Tag Archives: orthopedics

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.

Piriformis syndrome

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.

Lumbar spine disc herniation.
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.


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Temporomandibular joint (TMJ) disorders – disc displacement.

Temporomandibular joint (TMJ) anatomy and function

Below is a narrated animation about TMJ anatomy, disc displacement and natural adaptation. Click here to license this video and/or other related videos on Alila Medical Media website.


The temporomandibular joint (TMJ) is the joint between the lower jawbone – the mandible – and the temporal bone of the skull (Fig. 1). The TMJ is responsible for jaw movement and is the most used joint in the body.

The TMJ is essentially the articulation between the condyle of the mandible and the mandibular fossa – a socket in the temporal bone. The unique feature of the TMJ is the articular disc – a flexible and elastic cartilage that divides the joint into two parts: a upper joint and a lower joint.
Temporomandibular joint (TMJ).
Fig. 1 : Anatomy of the TMJ with jaw closed and open. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 

 

 

 

The disc serves as a cushion between the two bone surfaces. The disc lacks nerve endings and blood vessels in its center and therefore is insensitive to pain. Anteriorly it attaches to lateral pterygoid muscle – a muscle of mastication (chewing). Posteriorly it continues as retrodiscal tissue fully supplied with blood vessels and nerves. This is commonly the source of pain in disorders with anterior disc displacement (see below).

The jawbone (mandible) is the only bone that moves when the mouth opens. The first 20 mm (three quarters of an inch) opening involves only a rotational movement of the condyle within the socket. For the mouth to open wider, the condyle and the disc have to move out of the socket, forward and down the articular eminence, a convex bone surface located anteriorly to the socket (see Fig.1 and video below). This movement is called translation.

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

TMJ disorders

The most common disorder of the TMJ is disc displacement, and in most of the cases, the disc is dislocated anteriorly (Fig. 2, middle and lower panels). As the disc moves forwards, the retrodiscal tissue is pulled in between the two bones. This can be very painful as this tissue is fully vascular and innervated, unlike the disc. The movements made by chewing or even talking cause a chronic bruise to the tissue resulting in inflammation and pain.
Temporomandibular joint dysfunction, TMJ or TMD
Fig. 2 : Anterior disc displacement, “clicking” and “locking” symptoms, see text for details. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 

 

 

 

The forward dislocated disc is an obstacle for the condyle movement when the mouth is opening. In order to fully open the jaw, the condyle has to jump over the back end of the disc and onto its center. This produces a clicking or popping sound. Upon closing, the condyle slides back out of the disc hence another “click” or “pop”. This condition is called disc displacement with reduction.  In later stage of disc dislocation, the condyle stays behind the disc all the time, unable to get back onto the disc. The clicking sound disappeared but mouth opening is limited. This is usually the most symptomatic stage – the jaw is said to be “locked” as it is unable to open wide. At this stage the condition is called disc displacement without reduction. 

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

Fortunately, in most of the cases, the condition resolves by itself after some time. This is thanks to a process called natural adaptation of the retrodiscal tissue, which after a while becomes scar tissue and can functionally replace the disc. In fact, it becomes so similar to the disc that it is called a pseudodisc.

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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.
Conventional and reverse total shoulder replacement
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).

Shoulder replacement options for cuff tear.

 

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

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Shoulder arthritis

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

Shoulder arthritis refers to loss of cartilage on the surface of the ball (humeral head) and the socket (glenoid) of the shoulder glenohumeral joint. The two bones rub against each other and produce pain, stiffness and difficulty moving an arm.

Types and Causes of Shoulder arthritis

Osteoarthritis (OA) – also called degenerative joint disease (DJD), is the “wear and tear” condition of the joint commonly due to old age. OA is characterized by loss of cartilage, bone spurs (osteophytes) and no major inflammation (Fig. 1).
Shoulder arthritis
Fig. 1: Osteoarthritis of the main shoulder joint. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 

 

 

Rheumatoid arthritis (RA) – Inflammation of the synovium – the membrane that encloses the joint and contains lubricant fluid. Inflammation brings in the cells of the immune system whose inflammatory chemicals damage and destroy the joint. It’s not clear how RA starts but genetic predisposition together with infection of the joint are likely to be among the causes.

Rotator cuff arthropathy or cuff tear arthropathy (CTA) – Shoulder arthritis as a result and 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 person raises an arm. In people with torn rotator cuff, the head of the humerus moves upwards and rub onto the acromion. This causes damages to the covering cartilage and eventually arthritis. Combination of cuff tear and arthritis is a devastating condition that seriously compromises function of the shoulder.

Post-traumatic arthritis – arthritis that develops after physical injury to the joint.

Chondrolysis – sudden loss of cartilage that happens occasionally after a shoulder surgery, commonly seen in association with infusion of local anesthetics into the joint for pain management.

Treatments

Non-surgical treatments include shoulder exercises and anti-inflammatory medications.

Surgical treatments include a variety of procedures :

1. Total shoulder replacement surgery : the arthritic humeral head is replaced with a metal ball on a stem that fits inside the humerus, the socket is replaced with a plastic component made of high density polyethylene.
Total Shoulder Replacement

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

 

 

2. Ream and Run Arthroplasty – a modification of total shoulder procedure above. The metal ball replaces the humeral head but the socket is simply shaped, smoothed to fit the ball and left to heal. No plastic component used. With time, the body grows a cartilage layer on top of the socket. This procedure is recommended for younger and more active individuals.

3. Reverse total shoulder or Delta total shoulder replacement – This is indicated for people with rotator cuff  arthropathy (see types of shoulder arthritis above). This procedure reverses the positions of the prostheses : the metal ball is now fixed on the socket and the plastic component is fixed in place of the humeral head. This topic is covered in the next article about reverse total shoulder replacement.
                                                                                                          >  See all Orthopedic topics

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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.

Hip joint structure, labeled.

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.
Femoroacetabular impingement
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

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