Fig. 7.1
Evans classification of intertrochanteric hip fractures; division of stable fractures suitable for plates and screws and unstable fractures
Initial diagnostic studies should include an AP and cross-table lateral radiograph of the hip and an AP radiograph of the pelvis. If the diagnosis remains in question, a traction-internal rotation view of the hip (AP radiograph of the hip as it is held in 15° of internal rotation with axial traction) can be helpful by allowing visualization of the entire femoral neck in the absence of anteversion to decipher between questionable femoral neck and intertrochanteric fracture patterns. When no fracture is evident after standard radiographs, an MRI (within 24 h of injury) or bone scan (within 48–72 h of injury) can aid in diagnosis [8, 9]. Patterns that are non-displaced or border femoral neck fractures are usually appropriate to be treated by screws with side plates. Fractures with questionable instability can be confirmed with a lateral radiograph when evaluating posteromedial cortical integrity and sagittal displacement. The ability to determine which fractures are appropriate to be treated with screws and side plates will be defined throughout this chapter.
A variety of classifications of intertrochanteric hip fractures include the Evans classification , the AO classification , and the OTA classification [10, 11]. Traditionally, classification and treatment of intertrochanteric fractures have been based on determination of stability (Fig. 7.1). Stable patterns can be treated with either plates or intramedullary devices with cephalomedullary fixation. Instability patterns have been defined as including loss of ability to maintain a stable posteromedial buttress, reverse obliquity patterns, and presence of subtrochanteric extension [10, 11]. Fracture instability dictates the use of intramedullary nails (IMNs) with cephalomedullary fixation, which is discussed in the following chapter.
Stable patterns with intact lateral wall, including those with posteromedial comminution, are best treated with a sliding hip screw [12–14]. Fixation with a sliding hip screw in these stable patterns is associated with equivalent functional outcomes compared to cephalomedullary nails with decreased cost and lower perioperative complication rates [12–14]. In AO 31.A1 or 31.A2 fractures , patients treated with sliding hip screws with side plates have similar functional recovery scores compared to patients treated with cephalomedullary nails [15]. In a recent analysis of 4432 patients treated with sliding hip screws and cephalomedullary nails that looked at 30 day outcomes, operation time, rate of hospital readmission, and operating room time did not differ between groups although those treated with cephalomedullary nails had a 1 day shorter hospital length of stay, possibly negating the higher implant cost for the cephalomedullary nail [16].
More recently lateral wall competency has been considered as a mitigating factor to instability, as well. Lateral wall incompetency may be a result of comminution at the time of injury or iatrogenic comminution during side plate application with the use of the triple reamer [17]. At a point 3 cm distal to the vastus ridge, if the lateral wall thickness is less than 20.5 mm, there is an increased predilection for failures and reoperations when a sliding hip screw with side plate is used [17].
Plate Function, Technical Considerations, Limitations, and Options
Sliding hip screws with side plates work on the basic function of compression across a fracture in a dynamic mode. Historically, the sliding hip screw has been the implant of choice for the treatment of both stable and unstable intertrochanteric fractures. Sliding hip screw side plate angles are typically available in 5° increments from 130° to 150°. The 135° plate is most commonly utilized. This angle is easier to insert in the desired central position of the femoral head and neck than higher angle devices and creates less of a stress riser in the subtrochanteric region. In the past, biomechanical studies have shown no advantage of four screws over three to stabilize the side plate [18]. Recently, both biomechanical and prospective consecutive series supported the use of a two-hole side plate for stabilization of appropriate intertrochanteric fracture patterns [19–21].
Technique of Sliding Hip Screw with Slide Plate
Most frequently, the patient is placed on a fracture table with a well-padded perineal post. The unaffected leg is placed in a well-leg holder in flexion, abduction, and external rotation or padded and placed in hip extension and adduction while being secured to the leg-holding device.
Gentle traction is applied with the table and with subsequent rotation to match the distal to the proximal fragments. Various reduction maneuvers including traction in flexion or extension with external rotation to “unlock” the fragments followed by internal rotation will allow satisfactory reduction of the fracture. Confirmation of reduction must be done on both AP and lateral fluoroscopic views. The lateral will also show if there is excessive posterior sagging of the distal fragment. If present, this must be corrected and maintained throughout the procedure. This may be corrected externally with a support (crutch) or after dissection with the aid of reduction instruments.
An incision is made from the level of the vastus ridge, distally, for approximately 4 fingerbreadths. The iliotibial band is incised in line with the skin incision, and the vastus lateralis is elevated at the vastus ridge and then distally from posteriorly to anteriorly to expose the lateral femoral cortex. With the aid of the chosen angled guide (based on preoperative assessment of the femoral neck-shaft angle of the unaffected side), the guide wire is inserted through the lateral cortex, into the femoral head to a point within 1 cm of the center-center location on both the AP and lateral views. AP and lateral fluoroscopy is used to confirm position of the start point, the trajectory, and the end point. The tip-apex distance (the sum of the distance from the tip of the lag screw to the apex of the femoral head on the AP and lateral views, corrected for magnification) has been shown to be predictive of screw cutout after intertrochanteric fracture. If the tip-apex distance is ≤25 mm, the risk for screw cutout and resultant loss of fixation will be minimized [22].
Measurement of the proposed lag screw length is done, and then the triple reamer is inserted over the guide wire. Based on bone quality, tapping may be considered with the guide sleeve, followed by lag screw insertion. S crew insertion should ideally be within 1 cm of the subchondral bone. Subsequently, the side plate is applied over the lag screw to the lateral femoral cortex. Bicortical shaft screw fixation through the side plate is then performed, and if further acute compression is desired, the compression screw can be applied with concomitant release of traction and then subsequently removed (Fig. 7.2a–c).
Fig. 7.2
(a–c) Stable intertrochanteric hip fracture treated with a sliding hip screw demonstrating center-center position with a tip-apex distance of <25 mm
Alternatives to Standard Sliding Hip Screw with Side Plate
The variable angle hip screw (VHS ) (Zimmer Biomet, Warsaw, IN) is a sliding hip screw side plate device that allows angular adjustment of the side plate barrel to conform to different neck-shaft angles. This can allow for freehand guide wire insertion but should not be used to have excessive angular insertion of the guide wire for the main lag screw. A recent biomechanical study with the VHS has shown that mean compressive failure load was significantly higher in specimens dialed into a valgus angle of 150° compared to 135°. When load was applied to the two constructs, the 135° group exhibited more bending and shear, while the 150° group displayed more compression [23].
Unstable Fracture Patterns
With unstable intertrochanteric fracture patterns, failure occurs by excessive femoral shaft medialization and significant loss of offset. This can result in catastrophic mechanical failure, nonunion, and increased propensity for decreased ambulatory function even in the setting of union. Multiple studies have suggested that >15 mm of slide can increase the risk of these unwanted complications [24–28] including limb shortening, limp, and poorer outcome measures, especially in younger patients.
Excessive sliding occurs in reverse obliquity patterns, in subtrochanteric patterns, and with lateral wall incompetence because here, the sliding hip screw slides in line with the main fracture line, not perpendicular to it, therefore resulting in excessive displacement and shear stress at the fracture site (Fig. 7.3). The absence of the lateral wall results in a situation similar to that seen in the other unstable patterns discussed [29]. This is different from the expected normal sliding in an intertrochanteric hip fracture (type A1 or 2) (Fig. 7.4).
Fig. 7.3
(a, b) Reverse obliquity fractures are not suitable for sliding hip screw fixation as the fracture will slide along the screw and allow medialization of the shaft and significant shortening (From: Reverse obliquity fractures of the intertrochanteric region of the femur Haidukewych GJ, Andrew Israel T, Berry DJ. J Bone Joint Surg Am. 2001;83(5):643–50)
Fig. 7.4
(a, b) Expected fracture compression with a sliding hip screw may lead to shortening
Recent studies have shown that the excessive slide and concomitant lateral wall incompetence are directly related to patient age, iatrogenic comminution, and postoperative comminution seen. These factors are more predictive than gender, Singh index, implant position, or even quality of reduction [30]. Even in the setting of a tip-apex distance (TAD) of <25 mm, if lateral wall incompetency is present at the time of injury or created intraoperatively, this can lead to a seven times greater reoperation rate than in cases with an appropriate TAD and intact lateral wall [31].
Many additions/variations to the plate and screw implants have been developed to deal with instability. Some commonly used ones include the percutaneous compression plate (PCCP), trochanteric stabilization plate , and proximal femoral locking plates (PFLP).
The percutaneous compression plate (i.e., Gotfried plate) (Instrument Makkar, Okemos, MI) has two smaller diameter lag screw/barrel components which stabilize the femoral head and neck; this device was designed to be inserted through a minimally invasive surgical technique (Fig. 7.4 – PCCP) . Theoretically, these two lag screw components (9.3 mm and 7.0 mm diameters) provide greater rotational stability of the proximal fracture fragment. Other theoretical advantages provided by the use of two smaller diameter screws are preservation of the remaining lateral wall of the distal fragment. In unstable fracture patterns, it is the remaining lateral wall of the distal fragment which prevents excessive fracture collapse and subsequent fracture deformity. Placement of a large diameter single lag screw creates a larger defect in the lateral wall of the distal fragment that increases the risk of lateral wall fracture [32]. Early studies showed a decreased intraoperative blood loss and postoperative transfusion requirement than the standard sliding hip screw with side plate [32–34]. Also, smaller diameter drill device required for implant insertion has significantly decreased the potential of iatrogenically created lateral wall incompetence when compared to dynamic hip screws (DHS) even in three- and four-part intertrochanteric fractures [35].
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