A comparative study of proximal femoral nail versus dynamic hip sliding plate and screw system for treatment of intertrochanteric hip fractures

 

 

Abstract               Background: Fracture of intertrochanteric femur has been recognised as a major challenge by the Orthopaedic community, not solely for achieving fracture union, but for restoration of optimal function in shortest possible time with minimal complications. Operative treatment in the form of internal fixation permits early rehabilitation and offers the best chance of functional recovery hence becomes the treatment of choice for virtually all fractures of trochanteric region. Among the various types of implant available i.e. fixed nail plate device, sliding screw plate and intramedullary devices, the compression hip screw is most commonly used but recent technique of closed intramedullary nailing is gaining popularity. The present study is to compare the results of Proximal femoral nailing (PFN) and Dynamic hip screw (DHS) in terms of effectiveness, strength of construct, early mobilisation of patients and their advantages / disadvantages when used to treat similar type of fractures. Material and methods: This prospective study was done at Government Medical college, Aurangabad between 2013-2016 under the guidance of its ethical committee. This study was conducted on 60 patients (30 patients were in PFN group and 30 patients were in DHS group). Clinical and radiological follow up of all patients were carried out regularly till the patients achieved maximum possible functions of injured limb. Results were evaluated using Harris hip scoring system. Results: Mean blood loss was 107ml. for PFN and 262ml. for DHS. Average surgical time was 79 minutes for PFN and 103 minutes for DHS. Average time of union was 12 weeks for PFN and 14.85 weeks in DHS. Conclusion: PFN has lesser operative time, lesser blood loss, early post-operative rehabilitation and better functional outcome especially in unstable fractures compared to DHS.

Key Word: Proximal femoral nail, Dynamic hip screw, Intertrochanteric femoral fractures.

 

 

INTRODUCTION

Intertrochanteric fractures are extra-capsular fractures extending from base of greater trochanter along intertrochanteric line to lesser trochanter just above medullary canal. Intertrochanteric fractures of femur are most commonly operated fractures. Intertrochanteric fractures are common in elderly people. The frequency of these fractures has increased primarily due to increased life span along with sedentary life due to urbanization. Trochanteric fractures when occur in younger population is due to high velocity trauma, whereas in elderly population it is mostly due to trivial trauma. Also, the geriatric age group (higher proportion in women) has a higher incidence of osteoporosis along with low energy falls from standing height accounts for approximately 90% of hip fractures in community. Higher velocity traumatic intertrochanteric fractures are relatively rare and are more common in men less than 40 years of age.¹ Intertrochanteric fractures can be managed by conservative or operative methods. Conservative methods were the treatment of choice until 1960 when Horowitz² documented that the mortality rates in conservative methods were higher as compared to operative methods. The trochanteric fractures managed by conservative methods usually unite. If suitable precautions are not taken than fracture undergoes malunion, leading to varus and external rotation deformity at the fracture site and shortening and limitation of hip movement.² As conservative methods resulted in higher mortality rates and complications like decubitus ulcer, urinary tract infections, pneumonia, thromboembolic complications, these methods have been abandoned.

Conservative methods are now indicated only under 2 conditions,

1. Elderly person with high medical risk for anaesthesia and surgery
2. Non ambulatory patient with minimal discomfort following injury.

Since this fracture is more common in the elderly patients, the aim of treatment should be prevention of malunion, and early mobilization. Taking all the factors into consideration, surgery by internal fixation of the fracture is an ideal choice.³ Factors determining the strength of fracture implant assembly depends on the bone quality, fragment geometry, fracture reduction, implant type and implant placement.⁴ Surgeon can control only the quality of reduction, choice of implant and its placement. As intertrochanteric fractures have the highest post-operative fatality rate among surgically treated fractures, they have become an important health issue and is very important to study and compare different surgical options available for these fractures.

Implants for the fixation of intertrochanteric fractures can broadly be divided into

1. Extramedullary devices, example: D.H.S
2. Intramedullary devices, example: P.F.N.

The most commonly used device is the Dynamic Hip Screw with Side Plate (D.H.S). This is a collapsible fixation device, which permits the proximal fragment to collapse or settle on the fixation device, seeking its own position of stability. The latest implant for management of intertrochanteric fracture is P.F.N (Proximal Femoral Nail). This implant is a cephalo-medullary device and has many potential advantages like⁵

1. Being intramedullary, load transfer is more efficient.
2. Shorter lever arm results in less transfer of stress and less implant failures
3. Advantage of controlled impaction is maintained.
4. Sliding is limited by intramedullary location, so less shortening and deformity.
5. Shorter operative time, less soft tissue dissection and less blood loss.

In view of these conditions, this study is taken up to compare the results of D.H.S and P.F.N.

MATERIAL AND METHODS

This was a prospective, analytical study aimed to achieve fracture union by using two different kind of internal fixation modalities in similar type of fractures.

Inclusion criteria: includes recent traumatic history, isolated intertrochanteric fractures, stable and unstable fractures and the consent to participate in study.

 Exclusion criteria: includes patients with multiple fractures, pathological fractures, old neglected fractures, paediatric age group, reverse intertrochanteric fractures and elderly patients with high medical risk for anaesthesia and surgery.

IMPLANT DETAILS:

Dynamic hip screw Components: The implant consists of a lag screw, a compression screw and a barrel side plate attached to it. Lag Screw is available in lengths from 60-110mm.Compression Screw of 36 mm is used which allows compression at the fracture site. Barrel side plate are available in angles of 125⁰,130⁰, 135⁰, 140⁰and from 4-12 holes. 135⁰ and 140⁰ plates are more often used. 4.5 mm cortical screws are used to fix the side plate with shaft. In our study we used lag screw of 60-110 mm and a side plate that allowed a purchase of at least 8 cortices with shaft of femur and 130-140⁰ angled plate depending upon the neck shaft angle determined pre-operatively.

Figure 1:

1 - Compression screw 2 - Richard’s screw 3 - Barrel plate

 

Figure 2:

1 - T Handle 2 - Angle guide 3 - Tap 4 - Guide wire

 

Figure 3:

1 - Screw driver for Richard’s screw 2 - Triple reamer

 

PROXIMAL FEMORAL NAIL

Components: The implant consists of a Proximal Femoral Nail, a self-tapping de-rotation 6.5mm screw, a self-tapping 8mm femoral neck lag screw, 4.9mm distal locking screws and an end cap. PFN is made up of either 316L stainless steel or titanium alloy. PFN comes in following sizes: Length of standard PFN is 250 mm and available length of Long PFN is 340, 360, 380, 400 and 420 mm.

Diameter: 9, 10, 11, 12 mm

Neck shaft angle range: 130⁰, 135⁰ The nail is having 14 mm proximal diameter. This increases the stability of the implant. There is 6⁰ medio-lateral valgus angle which prevents varus collapse of fracture, even when there is medial communition. The distal diameter is tapered to 9-12 mm, which also has a groove to prevent stress concentration at the end of the nail and avoids fracture of the shaft distal to the nail. Proximally it has two holes, the distal one for insertion of 8mm neck screw which acts as a sliding screw and the proximal one is for 6.5mm hip screw which helps to prevent the rotation. Distally the nail has two holes for insertion of 4.9mm locking screws of which one is static and the other one is dynamic hole which allows dynamization. In our study we used the standard length PFN of 250mm with distal diameter of 9, 10 and 11mm. The common neck shaft angle used was 135⁰ followed by 130⁰. End cap was not used.

Figure 4:

1 - Cannulated awl 2 - Proximal reamer 3 - T-handle

 

Figure 5:

1 - Proximal femoral nail with 14mm diameter with 6⁰medio-lateral valgus and tapered tip.

2 - 6.5mm de-rotation screw.

3 - 8mm lag screw.

4 - 4.9mm locking bolt in static mode 5 - 4.9mm locking both in dynamic mode

Figure 6:

1. Hammer assembly 2. Zig

 

Figure 7:

1 - Solapur protection sleeve

2 and 3 - Sleeve for guide wire and reamer for proximal screw

4 - Reamer for 6.5 mm de-rotation screw

5 - Reamer for 8mm lag screw

Pre-operative routine investigations were done.  Informed consent was obtained by patient for both surgical procedure and  participation in the study. After anaesthetic fitness all cases were operated under combined spinal and epidural anaesthesia on fracture table using standard protocol. Post-operative antero-posterior and lateral view x-rays of the operated hip were taken. Post-operatively static exercise in bed for glutei, hamstrings, quadriceps and breathing exercises were started next day of surgery. Sitting was allowed on next day of surgery with passive exercises in bed. Drain if inserted was removed after 48 hours. ROM exercises were started actively. The protocol for weight bearing, in stable fractures is to start partial weight bearing next day after surgery and full weight bearing was started after 6 weeks, while in unstable fractures, non-weight bearing walking was allowed on operated side with the help of a walker or crutches next day after surgery, partial weight bearing after 6 weeks and full weight bearing was started after 3 months approximately. However, weight bearing was modified as per the type of fracture, stability of internal fixation, fracture union and tolerance of the patient. Post-operative dressings were done on 2^nd and 5^th day. Suture removal was done on or after 14 days. Follow up was done at 2^nd, 4^th, 6^th week, 3 months, 6 months, and 1 year after the surgery. The patients were assessed functionally on the basis of Harris Hip Score and radiologically. The post-operative pain was assessed as per Hip Score criteria at the end of 1 year along with post-operative gait assessment. Union was decided on the basis of obliteration of fracture line with bridging callus so as to allow unprotected function of the limb.

Harris Hip Scoring System: Formulated by W. H. Harris⁶ it incorporates all-important variables into single reliable figure, which is both reproducible and reasonably objective.

 

Table 1: Point scale with maximum of 100 points:

 

Table 2: Harris hip score

 

Table 3: The score is reported as ⁶

 

RESULTS

This study was conducted on 60 patients (30 patients were in PFN group and 30 patients were in DHS group). Male: Female ratio was 2.75:1 in PFN group and 9:1 in DHS group.

 

Table 1: Distribution of cases according to gender among both groups

 

Table 2: Distribution of cases according to age group

 

In PFN group 15 cases (50%) were having Right side involvement and remaining 15 cases (50%) were having Left side involvement whereas in DHS group 16 cases (53.33%) were having right side involvement and remaining 14 cases (46.67%) were having Left side involvement with p-value =0.796 (NS).

Table 3: demonstrates distribution of cases according to fracture

 

 

Figure 8                                                                                     Figure 9

Figure 8: Distribution according to type of fractures (Boyd and Griffin classification) among both groups

Figure 9: Co-morbid medical illness in both groups

Table 4: Average surgical operative time

 

Figure 10: Average blood loss among both groups Figure 11: Shows complications among both groups

 

                        Figure 12: Shows post-operative gait among both groups Figure 13: Shows post-operative pain among both groups

 

 

Table 5: Comparison of Mean Harris Hip score

 

 

                          Figure 14: Mean Harris hip score among both groups              Figure 15: Shows final outcome among both groups

Table 6: Association between final outcome and fracture outcome

 

Table 8: Comparison of Mean Harris Hip score in stable and unstable cases after 1 year

Figure 16: Pre-operative AP and Lateral radiographs; Figure 17: Post-operative AP and Lateral radiographs; Figure 18: Complication of excessive collapse of DHS screw leading to shortening of 3cms

A 41 - year old female with right sided stable intertrochanteric fracture treated with PFN. (Fig. 19)

1. Pre-operative image
2. and c) Immediate post-operative AP and Lateral radiograph
3. Union at 6 weeks follow-up