The Knee complex

The knee is extremely complicated with many potential structures to go wrong. This article will detail some of the main things that can happen to your knee. 

Patella femoral pain syndrome (kneecap)

—Anterior knee pain (pain at the front of your knee)

—Aggravating factors:  
—flexion (bending) activities/sitting/sustained flexion (bending)
—Trauma 
—Common between the ages of 20-40 
—Caused by mechanical/chemical mechanisms  
Believed muscle imbalance/ timing can cause it

Osteoarthritis

—Common in the over 40's
—Medial (inside) more than the lateral (outside) compartment 
—Instability, buckling or giving way 
—Laxity of ligaments 
—Malalignment,
Stiffness  (usually less than 1 hour in the morning)
—X-ray shows degenerative changes

 Medial collateral ligament (MCL)

—MCL:

—most common injury in the knee 

—Younger age group due to sport and exercise related cause 

—Medial  (inside) joint pain/tenderness 

—No locking

—Swelling usually occurs within the first 24 hours of injury

Anterior cruciate ligament (ACL)

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—Usually a deceleration injury often non contact or hyperextension (bending the knee backwards)
contact
—Haemarthrosis ( within 2 hours)  (bleeding in the joint)
—Popping noise at time (can be quite loud)
Inability to continue or weight bear
Inability to continue   — Giving way & instability afterwards

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Plica

—Medial retropatellar pain: 

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Insidious onset (no reason) 

—Full Range of Movement 

—Pain extreme flexion (bending) 

—Plica thickened

—Palpation is the easiest way to diagnose

Patella Tendinopathy

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Males more than females 

—Athletic population  are the most common

—Often Bilateral 

—Previous Patella Femoral Pain Syndrome/pathology/osgood slaters 

—Tendon insertion pain

—18-30  are the most common ages
—Impact is the cause although this is affected by multiple factors

Osteochondritis dissecans (OD) / Osgood Schlatters (OS)

—OD: lateral outside part of the Medial Femoral Condyle 

—OS: tibial tuberosity (bump below knee on upper shin) 

—Adolescents only 

—Men more than Female 

—Previous history can be a factor

Meniscal injuries (cartilage)

—Medial:Lateral ratio of 5:1 

—80% are posterior (back)

—Caused by a Flexion/rotation injury under a weight bearing load

—Locking/catching/block to extension (unable to lock the knee out straight) 

—Joint line tenderness : In 50% of cases

—Pain in extremes Flexion/Extension

Hoffa's Fat pad

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The fat pad stabilises the patella at the extremes of knee motion & alters knee biomechanics (Bohnsack et al 2004)

The fat pad is an under-diagnosed, poorly recognised source of patellofemoral pain, It is frequently confused with patellar tendinosis.

Individuals with fat pad symptoms have poor inner range quadriceps control & often walk with a flexed knee to avoid irritating the fat pad. 

—Aggravated by standing

— Infrapatellar (below the kneecap) 

—Part of the patella femoral joint 

—Secondary more than primary in cause 

—Extension pain (locking the knee)

So as you can see the knee is complicated and this article doesn't cover all potential conditions that cause knee pain. This is why having your knee fully assessed by a Physiotherapist is important.

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