The Patellofemoral Joint

Knee Assessment

Check our courses
Knee joint

The Knee Joint


Introduction & Epidemiology

Knee injuries are amongst the most common injuries next to shoulder, low-back, and neck pain seen in general practice (Picavet et al. 2003). They can be divided into two logical subgroups: traumatic and atraumatic knee injuries.

Traumatic injuries commonly involve a specific mechanism of injury such as during sports and they usually have a rapid onset. Atraumatic injuries on the other hand are rather overuse injuries that build up gradually over time with an insidious onset.

In primary care, the reported incidence is 13.7/1000 and the prevalence is 19/1000 persons per year for knee injuries (van der Linden et al. 2004)



The course of knee complaints appears not to be too favorable. Reports show that at a 12-month follow-up, 33% of patients with atraumatic knee pain and 25% of patients with traumatic knee pain report full recovery (Wagemakers et al. 2012).



Prognostic factors

For atraumatic knee injuries, the following prognostic factors were associated with persistent knee symptoms after 1 year (Belo et al. 2009):

  • age >60 years
  • low educational level
  • kinesiophobia
  • comorbidity of the skeletal system

For traumatic knee injuries, however, Wagemakers et al. (2012) report the following prognostic factors:

  • age >40
  • female gender
  • pain score >5
  • popping sensation during trauma

Multivariate logistic regression analysis revealed that only age >40 was a prognostic factor for persistent complaints at the 1-year follow-up.


Red flags

There are several specific pathologies that count as red flags in the knee joint. These are:


Characteristic signs and symptoms are:

  • Swelling/bruising over the bone
  • Deformity
  • Painful ROM
  • Tenderness

To assess for a fracture of the knee, you can make use of the Ottawa Knee Rules or Pittsburgh decision rule:


Post-traumatic neurovascular damage

This usually involves two or more ligament injuries as well (ACL, PCL, Collateral).

Characteristic signs are:

  • Hematoma
  • Groove at the lateral or medial joint line
  • Markedly visible and palpable deformity
  • Damage to the n. peroneus communis, n.tibialis (hypofunction of muscles innervated by the nerve), a. tibialis posterior and/or a. dorsalis pedis (àpalpate for pulsation)


Complete rupture of the extensor group

This may result from low-velocity trauma (elderly), sports or motor vehicle accident (adults)

Characteristic signs are:

  • Inability to lift the extended leg
  • Palpable groove in the quadriceps muscle
  • Difference in level of the two patellae (alta: patella tendon affected, bacha: quadriceps tendon affected)
  • Inability to bear weight on the leg



Inflammation of a joint due to infection from diagnostic or therapeutic intervention, skin damage, co-morbidities, endoprosthetics, STDs, GI infection, IV drug use, tuberculosis, gout, gonorrhea, acute rheumatic arthritis, sickle cell disease, reactive arthritis, medication use: diuretics, corticosteroids

Characteristic signs include:

  • General malaise
  • Swelling of the entire joint (not moving, tense skin)
  • Redness of the joint
  • Local increase in temperature
  • Decrease in ROM


Spontaneous hemarthrosis

This is mainly a risk in people who have disorders such as hemophilia or those who use anticoagulants.


Bone- or soft-tissue tumor

While you assess for malignancy during your general screening, localized tumors can have the following signs:

  • Mild, alternating pain over weeks
  • Palpable mass at the end of long bones
  • Swelling of soft tissues
  • Growth in a lesion/swelling that’s been existing for a longer period
  • Swelling below the muscle fascia
  • Swelling at a site distant to the site of trauma



Basic Assessment

Depending on the outcome, your basic assessment can give you the following info:1)  Limitations in range of motion and their end-feel can guide in structural assessment (e.g. bone to bone=osteoarthritis, empty=tendinopathy due to pain)

It’s best to start with Active Range of Motion Assessment:

Standard values for the range of motion in different directions are as follows: 

Flexion: 0-135°

Extension: 0-15°

AROM assessment is then typically followed by Passive Range of Motion Assessment (PROM) which you can watch with a click on the following video:

During PROM assessment, it’s important to compare the range of motion as well as the end-feel of the affected knee with the unaffected side.



Artus, Majid et al. “Generic Prognostic Factors for Musculoskeletal Pain in Primary Care: A Systematic Review.” BMJ Open 7.1 (2017): e012901. PMC. Web. 6 Sept. 2018.

Belo, J. N., et al. “Prognostic factors in adults with knee pain in general practice.” Arthritis Care & Research 61.2 (2009): 143-151.

Collins NJ, Bierma-Zeinstra SM, Crossley KM, van Linschoten RL, Vicenzino B & van Middelkoop M. (2013) Prognostic factors for patellofemoral pain: a multicentre observational analysis. Br J Sports Med. 2013 Mar;47(4):227–33.

Kastelein M, Luijsterburg PA, Wagemakers HP, Bansraj SC, Berger MY, Koes BW, Bierma-Zeinstra SM. Diagnostic value of history taking and physical examination to assess effusion of the knee in traumatic knee patients in general practice. Archives of physical medicine and rehabilitation. 2009 Jan 1;90(1):82-6.

Picavet, H. S. J., and J. S. A. G. Schouten. “Musculoskeletal pain in the Netherlands: prevalences, consequences and risk groups, the DMC3-study.” Pain 102.1-2 (2003): 167-178.

Van der Linden M, Westert G, Bakker D & Schellevis F. (2004) Tweede Nationale Studie naar ziekten en verrichtingen in de huisartspraktijk. Klachten en aandoeningen in de bevolking en in de huisartspraktijk. Utrecht/Bilthoven: NIVEL/RIVM. 2004

Wagemakers HPA, Luijsterburg PAJ, Heintjes EM, Berger MY, Verhaar JAN, Koes BW & Bierma-Zein- stra SMA. (2012) Predictors of persistent complaints after knee injury in primary care. Br J Gen Pract. 2012 Aug;62(601):e561–6.

Like what you're learning?

Follow a course

  • Learn from wherever, whenever, and at your own pace
  • Interactive online courses from an award-winning team
  • CEU/CPD accreditation in the Netherlands, Belgium, US & UK
Online Course

How to Boost Your Knowledge about the 23 Most Common Orthopedic Pathologies in Just 40 Hours

Online course banner background (1)
Upper extremity mockup

What customers have to say about this online course

Download our FREE app