Mid-Week MOT: Knee Series.......Part One
The knee is the strongest and largest joint in the body.
Together, the knees support almost your whole body weight, which is magnified many times when running and jumping. As such, the joint has many supporting tissues and powerful muscles crossing it, allowing mobility whilst maintaining stability.
We have all had, or will have, an episode of knee pain at least once in our lives and there are many causes. This article will look at the anatomy of the knee and some common conditions that cause pain, continuing with more next week.
In simple terms, the knee is a hinged synovial joint which means it is contained within a capsule that is nourished by synovial fluid, keeping the surfaces lubricated and reducing friction. The joint design affords flexion, extension and some rotation of the lower leg.
The thigh bone (femur), meets the shin bone (tibia) and sandwiched between the bone ends is a layer of cartilage called mensicii that run in two halves on the inside and outside edges. The ends of the bones are coated in a thin layer of hyaline cartilage which also ensures smooth, energy efficient movement.
In the middle of the joint, the two cruciate (crossing) ligaments prevent excessive forward or backward movement of the tibia on the femur. On either side of the joint are the lateral and medial collateral ligaments which further add to the joint's stability.
The second part of the knee joint is the patella or knee cap and its adherence in a bony channel to the front of the femur end whilst sitting encased in its own tendon - an extension of the quadriceps muscles - and attaching on the front of the tibia about 2" below.
The patella provides leverage to magnify the strength of the muscles controlling extension of the leg, as well as being a spacer for the quads tendon and its path through the ends of the femur. The patella has a covering of cartilage on its rear and forms the patellofemoral joint.
See the diagram below...
When it all goes wrong:
So if you consider the number of structures that make up the knee joint, it is easy to imagine how it can easily become injured or prone to disease.
Because of this, the simplest way to categorise knee pain is to separate it into acute injury or more chronic disease.
This week we will concentrate on the acute injuries, following up next week with chronic problems.
Firstly though, it is prudent to mention the red flag symptoms which should be considered whether the injury or illness is acute or chronic. These are symptoms that indicate serious problems and should be investigated sooner rather than later.
Red Flag Symptoms:
Unable to weight bear and/or unstable giving way, history of traumatic injury, popping or crunching sounds, accompanying painful urinary symptoms , heat or swelling around the joint, decreased range of movement, fever, malaise, recent respiratory or gastrointestinal infection. These are all indicative of requiring further investigation by a doctor and the list is by no means exhaustive.
When assessing acute knee problems, we look at the mechanism of injury such as twisting, extending, direct force or landing and the history of the pain. This, followed by observation and examination, should tell us whether hospital treatment is required.
Meniscal injuries are common, as the cartilage can become detached or partially torn. Pain at the joint line, measured just below the bottom edge of the patella, is common with some swelling and tenderness over the area.
The collateral ligaments inside and outside the knee can sprain or rupture from excessive rotational movements, leading to an unstable joint.
When a footballer kicks the ground instead of the ball, there is a very good chance that the cruciate ligament (anterior) can become ruptured or stretched, as the femur keeps moving forward on the tibia as the foot implants into the ground.
A situation called the "unhappy triad" is a common injury in skiers, rugby and football players and occurs when the foot is planted and the knee twisted, injuring the anterior cruciate ligament, the medial collateral ligament and the medial meniscus. The injury often requires surgical repair and a long recovery.
Of course all the bones of the joint can fracture too due to direct or indirect forces and this would normally lead to swelling, deformity, bruising and inability to weight bear.
The patella is particularly prone to dislocating, this occuring more often in adolescent females.
Acute conditions which are not due to direct injury can include osteomyelitis (bacterial infection in the bone from a wound), septic arthritis (infection causing joint degeneration) and reactive arthritis (from a previous systemic infection such as respiratory or urinary that causes an inflammatory process).
Gout can also develop very quickly and be incredibly painful, usually affecting one side. This is a build up of uric acid crystals in the joint, which are shaped like shards of glass and feel exactly the same! Gout is a treatable condition but often reoccurs, attacking different joints such as the big toe and knee.
A lot of knee injuries have similar signs and symptoms and so it is difficult to diagnose exactly what is wrong without some form of imaging.
Plain x-rays and CT scans are good for identifying bony injury, while ultrasound and MRI scanning are better for looking at soft tissue damage. Sometimes blood tests are required to rule out underlying pathology.
Immediate first aid after an injury should include rest, ice, compression and elevation, followed by an examination by a medical professional. If in doubt, treat for the worst, such as fracture and go to the A&E department.
Obviously, accidents are often not preventable but you can minimise your risk by making sure you warm up sufficiently before exercise and stretch after, wear good shoes appropriate to your chosen activity and keep yourself at normal weight.
So that just about covers the main injuries and acute conditions that may be encountered. Next week we will look at chronic conditions such as arthritis and tendonitis.
As always, for osteopathy in High Wycombe and beyond, call Lucy from OsteoFusion on 07833 321604 or visit www.osteofusion.co.uk.
Thanks for reading.
References: Brukner, P. & Khan, K. (2011) Clinical Sports Medicine. (4th Ed) McGraw-Hill, Australia.