Knee Pain: Common Causes, Injuries & How Physical Therapy Can Help
Knee pain can show up in a lot of different ways. It may follow a hard cut or awkward position on the field, or gradually develop after increasing your running, training volume, or activity.
The knee is made up of bones, cartilage, ligaments, muscles, and tendons that all play a role in how we move and handle force. And because the knee works alongside the hip and ankle, understanding knee pain often means looking beyond just where it hurts.
In this article and video, Dr. Zach Baker, PT, DPT, SCS breaks down knee anatomy, common knee injuries, and what an effective physical therapy and rehabilitation program can look like.
The Structure of the Knee: More Than a Simple Hinge
The knee is often described as a hinge joint, built to bend and straighten while handling an incredible amount of force. It connects the femur (thigh bone) to the tibia and fibula (shin bones), with the patella (kneecap) sitting upfront to aid movement.
Between the femur and tibia sits the meniscus, a pair of cartilage pads (medial and lateral) that act as shock absorbers. Over time or through trauma, these can wear down or tear — one of the most common sources of knee discomfort.
The Ligaments: Stability in Motion
Supporting these bones are four critical ligaments that stabilize the joint:
- ACL (anterior cruciate ligament) and PCL (posterior cruciate ligament) – control forward and backward motion of the knee.
- MCL (medial collateral ligament) and LCL (lateral collateral ligament) – prevent excessive side-to-side movement.
These ligaments are your knee’s built-in stabilizers, working like emergency brakes during fast movements, sudden stops, or changes in direction. When pushed too far, partial or full tears can occur, requiring careful rehabilitation, and sometimes surgery, to restore stability.
The Muscles: Power and Protection
On the front of the thigh, the quadriceps connect through the patellar tendon to help straighten the knee. On the back, the hamstrings bend it. Below, the calf muscles (gastrocnemius and soleus) contribute to motion and help control extension.
When these muscles are strong and balanced, they absorb impact and reduce strain on the joint. Weakness or tightness, especially around the hips and ankles, can alter movement patterns and lead to knee pain.
Common Knee Injuries
Knee issues often fall into three categories:
- Bone-related injuries: Fractures or stress fractures from trauma or overuse.
- Cartilage injuries: Meniscus or articular cartilage damage from aging, repetitive stress, or twisting motions.
- Ligament and muscle injuries: Sprains, strains, and tears graded from mild (Grade 1) to complete ruptures (Grade 3).
Even minor injuries can worsen without proper recovery and movement retraining, making physical therapy essential for long-term joint health.
Why Are Knee Injuries Common in Field and Court Sports?
Running is only one demand placed on the knee during sports. Athletes are also accelerating, slowing down, cutting, pivoting, rotating, absorbing contact, and reacting to what is happening around them.
These movements can place greater demands on the ligaments, cartilage, muscles, and tendons around the knee, particularly when the body is asked to control more force or move into a position beyond what it can effectively manage.
That is also why strength, mobility, balance, and control at the hip and ankle matter. The knee doesn’t work in isolation, and preparing the entire lower body for the demands of sport can play an important role in performance and rehabilitation.
How Physical Therapy Restores Knee Function
At Rehab 2 Perform, our approach focuses on restoring mobility, strength, and control, not just reducing pain. A customized plan includes:
- Improving movement patterns and addressing weaknesses at the hip, ankle, and core
- Progressive strengthening to rebuild stability
- Functional training to help you return to the activities and sports you love
By understanding the anatomy and mechanics of your knee, you can take proactive steps toward lasting performance and prevention.
About Rehab 2 Perform
Rehab 2 Perform is a leading physical therapy and sports rehabilitation company dedicated to helping clients achieve optimal performance in their daily lives, whether they are athletes, weekend warriors, or individuals recovering from injury. With a team of highly skilled professionals, Rehab 2 Perform offers a personalized, evidence-based approach that emphasizes active rehabilitation and functional fitness. Find a Location near you, or Schedule Here.
Updated: September 2026.