Two Smith-Petersen nails + "distant" plate + sliding screw
Immediate weight bearing with walker
(4) It is important to properly drill the hole in the lateral cortex and to use a buttressing side plate.
(5) The dimension of the applied metal implant should be kept at an optimal minimum necessary for a reliable internal fixation. The distance between plate and buttress (Adam's arch), that is the lever arm to which the force is applied, is considerably greater than the distance between the center of the head and Adam's arch that is the load arm. For this reason, a small buttressing side plate is sufficient for an adequate tension band effect in the majority of neck fractures and it is therefore not necessary to use a massive plate as in instances of trochanteric fractures, where the plate compensates foremost for the broken Adam's arch.
(6) The goal is to obtain a stability that allows the elderly patient an early postoperative mobilization with weight bearing. Consequently, the barely enforceable use of crutches can be omitted. In this way the internal fixation shares all the advantages of a joint replacement, but with a considerably lesser surgical trauma.
Internal fixation with two Smith-Petersen nails combined with a "distant" sliding screw side plate meets all these requirements. This combination was the result of the above described development and was used for one decade as a standard intervention. A marked decrease in the incidence of loss of reduction resulted from this modification (Table 1).
Already in the sixties the treatment of neck fractures in 50 to 60 year-old patients and also in adolescents and children was done by screw fixation. Driving nails into the compact bone is difficult and is accompanied by a very extensive damage to the bone. On the other hand, screws can be introduced with less damage thanks to predrilling and tapping. The screws are sufficiently stabilized in the relatively solid bone. The introduction of cancellous bone screws further increased the stability (Manninger et al, 1970; Manninger et al, 1985).
The rule also applies here that a single implant does not protect sufficiently against loss of reduction in rotation. However, the insertion of several screws has its own problem in that it is difficult to place the screws in a parallel fashion in the narrow neck using a free-hand technique. Any divergence or convergence of screw placement precludes im-
paction/resorption (settling) and thus leads to a delayed or nonunion.
In the eighties we introduced in our institute a parallel guide for parallel placement of three screws to counteract this problem. This guide is fixed to the lateral cortex with a guide wire placed in the center of the neck. Holes in the guide ensure a parallel drilling, tapping and later insertion of the screws after removal of the guide. To reinforce the lateral buttressing of the screw head we designed a plate with "reversed keyholes" that was inserted from cranial over the screw heads and pulled down before tightening the screws. This plate was attached to the femur with one cortical screw. Thanks to the caudal cancellous screw lying in contact with Adam's arch a tension band effect was obtained and protected against loss of reduction in varus. The three screws together with the plate protected against a loss of reduction in rotation (Fig. 124).
We used this technique foremost for the treat-
Fig. 124. Internal fixation with three cancellous bone screws and plate with reversed keyholes.
50-year-old patient who suffered one year previously a left hemiparesis secondary to occlusion of the internal carotid artery. She fell on the day of admission and hit her right hip; a, b. Films in both planes show a Garden-I fracture with slight valgus position and anteversion. A small bony fragment is also seen at the posterior aspect of the neck. Since the right hip was exposed to greater weight bearing due to her stroke, we decided in favor of surgery; c, d. The fracture was stabilized with three cancellous bone screws and a keyhole plate. The patient was mobilized after a few days; e, f. 5 years later the fracture healed with a shortening of the neck, the function was good a c e b d
Fig. 124. Internal fixation with three cancellous bone screws and plate with reversed keyholes.
50-year-old patient who suffered one year previously a left hemiparesis secondary to occlusion of the internal carotid artery. She fell on the day of admission and hit her right hip; a, b. Films in both planes show a Garden-I fracture with slight valgus position and anteversion. A small bony fragment is also seen at the posterior aspect of the neck. Since the right hip was exposed to greater weight bearing due to her stroke, we decided in favor of surgery; c, d. The fracture was stabilized with three cancellous bone screws and a keyhole plate. The patient was mobilized after a few days; e, f. 5 years later the fracture healed with a shortening of the neck, the function was good ment of displaced fractures in younger persons or for the stabilization of Garden-I and -II fractures. In several studies we could prove that well placed screws produce a reliable stability; no loss of reduction was observed (Manninger et al, 1990; Cserhati et al, 1996).
The greatest advantage of this technique in instances of undisplaced fractures in the elderly was the elimination of the aggravating three-week confinement to bed and the three-month use of crutches, both being part of the conservative treatment. Similar to the patients treated for displaced fractures with the Smith-Petersen nailing, these patients can weight bear with cane or walker a few days after surgery without running the risk of loss of reduction.
From the static standpoint our methods, double nailing or fixation with three screws, has also responded to the requirements of internal fixation. Chiseling, insertion of the nail by hammering, application of the parallel guide and insertion of the plate with key holes were time consuming and could only be executed by a precise retromuscular approach. This led to a lengthening of the operating time and an increased stress for the older patient. Consequently, a longer preoperative preparation became necessary (availability of blood transfusions) and forced us frequently to exceed the 6-hour limit before surgery.
A percutaneous insertion of screws could constitute the method that would also be advantageous for the patient from the biologic aspect. However, the screws available up to this moment did not seem to guarantee the necessary parallel insertion. Besides, the stability obtained, particularly in rotation, could not match that of two Smith-Petersen nails that allowed also a reliable fixation of displaced fractures. This situation changed dramatically with the introduction of cannulated cancellous bone screws. Their parallel insertion was guaranteed by using guide wires.
In 1987, Professor C. Olerud presented the use of two percutaneously inserted cannulated screws at our institute. Screws and instruments were designed by his group (Rehnberg and Olerud, 1989;
Olerud and Rehnberg, 1991; Olerud and Rehnberg, 1993; Olerud et al, 1995). This so-called Uppsala technique, known to us from the thesis of Rehn-berg (1988) resembled in some aspects the techniques developed by us: the nailing with two Smith-Petersen nails and the fixation with three cancel-lous bone screws combined with the keyhole plate. Also in these techniques the strictly parallel insertion of screws and the importance of compensation for resorption had been emphasized. The new method was a step in the right direction for two reasons: a less invasive approach and a more stable internal fixation. On one hand, parallel guide and guide wires allowed a reliable parallel insertion of the cannulated screws through a smaller incision. On the other hand, advancing the screws into the subchondral bone of the femoral head led to a better purchase also in the hope of a better hold in severely osteoporotic bone.
In November 1990, we performed the first two insertions of the original Swedish implants. In the following year we added another ten implantations. In our opinion the subchondral stability of the screws and the shorter operating time are two outstanding advantages. We attempted from the beginning to use our past experience in the development and clinical use of earlier methods to incorporate them into the new technique.
The lateral buttressing was not part of the original Swedish method. In the first two cases we attached the lateral screw ends to a modified one third tubular plate. As its placement met technical difficulties, we constructed a small side plate exerting a tension band effect, mostly to prevent a tilting in varus (see Fig. 241a). Rectangular holes contributed to a certain rotational stability. During the development of the plate we perfected the percutaneous insertion and the relevant instruments. Up to the moment of the introduction of this plate we performed the internal fixation only with two screws. During that time we observed on radiographs in a considerable number of these patients a slight displacement in varus and rotation after mobilization of the patient (Fekete et al, 1992).
The necessity arose to adapt the screw shank to the rectangular holes of the small plate and to flatten its end over a longer distance to preserve the stability without interfering with the sliding. To compensate for this flattening we increased the shank diameter to 7 mm. This stronger shank also allowed to insert larger compression screws. At the same time this prevented a migration of the cannu-lated screw in a superomedial direction (see Fig. 192d). We also deepened the threads and removed the spikes at the tip of the cancellous bone screw to increase the subchondral purchase. In addition, we designed holes between the threads and two longitudinal grooves at the surface of these screws to improve the drainage of the congested blood in the femoral head (see Fig. 57).
We also modified considerably the surgical technique. During the earlier performed open reductions we observed that the tip of the guide wire slipped off the bone and displaced the femoral head, particularly in younger patients. For this reason we perform now a predrilling with a 3.2 mm spiral drill bit.
For a more stable fixation of porotic, certain subcapital or vertical fractures (Pauwels-III) as well as for basal neck fractures we use screws with a greater thread diameter (9.5 mm) and thread lengths of 18, 34, and 44 mm (standard length 24 mm) (Fekete et al, 2000b; Fekete et al, 2000c). For the internal fixation of neck fractures in younger patients where MRI and CT follow-up examinations are necessary, we also use titanium implants (Melly et al, 1999) (see Fig. 189).
We discussed repeatedly certain modifications with representatives of the manufacturer. We wanted to make sure that our wishes based on experience are respected permitting us the introduction of cannulated screws. As our efforts were not successful we approached the Hungarian company Sanatmetal. Over many years this company had manufactured for us numerous implants of reliable quality with the result that our cannulated femoral neck screws are made in Hungary from imported cannulated steel rods (Sandvik®).
We tested the majority of developed implants before their clinical use in cadaver specimens at the Department of Material Science and Mechanics at the Budapest University of Technology and Economics (BUTE) (see chap. 5) and patented them (Patent number 85256, valid to 2007).
The collaboration of medical doctors and engineers at the National Institute of Traumatology
(Budapest), the members of the BUTE and the development engineers of the manufacturer led to numerous new and considerably modified implants and instruments. Our research and development was also supported by grants from the Hungarian Ministry of Health (ETT) and the Hungarian Academy of Science (OTKA) (Project Nr. ETT 140/1993, 103/1996, 426/2000, 254/2003, 344/2003, OTKA 970/1991, F6193/1992, T016341/1995, T024006/1997, T034680/2000).
The following short summary lists the most important new models and modifications for the internal fixation with standard screws:
- The shank of the neck screw was increased to 7 mm to ensure that the flattening of the shank's end would not weaken the implant. This, in turn, allows a dynamic auto-compression secondary to impaction/resorption (settling) as well as fixation ensuring rotational stability thanks to a small straight side plate having a tension band effect.
- The tip of the screw is blunt; the threads reach the tip and are self-cutting.
- The other end of the cannulated screw has a bore (0 5 mm) with threads in the metric system. Another long screw is inserted into the T-handle and screwed into the cannulated screw. This allows a secure hold of the T-handle. The 5 mm bore can also be used for a stronger compression screw.
- The accumulated intraosseous blood can drain through four holes made between the threads and two longitudinal grooves in the shank. This is the principle of the "draining screw".
- The length of threads is available in four lengths: 18 mm, 24 mm (standard length), 34 mm and 44 mm.
- Thread diameters of 8 mm and 9.5 mm are available.
- The slotted screws can be introduced exacter, faster and simpler through the 10/8 mm sleeve.
- To ensure a parallel insertion of the guide wires two 300 mm long spiral drill bits have been included in the set (0 3.2 mm).
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