1 Introduction
Intertrochanteric fractures are mostly common in the elderly population[1] [2] [3] [4] [5] PFNA ) were included in methods of intramedullary fixation. PFNA -II is specially designed for the Asian population, and accommodates the anatomic characteristics of Asian.[6] [7,8] [8] [8,9] [10,11] PFNA -II for femoral intertrochanteric fracture.
2 Materials and methods
2.1 Patients
The present study was a retrospective study including patients managed operatively in Department of Orthopedics, Suzhou Municipal Hospital between January 2015 and November 2018. Finally, the study included 70 patients treated with PFNA -II for femoral intertrochanteric fracture. Mean age of patients was 79.9 years (ranged from 45–98 years old), 46% male gender. Time interval from injury to operation was 2 to 6 days. Fractures were classified on the basis of the AO classification, 31. A1-A3. We reviewed all patients’ electronic medical records retrospectively. We recorded variables such as age, gender, height, weight, BMI, preoperative and postoperative hematocrit (Hct) levels, intraoperative blood loss (IBL), operation time, length of hospital stay (LOS), and fracture classification. Written informed consents were obtained from all the participants, and this study was approved by the responsible Human Participants Ethics Committee of the Suzhou Municipal Hospital (No. KL901030, date: December 1, 2014).
2.2 Inclusion criteria and exclusion criteria
All included patients meet the criteria, which included:
1. patients with a confirmed diagnosis of unilaterally acute and closed intertrochanteric fracture and fracture classified according to AO type on X-ray or computed tomography (CT);
2. the following data were provided: height, weight, blood routine results at the third day preoperatively and postoperatively;
3. fracture was treated with closed reduction and PFNA -II fixation;
4. the amount of rehydration did not exceed 2000 ml;
5. the prothrombin time (PT) and activated partial thromboplastin time (APTT) were in the normal range;
6. no serious liver or kidney and no history of digestive tract bleeding.
The exclusion criteria include patients without postoperative images and non-standard placement of implant, with lower extremity arteriosclerosis obliterans, receiving anti-coagulation therapy (e.g. low molecular weight heparin or NOACs) or hemostatic therapy pre- or before a blood routine test obtained on the second or third postoperative day and failure of internal fixation.
2.3 Management of blood loss
A team of senior surgeons performed all the operations following a standard surgical technique recommended by the manufacturer (PFNA -II, Sunan Temed, China). IBL was evaluated by the measured suction loss and blood loss in swabs, and recorded by the anesthetists. No patients obtained wound drainage. Thus, the OBL was equal to IBL. Additionally, a blood routine test, including Hct levels, was obtained preoperatively and on the second or third postoperative day for calculation of blood loss.
2.4 Calculation of HBL
According to methods provided by Gross et al,[12]
Hctpre is the preoperative Hct, Hctpost is the Hct on the second or third day postoperatively, and Hctave is the average of the Hctpre and the Hctpost .
PBV was calculated according to methods provided by Nadler formula Sehat et al,[13]
k1 = 0.3669, k2 = 0.03219 and k3 = 0.6041 for males, and k1 = 0.3561, k2 = 0.03308 and k3 = 0.1833 for females.
In addition, on the basis of methods provided by Sehat et al,[14]
2.5 Calculation of R
According to postoperative X-ray results, the ratios of marrow cavity diameter to intramedullary nail diameter from different layers, including start of funnel, end of funnel and femoral isthmus, were measured. The mean of the ratio from frontal and lateral X-ray were designated as R . We classified the all included participants into a high matching group and a low matching group according to z-score of R within each layer. All individuals reporting a z-score < 0 were considered as belonging to a high matching group. Conversely, individuals with a z-score ≥ 0 were considered as belonging to a low matching group. In addition, TBL, HBL, and OBL were compared between the 2 groups. We applied multiple linear regression analysis between the HBL as a dependent variable and age, fracture type and R as independent variables. Figure 1 showed the start of funnel, end of funnel, and femoral isthmus in frontal and lateral X-ray.
Figure 1: (A) Frontal and (B) lateral X-ray images of intertrochanteric fractures. a and a’, start of funnel; b and b’, end of funnel; c and c’, femoral isthmus.
2.6 Statistical analysis
The statistical analyses were implemented with SPSS 21.0 software. Statistical threshold was set at a P < .05.
Ratio statistics were applied to calculate the ratio of HBL to TBL in different groups. Normal distribution for continuous data was assessed by the Kolmogorow–Smirnoff test. For continuous data with a normal distribution we used an independent-samples t test for independent samples; the Mann–Whitney test was used when normality was rejected. Independent-samples t test and Chi-Squared test were performed to compare the demographic data, TBL, HBL, and OBL between low matching group and high matching group. A step-wise multivariate linear regression analysis was performed to relate several independent factors, including age, gender, BMI, fracture type, R in different layers, to HBL.
3 Results
According to the z-scores of R of start of funnel, included individuals were divided into the 2 groups: low matching group (n = 31) and high matching group (n = 39). Ratio statistics indicated that HBL accounted for approximately 80% of TBL (84.7% in low-matching group and 78.0% in high-matching group, respectively). Table 1 showed demographic data, TBL, HBL, and OBL between the 2 groups. Figure 2 showed TBL, HBL, and OBL comparisons between the 2 groups. Independent-samples t tests indicated no significant difference in age and BMI between the 2 groups. A Chi-Squared test indicated no significant difference in gender and fracture AO types between 2 groups. Independent-samples t tests showed decreased TBL and HBL in low-matching group, compared to high-matching group, whereas it showed no significant difference in OBL between the 2 groups.
Table 1: Demographic data and blood loss for included patients, who were grouped according to z-score of R (the ratios of marrow cavity diameter to intramedullary nail diameter) from start of funnel.
Figure 2: Blood loss for included patients, who were grouped according to z-score of R (the ratios of marrow cavity diameter to intramedullary nail diameter) from start of funnel.
On the basis of the z-scores of R of end of funnel, we classified included individuals into the 2 groups: low matching group (n = 29) and high matching group (n = 41). Ratio statistics showed that HBL accounted for approximately 80% of TBL (87.3% in low-matching group and 76.5% in high-matching group, respectively). Table 2 showed demographic data, TBL, HBL, and OBL between the 2 groups. Figure 3 showed TBL, HBL, and OBL comparisons between the 2 groups. Independent-samples t tests showed no significant difference in age and BMI between the 2 groups. A Chi-Squared test indicated no significant difference in gender and fracture AO types between the 2 groups. Independent-samples t tests showed decreased TBL and HBL in low-matching group, compared to high-matching group, whereas it showed no significant difference in OBL between the 2 groups.
Table 2: Demographic data and blood loss for included patients, who were grouped according to z-score of R (the ratios of marrow cavity diameter to intramedullary nail diameter) from end of funnel.
Figure 3: Blood loss for included patients, who were grouped according to z-score of R (the ratios of marrow cavity diameter to intramedullary nail diameter) from end of funnel.
According to the z-scores of R of femoral isthmus, we divided included patients into the 2 groups: low matching group (n = 32) and high matching group (n = 38). Ratio statistics indicated that HBL accounted for approximately 80% of TBL (84.5% in low-matching group and 77.9% in high-matching group, respectively). Table 3 showed demographic data, TBL, HBL, and OBL between the 2 groups. Figure 4 showed TBL, HBL, and OBL comparisons between the 2 groups. Independent-samples t tests indicated no significant difference in age and BMI between the 2 groups. A Chi-Squared test indicated no significant difference in gender and fracture AO types between the 2 groups. Independent-samples t tests showed decreased TBL and HBL in low-matching group, compared to high-matching group, whereas it showed no significant difference in OBL between the 2 groups.
Table 3: Demographic data and blood loss for included patients, who were grouped according to z-score of R (the ratios of marrow cavity diameter to intramedullary nail diameter) from femoral isthmus.
Figure 4: Blood loss for included patients, who were grouped according to z-score of R (the ratios of marrow cavity diameter to intramedullary nail diameter) from femoral isthmus.
Multivariate linear regression analysis indicated that the ratios of marrow cavity diameter to intramedullary nail diameter measured in start of funnel, end of funnel layers were significantly associated with HBL, whereas age, gender, BMI, and fracture type were not significantly correlated to HBL (Table 4 ).
Table 4: Multiple linear regression analysis on influential factors of HBL in each group.
4 Discussion
The present study indicated that the ratios of marrow cavity diameter to intramedullary nail diameter measured in start of funnel, end of funnel layers were significantly associated with HBL, whereas age, gender, BMI and fracture type were not significantly correlated to HBL.
The concept of HBL was firstly proposed by Sehat et al.,[14] [15] [16] PFNA for intertrochanteric fractures. These results were corresponding to our result that HBL accounted for approximately 80% of TBL. Until now, the causes and mechanism of HBL are not yet clear. Intertrochanteric fracture belongs to fractures of the metaphysis with rich blood supply. The process of expanding the medullary cavity could lead to internal bleeding after the intramedullary needle was fixed. Additionally, the intramuscular gaps and intramedullary cavities could also provide storage cavities for HBL. Smith[17] [18–21] [22] [15]
Notably, the present study indicated that the ratios of marrow cavity diameter to intramedullary nail diameter measured in start of funnel, end of funnel layers were significantly associated with HBL. Combined with the causes of HBL, we speculated 3 possible reasons:
1. The internal fixation system with a better overall matching degree is more stable, which might reduce the fretting at the fracture end, and reduce bleeding from fractures caused by fretting;
2. After the reaming, a large amount of cancellous bone bed in the proximal femur began bleeding. Better matching degree of the intramedullary nail in the proximal femur might contribute to tighter compression of entire infundibulum to the reamed cancellous bone bed in the proximal part of the femur, which plays a certain role in hemostasis;
3. Better matching degree at the end of the funnel contributes to more effective isolation of medullary cavity at the fractured end from medullary cavity of total femoral, preventing perioperative blood pouring into the tissue compartments and free fatty acids entering the blood circulation.[23]
The present study provided evidence to support that the ratios of marrow cavity diameter to intramedullary nail diameter might be an important factor for HBL in the perioperative period during PFNA -II stabilization for femoral intertrochanteric fracture. However, the present study showed that age, gender, BMI, and fracture type were not significantly correlated with HBL. The results were consistent with 2 recent studies, which revealed that HBL was not associated with age, gender, BMI, percentage of height loss, percentage of height restoration, fracture type, or operation time with multivariate linear regression analysis.[10,11] 2 , admission specific gravity of urine <1.020, fracture type, and admission albumin <30 g/L were associated with a greater likelihood of larger HBL.[24]
The study explored the effect of the ratios of marrow cavity diameter to intramedullary nail diameter on blood loss during perioperative period regarding different layers, including start of funnel, end of funnel, and femoral isthmus. Due to the different proximal femur shape, the matching levels of different layers are not necessarily the same in themselves. This study tried to find out which layer is most closely related to blood loss. According to our result, the HBL was obviously associated with the ratios of marrow cavity diameter to intramedullary nail diameter obtained from end of funnel, which revealed that the indices could work as important evaluation indices for intramedullary nail. We could select the appropriate intramedullary nail with high matching degree from end of funnel with the help of software simulation or imaging template.
The limitations of this study include that our sample size was small, and the results may be biased as a consequence.
5 Conclusion
In conclusion, matching rate of PFNA II at the funnel might be an important factor for HBL and TBL postoperatively. It is essential that the appropriate intramedullary nail should be timely adjusted according to the matching degree during the operation. In addition, the study provided evidence for the improvement of the intramedullary nail in the future.
Author contributions
Conceptualization: Xiao Yu.
Data curation: Hong Zhang, Xiangxin Zhang, Renjie Xu, Yuanshi She, Zhaohen Yu, Guangxiang Chen.
Methodology: Xiao Yu, Hong Zhang, Xiangxin Zhang, Renjie Xu, Yuanshi She, Zhaohen Yu, Guangxiang Chen.
Supervision: Hong Zhang.
Writing – original draft: Xiao Yu.
Writing – review & editing: Hong Zhang.
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