Clinical Cases - Joints of the Upper & Lower Limbs
One evening while playing in the yard, a father picked up his four-year-old daughter by her hand and started swinging her around in a circle. At first the girl giggled, but all of a sudden, she cried out in pain. When her father put her down, he noticed that she was holding her elbow. Her arm was partially flexed and pronated, and she was unable to supinate her hand without considerable pain, so her parents took her to the emergency room. When the physician palpated her elbow, she found that the joint was tender, especially on the lateral side, but all of the bony landmarks were in their normal locations, leading the physician to suspect that the head of the radius had slipped out of the annular ligament. Radiographs proved inconclusive. Fairly certain of the diagnosis, however, the physician attempted to reposition the head of the radius by supinating the forearm fully and then flexing the elbow. She felt a small pop on the lateral side of the cubital fossa as the head of the radius slipped back into position and within a few moments the girl's elbow was as good as new.
Questions to consider:
- What is the annular ligament and where is it located?The annular ligament is a circular ligament which forms a collar around the head of the radius, holding it firmly in place without directly attaching to the radius. This allows relatively free rotary movement of the radius at its proximal articulation with the capitulum of the humerus. The annular ligament is attached to the anterior and posterior margins of the radial notch on the ulna.
- What are the bony landmarks that are readily palpable at the elbow?The olecranon process of the ulna, lateral and medial epicondyles of the humerus, and the head of the radius are generally readily palpable at the elbow. The three-dimensional relationships of these landmarks are important in diagnosing injuries to the elbow joint.
- This sort of elbow dislocation (pulled elbow, or subluxation of the head of the radius) is common in pre-school aged children, whose radial heads are somewhat small relative to the size of the annular ligament. What other types of elbow dislocations are common and how do they present?Other common injuries to the elbow include:
- Posterior dislocation of the elbow: These are common in children and generally result from falling on an outstretched hand with the elbow flexed. These are easily recognized by unusual protrusion of the olecranon posteriorly along with displacement of the distal end of the humerus anteriorly, disrupting normal articulation with the forearm at the radial head and trochlear notch.
- Avulsion of the medial epicondyle: Also common in children, this injury results from a fall that causes severe abduction of an extended elbow. The ulnar collateral ligament, which is stronger than the fusion of the diaphysis and epiphysis of the humerus at the medial epicondyle, pulls the medial epicondyle away from the humerus. This epiphyseal plate does not usually fuse until around 20 years of age.
- Separation of the proximal radial epiphysis: This injury again happens only in children and is a displacement of the radial head following a fall that places a compression and abduction force on the elbow. This epiphysis usually fuses around 14-17 years of age. In adults, fractures of the elbow tend to occur more frequently than dislocations.
- Why might the radiographs have been unhelpful in this situation?The radiographs probably were not helpful because this injury is not likely to tear the joint capsule and as a result, the head of the radius may not be obviously displaced on films. Furthermore, obtaining them was likely difficult in itself because of the age of the patient and the severity of pain caused by manipulation of the elbow.
- What nervous structure is particularly vulnerable in elbow injuries and where is it located?The ulnar nerve, which passes behind the medial epicondyle and crosses the medial ligament of the elbow, is particularly vulnerable in elbow injuries. The ulnar nerve is often crushed in elbow injuries, which may lead to sensory loss and muscle weakness or paralysis in regions of ulnar distribution. Symptoms may appear immediately or after some delay. The effects of ulnar nerve damage are noticed particularly in the hand.
The goalkeeper in a soccer match fell on his outstretched left arm. He felt an immediate pain in the shoulder region and was unable to move his arm. At the hospital the arm was abducted and the deltoid muscle looked flat or hollow. The injured arm looked "too long", and there was intense pain on attempting to move the arm. A plain radiograph of the region showed that the humeral head was lying below the glenoid labrum and that there was no fracture of the humerus. The diagnosis was an anterior dislocation of the shoulder, and the orthopedic surgeon recommended Kocher's maneuver for management.
Questions to consider:
- Why did the deltoid appear flat and hollow?
Because of the downward displacement of the humeral head.
- What neurovascular structures are liable to be injured in such a condition? How do you examine the patient to rule that out?
The axillary nerve and the posterior humeral circumflex artery. Axillary nerve injury may be assessed clinically by examining skin sensation over the deltoid region, which is supplied by the upper lateral brachial cutaneous branch (C5) of the axillary nerve. Examining the deltoid will be difficult in dislocated shoulders.
- What is the anatomical principle in reducing a dislocated shoulder?
The elbow must be flexed under traction, humerus laterally rotated, adducted and then rotated medially. An X-ray is taken to ensure proper reduction, and axillary nerve function is assessed by asking the patient to abduct the shoulder.
The star running back of a college football team was cutting outside to evade a potential tackler and take advantage of a block when he was hit on the posterolateral side of his right knee by an opponent. At the time of impact, the running back's right foot was firmly planted as he was changing directions. The leg was severely abducted by the blow, and the knee buckled as the running back collapsed to the turf in severe pain. A stretcher was required to remove him from the field. He was then transported to the university hospital where the knee was thoroughly examined. Severe pain was localized to the medial side of the right knee, and a drawer test was positive. The running back's knee was determined to require surgery, and he was unable to return to the playing field until the following season.
Questions to consider:
- Based on the information given, what ligaments were probably injured?The medial collateral ligament and the anterior cruciate ligament were involved in this case. The localized pain medially suggests a medial collateral ligament injury and the positive drawer test indicates a ruptured anterior cruciate ligament.
- What other structures may also be injured?The medial meniscus is probably also damaged because it is attached to the medial collateral ligament. Undue stress from a blow to the lateral side of the knee usually results in tearing of both the medial collateral ligament and the medial meniscus.
- What is the drawer test?The drawer test involves firmly grasping the leg with both hands just below the knee with the thumbs on the tibial tuberosity. With the knee flexed, the examiner pushes and pulls the leg in a line parallel to the long axis of the femur. Excessive mobility anteriorly indicates a ruptured anterior cruciate ligament, while excessive posterior movement suggests a ruptured posterior cruciate ligament.
- What was the goal of surgical intervention?Surgery for an athlete (as in this case) would be aimed at repair of the medial collateral and anterior cruciate ligaments and the medial meniscus; however, in severe injuries, the medial meniscus may need to be removed entirely. Depending on the severity of the damage to the ligaments, transplants of ligaments or tendons from other locations (i.e. the patellar tendon) may be required to help stabilize the knee. In non-athletes, patients with anterior cruciate ligament damage often do not have the ligament repaired because it is not absolutely essential to knee stability and because repairs are not always successful. These patients are taught to compensate for the injury using their quadriceps muscles.
- Why does a blow on the lateral side of the knee usually produce a more serious injury than a blow to the medial side?Because the medial collateral ligament and the medial meniscus are attached, these structures are frequently injured together as a result of a blow to the lateral side of the knee. The same is not true for blows to the medial side of the knee. In this case, only the lateral collateral ligament is usually injured. The lateral collateral ligament and the lateral meniscus are not attached to each other, but are separated by the tendon of the popliteus muscle.
A paratrooper was taken to the hospital complaining of bad pain in the right foot caused by improper and forceful landing on her heel. Upon arrival at the hospital her injured foot was swollen, deformed and held rigid. AP, lateral and oblique x-rays were done, and an undisplaced fracture of the talar neck was shown. The orthopedic surgeon ordered a split plaster of Paris that should be reapplied when swelling settles.
Questions to consider:
- How would the talus get fractured as a result of a fall on the heel?
The upward thrust of the calcaneus against the talus and tibia may fracture the talus.
- What other bones may fracture from such trauma?
Calcaneus and lower end of the tibia.
- In this case, the surgeon should do a special examination of the vessels in the vicinity of the fractured talus. Which vessel is of importance in this respect?
The dorsalis pedis pulse is important to be checked in such cases.
- What complication may arise from such a fracture?
Avascular necrosis and non-union.
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