Hip Dislocation Following Total Hip Surgery

There are two types of hip joint dislocations: posterior and anterior. The position of the leg is important in determining the type of hip dislocation. When the hip is dislocated, the leg is usually shortened and it assumes a different position than the normal leg (the other leg). If the dislocation is posterior, the leg will be in adduction and internal rotation. If the dislocation is anterior, the leg will be in abduction and external rotation. Notice that the affected extremity is shortened and externally rotated. Leg shortening can also be seen in hip fractures and the leg will be shortened and externally rotated.

Dislocation of the hip following total hip surgery may require revision surgery, but it is rare. The majority of hip dislocations after total hip dislocations are posterior, and they are usually treated without surgery. Most occur within the first month of THA; 1-4% in primary, 16% in revision. There is more incidence of dislocation in revision hip replacement.

Causes & Risk Factors:

• Posterior Approach (try to repair the capsule adequately)
• Malposition of the component
  • Ideally, the normal cup component will be in 20° of anteversion and 40° of abduction
  • When the hip dislocates posterior, always check for retroversion of the cup.

• Prior hip fracture surgery, especially in the elderly
• Weakness of the abductor muscle—must achieve soft tissue tension and function
• Alcohol abuse
• Improper neck length—looseness of the hip

The patient should be careful to avoid all activities that cause dislocation after total hip surgery. The patient should use a pillow between the legs while sleeping on their back and they should be careful to not cross their legs in their sleep. Patients cannot sleep on their sides as well. The patient should not bend the body at the waist farther than 90°. When sitting, the patient must avoid chairs that make it difficult to stand up, and sit at more than a 90° angle. The patient must not sit with their legs crossed in the chair. The patient must be made aware that if the leg is changed from its usual position, or becomes shortened, then the hip is probably dislocated and their doctor should be consulted.

X-rays of the dislocated total hip should include AP and lateral views. Look for eccentric wear and look for the position of the prosthesis. CT scans may be needed before or after reduction of the dislocation to check the version of the components. Treatment is variable and depends on the situation. The treatment should be tailored for each case. The majority of these cases with early dislocations can be treated successfully with closed reduction and immobilization.

The treatment should start with closed reduction of the total hip and immobilization. Hip stability is checked after reduction of the dislocation. Immobilization can be done by a brace or a hip spica. Trochanteric osteotomy and advancement of the trochanter and tensioning the abductor muscle. Screws or wires can be used. The prosthesis must be in good alignment for this procedure to work. Constrained acetabular components are used when the abductor muscle is deficient and the component position is good. Revision total hip is done in recurrent dislocation with malposition of the component or polyethylene wear.

Stem Cells and Orthopaedics

Stem cells may help tissues that are injured or damaged to renew and regenerate themselves. Depending on the treatment and medium, stem cells have the ability to become different types of cells such as bone, cartilage, and blood vessels. There are several conditions in which stem cells are used as treatment, including: avascular necrosis, arthritis, and nonunion.

When Avascular Necrosis of the femoral head occurs due to the diminished blood supply, there is a death of a segment of bone, which is considered necrotic. The surgeon can inject stem cells into this area to revive this area by drilling into the bone. When using stem cells to treat AVN, the surgeon will need to create a channel for new blood vessels to form into the area that lacks blood supply. After the channel is created, the stem cells are injected into the necrotic femoral head.

Stem cell treatments for joint pain and arthritis is not proven to be effective. However, there is some use in knee arthritis for cartilage regeneration.

 

The best use of stem cells in Orthopaedics is its treatment for nonunion fractures. A nonunion fracture is classified as a fracture that does not heal after a reasonable period of time or a fixation failure. Nonunion may also be due to motion of the bony ends and incomplete healing of the fracture; fractures of this nature will need a lot of assistance. Two elements are needed for treatment of nonunions: vascularity—which improve the local conditions to facilitate healing; and stability—in the form of fixation such as a rod or plate.

The most common causes of nonunion are smoking (5 times more common), diabetes, obesity, osteoporosis, unstable fixation, infection (most common), open fractures, and the severe displacement of the fracture.

 Options available for treatment:

1. Bone Morphogenetic Protein—very expensive
2. Bone Graft—donor site morbidity
3. Stem Cells

Stem cells must be extracted from the bone marrow and are aspirated and harvested from the anterior iliac crest. This procedure is performed with an outlet view under fluoroscopy. Once extracted, the bone marrow is prepared to be centrifuged. After centrifuging the bone marrow, a good sample is extracted for injection.

The surgeon will mark and localize the area for injection and the trocar is placed. The sample will then be injected into the fracture area—occasionally, two areas of nonunion are treated. Adult mesenchymal stem cells are special cells that can copy themselves, divide, and multiply. They can differentiate into bone cells that heal the nonunion and lay down new bone. This process can be monitored by alkaline phosphatase activity or by the genes of the stem cells. The whole cellular mechanism can help increase the vascularity of the nonunion.

It is important to note that adult mesenchymal stem cells are not embryonic stem cells. There is a large amount of information in regards to stem cells that is lacking or misleading. Cells should probably be combined with some type of matrix. Additionally, surgeons need a better delivery system and localization during the injection of the stem cells due to the fact that the dye kills the cells. It is beneficial to allow the cells to expand and grow in the culture prior to injection. Moreover, the effect of certain medications such as aspirin, Plavix, and Coumadin, should be studied further.

 

 

Hip Dislocations

Hip dislocations can occur posteriorly or anteriorly; however, any type of hip dislocation is considered an emergency.

Posterior hip dislocations are more common and the lower limb will be flexed, adducted, and internally rotated. Posterior dislocations are frequently caused by dashboard injuries. The impact with the car dashboard drives the femoral head backwards out of the acetabulum. The physician will want to observe sciatic nerve function and examine the knee to rule out a PCL injury as well. Weakness of the ankle and toe dorsiflexion due to an injury to the peroneal division of the sciatic nerve may result in foot drop. The patient will also be unable to dorsiflex the ankle.

Anterior hip dislocation is rare. Superior Anterior hip dislocation results from the lower limb being extended, abducted, and externally rotated. Inferior Anterior Hip Dislocations (obturator type) results from the lower limb being flexed, abducted, and externally rotated.

An emergency reduction of dislocations is needed in less than 8 hours of the injury. An urgent reduction is mandatory to avoid avascular necrosis and interruption of the blood supply, which leads to a collapse of the femoral head. AVN is the death of a segment of bone.

Treatment

A CT scan should be obtained after reduction to evaluate the presence of fragments in the joint and access stability of the joint. Hip joint dislocations may be associated with acetabular or femoral head fractures (Pipkin). An urgent closed reduction of the hip dislocation followed by stabilization of either of the fractures if needed according to the protocols.  

Orthopaedic Emergencies Part II

Knee Dislocations

Dislocations at the knee occur as a result of a violent trauma. For example, a Posterior Dislocation—the dashboard injury, is the most common mechanism of injury which includes exaggerated hyperextension of the knee and dashboard (posteriorly directed force with the knee flexed at 90 degrees). Posterior dislocation is associated with a high incidence of popliteal artery injury. With an established popliteal artery injury and resultant ischemia, blood flow must be restored within 6 hours. Posterior tibialis and dorsalis pedis pulses should be carefully evaluated in any patient with a knee dislocation. Look for any evidence of ischemia, diminished blood flow, or compartment syndrome. Incidence of nerve injury range from 14 percent to 35 percent. Be cautious of spontaneously reduced knee dislocations and its associated pathology.

Urgent reduction of the knee dislocation is mandatory. Once the reduction is complete, it is important to reevaluate circulation. If the circulation is normal, serial follow-up up to 48 hours with clinical examination and non-invasive studies (ABI). If the circulation is abnormal, an arteriography should be performed. If no pulses are palpable, immediate exploration will need to be initiated. The arterial injury is treated, circulation restored, and prophylactic fasciotomy may be necessary.

Posterior Sternoclavicular Joint Dislocation

A Posterior Sternoclavicular Joint Dislocation typically results from either a direct force applied to the front of the medial clavicle or an indirect force applied to the posterolateral aspect of the shoulder. Posterior dislocation of the sternoclavicular joint could be missed. It is imperative to look for compression of the trachea, esophagus, or great vessels of the neck. A posterior dislocation is difficult to diagnose by x-ray so a CT scan is the preferred method for diagnosing the dislocation and any associated complications. An urgent reduction is mandatory in order to assure that a closed reduction is successful and stable. Open reduction may be performed if a closed reduction is unsuccessful. If an open reduction is decided, during the operation, a cardiac surgeon will be waiting standby.

Scapulothoracic Dissociation

Scapulothoracic Dissociation is a rare entity that consists of disruption of the scapula-thoracic articulation. It is a closed avulsion of the scapula with associated clavicular fracture or disruption of its articulations and severe soft tissue injury. This injury has been described as a closed, traumatic fore-quarter amputation. It is a traumatic lateral displacement of the scapula with intact skin. It is associated with upper extremity fractures such as fractures of the scapula, clavicle, and humerus. Most often, there are varying degrees of injury to the brachial plexus and the subclavian artery, resulting in a flail and pulseless upper extremity. An arteriogram should be performed to diagnose a vascular injury. A chest x-ray shows significant lateral displacement of the scapula; however, the injury can be missed!

First method of treatment consists of advanced trauma life support (airway breathing, circulation), followed by an arteriogram for evaluation of the vascular injury and repair of the arterial injury, if possible.

Fat Embolism

Fat embolism syndrome is a clinical diagnosis with non-specific or insensitive diagnostic tests. This occurs in trauma patients with multiple long bone fractures or pelvic fractures. Suspect fat embolism syndrome with the appropriate signs and underlying risk factors. The clinical signs usually develop within 24-72 hours of the injury. A fat embolism will develop earlier than a pulmonary embolism. Early stabilization of the fractures decreases the rate of incidence of this complication.

Major signs of a fat embolism include: confusion, agitation, petechial rash—axillae, conjunctivae, palate, and shortness of breath. Minor signs are listed as: tachycardia, fever, anemia, thrombocytopenia, and fat in the urine. For a diagnosis of a fat embolism, there must be one major sign and four minor signs, as mentioned above. Treatment of the fat embolism consists of diagnostic tests—however these are non-specific and insensitive, supportive treatment—such as intubation and oxygenation, and prevention (stabilization of long bone fractures).

Femoral Fracture in the Multiply Injured Patient

In a multiply injured patient, early skeletal stabilization of a femoral fracture within 24 hours results in decreased incidence of pulmonary complications and fat embolisms. The effect of reamed intramedullary nailing for femoral fractures on the incidence of pulmonary complications in a multiply injured patient or patients with concomitant chest injury is controversial. Multiple studies have shown that reamed intramedullary nailing for the acute stabilization of femoral fractures in the multiply injured patient with a thoracic injury did not increase the occurrence of pulmonary complications. External fixation is indicated for early stabilization of femoral fractures in severely injured patients as a form of damage control in orthopedics and as a temporary bridge to femoral nailing. External fixation is also indicated in the presence of an associated vascular injury requiring stabilization before repair and in the presence of severe soft tissue injuries with extensive contamination.

Hip fractures in an elderly patient

Nonoperative treatment in elderly patients with hip fractures results a high complication rate including pneumonia, thromboembolism, urinary tract infection, and decubitus ulcers, resulting in a high mortality rate.

The mortality rate is 25% in the first year following the fracture. Early surgery within 48 hours of an injury has been shown to be associated with a decreased one-year mortality rate. 

Complications in Hip Fractures

Dislocations occur more in total hip arthroplasty than in hemiarthroplasty. Too much retroversion causes posterior dislocation. Total hip arthroplasty is done is physiologically active elderly patients with a displaced femoral neck fracture. Although it may increase the risk of dislocation, there is a lower revision rate and a superior long term future outcome.

Failure of fixation

Quality and maintenance of reduction of the fracture is important. Closed reduction can be attempted, however the reduction must be anatomic. If it is not anatomic reduction, then open reduction should be done. Open reduction can be done through an anterior approach or a Watson-Jones approach. When the fixation fails, you can attempt to repeat ORIF or you may do prosthetic replacement. It is important to note that in elderly patients, treatment of displaced femoral neck fractures with screws may have failures and revision rates of up to 40%.

Fracture Distal to the Fixation

This is probably due to screw placement at or below the lesser trochanter and poor bone quality, especially if you start anteriorly and not laterally. It is also possible that this may be due to the poor angle of the screw fixation and multiple attempts at drilling or guide pins. Treatment typically consists of a refixation of the femoral neck and the subtrochanteric fracture.

Nonunion of the fracture

Femoral neck fractures are considered to be intracapsular fractures which are at a high risk of developing a nonunion. The femoral neck fracture is surrounded by synovial fluid and there is no extraosseous blood supply, no periosteum, or callus formation. The fracture healing occurs by intraosseous bone healing alone. It can present itself as groin or buttock pain, pain with hip extension, or with weight bearing. It can occur in about 5% of nondisplaced fractures and about 25% of displaced fractures. If it occurs in an elderly patient, an arthroplasty must be done. If it occurs in a young patient, a valgus intertrochanteric osteotomy. A vascularized fibular graft may benefit the patient as well. Nonunion fractures occur more in the vertically oriented fracture pattern with loss of reduction and varus collapse. In younger patients, we may possibly reorient the fracture line to be more horizontal by doing the osteotomy. Usually, the nonunion is apparent by about twelve month; however, there may be trouble in seeing the nonunion due to the fact that there is no periosteum and no callus in the femoral neck.

Medical Complications

There is an increased risk of DVT of up to 80%. Some form of prophylaxis is indicated, both mechanical and pharmacological for the patient. It is imperative to consult the medical team for co-management. The aim of treatment is early immobilization of the patient with pulmonary toilet. There is a high mortality rate in the elderly—approximately 30% in one year. A surgical delay of more than 72 hours will increase the risk of one year mortality. After completion of the treatment, treating the osteoporosis is needed to decrease the incidence of other fragile fractures.

Osteonecrosis (AVN)

The patient will have groin, buttock, or proximal thigh pain. It occurs in 10% of nondisplaced fractures and in 30% of displaced fractures. AVN could occur due to interruption of terminal branch of the medial femoral circumflex artery by the fracture. The medial femoral circumflex artery is the predominant blood supply to the femoral head. Usually, AVN is diagnosed by an MRI or it can be obviously on the x-ray. Not all cases of AVN develop evidence of radiographic collapse. AVN can be clinically significant when it is followed by late segmental collapse.

Late segmental collapse can be seen as early as 6-9 months following the fracture, but it is usually recognized by the second year. Segmental collapse can be excluded if it does not occur by the third year. AVN may occur due to an increase in the initial displacement, increase in the time to reduction, or nonanatomic reduction. Treatment for AVN in younger patients with less than 50% femoral head involvement may qualify for a valgus intertrochanteric osteotomy. A free vascularized fibular graft or a total hip replacement may be considered if the involvement of the femoral head is more than 50%. In an elderly patient, a total hip arthroplasty will probably be necessary.

Penetration of the screws into the hip joint.

Another possible complication is the penetration of the screws into the hip joint. The screws should be placed within 5mm of the articular cartilage. You can use multiple fluoroscopy images to confirm that there is no penetration. The screws must be parallel so that it can allow the fracture to be compressed. Make sure the threads of the screws cross the fracture site, otherwise the threads will distract the fracture. You may use long threads or short threads based on the situation.

Shortening

Femoral neck shortening after fracture fixation with multiple cancellous screws can be a problem. The healed femoral neck fracture with shortening is usually associated with a poor functional outcome.