Functional Outcomes of the Knee after Retrograde and Antegrade Intramedullary Nailing for Femoral Shaft Fractures

Njoroge AN1, Mwangi HR2, Lelei LK1

1 − School of Medicine, Moi University

2 − Moi Teaching and Referral Hospital

Correspondence to: Dr. A. N. Njoroge, P. O. BOX 4606-30100, Eldoret, Kenya, Email: tonnynduati@gmail.com

Abstract

Background: Antegrade intramedullary nailing is currently considered the gold standard for treatment of femur shaft fractures although retrograde technique is gaining acceptance. Although introducing the nail through the knee has potential to damage the intra articular structures, several reports have indicated acceptable functional outcome. The results are not known in our centre that so far lacks an established patient selection and knee rehabilitative protocols in-spite of the widespread use of the retrograde technique. Objective: To compare the functional outcome of the knee joint after retrograde and antegrade intramedullary nailing of femoral shaft fractures.

Methods: A comparative cross sectional study carried out on patients who were treated with retrograde and antegrade intramedullary nailing for femoral shaft fractures between January 2007 and December 2009.

Functional outcome was determined using modified HSS score.

Results: A total of 124 patients participated in the study. According to the modified H.S.S knee rating system, overall, functional results were rated as excellent in 71.8%, good in 23.4% and poor in 3.2%.The retrograde group had poorer results than Antegrade group (p<0.001). There was a negative correlation between age and the functional outcome in the retrograde group (p < .001).The incidence of knee pain was higher in the retrograde group (37.5%) as compared to 10% in the Antegrade group, while the rate of knee stiffness was higher in the retrograde group (40.6%) compared to the Antegrade group (3%).

Conclusion: Retrograde nailing is associated with poorer knee scores in our patient population. Increasing age is a factor associated with poorer scores especially after retrograde nailing.

Background

Antegrade approach to the femur for intramedullary fixation of shaft fractures has been extensively described with union rates as high as 99% and has been considered the gold standard to date (1-5). However, retrograde approach through the femoral intercondylar notch has been popularized in the recent years as an alternative to antegrade nailing (6-12). The SIGN® nail is a solid interlocking intramedullary device designed, manufactured and distributed by Surgical Instrument Generation Network (SIGN). The nail is designed for use in femur, tibia and humerus shaft fractures. It is designed for insertion without fluoroscopy or use of fracture table. Availability of the SIGN® nail in our setting and a number of peripheral hospitals in Kenya has provided orthopedic surgeons in these areas with an opportunity to use the interlocking nail to treat femoral shaft fractures in such resource poor settings (13). Retrograde nailing has potential of violating intraarticular structures and cartilage, raising the fear of knee complications and deterioration of knee function (14, 15). Studies looking at functional outcomes after retrograde nailing have reported acceptable results (16, 17).

 

However these studies have been performed using different types of nails, specifically designed for retrograde use, predominantly closed reduction of fractures and with specific post-operative rehabilitation by continuous passive motion or physical therapy of the knee (16-19). The use of continuous passive motion functional training of the knee after intramedullary nailing of the femur has been shown to be a significant determinant of outcome highlighting the importance of a postoperative knee rehabilitation protocol (20).

 

 

In the setting of this study, there is no established protocol of knee rehabilitation after antegrade or retrograde nailing. Furthermore, the fractures were reduced mainly by open method and this has potential to violate the extensors of the knee. This study compares the knee functional outcomes after retrograde and Antegrade nailing and evaluates its association with gender, fracture level and fracture type in our patient population. The results of this study are a first step in drawing patient selection.

 

Methodology

We carried out a hospital based cross sectional study in a 712-bed capacity Teaching and Referral Hospital in Western Kenya among patients aged 16 years and above who had undergone intramedullary fixation of femur shaft fractures using the SIGN® nail between January 2007 and December 2009. The participants  clinical and demographic data was retrieved from their records and entered into a data sheet. Clinical examination of the knees was conducted and a goniometer was used to determine active range of motion. Fractures were classified according to the AO/OTA classification of fractures, while outcomes were determined using the modified Hospital for Special Surgery (H.S.S) knee functional score (16). Patients with obvious knee trauma/pre-existing knee pathology, incomplete medical records, bilateral femoral fractures or floating knee were excluded from the study leaving 124 patients in our study. Data analysis was done using SPSS version19 and the p value was set at ≤0.05.

 

Results

The ages of the study population ranged between 16 to 84 years with a mean age of 38.8 +15.4 years. The male to female ratio was 3.3:1. On average, the duration between injury and nailing was 10 +7.2 days, with a range of 0 to 40 days. The average follow-up (time of surgery to study) for retrograde group (70 weeks) and antegrade group (65 weeks) was not significantly different (p>0.05). All fractures were reduced by open method as per the SIGN® Technical Manual. The retrograde method of nailing was used in 51.6% of the cases while antegrade accounted for 48.4%.In the retrograde group (N=64), all the fractures were either in the lower (60%) or middle third (40%) of the femoral shaft. While in the antegrade group (N=60), the level of fractures was 32%, 65% and 2% for upper, middle and lower 1/3rds of the femoral shafts respectively.

Click to view figure 1.

 

As shown in figure1, 98.3% and 92.2% of patients had excellent or good outcomes in the antegrade and retrograde groups respectively. Fifty per cent of patients in the retrograde group had excellent outcomes as compared to 95% in the antegrade group (p<0.001). Overall there was a negative relationship between knee scores and the age of the patients, r = -.42, p <.001. The relationship between age and the outcome was not significant in antegrade group (r= -.085, p=0.519), but was significant in retrograde (r= -.445, p<0.001).

 

The differences in the average functional scores for the different fracture levels in the antegrade or retrograde group were not statistically significant: antegrade group p=0.82, retrograde group p=0.286.

 

Overall, male patients had insignificantly greater modified knee ratings x̅ = 90.05, than their female counterparts x̅= 86.21, (p >0.05).

 

Click to view table 1

 

The prevalence of knee pain was significantly higher in the retrograde group (37.5%) as compared to 10% in the antegrade group (p<0.001). The whole study population had 23% incidence of knee stiffness. In the individual groups, the rate of knee stiffness was significantly higher in the retrograde group (40.6%) compared to the Antegrade group (3%)(p<0.001).