Knee Joint Anatomy: A Comprehensive Guide

Introduction

In human body the most complex and the largest joint is the knee joint. This complex knee joint structure is made up of muscles, four bones and ligaments complex web. Knee joint is a bi-condylar (hinge) form of synovial joint, due to this it can perform flexion and extension and little degree of medial and lateral rotation. Knee joint is the most stressed joint of the body.

Anatomy

Articulating surfaces

In knee joint the femur, tibia and patella articulates through 2 joints which are patellofemoral and tibiofemoral joints. Articular cartilage helps to reduce friction forces between these three bones because they are very frim and smooth.

The articulation between the patella and the femur’s anterior and posterior portion form the

patellofemoral joint. The patella is located in the intercondylar groove of femur.

Similar to this, the articulation between medial and lateral condyles of femur and tibia’s condyle form a tibiofemoral joint. Which is the weight bearing joint of the knee.

The tibiofibular joint is also present there, which is formed between tibia and fibula. Although this joint is not involved directly in knee joint, but it is important for the attachment of muscles and ligaments.

Menisci

In knee joint medial and lateral menisci are present which crescent shaped fibrocartilage rings are. The surface of each menisci is concave superiorly and flat inferiorly providing the surfaces to femoral condyles and tibial plateau respectively. The both menisci are connected at both ends of tibia’s intercondylar region. The menisci has the 2 main functions.

1. The tibiofemoral joint stability is increased because menisci deepens the surface of tibia.
   1. Menisci serve as shock absorbers due to increase in area of contact and improve the weight distribution across the joint.

The meniscal fibers arrangement distributes axial loads radially, which decreases the hyaline cartilage’s wear. Which is important during walking or running, because during walk knee stresses can increase to 1-2 times and 3–4 times the body weight during running.

The medial meniscus are less mobile because they are fixed with the joint capsule and medical collateral ligament. Therefore due to damage of medial collateral ligament, the medial meniscus tears occurs frequently.

The lateral meniscus is more mobile and smaller than the medial meniscus because it does not have any additional attachments.

The both menisci’s are fully vascularized during 1^st year of life. But after human starts weight bearing the vascularity in meniscus decreases in the red zone (outer 3^rd part). While the synovial fluid provides nutrition to the white zone (non-vascularized part) through diffusion.

Also Read: Best Workout Split for Muscle Gain

Bursa

There are 4 synovial fluid filled sacs are present between the moving parts of knee joint known as bursa. Which are semimembranosus, suprapatellar, infrapatellar and prepatellar bursa.

The function of bursas to decrease wear and tear on those knee joint structures.

Joint Capsule

Joint capsule enhance the joint stability. It limits the joint movements and provide the passive joint stability and it has proprioceptive nerve endings due to which active joint stability increases.

Joint capsule has a membrane called synovial membrane and this membrane produces synovial fluid which provide nourishment to the surrounding structures of knee joint.

Ligaments

Each ligament of knee joint provide the optimal stability to knee joint and each has particular function. Knee has two main types of ligaments.

Collateral Ligaments

They are present on the both opposite (medial and lateral) sides of knee in strap-like form.

• Medial collateral ligament (MCL): This ligament attached proximally to the medial epicondyle of the femur and distally with the medial condyle of tibia. It helps to prevent excessive medial movement of knee joint. It resists the valgus force (force from the outside of knee) more effectively during full knee extension (closed packed position) because there is more laxity in ligament during knee flexion (open packed position).
  • Lateral collateral ligament (LCL): It is an extracapsular ligament. This ligament is attached with the lateral epicondyle of femur proximally and with lateral side of fibula head distally. It helps to prevent excessive lateral movement of knee joint. It resists the varus force more effectively.

Cruciate Ligaments

Tibia and fibula are connected by the 2 cruciate ligaments and they create an X when they cross each other in knee joint.

• Anterior cruciate ligament (ACL): Anterior dislocation of tibia on femur is prevented through this ligament. It is attached tibia’s anterior intercondylar region with femur’s intercondylar fossa.

• Posterior Cruciate Ligament (PCL): This ligament attach the tibia’s posterior intercondylar region with femur’s anteromedial condyle. PCL helps to stops tibia from dislocating on femur posteriorly.

Blood and Nerve Supply

The main Arteries are involved in the knee joint are:

• Popliteal artery
  • Femoral artery

The Nerves in the knee joint are:

• Sciatic nerve
  • Femoral nerve
  • Peroneal nerve
  • Tibial nerve

Muscles and Functions

These 4 movements of knee joint performed by the following muscles.

FLEXION:

• Hamstrings (Biceps femoris, Semitendinosus, Semimembranosus)
  • Popliteus
  • Sartorius
  • Gracilis

EXTENSION:

• Quadriceps femoris (vastus lateralis, rectus femoris, vastus intermedius and vastus medialis)
• Tensor fasciae latae ( weak Extensor)

Medial Rotation:

• Sartorius
• popliteus
• gracilis
• semitendinosus
• Semimembranosus

Lateral Rotation:

• Biceps femoris

Common Injuries and Conditions of Knee Joint

• Knee osteoarthritis
  • Rheumatoid arthritis
  • Osteoporosis
  • Meniscus tear/lesions
  • Baker’s cyst
  • Gout
  • Dislocations
  • Unhappy triad
  • Patellofemoral pain syndrome (PAS)
  • Medial collateral ligament (MCL) injury
  • Lateral collateral ligament (LCL) injury
  • Posterior cruciate ligament (PCL) injury
  • Anterior cruciate ligament (ACL) injury
  • Genu-recurvatum
  • Tibial fractures
  • Femur fractures
  • Patellar fractures
  • Knee bursitis
  • Pre-patellar Bursitis
  • Quadriceps muscle contusion
  • Hamstring strain
  • Quadriceps muscle strain
  • Plica syndrome
  • Sinding Larsen Johansson syndrome
  • Iliotibial band syndrome
  • Osgood-Schlitter’s disease
  • Popliteus tendinitis
  • Patellar tendinitis
  • Tibial plateau fractures
  • Articular cartilage lesions
  • Chondromalacia patellae
  • Osteochondritis dissecans of the knee
  • Quadriceps muscle strain
  • Quadriceps muscle contusion
  • Popliteus strain
  • Semimembranosus tendinopathy

Common Symptoms of Knee Joint Disorder

Following are the symptoms of knee joint disorder that you need to contact medical professionals or a physiotherapist:

• Severe pain around knee joint.
• Popping sound from knee joint during walking, stair climbing and moving the leg.
• Unable to bear weight on knee
• Stiffness around knee joint
• Swelling
• Warmth in contact
• Redness
• Weakness
• Unable to straight and bend knee joint
• Difficulty in climbing up the stairs
• Knee joint locking and buckling
• Even after three days of at-home therapy, your pain persists.
• Below the aching knee, you get calf discomfort, numbness, swelling, tingling, or bluish discoloration.
• Knee has a malformation or deformity, for example Varus or Valgus deformity

Knee Pain Treatment in Lahore

Visit us at Physio Resource if you are unable to enjoy life fully due to knee pain. Knee is the most important joint of human body which help us move and walk. Our physiotherapist will find therapies that maintain your knees strong, healthy, and functioning as they should as well as assist you in understanding what’s happening inside your knee joint. They are dedicated to provide everyone with high-quality physiotherapy care through state-of-the-art facilities and highly qualified professionals. So scheduled your appointment now with one of our best physiotherapist in Lahore.

Contact us

Phone No: 0304-4283442

Address: 14-Ghalib Rd, Block D1, Gullberg III, Lahore