Structure of the Knee
The knee joint is formed by three bones — the femur (thighbone), tibia (shinbone), and patella (kneecap) — and comprises three compartments: the medial (inner), lateral (outer), and patellofemoral. Unlike a simple hinge, the knee combines flexion-extension with rotational and translational movements, making it uniquely capable but also vulnerable to a variety of injuries.
Articular Cartilage
Smooth hyaline cartilage lines the bone surfaces, providing a near-frictionless bearing. Once damaged, it has a limited capacity for self-repair.
Menisci
Two C-shaped fibrocartilaginous discs (medial and lateral) act as shock absorbers, improve congruence, and distribute load across the joint surfaces.
Ligaments
The ACL and PCL control anterior-posterior stability; the MCL and LCL resist valgus and varus forces. Together they coordinate knee motion under load.
Common Symptoms & Their Significance
Accurate characterisation of knee symptoms guides the clinical assessment and helps narrow the diagnosis before imaging is obtained.
- Pain — location is key: medial (inner), lateral (outer), anterior (front of knee), or posterior (back of knee) pain each suggests different underlying pathology
- Swelling — effusion (fluid within the joint) after injury or activity suggests significant internal derangement; chronic effusion indicates ongoing joint irritation
- Locking — a joint that gets stuck in a flexed position, often due to a displaced meniscal tear or loose body
- Giving way — a sense of instability or the knee buckling, commonly associated with ligamentous injury or a loose body
- Clicking or catching — may indicate meniscal pathology, chondral damage, or patellofemoral maltracking
- Stiffness — particularly after rest or in the morning, often suggesting arthritis or inflammatory pathology
The Clinical Assessment
The knee assessment begins with a focused history, examining symptom onset, mechanism of any injury, and the impact on function and activity. Formal physical examination follows.
Inspection & Palpation
Assessment of alignment, swelling, muscle wasting, and point tenderness along joint lines, ligament insertions, and the patellofemoral joint.
Range of Motion & Strength
Active and passive flexion-extension, assessment of quadriceps and hamstring strength, and any signs of flexion contracture or extension lag.
Ligament & Meniscal Tests
Specific provocation tests such as the Lachman and anterior drawer test (ACL), McMurray and Thessaly tests (menisci), and valgus/varus stress testing (collateral ligaments).
Imaging
Weight-bearing X-rays assess joint space and alignment. MRI provides definitive imaging of soft tissue structures. Ultrasound is useful for tendon and ligament pathology.
Discuss Your Knee Condition
For a personalised assessment and treatment plan, contact Dr. Pirpiris’s rooms at Cabrini Medical Centre, Malvern.
📞 Call 03 9508 9600