Computer-Assisted Surgery for Internal Fixation of Peritrochanteric Femur Fractures: A Randomized Controlled Study
Phase: NA
Conditions: Hip Fractures
Sponsor: Columbia University

 
 
 
 
 
 
 
 
Computer-Assisted Surgery for Internal Fixation of 
Peritrochanteric Femur Fractures: A Randomized 
Controlled Study 
 
NCT04528459 
IRB approval: December 9, 2020 
 
 

BACKGROUND 
 
Peritrochanteric femur fractures are the most common type of fracture requiring 
orthopaedic surgical intervention. Successful surgery with cephalomedullary nail fixation can 
restore patients' baseline ambulatory function and prevent complications resulting from 
prolonged bedrest and immobilization. However, failure of fixation due to lag screw cut-out has 
an incidence rate of nearly 8% following open reduction internal fixation with an 
cephalomedullary nail. Given this high rate of failure, prior investigations have identified the 
strongest predictor of screw cut-out following cephalomedullary nail fixation, tip-apex distance 
(TAD) of the lag screw. TAD is defined as the sum of the distance from the tip of the lag screw 
to the apex of the femoral head on the anteroposterior and lateral radiographs. A TAD distance 
of greater than 25mm has been shown to be a strong predictor of screw cut-out and fixation 
failure. Although use of intraoperative two-dimensional (2D) fluoroscopy helps guide the 
operator on optimal lag screw placement, the femoral head is a three-dimensional (3D) spherical 
anatomic structure that is difficult to visualize using fluoroscopy alone. Computer navigation 
platforms have been developed to help reliably obtain a TAD of less than 25 mm, potentially 
reducing the risk of lag screw cut-out and failure. To date, however, only one clinical study has 
compared computer navigation to traditional fluoroscopy in achieving a TAD of less than 25 mm 
(Herzog et al. 2019). While this study demonstrated significantly improved accuracy of lag 
screw placement in the computer navigation cohort with no significant effect on average 
operating time, the study did not assess several other important variables nor did it report rates of 
lag screw cut-out. Despite the potential benefits of computer navigation, fluoroscopy remains the 
current standard of care for inserting cephalomedullary nails in the treatment of intertrochanteric 
femur fractures. 
The purpose of this study is to evaluate the ADAPT (Adaptive Positioning Technology, 
Stryker©, USA) computer navigation platform in a controlled, randomized fashion to determine 
its effect on TAD, lag screw cut-out, operative time, fluoroscopy time and number of Kirschner 
wire (K wire) passes prior to insertion of the final implanted device. Additionally, 1 year follow-
up will compare postoperative complications, mobility, range of motion, social dependency and 
pain level between procedures that utilized the ADAPT platform and those that did not. 
 

Study Design: This will be a prospective, randomized, double-blind, controlled trial with 
two treatment cohorts. Cohort 1 will consist of 30 patients with closed peritrochanteric femur 
fractures who undergo open reduction internal fixation with a Stryker© Gamma intramedullary 
nail using traditional fluoroscopy for insertion of the lag screw (control group). Cohort 2 will 
consist of 30 patients with closed peritrochanteric femur fractures who undergo open reduction 
internal fixation with a Stryker© Gamma intramedullary nail using the Stryker© ADAPT 
platform to assist with insertion of the lag screw (treatment group). Patients will be blinded to 
treatment group allocation as will clinicians/researchers during data processing/analysis. The 
primary outcome will be TAD, as measured on AP and lateral hip radiographs. Secondary 
outcomes will be position of the lag screw as described by Cleveland et al, operative time, 
fluoroscopy time, and number of K wire passes prior to final placement of the lag screw. 
Additionally, evidence of lag screw cut-out on hip radiographs, hip range of motion relative to 
the contralateral hip, mobility and social dependency as defined by the Harris Hip Score, and 
pain level (visual analog scale) will be assessed at 3 month, 6 month, 1 year, and 2 year follow 
up visits. 
Statistical Procedures: Descriptive statistics will be calculated to compare patient 
demographics between the two cohorts. The Student t-test and the Fisher’s exact test will be used 
to compare outcomes between the two cohorts. Based on a previous study by Herzog et al 
(2019), we expect the ADAPT platform to lead to an average reduction in TAD of 8 mm (24.9 
mm +/- 6.68 mm without ADAPT vs. 16.9 mm +/- 6.30 mm with ADAPT). Accordingly, in order 
to achieve a power of 0.8 with an alpha of 0.05 and a beta of 0.2, we will need to accrue 11 
patients per cohort. Our plan is to enroll 30 patients per cohort. 
 
RESEARCH AIMS & ABSTRACTS 
 
Research Question(s)/Hypothesis(es): We hypothesize that use of the ADAPTTM 
platform will lead to a lower mean TAD and a greater proportion of patients with a TAD of 25 
mm or less. We do not expect a difference in the proportion of patients with optimal lag-screw 
position within the femoral head as defined by Cleveland et al. Use of the ADAPT platform will 
lead to no difference in operative time or blood loss, decreased fluoroscopy use, and fewer K 
wire passes. In terms of radiographic evidence of screw cut-out, we expect no difference at any 

of the follow up visit time points. Additionally, we expect no difference in hip range of motion, 
mobility and social dependency as defined by the Harris Hip Score, or pain level at any of the 
follow up visit time points.  
Scientific Abstract: Peritrochanteric femur fractures are the most common type of 
fracture requiring orthopaedic surgical intervention. Successful treatment with cephalomedullary 
nail fixation can restore patients' baseline ambulatory function and prevent complications 
associated with prolonged bedrest and immobilization. However, failure of fixation due to lag 
screw cut-out has an incidence rate of nearly 8% following open reduction internal fixation with 
a cephalomedullary nail. Previous research has identified the tip-apex distance (TAD) of the lag 
screw as the strongest predictor of lag screw cutout. Accordingly, computer navigation platforms 
have been developed to reliably achieve a TAD of less than 25 mm. To date, however, only one 
clinical study has compared computer navigation to traditional fluoroscopy in achieving a TAD 
of less than 25 mm. While this study demonstrated significantly improved accuracy of lag screw 
placement in the computer navigation cohort with no significant effect on average operating 
time, the study did not assess other important intraoperative variables nor postoperative 
outcomes. The purpose of this study is to determine if computer navigated lag screw placement 
during cephalomedullary nail fixation utilizing the novel ADAPT platform will lead to a lower 
mean TAD and a greater proportion of patients with a TAD of 25 mm or less. This will be a 
prospective, randomized, single-blinded, controlled trial with two treatment cohorts. Cohort 1 
will consist of patients with closed peritrochanteric femur fractures who undergo open reduction 
internal fixation with a Stryker© Gamma cephalomedullary nail using traditional fluoroscopy for 
insertion of the lag screw. Cohort 2 will consist of patients with closed peritrochanteric femur 
fractures who undergo open reduction internal fixation with a Stryker© Gamma 
cephalomedullary nail using the Stryker© ADAPT platform to assist with insertion of the lag 
screw. Patients will be blinded to treatment group allocation but clinicians/researchers will not. 
The primary outcome will be TAD as measured on postoperative AP and lateral hip radiographs. 
Secondary outcomes will be position of the lag screw as described by Cleveland et al, operative 
time, fluoroscopy time, and number of K wire passes prior to final placement of the lag screw. 
Additionally, evidence of lag screw cut-out on postoperative hip radiographs, hip range of 
motion relative to the contralateral hip, mobility and social dependency as defined by the Harris 
Hip Score, and pain level will be assessed at 3 month, 6 month, 1 year, and 2 year follow up 

visits. Student t-test and Fisher's exact test will be used to compare outcomes between the two 
cohorts. 
Hip fractures are common injuries in which the top part of the femur bone breaks. These 
fractures often require surgery and are frequently treated with a metal rod that goes inside the 
femur, known as a cephalomedullary nail. Successful treatment of hip fractures with a 
cephalomedullary nail can allow patients to start walking soon after surgery. However, the 
cephalomedullary nail must be inserted into the correct position in the femur, otherwise it may 
not work properly. Traditionally, surgeons use x-rays in the operating room to determine if a 
cephalomedullary nail is in the correct position within the femur. Recently, however, computer 
navigation technology has been developed to help surgeons correctly position cephalomedullary 
nail devices. To date, only one study has compared x-rays to computer navigation technology in 
the treatment of hip fractures. While this study demonstrated more accurate placement of the 
cephalomedullary nail with computer navigation, the study did not consider other important 
outcomes such as radiation exposure, hip function and pain after surgery. The purpose of this 
study is to further compare x-rays and computer navigation (the ADAPT platform) for the 
placement of a cephalomedullary nail when treating hip fractures. This study will have two 
groups: group 1 will consist of patients with hip fractures who undergo surgery with a 
cephalomedullary nail using only x-rays, and group 2 will consist of patients with hip fractures 
who also undergo surgery with a cephalomedullary nail but using computer navigation (the 
ADAPT platform) as well as x-rays. X-rays taken after surgery will be used to compare the 
average position of the cephalomedullary nail in the femur between the two groups. Other 
variables will also be compared between the two groups including the average time required to 
perform the surgery, the average number of x-rays taken during the surgery, the average number 
of attempts required to position the cephalomedullary nail, as well as the occurrence of signs on 
x-ray that suggest the cephalomedullary nail is not functioning properly, average hip range of 
motion, mobility, independence, and pain at 3 months, 6 months, 1 year and 2 years after surgery. 
 
 
 
 
 

REFERENCES 
 
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