The knee is a complex joint that is supported by various tendons and ligaments. The knee plays a very important role in helping you walk, run, and be active.
The knee plays a very important role in helping you walk, run, and be active. The three bones that make up the knee joint are the femur (thigh bone), tibia (shin bone) and patella (knee cap). The fibula is a 4th bone that primarily serves as an attachment point for ligaments and tendons, but does not make up the knee joint. It forms a small joint with the top of the shin bone called the tib-fib joint.
There are several soft tissue structures that work together to support the knee joint. Each of these structures has the potential to be injured and can lead to a pathology that may require treatment.
- Articular cartilage is a very specialized tissue that lines the ends of the bones that form the joint and creates a smooth gliding surface. The cartilage is normally a few millimeters thick on each end of the bone. The cartilage can be damaged in a localized area or more diffusely.
- When the cartilage becomes damaged in a localized area, the underlying bone is also usually affected. This is called an osteochondral defect
- Arthritis is the more diffuse breakdown of the articular cartilage. Arthritis is a continuum of cartilage breakdown and can be mild, moderate, or severe.
- There are four main ligaments in the knee: one on each side of the knee, the medial and lateral collateral ligaments or MCL and LCL, and two in the center of the knee - the anterior and posterior cruciate ligaments, or ACL and PCL.
All of the ligaments contribute to stability with side-to-side motion, but the ACL and PCL stabilize the front to back stability of the knee.
The menisci are two cartilage structures that sit between the femur and tibia on each side of the knee. The medial meniscus is on the inside and lateral meniscus is on the outside of the knee. Meniscus means “little moon” in greek. These two crescent moon-shaped structures cushion the cartilage that covers the ends of the femur and tibia and are critical for preserving cartilage health.
With age, the water content inside the meniscus goes down, which makes the menisci more brittle. Instead of stretching when the knee is twisted or stretched, the meniscus can break causing a tear.
Meniscus tears also commonly occur in conjunction with ACL tears.
The four main muscles in the front of the thigh are called the quadriceps muscles. These muscles coalesce to form the quadriceps tendon that attaches to the top of the patella. The patellar tendon attaches the bottom of the patella to the tibia at a point on the tibia called the tibial tubercle.
The iliotibial (or IT) band is a wide tendon that is formed from the tensor fascia lata and the gluteus maximus muscles at the hip. The IT band runs along the outside of the thigh and attaches to the top of the tibia just below the knee joint.
Bursas are thin sacks that normally contain a small amount of fluid. Bursas created a gliding surface for skin and/or tendons as they glide over or under bony prominences in the body. The two main bursas in the knee are the prepatellar bursa, which is directly above the knee cap, and the pes bursa, which sits above three of the hamstring tendons that attach to the tibia at the anteromedial knee.
The capsule is a thin connective tissue that surrounds the joint, providing some stabilization to the joint.
A synovial membrane lines the inner surface of the capsule and produces synovial fluid to lubricate the joint. It also provides nutrition to the cartilage. The main component of synovial fluid is hyaluronic acid, which is a large molecule that absorbs water and improves the lubrication of the joint.
Initial Goals (1-4 weeks):
- Pain reduction
- Reduce inflammation through Manual Therapy and Home Exercises
- Improve range of motion
- Restore functional mobility such as home mobility and sleeping through the night
Secondary/Progressed Goals (4-8 weeks):
- Restore full range of motion
- Normalize community distance walking
- Return to work duty function
Tertiary Goals (Injury dependent as educated by your surgeon and physical therapist):
- Return to Sport/Work out as indicated (ACL restricted to 6 months)
- Restore full strength in affected knee
- Jogging/running assessment
Long Term Goals:
- Return to impact/sport drills
- Jogging/running assessment (6 months post-ACL repair)