With the aging of the population, pertrochanteric femur fractures are among the most serious causes of mortality and morbidity in elderly people, and early surgical intervention is advocated to relieve pain, avoid complications of long-term bed rest and recover self-care ability [3–5]. Short cephalomedullary nails have been more frequently used for unstable intertrochanteric fractures in recent years [6–8]. Regardless of the type of fracture, obtaining a good reduction quality is the goal of the internal fixation of fractures and is one of the most important factors affecting the long-term clinical outcome.
However, some kinds of fractures are not amenable to closed reduction through conventional manipulation, which are referred to as irreducible patterns. The radiological features of irreducible intertrochanteric fractures have been summarized, and classifications have been introduced by several authors. In our clinical practice, we divide these fractures into two categories. The first category involves communicated fractures (four parts, five parts, or more), with the fragments separated from each other and obviously dislocated (coronal plane, sagittal plane and transverse plane), and there is no hinge of soft tissue between the fragments. During the operation, the force induced by traction of the extremity is not transmitted to the head-neck fragment, which may cause difficulty in realigning the fracture site. The second category is related to the structures of the lesser trochanter and iliopsoas. Fractures are often not very comminuted, and obvious bone interlocking and/or soft tissue interlocking occurs, which require the assistance of instruments.
The second group includes the following four subtypes. ①The lesser trochanter is fractured and departed, with the lower tip inserted into the fracture site or distal femoral cavity, which may cause irreducibility. ② The lesser trochanter is connected to a head-neck fragment with traction by the interposed iliopsoas tendon, and the head-neck fragment may be seriously flexed and displaced. ③ The lesser trochanter is connected to the femoral shaft, and the thicknesses of both fracture sites are not equal. ④ The lesser trochanter is bisected equally, with the iliacus muscle interposed between the head-neck fragment and femoral shaft. This is the fracture pattern we discussed in this paper.
There are few reports about this kind of fracture in the literature, which accounts for approximately 3% of the total pertrochanteric fractures and is more common in middle-aged and relatively young elderly people but is rarely found in those over 70 years old (Table 2). In 1996, Moehring et al. [9] first reported 112 cases of intertrochanteric fractures treated surgically, of which 4 cases (3.6%) could not be reduced by conventional traction and closed manipulation. It was found that iliopsoas were interposed between the head-neck fragment and the femoral shaft during the operation. Only after the soft tissue interlocking was removed could the fracture be satisfactorily reduced. Said et al. [12] reported 5 cases of two-part intertrochanteric fractures requiring open reduction intraoperatively. The lesser trochanter was connected to the distal femoral shaft, and the proximal head-neck fragment had a characteristic long pointed apex (including the upper part of the lesser trochanter). Due to the traction of the iliopsoas and gluteus medius, the femoral shaft moved to the front of the hip joint capsule, resulting in clinical swelling in the front of the hip joint. Among the 5 cases, 2 cases had to have the iliopsoas tendon cut from the insertion of the lesser trochanter for fracture reduction. Chandak et al. [13] summarized 924 cases of intertrochanteric fractures treated surgically and found that 20 cases (2.2%) belonged to the irreducible pattern, which were all related to the attachment of the lower part of the lesser trochanter to the distal femoral shaft, resulting in the interposition of the iliopsoas muscle between the fracture sites.
Table 2
Literature data of pertrochanteric fractures with bisecting lesser trochanter
Author, year | Number of cases | Incidence rate | Internal fixation |
Moehring, 1996 | 4 / 112 | 3.6% | DHS |
Said, 2005 | 5 | --- | DHS |
Sharma, 2014 | 6 / 212 | 2.8% | DHS |
Chandak, 2019 | 20 / 924 | 2.2% | DHS |
Our group | 12 / 357 | 3.4% | PFNA, TFNA |
The occurrence of intertrochanteric fractures with bisection of the lesser trochanter may be related to the anatomical insertion of the iliopsoas tendon into the lesser trochanter [17–18]. The iliopsoas tendon is a conjoined tendon. Bartoska et al. [19] dissected 50 specimens and found that the iliopsoas tendon was attached directly to the lesser trochanter in two portions. The first circular portion, which was the attachment of the m. psoas major tendon to the apex of the trochanter minor, while the other longitudinal portion, which included the m. iliacus tendon medially enclosing the insertion of the m. psoas major tendon and projecting distally from the base of the lesser trochanter. Philippon et al. [20] studied 53 specimens and found that the insertion points of the iliopsoas were a single tendon, double tendon and triple tendon, with occurrence rates of 28.3%, 64.2% and 7.5%, respectively (including iliac accessory tendon). The psoas major tendon is always in the most medial position and ends at the apex of the lesser trochanter. Gomez-Hoyos et al. [21] studied the tendinous footprint of the lesser trochanter and found that the iliopsoas tendon footprints in the lesser trochanter were longitudinally oval and distributed in the anteromedial region of the lesser trochanter. There were 3 specimens with a single conjoined iliopsoas tendon, while 7 specimens with a divided attachment footprint were identified for the iliacus muscle and psoas major muscle. The bald area between the tendinous insertion of the psoas major tendon and iliacus tendon was a weak area that was easily fractured, which was the main cause of the bisection of the lesser trochanter.