Knee Assessment: Purpose, Anatomy, and Comprehensive Protocol

How do you assess a knee?

Assessing the knee involves a systematic approach combining subjective history, objective observation, palpation, range of motion, strength testing, and functional movement analysis to identify potential limitations, imbalances, or areas of concern relevant to fitness and movement, rather than for medical diagnosis.

Understanding the Purpose of Knee Assessment

A thorough knee assessment, particularly within a fitness or performance context, serves several critical functions. It helps identify predispositions to injury, uncover existing compensations or weaknesses, monitor rehabilitation progress, and ultimately, guide the development of safe and effective exercise programs. Unlike a medical diagnostic assessment performed by a physician or physical therapist, a fitness-oriented knee assessment focuses on functional capacity, movement patterns, and identifying biomechanical inefficiencies that can impact performance or contribute to pain.

Essential Knee Anatomy for Assessment

A foundational understanding of knee anatomy is paramount for effective assessment. The knee is a complex hinge joint, primarily formed by the articulation of the femur (thigh bone), tibia (shin bone), and patella (kneecap).

• Bones: Femur, tibia, patella, and fibula (though not part of the joint, provides muscle attachments).
• Ligaments: Provide stability. Key ligaments include the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL).
• Menisci: Two C-shaped cartilaginous pads (medial and lateral meniscus) that act as shock absorbers and help distribute weight within the joint.
• Muscles: Surrounding muscles provide dynamic stability and facilitate movement. Key groups include the quadriceps (knee extension), hamstrings (knee flexion), and calf muscles (ankle plantarflexion, minor knee flexion).
• Bursae: Fluid-filled sacs that reduce friction between bones, tendons, and muscles.

The Comprehensive Knee Assessment Protocol

A systematic knee assessment should follow a logical progression, starting with the least invasive methods and moving towards more specific evaluations.

Subjective History and Interview

Always begin by gathering comprehensive information from the individual. This is often the most critical step, providing context for all subsequent objective findings.

• Current Symptoms: Location, type (sharp, dull, aching), intensity (scale of 0-10), onset (sudden vs. gradual), duration, and aggravating/alleviating factors.
• Mechanism of Injury (if applicable): How did the injury occur? Was there a specific event (e.g., twisting, direct impact)?
• Past Medical History: Previous knee injuries, surgeries, arthritis, or other relevant medical conditions.
• Activity Level and Goals: What activities do they participate in? What are their fitness goals? How does the knee condition impact these?
• Daily Activities: How does the knee feel during walking, climbing stairs, sitting, or standing?

Observation and Visual Inspection

Observe the individual both statically (standing, sitting) and dynamically (walking, squatting).

• Static Posture: Look for general alignment from anterior, posterior, and lateral views. Note any:
  • Swelling: Generalized or localized effusion.
  • Muscle Atrophy/Hypertrophy: Especially quadriceps (vastus medialis obliquus) and hamstrings asymmetry.
  • Skin Changes: Redness, bruising, scars.
  • Patellar Position: Is it tracking centrally, or is there evidence of lateral deviation?
  • Lower Extremity Alignment: Genu valgum (knock-knees) or genu varum (bow-legged), tibial torsion.
• Dynamic Observation:
  • Gait Analysis: Observe walking pattern for limping, knee hyperextension, or reduced knee flexion.
  • Functional Movements: Squats, lunges, step-ups. Look for:
    • Knee Valgus Collapse: Knees collapsing inward during a squat or landing.
    • Patellar Tracking: Does the kneecap move smoothly or deviate?
    • Hip and Ankle Compensation: Are other joints compensating for knee issues?

Palpation

Gently feel around the knee joint to identify areas of tenderness, warmth, swelling, or structural abnormalities.

• Bony Landmarks: Patella, tibial tuberosity, femoral condyles, fibular head.
• Joint Line: Medial and lateral joint lines (often tender with meniscal or collateral ligament issues).
• Tendons: Patellar tendon, quadriceps tendon, hamstring tendons (pes anserine).
• Muscle Bellies: Quadriceps, hamstrings, gastrocnemius.
• Bursae: Prepatellar, infrapatellar.

Range of Motion (ROM) Assessment

Assess both active (individual moves the joint) and passive (examiner moves the joint) range of motion.

• Knee Flexion: Normal is typically 135-150 degrees.
• Knee Extension: Normal is 0 degrees (full extension) to slight hyperextension (up to 5-10 degrees).
• End Feels: Note the quality of resistance at the end of the range (e.g., firm, soft, empty).
• Goniometry: Use a goniometer for objective measurement and tracking progress.

Strength Assessment

Evaluate the strength of key muscle groups surrounding the knee.

• Manual Muscle Testing (MMT): Assess individual muscle strength (e.g., quadriceps, hamstrings, glutes) against resistance.
• Functional Strength Tests:
  • Single-Leg Squat: Assesses unilateral strength, balance, and control.
  • Step-Up/Step-Down: Evaluates concentric and eccentric control.
  • Wall Squat: Assesses isometric quadriceps endurance.

Balance and Proprioception

The knee relies heavily on proprioceptive input for stability.

• Single-Leg Stance: Time how long an individual can stand on one leg, eyes open and closed.
• Balance Error Scoring System (BESS): A standardized balance test.
• Star Excursion Balance Test (SEBT): Assesses dynamic balance and neuromuscular control.

Functional Movement Patterns

Beyond isolated movements, observe how the knee functions during more complex, sport-specific or daily activities.

• Squat Variations: Goblet squat, overhead squat.
• Lunge Variations: Forward, reverse, lateral.
• Jumping and Landing Mechanics: Observe for soft landings, knee alignment, and absorption.
• Agility Drills: Shuttles, cones.

Interpreting Your Findings

After collecting all assessment data, synthesize the information to form a comprehensive picture. Look for patterns, asymmetries, and deviations from optimal mechanics.

• Correlate Subjective with Objective: Do the areas of pain reported match objective findings like tenderness or restricted ROM?
• Identify Weaknesses/Imbalances: Is one side significantly weaker? Are the quadriceps much stronger than the hamstrings?
• Observe Compensations: Are other joints (hip, ankle) moving abnormally to compensate for knee limitations?
• Recognize Red Flags: Be alert for signs that warrant immediate medical referral (see below).

Based on your interpretation, you can then tailor exercise programming to address identified issues, focusing on strengthening weak muscles, improving flexibility, enhancing motor control, and correcting faulty movement patterns.

When to Refer: Scope of Practice and Red Flags

As a fitness professional or enthusiast, it is crucial to understand the limitations of a non-medical assessment. Your role is to identify potential issues and guide exercise, not diagnose or treat medical conditions.

Refer immediately to a medical professional (physician, physical therapist) if you encounter any of the following "red flags":

• Acute trauma with severe pain and inability to bear weight.
• Significant swelling or deformity.
• Clicking, locking, or giving way of the knee joint.
• Severe pain that does not subside with rest.
• Signs of infection: Redness, warmth, fever, pus.
• Numbness, tingling, or weakness in the lower leg or foot.
• Suspected fracture or ligamentous rupture.
• Pain that is worsening despite appropriate modifications or rest.
• Any symptom that falls outside your scope of practice or for which you are unsure.

Conclusion: A Holistic Approach to Knee Health

Assessing the knee is a dynamic and ongoing process. It provides invaluable insights into an individual's biomechanics, helping to prevent injuries, optimize performance, and promote long-term knee health. By employing a systematic and evidence-based approach, fitness professionals and educated enthusiasts can make informed decisions regarding exercise programming, always prioritizing safety and knowing when to refer to a qualified medical professional. Remember, the knee does not function in isolation; a holistic assessment considering the entire kinetic chain (foot, ankle, hip, core) will yield the most comprehensive understanding of its function and dysfunction.