Intracapsular Fractures of the Hip

The author reviews aspects of anatomy and physiology, especially vascularization and pathophysiology, as well as mechanisms of injury that inﬂ uence the treatment decision for intracapsular fractures of the hip. A number of other factors that may inﬂ uence surgeons’ choice between treatments are discussed, such as age, displacement, limited life expectancy, chronic disease


Treatment options
The author describes two general treatment options: internal fi xation and prosthetic replacement. Patient characteristics, fracture features, and bone quality must be considered when choosing between the two methods. The overall goal of treatment is to avoid avascular necrosis and other complications while achieving optimal reduction. After placement of a central and parallel guide wires, each pin/screw is drilled to a depth of 8-10 mm short of the tip of the pin/screw and then placed and tightened after the limb is released from any traction.

Objectives
To review the anatomy and physiology, epidemiological factors, mechanisms of injury, and treatment options at the time of publication for intracapsular fractures of the hip.

Study design
Comprehensive review article Background Risk factors ■ Increased age, dementia, a malignant tumor, cardioplumonary disease, race, and seasonal changes are found to be associated with an increased risk of hip fracture. ■ Long-term physical activity and in women, the use of supplemental vitamin D3 and calcium, reduce the risk of hip fracture.
Biomechanics of the fracture ■ More than 90% of femoral neck fractures are caused by a fall from standing position. ■ Femoral neck fractures resulting from high-energy trauma such as a vehicular accident or a fall from a substantial height are less common; the most likely injury is a dislocation with or without an associated fracture of the posterior acetabular wall or the femoral head. ■ Neuromuscular conditions are more frequently associated with an intertrochanteric fracture than with a femoral neck fracture. ■ Bone quality/osteoporosis play a critical role in the severity of fracture displacement and the achievement of a stable internal fi xation. Bipolar versus unipolar designs: ■ Bipolar designs have two sites of motion (the outer cup of the acetabulum and the inner bearing with the prosthetic head) and were designed to produce less acetabular erosion and to reduce the risk of dislocation of the prosthesis from the acetabulum. ■ Although dislocations of bipolar prostheses were reported to be less frequent than that of unipolar prostheses, superior results have not been proved conclusively. Prosthetic replacement compared with internal fi xation: ■ Controversy existed, due to the confl icting trial evidence available, about whether prosthetic replacement provides better outcomes than internal fi xation for patients over 65 years of age. ■ However, either operative treatment of displaced fractures substantially improved quality-adjusted life years and had substantial cost-benefi t implications.

Complications
Avascular necrosis: ■ Symptoms indicative of avascular necrosis are pain in the groin, buttock, or proximal part of the thigh, which may or may not reduce function. ■ Earlier and clearer recognition of the signs of avascular necrosis can be obtained using tomograms or computed tomography as compared to plain x-rays. ■ Risk of avascular necrosis corresponds to the degree of displacement of the femoral neck fracture seen on initial x-rays. ■ Patients with normal bone density have an increased risk of avascular necrosis. ■ Optimal reduction of the femoral neck fracture, which improves blood fl ow to the femoral head, has been shown to be associated with a lower rate of avascular necrosis. ■ Treatment of avascular necrosis is very diffi cult and includes options, such as core decompression, fl exion osteotomy, arthrodesis, and bipolar endoprosthetic replacement.
Failure of fi xation: ■ Pain in the groin or buttocks are symptoms of fi xation failure, usually occurring early in the postoperative period. Clinical suspicion can be confi rmed using plain x-rays or tomograms. ■ Lack of a stable reduction is the critical factor in failed fi xation and can be the result of inappropriate patient selection or technical problems, such as implants that do no provide adequate thread area for compression of the fracture. ■ Traumatic osteoarthritis can result from a failure of fi xation and the risk increases as the number of implants increases. ■ When fi xation fails, choice of treatment is related to patient age, functional demands, medical condition, and bone density: ■ In active individuals with good bone quality, reduction and internal fi xation should be repeated.

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In older patients with poor bone quality and lower functional demands, bipolar or total hip arthroplasty should be performed. ■ When failure is associated with a nonunion and varus deformity, a valgus osteotomy may be indicated.

Nonunion:
■ Pain in the groin or buttocks, especially on extension of the hip or with weight bearing, are symptoms of nonunion and occur earlier and are more severe than those of avascular necrosis. ■ Decision on how to treat nonunion is based on consideration of patient age, functional demands, medical condition, and bone density: ■ In young patients with good bone quality, treatment options include refi xation with a cancellous graft or a muscle-pedicle graft and valgus osteotomy.

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In older patients with bone loss, hip arthroplasty has shown to produce good or excellent results.