worsens when walking down stairs, squatting, depressing the clutch pedal in a car (in the case of left knee pain), wearing high-heeled shoes or sitting for long periods with the knees in a flexed position (‘‘movie sign’’). Patients also experience a certain degree of instability ‘‘in a straight line’’ especially going up and down stairs or ramps .

Individuals with overuse injuries may report a feeling of instability or giving way, although this may not a true giving way (usually associated with internal injury to the knee) but a neuromuscular inhibition as a result of the pain, muscle weakness, patellar or joint instability

Differential Diagnosis

Refered pain from hip joint pathlogy such as capital femoral epiphysis

Refered pain from the Saphenous nerve

Diagnostic Procedures

Evaluation of anterior pain is challenging as it can be non specific and requires a thorough examination, symptom history with an indepth knowledge of the associated structures and typical injury patterns. In younger individuals an assessment of their general growth and development is essential to determine a diagnosis.

Hip and lumbar spine disorders can refer to the knee and need to be excluded.

Some key factors in obtaining an accurate diagnosis are; the pain characteristics, i.e. its location, character, onset, duration, change with activity or rest, aggravating and alleviating factors and any night pain; trauma (acute macrotrauma, repetitive microtrauma, recent/remote); mechanical symptoms (locking or extension block, instability, worse during or after activity); inflammatory symptoms such as morning stiffness, swelling; effects of previous treatments and the current level of function of the patient. Selective use of appropriate imaging, such as Ultrasound and MRI are excellent tools for differential diagnosis and for ruling out sources of intra-articular derangements .. (14)(15)(17)
From various authors it has been concluded that the correct diagnosis can usually be made after a thorough history and physical examination. The history should include a complete investigation of the nature and onset of the athlete's symptoms, past medical history, and the nature of any previous treatment he or she may have received for the problem. The physical examination includes a general lower extremity musculoskeletal examination with determinations of flexibility and limb alignment. (16)(17)

Outcome Measures

The anterior knee pain scale (Kujala scale) is a questionnaire of 13 questions that are specific for the anterior knee pain. This questionnaire is associated with anterior knee pain syndrome (8). This scale tell us how is the gravity of the anterior pain syndrome of the patient. The anterior knee pain scale has a ICC of 0.95 this means that it has a good test-retest reliability. if there are changes the instrument is able to detect the changes and report them(9).
The anterior knee pain scale has a maximum score of 100, if the score is high it indicate lower pain or disability.(8)
Secundary, there is The Lower Extremity Functional Scale (LEFS). It is a test for the anterior knee pain patients to know where are the difficulties that the patient has with activities listed in this questionnaire. This questionnaire is less specific for anterior knee pain patient than the anterior knee pain scale. It is to generally for all the lower extremity. The LEFS also demonstrate an high test-retest reliability and is moderately responsive. It has a ICC of 0.98.(9)

Examination

Inspection
In the inspection the position of the patella tells you a lot to examine patient with anterior knee pain. When the patella isn’t parallel to the femur and when the patella isn’t midway between the two condyles during 20 degrees of knee flexion than there isn’t an optimal patellar position. It is possible than the patient an anterior knee pain syndrome have. (11)
Also hypotrophy of the M. vastus medialis is common in anterior knee pain patient. There is a lower activity of the M. vastus medialis and a higher activity of M. vastus lateralis and it could lead to an imbalance between M. vastus medialis and M. vastus lateralis. (11)
Knee extensors are often weak in patients with anterior knee pain. You can also see it without testing if the quadriceps are less strength than the other (healthy) quadriceps, there can be an atrophy. (11)
Active research
Test for the examination of the anterior knee pain syndrome.
● The step-down test. (10)
● Land from a drop. (10)
Passive research
Stretching for patients with anterior knee pain shows tightness of lateral muscle structures. The quadriceps muscle and the gastrocnemius. To examine the anterior knee pain syndrome the therapist stretch the patient and if there is tightness of lateral muscle structures, the quadriceps muscle and occasionally the hamstrings and the gastrocnemius it can be an example of anterior knee pain. Also if the knee extensors and knee flexors demonstrate a poor flexibility it can be an indication to anterior knee pain. (11)

Medical Management

Anterior knee pain (AKP) is often accompanied with posterior knee instability so one of the treatment for AKP with posterior knee instability is surgery, total knee replacement. (18)

Physical Therapy Management

For a non-specific Anterior Knee pain treatment we need first to focus on the symmetry between the knees before focusing on an operative measures.
Treatment aim is restoration of the symmetry between the 2 knees. To aim that you need to restore the Range of Motion (RoM) and the leg strength.
The first step for this treatment is restoration extension of the knee (also the hyperextension). After the fully recover extension the next step will be restoration of flexion. When the patient recover fully of his RoM then we can begin with strengthen the leg muscles (mostly the quadriceps).
Some exercise that can be use for improving Knee extension:
- Heel Prop (can also be use to train hyperextension)
- Towel extension
Some exercise that can be use for improving Knee flexion:
- Bicycle riding (can also be use to train extension of the knee)
- Wall slides with the heel (active as passive)
Some exercise that can be use for strengthen the knee (only when the RoM of the patient fully is recovered):
- Low Impact aerobic exercise on a stationary bike
- Stair stepping machine

Presentations

Case Study: Adolescent Anterior Knee Pain This presentation was created by Omolara Ajayi in collaboration with: EIM Clinical Excellence Network and Physical Therapy Central. View the presentation

Clinical Bottom Line

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References

1. ↑ Sala D, Silvestre A, Gomar-Sancho F. Intraosseous hyperpressure of the patella as a cause of anterior knee pain. Medscape Orth Sports Med. 1999;3:1–8.
2. ↑ http://orthoinfo.aaos.org/topic.cfm?topic=A00074
3. ↑ Livestrong. Patellofemoral Pain Syndrome Health Byte. Available from: http://www.youtube.com/watch?v=96nP8RaYQ6Y [last accessed 27/08/12]
4. ↑ Crowther MA, Mandal A, Sarangi PP. Propagation of stress fracture of the patella. Br J Sports Med. 2005;39(2):e6. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1725122/pdf/v039p000e6.pdf (accessed 29 Aug 2012)
5. ↑ Helfenstein M Jr, Kuromoto J. Anserine syndrome. Rev Bras Reumatol. 2010;50(3):313-327.
6. ↑ Dixit S, DiFiori JP, Burton M, Mines B. Management of patellofemoral pain syndrome. Am Fam Physician. 2007;75(2):194-202.fckLRAvailable at: http://www.drwilliamsilva.com.br/files/artigos/artigo08.pdf (accessed 29 Aug 2012)
7. Vincente Sanchis-Alfonso, Anterior Knee pain and Patellar Instability (second edition); Springer-Verlag London Limited 2011 ;pagina 66-68 ( = Level of evidence 2C)
8. Anterior knee pain scale; Australian journal of physiotherapy 2009 Vol. 55. Australian Physiotherapy association.
9. Cynthia j. Watson et al. ,Reliability and Responsiveness of the Lower Extremity Functional Scale and the Anterior Knee Pain Scale in Patients With Anterior Knee Pain. Journal of Orthopaedic and Sport Physical Therapy 2005. (Level of evidence 2B)
10. Vincente Sanchis-Alfonso, Holistic approach to understand anterior knee pain. Clinical implications, Knee Surg Sports Traumatol Artrosc (2014) 22:2257-2285 (Level of evidence 2C)

11. Suzanne Werner, Anterior knee pain: an update of physical therapy, Knee Surg Sports Traumatol Artrosc (2014) 22:2286-2294. (Level of evidence 2A)

12. Kim D. Barber Foss et al : Expected Prevalence From the Differential Diagnosis of Anterior Knee Pain in Adolescent Female Athletes During Preparticipation Screening ,Journal of Athletic Training, volume: 47, issue: 5, p. 519 ,2012 (level of evidence:2B)
13. Eva Llopis et al : Anterior knee pain, European journal of radiology , issue: April 21007 (level of evidence:2c)
15. William l. Davis et al : initial evaluation of the athlete with anterior knee pain ,vol 7 issue 2 april 9 pages 55-58(pubmed) (level of evidence:2a)
16. Toby O Smith et al: the contemporary management of anterior knee pain and patellofemoral instability,volume 20, pages s3-s15 ,sept. 2013(pubmed) (level of evidence:1a)

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