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Knee Joint

Knee Joint

The knee joint is the most complicated joint in the body. It consists of three articulations– two tibiofemoral and one patellofemoral. As is characteristic of synovial joints, the knee joint has a thin articular capsule that partially surrounds this joint cavity. Additionally, several ligaments, muscles, and cartilaginous structures support the movement of the knee.
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Muscles that Move the Leg

Muscles that Move the Leg

The movement of the legs is facilitated by numerous muscles located within the anterior, medial, and posterior compartments of the thigh.
Anterior Compartment
The quadriceps femoris, the most visible muscle of the anterior compartment, is integral for leg extension and thigh flexion. It is formed by merging four distinct muscles — the vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris. The quadriceps tendon, a shared tendon of the four quadriceps muscles, is affixed...

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Bones of the Lower Limb: Femur and Patella

The femur is the body's longest and strongest bone spanning the thigh region. Its head articulates with the acetabulum of the hip bone to form the hip joint. A minor indentation on the medial side of the femoral head, called the fovea capitis, serves as the site of attachment for the ligament of the head of the femur. This weak ligament spans the femur and acetabulum and supports the hip joint. The narrowed region below the head is the neck of the femur. The inclination angle between the...

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A wedge is a simple machine that serves various purposes, such as adjusting the elevation of structural or mechanical parts, providing stability for heavy objects, and splitting a body into two parts. This versatile tool can amplify an applied force, making it easier to manipulate large or heavy objects.
Consider using a wedge to lift a heavy slab. Here, the wedge functions by converting the applied force into a much larger force directed almost perpendicular to the initial force. This...

Self-Locking Screw

Self-Locking Screw

A square-threaded screw jack is a mechanical device widely used for lifting heavy loads or applying considerable force. One of the key features that can make a screw jack more effective and reliable is its self-locking capability.
A square-threaded screw jack carrying a load is considered self-locking if the screw retains its position even after the moment applied to it is removed.

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In mechanical engineering, the stability of systems under various forces is critical for designing durable and efficient structures. One fundamental way to explore these concepts is by analyzing systems like two rods connected at a pivot point, O, with a torsional spring of spring constant k at the pivot point. This system is similar in appearance to a scissor jack used to change tires on a car. In this case, the arms of the linkage (equivalent to the rods in this system) are entirely vertical,...

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Related Experiment Video

Updated: Jul 4, 2025

Author Spotlight: Investigating the Mechanism of Action of Acupotomy in Treating Knee Osteoarthritis

Author Spotlight: Investigating the Mechanism of Action of Acupotomy in Treating Knee Osteoarthritis

Published on: October 20, 2023

The locked knee.

John-Henry Rhind¹, Haseeb Khawar², Mark Webb³

¹Department of Trauma and Orthopaedics, Epsom and St. Helier Hospital, Sutton, Surrey, UK.

British Journal of Hospital Medicine (London, England : 2005)

|February 1, 2024

Summary

This summary is machine-generated.

A locked knee is an emergency where the knee cannot fully extend. Prompt diagnosis and treatment, often involving magnetic resonance imaging and knee arthroscopy, are crucial for managing this condition.

Keywords:

Anterior cruciate ligament rupture Knee Knee arthroscopy Locked knee Meniscal tear Soft tissue knee

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Area of Science:

Orthopaedic Surgery
Emergency Medicine
Diagnostic Imaging

Background:

A locked knee is an orthopaedic emergency characterized by fixed flexion or a block to complete knee extension.
Causes include meniscal tears, anterior cruciate ligament ruptures, and loose bodies.
Prompt diagnosis and management are essential.

Purpose of the Study:

To provide an overview of the presentation, assessment, and management of the locked knee.
To educate core surgical, acute care common stem, and emergency medicine trainees.

Main Methods:

Review of common causes and diagnostic modalities.
Discussion of gold standard diagnostic imaging (magnetic resonance imaging) and management (knee arthroscopy).

Main Results:

Locked knee requires prompt attention.
Meniscal tears, ACL rupture, and loose bodies are frequent causes.
MRI and arthroscopy are key tools.

Conclusions:

Understanding the locked knee is vital for trainees.
Early recognition and intervention improve outcomes.