In this study have been proposed a novel radiation-free technique, using laser light to target the cross lock of the IMN. To achieve optimal wavelength, transmittance and reflectance spectroscopy of biological tissues were performed. Then, intramedullary nail holes laser indicator was made based on spectroscopy results. Animal and human tests were performed to evaluate the performance of the proposed technique. Figure 1 shows the study flow diagram.
Spectroscopy of biological tissues. We performed Ex-Vivo spectroscopy of biological tissues including bone, fat, tendon, muscle, and skin. Samples were prepared in dimensions of 30×30±2mm and 2-4mm thickness from cow and sheep legs which were supplied from the Zarrinshahr slaughterhouse, Iran. Two homemade spectroscopy setups were utilized: one for obtaining the reflectance spectrum (Fig. 2-A) and another was designed for transmittance measurements (Fig. 2-B). The reflectance measurements performed by a reflective probe mounted on a holder base which is placed at 5 mm hight from the sample. This reflective probe consists of seven optical fibres (750 µm, NA=0.47 PMMA Optical Fibre-Mitsubishi Electric Co-Tokyo-Japan) which the middle one is coupled to the xenon source (ASB-XE-175-Spectral Products Co- Putnam-US) by a lens array. The induced light to the sample surface is collected by six side fibres and then the reflected spectrum is monitored by an optical spectrometer (Spectronix Ar 2015v- Teifsanje Co-Tehran-Iran). To eliminate the source spectral characteristics, a BaSO4 pill was used as a reference. We molded 4.49gr of BaSO4 powder (CAS Number: 7727-43-7-Titrachem Co-Iran) in 250mpa pressure. The reflectance spectrum of the homemade BaSO4 pill was collected and divided by the source spectrum yielding a flat spectral response through the visible spectrum.
Two lens arrays are utilized to obtain the transmittance spectrum, one mounted on the holder base for focusing the xenon light on the sample, and the second mounted in front of the first array to collect transmitted rays. The sample mounted on a sample holder in the proper distance from the lens arrays.
Intramedullary nail holes laser indicator. As shown in figure 3-A, the intramedullary nail holes laser indicator consists of a 680 nm-350mW solid-state laser and a flexible biocompatible probe. The laser light is guided through the designed probe and then passes through the IMN hole, making the position of the IMN hole appears on the skin for the naked eyes. This portable device capable of washing, disinfecting, and autoclaving. Moreover, it uses a rechargeable lithium battery and can provide constant optical power during operation. Figure 3-B shows a schematic image of positioning IMN hole using the intramedullary nail holes laser indicator.
Evaluate the intramedullary nail holes laser indicator in animal tests. Measurements were performed on 10 animal samples, 5 sheep's legs, and 5 cows' legs which were supplied from the Zarrinshahr slaughterhouse, Iran. Sheep's samples had a small diameter between 16 and 21 mm and a large diameter between 29 and 35 mm. Also, the cows' samples had a small diameter between 40 and 48 mm and a large diameter between 65 and 73 mm. For each sample, intramedullary nailing (Pooyandegan Pezeshki Pardis-Golestan-Iran) was performed inside the tibia bone, and distal locking was done three times using the laser intramedullary nail holes indicator. Figure 4, shows intramedullary nailing procedures for one of the samples.
Output parameters were procedure time and drilling quality. The procedure time as one of the performance parameters is defined as the total time needed between determining the position of the IMN hole and checking the screw insertion. Another performance parameter is the drilling quality which is evaluated as follows: 3 points for successful operation and if the drill does not hit the nail, 2 points for successful operation but with a slight collision with the nail,1 point for severe interference of the drill with nail (in this case, the drilling site must be corrected), 0 point in case of failure. Mean value, standard deviation, and p-value were calculated for both the procedure time, and drilling quality. Paired t-tests were used to compare these performance parameters for cows' and sheep`s samples considering α=0.05.
Evaluate the intramedullary nail holes laser indicator in a human test. The evaluation was performed on a middle-aged man with an acute tibia and fibula fracture of the distal area of the right leg. The study was approved by the ethics committee of the Shohada Lenjan Hospital, Iran, in January 2020. Also, informed consent of participating was obtained and the study was performed under relevant guidelines and regulations. Figure 5-A illustrates an X-ray image of the patient's right leg before the surgery.
Intramedullary nailing was performed using a tibia nail and three locking screws (Osveh Asia Medical Instrument Co - Iran). By utilizing the intramedullary nail holes laser indicator, finding drilling position, incisions skin, and drilling toward the IMN hole performed in a dark surgery room. Then, fastening the locking screw was performed in the natural light of the surgery room. Distal and proximal interlocking performed successfully for one hole in the distal area and two holes in the proximal area with no errors. Figure 5-B finding drilling position by the intramedullary nail holes laser indicator in the dark surgery room, and figure 5-C shows interlocking the IMN. Figure 5-D shows the X-ray image of the right patient's foot one day after surgery.