Mid-term outcomes after intramedullary fixation of peritrochanteric femoral fractures using the new proximal femoral nail antirotation (PFNA)

Materials and methods 

Between April 2006 and March 2008, 169 patients with peritrochanteric femoral fractures who were treated at the Affiliated Hospital to Nantong University were enrolled in this study. This group was a subset of a consecutive series of 201 peritrochanteric femoral fractures treated by the authors, of which 27 were stabilised by the dynamic hip screw (DHS) and five were treated non-operatively. Indications for the PFNA stabilisation included AO/OTA 31A fractures, AO/OTA 31A combined with 32 fractures and separate proximal 32 fractures. Of the 169 fractures stabilised with PFNA, 18 were lost to follow-up. Eight patients died within 12 months because of different causes, which were unrelated to the implant. The remaining 143 patients made up the study group.

There were 70 men and 73 women. As many as 75 injuries involved the left side, and 68 involved the right side. The mean age of the patients was 67 years (range, 20–93 years). A total of 101 injuries were caused by a fall from a height; 23 by a fall from a greater height; and 19 by a motor-vehicle accident. As many as 21 patients sustained at least one additional injury; these associated injuries included two pelvic fractures, five closed head injuries, nine chest injuries and 12 other injuries involving an upper extremity.

According to the OTA classification system,9 fractures were classified as 19 cases of AO/OTA 31A1 fracture, 83 cases of 31A2 fracture, 28 cases of 31A3 fracture, eight cases of 31A combined with 32 fracture and five cases of separate proximal 32 fracture. A1 fractures are simple, two-part fractures, whereas A2 fractures have multiple fragments. A3 fractures include reversed oblique and transverse fracture patterns. The distinctive characteristic of A3 fractures is a fracture line that extends through the lateral femoral cortex distal to the vastus ridge of the great trochanter.27 With regard to co-morbidities, according to the American Society of Anesthesiologists (ASA) scale, 56 patients were classified as ASA 1, 61 patients were classified as ASA 2 and 26 patients were classified as ASA 3.4

All patients were evaluated preoperatively with use of two standard plain radiographs, an anterior–posterior radiograph and a medial–lateral radiograph. The operative time, the overall fluoroscopy time, the duration of hospitalisation and the surgical complications were recorded. The overall time from injury to surgery averaged 3 days (range, 1–11 days). Prophylactic antibiotic treatment was not used preoperatively and intra-operatively. Surgical treatment was performed as soon as the patient's general medical condition allowed. The intra-operative time was recorded from the time that the close reduction was started to the time that the wound was sutured closed.

Surgical techniques 

The patient was positioned supine on an extension table. The unaffected leg was abducted as far as possible and placed on a leg support, so that it allowed free fluoroscopic examinations. Adducting the affected leg by 10–15° favours the access to the medullary cavity. Closed reduction was performed under image intensifier control. In the majority of these cases, good reduction could be obtained by both adducting and internally rotating the affected leg under traction. Once the result was satisfactory, a 5-cm incision was made approximately 5-cm proximal from the tip of the greater trochanter.

The correct entry point and angle were essential for a successful result. The guide wire should be inserted on the tip or slightly laterally of the greater trochanter at an angle of 6° to the intended extension of the medullary. Occasionally, this procedure was rather difficult when there was a ‘floating’ greater trochanter or the reduction could only be maintained with the affected leg abducted. The femur was opened by power tool at high speed or carefully by hand. To prevent dislocating the fracture fragments, lateral movements or excessive compression forces were avoided. After mounting the nail on the radiolucent insertion device, the nail could be introduced manually into the femoral shaft. It was not a problem when there was a fracture line at the entry point, but sometimes the fracture fragments dislocated after nail insertion, mainly due to the incorrect entry point. Via the aiming arm, the guide wire for the PFNA blade was introduced into the femoral neck in such a way that the PFNA blade would be placed into the lower half of the neck on the AP view and centrally on a lateral view. Care should be taken to avoid the fracture line on the lateral aspect of subtrochanteric area during the guide wire insertion. Unlike the insertion of the hip screws of PFN, the PFNA blade was inserted by hammering. Simmermacher et al.30 did not think reaming of the femoral neck was necessary in osteoporotic bone. Nevertheless, we advise to ream the femoral neck in every case, otherwise dissociation of the fragments may occur during the helical blade insertion (Fig. 1). After reaming of the femoral neck, the guide wire for the helical blade was sometimes pulled out along with the reamer. It was necessary to reassure the position of the reinserted guide wire under image intensifier (Fig. 2). Distal interlocking via the aiming arm was achieved in 125 cases. The long PFNA was used in the other 18 cases. Distal interlocking in these cases was performed under image intensifier control.

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Fig. 1. A 72-year-old patient sustained a type 31A2 fracture. The PFNA blade was inserted without reaming of the femoral neck. (a) Insertion of the guide wire for the PFNA blade. Note the fracture was anatomically reduced. (b) The PFNA blade had been inserted into the femoral head and caused dissociation of the fragments.

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Fig. 2. The PFNA blade missed the reamed canal in the femoral neck during surgery. (a) Acceptable guide wire position in both views. (b) The guide wire was pulled out along with the reamer during surgery. The position of the reinserted guide wire had not been checked under image intensifier and the PFNA blade was placed in the wrong position which was anterior to the reamed canal. The arrow points to the reamed canal in the femoral head. (c) Unlocked the helical blade and removed it. Reinserted the guide wire and checked its position. (d) Final result.

Postoperative treatment and evaluation 

Altogether 66 patients with good bone quality, including 19 patients with stable trochanteric fractures and 47 patients with unstable fractures but who obtained good reduction and ideal implant position, were encouraged to begin with immediate full weight bearing as tolerated. The rest were allowed partial weight bearing. Actually, immediate full weight bearing was achieved in only three patients. Most patients started partial weight bearing 7–10 days postoperatively. Antibiotic treatment was used postoperatively for 3–5 days. No prophylaxis against deep vein thrombosis was given. Before each patient was discharged from the hospital, radiographs of the affected hip were made in the anterior–posterior and medial–lateral planes to assess fracture reduction. The quality of fracture reduction was graded as good, acceptable (5–10° varus/valgus and/or anteversion/retroversion) or poor (>10° varus/valgus and/or anteversion/retroversion).33 The position of the PFNA blade was graded as good if it was placed into the lower half of the neck on the AP view and centrally on a lateral view.

A follow-up evaluation, which included a clinical and radiographic assessment, was performed at 6, 13, 26 and 52 weeks. Patients were followed for a mean of 21 months (range, 12–36 months). The clinical results were assessed with the Harris hip score.17 The Harris hip score was categorised as excellent (90–100 points), good (80–89 points), fair (70–79 points) or poor (≤69 points). Radiographs of the affected hip were made in the anterior–posterior and medial–lateral planes at each follow-up visit, and any changes in the position of the implant and the extent of fracture union were noted. Fractures were judged to be healed radiographically if bridging callus was evident on three of four cortices as seen on two views.15

Results 

Fifteen patients (10%) required open reduction (Table 1). As many as 21 cases were thought to be difficult including seven cases of type 31A2, seven cases of 31A3, one case of proximal 32 and six cases of 31A combined with 32 fracture.

Table 1. Operative difficulties, complications and radiological evaluation in relation with fracture type.

		Type 31A1 (n=19)
	Operative difficulties		0
	Complications (1 case)	Deep venous thrombosis	1
	Radiological evaluation
	Reduction
	Good		19
	Acceptable		0
	Poor		0
	Implant position
	Good		19
	Poor		0

		Type 31A2 (n=83)
	Operative difficulties (7 Cases)	Difficult to unlock the fracture to correct translation and rotation	4
		Displaced fracture of the greater trochanter	2
		Sub-optimal reduction, especially in the lateral view, caused difficulty in positioning the PFNA blade	1
	Complications (7 cases)	Hematoma	3
		Urinary infection	2
		Pulmonary infection	1
		Deep venous thrombosis	1
	Radiological evaluation
	Reduction
	Good		70
	Acceptable		9
	Poor		4
	Implant position
	Good		78
	Poor		5

		Type 31A3 (n=28)
	Operative difficulties (7 cases)	Difficult to maintain reduction during nail insertion	2
		Difficult to unlock the fracture to correct translation and rotation	3
		End cap insertion	2
	Complications (3 cases)	Urinary infection	1
		Pulmonary infection	1
		Non-union	1
	Radiological evaluation
	Reduction
	Good		19
	Acceptable		6
	Poor		3
	Implant position
	Good		26
	Poor		2

		Proximal 32 and combination type (n=13)
	Operative difficulties (7 cases)	Reduction	4
		Nail insertion	1
		PFNA blade insertion	1
		Distal locking	1
	Complications (1case)	Delayed wound healing	1
	Radiological evaluation
	Reduction
	Good		6
	Acceptable		5
	Poor		2
	Implant position
	Good		9
	Poor		4

The mean duration of surgery was 72min with a range between 45 and 170min. The mean fluoroscopy time was 164s with a range between 92 and 396s. The mean time of hospital stay was 15 days. Postoperative X-rays showed a good or acceptable reduction in 134 cases (94%), and an ideal implant position in 131 cases (92%). All patients, except one, healed their fractures without any implant-specific complication (bending, breaking of the implant, cut out of the PFNA blade, femoral head penetration of the blade or ipsilateral fractures of the femoral shaft at the tip of the implant).

A 76-year-old patient sustained a type 31A3 fracture, which eventually failed to heal. A lateral protrusion of the blade was observed in the radiographs taken at the latest follow-up (Fig. 3).

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Fig. 3. Non-union of a 76-year-old female patient with a type 31A3 fracture. (a) Before operation. (b) Radiographs 7 days postoperatively demonstrating the big gap in the lateral aspect of the proximal femur was filled with bone substitute. (c) Radiographs 2 months postoperatively demonstrating absorption of the bone substitute. Callus formation was observed in the lateral view. (d) Ten months passed, the patient failed to heal the fracture. (e) Radiographs 32 months postoperatively demonstrating lateral protrusion of the helical blade.

The average time to bone healing was 16 weeks (range, 12–25 weeks). There were 12 (8%) postoperative complications including haematoma (three), urinary infection (three), pulmonary infection (two), deep venous thrombosis (two), delayed wound healing (one) and non-union (one). The perioperative data in relation to fracture type are shown in Table 2. Implants were removed in 19 patients after bony healing. This procedure was quite simple and less invasive.

Table 2. Perioperative data in relation to fracture type.

		Fracture type (AO classification)
		A1 (n=19)	A2 (n=83)	A3 (n=28)	Proximal 32 and combined type (n=13)	Total (n=143)
	Age (year)	70±17	72±14	61±17	43±16	67±17
	Duration to surgery (day)	3±1	3±1	3±1	4±3	3±1
	ASA score
	1	7	23	14	12	56
	2	5	48	7	1	61
	3	7	15	4	0	26
	Operative time (min)	63±10	68±11	80±12	100±25	72±16
	Fluoroscopy time (min)	131±30	148±54	186±61	265±93	164±67
	TAD (mm)	9±2	9±2	9±2	8±2	9±2
	Duration of hospitalisation (day)	15±2	15±2	14±2	16±3	15±2
	Time to bone healing (week)	15±2	16±2	16±2	20±3	16±2
	Follow up (month)	22±7	20±7	21±7	23±7	21±7
	Harris hip score (point)	84±11	83±10	84±10	86±7	84±10

At the time of the latest follow-up, 106 patients (74%) restored their preoperative mobility. The Harris hip scores results were as follows: 43 excellent, 63 good, 27 fair and 10 poor. A total of 106 patients (74%) had an excellent or good outcome. The mean Harris hip score was 84 points (range, 46–100 points). According to the patients and/or their caregivers, outcome was described as satisfactory in 84% of the patients.

A total of 40 patients were more than 80 years old. The mean duration of surgery was 68min with a range between 55 and 100min. The fixation was adequate to maintain reduction over time in all these cases. All the patients healed their fractures. The mean Harris hip score was 75 points (range, 46–92 points). Although only 17 patients had excellent or good outcomes, 36 patients (90%) were satisfied with the final results.

Discussion 

There has long been a debate concerning the preferred implant for stabilisation of peritrochanteric femoral fractures. Two broad categories of internal fixation devices are commonly used for peritrochanteric femoral fractures: sliding compression hip screws with side plate assemblies and intramedullary fixation devices. Sliding hip screws are the most commonly used devices. However, many authors have commented on the unsatisfactory results associated with the use of a sliding hip screw for fixation of the fractures.6, 9, 12, 14, 18, 20, 28, 31, 33 From a biomechanical point of view, an intramedullary device inserted via a semi-closed procedure is to be preferred, especially in elderly patients. However, the previously used intramedullary device, the Gamma nail, is technically demanding and not forgiving with high rates of fractures of femoral shaft.5, 17, 22, 25 Saarenpää et al.26 compared the functional results between the dynamic hip screw and the Gamma nail in the treatment of trochanteric hip fractures in a matched-pair study of 268 cases. More interestingly, they found a better walking ability and a lower mortality rate in the DHS group. The PFN has been developed as an alternative to the Gamma nail. A number of published reports of the PFN are satisfying. But problems are far from over.2, 3, 29 Recently published investigations support the superiority of the sliding hip screw over the previously used intramedullary nails in view of the lower complication rate.10, 19, 23 The newly designed PFNA features a helical blade. Biomechanical tests in cadaveric femurs have shown that this new fixation with a helical blade is superior to fixation with a standard sliding screw.32 The stable type 31A1 fractures were excluded in the majority of the literatures concerning the intramedullary devices for stabilisation of trochanteric femoral fractures, since it is generally accepted that excellent results can be achieved after the DHS application. However, 19 cases of this kind of fractures were included in this study. Not a single procedure was thought to be difficult. The average operative time was 63min (range, 45–80min). Anatomic reduction as well as ideal implant position was easily obtained in all cases. We found the PFNA was less invasive, safe and user-friendly, especially in the treatment of type 31A1 fractures.

To our knowledge, only one published paper,30 a multicentre study, reported the early results associated with the PFNA application in the treatment 315 cases of AO type 31A2 and 31A3 fractures. In this article, Simmermacher et al. reported 46 implant-related complications and 28 re-operations. In the present study, all 143 cases were performed in one department. There were 111 cases of AO type 31A2 and 31A3 fractures. Implant-related complication was not found in any case and we had no re-operations. The results compared favourably to not only Simmermacher's report but also most reports concerning the previously used intramedullary devices. Although intramedullary fixation devices have the advantage of immediate full weight bearing, we took a more conservative rehabilitation programme. Good bone quality anatomic reduction and ideal position of the helical blade were prerequisite for immediate postoperative full weight bearing in this study. In practical terms, most patients could only accept immediate active range of motion of the hip. The low incidence of implant-related complications might be partially attributed to our conservative rehabilitation programme, in which full weight bearing was delayed. A recent meta-analysis of 24 studies involving 3279 fractures found a slightly higher incidence of re-operations due to technical problems compared with extramedullary fixation techniques.19 In this study, all the authors were familiar with the PFN application before the advent of the PFNA. The low incidence of re-operations could be explained by the experienced surgical team.

Only one patient failed to heal her fracture. The patient suffered from diabetes mellitus, hypertension and coronary heart disease before the accident. She was the one of our first 30 patients treated with the PFNA, and also the only one who underwent primary bone grafting. The radiographs 10 months postoperatively demonstrated non-union of the fracture but the patient's relatives refused any further treatment for the fracture because of hemiplegia. The non-union as well as the lateral protrusion of the PFNA blade was mainly due to the inappropriate entry point for the PFNA blade, which caused rotational displacement and also a big gap in the lateral aspect of the proximal femur. Diabetes mellitus and lack of experience might also account for the failure.

There were 13 cases of 31A combined with proximal 32 fracture or separate proximal 32 fracture, all due to high-energy injury. Comminuted subtrochanteric femoral fracture as well as intertrochanteric fracture combined with comminuted femoral shaft fracture can be extremely difficult. Often, a limited open reduction is necessary. In case of an isolated large medial fragment in the subtrochanteric area, a cerclage was recommended. Relative stable fixation of a fracture of combination type by the long PFNA resulted in union through callus formation (Fig. 4).

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Fig. 4. Radiographs demonstrating the healing process of a 20-year-old patient with a 31A3 combined with 32C3 fracture. (a) Before operation. (b) Seven days postoperatively. Note the isolate large medial fragment in the subtrochanteric area was fixed by a cerclage. (c) Radiographs 5 months postoperatively demonstrating callus formation. (d) Radiographs at 2-year follow-up showing bony consolidation.

The PFNA is characterised by its rotational and angular stability with one single element, and it has been biomechanically proven to have a better purchase in osteoporotic bone.24 This was supported by the fact that satisfactory mid-term outcomes had been achieved in 40 elderly patients, who were more than 80 years old. Implants were removed in 19 relatively young patients, all after bony consolidation. Three patients asked to remove the implant due to the pain in the lateral aspect of the affected thigh, and one due to the limited range of motion of the hip. The hip function did not improve after implant removal, and only one of the three patients obtained pain-relief. The remaining 15 cases were affected by the thought that there was a foreign substance in the body and firmly asked to remove it. The procedure was quite simple and less invasive.

In conclusion, the PFNA is very effective in the treatment of various kinds of peritrochanteric femoral fractures. We feel that the newly designed device is safe and user-friendly. Nonetheless, it is technically demanding, otherwise obstacles and complications will ensue. The PFNA is a powerful aid for orthopaedic surgeons. We firmly believe favourable results can be achieved when this device is combined with skilful techniques as well as appropriate postoperative treatment.

Conflict of interest 

The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.