Anatomy and function of the knee

What makes up your knee?

The knee joint is the point at which the femur bone of the thigh meets the tibia bone of the lower leg. All the components of the knee - bones, cartilage, synovial membrane, ligaments, tendons and muscles - must work together properly for the knee to move smoothly.

Cartilage is a protective cushioning that keeps the bones from rubbing against one another.

In a healthy knee, a thin, smooth tissue liner called the synovial membrane releases a fluid that lubricates the knee, reducing friction as the bones move.


All information provided on this website is for information purposes only. Please see a healthcare professional for medical advice. If you are seeking this information in an emergency situation, please call 911 and seek emergency help.

All materials copyright © 2026 VoxMD.com, All Rights Reserved.

The information listed on this site is for informational and educational purposes and is not meant as medical advice. Every patient’s case is unique and each patient should follow his or her doctor’s specific instructions. Please discuss nutrition, medication and treatment options with your doctor to make sure you are getting the proper care for your particular situation.

◊ Trademark of Smith+Nephew. The information on this site is intended for US residents only © 2022 Smith+Nephew
Smith+Nephew Facebook Page | Follow Smith+Nephew on Twitter | Privacy & Cookies | Terms of Use

References

  1. Hall, et al. Unicompartmental knee arthroplasty (alias uni-knee): an overview with nursing implications. Orthopaedic Nursing. 2004;23(3):163-171. Accessed April 25, 2019.
    • Based on pre-surgical pain levels in UKA patients.
  2. Mayman DJ, Patel AR, Carroll KM. Hospital related clinical and economic outcomes of a bicruciate knee system in total knee arthroplasty patients. Poster presented at: ISPOR Symposium; May 19-23, 2018; Baltimore, Maryland, USA.
  3. Nodzo SR, Carroll KM, Mayman DJ. The Bicruciate Substituting Knee Design and Initial Experience. Techniques in Orthopaedics. 2018;33(1):37-41
    • Compared to non-JOURNEY II knees; Based on BCS evidence
  4. 1Short-term Range of Motion is Increased after TKA with an asymmetric bicruciatestabilized implant.AcceptedPoster Presentation, AAOS 2018 New Orleans. Kaitlin M. Carroll, Peter K. Sculco, Brian CMichaels,RichardL. Murphy, Seth A, Jerabek, David J. Mayman
  5. 2J Orthop. 2017 Jan 7;14(1):201- 206. doi: 10.1016/j.jor.2016.12.005. eCollection 2017. Bi-cruciate substituting total knee arthroplasty improved medio-lateral instability in mid-flexion range
  6.  In Vivo Kinematic Comparison of a Bicruciate Stabilized Total Knee Arthroplasty and the Normal Knee Using Fluoroscopy Trevor F. Grieco, MS a, *, Adrija Sharma, PhD a, Garett M. Dessinger, BS a, Harold E. Cates, MD b, Richard D. Komistek, PhD. The Journal of Arthroplasty, September 2017
  7. Testing concluded at 45 million cycles, ISO 14242-1 and 14243-3 define test completion at 5 million cycles. The results of laboratory wear simulation testing have not been proven to predict actual joint durability and performance in people. A reduction in wear alone may not result in improved joint durability and performance because other factors, such as bone structure, can affect joint durability and performance and cause medical conditions that may result in the need for additional surgery. These other factors were not studied as part of the testing.
  8. Iriuchishima T, Ryu K. Bicruciate substituting total knee arthroplasty improves stair climbing ability when compared with cruciate-retain or posterior stabilizing total knee arthroplasty. Indian J Orthop. 2019. doi:10.4103/ortho.IJOrtho_392_18.
  9. Smith JR, Picard F, Lonner J, et al. The accuracy of a robotically-controlled freehand sculpting tool for unicondylar knee arthroplasty. Congress of the International Society of Biomechanics. August 4-9, 2013. Natal, Brazil.
  10. Zardiackas, Lyle D., Kraay, Matthew J., Freese, Howard L, editors. Titanium, Niobium, Zirconium, and Tantalum for Medical and Surgical Applications ASTM special technical publication; 1471. Ann Arbor, MI: ASTM, Dec. 2005