Knee Pain Assessment What You Need to Know

Introduction

For any patient presenting with knee pain, the initial evaluation should focus in excluding urgent cases and considering the need for referral to a more appropriate specialist.

Patients for urgent referral include those with;

Severe pain or swelling
Severe instability
Patients unable to bear weight (Associated with acute trauma)
Patients with signs of joint Infection.
- Fever
- Swelling
- Erythema
- Limited ROM

Subjective Assessment

Key subjective information to obtain includes;

Age
Sex
Location of any symptoms
Onset
Duration
Quality of pain (VAS)
Associated Mechanical or Systemic symptoms
History of swelling
Description of preceding trauma if any
Previous medical history/surgical procedures.

Location

Anterior knee pain

Isolated anterior knee pain suggests involvement of patella, patella tendon or its attachments

This would suggest disorders such as;

Patellofemoral pain syndrome which is exacerbated by prolonged sitting or climbing stairs.
Quadricep or patella tendinopathy (Jumpers’ knee) characterized by anterior knee pain in athletes or other adults with overuse from running or jumping sports.
Osgood-Schlatter Disease (tibial apophysitis) or Sinding-Larsen-Johnson syndrome (distal patellar apophysitis) characterized by insidious onset of anterior pain in adolescents during rapid growth periods as well as overuse.
Prepatellar bursitis which causes patellar-localized pain and swelling. It can occur with isolated blunt trauma, repetitive injury or infection of the overlying skin.

Medial or Lateral pain

Medial or lateral knee pain occurring with corresponding joint line tenderness may indicate meniscal derangement or a sprain or rupture of a collateral ligament (In Acute injury and in Chronic Overuse).

Pes anserine bursitis in a common cause of medial knee pain often caused by overuse or blunt injury (pain exacerbated by flexion and extension of knee).

In adolescents experiencing medial knee pain with or without concurrent hip pain should be evaluated for slipped capital femoral epiphysis. (referred pain).

Chronic lateral knee pain in cyclists, or other activities involving knee flexion is common in iliotibial band syndrome.

Posterior knee pain

Isolated posterior knee pain is less common. However, it may occur in symptomatic popliteal (baker’s) cyst.

Posterior knee pain after acute trauma may suggest injury of the posterior cruciate ligament and the posterior potion of the meniscus, quadriceps tendons or the neurovascular structures.

Chronic posterior knee pain may suggest hamstring tendinopathy.

Diffuse knee pain

Chronic, diffuse knee pain in adults older than 50 years is common in knee osteoarthritis especially if the pain is worse at the end of the day, exacerbated by weight bearing activities and is relieved by rest.

Acute diffuse atraumatic pain may indicate an infectious etiology, gout or rheumatoid arthritis. Rheumatoid arthritis is more likely if pain is bilateral and occurs simultaneously in other joints.

In adolescents, atraumatic diffuse pain that worsens with activity requires imaging to assess for osteochondrosis.

Atraumatic diffuse pain that persists at rest or that which is worse at night should raise suspicion on malignancy.

Mechanical Symptoms

Mechanical symptoms such as locking, buckling or catching suggest internal derangement, possibly instability but they can also occur in medial plica syndrome.

Popping sensation at the time of injury may occur in meniscal or ligamentous tears.

Locking of the knee in flexion, suggests meniscal tear.

Swelling

In acute injury, joint effusion strongly suggests internal derangement.

Swelling that occurs immediately (mins – hours) after injury suggests a ligament rapture, intraarticular fracture or patella dislocation.

Swelling that appears hours – days after injury suggests a meniscal tear.

Atraumatic swelling with erythema or palpable warmth implies gout, or pseudogout, arthritic flare or infection.

Swelling that is limited to borders of the patellar suggests prepatellar bursitis.

Mechanism of Injury

To determine mechanism of injury, gather information about pain onset, positioning of knee during and after injury and subsequent weight bearing status.

Meniscal tears result commonly from twisting injuries in the weight bearing knee.

Ligamentous rapture result from excess deceleration applied to weigh bearing, fixed, lower extremity or a direct blow to the lateral or medial knee.

Fracture should be considered if patient are unable to walk or limp at least four steps both immediately after injury and at first presentation.

Objective Assessment

Objective assessment will involve;

Inspection
Palpation
Range of Motion
Neurovascular testing
Special Provocative Tests
Radiographic examination which should be reserved for;
1. Chronic knee pain (> 6 weeks)
1. Acute Traumatic pain

Inspection

Inspect for;

erythema
Swelling
Bruising
Lacerations
Gross deformity
Discoloration
Asymmetry of bony or soft tissue landmarks (atrophy and valgus or varus)

Palpation

Palpation to assess for pain over all the bony and soft tissue landmarks, assess warmth and effusion.

Pes anserine bursitis manifests as a tender nodule over the medial proximal tibia approximately 3 cm distal to the joint line.

Plica can be appreciated as a thin band near / overlying the medial joint line.

A joint that is warm or warmer than tissue above or below the joint indicates infection or inflammation

Ballottement test and milking of the suprapatellar pouch while patient supine and the injured knee is in extension to assess joint effusion.

Range of motion

Normal range of motion extension (0 to -10 degrees) to flexion (135 degrees)

Special (provocative tests)

Special/provocative tests are used to assess specific structures of the knee. Accuracy of each test varies. Pain and effusion may limit the usefulness of these tests in the acute setting requiring repeated testing or waiting until effusion has reduced.

Tests for anterior cruciate ligament injury

Lachman test

Patient lying supine
Leg slightly externally rotated and flexed (15^o to 30^o)
Place one hand behind the tibia (thumb being on the tibial tuberosity) and the other on the patient’s thigh.
Pull the tibia anteriorly
Test positive if there is a soft or mushy end feel.

Anterior Drawer test of the knee

Patient lying supine
Hip flexed at 45^o
Knee flexed at 90^o
Stabilize the foot (by sitting on the dorsum of the foot)
While ensuring that the hamstrings are relaxed, grasp the proximal lower leg, just below the tibial plateau or tibiofemoral joint line, and attempt to move the lower leg anteriorly.
Test is positive if there is a lack of end feel or if there is excessive laxity compared to the other limb.

Pivot Shift Test

Patient lying supine with legs relaxed.
One hand of the examiner at the heel while the other hand is at the proximal tibia just distal to the knee.
The examiner applies valgus stress and an axial load while internally rotating the tibia and flexing the knee.
Test is positive if there is subluxation of the tibia.

Test for posterior cruciate ligament injury.

Posterior drawers test

Patient lying supine
Hip flexed at 45^o
Knee flexed at 90^o
Stabilize the foot (by sitting on the dorsum of the foot)
Grasp the proximal lower leg, just below the tibial plateau or tibiofemoral joint line, and attempt to move the lower leg posteriorly.
Test is positive if there is a lack of end feel or if there is excessive laxity compared to the other limb.

Meniscal tear tests

Thessaly test

This test aims to reproduce dynamic joint loading.

Patients stands flatfooted on one leg (5^o knee flexion)
With the examiner supporting the patient via a his/her outstretched hand, the patient rotates his/her knee and body internally and externally three times.
The patient will then repeat the same again but with the knee flexed at 20^o.
Perform the test on the sound limb first, then again on the affected limb.
Test is positive if there is reproduction pain and mechanical symptoms.

McMurray Test

Patient lying supine
One hand of the examiner palpates the joint line (thumb on one side, fingers on the other)
The hand supports the limb at the sole of the foot and helps in the required movement maneuvers of the limb.
From a position of maximal flexion extend the knee with internal rotation of the tibia and varus stress.
Return the limb to the initial state of maximal flexion
From that position, extend the knee with external rotation of the tibia while applying valgus stress.
Test positive if there is reproduction of pain or other mechanical symptoms.

Apley’s test

Patient lying prone
Knee flexed to 90^o
The patient’s thigh is rooted to the table. (The examiner placing his/her knee on the patient’s thigh)
The examiner then laterally and medially rotates the tibia while applying traction. (Apleys’s Distraction Test) Pain at this level might indicate ligament or capsule damage.
The examiner then laterally and medially rotates the tibia this time applying compression. (Apley’s Grinding Test)
Test is positive if there is reproduction of pain and other mechanical signs. (especially if there is more pain with compression that with traction)

Collateral ligament injury Tests

Valgus and Varus Stress Tests

Patient supine
20o to 30o of knee flexion (reduce cruciate ligament involvement)
One hand of the examiner proximal to the knee (stabilize the limb), fingers palpating the joint line.
The other hand at the foot.
Apply abduction force at the foot. (Valgus stress test)
Apply Adduction force at the foot. (Varus stress test)
Tests are positive if there is opening of the joint line at the lateral side (varus test) or medial side (valgus test) and complaints of pain.

Type of injury	Tests
Collateral ligament sprain or rupture (LCL/ MCL)	Valgus and Varus stress tests
Cruciate ligament sprain or rupture (ACL/PCL)	Drawers tests (Anterior and posterior) Lachman test Pivot Shift test (instability)
Meniscal tear/derangement	Thessaly’s test Apley’s test McMurray test
Patella subluxation or dislocation	Patellar Apprehension test
Patellofemoral pain syndrome (chondromalacia patellae)	Clarke’s test aka patellar grind test
Detecting joint effusions	Ballottement test Patellar tap

References

American Family Physician – November 1, 2018 – Knee Pain in Adults and Adolescents: The Initial Evaluation