Table of Contents
Introduction:
The hip joint serves as an important connection between the head of the femur and the acetabulum (the socket of the hip joint) of the pelvis. It is a ball and socket joint which is a crucial joint that not only links the lower extremities to the axial skeleton but also enables movement along three significant axes. Moreover, the hip joint plays a vital role in supporting the body's weight. When the femur head is pushed out of the socket of the hip joint it is called dislocation of the hip joint.
What Is Anterior Hip Dislocation?
As discussed earlier the hip joint is a ball-socket type joint. In the anterior dislocation, the femur dislocates forward from its socket, causing a slight bend in the hip and rotation of the leg away from the body's center. It encompasses only 11 percent of cases of hip dislocation. This type of dislocation is usually caused by significant force during trauma. During such kind of events, the hip is forcefully moved outwards and rotated. Apart from trauma, poor fixation during total hip arthroplasty may also cause this. It should be kept in mind that, around 10 percent of people with total hip arthroscopy suffer from such kind of injury. The types of anterior hip dislocations are;
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Type 1 (Superior Dislocations): This is a very rare type of dislocation. Only 10 percent of cases of anterior dislocation cases are superior dislocation. Such injuries are also known as pubic dislocations or subspinous dislocations. These nomenclatures are given by the relative positioning of the femur after dislocation. This is usually caused by forced abduction, external rotation, and extension of the femur. Due to excessive force, the head of the femur the anterior inferior iliac spine is ruptured as it tears through the anterior capsule between the two ligaments: iliofemoral and pubofemoral, where the iliofemoral ligament is attached proximally. The type 1 fracture is further classified into three types. These types are the presence of no associated fractures, associated fracture of the femoral head or neck, and associated fracture of the acetabulum.
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Type 2 (Inferior Dislocations): This is mainly caused by forced abduction, external rotation, and flexion of the hip. During this injury, the femoral head protrudes through the anterior capsule below the pubofemoral ligament and settles in front of the obturator ring. The femoral head positioned over the obturator foramen, also known as obturator dislocation, and the abduction and external rotation of the femur are clear indicators of inferior dislocation, which can be easily identified on plain radiographs. This is again classified into types such as; the presence of no associated fractures, associated fracture of the femoral head or neck, and associated fracture of the acetabulum.
Why Anterior Hip Dislocation is Observed in the Elderly?
The prevalence of anterior hip dislocation is not significantly high in the elderly. However, the elderly have a higher risk factor of developing anterior hip dislocation than the young ones. The lack of neuromuscular coordination and neurological damage. These factors lead to frequent falls or lower limb injury. Also, loss of boner minerals due to physiological changes in the body and hormonal changes lead to mineral loss in the body. As a result, the bone becomes weaker.
What Is the Evaluation Process for Anterior Hip Dislocation in the Elderly?
Careful examination of the hip joint is necessary to determine anterior hip dislocation. Patients usually complain of severe pain and inability to move the leg of the affected site. Pain can be felt in the lower back region, abdomen, and in the knee area.
Several imaging modalities can be used for anterior hip dislocation. These are;
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Radiographic Evaluation: For the radiographic evaluation both anteroposterior (AP) and lateral positions are evaluated. In a normal AP view the pelvis will show femoral heads of equal size and symmetric joint spaces. An anterior dislocation will cause one femoral head to appear larger. Before attempting reduction, it is important to rule out a femoral neck fracture based on this image. The radiographic appearance of superior anterior hip dislocation can be similar to the posterior dislocation. This is because the femoral head appears superior and either medial (pubic) or lateral (iliac) to the acetabulum. The inferior anterior dislocation is more prominently visible AP view of the radiograph. Judet views (45-degree internal and external oblique views) are useful in evaluating the presence of bone fragments, and femoral head and neck fractures.
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Computed Tomography: Computed tomography is a useful method for three-dimensional reconstruction of the joint. This helps in diagnosing soft tissue injury, and the presence of intra-articular bone fragments. In the modern era, this helps in pre-operative planning. Even after the threat procedure, this is useful in joint space widening and soft tissue injury.
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MRI (Magnetic Resonance Imaging): This is mainly indicated for understanding soft tissue injury, nerve injury, and tear of the soft tissue structures such as muscles, ligaments, and cartilage.
How to Treat Anterior Hip Dislocations in the Elderly?
The management of the anterior hip reduction should be done as soon as possible. The first six hours are considered golden hours. Management during this period may minimize complications. In elderly people, open or surgical manipulation is often difficult due to medical complications. Complications such as low hemoglobin levels, severe cardiovascular disorders, and lung diseases are probable contraindications for surgical treatment. Different types of closed reduction methods are;
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Allis Maneuver: The Allis Maneuver techniques used for this purpose have some differences from the Allis maneuver used for posterior hip reductions. The patient is positioned supine while the practitioner stands over them. The pelvis is stabilized by applying pressure over the bilateral anterior superior iliac spines. The practitioner holds the affected leg just below the knee and, while slightly flexing the hip, applies constant traction to the hip joint along the long axis. The hip may be internally rotated and adducted. A gentle lateral force is also used in some cases. The reduction continues until an audible click is heard, indicating a successful reduction.
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Stimson Maneuver: This method is not commonly utilized because of the challenging patient positioning required. It is often recommended as a less invasive procedure. The patient is positioned prone with the affected leg hanging off the edge of the bed; the knee and hip are flexed as an assistant supports the lower back. The practitioner applies downward traction just below the knee, utilizing gravity to aid in the process. Internal and external rotation maneuvers are performed until a successful reduction is achieved.
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Captain Morgan Technique: The patient is placed in supine a position with both the knee and hip flexed. The operator adopts a stance with their foot on the patient's stretcher and their knee bent. This position is known as the "Captain Morgan" position. Positioned behind the patient's knee, the operator places one hand under the patient's knee and the other on their ankle. Using the first hand, the patient's femur is elevated. Subsequently, the operator exerts gentle downward pressure on the patient's ankle, effectively realigning the hip joint. To ensure stability, the pelvis can be secured using a strap or with the assistance of another individual.
Patients should be placed in a position where their legs are immobilized in a slight abduction, with a pillow or a device placed between their knees. It is necessary to apply ice packs and provide analgesia for pain relief. When a patient experiences an anterior hip dislocation after total hip arthroplasty, it is crucial to assess the stability of the hip. This evaluation should be performed under anesthesia, and the degree of all types of hip movement should be documented. The use of a hip abduction brace may be beneficial in these cases.
Conclusion:
Anterior hip dislocation is a relatively rare event. However, injuries due to trauma and poor bone density may increase the prevalence of such injuries in elderly people. The evaluation of such injury should be done as soon as possible. Radiographic methods and commuted tomography are the most used methods for this purpose. Closed reduction techniques are beneficial in elderly people due to challenging medical conditions.
