Unstable Proximal Femur Transtrochanteric Fractures Treated With Dynamic Hip Screw and ß -Tricalcium Phosphate/ Hemihydrated Calcium Sulfate Graft Scaffold
Phase: NA
Conditions: Proximal Femur Fracture
Sponsor: Hospital Regional Tlalnepantla

Document Cover Page  
  
Official Title of the Study:  
Unstable proximal femur trans trochanteric fractures treated with dynamic hip screw with 
tricalcium B phosphate / hemihydrate sulfate graft scaffold  
NCT Number:   
Not Available  
Date of Document:  
October 3, 2020 
  
 

Title: Unstable proximal femur transtrochanteric fractures treated with dynamic hip screw 
with tricalcium β phosphate / hemihydrate sulfate graft scaffold.  
  
Abstract.  
Transtrochanteric fractures are a frequent entity, principally in patients over 65 years old, 
with low bone density. Most of these fractures of the proximal femur are treated effectively 
with internal fixation with a dynamic hip screw (DHS), nonetheless a conditional factor in 
the treatment success it’s in the fracture stability and in the osteoporosis, severity giving 
way to the most frequent complication, the loosening of the dynamic screw in the femoral 
head which conditions lack of bone healing. The objective of this study was to determine 
the utility of tricalcium β phosphate / hemihydrate sulfate graft as a scaffold to prevent 
loosening of the DHS compared to patients treated with a DHS without graft. Control groups 
were randomized and compared utilizing the Tip to-Apex distance (TAD), 19 patients were 
evaluated in the study group versus 17 in the control group at three different times using 
Student T, ANOVA and Turkey’s post Hoc. Conclusion: The use of tricalcium β phosphate / 
hemihydrate sulfate graft as a scaffold for transtrochanteric unstable fractures proved 
useful to prevent loosening of the DHS  
  
Introduction.  
  
Transtrochanteric fractures are a frequent entity, principally in patients over 65 years old, 
with low bone density, Most of these fractures represent 57% of all proximal femur 
fractures.1 Due to the improvements in the quality of life in elderly adults and longevity 
there’s been an increase in the incidence rates of these fractures in adults after the age of 
80 years.2, 3.The DHS is an implant that biomechanically allows for sliding of the screw 
modifying interfragmentary contact and impeding fracture healing. However, despite being 
an excellent method of fixation, there is still a high incidence of complications in adult 
patients, the most common being loosening of the DHS in the  
femoral head. 4, 5, 6, 7, 8, 9, 10, 11, 12, 13.  
There are various studies that prove the complications of stable transtrochanteric fractures 
utilizing  
DHS as a treatment, but the number of cases on those is small. 8, 14, 15, 16 For stable fractures 
the DHS facilitates bone healing via compression between the fragments, this doesn’t 
happen in unstable fractures where the DHS does not achieve adequate fixation producing 
a larger array of complications (4%-19%). 11,12,13  
  

The failure in the fixation of the screw will result in a migration of itself and a varus collapse 
of the proximal fragment with a loosening of the implant. Eventually there will be a bigger 
space with no support on the screw´s previous position, resulting in a technically demanding 
and complex revision surgery. 5, 6 Consequently, there is controversy whether arthroplasty 
replacement is preferred over osteosynthesis in patients with osteoporosis and unstable 
fractures, however, the risk of periprosthetic infection or increased bleeding during joint 
replacement surgery makes the decision to place a DHS against a prosthesis debated.  
In an attempt to avoid the conditioning factors of failure in the treatment of older adults in 
the DHS implant, various techniques have been described that improve the dynamic screw 
anchorage in the femoral head and neck, as well as to maintain the fragments in a stable 
position. Until the fracture heals, the first is a trochanteric support plate in the shape of a 
racket or star, however it is difficult to obtain in our setting; 17,18. The other alternative is 
augmentation with the application of polymethylmethacrylate cement in the femoral neck 
canal, allowing its inclusion through the bone trabeculae. 19, 20, 21, 22, 23. There is still no 
consensus on which is the best implant or adjuvant system for unstable hip fractures.  
Likewise, a measuring method has been described to evaluate the risk of short-term 
loosening of the DHS system in transtrochanteric fractures, this method is known as the 
Apex-Tip index and is defined as the distance between the tip of the screw and the apex of 
the femoral head on anteroposterior and lateral radiographs, obtaining a score in 
millimeters that allows us to know the risk of loosening of the sliding screw after fixation 
14, 15, 24.  
  
 
 
 
 
  

  
  
Figure 1. Apex – Tip Index = (X ap * V true/ D ap) + (X lat * D True / V lat)  
  
  
  
 

Materials and methods.  
Between April 2016 and June 2018, 36 patients were registered with acute non-pathological 
unilateral transtrochanteric fractures between the ages of 65 and 80, with an average age 
of 72 years, all of whom were treated with closed reduction and internal fixation with the 
DHS system. Before the surgical treatment, the patients were informed of the objective of 
the study and they were given an informed consent, which they signed to be part of the 
study. The surgical procedure was performed under epidural blockade or general anesthesia 
by the same surgeon, a fracture reduction table was used to obtain an alignment as 
anatomically as possible. The DHS System was applied, and it was verified that all the sliding 
screws were centered on the femoral head. For the study group, prior to the introduction 
of the sliding screw, 10 cc of geneX [genex, 700 Military Cutoff Road, Suite 320, Wilmington, NC 28405, USA] in paste 
were applied and its introduction to the femoral head was completed using a cannula. 5.0 
mm twin fix and a cylindrical metal impactor, immediately afterwards the sliding screw was 
inserted, and the DHS plate was fixed with 4.5 cortex screws using the conventional 
technique. Figure 4.  
Both groups were evaluated by measuring the apex-tip index on an anteroposterior and 
lateral radiograph of the proximal femur in the immediate postoperative period and again 
during follow-up with the same radiographic projections at 6 and 12 weeks to compare the 
incidence of loosening.  
Figures 2, 3  
The necessary information was collected from the patients, including demographic 
variables and their results. Data were represented as mean and standard derivation for 
continuous variables or percentages for discrete variables. The p value was established 
before analysis at 0.05 for each test, the logistic regression analysis was analyzed to 
investigate interactions on independent variables and its ability to predict implant 
loosening. Analysis of variance (ANOVA) and Tukey's post hoc test were analyzed for 
multivariate statistical analysis.  
  
  

Results: 
The results of the Tip – Apex Index were obtained where the average for the immediate 
postoperative period was 23.9 for the experimental group and 24.6 for the control group with a 
difference of less that 1 point. At 6 weeks the average for the experimental group was 24.9 and for 
the control group 27.3 where the difference increased to almost 3 point and at 12 weeks 25.6 for  

Statistical analysis  
The experimental group was compared against the control group at three different times 
using Student's t - test. In the immediate postoperative period (0 weeks) the value of t was 
-0.27803. The p value was 0.391; not finding a statistically significant difference for both 
groups with a p <0.05. At 6 weeks the value of t was -0.95573 and the value of p was 0.17, 
not finding a significant difference for p <0.05. However, at 12 weeks the t value was -
1.84694 with a p value of 0.36737 for a p <0.05 finding a significant difference between both 
groups. For the control group, the results were analyzed using ANOVA with a p of 0.04 and 
a Turkey’s post Hoc of 0.035 between the immediate postoperative period and the 3-month 
evaluation. In both tests a significant difference is found.   
  
Discussion.  
Transtrochanteric fractures are one of the most frequent bone entities found in elderly 
patients over 65 years of age, who will also have some degree of osteoporosis. The objective 
of the study was to determine the utility of the absorbable graft of tricalcium ß phosphate 
/ calcium sulfate hemihydrate paste at the time of the placement of the DHS to prevent 
loosening of this in unstable transtrochanteric fractures of the proximal femur compared to 
conventional DHS system placement.   
In the control group to whom the resorbable graft of tricalcium ß phosphate / calcium 
sulfate hemihydrate was not applied, we found a tendency to loosen mainly between 6 and 
12 weeks, essential time for bone consolidation. For the experimental group, no significant 
difference in implant loosening was found between the postoperative period and 3 months, 
resulting in a lower probability of loosening for the group of patients treated with 
absorbable graft of β-tricalcium phosphate / calcium sulfate hemihydrate.   
There is still controversy regarding the decision between osteosynthesis or joint 
replacement treatment when facing an unstable transtrochanteric fracture, when placing 
an osteosynthesis implant with a high technical requirement due to the type of fracture and 
bone conditions inherent to the patient, the risk of loosening is high increasing the 

likelihood of a revision surgery. For this reason, some surgeons prefer to perform a first-
instance primary hip replacement to avoid this scenario. In this study we were able to 
demonstrate the first study comparison of closed reduction and internal fixation  with the 
DHS system associated with resorbable tricalcium ß  phosphate / calcium sulfate 
hemihydrate graft  against closed reduction internal fixation with the conventional DHS 
system placement method in unstable transtorchanteric fractures, however more studies 
to confirm that the use of resorbable tricalcium ß  phosphate / calcium sulfate hemihydrate 
graft is useful to decrease the complications of osteosynthesis in unstable transtrochanteric 
fractures. Without a doubt, this is a step in the right direction to decide to perform 
osteosynthesis instead of joint replacement as the first treatment option.   
  
  
  
  
  
  
 

Conclusion.  
The application of tricalcium ß phosphate / calcium sulfate hemihydrate pastes as a graft 
for the treatment of unstable transtrochanteric fractures with the DHS sliding screw has 
better results avoiding to a greater extent the loosening of the implant during bone healing.  
  
  
 

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INFORMED CONSENT 
 
Title of research: Unstable proximal femur trans trochanteric fractures treated with dynamic hip 
screw with tricalcium B phosphate / hemihydrate sulfate graft scaffold. 
 
 
1. The purpose of this study is to analyze radiographic measurements in patients with hip 
fractures treated with surgery with or without added Calcium Sulfate Scaffold (GeneX) 
2. Upon accepting to enter the study, surgical treatment will be performed according to 
the fracture presented. The surgery consists of fixing the fracture line with 
osteosynthesis material (DHS system), after which X-rays of the injury will be taken at 6 
and 12 weeks. 
3. We expect to have 40 participants for this study, who must be between 65 and 80 years 
old, with an unstable hip fracture and who undergo surgical treatment with the DHS 
system, they must have a follow-up of at least 12 weeks and two X-rays at 6 and 12 
weeks. 
4. Potential risk and discomforts: The risks in this study are specific to the surgical 
treatment to which it will undergo unwanted fracture, no union fracture, soft tissue 
infection, osteomyelitis, dislodging of osteosynthesis material, bleeding, unwanted 
fracture, limb shortening affected, limitation of movement or ambulation, pulmonary 
thromboembolism, sepsis, and death. For the application of calcium sulfate, you could 
present heterotopic ossification which means, extra bone formation. 
5. Potential benefits: Restore function of the affected limb, return to daily activities, 
promote the healing of the fracture. 
6. Confidentiality: All the information collected in this study will be encrypted to protect 
the identity of each participant, the researcher will securely maintain the files and data 
collected electronically. 
7. The decision to participate in this study is completely voluntary, if you do not wish to 
participate in this study, the care, services, or benefits to which you are entitled will not 
be affected. 
8. If you decide to participate in this study, you can withdraw or withdraw at any time 
without retaliation. 
9. This study is at no cost to participants. 
 
 
 
I voluntarily agree to participate in this research program 
□ Yes 
□ No 
I understand that I will be given a copy of this signed Consent Form. 
 
 
Name of Participant (print):                             Signature:                             Date:                       . 
                                                                   
Name of Witness (print):                                  Signature:                             Date:                       . 
 
25. Person Obtaining Consent:                            Signature: