Lesser Trochanter

Psoas This muscle is attached to the vertebral body at a point opposite the center of rotation of the vertebra, so it is attached to the base of the pedicle and the anterior surface of the transverse process. It is inserted at the lesser trochanter of the femur and alters lordosis of the lumbar spine. Hip flexion contractures permit shortening of the psoas, which increases lordosis. Further contracture of the muscle has a tendency to pull the mid-lumbar spine forward and inferiorly. 

The ossification centres for the proximal femur consist of the capital femoral epiphysis, and ossification centres in the greater and lesser trochanters. The capital femoral epiphysis may be cleft or bifid as a normal variant. During development the ossification centres for the greater and lesser trochanters are irregular and often appear separated from the neck and proximal femoral shaft (Fig. 7.30). The distal femoral epiphysis increases rapidly in width between the second and sixth years of life. Irregularity of the lateral and medial margins of the epiphysis is... 

Fig. 7.30a,b. Normal irregularity and apparent separation of the greater trochanter in a 5-year-old boy (a) and lesser trochanter in a 13-year-old boy (b)... 

Intra-operative and post-operative imaging of fractures stabilised with intra-medullary devices requires views in at least two planes, not only to visualise the adequacy of the bone alignment but also to check the position of the implants. Elastic intramedullary nails may appear to be within the bone in one plane but may be seen to lie outside the bone when viewed from a different angle (Fig. 9.4a,b). The nail will have either failed to traverse the fracture site (more common in long spiral fractures) or the sharp tip of the nail will have penetrated the cortex. This is particularly likely around the calcar (femoral neck) and lesser trochanter because the procurva-tum of the femur tends to guide the medial nail in a dorsal direction. Imaging of the hip joint is difficult but crucial to avoid this mistake. 

Fig. 12.24. Sites of pelvic avulsion injuries. A, iliac crest (abdominal muscle insertion). B, anterior superior iliac spine (sartorious muscle origin). C, anterior inferior iliac spine (rectus femoris origin). D, greater trochanter (gluteal insertions). Ey Lesser trochanter (illiopsoas). F, ischial tuberosity (hamstring muscle). G, body of pubis and inferior pubic ramus (adductors and gracillis)...

At the time of birth, the proximal femur is a composite structure containing the greater and lesser trochanters and the femoral head, all as one cartilaginous mass. Ossification of the proximal femur occurs between 4-6 months post-natally. The ossific nucleus is usually visible on ultrasound 2-3 months before it appears on radiographs. The femoral head ossification centre expands, becoming hemi-spherical and the growth plate between the femoral head and the metaphysis becomes clearly identifiable on radiographs as a radiolucent area between the femoral head and metaphysis. 

The iliacus muscle originates from the superior two thirds of the concavity of the iliac fossa, from the inner lip of the iliac crest, from the ventral sacroiliac and iliolumbar ligaments, and from the upper, lateral surface of the sacrum. In front, it reaches as far as the anterosuperior and anteroinferior iliac spines, and receives some fibers from the upper part of the capsule of the hip joint. It inserts into the lateral side of the tendon of the psoas major, which inserts into the lesser trochanter of the femur. 

A major bony landmark is the greater trochanter, easily palpated on the lateral superior aspect of the shaft. The lesser trochanter is on the medial aspect of the inferior end of the femoral neck. This trochanter, although not palpable, is very important, because it is the site of attachment of the iliopsoas tendon. At its distal end, the femoral condyles and epicondyles are easily palpable at the knee joint. 

There are a number of causes for the creation of psoas dysfunction. Among these are trauma to the lumbar spine, lesser trochanter or pubes, myosistis or psoatic bursitis, or visceral dysfunction in relationship to the psoas muscle, such as an acute appendicitis, renal or urethral dysfunctions, fallopian tube inflammation, and iliac or femoral arteiy phlebitis. Any musculoskeletal condition that causes a low back imbalance and lumbar and pelvic somatic dysfunctions must be evaluated. It is important lhat any and all of the findings be actively treated. 

Abstract— Osteoporotic patient has low bone quality and often occur unstable fracture. Conventional dynamic hip screw method can provide good result on stable femoral fracture. On the unstable femoral fracture, it has high failure rate. The purpose is to investigate the biomechanics analysis for dynamic hip Screw on osteoporotic and unstable proximal femoral fracture. The speciflc aims are to (1) develop the osteoporotic and unstable proximal femoral fractures model,(2) investigate the influence of lesser trochanter fixation on stress and deformation distribution. 

This study total reviewed 130 patients treated hy dynamic hip screw surgery and classified the fracture according to AO system. Statistic data showed that the common unstable femoral proximal fracture type is A2.1 (AO classification). The osteoporotic femur model of finite element method (FEM) was developed from the CT image of 80 years patient. Loading condition assigned single-leg stance. The FEM analytic result show the lesser trochanter has a moment of rotation in dynamic fixation without wires fixation condition. Using wires to fix the lesser trochanter can enhance the structure stiffness and reduce the stress distribution in unstable intertrochanter fracture (A2.1 type). 

Osteoporosis is a major public problem, it is a skeletal disease characterized by low bone mass and microarchitec-tural deterioration. Osteoporotic patient occur fragility fracture frequently, and the common positions were vertebral, hip, wrist. There was 1.66million hip fracture in worldwide [1], 1,197,000 in women and 463,000 in men. Dynamic hip screw was the standard treatment in stable femoral proximal fracture. But in unstable fracture, it has high failure rate. Unstable fracture has the weak structure, it cause that the force loads on femoral head. Then the cut-out complication will happen, especially on osteoporotic patient. The hip biomechanics can help us to design new device and develop new technique to solve the clinical problem. From the diagram of the lines of stress in the upper femur, the lesser trochanter supply the compression... 

Type A2 fracture has a fracture line pattern identical to that Type A1 fracture however, the medial cortex is multifragments. It is subdivided into A2.1 fracture, with one intermediate fragment(lesser trochanter) A2.2 fracture, with two fragments and A2.3 fracture, with more than two intermediate fragments. Clinical A2.2 and A2.3 is difficult to identify. In this study is combined to count. 

Type A3 fracture is characterized by a line that passes from the lateral femoral cortex below the greater trochanter to the proximal border of the lesser trochanter often there is also an undisplaced fracture separating the greater trochanter. A3.1 fracture is reverse intertrochanteric fractures (with an oblique fracture line) while A3.2 fracture is transverse (intertrochanteric). A3.3 fracture involves the detachment of the lesser trochanter, and is notoriously difficult to reduce and stabilize. 

Fig. 1 Three wire fixation methods Fixationl has 2wires, upper wire passes across from greater trochanter to lesser trochanter above, lower wire across greater trochanter bottom to lesser trochanter below. Fixation2 also has 2 wires, upper wire passes across from greater trochanter bottom to lesser trochanter above and lower wire passes across from greater trochanter bottom to lesser trochanter below. Fixations has 1 wire, it passes across cross from greater trochanter bottom to lesser trochanter below...

In total deformation result, the arrows show the direction of movement on force loading and the color show that the magnitude. The total deformation result of DHS fixation without wires showed the migration of lesser trochanter was award dovra (Fig. 3), and the femur head have a rotation clockwise moment. The lesser trochanter fixation may maintain the contact of fracture surface and against the head part migration. Then, the wire fixation method was defined according to the goal of lesser trochanter movement and clinical experiment. 

Fig. 3 Type A2.1 femur fixation on Dynamic hip screw fixation without wires FEM analytic result. Arrows show the femur head and lesser trochanter migration...

In this study, the statistic result showed that the common unstable fracture was TypeA2.1. This fracture type character has three fragments, lesser trochanter fragment make the structure instability. The conventional treatment was only DHS fixation. In instability condition, the femur head has bear the larger force. In the lower bone mass situation, it s easily occur cut-out [5]. The migration of femur head showed the lesser trochanter movement direction. And the FEM von Mises result showed the Max. stress of femur head appears in superior of lager screw. 

Fig. 12.2. Anatomy of the anterior muscles and tendons of the hip. Schematic drawing of an anterior view through the hip illustrates the relationships of the anterior muscles to each other. The superficial tensor fasciae latae (Tfl) and sartorius (Sfl) arise from the anterior superior iliac spine (straight arrow). On a deeper plane, the rectus femoris (Rf) originates from the anterior inferior iliac spine (arrowhead). Observe the iliacus and the psoas muscles which join distally to insert through a common tendon onto the lesser trochanter (curved arrow). Medially to the iliopsoas tendon, the pectineus muscle (Pe) can be seen arising from the anterior aspect of the superior ramus of the pubis (Pb)...

Into the upper portion of the pectineal line below the lesser trochanter. 

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