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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.

Knee joint labeled drawing.

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).

Knee joint anatomy

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.

 

 

 

 

Knee meniscus labeled diagram.
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.

Meniscus tear and surgery treatment
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.

 

 

 

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Common shoulder injuries and surgical repair (part 2)

Rotator cuff injuries


Fig. 1 shows a group of four muscles that cover the shoulder joint. These muscles originate on the scapula and insert on the humerus: the supraspinatus,  infraspinatus, subscapularis and teres minor. The tendons of theses muscles form the rotator cuff (tendons connect muscles to bones). The most common injury to the rotator cuff is the impingement of one or more of these tendons. This may happen as a result of  a trauma or sport related injury but more commonly as a result of aging. The tendons may rub against the acromion (a bony extension of the scapula that hangs over the cuff) every time the person raises an arm and become irritated, inflamed and ultimately torn.

Rotator cuff muscles
Fig. 1: Rotator cuff muscles of the right shoulder. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 

 

 

Below is a narrated animation of arthroscopic rotator cuff repair.  Click here to license this video and/or other orthopedic videos on Alila Medical Media website.

Impingement usually develops over a period of time. Treatment includes rest, shoulder exercise, physical therapy and surgery. In most cases surgical treatment is done through an arthroscope but open surgery may be needed for larger tears. During surgery the damaged tissue is removed, source of irritation (commonly bone spurs on the acromion) is identified and removed. If there is no tear, the treatment may stop here and the surgical procedure is called shoulder debridement. In case of tear sutures will be used to tight the tendon back down to the bone (Fig.2).

Rotator cuff repair diagram.
Fig 2. Rotator cuff injury (1) and repair: small holes are drilled (2) into the bone of the humerus to hold small suture anchors with threads (3). The threads are attached to the tendon (4) and pulled tightly to hold the tendon to the bone (5). Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Separated shoulder

Separated shoulder is a condition affecting the “second” joint of the shoulder : the AC joint (acromioclavicular joint) between the acromion (an extension of the scapula)  and the clavicle. This condition is commonly due to a direct blow to the shoulder as in a fall or sport injury. Fig. 3 shows the ligaments involved in stabilization of AC joint, injury to any of these ligament results in separated shoulder. Injuries are graded according to the extend of tears and number of ligaments involved. Grade I injury (partial tear in one of the ligament) may be treated with simple rest and ice, small tears heal themselves over time. Grade III injury where the clavicle is completely detached from the scapula requires surgery where a screw will be inserted to fix the clavicle to the coracoid process of the scapula.

Separated shoulder, labeled diagram.
Fig.3 : Shoulder separation grading. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

Frozen shoulder (adhesive capsulitis)

The shoulder, like all synovial joint, has a capsule around it. The capsule encloses the two end surfaces of the bones involved in the joint and a joint cavity containing a lubricant called synovial fluid. In people with frozen shoulder condition this capsule is thicken and inflamed (Fig. 4) causing pain when they try to move an arm. The pain increases with time and the range of motion decreases, the shoulder becomes stiff or “frozen”.
Adhesive capsulitis of shoulder diagram.
Fig. 4: Frozen shoulder. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 

 

 

 

The causes of frozen shoulder are not fully established. People with diabetes and some other diseases show increased risk for frozen shoulder. It can also be resulted from a long-term immobilization of the shoulder (for example after a shoulder surgery). Treatments include pain management and physical therapy although in some cases surgery may be necessary. A procedure called arthroscopic capsular release  is usually performed to cut through the tight area of the capsule.

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Common shoulder injuries and surgical repair (part 1)

Anatomy


There are three bones in the shoulder: the humerus (the bone of the upper arm), the scapula (shoulder blade) and the clavicle (collarbone). Articulations between these bones make up the shoulder joints. The main joint, commonly referred to as “the shoulder joint”, is the joint between the head of the humerus and glenoid cavity of the scapula and is called the humeroscapular or glenohumeral joint. The second joint of the shoulder is formed by the articulation between the clavicle and the acromion (extension of the scapula that forms the top of the shoulder) and is called acromioclavicular joint or AC joint. The two joints are stabilized by associated muscles and ligaments.

Shoulder anatomy
Fig.1: Main components of the shoulder joint. Click on image to see a larger version on  Alila Medical Media website where the image is also available for licensing.

 

 

 

Shoulder dislocation

Shoulder dislocation occurs when the humeral head slips out of the pocket  made by glenoid cavity of the scapula (Fig. 2). This usually happens as a result of trauma (fall, sport injury,..). Dislocation can be anterior where the humerus slips to the front or posterior where it dislocates behind the normal position. Anterior dislocation is more common.

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

 

 

 

Below is a narrated animation about shoulder dislocation, bankart lesion and repair. Click here to license this video and/or other orthopaedic videos on Alila Medical Media website.

Bankart lesion and shoulder instability

The glenoid cavity has a ring of fibrocartilage tissue called the labrum around it. The labrum makes the cavity deeper and helps to keep the humeral head in place (Fig.3). During anterior shoulder dislocation, the head of the humerus may be pressed against and damages the anterior portion of the labrum. This type of labral tear is called bankart. Damaged labrum makes it easier for the humeral head to slip out of place again. This vicious cycle leads to repeated shoulder dislocation and severely damaged labrum. The condition is called shoulder instability as it feels like slipping out anytime. Treatment includes physical therapy and, in some cases, surgery for bankart repair (see below).

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

SLAP and bankart lesions
Fig. 3: Anatomy of the shoulder joint with the humerus slightly abducted to show the glenoid cavity and labrum. Types of labral lesions are shown on the right. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 

 

Bankart repair

During surgery the damaged cartilage is removed, area is cleaned, small holes are then drilled into the bone of glenoid fossa to hold small suture anchors with threads. The threads are attached to the labrum and pulled tightly to hold the labrum to the glenoid (Fig.4). Over time, the labrum will reattach to the glenoid naturally. Physical therapy will be needed to regain the shoulder range of motions and strength.

Shoulder stabilization surgery
Fig.4: Steps of bankart repair surgery. 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.

 

 

 

 

Bankart repair can be done with arthroscopic or open surgery. While arthroscopy is minimal invasive, open surgery maybe recommended for larger tears. In arthroscopic surgery only two or three small incisions are made, an arthroscope is inserted through one of the incision. Arthroscope is an instrument equipped with light and camera which transmits image of the joint to a computer screen. Other small tools are inserted  to carry out the repair (Fig.5).

Click here to see an animation of arthroscopic bankart repair.
Shoulder arthroscopy
Fig. 5 : Arthroscopic surgery for bankart repair. 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

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