External Fixation of Select Intertrochanteric Fractures With Single Hip Screw

Abstract

Since 1994, external fixation using a long hip screw was used for osteosynthesis of trochanteric fractures in 41 patients (27 women and 14 men) 76 to 94 years of age (mean age, 85 years) to minimize the risks associated with an open surgical procedure and general or long lasting spinal anesthesia. The patients were operated on under short duration spinal anesthesia, and intraoperative blood transfusion was not required in any patient. The hip screw was inserted on a guide pin within a protective sleeve in such a way as to achieve impaction at the fracture site as compression was applied in 35 patients. The hip screw was left free for sliding and dynamization in six patients. Diaphyseal distraction by the fixator was used in three of nine unstable fractures to correct varus deformity. The range of times to apply the external fixator was 20 to 45 minutes (mean, 35 minutes). The mean hospital stay was 6 days (range, 3–12 days) and the time to fracture union was 12 weeks (range, 11–13 weeks). Five patients died within 3 months. There were no nonunions or deep infections, but in 18 patients superficial skin reactions were seen around the pins and the screw. No material failure occurred. The method is thought to offer easy and safe stabilization of these fractures with the exception of temporary skin problems, which do not create a major problem.

An increase in the longevity of life spans accompanied by osteoporosis and muscular insufficiency may explain the increasing number of patients with intertrochanteric fracture. ^2,5,9 Internal osteosynthesis is a routine procedure for these fractures, but in patients at poor risk with accompanying diseases, such as ischemic cardiac disease, chronic obstructive pulmonary disease, diabetes mellitus, or severe anemia, there is a high risk of anesthetic or postoperative complications. Closed reduction and external fixation is an alternative procedure that may minimize complications and intraoperative blood loss. ^1,3,4,6

A new external fixator, the Citieffe/Ch-N (Fig 1), designed by the senior author and manufactured by Citieffe, Bologna, Italy, stabilizes the intertrochanteric fracture by using a hip screw to offer stabilization of the fracture as in internal osteosynthesis. It is applied easily without open intervention and with minimal blood loss. The hip screw is cannulated and is easily inserted into the femoral neck and head using a guide pin within a protective sleeve in such a way as to permit impaction and thereafter compression at the fracture site as it can be done in most stable fractures. An additional antirotation external fixator pin in the neck of the femur occasionally is needed in fractures that remain unstable after the reduction attempts and in cases in which there is not sufficient contact between the fragments to produce compression (Fig 1D). The long dynamic hip screw also can be left free for sliding and dynamization, depending on the progression of union and on the ability of the patient to bear weight. The fixator also can be used for diaphyseal distraction to correct a postoperative varus deformity or to obtain axial compression.

Fig 1A–E.: The dynamic Citieffe/Ch-N external fixator. (A) Nut used to stabilize the hip screw on the fixator after compression is applied on the fracture or to let the hip screw free for sliding; (B) the upper body of the fixator. It is stabilized on the diaphyseal pins in such a way as to protrude approximately 5 to 10 mm from the external end of the hip screw if compression on the fracture is needed; (C) screw used to achieve compression on the fracture by traction of the hip screw on the fixator, which previously is stabilized on the diaphyseal pins; (D) additional antirotation external fixator pin can be inserted to the neck and the head of the femur in cases of unstable fracture with or without previous compression on the fracture; and (E) mechanism for diaphyseal axial compression, axial distraction, or dynamic axial compression.

MATERIALS AND METHODS

Since 1994 the Citieffe/Ch-N external fixator (Fig 1A–D) was applied to 41 elderly patients, 27 women and 14 men, 76 to 94 years of age (mean, 85 years) selected from 103 patients older than 65 years treated for intertrochanteric fracture (subtrochanteric fractures are not included). The remaining 62 patients were treated with an open surgical procedure. The 41 patients selected for external fixation sustained 42 intertrochanteric fractures; one was treated conservatively. Thirty-two of the 41 (78.1%) fractures treated by external fixation were stable, and nine (21.9%) were unstable according to the classification of Jensen. ⁸

The patients in the external fixation group were selected because of their high surgical and anesthetic risk for an open surgical procedure or for long lasting anesthesia because they had more than one accompanying disease (Table 1). They also were selected for external fixation if there were difficulties of blood collection on the first hospitalization day. Most patients with severe anemia (sickle cell anemia, leukemia, thalassemia) or negative blood Rh factors were included in the external fixation group. Eleven (26.8%) patients of the external fixation group had a hemoglobin level less than 11 g/L, compared with two patients in the internal fixation group. Eleven (26.8%) patients in the external fixation group and five (0.8%) in the internal fixation group had negative blood Rh factors. If blood supplies were not sufficient for an open surgical procedure on the first hospitalization day and there were no limitations for external fixation, the fracture was treated by external fixation. The possibility of pin site care after hospitalization was another factor used to select patients for external fixation. Patients with a body weight of approximately 80 kg or more and patients with colostomy or fecal incontinence were not treated by external fixation.

TABLE 1: Medical Problems in Patients in the External Fixation Group Versus Patients in the Internal Fixation Group

The internal fixation group of patients consisted of the 62 remaining unselected patients who were treated with internal osteosynthesis by using a dynamic hip screw during the same time. Seventeen patients in the external fixation group had ischemic cardiac disease, 16 had pulmonary disease, seven had diabetes mellitus, and 14 had cerebral dysfunction; 39 (95.1%) of them were older than 75 years of age, versus 48 (77.4%) patients in the internal fixation group. Thus, it was difficult to have a precise control group of patients. The internal fixation group of patients was used mainly to compare operation and hospitalization time, blood loss, fracture union, or varus deformity (Table 2). The 62 patients of the internal fixation group, which consisted of 49 women and 13 men, 65 to 93 years of age (mean, 78 years) sustained 64 intertrochanteric fractures, of which 62 were treated by internal osteosynthesis using a dynamic hip screw; two were treated conservatively. Forty-three of the 62 (69.3%) fractures treated by internal fixation were stable and 19 (30.7%) were unstable.

TABLE 2: Clinical Results and 6-Month Mortality Rate in Patients in the External Fixation Group Versus Patients in the Internal Fixation Group

The relationship between the preoperative condition and outcome was examined using ambulation ability and perioperative mortality. The ambulation ability was defined as follows: Group I patients walked without an aid, Group II patients walked with an aid, Group III patients were confined to a wheelchair, and Group IV patients were bedridden. ¹⁰ Prefracture ambulation ability in Group I or II had 36 (87.8%) patients in the external fixation group and 56 (90.5%) patients in the internal fixation group.

The patients were placed on an orthopaedic table using image intensification for surgery and short duration spinal anesthesia. Thirty-seven (90.2%) patients in the external fixation group and 26 (41.2%) patients in the internal fixation group had surgery on the first day of hospitalization. Thirty-two (51.6%) patients in the internal fixation group had surgery the second day of hospitalization, and four (6.5%) patients in this group had surgery after 48 hours or longer. This mainly was because of the patients’ extended preparation for open surgery, such as in patients with fluid imbalance or in those with diabetes mellitus. It also was attributable to difficulties in obtaining adequate quantities of blood for transfusion for an open surgery. An indwelling catheter was inserted in all patients who were incontinent. An indwelling catheter was needed for four patients in the external fixation group and in three patients in the internal fixation group for 15 or more days to avoid contamination of the wound by urine. When the patients who were treated by external fixation were discharged from the hospital, their caretakers were taught how to keep the pins and the screw aseptic. For most of the patients, especially those with skin reaction around the pins and the screw, weekly antimicrobial cleaning and dressing with chlorhexidine gluconate (Johnson & Johnson Medical Inc, Arlington, TX) were used. No other antimicrobial therapy was used on these patients, except for those with pulmonary or other infections.

The Citieffe/Ch-N external fixator for osteosynthesis of trochanteric fractures was designed with a compression system in which the lock compression screw (Fig 1C) is in the axial position compared with the hip screw. The screw traction strain under high performance is 3726 N. The compression limit depends on the quality of the bone, the distance between the pins and the hip screw, and the diameter of the pins. The long hip screw used in this external fixator has geometric features similar to the dynamic hip screw used in internal osteosynthesis, and the rotation stability is within the same parameters. The main device of the Citieffe/Ch-N external fixator, like all external fixators, is not in contact with the bone; thus, the flexion strain is higher than that of the dynamic hip screw plate. The montage of the trochanteric dynamic hip screw plate is more firm. The hip screw of the Citieffe/Ch-N external fixator has the characteristics of the internal osteosynthesis using a dynamic hip screw. It works according to tension band principles and transmits repeated cyclic loads across the fracture site to promote bony union as in internal osteosynthesis. ⁷ It is difficult to do comparative studies with other external fixation systems because the others do not use one hip screw; rather, they use many pins into the head and the neck of the femur with no compression or sliding.

Surgical Technique

With the patient under short duration spinal anesthesia and lying on an orthopaedic table, a closed reduction of the fracture is performed using biplane radiographic control. A guide pin is inserted into the head and neck of the femur through a small skin incision, approximately 3 cm distal to the lateral prominence of the greater trochanter. A protective sleeve is used to protect the soft tissue between the skin and the bone (Fig 2A). The sleeve, which is used to protect the soft tissue, also is used as a counter for the soft tissue thickness between the skin and the femoral bone (Fig 2B). The depth of the appropriate reaming can be calculated with a second counter (Fig 2C) inserted into the sleeve. A stopper fixed to the reamer prevents it from being inserted too far into the bone (Fig 2D). The two counters are used to estimate the length of the appropriate hip screw in such a way to be prominent approximately 8 to 10 cm out of the skin.

Fig 2A–E.: (A) Guide pin; (B) soft tissue protective sleeve and first counter; (C) second counter used to calculate the appropriate reaming; (D) stopper; and (E) reamer.

The hip screw of the external fixator must be inserted into the femoral head, near the joint and the medial cortex according to the principles of the internal osteosynthesis using the dynamic hip screw. In some unstable fractures, a provisional antirotation Kirschner (K) wire must be inserted superiorly into the neck of the femur before reaming and insertion of the hip screw. If compression of the fracture is needed, the wire must be parallel to the hip screw. After reaming, the appropriate hip screw is inserted in the sleeve and advanced into the neck and head of the femur (Fig 3). Two or three 6-mm diameter, self-tapping and self-piercing cortical external fixator pins are inserted into the middle of the femoral shaft at the posterior border of the fascia lata. In cases of osteoporosis and unstable fracture three 6-mm diameter diaphyseal external fixator pins are needed.

Fig 3.: The hip screw inserted to the neck and the head of the femur within the soft tissue protective sleeve.

The upper body of the fixator (Fig 1B) is stabilized on the diaphyseal pins in such a way as to protrude approximately 5 to 10 mm from the external end of the hip screw if compression on the fracture is needed by using the screw for compression (Fig 1C). The stabilizing nut (Fig 1A) can be adjusted to let the hip screw remain free for sliding. Thus, dynamization of the fracture can be achieved during the union process. Compression, distraction, or axial compression parallel to the anatomic axis of the femur can be obtained during surgery or later by a special mechanism of the fixator (Fig 1E). This mechanism works with two clockwise axial nuts for distraction or compression. A spring is included to permit axial dynamic compression similar to some mechanisms used during leg lengthening. Depending on the accuracy of the reduction, an additional antirotation external fixator pin (Fig 1D) can be inserted into the neck of the femur and stabilized on the fixator.

If an unstable fracture remains unstable after the reduction trial, an antirotation external fixator pin must be inserted into the head and the neck of the femur.

Sufficient reduction by traction, flexion, and internal rotation of the hip was achieved in 34 (82.9%) of the patients in the external fixation group and in 49 (79%) of the patients in the internal fixation group. The percentage of unstable fractures was greater in the internal fixation group of patients than in the external fixation group of patients. According to the principles of internal osteosynthesis, with the use of a dynamic hip screw the proper placement of the hip screw into the femoral head, near the joint and the medial cortex, was achieved in 31 (75.6%) patients in the external fixation group and in 42 (67.7%) patients in the internal fixation group.

Compression was applied in 32 stable and three unstable fractures in which the main fragments were in sufficient contact or impaction after the reduction trials. An antirotational external fixator pin inserted into the neck and the head of the femur was used in the rest of the unstable fractures. In six hips, the screw was left free for sliding because there was insufficient new bone formation from the fracture union process 2 months after the fracture occurred. Diaphyseal distraction by the fixator was used in three of the nine unstable fractures to correct varus deformity after surgery. In two patients with osteoporosis, radiographs obtained 1 month after surgery showed the screw was inserted in the hip. During an outpatient procedure, this was corrected easily by the fixator.

RESULTS

The average operating time was 35 minutes (range, 20–45 minutes) after reduction of the fracture in the external fixation group of patients and 75 minutes (range, 40–95 minutes) in the internal fixation group of patients. The mean hospital stay was 6 days (range, 3–12 days) for the external fixation group of patients and 16 days (range, 9–21 days) for the internal fixation group of patients. Fifteen patients in the external fixation group and two patients in the internal fixation group entered a home for the elderly directly after their discharge from the hospital, where they received proper nursing care.

There was no need for intraoperative blood transfusion in any patient in the external fixation group because blood loss was negligible. Five patients in the external fixation group needed 1 unit of blood transfused during the preparation time for surgery because they were anemic. One to 3 units of blood (average, 1.5 units) were needed by all patients in the internal fixation group during or after surgery. Walking with support and partial weightbearing was possible for 30 (73.2%) patients in the external fixation group and 47 (75.8%) patients in the internal fixation group, but all patients were mobilized the day after surgery. Full weightbearing was possible 2 months after surgery in 22 (53.6%) patients in the external fixation group and 37 (59.7%) patients in the internal fixation group because the union process and stability of the fracture was sufficient. Sitting in a chair was possible with this kind of fixator. A routine indwelling catheter was required by four patients in the external fixation group and three patients in the internal fixation group for more than 15 days to avoid contamination of the wound by urine. No patients had permanent stiffness of the knee.

The 6-month postoperative ambulation ability of Categories I or II according to the classification of Kyo et al ¹⁰ deteriorated in 17 (50%) of the 34 surviving patients in the external fixation group and in 24 (47.3%) of the 52 surviving patients in the internal fixation group. It was impossible to compare surgical complications, ambulation ability, or mortality rates between the two groups of patients because of different ages and physical conditions, but in the external fixation group there were no perioperative deaths (during the first 15 postoperative days), whereas in the internal fixation group there were three perioperative deaths. Five (12.1%) patients treated with external fixation who had more than one accompanying disease died within 3 postoperative months, whereas in the internal fixation group, eight (12.9%) patients died during this period. The mortality rate at 6 months was 17.1% (seven patients) in the external fixation group and 16.1% (10 patients) in the internal fixation group (Table 2). The 6-month mortality rate in the external fixation group was smaller than that reported in the literature for this category of patients treated with other kinds of external fixation or internal osteosynthesis. ^1,10

Superficial pressure sores occurred in three patients in the external fixation group and in four patients in the internal fixation group because of inadequate mobilization at home.

All fractures in the remaining patients of the external fixation group were united at approximately 80 to 90 days (mean, 12 weeks), and the fixator was removed easily during outpatient followup. There were no cases of nonunion in the external fixation group of patients among those who survived 6 months after surgery, whereas in the internal fixation group of patients, one nonunion occurred.

No troublesome skin necrosis around the pins and the hip screw or deep infection was seen, but 18 patients had skin reaction around the screw and the pins. After surgery, five of these patients had profuse serous drainage because of soft tissue irritation by the screw without evidence of pin tract infection (microbial cultures were negative). For all patients with skin reaction around the screw and the pins, weekly antimicrobial cleaning and dressing with chlorhexidine gluconate was used. No skin or screw was removed for this reason. Because local microbial cultures were negative, no additional antibiotics were given to the patients. Four of these five patients received antibiotics for treatment of urine contamination. After removal of the fixator, the fracture union being satisfactory, skin healing occurred within approximately 10 days without the use of antibiotics except those given for other accompanying diseases.

In three of the nine unstable fractures, a varus deformity approximately 10° compared with the other hip was corrected after surgery by the fixator. Varus healing, 9° and 11° in comparison with the opposite side, was found in two other patients in the external fixation group. In the internal fixation group of patients, three cases of varus healing were found. In two patients with osteoporosis in the external fixation group, the postoperative radiographs showed that the hip screw was inserted into the hip. This was corrected by manipulation of the fixator. Two patients in the internal fixation group who had symptomatic hip penetration needed an open surgical procedure to remove the screw plate as the fracture union was completed.

DISCUSSION

Open reduction and internal osteosynthesis of trochanteric fractures is the routine procedure, but the morbidity and mortality rates are high, especially in older patients with associated diseases such as ischemic cardiac disease, hemiparesis, cerebrovascular problems, chronic obstructive pulmonary disease, diabetes mellitus, or severe anemia. ^11,12 However, in patients with a high surgical risk, nonoperative treatment involves prolonged immobilization and hospitalization, with many concomitant problems and high mortality.

The operation time and the concomitant blood loss at times experienced with internal osteosynthesis of intertrochanteric fractures prompted a search for an easily applied external fixator for select intertrochanteric fractures. Previous reports with external fixation showed short operating and hospitalization time, high fracture union rates, and minimal surgical blood loss. ^1,3,4,6

The Citieffe/Ch-N external fixator appears to offer some advantages compared with internal osteosynthesis. These advantages are: (1) short duration of anesthesia and surgery; (2) minimal blood loss (especially in patients with severe anemia and rare blood Rh factors); (3) short hospitalization; and (4) the possibility of postoperative correction of a varus deformity or of an insertion of the hip screw into the joint without open intervention. In comparison with other external fixators ^1,3,4,6 that are used for treatment of osteosynthesis of intertrochanteric fractures, the Citieffe/Ch-N external fixator uses in most cases only one hip screw. It mimics the mechanics of internal osteosynthesis using the dynamic hip screw because it can cause compression on the fracture. By adjusting only a nut, it is possible to let the hip screw remain free for sliding during or after surgery. This is impossible with other kinds of external fixators, which use many external fixator pins in the neck and head of the femur.

The main problem in external fixation is the care of the skin until the fracture heals. There is no significant difference between deterioration of ability to ambulate at 6 months in the external fixation group of patients and the internal fixation group, according to Kyo et al. ¹⁰

The mortality rate at 3 months was 12.1% (five patients) in the external fixation group and 12.9% (eight patients) in the internal fixation group, whereas at 6 months it was 17.1% (eight patients) in the external fixation group and 16.1% (10 patients) in the internal fixation group of patients. The 6-month mortality rate in the external fixation group of patients was smaller than that which is mentioned in the literature for this category of patients treated with other kinds of external fixation or internal osteosynthesis. ^1,10

The benefit of minimal blood loss is clear in the patients treated with the Citieffe/Ch-N external fixator or other kinds of external fixators. ¹ Serious stiffness of the knee in the external fixation group of patients did not occur because the diaphyseal pins were inserted into the middle of the shaft of the femur at the posterior border of the fascia lata. In comparison with the dynamic hip screw, the Citieffe/Ch-N external fixator has sufficient compression capability provided by the compression screw of the fixator (Fig 1C), which acts axially in the hip screw. All external fixators have flexion strains higher than that seen in the dynamic hip screw because their main body is not in contact with the bone. In cases of early full weightbearing and an unstable fracture, varus deformity can occur, as it did with five of the nine unstable fractures in the external fixation group of patients. In the internal fixation group, varus deformity occurred in three patients. The only advantage of external fixation in unstable intertrochanteric fractures is that it is possible to correct these deformities, especially in the first postoperative days, without open surgical intervention. In comparison with the other external fixators, the Citieffe/Ch-N external fixator offers the possibility of applying compression on the fracture in addition to sliding and dynamization with a simple adjustment of a nut (Fig 1A) during or after surgery to mimic internal osteosynthesis using the dynamic hip screw. The union of intertrochanteric fractures seems to be assured with external fixation, ^1,3,4,6 including the Citieffe/Ch-N system, which mechanically mimics the internal osteosynthesis using a dynamic hip screw (Fig 4).

Fig 4A–C.: (A) Trochanteric fracture before, (B) during, and (C) after external fixation.

The internal fixation group of patients is not a precise control group but is the group of patients remaining after the selection of patients for external fixation. The good results seen in patients of the external fixation group prompted use of this method in patients who initially were to receive internal osteosynthesis, especially in patients who weighed less than 75 to 80 kg, had a stable intertrochanteric fracture, and whose nursing care was assured at home or elsewhere.

The benefits in cost and time of using external fixation must be calculated with the cost of pin site care and potential need for antibiotics for treatment of superficial wound infection.