The central aims of proximal femoral fracture management are to provide either early stable internal fixation or replacement arthroplasty to relieve pain and allow early mobilization and functional rehabilitation. Acute total hip arthroplasty in elderly patients with displaced intracapsular fractures and acute hemiarthroplasty in older patients with unstable intertrochanteric fractures can produce good clinical outcomes and lower failure and reoperation rates than internal fixation. In cases in which internal fixation has failed, conversion to total hip arthroplasty is complex and has outcomes similar to revision total hip arthroplasty. Choosing the best surgical option in the treatment of the initial fracture is important to minimize the potential morbidity and mortality of a revision procedure in these patients. This chapter reviews the recent literature and the various techniques and pearls of acute arthroplasty for proximal femoral fractures and for conversion total hip arthroplasty after failed internal fixation of these fractures.
Internal fixation is associated with failure rates up to 43% and, consequently, high reoperation rates.
Acute total hip arthroplasty for displaced intracapsular fractures has similar perioperative complication rates and a better functional outcome. It has significantly lower complication rates than internal fixation and is no longer associated with unacceptably high dislocation rates.
In elderly patients with complex, unstable fracture patterns and poor bone stock, the risk of failure of internal fixation is high; these patients are probably best served by acute arthroplasty.
Conversion total hip arthroplasty has poorer outcomes and is associated with longer operative times, greater cost, and greater morbidity and mortality rates compared with primary internal fixation or acute total hip arthroplasty.
Careful preoperative planning, removal of hardware, appropriate implant selection, and secure fixation of the greater trochanter can help minimize the risk of surgical complications.
To restore length and maintain stability, choose a modular hip implant that has options for increased length or offset and allows alternate bearing surfaces that can tolerate a large head/neck ratio to optimize stability.
If proximal bone loss is present, use a cemented stem or bypass the deficient area by using an uncemented stem with diaphyseal fixation.
When performing arthroplasty for unstable intertrochanteric fractures, incorporate secure fixation of the greater trochanter, whether with wires, cable grips or plates or, as part of the femoral implant, as part of the procedure to minimize the risk of postoperative dislocation.
For screw removal, ensure the driver is well seated and try to advance the screws before turning counterclockwise in an effort to avoid stripping screw heads. Have a broken screw set available for these situations.
If using a cemented stem after screw removal, the screws can be cut and used to fill the lateral cortex and be removed after cementing. This avoids persistent cement-filled stress risers.
A trochanteric slide provides excellent exposure in conversion to total hip arthroplasty, but if used the greater trochanter must be securely fixed to maintain stability.
Comprehensive preoperative planning is crucial; when planning conversion to total hip arthroplasty, always consider infection. Perform preoperative inflammatory markers, send tissue samples, and be prepared for occult infection.
When converting failed internal fixation, dislocate the hip first before removing hardware to avoid iatrogenic fracture.
Minimize the risk of periprosthetic fracture by using a femoral stem of adequate length that bypasses cortical defects left by screws holes, extending at least two cortical diameters below the most distal hole.
A distortion of proximal femoral anatomy is common after unstable intertrochanteric fractures and should be assessed during preoperative planning. During conversion total hip arthroplasty, be aware that conventional reaming and broaching may be difficult and femoral canal preparation carries an increased risk of perforation and fracture.
Globally, more than 1.6 million fractures of the proximal femur occur annually, with approximately 250,000 each year in the United States alone. The incidence of fractures of the proximal femur in North America in men and women aged 35 years or older has been estimated at 0.16% and 0.28%, respectively. Incidence increases with advancing age and decreased bone mineral density, with the mean age for hip fracture being approximately 80 years. Greater annual numbers are expected with worldwide aging populations and growth in the health economic burden. Up to 80% of these global patients are women, with those older than 50 years having a 16% lifetime risk of sustaining a fracture of the proximal femur—a rate three times higher than that of men. Hip fractures also have more wide-ranging implications, being associated with a 25% decrease in life expectancy and a mortality rate of up to one third within 1 year of the fracture. Furthermore, patients spend an average of 17% of their remaining lives in a nursing facility, and most face a decline in ambulatory ability; less than half regain their prefracture mobility and almost one tenth become nonambulant.
The majority of proximal femoral fractures are intracapsular, with 60% occurring in the femoral neck. Trochanteric fractures comprise the remaining 40%, and almost one fifth of these are subtrochanteric. The central aim of surgery in these patients is to provide either early stable internal fixation or replacement arthroplasty to relieve pain, allow early mobilization and functional rehabilitation, and thus minimize potential associated morbidity and, importantly, avoid the potential morbidity and mortality of a second revision procedure.
ARTHROPLASTY IN THE MANAGEMENT OF ACUTE HIP FRACTURES
There is little controversy about the treatment of displaced intracapsular fractures in patients at the opposite ends of the age spectrum. Patients younger than 60 years are conventionally treated with reduction and internal fixation, whereas patients older than 80 years are conventionally treated with hemiarthroplasty. Choosing the best surgical option for physiologically fit and active patients between the ages of 60 and 80 years with displaced fractures of the femoral neck is not as clear cut. The reduction and internal fixation procedure is associated with high failure rates (up to 43%) and reoperation rates at least 2.5 times that of hemiarthroplasty. However, acetabular erosion limits the long-term success of hemiarthroplasty in this patient group. Acute total hip arthroplasty (THA) should offer a better alternative to this patient population, but the traditional arguments that acute THA has unacceptably high dislocation rates and is associated with increased operative time, increased cost, and potentially increased mortality rates have impeded its routine application. Despite these concerns, recent literature seems to be more supportive of THA in these cases.
In a retrospective review of 126 patients with fractures of the femoral neck treated with a primary cemented THA, Lee et al reported a 94% survival rate at 10 years, equivalent to that of primary THA. There was a 10% dislocation rate, but none progressed to revision THA. Several randomized, controlled trials have been performed comparing cemented THA with internal fixation and/or hemiarthroplasty with 2 to 4 years of follow-up. No differences were reported in mortality rates among the three treatment groups. Failure rates of 2.5% to 9% were reported for THA compared with 5% to 14.6% with hemiarthroplasty and 39% to 43% with internal fixation. All studies reported significantly better functional outcomes in THA compared with both hemiarthroplasty and internal fixation. Keating et al used a hip-specific and the EuroQol questionnaire, and Baker et al reported on walking tolerance and Oxford hip score data. Both reported significant improvements in these outcome measures. Blomfeldt et al used the Charnley hip score and demonstrated significantly better function in THA patients compared with internal fixation up to 12 months postoperatively. The dislocation rate in these studies ranged from 2% to 8%, comparable to the highest rates reported with revision THA. Only a minority progressed to revision surgery. Keating et al pointed out that even though the cost of the index procedure is higher in THA, the additional cost of subsequent admissions and revision surgery in failed internal fixation made THA (cemented THA in their study) a more cost-effective treatment option. Overall, a good case can be made for acute THA in “healthy” patients between 60 and 80 years of age because of its similar mortality rates, significantly lower failure and reoperation rates, and better functional outcomes compared with internal fixation.
The standard of care for extracapsular fractures in all patient groups is reduction and internal fixation. Extracapsular fractures, in contrast to femoral neck fractures, should have an excellent potential to heal once reduced and stabilized. Fixation of unstable fracture patterns, however, particularly simple and multifragmentary reverse obliquity fractures, is technically challenging and associated with high failure rates, up to 32%. Lower failure rates are associated with anatomic reduction (17%) compared with nonanatomic reduction (46%), ideal placement of the implant (26%) compared with nonideal placement (80%), and the use of fixed-angle devices (20%) compared with sliding hip screw implants (56%). The greater stability provided by newer generation cephalomedullary devices has improved results, but they still have failure rates ranging from 2.5% to 10%. Apart from technical and surgical considerations, osteoporosis has been shown to be an independent predictor of fixation failure. Low bone mineral density reflects poor bone stock in the femoral head and may be the ultimate limiting factor of internal fixation if cyclic loading will inevitably produce screw cut-out and fixation failure.
Acute hip arthroplasty in elderly patients with poor bone stock and unstable fracture patterns for which anatomic reduction and stable fixation do not appear readily obtainable may be a better treatment option to avoid a revision procedure. Hip arthroplasty may in fact be less technically demanding in such cases and has the advantage of achieving earlier patient mobilization by enabling full weight bearing. Published series of acute THA in this setting are small but report very high dislocation rates. Berend et al reported a 14% dislocation rate for their series of 29 patients with intertrochanteric fractures treated with acute THA and did not recommend it as a good surgical option for these fractures. Haentjens et al reported a 44.5% dislocation rate in nine THAs performed for unstable intertrochanteric or subtrochanteric fractures. The published experience with acute hemiarthroplasty is much better, with good clinical outcomes, low reoperation rates, and low dislocation rates reported. Kim et al reported a 3% dislocation rate in a series of 29 acute uncemented calcar replacement hemiarthroplasties for unstable intertrochanteric fractures. Grimsrud et al reported the same rate for their series of 39 acute cemented hemiarthroplasties for unstable intertrochanteric fractures. In both studies the dislocation was successfully treated without the need for revision surgery. Both groups emphasized the importance of secure fixation of the greater trochanter to the prosthesis to minimize abductor weakness and maintain stability.
Conversion to Total Hip Arthroplasty after Failed Internal Fixation
Failure of fixation is largely accounted for by nonunion, loss of fixation, hardware cut-out, or avascular necrosis. These patients as a rule have quite low Harris hip scores, reflecting the considerable pain and disability associated with failed internal fixation. Conversion to THA has poorer outcomes and is associated with longer operative times, greater cost, and greater morbidity and mortality rates compared with primary internal fixation or acute THA. Many factors mitigate against a good surgical outcome and make THA in the setting of failed internal fixation more comparable to revision rather than primary elective THA in terms of surgical complexity and patient outcomes.
As with other “revision” arthroplasty procedures, an accurate and thorough preoperative plan is critical. A full series of standardized radiographs of known magnification must be obtained to inform critical decisions regarding approach, hardware removal, and implant choice and fixation. The surgical approach, implant used, and secure fixation of the greater trochanteric fragment are important determinants of postoperative stability. Modular implant designs facilitate increased offset and increased head/neck ratio options. The newer alternate bearing surfaces, such as metal-on-metal couplings, allow larger cup and head size closer to the native hip joint, providing optimal implant design stability ( Fig. 19-1 ).