Knee Assessment

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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)
Course
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:
Fractures
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
Monoarthritis
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.
References
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