Malalignment of the lateral femoral wall
Eleven patients showed this kind of pattern [Figure 3]. These fractures showed good contact of the medial cortices and anterior cortices [Figure 3A and 3B]. However, the AP fluoroscopic image showed a displaced lateral femoral wall. For displaced lateral femoral walls with a relatively large tilting angle, we tried to reduce and provisionally fix them with K-wires [Figure 3C]. Then, the fracture was fixed using an intra-medullary fixation device [Figure 3D].
Separation of the lateral femoral wall on the sagittal plane
Nine patients showed this kind of pattern [Figure 4]. A coronal fracture line of the lateral femoral wall was always present. These fractures showed good contact of the medial cortices and anterior cortices [Figure 4A and 4B]. However, the lateral fluoroscopic image showed a separation of the lateral femoral wall on the sagittal plane. For fractures with evident displacement of the lateral femoral wall, we tried to use a clamp to reduce the fragments and cannulated screws to fix them [Figure 4C–4F]. Finally, the fracture was fixed with a locking compression plate [Figure 4G and 4H].
Lateral displacement and posterior sagging of the femoral shaft relative to the head-neck fragment
Nine patients showed this kind of pattern [Figure 5]. Intra-operative images showed a laterally displaced femoral shaft relative to the head-neck fragment on the AP view [Figure 5A] and posterior sagging of the femoral shaft on the lateral view [Figure 5B]. Attempts at closed reduction were unsuccessful. A periosteum elevator was used to push the head-neck fragment posteriorly [Figure 5C and 5D], and a mallet was used to lift up the femoral shaft. Keeping the bone hook and mallet in situ, the fracture was fixed using an intra-medullary device.
Medially displaced femoral shaft relative to the head-neck fragment
Six patients showed this kind of pattern [Figure 6]. Intra-operative images showed a medially displaced femoral shaft relative to the head-neck fragment on the AP view [Figure 6A], while good alignment was observed on the lateral view [Figure 6B]. A bone hook was used to pull the femoral shaft laterally [Figure 6C]. Both the anterior and medial cortices were reduced [Figure 6C and 6D]. Keeping the bone hook in situ, the fracture was fixed using an intra-medullary device.
Reduction quality and follow-up
After applying the above reduction techniques, the reduction quality of fractures was substantially improved. According to the grade of reduction quality, 53 cases had good reduction quality (70%), 15 cases had acceptable reduction quality (20%), and eight cases had poor reduction quality (11%) [Table 2]. The mean follow-up time was 24.3 months (range, 3–75 months). Overall, implant failure occurred in ten (13%) of 76 patients. Of the 53 cases with good reduction quality, implant failure occurred in five cases (9%). Two cases of screw breakage, one case of helical blade cut-out, one case of helical blade perforation, and one case of main nail breakage occurred. Of the 15 cases with acceptable reduction, quality implant failure occurred in two cases (2/15). One case of helical blade cut-out and one case of screw breakage occurred. Of the eight cases with poor reduction quality, implant failure occurred in three cases (3/8). One case of helical blade cut-out, one case of screw breakage, and one case of main nail breakage occurred.
The initial univariate analysis revealed that four factors were associated with fracture irreducibility, including a medially displaced femoral shaft relative to the head-neck fragment on the AP view (OR, 7.62; 95% CI, 3.16–18.39; P < 0.001), a displaced lesser trochanter (OR, 3.29; 95% CI, 1.45–7.51; P = 0.005), a displaced lateral femoral wall (OR, 3.86; 95% CI, 1.51–9.85; P = 0.005), and a BMI <18.5 kg/m2 (OR, 0.20; 95% CI, 0.06–0.67; P = 0.010) [Table 3].
After controlling for confounding variables using multivariable analysis, three factors were identified as predictors of irreducibility: a medially displaced femoral shaft relative to the head-neck fragment on the AP view (OR, 8.00; 95% CI, 3.04–21.04; P < 0.001), a displaced lesser trochanter (OR, 3.61; 95% CI, 1.35–9.61; P = 0.010), and a displaced lateral femoral wall [Table 4] (OR, 2.92; 95% CI, 1.02–8.34; P = 0.046).
Trochanteric fractures usually require surgical treatment. As most patients are elderly and have many comorbidities, minimizing surgical trauma, reducing intra-operative blood loss, and shortening the duration of the operation are important. Despite improved techniques and various implant modifications, implant failure remains a challenging problem for unstable fractures.[11–13] Many factors are associated with implant failure, including osteoporosis, age at the time of surgery, fracture classification, and reduction quality. However, reduction quality is a controllable factor for doctors.[14,15] The quality of fracture reduction determines the fracture prognosis to a large extent. A satisfactory fracture reduction ensures early rehabilitation exercise; therefore, reducing the complications caused by a long-term bedridden status. Intertrochanteric fractures are usually initially treated with closed reduction. However, for some intertrochanteric fractures, achieving satisfactory reduction by closed manipulation is difficult, and various types of open reduction are, therefore, required. These fractures are defined as irreducible fractures.[2–4] However, to the authors’ knowledge, few studies have been conducted on predictors of and reduction techniques for irreducible reverse intertrochanteric fractures. We therefore retrospectively analyzed 113 cases of reverse intertrochanteric fractures to summarize the radiographic features and displacement patterns of irreducible reverse intertrochanteric fractures and corresponding reduction techniques and to explore predictors of irreducibility.
No precise definition of an irreducible reverse intertrochanteric fracture currently exists. We used the reduction quality of fractures after closed manipulation to identify irreducible fractures. However, no useful reference for evaluating intra-operative reduction on fluoroscopy during surgery is available. Baumgaertner and Solberg assessed reduction quality with respect to the amount of displacement and neck-shaft alignment on immediate post-operative AP and lateral radiographs, which was categorized as good, acceptable or poor. A “good” reduction displays normal or slightly valgus neck-shaft alignment on the AP radiograph, under 20° of angulation on the lateral view and a displacement of less than 4 mm on either view. “Acceptable” reductions meet the requirements regarding alignment or displacement, but not both, whereas “poor” reductions do not meet any of the requirements. However, the extent of displacement is a parameter that cannot be measured intra-operatively with a fluoroscope. Kim et al described displacement of the proximal medial cortex with respect to the distal fragment on the AP view and the anterior cortex on the lateral view in terms of cortical thickness. A displacement of <1 cortical thickness implies contact between the proximal and distal fragments. We believe that the criteria proposed by Kim are more practical for clinical application to describe the extent of displacement. However, the criteria do not include an evaluation of alignment, which is also important for a good reduction. Consequently, this study adopted modified criteria to evaluate reduction quality.
The incidence of irreducible intertrochanteric fractures has been reported to vary from 3% to 17%.[2,4,16] However, these incidence rates are all related to AO/OTA 31-A1-type and A2-type fractures. To the authors’ knowledge, no reports on the incidence of irreducible reverse intertrochanteric fractures have been published. In this study, irreducible fractures accounted for 67% of reverse intertrochanteric fractures. In other words, more than half of reverse intertrochanteric fractures are not amenable to closed manipulation. In cases of such fractures, many surgeons may repeatedly adjust the traction table to attempt closed reduction; however, the reduction quality will not be improved. Sometimes, a patient may be draped despite poor reduction quality, leading to an increased implant failure rate.
Reverse intertrochanteric fractures differ from AO31-A1 and A2 pertrochanteric fractures in that the major fracture line runs from distal-lateral to proximal-medial. The reverse fracture line and the function of the adductor muscles may lead to femoral shaft medicalization, which sometimes requires limited reduction maneuvers. Torn dorsal soft tissues and gravity may cause sagging of the shaft on the traction table, resulting in the need for dorsal support. According to intra-operative fluoroscopy images after closed manipulation, these fractures can be grouped into six patterns.
The most common pattern was observed in 30 patients. All of these patients showed a transverse or short oblique main fracture line with an intact greater trochanter. The lesser trochanter was attached to the femoral shaft fragment. The femoral shaft may displace medially under the function of the iliopsoas and adductor muscles. However, the head-neck fragment may displace laterally and upward under the function of the gluteus medius and gluteus minimus. At the same time, the femoral shaft sagged posteriorly due to gravity. Consequently, increasing the traction force would have only caused aggressive displacement, thus, limited open reduction was then considered. A bone hook can help reduce the medially displaced femoral shaft [Figure 1].
The second pattern was observed in 11 patients. The possible mechanism may be that the femoral shaft sagged posteriorly due to gravity, however, the head-neck fragment was in a balanced state under the function of muscle groups. Chun et al reported a kind of percutaneous reduction technique to reduce unstable sagittal intertrochanteric fractures, where a mallet was used to elevate the thigh. We have also tried this method, but achieving a good reduction was sometimes difficult because we could not precisely control the femoral shaft. The technique that we used in this study could not only reduce the fracture exactly but also protect surgeons from radiation.
The third pattern was observed in 11 patients. We found that these patients commonly have a long oblique main fracture line. The lateral femoral wall showed abduction and external rotation under the function of the gluteus medius, gluteus minimus, piriformis, and obturator internus. For a displaced lateral femoral wall with a relatively large tilting angle, we tried to reduce and provisionally fix it with K-wires. Then, the fracture was fixed using an intra-medullary fixation device. Intertrochanteric fractures with a fracture of the lateral femoral wall have high rates of implant failure.[17,18] However, to the authors’ knowledge, no useful reference for the evaluation of reduction focusing on the lateral femoral wall is available. We suppose that malalignment of the lateral femoral wall represents a pattern of unsatisfactory reduction. However, further research is needed to confirm this hypothesis.
The fourth pattern was observed in nine patients. All of these patients had a coronal fracture line of the lateral femoral wall. For fractures with evident displacement of the lateral femoral wall, we tried to use a clamp to reduce the fragments and cannulated screws to fix them [Figure 4]. However, screws may impede medullary nail insertion. Therefore, we used a locking compression plate instead. In this study, three patients underwent lateral femoral wall fixation with screws. The lateral femoral wall in the remaining six patients was not fixed. None of the patients experienced implant failure.
The fifth pattern was observed in nine patients. All of these patients showed a transverse or short oblique main fracture line with the lesser trochanter attached to the head-neck fragment. The head-neck fragment may displace medially along with external rotation under the function of the iliopsoas muscle, iliofemoral ligament, and pubofemoral ligament. In addition, the gluteus medius and gluteus minimus could not exert the function of abduction because of the comminuted greater trochanter. Then, the femoral shaft displaced laterally relative to the head-neck fragment. At the same time, the femoral shaft sagged posteriorly due to gravity. A periosteum elevator and a mallet may help to reduce the fracture [Figure 5].
The last pattern was observed in six patients, where a medially displaced femoral shaft relative to the head-neck fragment was shown on the AP view, while good alignment was shown on the lateral view. All of these patients showed a transverse or short oblique main fracture line with an intact greater trochanter. The mechanism of this pattern has been explained in the discussion on the first pattern. We used a bone hook to pull the femoral shaft laterally [Figure 6].
Although various reduction techniques were adopted in this study, eight cases (11%) still had poor reduction quality. Among them, seven cases showed the first displacement pattern, and one case showed the fifth displacement pattern. All of these cases had re-displacement after final fixation.
Surgeons must be able to recognize irreducible fractures pre-operatively and may need to prepare for a limited open reduction. Based on other studies[15,19,20] and our experience, we considered age, the mechanism of injury, BMI, AO/OTA classification, the statuses of the lesser trochanter and the lateral femoral wall, the type of fracture line, and femoral shaft displacement relative to the head-neck fragment on the AP view to be factors associated with irreducibility. Therefore, a univariate regression analysis of the above factors was conducted. We found that four factors were related to irreducibility [Table 3]. After controlling for confounding variables via multivariable analysis, three factors were identified as predictors of irreducibility: a medially displaced femoral shaft relative to the head-neck fragment on the AP view, a displaced lesser trochanter, and a displaced lateral femoral wall [Table 4]. As mentioned above, a medially displaced femoral shaft relative to the head-neck fragment may be due to the function of the adductor muscles; in this case, achieving a satisfactory reduction through closed manipulation is difficult. A bone hook may be useful to pull the femoral shaft laterally [Figure 1C]. The characteristic of reverse intertrochanteric fractures is that the greater trochanter is attached to the head-neck fragment. If the lesser trochanter is displaced, then both the gluteus minimus and iliopsoas fail to control the femoral shaft. Consequently, the femoral shaft will sag posteriorly due to gravity. For these fractures, closed reduction may be difficult, and re-displacement is not uncommon. A displaced lateral femoral wall indicates that free bone fragments are present at the junction of the greater trochanter and the lateral femoral wall. A comminuted lateral femoral wall complicates reduction of the fracture.
This study had some limitations. First, the study design was retrospective, causing the analyses to be inherently more susceptible to missing data, biases, and confounding factors compared to a prospective study. Second, this study focused on patterns of displacement, reduction techniques, and predictors of irreducible reverse intertrochanteric fractures and did not examine the clinical and functional outcomes of all patients. We believe that this research must be continued by developing clinical trials and well-structured studies to provide strong scientific evidence regarding this topic.
In summary, we retrospectively analyzed 113 cases of reverse intertrochanteric fractures in this study and found that irreducible fractures accounted for 67% of reverse intertrochanteric fractures. According to intra-operative fluoroscopy images after closed manipulation, irreducible fractures can be grouped into six patterns. The most common pattern was medial displacement and posterior sagging of the femoral shaft relative to the head-neck fragment. Various techniques were adopted for different patterns of displacement, including the use of a bone hook to pull the femoral shaft, a clamp to reduce fracture fragments, a periosteum elevator to push the head-neck fragment posteriorly, a mallet to lift up the femoral shaft, and a Schanz screw as a joystick. Compared with A3.1-type and A3.2-type fractures, A3.3-type fractures had a higher incidence of irreducibility. Three predictors of irreducibility were identified: a medially displaced femoral shaft relative to the head-neck fragment on the AP view, a displaced lesser trochanter, and a displaced lateral femoral wall. These patients warrant special consideration in terms of recognition and management.
This study was supported by a grant from the Peking University Third Hospital (No. Y62419-06).
Conflicts of interest
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Keywords:© 2019 by Lippincott Williams & Wilkins, Inc.
Intertrochanteric hip fractures; Irreducible; Predictors; Reduction techniques; Reverse oblique