A hip dislocation is a common occurrence among the elderly. It consists of the separation of the femoral joint and the socket of the pelvis. There are different types of hip dislocations, depending on where the joint surface of the femur lies with respect to the tibia. It is essential to obtain specialized help as soon as possible in order to avoid further damage.
“Hip joint has inherent stability due to bony as well as soft-tissue constraints including a deep socket of the ball-and-socket joint, thick muscular envelope of gluteal muscles, and strong supporting ligaments. Nevertheless, high-velocity trauma to the lower limbs is not infrequently associated with posterior hip dislocations, especially with dash-board injuries. Anterior type of hip dislocations are less common constituting around 15% of all hip dislocations. Such dislocations are often associated with injury to the nearby structures including fractures of the acetabulum and femoral head.”1
Types of Dislocation
We can distinguish between two types of hip dislocation:
- Anterior hip dislocation: the femoral head ends up shifting forward after dislocating from the acetabulum, that is, the concave articular portion of the pelvic surface. “Anterior hip dislocations are usually the result of forced abduction with external rotation of the thigh and often related to a motor vehicle accident or fall. There are three types of anterior hip dislocations: obturator, an inferior dislocation due to simultaneous abduction; hip flexion; and external rotation. Iliac and pubic dislocations are superior dislocations due to simultaneous abduction, hip extension, and external rotation.”2
“Anterior dislocation of the native hip joint is an uncommon presentation accounting for around 15% of all hip dislocations. It is usually the result of a high-energy impact in circumstances such as a motor vehicle accident or a fall from a significant height. A delay in relocation of more than 6 h has been associated with a high risk of avascular necrosis of the femoral head.”3
- Posterior hip dislocation: the femoral head dislocates behind the acetabulum. Posterior hip dislocation is the most common type by far, comprising of approximately 91% of all hip dislocations. “Posterior hip dislocation is more common than anterior or central luxation injury and represents 75 to 93% of the patients with dislocations of the respective joint. The mechanism of injury is a direct application of force on the flexed hip, which leads to internal rotation and adduction. The femoral head pops out of the articular cavity either superolaterally or inferolaterally. The typical causes of this pathology are motor vehicle accidents (dashboard injury); other causes are traumas from skiing or American football. Rarely, hip dislocation can also result from massive muscular convulsions due to electrical accidents or severe episodes of seizures. Consequences of hip dislocation typically include injuries of internal structures of the hip joint, proximal fractures of the femur as well as lesions to periarticular soft tissue.”4
“Common complications of posterior dislocations include avascular necrosis and traumatic arthritis. Avascular necrosis, caused by disruption to the circumflex femoral artery, is the dreaded complication of hip dislocation and occurs in 10% of cases. Other complications include injury to sciatic nerve, specifically the peroneal branch that is stretched over the displaced femoral head, potentially causing transient or permanent nerve injury. Prognosis is determined by several factors including time to reduction, overall trauma severity, age, comorbidities and frailty. Patients are often allowed to weight bear as tolerated afterwards, with close orthopedic and radiologic follow-up”5
A hip dislocation usually occurs due to severe trauma, for example, from traffic accidents or high-impact activities.
The symptoms produced by hip dislocation are:
- Pain around the hip.
- Functional impotence: inability to rotate the leg when performing an external or internal rotation, depending on whether the dislocation is anterior or posterior.
- Shortening of the limb and deformity in case of not receiving the necessary medical attention.
“Dislocations of the hip can be classified as congenital or acquired. Congenital dislocations result from the physiologic position of the fetus in utero pressed against the abdominal wall of the mother, with the additional component of the posterior force acting against a dysplastic hip joint in flexion. Both factors together result in a partial or complete dislocation in a neonate; however, this topic is beyond the scope of this paper. Acquired hip dislocations are either native dislocations or dislocations after total hip replacement. The majority of native hip dislocations result from motor vehicle collisions. In the typical scenario, the patient is sitting with the hip in flexion, and upon impact, the thigh hits the dashboard, sending a posteriorly directed force to the joint and causing a posterior dislocation. The most common acquired dislocation is hip dislocation that occurs within the first 3 months following total hip replacement. This scenario occurs when the patient reaches the extremes of the prosthetic range of motion and the femoral neck levers on the acetabular cup, allowing the femoral head to escape from the acetabulum. Other common conditions that can lead to postoperative dislocations include laxity or soft-tissue incompetence surrounding the hip joint (ie, revision), incorrect positioning of prosthetic components, and neuromuscular disorders (eg, Parkinson disease).”6
“Complex fracture-dislocations involve the acetabulum, femoral head, or femoral neck. The incidence of posttraumatic arthritis is much lower in simple dislocations than in fracture-dislocations. The most common mechanism of injury is a high-energy motor vehicle accident, which is usually associated with other systemic and musculoskeletal injuries. The hip should be reduced emergently in an atraumatic fashion. For acetabular fracture, intraoperative stress views may be necessary to evaluate for instability and to determine whether surgical fixation is required. The appearance of a concentric reduction on plain radiographs and CT does not rule out intra-articular hip pathology; such injury may contribute to long-term degenerative changes. Other complications of hip dislocation include osteoarthritis, osteonecrosis, and sciatic nerve injury. Indications for surgical management include nonconcentric reduction, associated proximal femur fracture (including hip, femoral neck, and femoral head), and associated acetabular fracture producing instability. Surgical management ranges from formal open arthrotomy to minimally invasive hip arthroscopy. Hip arthroscopy has become popular for treating intra-articular hip pathology, including loose bodies, chondral defects, and labral tears.”7
“Full trauma survey is essential because of the high-energy nature of these injuries. Many patients are obtunded or unconscious when they arrive in the emergency room as a result of associated injuries. Concomitant intraabdominal, chest, and other musculoskeletal injuries, such as acetabular, pelvic, or spine fractures, are common. Patients presenting with dislocations of the hip typically are unable to move the lower extremity and are in severe discomfort. The classic appearance of an individual with a posterior hip dislocation is a patient in severe pain, with the hip in a position of flexion, internal rotation, and adduction. Patients with an anterior dislocation hold the hip in marked external rotation, with mild flexion and abduction. The appearance and alignment of the extremity, however, can be dramatically altered by ipsilateral extremity injuries. A careful neurovascular examination is essential, because injury to the sciatic nerve or femoral neurovascular structures may occur at the time of dislocation. Sciatic nerve injury may occur with stretching of the nerve over the posteriorly dislocated femoral head. Posterior wall fragments from the acetabulum have the potential to injury the nerve. Usually, the peroneal portion of the nerve is affected, with little if any dysfunction of the tibial nerve. Rarely, injury to the femoral artery, vein, or nerve may occur as a result of an anterior dislocation. Ipsilateral knee, patella, and femur fractures are common. Pelvic fractures and spine injuries may also be seen.”8
The diagnosis of a hip dislocation does not usually require special tests. It can be determined by two factors. First, the patient presents an intense pain around the hip and second, the leg is immobilized with an external rotation or internal rotation if it’s an anterior dislocation or posterior dislocation, respectively. However, it is advisable to perform an imaging test of the area. This way, the existence of a bone fracture associated with the dislocation is discarded before trying to manipulate it.
- A radiological examination is sufficient to know the type of dislocation and to determine the appropriate treatment. If a radiography is not enough, it would be necessary to perform a CAT scan to check if there is displacement of the ligaments or fracture.
- A CAT scan (computerized axial tomography) is an imaging technique that uses X-rays to obtain image cuts or anatomical sections, in this case the hip. In the diagnosis of hip dislocation, the simple and three-dimensional CAT scan are used.
To prevent further serious injury, treatment for a hip dislocation should be started as soon as possible. This treatment consists of repositioning the femoral head back to its natural position.
In general, re-insertion of the femoral head to the acetabulum of the hip is carried out with local anesthesia, in order to maintain the muscles relaxed. General anesthesia will be used as a last resort only. Once the joint is re-established, an X-ray should be performed to rule out fractures associated with the dislocation. Next, the leg is immobilized. The usual practice is to leave the leg immobilized with repose without getting out of bed.
Once the resting time has passed, rehabilitation exercises are essential. This is to recover the strength of weakened muscles from prolonged by immobilization.
“All types of hip dislocation are time-sensitive emergencies that must receive prompt treatment. No more than 6 hours should elapse between presentation and reduction. Permanent complications and invasive procedures can become necessary if the hip is not reduced within the 6-hour window. Absent any contraindications such as fractures, IPD, or ipsilateral knee injury, a timely closed reduction can usually be performed under sufficient sedation in the emergency department.
Native dislocations are the most time-sensitive dislocations, as prolonged dislocation of the native hip can have detrimental effects on the femoral head (AVN) and chondral surface (chondrolysis). Because of the potential for fracture if the patient’s muscles remain active, […] On the other hand, administration of intravenous, general, or regional sedation has been proven to reduce complications and ease the modes of reduction in numerous studies.
In postoperative total hip replacement dislocations, if the prosthetic components are adequately positioned, most patients (67%) who undergo successful closed reduction will not experience another dislocation. Adequate sedation is required to properly relax the muscles and reduce the risk of injuring the patient or physician. Adequate sedation also reduces the risk of repeated attempts at closed reduction that can damage the prosthesis or injure the patient.”9
“Traumatic hip dislocation in children is relatively a rare injury accounting for about 5% of all hip dislocations1. Most of the hip dislocations seen in children are of the posterior type but the much rarer anterior and anterior-inferior (obturator) types have also been described. We report the case of an eight years old girl who presented to the accident and emergency department with this rare injury following a fall.”10
“The hip is a highly stable joint owing to its osseous, labral, ligamentous, and soft-tissue anatomy, usually requiring high-energy trauma to dislocate. Hip dislocations represent a spectrum of injuries, all of which are orthopedic emergencies with a relatively high rate of morbidity, predominantly due to posttraumatic osteoarthritis and avascular necrosis. Treatment by the orthopedic team is performed in two stages. At the initial stage, the goal is to perform rapid closed reduction of the hip. The second stage is focused on definitive management. Time from injury to reduction has been shown to be highly correlated with the risk for developing avascular necrosis. Evaluation of hip dislocation requires not only radiographic detection of subtle findings of dislocation and urgent communication to the treating physician, but also the inference of potential associated secondary osseous and soft-tissue injuries that could place the patient at risk for early osteoarthritis.”11
A physiotherapist will suggest stretching and muscle toning exercises. If immediate medical attention is not available at the time of hip dislocation, appropriate first aid may be put into practice. Some steps for this are:
- Immobilize the affected joint, absolute rest will be necessary to not aggravate the injury.
- Apply ice to the hip to produce an analgesic effect.
- Under no circumstances should you try to reposition the hip or administer any medication without consulting a doctor or professional.
Once these steps are followed it will be required to transfer the affected person to a medical center so the medical staff can carry out the necessary diagnosis and treatment.
(1) Selvanayagam, R., Tiwari, V., Das, S., & Trikha, V. (2018). Traumatic pubic-type anterior dislocation of the hip with an ipsilateral greater trochanter fracture: case report and review of literature. Cureus, 10(9). Available online at https://assets.cureus.com/uploads/case_report/pdf/14606/1542230402-20181114-6415-rxshjh.pdf
(2) Graber, M., & Johnson, D. E. (2018). Dislocation, Hip (Femur), Anterior. In StatPearls [Internet]. StatPearls Publishing. Available online at https://www.ncbi.nlm.nih.gov/books/NBK507814/
(3) Furness, N., Da Costa, T. M., & Bishay, M. (2013). Anterior hip dislocation in conjunction with a stroke: a diagnosis not to miss. BMJ case reports, 2013, bcr2012008356. Available online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3702794/
(4) Huber, F. A., Hirtler, L., & Kainberger, F. (2017). Muscle ruptures in posterior hip dislocation—a case report. BJR| case reports, 20170020. Available online at https://www.birpublications.org/doi/pdf/10.1259/bjrcr.20170020
(5) Xiao, J., Hamera, J. A., Hutchinson, C. H., & Berger, D. A. (2017). Bilateral posterior native hip dislocations after fall from standing. Clinical practice and cases in emergency medicine, 1(4), 329. Available online at https://www.researchgate.net/publication/321113399_Bilateral_Posterior_Native_Hip_Dislocations_after_Fall_from_Standing
(6) Dawson-Amoah, K., Raszewski, J., Duplantier, N., & Waddell, B. S. (2018). Dislocation of the hip: A review of types, causes, and treatment. Ochsner Journal, 18(3), 242-252. Available online at http://www.ochsnerjournal.org/content/ochjnl/18/3/242.full.pdf
(7) Foulk, D. M., & Mullis, B. H. (2010). Hip dislocation: evaluation and management. JAAOS-Journal of the American Academy of Orthopaedic Surgeons, 18(4), 199-209. Available online at https://www.researchgate.net/publication/42806704_Hip_Dislocation_Evaluation_and_Management
(8) Sanders, S., Tejwani, N., & Egol, K. A. (2010). Traumatic Hip Dislocation. Bulletin of the NYU Hospital for joint Diseases, 68(2), 91-6. Available online at http://presentationgrafix.com/_dev/cake/files/archive/pdfs/281.pdf
(9) Dawson-Amoah, K., Raszewski, J., Duplantier, N., & Waddell, B. S. (2018). Dislocation of the hip: A review of types, causes, and treatment. Ochsner Journal, 18(3), 242-252. Available online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6162140/
(10) Ahmad, S., Devkota, P., & Mamman, K. G. (2015). Traumatic Anterior Dislocation of Hip in a Child-Case Report. Malaysian orthopaedic journal, 9(1), 30. Available online at https://www.morthoj.org/2015/v9n1/traumatic-anterior-dislocation.pdf
(11) Mandell, J. C., Marshall, R. A., Weaver, M. J., Harris, M. B., Sodickson, A. D., & Khurana, B. (2017). Traumatic hip dislocation: what the orthopedic surgeon wants to know. Radiographics, 37(7), 2181-2201. Available online at https://pubs.rsna.org/doi/full/10.1148/rg.2017170012