Mr Paul Nicolai, FRCS (Tr & Orth)
Consultant Orthopaedic Surgeon
Specialist Knee Surgeon
Bury St Edmunds
Suffolk
United Kingdom
paul.nicolai@wsh.nhs.uk 01284 713774
Mr Paul Nicolai, FRCS (Tr & Orth)
Consultant Orthopaedic Surgeon
Specialist Knee Surgeon
Bury St Edmunds
Suffolk
United Kingdom
paul.nicolai@wsh.nhs.uk 01284 713774
The knee joint is made up from 3 bones: femur (thigh bone), tibia (shin bone) and patella (knee cap). All three bone surfaces are covered with a layer of joint cartilage, which forms the bearing surface. The lower end of the femur is round (looking side-on), and the top of the tibia is relatively flat, making the joint inherently unstable. It therefore relies on stabilisers, which can be divided in static (ligaments) and dynamic (muscles).
The main knee ligaments are the collateral ligaments on the inside (medial) and outside (lateral), and the cruciate ligaments (front or anterior and back or posterior) in the middle of the joint. The medial and lateral collateral ligaments provide side-to-side stability, whilst the anterior and posterior cruciate ligaments provide front-to-back and rotational stability. The main muscles groups are the quadriceps muscles (front of thigh), which straighten the knee, and the hamstring muscles at the back of the thigh, which bend the knee. Some calf muscles are attached above the knee, also helping with knee bending.
Between the femur and tibia there are 2 menisci (medial or inside and lateral or outside meniscus), which are also known as the footballer’s cartilage.
Clinically the knee can be divided in three compartments: inside (medial), outside (lateral) and knee cap (patello-femoral). In a normal situation when standing on two legs the body weight load passes through the middle of the knee joint. However, when walking two thirds of the body weight passes through the medial compartment.
The patello-femoral joint is loaded in particular with straightening of the knee (going up and down stairs, getting up from a chair or deep crouch etc). When walking about 3 times body weight passes through the knee joint, going up to 6 times when running. When jumping up to 7 times body weight passes through the patello-femoral joint.
Knee anatomy