Comparison of percutaneous compression plating and short reconstruction nail for treatment of intertrochanteric fracture

Abstract

Objective:  To compare percutaneous compression plating (PCCP) with Trigen short reconstruction nail (Trigen SRN) for the treatment of intertrochanteric hip fracture.

Methods:  Eighty‐four patients with intertrochanteric hip fracture admitted to our hospital from January 2007 to June 2008 were included in this retrospective study. Thirty‐six patients were treated with PCCP and 48 with Trigen SRN. Information regarding age, surgical time, blood loss, length of follow‐up, mortality, fracture impaction, time to union, complications, Harris score and visual analog scale (VAS) were all recorded.

Results:  The mean follow‐up time was 16.3 ± 3.2 months (13–19 months). The mean time to achieve radiological fracture healing was 3.6 ± 0.8 and 4.1 ± 1.0 months for the PCCP and Trigen SRN groups, respectively (P= 0.020); the mean Harris hip scores were 78.1 ± 4.8 and 74.1 ± 5.2 (P= 0.001); and the mean fracture impaction was 3.6 ± 2.3 and 3.3 ± 2.6 mm (P= 0.023). There were no statistical differences between the two groups in duration of surgery (P= 0.131) and blood loss (P= 0.268). The amount of nail in the inferior‐central quadrants was greater in the PCCP group than in the Trigen SRN group.

Conclusion:  PCCP achieves earlier pain release and better fracture reduction than Trigen SRN.

Introduction

Osteoporotic hip fractures, one fourth of which are intertrochanteric fractures, are considered to be a “modern epidemic” as the population grows increasingly older ¹ . About 1.7 million new intertrochanteric fractures occur in the world every year, and the number is expected to have doubled by the year 2040 ² . Several methods for managing this kind of fracture are described in published articles, but which one is optimal remains controversial.

The percutaneous compression plate (PCCP) device was developed by Gotfried in the 1990s ³ , it can be inserted using a minimally invasive technique. It is a same‐diameter double‐screw construct with sliding capability that can theoretically facilitate rotational stability and provide controlled fracture impaction. The screw diameter is 7 mm, and the outer thread diameter is 9 mm. Some previous in vitro biomechanical studies have showed that double‐screw fixation has more cyclic loading, torsional rigidity and migration resistance than single‐screw devices ⁴ . Giancola et al. compared PCCP with Gamma nail for Arbeitsgemeinschaft fur Osteosynthesefragen‐classification/Orthopaedic Trauma Association (AO/)TA) 31A1 and A2 intertrochanteric hip fractures, and found that the PCCP group had less blood loss, fewer implant‐related complications and comparable surgery times ⁵ . Peyser et al. compared PCCP with dynamic hip screw (DHS) for the same type of fracture, and found that the PCCP group had a shorter surgery time, reduced need for blood transfusions and fewer complications ⁶ .

The Trigen short reconstruction nail (Trigen SRN) is another minimally invasive fixation method which is an improvement on the Gamma nail in that it has increased antirotation capacity ⁷ . It is also a same‐diameter double‐screw construct, is commonly used in China, and the results are reported to be good ⁸ . The screw diameter is 6.4 mm. It is different from another intramedullary fixation system called proximal femoral nail (PFN), which also has two neck screws, but the diameters of the two neck screws in PFN are different ⁹ .

Palm et al. suggested treating simple intertrochanteric factures (A1 to A2.1)with a sliding hip screw fixed to a side‐plate, and treating more complex intertrochanteric fractures (A2.2 to A3) with a sliding hip screw fixed to an intramedullary nail ¹⁰ . In order to investigate whether the extramedullary implant system with an additional screw is a better choice for AO/OTA 31A1 and A2 intertrochanteric fractures, we performed this retrospective study to evaluate the efficacy and possible advantages of PCCP versus the Trigen SRN. In addition, we thought that there are other important factors besides the double‐screw system that influence the surgical outcome, so our second objective was to ascertain what they were.

Materials and Methods

Patient's data

Eighty‐four patients with AO/OTA 31A1 and A2 intertrochanteric hip fractures admitted to our hospital from January 2007 to June 2008 were included in this retrospective study. No patients had severe coxarthrosis of the ipsilateral hip, multiple trauma and reversed or bifocal fractures, and all of them had unilateral hip fractures. There were 36 patients in the PCCP (Orthofix SRL, Verona, Italy) group and 48 in the Trigen SRN (Smith & Nephew, London, UK) group. The mean age was 72.8 ± 7.3 years in the PCCP and 76.6 ± 11.1 years in the Trigen SRN group. All patients were fully informed of the features of the two methods before surgery. The patients themselves selected the surgical method based on the surgeon's suggestions. All of them were informed that data concerning their case would be submitted for publication. Review of preoperative radiographs of the hips was undertaken to confirm the fracture pattern. This study was approved by the hospital ethics committee.

Surgical technique

The operative procedures of PCCP and SRN were performed as previously reported ⁸ , ¹¹ . Briefly, in the PCCP group, the patient was first X‐rayed to confirm fracture reduction. Then a 2.5 cm lateral incision was made and the plate inserted distally through it over the periosteum. A second 2.5 cm incision was made and the first cervical screw inserted, angled at 135°, followed by three bicortical diaphyseal screws and finally the second parallel cervical screw. During the operation, a posterior reduction device afforded the PCCP group a second chance at reduction and enabled achievement of better reduction.

In the SRN group, the patient was placed face up and fracture reduction, which was temporary fixed by pins, also confirmed by X‐ray. A 5 cm incision was made over the lateral trochanter, and deepened down to the trochanter. Next, a guide pin was inserted in the middle third of the lateral trochanter and guided by X‐ray to the distal medullar space. Then an extramedullary nail was inserted along the guide pin, followed by two neck screws and two distal lock screws.

Postoperative management and follow up

All patients received Fraxiparine (GlaxoSmithKline, Brentford, Middlesex, UK) post‐operatively to prevent deep‐vein thrombosis. Intravenous antibiotics were given once at the onset of surgery and tramadol hydrochloride administered by a pain pump was used to prevent postoperative pain. All patients started lower limb muscle exercises one day postoperatively, walked with a walking stick 2 weeks after surgery and were permitted free weight loading exercises 4 weeks after surgery.

Hospital charts and postoperative radiographs were reviewed for each study subject by two senior orthopedists. A data abstraction form was used to gather information regarding patient age, sex, mechanism of injury, number of days spent in hospital, length of surgery, and duration of follow‐up. All patients received outpatient follow‐up, including assessment of functional outcome and radiographic changes. Their morbidity, mortality, complications, Harris score (last follow up) and VAS score (first week, first month, third month, sixth month and twelfth month) were all recorded. Union of the fracture site was determined on a radiological basis, and the fracture healing time was also recorded. The radiological manifestations consisted mainly of blurring of the fracture line and continuous bony callus at the fracture site.

We used the method described by Tarantino to test the radiographic position of the inferior neck screw ¹² . It is thought that the position of the neck screw is closely related to the functional biomechanical outcome after the surgery, and the inferior‐central quadrants are considered to be more stable than the others. The position of the inferior neck screw was determined on the immediate postoperative radiographs using standard anterior‐posterior and lateral views. The radiographic variables evaluated included location of the inferior neck screw in the anterior‐posterior and lateral views, degree of fracture healing, neck shaft angle, cut out of the screw and mechanical failure of the device used.

Statistical analysis

Statistical analysis of data was performed using SPSS 16.0 software (SPSS, Chicago, IL, USA). The continuous variables of age, surgical time, blood loss, fracture impaction, time to union, Harris score and VAS were calculated and compared using Student's t‐tests. The results were considered to be significant at P < 0.05.

Results

The follow‐up time was 16.3 ± 3.2 months (range, 13–19 months). In the PCCP group, 32 patients underwent complete follow‐up (three patients were lost to follow‐up and one died). In the Trigen SRN group, 42 patients underwent complete follow‐up (one patient was lost to follow‐up and five died). None of the six deaths were caused directly by the fractures. Three patients died from coronary heart disease, one from cerebral infarction and two from traffic accidents. Of the four patients lost to follow‐up, one refused to continue follow‐up and three changed their addresses and phone numbers.

The clinical information and results of treatment for both groups are presented in Table 1. The locations of the interior sliding screw on radiograph in both groups are listed in Fig. 1, which shows that the amount of nail in the inferior‐central quadrants was greater in the PCCP than in the SRN group.

Table 1.

Patients' data and results of treatment in both groups

Group	Number of cases	Age (years)	Surgical time (minutes)	Blood loss (mL)	Time to union (months)	Harris Score	Fracture impaction	VAS
								1 week	1 month	3 months	6 months	1 year
Trigen	42	76.6 ± 11.1	59.5 ± 14.1	94.3 ± 24.0	4.1 ± 1.0	74.1 ± 5.2	3.3 ± 2.6	43.3 ± 6.6	24.5 ± 6.7	14.1 ± 4.4	11.3 ± 3.8	9.0 ± 3.3
PCCP	32	72.8 ± 7.3	64.8 ± 15.7	100.6 ± 24.5	3.6 ± 0.8	78.1 ± 4.8	3.6 ± 2.3	37.8 ± 7.4	20.0 ± 5.5	12.8 ± 3.5	9.9 ± 2.4	10.1 ± 2.9
t	—	2.493	2.330	0.630	5.645	11.545	5.132	11.143	9.639	2.101	3.177	1.868
P		0.123	0.131	0.430	0.020	0.001	0.023	0.001	0.003	0.150	0.079	0.176

Figure 1.

The location of the interior sliding screw on radiograph. The amount of nail in the inferior‐central quadrants was greater in the PCCP (15/32, 47%) than in the Trigen SRN group (14/42, 33%).

There was no delayed union, malunion, nonunion nor infection in either group, and no cases with a varus angle >15°after fracture healing. In the PCCP group, there was no lateral wall fracture during or after the operation. One case had slight upper neck screw migration 3months after surgery (Fig. 2). This migration was arrested by avoiding weight‐bearing until fracture healing had occurred. Also there were three cases of Brooker class I and three of Brooker class II ectopic ossification in the PCCP group. Additionally, there was an interesting case in the PCCP group where a bicortical diaphyseal screw breakage occurred 3 months postoperatively (Fig. 3). No screw breakage occurred in the Trigen SRN group but eight patients developed ectopic ossification cases, three being Brooker class I and five Brooker class II. There was one case with lateral wall fracture and three of femoral shaft fracture, of which two had no displacement and one underwent revision (Fig. 4).

Figure 2.

Radiographs of the right hip of a 57‐year‐old woman with AO/OTA 31A2 type intertrochanteric fracture stabilized by PCCP. (a) Preoperative X‐ray film, showing an AO/OTA 31A2 type intertrochanteric fracture; (b) X‐ray film 3 days postoperatively, showing the fracture has been reduced and fixed by PCCP; (c) X‐ray film 3 months postoperatively, showing a slightly displacement of the upper neck screw.

Figure 3.

Radiographs of the left hip of a 61‐year old man with AO/OTA 31A2 type intertrochanteric fracture stabilized by PCCP. (a) Preoperative X‐ray film, showing an AO/OTA 31A2 type intertrochanteric fracture; (b) X‐ray film 3 days postoperatively, showing the fracture has been reduced and fixed by PCCP; (c) X‐ray film 3 months postoperatively, showing bicortical diaphyseal screw breakage.

Figure 4.

Radiographs of the right hip of a 74‐year old woman with AO/OTA 31A1 type intertrochanteric fracture fixed by Trigen short reconstruction nail. (a) Preoperative X‐ray film, showing an AO/OTA 31A1 type intertrochanteric fracture; (b) X‐ray film 3 days postoperatively, showing the fracture has been reduced and fixed by Trigen short reconstruction nail; (c) X‐ray film 1.5 months postoperatively, showing a femoral fracture around the implant.

Discussion

Intertrochanteric hip fracture is very common in the elderly and has high morbidity and mortality. Besides this double‐screw system, there have been many single‐screw systems used for intertrochanteric hip fractures, such as the DHS and Gamma nail. A meta‐analysis has showed DHS to be the best choice for stable fractures including AO/OTA 31A1 and A2.1 because of its high performance‐price ratio, while for unstable AO/OTA 31A2.2 and A2.3 fractures, the treatment is still controversial ¹³ . What needs to be pointed out is that the complication rates of these single‐screw devices for intertrochanteric hip fractures are still high. DHS is sometimes disrupted by excessive sliding of the screw, and the Gamma nail is usually complicated by fracture of the femoral shaft ¹⁴ . Madsen et al. reported that secondary fracture displacement can be as high as 34% with DHS, 18% with the Gamma nail and 9% with DHS with a laterally mounted trochanteric stabilizing plate ¹⁵ . Stappaerts et al. mentioned that the rates of postoperative complete collapse or secondary displacement can be 26% ¹⁶ . However, both PCCP and Trigen SRN are double‐screw constructs with a sliding capability that can theoretically facilitate rotational stability and provide controlled fracture impaction. They also both involve minimally invasive fixation methods, which in theory make results in them producing less damage to surrounding soft tissues and fewer complications.

The stability of the two systems

There were no statistically significant differences between the two implants in operation duration and blood loss, whereas the PCCP group had higher VAS scores one week and one month after the surgery, which means the PCCP group achieved better early stability before fracture healing had occurred. As we know, the intramedullary nail is considered to be theoretically more stable because of its shorter force arm and torque; unfortunately this advantage was not confirmed by the comparison between Trigen SRN and PCCP in our study. There are three possible explanations for this.

Firstly, better reductions can be achieved in the PCCP group. Carr et al. have pointed out that good realignment of posterior and internal cortical bone can reduce the fracture redisplacement rate and prevent collapse ¹⁷ . The superior reduction in the PCCP group is due to the second reduction technique of the posterior reduction device, which can correct slight varus, valgus, intorsion or extorsion. However, the Trigen SRN does not offer a second chance at reduction and, in our experience, insertion of the intramedullary nail during the operation sometimes changes the position of the pin which is used for fixation of the reduction during surgery, resulting in movement of the fracture fragments.

Secondly, most of the inferior neck screw of PCCP was found to be located in the inferior‐central quadrants on lateral and frontal X‐ray images, whereas the percentage was much smaller in the Trigen SRN group. A biomechanical study of single sliding lag screw for unstable intertrochanteric hip fracture showed that the best position for the main screw is in the middle on the lateral view and in the inferior quadrants on the frontal view ¹⁸ . Hsueh et al. have also suggested placing the lag screw in the middle/middle or inferior/middle position on the basis of evaluation of 937 patients with single sliding lag screw ¹⁹ . Though no similar studies of double‐screw systems have been reported, we believe the conclusion reached for the single screw system can also be applied in double‐screw systems, and that the inferior‐central position of the inferior neck screw results in better stability of the femoral neck.

Thirdly, the diameter of the screws in PCCP was larger than in Trigen SRN. The first screw in surgery is prone to be inserted closer to the calcar femorale because of the limited space in the femoral neck, and this directly contributes to the location of the inferior screw in the inferior‐central quadrants. Biomechanical study has also confirmed that a larger diameter screw through the femoral neck and located in the head has better stability ²⁰ . Finally, the PCCP is made of tension‐free steel, while the Trigen SRN is made of titanium. The advantage of tension‐free steel in regard to its elastic modulus can result in superior stability before fracture healing than that conferred by titanium.

Complications

Breakage of bicortical diaphyseal screw

It was interesting to find a case in our PCCP group with breakage of the first bicortical diaphyseal screw (Fig. 3). The exact mechanism of this complication is unknown; there are two possible explanations. One is that the vertical force coming along the femoral shaft breaks the screw, and the other is that the femoral neck puts an oblique force on the lateral plate, at an angle of 135°, resulting in eversion of the lateral plate. This eversion force is so strong that it directly breaks the first bicortical diaphyseal screw. Its importance should be explored by further biomechanical studies.

Fracture of the lateral wall

It has been reported that fracture of the lateral wall usually occurs in intertrochanteric fractures treated with DHS, and the location of the fracture is always at the site of the hole drilled for the screw ²¹ . The large diameter of the screw is considered to be the main reason. More and more studies have shown that an integral lateral wall is one of the key factors influencing the outcome ¹⁰ , ²¹ , ²² , in addition to the medial calcar femorale. In our study, even though the 9.3mm‐diameter of the external screw countersunk in PCCP creates more destruction of the lateral wall than the 6.4mm‐diameter screw used in Trigen SRN, there were no lateral wall fractures in our PCCP clinical group and only one such case in the Trigen SRN group. This shows that the designs of PCCP and SRN both dramatically reduce the risk of lateral wall fracture, compared with DHS. An integral lateral wall offers strong support to the fracture site, which results in a stable environment for fracture healing. This probably explains the better results of both PCCP and SRN compared to DHS.

Compression of the fracture site

In our study, the tested fracture impactions of the two groups were not obvious; both were lower than the mean 5–6.5 mm for DHS reported in several articles ²³ , ²⁴ . This may be explained by two main factors. One is that double‐screw system can provide better stability for the reduction, and the compression force at the fracture side is more uniformly distributed than with the single‐screw system. The other is that the diameter of a single screw is smaller in the double‐screw system and the sliding force of a single screw is, of course, also smaller. So it is not strange to find less screw sliding with the double‐screw system than with DHS. Additionally, in the SRN group, the intramedullary nail itself plays a role in preventing movement of the fracture fragments, the small titanium screws have strong bending strain under weight‐loading conditions and this bending strain directly prevents sliding impaction.

Cut‐out or migration of the screw

Cut‐out of the screw is reported to be the main failure complication in DHS, and this is mainly related to the tip‐apex distance (TAD) of the screw. Hsueh et al. suggested the TAD should be kept to be less than 15 mm in order to avoid cut‐out of the sliding screw when treating intertrochanteric fractures with DHS ¹⁹ . In our study, we did not use the TAD index because the TAD is designed for the single‐screw system and cannot simply be used in a double‐screw system such as DHS. In our study, there was only one case in the PCCP group with slight migration. This can be explained by the local stability of the fracture side in the double‐screw system. Also it would be an interesting task to determine a useful index like the TAD for predicting the cut‐out rate of the double‐screw system, which would require a larger number of cases and further study.

Femoral shaft fracture

Since the application of intramedullary internal fixation in intertrochanteric hip fractures, femoral shaft fracture is a problem that has disturbed numerous orthopedic surgeons and patients. Luckily, the rate of femoral shaft fracture is decreasing with improvement in internal fixation devices and techniques ²⁵ . In our study, three fractures occurred in the Trigen SRN group, one of which underwent revision, but none in the PCCP group, which is in accordance with previous comparisons of extramedullary and intramedullary fixation systems. This implies that the design of the SRN still needs further improvement.

Limitations

This is a retrospective clinical study, and there may be unavoidable selection bias in the patient group. Also, the number of cases in our study is limited. We need more cases and further studies to confirm our results. But as we know, SRN is the only intramedullary same‐diameter double‐screw system nowadays, and we think that comparison between SRN and PCCP can enable us to achieve a better understanding of the design of the internal instrument as well as of intertrochanteric fracture itself.

Conclusion

This study shows that PCCP can achieve better reduction and good internal fixation in real time practice. It can result in earlier pain relief and has obvious advantages in treating AO/OTA 31A1 and A2 fractures. The design of the intramedullary nail of SRN needs further improvement because of the incidence of femoral shaft fracture. Though the same‐diameter double‐screw system has comparatively lower compression ability, they all achieve good clinical results. This implies that local stability may play a more important role than sliding compression at the fracture site.

Disclosure

No benefits of any type have been, or will be, received from a commercial party related directly or indirectly to the subject of this manuscript.