Mechanism of injury and classification
Depending on their origin, dislocations are divided into congenital and acquired. Acquired dislocations, in turn, are subdivided into traumatic (resulting from a direct blow, fall, or sharp hyperextension) and pathological. Uncomplicated forms and complicated forms—when the injury is accompanied by fractures or damage to major vessels and nerves—are distinguished. Based on the presence of a wound over the joint, closed and open dislocations are differentiated.
In the pathogenesis, a key role is played by the rupture of the joint capsule, through which the bone end protrudes outward. Subsequently, the displacement is aggravated due to reflex muscle contraction. Most frequently (in 65% of cases), the shoulder joint is affected, while the elbow accounts for 25%. The high frequency of dislocations in spheroidal and hinge joints is explained by their anatomy: a spacious joint capsule, a weak ligamentous apparatus, and a small bone contact area.
Clinical presentation
Patients complain of sharp pain and the absolute impossibility of active movements, while any attempts at passive movements drastically intensify the pain syndrome. Objective examination reveals:
- Deformation of the joint region (e.g., an empty glenoid fossa).
- Forced position of the limb. In posterior hip dislocation, the leg is internally rotated, while in anterior dislocation, it is externally rotated; in posterior elbow dislocation, the olecranon protrudes.
- Change in dimensions — shortening (more often) or lengthening of the limb, as well as disruption of its axis.
Important rule: Before starting any manipulations, the physician is obliged to check the condition of the distal parts of the limb. Arterial pulsation, skin sensitivity, and finger mobility are assessed. This is necessary to rule out neurovascular complications.
Principles of reduction and conservative treatment
Treatment includes three mandatory stages: elimination of the dislocation, immobilization (from 5–7 days for the elbow to 3–4 weeks for the hip), and rehabilitation. Any closed reduction begins with complete anesthesia and myorelaxation.
Anesthesia methods:
- Local or combined (procaine intra-articularly, promedol subcutaneously) — for the shoulder, hand, foot.
- General anesthesia — mandatory for correcting hip and leg displacements.
- Use of muscle relaxants — in difficult cases to relieve muscle spasm.
Classic methods are used to reduce the shoulder: Kocher's method (sequential traction, external rotation, bringing the forearm forward, and placing the hand on the healthy shoulder), Janelidze's method (using the weight of the dangling arm to relax muscles within 15–20 minutes), and the methods of Motte and Hippocrates. The criterion of success is a characteristic click and restoration of movements. Radiological control is mandatory after the procedure.
Indications for surgical treatment
Surgical intervention is rarely resorted to. Open (surgical) reduction is required in the following situations:
- Open injuries — surgical debridement, correction of displacement, and suturing of the joint capsule are performed.
- Interposition of tissues — when soft tissues or bone fragments get trapped between the articular surfaces, making closed reduction impossible.
- Old (neglected) dislocations — due to scarring degeneration of the capsule and filling of the joint cavity with scar tissue, conservative reduction of the joint is impossible.
- Recurrent dislocations — develop due to rough reduction or improper treatment of the initial injury, leading to capsule incompetence. Plastic surgeries with tissue reinforcement are required to correct them.
Briefly: answers to topical questions
What absolute clinical signs of dislocation are revealed during objective examination?
Objective examination reveals a number of characteristic clinical signs of dislocation. These include:
- Deformation — a change in the shape of the joint region.
- Forced position — the limb assumes a specific posture typical of each type of dislocation.
- Change in length and axis — shortening (more rarely lengthening) and a change in the axis of the limb relative to proximal landmarks are usually determined.
- Absence of active movements — attempts at movement are impossible and cause sharp pain.
- Springy resistance sign — when attempting to passively move the limb out of the pathological position, elastic resistance occurs.
- Palpatory changes — the articular end is palpated in an atypical location or is not detected within the fossa.
What immobilization periods are indicated after closed reduction of a shoulder joint dislocation?
The duration of immobilization after closed reduction of a shoulder dislocation depends on the patient's age and the risk of recurrence. On average, fixation lasts from 2–3 weeks to 1 month.
- In young patients — immobilization lasts for at least 1 month with a rigid bandage (e.g., Desault bandage) to prevent the development of a recurrent dislocation.
- In elderly patients — the immobilization period is shortened to 3 weeks using a lightweight sling, as prolonged rigid fixation increases the risk of hypostatic complications.
Which nerves and vessels are most frequently damaged in anterior shoulder dislocation?
In anterior shoulder dislocation, the axillary nerve (n. axillaris) is most frequently injured, which can lead to paralysis of the deltoid muscle and decreased sensitivity along the outer surface of the shoulder. Damage to the median (n. medianus), ulnar (n. ulnaris), and radial (n. radialis) nerves is possible. Among blood vessels, damage or compression of the brachial artery may occur; this can manifest as weakened or absent pulse on the radial artery (a. radialis), as well as cyanosis or paleness of the fingers.
What forced position does the lower limb assume in posterior hip dislocation?
In posterior hip dislocation, the lower limb assumes a characteristic forced position, the basic sign of which is adduction and internal rotation of the hip. The degree of flexion depends on the specific type of posterior dislocation:
- Iliac (posterosuperior) dislocation — the hip is internally rotated, adducted, and slightly flexed.
- Sciatic (posteroinferior) dislocation — the hip is internally rotated, strongly adducted, and sharply flexed (including pronounced flexion in the knee joint).
What anatomical types of hip dislocations are distinguished depending on the direction of head displacement?
Depending on the direction of femoral head displacement in the sagittal plane, anterior and posterior dislocations are distinguished, which are further subdivided according to upward or downward displacement. There are 4 main anatomical types in total:
- Posterosuperior (iliac) — the head is displaced posteriorly and superiorly from the acetabulum (most common).
- Posteroinferior (sciatic) — the head is displaced posteriorly and inferiorly.
- Anterosuperior (pubic) — the head is displaced anteriorly and superiorly (beneath the inguinal ligament).
- Anteroinferior (obturator) — the head is displaced anteriorly and inferiorly (into the obturator foramen area).
Stages of Kocher's shoulder reduction: 1) Pull down and press the elbow → 2) Rotate externally → 3) Bring the elbow to the chest → 4) Place the hand on the healthy shoulder (internal rotation).
Class and exam questions
Why is it strictly forbidden to reduce a dislocation without anesthesia?
Pain causes reflex muscle retraction. Attempting to overcome it with brute force leads to additional ruptures of the joint capsule, scar formation, and a high risk of developing a recurrent dislocation.
What is the core principle of joint reduction using Janelidze's method?
The method is based on physiological muscle relaxation. The patient lies for 15–20 minutes with the injured limb hanging freely, after which the muscles fatigue, and reduction occurs with minimal effort.
What are the risks of unreduced and chronic dislocations?
In old injuries, the acetabulum fills with scar tissue, and the capsule undergoes degeneration. Closed reduction becomes impossible, and the patient requires complex surgery.
What else to study on this topic
- Detailed biomechanics of Kocher's method: errors and complications
- Differential diagnosis of anterior and posterior forearm dislocations
- Specifics of hip dislocations: iliac, sciatic, suprapubic, and obturator
- Principles of bandage application (Desault, sling) and plaster immobilization
- Joint capsule plication in the treatment of recurrent shoulder dislocation
Master the entire topic in the "General Surgery" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on the topic «Dislocations» and 3,335 more pages on the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 70 video lessons on the subject
Other topics in "CHAPTER 10. GENERAL ISSUES IN TRAUMATOLOGY"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.