Reinforcement of the second buttressing point Adams arch and calcar femorale

5.3.1 Problems of stability at the second buttressing point

Following the principle of the two-arm lever the greater the part of the Adam's arch and the calcar femorale remaining attached to the caudal fragment the more stable will be the internal fixation. If the buttressing point of the caudal screw that is the pivot of the lever lies more cranial, the length of the lever arm to which force is applied increases (distance between pivot and lateral cortex). To compensate for the body weight applied to the shorter load arm a 2 mm two-hole plate acting as a tension band is attached at the third point of buttressing. The plate counteracts forces pushing the femoral head into varus.

For similar reasons intramedullary nails (Ender-, Gamma-) are biomechanically sounder for the stabilization of trochanteric fractures than extra-medullary implants (DHS, 95° and 130° blade-plates) because they medialize the pivot (see Fig. 15c).

In vertical Pauwels-III fractures the short part of Adam's arch is further away from the femoral head. The load arm becomes longer and the lever arm to which the force is applied is shortened. This results in an increased loading at the third buttressing point (see Fig. 211c-g). In this instance a more vertical placement of the implant is indicated (Brittain, 1942; Garden, 1961b). This solution has, however, the disadvantage that no place remains for the second (cranial) screw next to the craniocentral position of the caudal screw. A vertical position of the caudal screw is also undesirable, as although the shear moments causing a varus displacement decrease, the compression loading increases proportionally on the already circulatory compromised femoral head and on the fracture surfaces (see Figs. 28, 33 and 34). An increased risk of avascular necrosis will result.

If Adam's arch is completely broken off from the caudal fragment or if a multifragmentary or comminuted fracture is present, the second point of buttressing is "absent" leading to a one-arm leverage. The forces acting on the lateral cortex increase and need to be compensated by an angle-stable implant.

In this case an internal fixation with a DHS could be considered as it is done in many trauma centers abroad. Irrespective of the fracture type this implant is used in patients younger than 60 to 65 years (recently younger than 75 years) in those centers where a total joint replacement in patients older than 65 resp. 75 years is always preferred (Bonnaire, 1998).

We always attempt to improve internal fixation with cannulated screws. In our opinion internal fixation of femoral neck fractures with DHS is barely suitable given their many disadvantages:

(1) Some investigations showed that a single large implant damages the femoral head more than multiple small ones (Brodetti, 1960; Nyiri and Rupnik, 1998). Even the strong two-hole plate, part of the DHS is oversized for neck fractures.

(2) During insertion of a large tap and screw the freely movable femoral head can be twisted without additional fixation and damage further the circulation. If the DHS is inserted into the center of the neck as stipulated in the original description, it cannot prevent a rotational displacement. It even acts as an axis around which the femoral head can turn. For this reason, internal fixation with a DHS must be complemented by a cancellous bone screw inserted cranially.

(3) During internal fixation with a DHS the screw cannot be placed in close contact with Adam's arch (as it can cut into it) nor in the subchondral bone on account of its thread diameter. Consequently, the implant must be placed in the center of neck and head. Particularly in older patients it does not rest on Adam's arch and does not find sufficient purchase in the femoral head. A loss of reduction may ensue.

(4) In the above mentioned centers internal fixation with a DHS (complete with the two-hole plate) is performed through a small transmuscular approach. The advocates believe that the inva-siveness of this method does not exceed the in-vasiveness of the cannulated screw insertion. To accomplish the insertion technique of a DHS the

Comminuted Fracture Femur Neck

Fig. 141. Three examples of early complications after DHS internal fixation of femoral neck fractures.

These radiographs were collected during studies abroad.

(1) 89-year-old woman; a. Right Garden-IV comminuted fracture; b. initial treatment with DHS. The screw has been positioned in the cranial third of the head; c. After one week the screw perforated the femoral head followed by a loss of reduction necessitating a hemiarthroplasty.

(2) 68-year-old woman; d. Left femoral neck fracture treated initially with DHS. The screw has been placed in the center of the head, not subchondral; e. After 6 weeks loss of reduction. A total hip replacement was done.

(3) 63-year-old patient; f. The right-sided neck fracture was initially treated with DHS and cancellous bone screw. The threads of the cancellous bone screw crossed the fracture gap causing a diastasis interfering with consolidation; g. Three months after accident a loss of reduction occurred with breakage of the cancellous bone screw

Fig. 141. Three examples of early complications after DHS internal fixation of femoral neck fractures.

These radiographs were collected during studies abroad.

(1) 89-year-old woman; a. Right Garden-IV comminuted fracture; b. initial treatment with DHS. The screw has been positioned in the cranial third of the head; c. After one week the screw perforated the femoral head followed by a loss of reduction necessitating a hemiarthroplasty.

(2) 68-year-old woman; d. Left femoral neck fracture treated initially with DHS. The screw has been placed in the center of the head, not subchondral; e. After 6 weeks loss of reduction. A total hip replacement was done.

(3) 63-year-old patient; f. The right-sided neck fracture was initially treated with DHS and cancellous bone screw. The threads of the cancellous bone screw crossed the fracture gap causing a diastasis interfering with consolidation; g. Three months after accident a loss of reduction occurred with breakage of the cancellous bone screw

Multiple Cancellous Screws

Fig. 142. Anchorage of both screws with one 2 mm two-hole plate each.

80-year-old woman; a. Six days earlier the patient suffered a right Garden-III-Pauwels-III neck fracture in the Ukraine. She was treated conservatively without thrombosis prevention. Her relatives requested an admission to our institute. On account of her poor general health we opted in favor of a cannulated screw fixation in spite of the fact that the fracture was not fresh; b, c. Both screw ends were attached to a 2 mm two-hole plate each to obtain percutaneously a stability as great as possible. The fracture gap remained slightly distracted, the cranial screw reached under the contour of the femoral head as otherwise no place was available for the two plates. Four days postoperatively a pulmonary embolism occurred necessitating the transfer to a cardiac intensive care unit because of her poor general health. Her conditions improved and she could be mobilized later on; d. Three months postoperatively she was able to attend a follow-up. Increasing hip pain was attributed not only to a marked backing-out of screws but also to a perforation of the cranial screw into the joint; e. The DS intraosseous venography was not optimal (marked congestion, metaphyseal drainage, the contrast agent had flowed through the screws into the soft tissues); f. Considering the recent severe illness only a removal of both plates and change of screws was possible. After 3 months of satisfactory evolution and mobilization the patient felt a sudden cracking of her operated hip and was unable to walk; g. The radiograph showed a diastasis of the initial fracture line without loss of reduction (nonunion). It is likely that the patient was weight bearing on her necrotic femoral head (in retrospect a difference in density between femoral head and metaphysis can be recognized in f. At this moment her general health permitted a total hip replacement. Thanks to the minimally invasive internal fixation and revision surgery the elderly and seriously ill patient could be kept alive and improve her condition to allow a total hip replacement. This procedure would have been indicated initially but was precluded by her poor general health

Women Health Hip Arthropalsty Poor Hip Fracture Reduction

Fig. 143. Anchorage of two screws in a 2 mm three-hole plate.

46-year-old woman. Eight months before her first admission to hospital for a right mastectomy for breast cancer followed by radiotherapy for metastases in the first lumbar vertebra and other bones. At the day of admission she felt a cracking in her left hip; a. A pathologic basal neck fracture was diagnosed and treated with a DHS. During the next three months the patient walked with two canes, but then experienced a similar event; b. She suffered a pathologic right Garden-III neck fracture. We opted in favor of a can-nulated screw fixation given her general condition and the fracture configuration. Both screw ends were attached to a 2 mm three-hole plate; c. Six weeks later, she was able to use a walker with full weight bearing, the hip was pain free c

Fig. 143. Anchorage of two screws in a 2 mm three-hole plate.

46-year-old woman. Eight months before her first admission to hospital for a right mastectomy for breast cancer followed by radiotherapy for metastases in the first lumbar vertebra and other bones. At the day of admission she felt a cracking in her left hip; a. A pathologic basal neck fracture was diagnosed and treated with a DHS. During the next three months the patient walked with two canes, but then experienced a similar event; b. She suffered a pathologic right Garden-III neck fracture. We opted in favor of a can-nulated screw fixation given her general condition and the fracture configuration. Both screw ends were attached to a 2 mm three-hole plate; c. Six weeks later, she was able to use a walker with full weight bearing, the hip was pain free use of a T-shaped aiming device attached to the lateral cortex is required; it cannot be inserted through a small approach. Therefore, a freehand technique is often employed. If the proper angle is not respected, a perfect adaptation of the massive plate on the femoral cortex is impossible. Should nevertheless an adaptation with cortical screws be attempted, a strain in the femoral head will result and may lead to a cutting out of the screw from the porotic head (Fig. 141).

(5) As proven by our series the use of cannulated screws for internal fixation is a flexible method that can be adapted during surgery to prevailing conditions, even if the original radiographs failed to reveal a multifragmentary fracture or the severity of osteoporosis.

(6) Also for financial considerations the use of a single set of instruments and implants for the stabilization of various types of femoral neck fractures is not insignificant.

5.3.2 Improvement of the stability of internal fixation with a 2 mm three-hole plate attached to both screw ends

From the beginning our goal has been to be able to individualize an adequate but stable fixation for the heterogeneous forms of neck fractures.

For Garden-I fractures impacted in good position a simple fixation with two screws is sufficient. For Garden-II fractures as well as for the more frequent but not too vertical Garden-III and -IV fractures with intact Adam's arch we routinely use a small caudal 2 mm two-hole plate. In instances where the buttressing effect of Adam's arch has "been lost" (vertical fracture line), in the presence of comminuted or basal neck fractures an additional augmentation of stability is mandatory.

To stabilize Pauwels-III fractures in high-risk patients we attach booth screws each to a 2 mm two-hole plate (Fig. 142).

For similar indications we used repeatedly a three-hole plate that took hold of the two screws (see Figs. 135c and 241b). The possibility to insert this plate percutaneously without enlarging the approach is a major advantage of this technique. The simultaneous attachment of both screws also a b c allows to guarantee their parallel placement. Moreover, this set up protects against micromovements, tilting in varus and foremost against rotation. Apre-requisite of this technique is however the parallel insertion of the screws (Fig. 143).

5.3.3 Improvement of stability of internal fixation of Pauwels-III fractures in combining screws of different thread lengths

For the fixation of Pauwels-III fractures in which cranially a small and caudally a large neck fragment remains in continuity with the femoral head, the use of screws differing from the standard screws with either shorter or longer thread lengths can be necessary. The 24 mm thread length of a standard screw inserted cranially exactly into the subchondral bone will cross the fracture gap and reach into the caudal fragment, thus enlarging the gap possibly interfering with consolidation. On the other hand, it is advantageous to use caudally a screw with longer threads. Therefore screws are available with thread lengths of 24 mm (standard screw), 18, 34 and 44 mm (Figs. 144 and 145).

Internal Fixation The Pelvic

Fig. 144. Screws with different thread lengths.

Adams Arch

Fig. 145. Clinical example of the use of screws with longer threads.

67-year-old woman complaining about right hip pain for several months. Conservative treatment was unsuccessful. Family physician requested radiographs; a, b. A pseudarthrosis after basal neck stress fracture was diagnosed. It was most probably "stabilized" over an extended period by a spur of Adam's arch and calcar femorale; c, d. During internal fixation the fracture gap was perforated several times by drilling. Insertion of two cannulated screws with a 34 mm thread and a double Dynamic Collo-Diaphyseal (DCD) plate (see Fig. 192e, 5.). Nevertheless, a fracture gap remained due to the scar tissue; e, f. Six months later the gap has disappeared. Due to satisfactory settling the fracture consolidated, the patient can weight bear and is symptom free

Fig. 145. Clinical example of the use of screws with longer threads.

67-year-old woman complaining about right hip pain for several months. Conservative treatment was unsuccessful. Family physician requested radiographs; a, b. A pseudarthrosis after basal neck stress fracture was diagnosed. It was most probably "stabilized" over an extended period by a spur of Adam's arch and calcar femorale; c, d. During internal fixation the fracture gap was perforated several times by drilling. Insertion of two cannulated screws with a 34 mm thread and a double Dynamic Collo-Diaphyseal (DCD) plate (see Fig. 192e, 5.). Nevertheless, a fracture gap remained due to the scar tissue; e, f. Six months later the gap has disappeared. Due to satisfactory settling the fracture consolidated, the patient can weight bear and is symptom free

5.3.4 Angle-stable Dynamic Collo-Diaphyseal (DCD) plates for "absent" Adam's arch

If Adam's arch, being the second buttressing point, cannot support the implant, the two-arm lever becomes a one-arm lever and the third buttressing point, being the lateral cortex, will be overloaded. This happens in:

- The presence of multifragmentary or comminuted fractures;

- Pauwels-III and base of neck fractures;

- Some pathologic fractures (neck metastasis);

- Fractures in the presence of coxa vara often due to stress;

- Trochanteric fractures.

In these instances the missing buttress must be replaced. Only a strong reinforcement of the third buttressing point can neutralize the strong displacement force that is due to the action of the body weight on the one-arm lever. For this reason we designed a set of implants consisting of thin plates in three sizes that can be combined with the cannulated screws. The following are the advantages of these plates:

- They allow a sliding of the screws necessary to compensate for the neck shortening secondary to settling;

- They maintain the screw position in the proper collo-diaphyseal angle in spite of the missing Adam's arch;

- They can be flexibly adapted to the degree of fracture instability thanks to additions;

- If necessary, a compression of the fracture can be obtained with a small screw (see Fig. 192d);

- Their insertion is technically easy.

The need to expose the lateral aspect of the femur for proper plate placement is a definite disadvantage.

The DCD plates are placed over the caudal screw after proper aiming and drilling. Depending on the required stability three- and five-hole plates are available having a plate barrel angle of 120°, 130° and 140° (see Figs. 192 and 241h). Thanks to the selection of a proper size femoral neck fractures with coxa vara (not infrequently stress fractures) can also be treated.

The barrel of the DCD plates allows a sliding of screws during settling of the consolidating fracture. Contrary to the DHS the 5 mm long square section preventing rotation does not lie in the cranial but in the caudal part of the barrel (see Fig. 192f); it corresponds to the lateral flattening of the cannulated screw. With the help of a screw (compression screw) that fits into the caudal end of the cannulated screw a careful compression of the fracture can be achieved (Fig. 146).

To further increase the stability a satellite plate can be attached to the DCD plate that holds the cranial screw. The satellite plate fixes the cranial screw and protects foremost against rotation and tilting in varus (Fig. 147, see Figs. 192b, e and 241i).

In instances of severe instability such as in comminuted neck fractures, double fractures and revision surgery, a double angle-stable DCD plate is available, it allows insertion of both cannulated screws and thus a secure fixation. The cranial angle stable part of the DCD plate serving to hold the cranial screw has an oval hole. It is pushed over the barrel of the caudal part of the double DCD plate. The cranial part is available in 120°, 130° and 140° (Fig. 148, see Figs. 192c, e and 241j).

Internal Fixator ImageCoxa Vara Angle

Fig. 146. Simple DCD plate. Impaction of a distraction-stress fractures and coxa vara.

56-year-old woman. She performed strenuous work in her garden three weeks before admission and felt slowly increasing pain in her left hip. Two weeks later she was unable to walk. The family physician requested radiographs; a, b. A diagnosis of a distraction-stress fracture of the neck with coxa vara was diagnosed; c, d. After a short preparation we treated the fracture with two cannulated screws after exposure of the lateral femoral cortex. The distal screw was attached to a DCD plate. As at that time we did not have attachment plates with an angle smaller than 135°, we had to bend the plate to fit it to the coxa vara. With a small screw inserted over the plate we also achieved a compression. The patient bore weight for 9 months, initially with a walker, then with a cane. Instead of decreasing her hip symptoms became more pronounced; e. Radiographs showed a delayed union and a slow bending of the caudal screw. Revision surgery was done and the fracture site was perforated several times with a 3.2 mm spiral drill bit; f. The standard screw was changed for a 9.5 mm screw and the plate for one with 120° that was specially made for this purpose. The fracture was put again under compression. The removed caudal cannulated screw was bent at the junction with the plate and partially broken (this was one of the three patients with screw breaks in 3185 screw fixations); g. Six months later the patient was symptom-free and the fracture had consolidated

Adams Arch

Fig. 147. DCD plate and satellite plate.

57-year-old woman. She fell at her place of work (office) and injured her left hip; a, b. Garden-IV neck fracture considered by us as very unstable, Adam's arch was detached and posterior fragments avulsed (arrows); c, d. For this reason we complemented the cannulated screw fixation with a DCD and satellite plates (10 hours after the accident). The patient returned to her office work two months later; e. Radiographs taken after six months show a consolidated fracture in good position - after settling of the fracture c d e

Fig. 147. DCD plate and satellite plate.

57-year-old woman. She fell at her place of work (office) and injured her left hip; a, b. Garden-IV neck fracture considered by us as very unstable, Adam's arch was detached and posterior fragments avulsed (arrows); c, d. For this reason we complemented the cannulated screw fixation with a DCD and satellite plates (10 hours after the accident). The patient returned to her office work two months later; e. Radiographs taken after six months show a consolidated fracture in good position - after settling of the fracture

Fig. 148. Double DCD plate for a subtrochanteric fracture used in revision of a previous neck fracture.

82-year-old woman. Several previous fractures: left femoral neck fracture, left subtrochanteric fracture, left olecranon fracture, fracture of the right, lateral tibial plateau are witness to her severe osteoporosis; a, b. Patient fell on the day of admission and suffered from a right Garden-II neck fracture with slight varus displacement. Treatment with cannulated screws; c, d. On account of the severe osteoporosis we also applied a standard 2 mm plate. The reduction was not perfect, the Garden-II fracture became displaced and the traction was inadequate. Five weeks later the patient fell out of the bed at home and injured again her right hip. As she complained about pain of both hips, (the left one still painful after an earlier subtrochanteric fracture) and as the patient could not be mobilized, no physician was consulted for six weeks; e. The scheduled follow-up radiograph showed a remote right subtrochanteric fracture; f, g. During the revision surgery we replaced the standard screws with 9.5 mm screws and attached them to a double DCD plate; h. Follow-up after six months revealed a consolidation of the subtrochanteric fracture, the patient ambulates with a walker with some discomfort

Pathelogical Hip Fracture
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