15 янв. 2012 г.

Сравнительное исследование проксимального бедренного гвоздя с антиротацией и реконструктивного гвоздя при лечении оскольчатых переломов проксимальнеого отдела бедра


Сравнительное исследование проксимального бедренного гвоздя с антиротацией и реконструктивного гвоздя при лечении оскольчатых переломов проксимальнеого отдела бедра (пока без перевода)

ORTHOPEDICS January 2012;35(1):41
by Fu-Ting Huang, MD; Kai-Cheng Lin, MD; Shan-Wei Yang, MD; Jenn-Huei Renn, MD

Abstract

The purpose of our study was to compare the proximal femoral nail antirotation (PFNA; Synthes, Paoli, Pennsylvania) with a reconstruction nail (Recon; Zimmer, Warsaw, Indiana) in the treatment of comminuted proximal femoral fractures. Between 2003 and 2010, twenty-three consecutive patients with AO/Orthopaedic Trauma Association 31-A3 fractures combined with proximal 32 fractures who had a minimum 18-month follow-up were evaluated retrospectively. There were 10 patients (age range, 18-74 years) in the Recon nail group and 13 patients (age range, 22-90 years) in the PFNA nail group. Patients treated with Recon nails experienced a longer operation time (P=.006) and more blood loss (P=.012) than patients treated with the PFNA nail. On postoperative radiographs, the change in the neck-shaft angle was 8.8° in the Recon nail group and 4.7° in the PFNA nail group (P=.048). The fracture union time averaged 31.8 weeks in the Recon nail group and 21.5 weeks in the PFNA nail group (P=.148). More patients in the Recon nail group underwent major or minor reoperation (P=.038) compared with the PFNA nail group. No implant failure occurred in either group. The functional results were similar in the 2 groups. For the treatment of comminuted proximal femoral fractures, use of either the PFNA and Recon nail is clinically effective. However, the PFNA nail provides a shorter operation time, less blood loss, and better realignment ability and reduces the incidence of reoperation. Therefore, the PFNA nail can be considered a better device than the Recon nail

.

Drs Huang, Lin, Yang, and Renn are from the Department of Orthopedics, Kaohsiung Veterans General Hospital, Kaohsiung City, Taiwan.

Drs Huang, Lin, Yang, and Renn have no relevant financial relationships to disclose.


Correspondence should be addressed to: Fu-Ting Huang, MD, Department of Orthopedics, Kaohsiung Veterans General Hospital, 386 Ta-Chung 1st Rd, Kaohsiung City, Taiwan 81346 R.O.C. (fthuang@vghks.gov.tw).
Posted Online: January 16, 2012

Comminuted proximal femoral fractures are not common. They result from high-energy trauma mechanisms, including motor vehicle traffic accidents and falls from heights. 1 Early ambulation is the primary goal to prevent complications associated with immobilization and to regain the patient’s ability to walk. 2 Surgical stabilization of comminuted fractures remains a challenge for all surgeons.

Many types of implants have been used that can be broadly categorized into 2 groups: extramedullary screw-plate devices and intramedullary nail devices. Dynamic hip screws or dynamic condylar screws with a long side plate are the most commonly used extramedullary screw-plate devices. However, for unstable fractures, intramedullary nail devices have more biomechanical advantages, including greater stability under weight-bearing, owing to a shorter lever arm, 3 and application by a minimally invasive surgical procedure that leads to less blood loss and fewer wound complications. 4-6

Use of a reconstruction nail or trochanteric nail for the treatment of complex proximal femoral fractures is the favorable method, 7,8 but associated complications, including iatrogenic femoral shaft fractures (3%-11%), lag screw cutout, and nail breakage (4%-8%), are problematic. 5-11 In 2004, a new trochanteric nail design—the proximal femoral nail antirotation (PFNA; Synthes, Paoli, Pennsylvania)—was developed. Some unique characteristics of the PFNA nail include the nail curvature (which better matches the anatomy of the femur), the material (a composite of titanium resulting in a flexible nail), and the single helical blade, all of which render it suitable for the treatment of comminuted proximal femoral fractures. 12,13

In the current study, we compared the radiographic and functional outcomes of comminuted proximal femoral fractures treated by the PFNA nail and the reconstruction nail (Recon; Zimmer, Warsaw, Indiana).

Materials and Methods



Between 2003 and 2010, 30 patients with AO/Orthopaedic Trauma Association (OTA) 31-A3 fractures combined with proximal 32 fractures underwent osteosynthesis of cephalomedullary nailing in our institution. Between March 2003 and February 2008, we used the Recon nail in 16 fractures. Between April 2008 and July 2010, we used the PFNA nail in 14 fractures. Of the 14 patients treated with the PFNA nail, 1 was excluded because the patient underwent PFNA nailing as the salvage procedure for previous implant failure. Of the 16 patients treated with the Recon nail, 10 were excluded because it was a revised surgery, due to pathologic fracture, or due to loss to follow-up before fracture union.

All 23 patients who followed-up consecutively until fracture union (a minimum follow-up period of 18 months) were reviewed retrospectively. Our Institutional Review Board approved this retrospective study. Follow-up evaluations were performed at 1, 3, 6, and 9 months and yearly thereafter. We clinically reviewed the age, gender, grade of the American Society of Anesthesiologists scale, injury severity score, reduction methods, operative time, blood loss, walking status 5 (4=able to walk independently; 3=able to walk with a single stick; 2=able to walk with a frame; 1=needs to be hoisted from bed to chair), and functional results (the assessment system of Friedman and Wyman) (Table 1). 14
Table 1: Friedman and Wyman 14 Classification of Functional Outcome

From radiographs that were obtained postoperatively in the operation room and at each follow-up visit, we analyzed the quality of reduction, position of the lag screws in the femoral head, change in the neck-shaft angle, and union time. The quality of reduction was graded as good, acceptable (5°-10° varus/valgus or anteversion/retroversion), or poor (>10° varus/valgus or anteversion/retroversion). 15 The position of the lag screw in the femoral head was assessed by dividing the femoral head into superior, central, and inferior on the anteropostior (AP) view and anterior, central, and posterior on the lateral view. A good position of the lag screw was defined as central or inferior on the AP view and central on the lateral view. 15 Fracture union was determined radiographically as the appearance of a bridging callus on 3 or 4 cortices in the AP and lateral views and clinically as a lack of pain sensation around the fracture site.

The complications were investigated perioperatively and postoperatively. Hip or thigh pain and the necessity of oral medications were recorded. Unplanned surgical management associated with the fracture treatment was recorded as major reoperation (revised nails and auto-bone grafting) or minor reoperation (removal of locking screw, wound debridement, and removal of hardware after union).

The surgical procedures were all performed by 2 experienced traumatologists (K.C.L., S.W.Y.). All patients were placed in the supine position. The injured leg was placed in mild adduction to facilitate nail insertion. Closed reduction by the traction boot was performed under image-intensified control. If closed reduction was not satisfactory, mini-open reduction was performed. Nail implantation was performed according to standard protocols for either the PFNA or Recon nails. The Recon nails were applied through the entry point at the piriformis fossa and were made of composite of stainless steel, and the lag screws were placed in a 2-screw configuration. The implanted PFNA nails were inserted through the entry point at the trochanteric tip and were made of composite of titanium alloy with 6° valgus bending, and the lag screws were placed in a one-helical-blade configuration. The femoral canal was over-reamed by 2 mm in the Recon nail group and under-reamed by 1 to 2 mm in the PFNA nail group. The diameters of the nails used were 10 and 11 mm for the Recon nails and 9, 10, and 11 mm for the PFNA nails. The nail was introduced via a long guide wire with a 130° aiming arm. After checking the length and alignment of the femur, static and dynamic distal locking screws were applied using the freehand technique (Figures 1, 2)



Figure 1: A 30-year-old woman with a comminuted proximal femoral fracture (A). Fixation with the PFNA nail (Synthes, Paoli, Pennsylvania) (B) and bone union 3 months later (C).

Figure 2: A 28-year-old woman with a comminuted proximal femoral fracture (A). Fixation with the Recon nail (Zimmer, Warsaw, Indiana) (B). After auto-bone grafting for nonunion 4 months after fixation, fracture union occurred at 1 year (C).

Continuous variables such as age, injury severity score, operation time, blood loss, amount of blood transfusion, change in neck shaft angle, and time to union were analyzed using the Student t test. The chi-square test or Fisher’s exact test, where appropriate, was used to compare categorical variables. The differences were considered to be statistically significance when P values were <.05.

Results

The PFNA nail group consisted of 8 men and 5 women (mean age, 53 years; range, 22-90 years), with an average follow-up duration of 20 months (range, 18-24 months). The Recon nail group consisted of 7 men and 3 women (mean age, 42 years; range, 18-74 years), with an average follow-up duration of 24 months (range, 18-32 months). The causes of fractures were related to high-energy trauma, including falls from high heights and motor vehicle accidents, in 10 fractures in the PFNA nail group and 8 fractures in the Recon nail group. Associated injuries included brain hemorrhage (PFNA nail group, n=2; Recon nail group, n=3), facial bone fractures (Recon nail group, n=4), lung contusion (PFNA nail group, n=1; Recon nail group, n=2), pelvic fractures (PFNA nail group, n=1; Recon nail group, n=2), upper extremity fractures (PFNA nail group, n=1; Recon nail group, n=4) and lower leg fractures (PFNA nail group, n=3; Recon nail group, n=4). The injury severity scores did not differ significantly statistically in the 2 groups (P=.087). On the American Society of Anesthesiologists scale, 4 patients were graded 1, five patients were graded 2, and 4 patients were graded 3 in the PFNA nail group, whereas 5 patients were graded 1, four patients were graded 2, and 1 patient was graded 3 in the Recon nail group. Open reduction was performed for 5 fractures in the PFNA nail group and 3 fractures in the Recon nail group. A longer operative time (P=.006) and more blood loss (P=.012) with more blood transfusions (P=.274) was observed in the Recon nail group than in the PFNA nail group (Table 2).

Table 2: Baseline and Perioperative Data

On postoperative radiographs, good or acceptable reduction was obtained in 11 patients in the PFNA nail group and 6 patients in the Recon nail group (P=.341). For the PFNA nail group, postoperative measures of the injured and uninjured femur showed an average neck-shaft angle of 131.1° and 135.8°, respectively. The average difference between the measured angles was 4.7° (range, 0°-15°). For the Recon nail group, postoperative measures of the injured and uninjured femur showed an average neck-shaft angle of 138.5° and 130.2°, respectively. The average difference between the measured angles was 8.8° (range, 0°-15°). The difference in the change in the neck-shaft angle between the 2 groups was statistically significant (P=.048). Two fractures in the PFNA nail group and 4 fractures in the Recon nail group met the criteria for varus malreduction.

Intraoperative complications included a broken drill bit (Recon nail group, n=1), a missed distal locking screw (PFNA nail group, n=1), and an iatrogenic femoral shaft fracture (Recon nail group, n=1). Postoperative complications included non-fatal pulmonary embolism (PFNA nail group, n=1), cerebrovascular accident (PFNA nail group, n=1), urinary tract infection (PFNA nail group, n=1; Recon nail group, n=1), and deep infection related to the initial proximal femoral open fracture (Recon nail group, n=1). In the PFNA nail group, end-cap dislodgment was noted in 1 patient at 4 months without tensor fascia irritation and the need for reoperation. In the Recon nail group, upper migration and protrusion into the hip joint of the proximal antirotation screw was noted in 1 patient. The protruding screw was removed 3 months later (Figure 3).


Figure 3: Complications of the Recon nail (Zimmer, Warsaw, Indiana). Lateralization of entry portal while reconstruction nailing with resultant varus malreduction and protrusion of antirotational screw into hip joint noted 2 months later (A) and malreduction with delayed union after reconstruction nailing (B). Complications of the PFNA nail (Synthes, Paoli, Pennsylvania). Secondary varus migration and end-cap dislodged observed 4 months later (C) and additional cerclage wiring with delayed union (D).

The average fracture union time was 21.5 weeks (range, 12-52 weeks) for the PFNA nail group and 31.8 weeks (range, 12-68 weeks) for the Recon nail group (P=.148). Two patients in the PFNA nail group and 4 patients in the Recon nail group encountered fracture delayed union or non-union (P=.341) (Figure 3). More patients in the Recon nail group compared with the PFNA nail group underwent major or minor reoperation (P=.012). Three patients in the Recon nail group underwent major re-operation owing to delayed or nonunion: 1 had revised nailing with auto-bone grafting and 2 had auto-bone grafting only. Minor reoperations included debridement (Recon nail group, n=1), dynamization (PFNA nail group, n=1), removal of a protruding locking screw (n=1 in the Recon nail group), and removal of hardware after fracture union (PFNA nail group, n=1; Recon nail group, n=3). Three cases of secondary varus migration and 1 case of hip/thigh pain (requiring oral medication for pain control) were observed respectively in the 2 groups. No implant failure (cut-out of the lag screw or nail breakage) occurred in either group. Comparing the number of the patients who regained their preinjury walking ability in the PFNA and Recon nail groups, no significant differences (P=.068) were observed. The functional results were acceptable and similar in the 2 groups (P=.497) (Table 3).


Table 3: Complications and Outcomes

Discussion

Comminuted proximal femoral fracture proximally involves the pertrochanteric region, including the basal neck, the piriformis fossa, the greater and lesser trochanter, and distally extends to the proximal middle third of the femoral shaft. In these complex fractures, implant selection has long been a matter of debate. Many conventional implants, including dynamic screw-plate devices and locked intramedullary nail devices, have been used, but the outcomes were not satisfactory. 8,10,11 Nonetheless, intramedullary nail devices have been proven to have more advantages than extramedullary screw-plate devices in unstable pertrochanteric fractures. Compared with extramedullary screw-plate devices, intramedullary nailing by limited invasive procedures that minimize soft-tissue dissection and preserve the hematoma, essential elements for fracture union, 16 reduces wound complications. 4,5

Mechanically, intramedullary nail devices have shorter lever arms that transmit the loading force more medially. 3 As a result, intramedullary nail devices provide a superior resistance to head collapse into the varus than extramedullary screw-plate devices. Furthermore, cephalomedullary nailing confers sufficient stability for early postoperative ambulation. Early mobilization reduces many postoperative complications, including pulmonary embolism, deep venous thrombosis, aspiration pneumonia, and pressure ulcers. Patients, particularly the elderly, tend to regain their walking ability following early rehabilitation courses. 2

Previously, the Recon nail was used to stabilize comminuted subtrochanter fractures. 9,11,17 Recently, many authors have concluded that the PFNA nail, a new trochanteric nail device, is a reliable internal fixator for the treatment of unstable pertrochanter fractures. 12,13 Some comparative studies, such as PFNA vs third-generation gamma nail 18 or PFNA vs proximal femoral nail, 19 have been performed, and all agreed the that the PFNA nail offered some benefits including fewer lag screw complications, less blood loss, a shorter fluoroscopy time, and a shorter operation time. However, we were unable to find any report in which the proximal femoral nail antirotation was compared with the Recon nail for the treatment of comminuted proximal femoral fractures (AO/OTA 31-A3+proximal 32).

One of the differences between the PFNA nail and the Recon nail is the entry point for nail placement. The ideal starting point for nailing in proximal femoral fractures is controversial. Moein et al 20 performed a cadaver study and concluded that nail entrance through the piriform fossa resulted in damage to the tendons of the gluteus minimus, piriformis, and obturator muscles and the superior gluteal nerve, leading to hip abduction weakness and injury to the medial femoral circum-flex artery, and penetration to the hip joint, leading to the risk of partial head necrosis and septic arthritis, respectively.

Identifying the piriformis fossa, the entry point of the Recon nail, is technically demanding. 11 The results of our study supported this point of view, with greater intraoperative blood loss and a longer operation time with Recon nailing via the piriformis fossa entry portal. However, Starr et al 21 found no difference between the 2 entry portals for cephalomedullary nails and suggested that the choice of starting point is probably best decided on the basis of the surgeon’s familiarity.

On evaluation of postoperative radiography, the smaller change in the neck-shaft angle between the injured and uninjured hip in the PFNA nail group was statistically significant. This finding demonstrated that the PFNA nail has a better realignment ability than the Recon nail because the PFNA nail had a 6° valgus bending, which matched the femoral canal curvature, and a larger proximal nail diameter, which acts as an indirect reduction tool, like a joystick, for the proximal fragment. Because the PFNA nail is a more flexible construct (composite of titanium) and has a fluted nail tip, the technique of nail reduction can be performed securely without concern regarding iatrogenic shaft fracture, especially over the medial cortex below the lesser trochanter.

Over-reaming of the shaft canal was suggested before the insertion of the Recon nail because the nail is composed of a composite of stainless steel. However, enlargement and lateralization of the entry portal from the piriformis fossa to the trochanteric tip after over-reaming were observed. This incorrect entry portal led to postoperative varus malalignment. For PFNA nailing, we allowed under-reaming of the shaft canal, which reduced the risk of lateralization of the entry portal and secondary displacement of bony fragments. Several authors have also reported that varus malalignment is common after cephalomedullary nailing through the piriformis fossa entry portal. 11,17

For control of the proximal part of the femur, no consensus has been reached with regards to the best way to anchor—using 1 or 2 traditional femoral neck screws or a single blade. The intramedullary nail with a 1-screw configuration has a weak point in terms of the rotational stability 15 ; however, the intramedullary nail with a 2-screw configuration leads to the Z-effect 22 (lateral migration of the neck screw and concomitant medial migration of the antirotational screw). The high incidence of femoral neck screw cutout using both the 1- and 2-screw configurations, particularly in osteoporotic or elderly patients, is still problematic. 23 Therefore, a single helical blade is an alternative design; this has been shown to have a higher resistance to head collapse than the traditional screw design in biomechanical studies. 24,25

As shown by our results, cephalomedullary nailing with a traditional screw or helical blade offered enough stability for weight bearing without implant failure. However, secondary varus migration was observed in both groups. The resistance to varus migration of the traditional screw and the blade was similar in our study. Saurav et al 5 concluded that, notwithstanding any cephalomedullary nailing, comminuted proximal femoral fractures still migrate into varus gradually without interfering with fracture union.

In our series, the most common late complications were delayed union or non-union, particularly over the proximal femoral shaft because of lesser vascularity than the trochanteric region. More fractures encountered union problems after Recon nailing, but no significant difference existed. Following a review of previous reports, direct injury that damaged the blood supply surrounding the fracture site, inadequate reduction, extensive open reduction with massive periosteal stripping, and fracture over-distraction by a static distal locking screw are the etiologies of delayed union or nonunion. 5,26 In our series, more fractures experienced varus malreduction in the Recon nail group, which interfered with the healing process and delayed the union time. Compared with previous reports, 11-13,17-19,21 the fracture union time was longer in the 2 groups in our series. This might be associated with the high-energy trauma mechanism of the majority of the fractures, which resulted in soft tissue damage and blood supply compromise. Dynamization is a method that can be attempted in delayed fracture healing of shaft fractures. However, especially in a comminuted fracture, it predisposed to bone shortness. 27 Cancellous bone grafting, exchanging the nail, and additional side-plating are all effective procedures that have been demonstrated in the previous literature. 28,29

Yaozeng et al 18 observed hip or thigh pain to be one of the most common complications after intramedullary nailing, without having a significant effect on postoperative function. Significant injuries to the muscles and tendons of the hip abductors and external rotators by nailing through the piriform fossa lead to soft tissue scarring and resultant proximal thigh pain. 20 The nail designs are also associated with implant pain. For the PFNA nail, the proximal 6° valgus bending curve matched the anatomy of the femur, and positioning of the distal interlocking screws more proximally prevented stress concentration around the nail tip and the composite of titanium reduced stress shielding. These characteristics prevented residual implant pain after fracture union. Comparing our results, more patients in the Recon nail group complained of implant irritation when exercising, particularly young patients, and underwent removal of the nails after fracture union.

The materials used in the construction of the PFNA and Recon nails are titanium alloy and 316L stainless steel, respectively. The modulus of elasticity of titanium alloy is approximately half that of 316L stainless steel and more closely approximates that of the cortical bone. In previous concepts, titanium intra-medullary nails exhibited increased strength, flexibility, and biocompatibility. 30 Although biomechanical testing revealed similar strengths and equivalent clinical results, 31 titanium intra-medullary nails with a more flexible construct still had some advantages, including simplifying the surgical procedure, preventing iatrogenic fractures, and lessening the implant pain in our series.

In other reports, restoration of preoperative mobility was obtained in approximately 50% to 80% of patients treated with Recon or PFNA nails. 12,13,18,19,21 In terms of regaining walking ability, our results in the 2 groups were better than those of previous studies. The key points related to clinical outcomes were age, comorbidity, fracture type, and surgeon’s experience, not the implant. 2 The results of our study demonstrated that, regardless of the nail construct, more than half of patients with proximal femoral fractures return to their preoperative walking status and obtain acceptable functional results at the time of fracture union.

Our study had some limitations. First, this was a retrospective study. Second, the case numbers were small in both groups because comminuted proximal femoral fracture is rare. Finally, surgery was performed by the 2 orthopedic surgeons (K.C.L., S.W.Y.) in our institution.

Conclusion

For the treatment of comminuted proximal femoral fractures, use of PFNA and Recon nails are both effective clinically; however, the PFNA nail provides a shorter operation time, less blood loss, and better realignment ability and reduces the incidence of reoperation. Therefore, the PFNA can be considered a better device than the Recon nail.

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