The Knee: Anatomy and Injuries Sports Medicine Lesson 2: Understanding Athletic-Related Injuries to the Lower Extremity The Knee: Anatomy and Injuries Sports Medicine

Knee

Mechanics of the Knee Hinge Joint Knee movement Flexion Extension Slight Rotation Gliding Knee stability depends on ligaments, joint capsule, and muscles.

Joint Capsule

Bones of the Knee (Femur) Medial and lateral condyles (bumps or knobs) Medial condyle is longer than the lateral condyle. Trochlea – groove that receives the patella. Articular (joint) cartilage

Tibia Tibial plateau Tibial plateau (flat spot) has two shallow dips that match up with the medial and lateral condyles. Main weight bearing bone (95 – 97%).

Tibial Plateau

Patella Moves in the groove between the femoral condyles (bumps). Provides a better line of pull for the quadriceps muscles.

Fibula Main purpose is ligament and muscle attachment. Non – Weight bearing bone. Located on lateral side of the leg. Minimal knee function.

Ligaments of the Knee ACL PCL MCL LCL

Anterior Cruciate Ligament (ACL) Attachment: femur –lateral condyle. Attachment: Tibia – Anterior tibial plateau. Prevents excessive anterior movement and internal rotation of the tibia. Most likely to be injured!!

ACL Extension / Tight Flexion / Relaxed Very vascular Usually surgically replaced if torn.

Posterior Cruciate Ligament (PCL) Attachment: Femur -medial condyle. Tibia –tibial plateau. Prevents excessive posterior movement of the tibia on the femur. Prevents hyperextension of the knee

Medial Collateral Ligament (MCL) Attachment: Femur – superior epicondyle. Tibia – Medial aspect / medial meniscus. Resists valgus forces. (inward bending) Resists external rotation of the tibia.

Lateral Collateral Ligament (LCL) Attachment: Femur – lateral epicondyle. Fibula: Fibular head Resists varus forces (outward bending) which causes “bowed legs”

Meniscus Medial (C- shape) and lateral (O-shape) meniscus. Located on tibial plateau. Primary function – shock absorber. Increase surface contact. Helps stabilize knee

Meniscus

Bursa's of the Knee Bursa’s are fluid filled sac’s . Reduce friction between anatomical structures. Two dozen bursa’s within the knee. Prepatellar most often injured.

Bursa's of the Knee

Muscles of the Knee

Quadricep Muscle Group

Quadriceps Extensors of the knee. Stabilizers of the knee. Made up of 4 muscles (quad = four) Vastus medialis (VMO) – important for patellar tracking. Vastus intermedialis Vastus Lateralis Rectus femoris – Knee extension / Hip flexion.

Patellar Tendon Patellar Tendon –tendon shared by the quadriceps muscle group. The patella is located in it.

Hamstring Muscle Group

Hamstrings Flexors of the knee. Extensors of the hip. Prevents anterior tibial movement / Aids ACL.

IT - Band Lateral side of leg. Important in the knee Assist LCL in the lateral stability of the knee.

IT band in need of “rolling IT band in need of “rolling.” Process by which we stretch and loosen up the ligament. Inflammation of the IT band causes pain in the lateral knee.

I-T Band Friction

Meniscus Injuries Mechanism – Compression and rotation femur / tibia. Can be associated with ligament injury (MCL).

Meniscus injuries Signs & Symptoms - Joint Swelling - Clicking or locking. - Loss of ROM (range of motion) - Diagnosis is often difficult.

Meniscus MRI

Treatment Surgical treatment - Procedure depends on location and severity of tear. - Resection (Total removal of tear) - Stitch or tack.

Non Surgical Treatment - Indicated only for minor tears. - RICE (Control Swelling) - Maintain ROM / Strength - Non surgical treatment can result in further damage

ACL Injuries Common in sports. Mechanism – External rotation of tibia, knee in valgus position, foot fixed. Signs & Symptoms Feeling pop Knee feels unstable Joint swelling

Non Surgical Treatment RICE (Control Swelling) Immobilizer / Crutches Refer to physician Rehabilitation (Strengthening & ROM)

MRI of ACL NORMAL ACL ACL TEAR

Surgical Treatment Arthroscopic surgery Various grafts can be used for repair. Patellar tendon (Autograft) Hamstring (semitendinosus / Gracillis) Cadaver (Allograft) Surgical Treatment

Patellar Tendon (autograft)

PCL Injuries Injured less frequent Mechanism: - Fall on anterior aspect of bent knee with foot plantar flexed. - Hyperextension

MCL / LCL Injuries MCL injuries are usually caused by a lateral to medial blow to the knee. Also known as a valgus force. LCL injuries are usually caused by medial to lateral blow to the knee. Also known as a varus force.

MCL Injuries Mechanism of Injury - direct blow from the lateral side (Valgus Stress) - severe rotation of the tibia - can be a combination of both

MRI OF MCL TEAR

MCL Sprains 1st degree - ligamentous fibers are stretched - joint is stable during valgus stress test - little or no joint effusion - may be some joint stiffness and medial joint line tenderness - almost full range of motion

MCL Sprains 2nd degree sprain - partial tear of the ligament - slight to moderate laxity during valgus stress test - there is little joint effusion - moderate to severe joint stiffness with loss of ROM

MCL Sprains 3rd degree sprain - Complete tear - severe laxity revealed with valgus stress test - moderate joint effusion - loss of ROM

Treatment of Knee Sprains 1st degree – RICE, Rehab to increase strength, ROM. 2nd degree – RICE, Immobilize, Crutch, 24 hours. Re-evaluate. Refer to physician 3rd degree – RICE, Immobilize, Crutch. Refer to physician

LCL Injuries Not very common in athletics. Occurs by a medial blow to knee which produces a varus stress

Patellar Dislocation

Knee Dislocation

Knee Dislocation

Prevention of Knee Injuries To avoid injuries to the knee, the athlete must be as highly conditioned as possible, which means total body conditioning that includes strength, flexibility, cardiovascular and muscle endurance, agility, speed and balance. THE MUSCLES around the knee MUST be strong and flexible.

Prevention of Knee Injuries Athletes participating in a particular sport should acquire a strength ratio between the quadriceps and hamstring muscle groups. For example: the hamstring muscles of football players should have 60 to 70 percent of the strength of the quadriceps muscles. The gastrocnemius muscle should also be strengthened to help stabilize the knee. Although maximizing muscle strength may prevent some injuries, it fails to prevent twisting injuries.

Prevention of Knee Injuries Shoe Type: Cleat Length Astro Turf shoes: more grip=more injuries Sneakers are good for artificial surfaces

Functional and Prophylactic Knee Braces Functional Knee Braces are used to protect grade 1 and 2 sprains of the ACL and MCL, and reconstructed ACL knees. Most of them are bilateral knee braces, meaning there is a hinge on both sides of the brace. These braces have an important part within the athletic community. They will also give the athlete confidence while playing.

Knee Injury Treatments Side Leg Raises

Knee Injury Treatments Side Leg Raises

Knee Injury Treatments Terminal Knee Extensions

Knee Injury Treatments Step Ups

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