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Piriformis syndrome

Piriformis syndrome (PS) is a neuromuscular condition where the piriformis muscle – one of the deep gluteal muscles – presses on and compresses the sciatic nerve causing pain, tingling and numbness in the buttock area, and down the path of sciatic nerve to the thigh and leg. Sciatic nerve runs under the piriformis muscle (Fig. 1) and may be irritated when the muscle is too tight or shortened due to spasms. Piriformis syndrome is to be differentiated from sciatica which shows similar symptoms but has different causes.

Fig. 1 : Piriformis syndrome. Posterior view of the pelvis showing location of piriformis muscle and sciatic nerve. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Diagnosis is difficult as it produces similar symptoms as sciatica and is commonly done by exclusion of sciatica caused by compression of sciatic nerve roots by a herniated disc.

Fig. 2 : Sciatica caused by compression of spinal nerve roots by a herniated disc. Lateral view of the lumbar spine. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Causes and Risk factors

– Anatomical abnormality of the nerve/muscle relation. Some people are more likely to get PS than others.

– Tightness or spasm of piriformis muscle due to overuse injury. This commonly happens in sport activities that put pressure on the piriformis muscle such as bicycling, running without proper stretching, or any activity that involves repeated movements of the leg performed in sitting position.

Treatment

– Conservative treatment includes stretching exercises, massage, avoidance of causative activities.

– Physical therapy that strengthens the gluteus maximus, gluteus medius, and biceps femoris is usually recommended to reduce strain on the piriformis muscle.

– Relief of symptoms may be achieved with anti-inflammatory drugs or muscle relaxants.

Glaucoma

Below is a narrated animation about glaucoma development and types of glaucoma. Click here to license this video and/or other eye and vision related videos on Alila Medical Media website.

Glaucoma is a group of eye diseases in which the optic nerve is damaged leading to irreversible loss of vision. In most cases, this damage is due to an increased pressure within the eye – elevated intraocular pressure.

How glaucoma develops

The eye produces a fluid called aqueous humor which is secreted by the ciliary body into the posterior chamber, a space between the iris and the lens. It then flows through the pupil into the anterior chamber between the iris and the cornea. From here, it is drained through a sponge-like structure located at the base of the iris called the trabecular meshwork and leaves the eye. In a healthy eye, the rate of secretion balances the rate of drainage.

In people with glaucoma, this drainage canal is partially or completely blocked. Fluid builds up in the chambers and this increases pressure within the eye. The pressure drives the lens back and presses on the vitreous body which in turn compresses and damages the blood vessels and nerve fibers running at the back of the eye. These damaged fibers result in patches of vision loss and if left untreated may lead to total blindness.

For eye anatomy basics click here.

Click here to see an animation of glaucoma progression on Alila Medical Media website where the video is also available for licensing.

Fig. 1 : Development of glaucoma. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Open-Angle Glaucoma vs. Angle-Closure Glaucoma

These are the two main types of glaucoma. The “angle” here refers to the corner between the cornea and the iris where the trabecular meshwork is located.

Primary Open-Angle or Chronic Open-Angle Glaucoma is the most common form of glaucoma accounting for about 90% of cases. This is caused by partial blockage of the drainage canal. The angle is “open”, meaning the entrance to the drain is clear, but the flow of aqueous humor is somewhat slow. The pressure builds up gradually in the eye over a long period of time. There is no pain and visual loss appears gradually, starting from peripheral vision, and may go on unnoticed until the central vision is affected. Progression of glaucoma can be stopped with medical treatments, but part of vision that is already lost can not be restored. This is why it’s very important to detect signs of glaucoma early with regular eye exams.

Closed-angle or Acute angle-closure glaucoma (AACG) is less common. This type of glaucoma is caused by a sudden and complete blockage of aqueous humor drainage. The pressure within the eye rises rapidly and may lead to total vision loss quickly. This is a medical emergency and requires immediate attention. Symptoms to watch out for: sudden severe pain inside and around the eye, redness, blurry vision, seeing halos around a light, some people may also feel headache, nausea.

Certain anatomical features of the eye make it easier for AACG to happen. These include: narrow drainage angle, shallow anterior chamber, thin and droopy iris, lens sitting too much forward. These features are often inherited and so AACG incidents are likely to run in the family.

Fig. 2 : Open angle vs closed angle glaucoma. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Typically, this is what happens in AACG : the pupil is dilated (e.g. when looking in the dark) and the lens is stick to the back of the iris. This prevents the aqueous humor from flowing through the pupil into the anterior chamber (primary block). As the fluid accumulates in the posterior chamber it presses on the iris causing it to bulge outward and block the drainage angle (secondary block).

Other types of Glaucoma

Normal pressure glaucoma – Some people can get glaucoma (vision loss due to damaged optic nerve) without elevated intraocular pressure. This may be due to poor blood supply (e.g. damaged blood vessels in diseases such as diabetes) to the nerve fibers.

Secondary glaucoma – glaucoma develops as a result of trauma after eye injuries.

Congenital glaucoma – glaucoma that is present at birth.

Treatments

Progression of glaucoma can be halted or slowed down with medical treatments, but part of vision that is already lost can not be recovered. This is why it’s very important to detect signs of glaucoma early with regular eye exams.

– Eye drops that lower intraocular pressure and/or reduce fluid production.

– Laser treatments : Laser is used to burn part of the trabecular meshwork to improve fluid flow – laser trabeculoplasty. It can also be used to remove part of the ciliary body to reduce fluid secretion. For acute glaucoma, small holes can be made in the iris to relieve the primary block – laser iridotomy.

– Eye surgeries: a procedure called trabeculectomy is used to create a channel – an alternative route – for aqueous fluid drainage. For acute glaucoma a procedure called iridectomy may be performed to drill a hole in the iris. Canaloplasty is a newer, less invasive surgical procedure performed for treatment of open angle glaucoma. This procedure involves enlargement of the eye’s natural drainage canal.

In people with AACG, laser and surgical treatments may be performed for the other, still healthy eye as well to prevent future development of glaucoma.

Reverse Total Shoulder Replacement

The videos on this page can be downloaded upon purchase of a license on Alila medical Media website. Click here!

Reverse Total Shoulder Replacement or Delta Shoulder Replacement is a modification of total shoulder replacement procedure. The conventional procedure has a metal ball on the humerus (replacing the natural humeral head) and a plastic component on the glenoid. The reverse procedure has the reverse positions of the prostheses : the metal ball is now fixed on the glenoid socket and the plastic cup is fixed in place of the humeral head (Fig. 1). This configuration is indicated for people with rotator cuff arthropathy.

Fig. 1: Configuration of conventional versus reverse total shoulder replacement. Note the location of the metal head and plastic component in each case. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Why a conventional total shoulder will not work with rotator cuff arthropathy?

Rotator cuff arthropathy or cuff tear arthropathy (CTA) is shoulder arthritis in a setting of rotator cuff tears. Rotator cuff muscles hold the ball and the socket together and prevent the humeral head from moving out of the socket when the deltoid muscle raises the arm. In people with torn rotator cuff, the head of the humerus moves upwards out of the socket resulting in shoulder instability. Conventional total shoulder preserving the natural configuration of the shoulder joint will encounter the same problem (Fig. 2, left panel).

Fig. 2: Conventional versus reverse total shoulder replacement with torn rotator cuff. The upward force displaces the humeral head in conventional configuration but stabilizes the joint in reverse configuration. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Why a reverse total shoulder would work?

In reverse total shoulder procedure, the arthritic humeral head is replaced with a plastic cup and the metal ball is fixed onto the glenoid surface. With this configuration, the contraction of the deltoid will move the arm up and compress the socket to the ball at the same time (Fig. 2, right panel). The ball and the socket will fit more snugly together providing stability.

> See all Orthopedic topics

Femoral acetabular impingement (FAI)

What is femoral acetabular impingement (FAI)?

Femoral acetabular impingement (FAI) is a condition of hip joint where the bones are abnormally shaped, they pinch each other on the covering cartilages when the joint is in motion and cause damages.

The hip joint is a ball-and-socket joint (Fig. 1). The femoral head (the ball) fits into the acetabulum (the socket). The femoral head is covered with articular cartilage, the acetabulum has a ring of cartilage around its rim called the labrum. In FAI, there are abnormal bone growths (spurs) on the ball or the socket or both (Fig. 2). The ball can no longer move smoothly inside the socket. They rub onto each other and pinch on the covering cartilages causing damages.

Fig. 1 : Anatomy of the hip joint. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Types of FAI

Pincer – Bone spurs on the acetabulum, commonly on the upper edge (Fig. 2 ). This situation is also described as over-coverage of the socket over the ball.

Cam – Bones spurs on the femoral head and neck making the neck less prominent and the head not completely round.

Combined – both cam and pincer are present, this is a very common situation.

Fig. 2 : Types of FAI. Bones spurs are colored in red. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

What damages can it make?

Impingement results in cartilage breakdown on the femoral head and labral tears on the rim of the acetabulum. FAI is also the cause of premature hip osteoarthritis in young adults.

Causes and risk factors

The bone spurs are the result of abnormal bone growth during childhood development. The reasons why this happens are unclear.

FAI is more common in young athletes, dancers who practice a larger range of motions of the hip, and in active individuals.

Symptoms

Some of the symptoms may include:

– Pain at the groin area or inner hip is more common although the pain may be felt at the side of the hip.

– Pain after sitting for a long period of time.

– Stabbing pain when sitting down or standing up.

Treatment

Treatments range from lifestyle changes, physical therapies to surgeries.

Lifestyle changes usually involve being less active. Physical therapy helps to increase hip strength but stretching should be avoided.

Arthroscopic surgeries are commonly performed to remove damaged tissues, repair the labrum and stimulate cartilage growth by microfractures. Removal of abnormal bony structures are also recommended to prevent future damages to the joint.

> See all Orthopedic topics

Paranasal sinuses and sinus conditions

The videos on this page can be downloaded upon purchase of a license on Alila Medical Media website. Click here!

Paranasal sinuses, or simply “sinuses” in common language, are air cavities in the bones of the skull. There are four pairs of sinuses (see Fig. 1, 2 and upper panel of Fig. 3):

– the maxillary sinuses are under the eyes, in the maxillary bones.
– the frontal sinuses are above the eyes, in the frontal bone.
– the ethmoid sinuses are between the nose and the eyes, in the ethmoid bone.
– the sphenoid sinuses are behind the nasal cavity, in the sphenoid bones.

Fig.1: The four pairs of sinuses. Red = frontal, green = ethmoid, blue = sphenoid, beige = maxillary. The right panel show normal sinuses on half of the head and inflamed sinuses on the other half. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

The sinuses are lined with respiratory epithelium producing mucus. The mucus drains into nasal cavity through small openings (Fig. 2 left panel, Fig. 3 upper panel). Impaired sinus drainage has been associated with inflammation of sinuses (sinusitis, see below).
Biological function of the sinuses remains unclear.

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Fig. 2: Front view of the sinuses (left panel) showing connections to the nasal cavity. Right panel shows mid-sagittal section of the head. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Sinusitis or rhinosinusitis is inflammation of the paranasal sinuses (Fig. 1, right panel). This can be due to:
– allergy (allergic rhinitis): allergens such as pollen, pet dander,.. trigger overreaction of the mucosa of the nose and sinuses resulting in excess mucus, nasal congestion, sneezing and itching.
– infection: usually as a complication of an earlier viral infection of the nasal mucosa, pharynx or tonsils such as during a common cold. Impaired sinus drainage due to inflammation of nasal mucosa during a cold often leads to infection of the sinus itself. Cold-like symptoms plus headache and facial pain/pressure are common complaints.
– other conditions that cause blockage of sinus drainage: structural abnormality such as deviated nasal septum (Fig. 3); formation of nasal polyps (Fig. 4). When a sinus is blocked, fluid builds up making it a favorable environment for bacteria, viruses or fungi to grow and cause infection.

Fig. 3: Front view of the sinuses (upper panel) showing connections to the nasal cavity, also shown the nasal septum (light blue color). Lower panel shows deviated septum blocking drainage of the right maxillary sinus (your left). Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Fig. 4: Nasal polyps – overgrowths of nasal mucosa – block sinus drainage. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Treatment depends on the cause of sinusitis:
– For viral infection : symptom relief medications such as nasal spray for irrigation and decongestion; other conservative treatment for common cold such as rest and drinking plenty of fluid.
– For bacterial infection: antibiotics may be prescribed.
– For allergy: intranasal corticosteroids are commonly used.
– For recurrent (chronic) sinusitis due to structural abnormalities or nasal polyps, nasal surgery may be recommended.

See all Respiratory topics

Swallowing and Dysphagia (with Animation)

Swallowing

Below is a narrated animation about swallowing reflex, phases and overview of neural control. Click here to license this video on Alila Medical Media website.

Swallowing, or deglutition, is the process by which food passes from the mouth, through the pharynx and into the esophagus. As simple as it might seem to healthy people, swallowing is actually a very complex action that requires an extremely precise coordination with breathing since both of these processes share the same entrance: the pharynx. Failure to coordinate would result in choking or pulmonary aspiration. Swallowing involves over twenty muscles of the mouth, throat and esophagus that are controlled by several cortical areas and by the swallowing centers in the brainstem. The brain communicates with the muscles through several cranial nerves.

Swallowing consists of three phases

1. Oral or buccal phase: this is the voluntary part of swallowing, the food is moistened with saliva and chewed, food bolus is formed and the tongue pushes it to the back of the throat (pharynx). This process is under neural control of several areas of cerebral cortex including the motor cortex.
2. Pharyngeal phase starts with stimulation of tactile receptors in the oropharynx by the food bolus. The swallow reflex is initiated and is under involuntary neuromuscular control. The following actions are taken to ensure the passage of food or drink into the esophagus:
– The tongue blocks the oral cavity to prevent going back to the mouth.
– The soft palate blocks entry to the nasal cavity.
– The vocal folds close to protect the airway to the lungs.The larynx is pulled up with the epiglottis flipping over covering the entry to the trachea (the windpipe). This is the most important step since entry of food or drink into the lungs may potentially be life threatening.
– The upper esophageal sphincter (UES) opens to allow passage to the esophagus.
3. Esophageal phase: food bolus is propelled down the esophagus by peristalsis – a wave of muscular contraction that pushes the bolus ahead of it. The larynx moves down back to original position.

Click here to see an animation of the swallowing process on on Alila Medical Media website where the video is also available for licensing.

Fig. 1: Anatomy of swallowing. See text for details of phases. The blue arrows represent breathed air. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Dysphagia (swallowing disorders)

This video is available for licensing on Alila Medical Media website. Click HERE!

Dysphagia refers to a group of conditions characterized by difficulty swallowing. There are two main classes of problems that can lead to swallowing disorders:

1. Neuromuscular problems:

– Muscular disorders that affect skeletal muscles, such as muscular dystrophy, myasthenia gravis…

– Diseases of the nervous system that compromise the way the brain controls the swallowing reflex, such as stroke, Parkinson’s disease, multiple sclerosis…

– Weakened muscles and/or impaired coordination as a result of aging.

This class commonly affects the first two phases of swallowing.

2. Narrowing of the throat or esophagus due to throat cancer, esophageal cancer and formation of small sacs or rings in the walls of the esophagus. Gastroesophageal reflux disease – GERD – is also a common cause. In GERD, scars resulted from stomach acid injuries may obstruct the esophagus and cause difficulty swallowing.

This class mostly affects the third phase of swallowing.

Fig. 2: Schatzki ring makes the lumen of esophagus smaller. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

For people with dysphagia, eating becomes a challenge. The consequences may be serious. Someone who cannot swallow safely is at high risks of choking, pulmonary aspiration and may not be able to eat enough to stay healthy.

Treatment depends on the cause of the condition:

– Muscle strength and coordination exercises may be recommended for some.

– A change in the position of the head and neck when eating could be beneficial to others.

– Right choice of food and drink is important for most. Soft textured food and thickened drinks are recommended for safe swallowing.

– Surgery may be needed to remove narrowed parts of the esophagus.

– Finally, patients with severe dysphagia and recurrent aspiration may have to resort to tube feeding to get nutrition to the body.

See all ENT topics

See all Digestive topics

Vertical Sleeve Gastrectomy and Gastric Lap Band Surgeries

This is a continuation to the main article about bariatric surgery .

Below is a narrated animation of Gastric Sleeve and Gastric Lap Band procedures. Click here to license this video on Alila Medical Media website.

Vertical sleeve gastrectomy (VSG)

In this procedure a cut is made vertically and the larger part of the stomach (up to 85% of its volume) is removed from the body. The remaining is closed with staples to create a “new stomach” that is now having the shape of a tube (see Fig. 1). The procedure preserves both sphincters at the two ends of the stomach and therefore has minimum effect on the functioning of the digestive process.This reduces the risk of malabsorptive complications commonly associated with intestinal bypass. The procedure is irreversible.

Click here to see an animation of VSG procedure on Alila Medical Media website where the video is also available for licensing.

Fig. 1: Vertical sleeve gastrectomy procedure. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

VSG procedure is gaining more and more popularity thanks to its simplicity and good results on initial weight loss. However, due to the lack of long-term data, it is yet to be endorsed by bariatric surgery societies and is not covered by some insurance companies.

Adjustable gastric band (Lap band)

In this procedure an inflatable silicon band is placed around the top of the stomach to create a small stomach pouch (Fig. 2). During a meal, the pouch is filled up quickly with a small amount of food and releases it slowly into the lower part of the stomach due to the restriction by the band. As the pouch is full, it gives a feeling of satiety (fullness). Slow passage of the food makes the patient feel full for a longer period of time and thus reduces the amount of food intake. The band is connected to a port placed under skin of the abdomen. Through this port, a saline solution (salt water) is injected to adjust the diameter of the band and thus making the passage between the pouch and the lower part of the stomach smaller or larger accordingly to the needs of patient.

Click here to see an animation of gastric band procedure on Alila Medical Media website where the video is also available for licensing.

Fig. 2: Adjustable lap band procedure. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

As the procedure involves no cutting or stapling of the stomach, it is minimal invasive and reversible. The surgery can be performed laparoscopically (as opposed to open surgery) through small incisions with the aid of a camera. Recovery time is significantly shortened compared to gastric bypass procedures. Also, as there is no intestinal bypass, the risks of nutritional deficiencies, dumping syndrome and other complications associated with it are significantly reduced.
In terms of weight loss efficiency, however, patients who undergo gastric lap band surgery typically lose less weight than those who have had gastric bypass procedures.

> See Gastric bypass procedures

> See all Digestive topics

Common ankle injuries

Ankle anatomy

The ankle includes three bones : the tibia (shinbone), the fibula and the talus (Fig. 1). Articulations between these bones make up the ankle joint.

Fig.1: Anatomy of the ankle joint. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

The ankle is stabilized by the following ligaments (Fig. 2):
– tibiofibular ligaments connect the tibia to the fibula, one in front (anterior tibiofibular) and one in the back (posterior tibiofibular);
– lateral collateral ligaments connect the fibula to the talus (two of them: again one in front and one in the back) and to the calcaneus (the heel bone); and
– on the medial side, a multipart deltoid ligament connects the tibia to the talus and other bones of foot (the calcaneus and navicular).

Fig.2 : Ligaments of ankle. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Common ankle injuries include ankle sprains and ankle fractures.

Ankle sprain

Ankle sprain refers to injury to any of the ligaments of the ankle joint. This happens when the ankle is rolled or twisted beyond the normal range of motion and the ligaments are overstretched and torn. Commonly, the ankle moves suddenly outward while the foot turns inward resulting in overstretching of the ligaments on the outside of the foot (lateral ligaments). This type of sprain is called inversion (Fig. 3). On the other hand, when the ankle moves inwards and the foot turns outwards it’s the ligaments on the inside (medial) that are hurt. This type of sprain is called eversion and is much less common.

Fig.3 :Types of ankle sprain, illustrated for the right foot, anterior view. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Ankle sprains are common sport injuries. They can range from mild to severe depending on how bad is the damage and how many ligaments are involved (Fig. 4)

Fig.4 :Grades of ankle sprain. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

In most cases sprains can be treated with rest, ice pack, compression with a bandage and elevation (raising your foot up) to reduce swelling. Severe injuries may require surgery.

Ankle fracture

Broken bones of the ankle, a common sport injury. Commonly due to a direct blow to the ankle or a fall. Pott’s fracture (Fig. 5) represents a typical situation when the ankle receives a blow from the outside resulting in broken fibula at the point of impact. The talus moves outward shearing off a piece of the tibia. Medial ligaments are also injured in this case.

$Pott's fracture labeled.$
Fig. 5: Pott’s fracture. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Imaging techniques such as x-ray or CT-scan are used to determine the severity of fractures. If the broken bones are still in their normal position they will be immobilized (with a cast for example) to facilitate healing. Bones that are fallen out of place will require surgery. During surgery the bones are positioned back to their normal place, screws and metal plates are then used to keep the fragments together.

> See all Orthopedic topics

Common knee injuries and surgical repair, part 2

Knee sprains

Knee sprains refer to injuries in any of the ligaments of the knee. The most commonly injured are medial collateral ligament (MCL) running along the inner side of the knee, lateral collateral ligament (LCL) running along the outer side of the knee and anterior cruciate ligament (ACL) that connects the femur and tibia inside the joint (Fig. 1). For more about knee joint anatomy click here.

Fig. 1: Common types of knee sprain. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Commonly, injury happens after a direct blow to the knee. When the knee is hit from outside it moves inwards and the ligament on the inside (the MCL) is overstretched and injured. Inversely, when the blow comes from the inside of the knee it’s the outside ligament (the LCL) that is hurt. ACL injuries, on the other hand, are caused by twisting movement of the knee and are most common among athletes in sports that involve sudden rotation movement of lower leg.

Fig. 2: Completely torn ACL. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Mild sprains (stretched ligament but no tear or small tears) can be treated with rest, knee exercises and physical therapy. Complete tears require surgical repair or reconstruction.

ACL reconstruction surgery

Below is a narrated animation of ACL reconstruction surgery. Click here to license this video and/or other orthopedic videos on Alila Medical Media website.

This procedure is used to replace a severely damaged or completely torn anterior cruciate ligament (ACL) with a graft. The graft is a piece of healthy ligament taken from the same person or a donor. Graft from the same person is called autograft and usually works best. The procedure is detailed in Fig. 3. Autograft is commonly taken from the patellar ligament (one that connects the kneecap to the tibia), but hamstring tendon may also be used. See the figure legends for details of procedure, step 1 is done through open surgery, the rest are done through an arthroscope.

Fig. 3: Steps of arthroscopic knee surgery for reconstruction of anterior cruciate ligament injury: 1. Graft taken from kneecap and patellar ligament; 2. Torn ACL shown; 3. Damaged ACL removed and a channel is drilled through tibia and femur; 4. graft inserted and secured with screws; 5. graft in place. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

> See all Orthopedic topics

Common knee injuries and surgical repair, part 1

Knee anatomy

The knee has three bones : the femur (the thigh bone), the tibia (the shinbone) and the patella (the kneecap). The femur and the tibia form a hinge joint. The joint is enclosed by the joint capsule at the back and on the sides, and is covered by the patella and patellar ligament in front. The knee joint is stabilized mainly by the tendons of quadriceps femoris muscle in front and semimembranosus muscle (one of the hamstrings) on the back. Strengthening these two muscles therefore helps to reduce the risk of knee injuries.

Fig.1 : Midsagittal section of the knee joint. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Apart from the regular articular cartilage that cover the end surfaces of the three bones there are two additional pads of cartilage that are unique to the knee joint : medial meniscus and lateral meniscus (Fig. 2 and Fig. 3). The menisci act as shock absorbers to cushion the joint.

Two pairs of ligaments help to stabilize the knee : collateral ligaments run along two sides of the knee (Fig. 2), and cruciate ligaments which connect the femur and tibia in the center of the joint and cross each other in the from of an X (hence the names) : anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) (Fig. 2 and Fig. 3).

Fig. 2 : Front view of the right knee (the kneecap is removed in this picture to show structures behind). Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Fig. 3 : The right knee viewed from top (femur removed to show structures underneath). Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Meniscus tear and repair

Commonly referred to as torn cartilage, torn meniscus is a common sport injury. Mild injuries maybe treated with rest, ice, compression and elevation (the RICE approach). Larger tears may require surgery. The goal of surgery is to remove the damaged tissue which is the source of irritation, pain and possibly inflammation, and attempt to induce healing. Treatments vary depending on the location of the tear. If the tear is located on the outer border of the meniscus (the red zone, see Fig. 3) where there is a good blood supply, the damaged loose tissue will be removed and sutures will be used to tight the cartilage together to facilitate self healing. If the tear is located on the inner part (the white zone, see Fig. 3) where the blood supply is poor and hence healing is unlikely, the damaged part is simply removed (partial meniscectomy) (Fig. 4).

Minimal invasive arthroscopic surgery is commonly used for meniscus repair. In case of large tears, open surgery may be required.

Click here to see an animation of arthroscopic meniscus repair on Alila Medical Media website where the video is also available for licensing.

Fig. 4 : Treatment of meniscus tear depends on its location. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

> See all Orthopedic topics

Medical Information Illustrated

Medical and health topics fully illustrated with pictures and videos for easy understanding.

Tag Archives: drawing

Piriformis syndrome

Causes and Risk factors

Treatment

Glaucoma

How glaucoma develops

Open-Angle Glaucoma vs. Angle-Closure Glaucoma

Other types of Glaucoma

Treatments

Reverse Total Shoulder Replacement

Why a conventional total shoulder will not work with rotator cuff arthropathy?

Why a reverse total shoulder would work?

Femoral acetabular impingement (FAI)

What is femoral acetabular impingement (FAI)?

Types of FAI

What damages can it make?

Causes and risk factors

Symptoms

Treatment

Paranasal sinuses and sinus conditions

Swallowing and Dysphagia (with Animation)

Swallowing

Swallowing consists of three phases

Dysphagia (swallowing disorders)

Vertical Sleeve Gastrectomy and Gastric Lap Band Surgeries

Vertical sleeve gastrectomy (VSG)

Adjustable gastric band (Lap band)

Common ankle injuries

Ankle anatomy

Ankle sprain

Ankle fracture

Common knee injuries and surgical repair, part 2

Knee sprains

ACL reconstruction surgery

Common knee injuries and surgical repair, part 1

Knee anatomy

Meniscus tear and repair