Improved lag screw positioning in the treatment of proximal femur fractures using a novel computer assisted surgery method: a cadaveric study

Abstract

BackgroundThe importance of the tip-apex distance (TAD) to predict the cut-out risk of fixed angle hip implants has been widely discussed in the scientific literature. Intra-operative determination of TAD is difficult and can be hampered by image quality, body habitus, and image projection. The purpose of this paper is to evaluate, through a cadaveric study, a novel computer assisted surgery system (ADAPT), which is intended for intraoperative optimisation of lag screw positioning during antegrade femoral nailing. A 3D measure for optimal lag screw position, the tip-to-head-surface distance (TSD), is introduced.Methods45 intra-medullary hip screw procedures were performed by experienced and less experienced surgeons in a cadaveric test series: in 23 surgeries the ADAPT system was used, and in 22 it was not used. The position of the lag screw within the femoral head and neck was evaluated using post-operative CT scans. TAD, TSD, fluoroscopy as well as procedure time and variability were assessed.ResultsThe use of the ADAPT system increased accuracy in TSD values (i.e. smaller variability around the target value) for both groups of surgeons (interquartile range (IQR) of experienced surgeons: 4.10 mm (Conventional) vs. 1.35 mm (ADAPT) (p = 0.004)/IQR of less experienced surgeons: 3.60 mm (Conventional) vs. 0.85 mm (ADAPT) (p = 0.002)). The accuracy gain in TAD values did not prove to be significant in the grouped analysis (p = 0.269 for experienced surgeons; p = 0.066 for less experienced surgeons); however, the overall analysis showed a significant increase in accuracy (IQR: 4.50 mm (Conventional) vs. 2.00 mm (ADAPT) (p = 0.042)). The fluoroscopy time was significantly decreased by the use of the ADAPT system with a median value of 29.00 seconds (Conventional) vs. 17.00 seconds (ADAPT) for the less experienced surgeons (p = 0.046). There was no statistically significant impact on the procedure time (p = 0.739).ConclusionsThe ADAPT system improved the position of the lag screw within the femoral head, regardless of the surgeon’s level of clinical experience, and at the same time decreased overall fluoroscopy usage. These positive effects are achieved without increasing procedure time.

Numerical Optimization of the Position in Femoral Head of Proximal Locking Screws of Proximal Femoral Nail System; Biomechanical Study

“…Screw positions were evaluated with the lag screw and proximal bone fragment (head and neck) and the safest seemed to be inferior middle and inferior posterior positions. A navigation system improved the lag screw position according to Regling et al ( 19 ) cadaveric study in operations carried out by less experienced and experienced surgeons and the median TAD was 12 mm and 13 mm, respectively. In another study, Hrubina et al ( 9 ) reported 297 patients with 308 hips treated with a dynamic hip screw; the complication rate was reported as 10% and the re-operation rate as 3.9%.…”

Accuracy analysis of computer-assisted surgery for femoral trochanteric fracture using a fluoroscopic navigation system: Stryker ADAPT®system

“…[4][5][6][7] However, ADAPT is not yet widely adopted, and there exist only a few reports about ADAPT. [8,9] We reported the accuracy analysis of ADAPT in this study.…”

How to get better TAD? Relationship between anteversion angle of nail and position of femoral neck guide pin during nailing of intertrochanteric fractures

“…However, intraoperative determination of TAD is difficult and can be hampered by Fig. 1 The guide pin-shaft angle and anteversion before (a,∠α1; c, ∠β1) and after (b, ∠α2; d, ∠β2) the adjustment of the guide pin measured for one included patient the image quality, body habitus and image projection [14,15]. The repetitive adjustment of the main intramedullary nail and guide pin under the C-arm machine or a wide range of stripping and exposure may further increase the operative and fluoroscopy time and cause more complications and instability, especially for the surgeons who are lack of experience [16][17][18][19].…”

“…The TAD should be less than 25 or 27 mm in order to reduce the complications of the cut-out and nail breakage, fracture non-union and poor functional outcomes [ 9 – 13 ]. However, intraoperative determination of TAD is difficult and can be hampered by the image quality, body habitus and image projection [ 14 , 15 ]. The repetitive adjustment of the main intramedullary nail and guide pin under the C-arm machine or a wide range of stripping and exposure may further increase the operative and fluoroscopy time and cause more complications and instability, especially for the surgeons who are lack of experience [ 16 – 19 ].…”