An Easy and Economical Way to Produce a Three-Dimensional Bone Phantom in a Dog with Antebrachial Deformities

animals

Article An Easy and Economical Way to Produce a Three-Dimensional Bone Phantom in a Dog with Antebrachial Deformities

1,2, 1,3, 1 Hee-Ryung Lee †, Gareeballah Osman Adam † , Dong Kwon Yang , Tsendsuren Tungalag 1, Sei-Jin Lee 4 , Jin-Shang Kim 1, Hyung-Sub Kang 1, Shang-Jin Kim 1,* and Nam Soo Kim 1,* 1 College of Veterinary Medicine, Jeonbuk National University, Specialized Campus, Iksan 54596, Korea; [email protected] (H.-R.L.); [email protected] (G.O.A.); [email protected] (D.K.Y.); [email protected] (T.T.); [email protected] (J.-S.K.); [email protected] (H.-S.K.) 2 Hansarang Animal Hospital, Seoul 02880, Korea 3 Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, Sudan University of Science and Technology, P.O. Box 204 Khartoum, Sudan 4 Korea Basic Science Institute Jeonju Center, Jeonju 54896, Korea; [email protected] * Correspondence: [email protected] (S.-J.K.); [email protected] (N.S.K.); Tel.: +82-63-850-0963 (S.-J.K.); +82-63-850-0938 (N.S.K.) These authors contributed equally to this work. † Received: 14 July 2020; Accepted: 11 August 2020; Published: 19 August 2020 Simple Summary: Accurate planning, for corrective surgeries in case of bone cutting, is necessary to obtain a precise coordination of the skeleton and to achieve the owner’s satisfaction. The present experiment displays a simple and cost-eﬀective technique for surgical planning, utilizing a 3-D bone phantom model in a dog with foreleg deformity.

Abstract: 3-D surgical planning for restorative osteotomy is costly and time-consuming because surgeons need to be helped from commercial companies to get 3-D printed bones. However, practitioners can save time and keep the cost to a minimum by utilizing free software and establishing their 3-D printers locally. Surgical planning for the corrective osteotomy of antebrachial growth deformities (AGD) is challenging for several reasons (the nature of the biapical or multiapical conformational abnormalities and lack of a reference value for the specific breed). Pre-operative planning challenges include: a definite description of the position of the center of rotation of angulation (CORA) and proper positioning of the osteotomies applicable to the CORA. In the present study, we demonstrated an accurate and reproducible bone-cutting technique using patient-specific instrumentations (PSI) 3-D technology. The results of the location precision showed that, by using PSIs, the surgeons were able to accurately replicate preoperative resection planning. PSI results also indicate that PSI technology provides a smaller standard deviation than the freehand method. PSI technology performed in the distal radial angular deformity may provide good cutting accuracy. In conclusion, the PSI technology may improve bone-cutting accuracy during corrective osteotomy by providing clinically acceptable margins.

Keywords: 3-D; antebrachial growth deformities; corrective osteotomy; dog; patient-speciﬁc instrumentation; virtual surgical planning

1. Introduction Since the three-dimensional (3-D) fabrication methods developed in 1981 [1,2], this additive manufacturing technology has become possible through the stereo lithography apparatus (SLA) method

Animals 2020, 10, 1445; doi:10.3390/ani10091445 www.mdpi.com/journal/animals Animals 2020, 10, 1445 2 of 13

(in 1984) and fused deposition modeling (FDM) 3-D printing process (in 1988) [3]. In 1992, human body cleft palate was produced using 3-D printing by the SLA method. In 1997, a 3-D printed physical model of a human patient’s joint was used to establish a surgical plan in orthopedic surgery and to improve surgical completion [4]. An unfitted osteotomy can lead to serious iatrogenic translation because of inadequately measured bone deformities [5,6]. In the case of angular limb deformity (ALD) corrective osteotomy, many studies have been conducted using the 3-D technique and RP bone model. In particular, the improvement of the operation time, irradiation time, surgical invasion, surgical accuracy, and patient pain, patient-specific instrumentations’ (PSI) usefulness—such as risk, pre-operative planning, and surgical error reduction—have recently been demonstrated [7–17]. In general, a program that converts computed tomography (CT) data, which is used in many studies, into a 3-D printable file format (stereo-lithography; STL) after bone segmentation and 3-D surgical planning simulation program are expensive and require expertise for operation. Therefore, attempting to request 3-D print production of an affected bone model and patient-specific osteotomy guides from an external company may require more than two weeks’ time, several modifications, and relatively high costs [18–21]. These drawbacks rendered the application of this technique limited in the surgical field in general, and veterinary field in particular; regardless, the technology has advanced [18,21]. Limited information on surgical-planning techniques are reported in veterinary literature [17,20,22–27]. In this study, we employ the PSI for corrective osteotomy using a rapid prototyping (RP) technique. Our technique utilizes in-home facilities, such as 3D-printers and free software packages, that are affordable to many practitioners. The PSI can be applied to joint replacement, joint resurfacing for artificial cartilage implantation, and corrective osteotomy cutting and drilling guides [28–30]. The purpose of this study was to compare the results of the PSI-assisted osteotomy with the freehand osteotomy performed on the three-dimensionally fabricated ghost radial bone models and to evaluate the reproducibility and accuracy of each technique. Also, an in-progress protocol with low cost and simplified process was demonstrated.

2. Materials and Methods All animal procedures were conducted in accordance with the Guide for the Care and Use of Laboratory Animals published by the US National Institute of Health (NIH Publication no. 85-23, revised 1996). The study protocol was reviewed and approved by the Committee on the Care of Laboratory Animal Resources, Jeonbuk National University with an ethical approval number of CBNU2018-0044. The study was conducted at Hansarang Animal Hospital (Seoul, Republic of Korea) and College of Veterinary Medicine, Jeonbuk National University (Iksan, Republic of Korea). To improve accessibility in the veterinary orthopedic ﬁeld, low-cost products were selected for less than $500 (FDM 3-D printer; $350, PLA ﬁlaments; $15, open source free software, etc.).

2.1. Case Presentation and Imaging The simulated bones consisted of the forelimb angular deformity model in a 14-month-old, female Golden Retriever dog weighing 28.4 kg presented with less weight-bearing on the lower left forelimb, restricted flexion and pronation/supination, radial shortening due to premature closure of the epiphyseal growth plates, and pain due to kinetic chain dysfunction (Figure1a,b). Orthogonal radiographs were taken to evaluate the orientation and the site of the maximal radio-ulnar angular deformity (Figure1c,d). CT images (slice thickness 0.7 mm; 120 kV; helical CT Alexion, Toshiba, Japan) were obtained from the distal third of the humerus to the metacarpal bones of both the affected and unaffected legs (Figure2). The a ffected and unaffected side structures of the radius and delineated from CT images of a patient with angular deformity who scheduled for corrective osteotomy. 3-D slicer freeware (3-D Slicer, https://www.slicer.org/; version 4.8.0) was used to convert bone surface image information into a SLT file format. Preoperative planning of the osteotomy was presented by a CAD Animals 2020, 10, 1445 3 of 13 program (3-D Builder; Microsoft windows application, www.microsoft.com) with the SLT images Animalsof the distal2020, 10 radius., x FOR PEER The REVIEW CAD file of the cutting guide renders virtually placed in the affected3 area,of 13 Animals 2020,, 10,, x FOR PEER REVIEW 3 of 13 and cutting planes placed on the virtual 3-D bone models (Figure2). The previously extracted SLT previouslymodels from extracted the antebrachia SLT models were from used the in 3-Dantebrachia printers were by using used special in 3‐D g-codes printers that by using were generatedspecial g‐ previously extracted SLT models from the antebrachia were used in 3‐D printers by using special g‐ codesby a free that software were generated (CURA; https: by a// ultimaker.comfree software /(CURA;software /https://ultimaker.com/software/ultimaker-cura) (Figure3). The experiments ultimaker‐ codes that were generated by a free software (CURA; https://ultimaker.com/software/ ultimaker‐ werecura) organized(Figure 3). usingThe experiments patient-specific were phantom organized models using fabricatedpatient‐specific in-house phantom from themodels PLA fabricated filaments cura) (Figure 3). The experiments were organized using patient‐specific phantom models fabricated inusing‐house FDM from 3-D the printing PLA filaments (Alpha-i3, using Alpha3-D, FDM 3‐ Korea)D printing (Figure (Alpha4). ‐i3, Alpha3‐D, Korea) (Figure 4). in‐house from the PLA filaments using FDM 3‐D printing (Alpha‐i3, Alpha3‐D, Korea) (Figure 4).

Figure 1. The images show the antebrachial growth deformity (AGD)‐affected (left leg) and Figure 1.1. TheThe images images show show the the antebrachial antebrachial growth growth deformity deformity (AGD) (AGD)-a‐affectedﬀected (left (left leg) and contralateral unaffected‐antebrachium (right leg) with the joint‐orientation angles (a,b), and contralateral unaunaffectedﬀected-antebrachium‐antebrachium (right (right leg) leg) with thewith joint-orientation the jointjoint‐orientation angles ( a,anglesb), and orthogonal(a,b), and orthogonal radiographs (c,d). orthogonalradiographs radiographs (c,d). (c,d).

Figure 2. CT from the distal third of the humerus to the metacarpal bones of both the affected (a) and Figure 2. CT from from the distal third of the humerus to the metacarpal bones of both the affected aﬀected ( a) and unaffected leg (b). unaffectedunaﬀected leg ((b).).

Figure 3. Printer for the in‐house fabrication. In this study, the desk‐top fused deposition modeling Figure 3.3. Printer forfor the the in-house in‐house fabrication. fabrication. In In this this study, study, the the desk-top desk‐top fused fused deposition deposition modeling modeling 3-D 3‐D printer was employed for the in‐house fabrication from polylactic acid filaments (a). Before the printer3‐D printer was employedwas employed for the for in-house the in‐house fabrication fabrication from polylacticfrom polylactic acid ﬁlaments acid filaments (a). Before (a). Before the thesis the thesis research work, accuracy checking process for this 3‐D printer was performed using 3‐D researchthesis research work, accuracy work, accuracy checking checking process for process this 3-D for printer this 3 was‐D printer performed was using performed 3-D accuracy-test using 3‐D accuracy‐test tool (b). toolaccuracy (b). ‐test tool (b). Animals 2020, 10, 1445 4 of 13

Animals 20202020,, 1010,, xx FOR PEER REVIEW 44 ofof 1313

Figure 4.4. A G G-code‐‐codecode file ﬁlefile generating process for for the 3-D3‐‐D printingprinting process.process. It It can can be generated from from the the STL image image using the CURA applicationapplication program.program.

2.2. Virtual Virtual Corrective Osteotomy Virtual osteotomyosteotomy was performed (Figure (Figure 55)) alongalong thethethe osteotomyosteotomy planeplane designeddesigned previously,previously, followedfollowed by by correction correction of of thethe the deformity deformity using using thethe the ‘activate’‘activate’ ‘activate’ or ‘deactivate’ or‘deactivate’ ‘deactivate’ object object mode mode toto rotaterotate to rotate and moveand move functionsfunctions functions using using thethe the 3‐‐D 3-D builder builder (Microsoft(Microsoft (Microsoft windows windows freefree free application application program, program, MicrosoftMicrosoft Corporation, Washington, DC,DC, USA).USA). TheThe aaffectedffected radiusradius modelmodel waswas cutcut intointo segmentssegments and the the distal bone segmentsegment waswas repositioned.repositioned. The The plates, PL1” PL1”-PL2’‐‐PL2’ were designed and appropriateappropriate osteotomyosteotomy planesplanes at thethe optimumoptimum cutting points (TJ (TJ-PL2’)(TJ‐‐PL2’) were selected, selected, followedfollowed by by choosing choosing thethe ‘subtract’‘subtract’ functionfunction inin in thethe the edit edit mode mode forfor for plates plates on thethe on osteotomy the osteotomy plane plane thatthat intersectedintersected that intersected thethe affected the a ff radialradialected model. radial Themodel. correction The correction was confirmed was confirmed by measuring by measuring appropriate appropriate angles. angles. For thethe For collinear the collinear realignment,realignment, realignment, we wevirtualized virtualized thethe the opening opening wedge, wedge, closing closing wedge, wedge, neutral neutral wedge, wedge, and and dome dome osteotomy, osteotomy, thenthen then confirmed confirmed our surgical surgical planning based on the the concepts such such as thethe CORA, CORA, multiple multiple osteotomies, osteotomies, anatomical and mechanical axes, angulation correction axis, and the the bisector. We also considered patient factors factors and fixationfixationfixation methodsmethods toto determinedetermine thethe surgicalsurgical plan.plan.

Figure 5. Virtual simulative corrective osteotomy. Surgical simulations were performed in virtual Figure 5. Virtual simulative corrective osteotomy. Surgical simulations were performed in virtual realityreality toto predictpredict postoperativepostoperative conditions.conditions. Note Note thethe changechange inin thethe axis before and after thethe virtualvirtual correctivecorrective osteotomy. The figure ﬁgurefigure on the the left left ( (a,,cc)) showsshows penetrated images images and on the the right right ( (b,,d)) are 33-D‐‐D rendering rendering images.images.

2.3. PSI PSI Design forfor the the Distal Radial Surface Two PSIsPSIs designed designed for forfor each each plane plane cuts cuts on theon radius.thethe radius.radius. Each Each PSI was PSI created was created to fit the toto uniquefitfit thethe unique surface prominencessurfacesurface prominences and depressions and depressions of the osteotomy of thethe osteotomy site of the sitesite bone of thethe surface bone surface andsurface establishes and establishes a flat surface a flatflat surfacerepresentingsurface representingrepresenting the target thethe cutting targettarget planecutting (Figure plane6 (Figure(Figure). Each 6). PSI Each was designedPSI was designed with guide with holes guide for holes 1.2-mm forfor 1.2K-wires‐‐mm thatK‐‐wires were thatthat used were for temporarily used forfor temporarilytemporarily fixing the PSI fixingfixing on thethethe bone PSI on during thethe bone osteotomy during and osteotomy could also and be couldused as also predrilling be used holes as predrilling for plate and holes screw forfor fixation. plate and After screwscrew the PSIfixation.fixation. design After was approved,thethe PSI design PSIs were was approved, PSIs were manufactured inin‐‐house using RP technologytechnology with a desktop fusedfused filamentfilament fabricationfabrication 3‐‐D printer (Alpha(Alpha‐‐i3,i3, Alpha3‐‐D, Seoul, Korea) inin a PLA material. Animals 2020, 10, 1445 5 of 13 manufactured in-house using RP technology with a desktop fused filament fabrication 3-D printer (Alpha-i3, Alpha3-D, Seoul, Korea) in a PLA material. Animals 2020, 10, x FOR PEER REVIEW 5 of 13

Figure 6. Final designs of patient patient-speciﬁc‐specific instrumentation (PSI) models were demonstrated through 33-D‐D rendering images ( a,,b), 3 3-D‐D printed PSIs ( (cc),), and and the the PSIs PSIs positioning positioning on on a a rapid rapid prototyping prototyping (RP) (RP) bone model precisely ( d–f). The The patient patient-speciﬁc‐specific cutting cutting guides added a drill guide for for the the bone plate and screw placement. The PSIs attached on the RP bone model in in-situ‐situ ( d–f).

2.4. In In-House‐House Fabrication Fabrication Ten real-sizedreal‐sized RP bone models were manufactured in in-house‐house using the FDM 3 3-D‐D printer and a phantom bone bone model model was was fabricated. fabricated. RP RP bone bone models models were were wrapped wrapped by cotton by cotton rolls rolls followed followed by self by‐ adhesiveself-adhesive elastic elastic tapes tapes (Coban, (Coban, 3M, 3M,St. Paul, St. Paul, MN, MN, USA) USA) (Figure (Figure 7). 7).

Figure 7. RapidRapid prototyping prototyping bone bone models were fabricated with the polylactic acid material using the fusedfused deposition modelingmodeling method method (above, (above,a ,ab,b)) and and then then the the phantom phantom bone bone models models were were fabricated fabricated for forthis this study study (below, (below,c). c).

The PSIs were provided with 1.2 mm mm-diameter‐diameter pin guides for temporary fastening to the radial bones using K K-wires‐wires or bone forceps. The The needles needles were were used used during during surgery surgery to find ﬁnd the PSI guidance locationlocation as set in the preoperative plan.

2.5. Rehearsal Rehearsal Surgery Surgery on on the the Phantom Bone Models with PSI Five operators individually performed performed two two cuts cuts using using PSI and freehand on the phantom bone models. Before Before sawing, sawing, each each operator operator was was directed directed to to position the two PSIs without an instrument and fix fix them on the the phantom phantom radial radial bone bone model model using using the the bone bone holding holding forceps forceps or or K K-wires‐wires to to prevent prevent movement. After After sawing, sawing, each each operator operator was was directed directed to to take o ff ff the bone holding forceps. The bone model waswas fixedfixed using using a a steel steel vise vise (Multi-Angle (Multi‐Angle Base Base Vise Vise 83-069, 83‐069, with with a multi-angle a multi‐angle rotating rotating ball jointball jointsystem) system) to a proper to a proper position position for the for simulation the simulation (Figure 8(Figure). To avoid 8). To errors avoid while errors sawing, while the sawing, order was the ordergiven was to the given target to plane the target as precisely plane as as precisely possible. as For possible. the freehand For the cutting, freehand a craniomedial cutting, a craniomedial approach to approach to the distal radius model was completed. An osteotomy was performed by an oscillating saw 25 mm apart from the carpal joint margin in parallel (Figure 9). A second osteotomy was ordered at a fixed angle of 25 degrees relative to the first osteotomy at the corrective angle. The positions and angles for the cutting planes were the same as the surgical planning conditions given in the PSI designed on the CAD software. Before freehand cutting, each operator was asked to decide and place Animals 2020, 10, 1445 6 of 13 the distal radius model was completed. An osteotomy was performed by an oscillating saw 25 mm apart from the carpal joint margin in parallel (Figure9). A second osteotomy was ordered at a fixed angle of 25 degrees relative to the first osteotomy at the corrective angle. The positions and angles Animals 2020, 10, x FOR PEER REVIEW 6 of 13 for the cutting planes were the same as the surgical planning conditions given in the PSI designed on kthe‐wires CAD as software. a guidance Before navigator, freehand and cutting, the sawing each was operator done wasby hand asked with to decide an oscillating and place saw k-wires without as a cutting guidance guide. navigator, The total and time the sawingfor the bone was donecutting by was hand defined with an by oscillating the time spent saw withoutfrom the a point cutting of exposingguide. The the total bone time‐cutting for the site bone until cutting the end was of defined bone cutting. by the timeIn the spent freehand from thegroup, point the of total exposing time includedthe bone-cutting the arrangement site until time the end of placement of bone cutting. of the navigation In the freehand K‐wire group, and intraoperative the total time control included of the arrangementcorrect osteotomy time of angle placement under of ruler the navigationmeasurement. K-wire In andthe PSI intraoperative group, the controltotal time of the included correct positioningosteotomy angle and temporarily under ruler fixing measurement. the PSI on In the the model PSI group, surface the and total then time finish included the sawing positioning under andPSI guidance.temporarily fixing the PSI on the model surface and then finish the sawing under PSI guidance.

Figure 8. TheThe position position and and angles angles for for the the cutting cutting procedures. procedures. Prior Prior to tothe the ex‐ ex-vivovivo osteotomy, osteotomy, each each of theof the five five operators operators were were directed directed to to position position the the phantom phantom bone bone model model to to a a vise vise ( a,,b).). The surgical planning conditions for the freehand method were the same as the patient-specificpatient‐specific instrumentation (PSI) methodmethod ( c(c).). Positioning Positioning PSI PSI was was ordered ordered without without positioning positioning aids, aids, but wasbut was only only fixed fixed on the on rapid the rapidprototyping prototyping model model using using the bone-holding the bone‐holding forceps forceps or K-wires or K‐ forwires temporary for temporary fixation fixation (d). (d).

Figure 9. RulersRulers were were attached attached to tothe the cranial, cranial, caudal, caudal, medial, medial, and and lateral lateral bone bone model model surfaces. surfaces. The orangeThe orange and yellow and yellow plates plates show show the osteotomy the osteotomy target target plane. plane. The black The blackand white and whitestriped striped bar is made bar is 1made mm 1against mm against each space each to space indicate to indicate the distance the distance from the from edge the of edge the ofjoint the surface. joint surface.

2.6. Accuracy Accuracy Evaluation Evaluation PSI technologytechnology was was used used to evaluateto evaluate 20 intersection 20 intersection data sets data for sets a precise for a cut precise using twocut parameters.using two parameters.The accurate The location accurate and location angulation and were angulation used to evaluatewere used the to geometrical evaluate the accuracy geometrical of the accuracy cut planes. of theThe cut bone planes. phantom The bone model phantom and PSI model technology and PSI were technology performed were to performed assess the etoffect assess of the the variables effect of thebetween variables distal between and proximal distal boneand cutproximal planes bone and amongcut planes a group and of among operators. a group The variableof operators. ‘operator’ The wasvariable considered ‘operator’ as a was random considered effect. The as anglea random of cutting effect. planes The andangle positional of cutting accuracy planes were and consideredpositional accuracytwo numerical were considered responses of two the numerical model. Statistical responses analysis of the was model. performed Statistical by analysis using Fisher’s was performed exact test byand using the statistical Fisher’s exact differences test and for the both statistical the location differences and angle for using both the were location investigated and angle their using logarithms were investigated their logarithms to base 10. The p‐value of less than 0.05 was considered statistically significant. The post‐hoc Tukey’s tests were conducted to determine whether the target variable was different in terms of response variables and if the effect of the variable ‘target plane’ was significant (p < 0.05).

Animals 2020, 10, 1445 7 of 13 to base 10. The p-value of less than 0.05 was considered statistically significant. The post-hoc Tukey’s tests were conducted to determine whether the target variable was different in terms of response Animalsvariables 2020 and, 10, x if FOR the PEER effect REVIEW of the variable ‘target plane’ was significant (p < 0.05). 7 of 13

3. Results Results The imagesimages revealed revealed abnormal abnormal lateral lateral orientation orientation at the at distal the distal part of part the radiusof the and radius ulna, and proximal ulna, proximalto the carpal to the joint. carpal Craniocaudal joint. Craniocaudal and mediolateral and mediolateral radiographic radiographic projections projections showed a multiplaneshowed a multiplaneantebrachial antebrachial bone deformity bone (Figure deformity1c,d). (Figure 1c,d). Twenty cut planes (4 out of the 5 operators) were used for estimation of the cutting performance with PSIPSI procedure procedure (Figure (Figure 10 ).10). The The proper proper position position of the of cut the planes cut planes and the and obtained the obtained surgical surgical margins marginswere subjected were subjected to notable to di ffnotableerences differences regarding theregarding average the and average 95% confidence and 95% interval confidence (CI) betweeninterval (CI)the four between target the planes. four target The location planes. precisionThe location of the precision PSI-assisted of the cutting PSI‐assisted distance cutting from distance the target from on the medial and lateral radius (mean 0.2 mm, 95% CI [ 0.1016, 0.5016] and 0.2 mm, 95% CI [ 0.1016, the target on the medial and lateral radius (mean 0.2 mm,− 95% CI [−0.1016, 0.5016] and 0.2 mm,− 95% CI0.5016], [−0.1016, respectively; 0.5016], respectively; both p-values both< 0.0001)p‐values were < 0.0001) significantly were significantly different from different that from of the that freehand of the freehandtechnique technique (average 4.1 (average mm, 95% 4.1 CI mm, [2.774, 95% 5.426], CI [2.774,p = 0.0270 5.426], and p 4.4= 0.0270 mm 95% and CI 4.4 [2.516, mm 6.284],95% CIp [2.516,> 0.10, 6.284],respectively). p > 0.10, The respectively). freehand marginal The freehand point marginal achieved point in the achieved lateral (average in the lateral 4.4 mm, (average 95% CI 4.4 [2.516, mm, 6.284]) were significantly higher than that achieved in the PSI (average 0.2 mm, 95% CI [ 0.1016, 95% CI [2.516, 6.284]) were significantly higher than that achieved in the PSI (average 0.2 mm,− 95% CI0.5016], [−0.1016,p < 0.0001),0.5016], asp < shown 0.0001), in as Table shown1. in Table 1.

Figure 10.10. SimulativeSimulative osteotomy osteotomy result result on on phantom phantom bone bone models. models. Patient-speciﬁc Patient‐specific instrumentation instrumentation (PSI) (PSI)and freehand and freehand (FH) marked(FH) marked rapid rapid prototyping prototyping bone models bone models are the are result the of result the osteotomy of the osteotomy using the using PSI theand PSI freehand, and freehand, respectively. respectively. This picture This was takenpicture after was the taken ex-vivo after osteotomies the ex‐vivo were osteotomies performed onwere the performedphantom bone on the models phantom and thebone outer models materials and the were outer removed. materials were removed.

Table 1. Distance (mm) from the target plane to the cut plane: freehand (FH) vs. patient-speciﬁc Table 1. Distance (mm) from the target plane to the cut plane: freehand (FH) vs. patient‐specific instrumentations (PSI). instrumentations (PSI)

CranialCranial 1Caudal Caudal 1Medial Medial 1Lateral Lateral 1 CranialCranial 2 CaudalCaudal 2 MedialMedial 2 LateralLateral 2

Target1 01 01 01 0 02 02 02 0 2 FH 1 5 5 5 5 5 5 5 5 Target 0 0 0 0 0 0 0 0 FH 2 2 3 1 10 4 2 4 7 FHFH 1 35 55 25 75 3 45 15 45 5 5 FHFH 2 42 13 01 110 3 24 52 44 2 7 FHFH 3 55 52 57 53 1 24 31 54 3 5 FHPSI 4 11 00 01 03 0 02 05 04 0 2 PSI 2 0 0 0 0 0 0 0 0 FHPSI 5 35 05 05 01 0 12 13 15 1 3 PSIPSI 1 40 00 00 00 0 10 10 10 1 0 PSIPSI 2 50 00 00 00 0 0 00 00 0 0 t-testPSI FH 3 vs. PSI 0.0150 0 0.034 0.0340 0.0340 0.0461 0.0221 0.0001 0.0081 PSI 4 0 0 0 0 1 1 1 1 ThePSI maximum 5 distance0 between0 the achieved0 marginal0 point0 and the planned0 marginal0 point0 was foundt‐test inFH the vs. lateral PSI area0.015 of the0.034 marginal point0.034 (3 and0.034 0 mm for junior0.046 and senior0.022 surgeons,0.000 respectively).0.008 The 2-mm desired safe margin is showed by the solid line ‘target’ on Figure 11, (a) p < 0.05 compared The maximum distance between the achieved marginal point and the planned marginal point was found in the lateral area of the marginal point (3 and 0 mm for junior and senior surgeons, respectively). The 2‐mm desired safe margin is showed by the solid line ‘target’ on Figure 11, (a) p < 0.05 compared with freehand; and (b) p < 0.05 compared with PSI. The angulation of the cut planes was subjected to insignificant variations between the target planes. The cutting angle error from the target cutting angle between the distal and proximal cut planes in the freehand group (mean 8.558 Animals 2020, 10, 1445 8 of 13

withAnimals freehand; 2020, 10, x and FOR (b)PEERp

Figure 11. Distance (mm) from the target plane to the cut plane: freehand (FH) versus patient speciﬁcspecific Figure 11. Distance (mm) from the target plane to the cut plane: freehand (FH) versus patient specific instrumentinstrument (PSI).(PSI). The numbers on thethe centercenter toto thethe 12 o’clock direction areare thethe indicatedindicated distancesdistances inin instrument (PSI). The numbers on the center to the 12 o’clock direction are the indicated distances in millimeters from the cutting target position.position. The PSI group (left) and the FH group (right) side werewere millimeters from the cutting target position. The PSI group (left) and the FH group (right) side were placed.placed. The results are shown separatelyseparately byby dividingdividing thethe cut-planescut‐planes 11 andand 22 inin eacheach texttext box.box. placed. The results are shown separately by dividing the cut‐planes 1 and 2 in each text box. The mean time time consumed consumed for for cutting cutting to tocomplete complete two two planes planes in each in each phantom phantom model model was 7.9 was ± The mean time consumed for cutting to complete two planes in each phantom model was 7.9 ± 7.94.8 min4.8 and min 1.6and ± 1.1 1.6 min1.1 for min the forfreehand the freehand and PSI, and respectively PSI, respectively (Figure 12). (Figure Measurement 12). Measurement point was 4.8 ±min and 1.6 ± 1.1 min± for the freehand and PSI, respectively (Figure 12). Measurement point was pointset on was the cranial, set on the caudal, cranial, medial, caudal, and medial, lateral surfaces and lateral of the surfaces rapid ofprototyping the rapid prototypingphantom bone phantom model. set on the cranial, caudal, medial, and lateral surfaces of the rapid prototyping phantom bone model. boneIn the model. PSI group, In the accuracy PSI group, test accuracyresults showed test results less than showed 1 mm less distance than 1 from mm distance the target from plane. the On target the In the PSI group, accuracy test results showed less than 1 mm distance from the target plane. On the plane.other hand, On the the other freehand hand, method the freehand group method results groupshowed results up to showed 11 mm of up error to 11 from mm ofthe error target from plane. the other hand, the freehand method group results showed up to 11 mm of error from the target plane. targetThe PSI plane. manner The required PSI manner significantly required less signiﬁcantly time than lessthe freehand time than models the freehand (p < 0.0001). models The (p operating< 0.0001). The PSI manner required significantly less time than the freehand models (p < 0.0001). The operating Thetime operating was 6.9 min time (range, was 5.6–7.9 6.9 min min) (range, in the 5.6–7.9 senior min) surgeons in the and senior 8.1 min surgeons (range, and 5.3–12.4 8.1 min min) (range, in the time was 6.9 min (range, 5.6–7.9 min) in the senior surgeons and 8.1 min (range, 5.3–12.4 min) in the 5.3–12.4junior surgeons min) in (Figure the junior 13), surgeons in which (Figure the operation 13), in time which consumption the operation of the time FH consumption group appears of the higher FH junior surgeons (Figure 13), in which the operation time consumption of the FH group appears higher groupthan the appears PSI user higher group. than The the box PSI plot user of group. angular The errors box plotis shown of angular in Figure errors 14, is where shown the in correction Figure 14, than the PSI user group. The box plot of angular errors is shown in Figure 14, where the correction whereangle error the correction score of the angle FH error group score appears of the higher FH group than appearsthe PSI user higher group. than the PSI user group. angle error score of the FH group appears higher than the PSI user group.

Figure 12.12. Distance (mm) from the target planeplane toto thethe cutcut plane:plane: freehandfreehand versusversus patient-speciﬁcpatient‐specific Figure 12. Distance (mm) from the target plane to the cut plane: freehand versus patient‐specific instrumentationinstrumentation (PSI). The measurement point was setset onon thethe cranial,cranial, caudal,caudal, medial,medial, andand laterallateral instrumentation (PSI). The measurement point was set on the cranial, caudal, medial, and lateral surfacessurfaces ofof thethe rapid prototyping phantomphantom bonebone model.model. In the PSI group, accuracy test results showed surfaces of the rapid prototyping phantom bone model. In the PSI group, accuracy test results showed lessless thanthan 11 mm distance fromfrom thethe targettarget plane.plane. On the other hand, the freehand method group results less than 1 mm distance from the target plane. On the other hand, the freehand method group results showedshowed upup toto 1111 mmmm ofof errorerror fromfrom thethe targettarget plane.plane. showed up to 11 mm of error from the target plane. Animals 2020, 10, x 1445 FOR PEER REVIEW 9 9of of 13 13 Animals 2020, 10, x FOR PEER REVIEW 9 of 13

Figure 13. Boxplot displaying the time consumption for the cutting procedure after applying the two FigureFigure 13. BoxplotBoxplot displaying displaying the the time time consumption consumption for for the the cutting cutting procedure procedure after after applying applying the the two two different methods: freehand (FH) versus patient‐specific instrumentation (PSI). *** p < 0.001, t‐test vs. differentdiﬀerent methods: methods: freehand freehand (FH) (FH) versus versus patient patient-speciﬁc‐specific instrumentation instrumentation (PSI). (PSI). *** *** p

Figure 14. Boxplot displaying displaying the the correction correction angle angle error error of of the cutting procedure after applying the Figure 14. Boxplot displaying the correction angle error of the cutting procedure after applying the twotwo didifferentfferent methods:methods: freehandfreehand (FH) (FH) versus versus patient-specific patient‐specific instrumentation instrumentation (PSI). (PSI). *** ***p < p0.001, < 0.001,t-test t‐ two different methods: freehand (FH) versus patient‐specific instrumentation (PSI). *** p < 0.001, t‐ testvs. FH. vs. FH. test vs. FH. 4. Discussion 4. Discussion 4. Discussion Since over- and under-correction could lead to the loss of restoration of range motion, the accuracy Since over‐ and under‐correction could lead to the loss of restoration of range motion, the of pre-Since and over post-operative‐ and under reconstruction‐correction could is critical lead [ 31to]. the Hence, loss computerizedof restoration 3-D of range comparisons motion, of the the accuracy of pre‐ and post‐operative reconstruction is critical [31]. Hence, computerized 3‐D accuracycontralateral of bonespre‐ and are usefulpost‐operative for preoperative reconstruction planning ofis thecritical corrective [31]. osteotomyHence, computerized in the complicated 3‐D comparisons of the contralateral bones are useful for preoperative planning of the corrective comparisonsangular deformities of the andcontralateral complex malunions.bones are useful Some technologies,for preoperative such planning as navigation of the systems corrective and osteotomy in the complicated angular deformities and complex malunions. Some technologies, such osteotomyPSIs, have assistedin the complicated surgeons to angular perform deformities as accurate and as planned complex in malunions. human orthopedic Some technologies, medicine [32 such,33]. as navigation systems and PSIs, have assisted surgeons to perform as accurate as planned in human asIn navigation particular, systems PSIs are and becoming PSIs, have more assisted popular surgeons because to they perform are easieras accurate to handle as planned than navigation in human orthopedic medicine [32,33]. In particular, PSIs are becoming more popular because they are easier orthopedicsystems and medicine are more [32,33]. precise In than particular, free hand PSIs in vitroare becoming study [34 ].more popular because they are easier to handle than navigation systems and are more precise than free hand in vitro study [34]. to handleTo compare than navigation the traditional systems CORA and measurement are more precise orthogonal than free radiographs hand in vitro with study a CT-defined [34]. wedge, To compare the traditional CORA measurement orthogonal radiographs with a CT‐defined we utilizedTo compare radiographs the traditional of both models.CORA measurement Fixation of elbow orthogonal of the model radiographs rendered with replication a CT‐defined of the wedge, we utilized radiographs of both models. Fixation of elbow of the model rendered replication wedge,dog’s limb we utilized difficult. radiographs Regardless, of two both methods models. of Fixation measurement of elbow yielded of the significantly model rendered different replication results of the dog’s limb difficult. Regardless, two methods of measurement yielded significantly different ofwith the terms dog’s tolimb the difficult. wedge angle Regardless, and orientation. two methods The of use measurement of 3-D CT reconstruction,yielded significantly to identify different the results with terms to the wedge angle and orientation. The use of 3‐D CT reconstruction, to identify resultstrue orientation with terms of to joint the surfaceswedge angle to apply and orientation. the CORA approach, The use of has 3‐D not CT been reconstruction, previously to described identify the true orientation of joint surfaces to apply the CORA approach, has not been previously described thein animals. true orientation of joint surfaces to apply the CORA approach, has not been previously described in animals. in animals.Meola et al. performed CT scans to assess radial torsion in the presence of procurvatum and Meola et al. performed CT scans to assess radial torsion in the presence of procurvatum and valgusMeola deformity et al. performed in dogs [35 ].CT CT scans data to are assess being radial extensively torsion used in the in human presence studies of procurvatum [36]. To provide and valgus deformity in dogs [35]. CT data are being extensively used in human studies [36]. To provide valgusguidance deformity for correction, in dogs una[35].ff ectedCT data opposite are being 3-D extensively CT data should used in be human collected studies to serve [36]. as To reference provide guidance for correction, unaffected opposite 3‐D CT data should be collected to serve as reference guidancedata. In orthopedic for correction, surgery, unaffected a similar opposite technique 3‐D toCT our data method should has be beencollected described, to serve but as insteadreference of data. In orthopedic surgery, a similar technique to our method has been described, but instead of data.estimating In orthopedic a normal surgery, for the curvature a similar oftechnique the bone to from our themethod joint has surface, been the described, contralateral but instead limb was of estimating a normal for the curvature of the bone from the joint surface, the contralateral limb was estimatingused as a guide a normal [37]. for However, the curvature one of theof the drawbacks bone from of thisthe techniquejoint surface, is that the the contralateral contralateral limb limb was is used as a guide [37]. However, one of the drawbacks of this technique is that the contralateral limb usedalso a asffected a guide by deformity,[37]. However, this method one of the may drawbacks fail to replicate of this the technique normal anatomy.is that the contralateral limb is also affected by deformity, this method may fail to replicate the normal anatomy. is alsoFox affected et al. haveby deformity, described this the method mean medial may fail proximal to replicate radial the angle normal the anatomy. mean lateral distal radial Fox et al. have described the mean medial proximal radial angle the mean lateral distal radial angleFox as 85et al.and have of 87 described, respectively, the mean in the medial frontal proximal plane [27 radial]. 4.88 anglewas the calculatedmean lateral mean distal torsion radial in angle as 85°◦ and of 87°,◦ respectively, in the frontal plane [27]. 4.88°◦ was the calculated mean torsion angle as 85° and of 87°, respectively, in the frontal plane [27]. 4.88° was the calculated mean torsion Animals 2020, 10, 1445 10 of 13 the transverse plane in three dogs [35]. However, these data were based on radiographs calculations and have not been determined from CT reconstructions. Additionally, these data were obtained from medium-to-large, non-chondrodystrophic dogs, and as observed, these angles are likely to vary among breed [27]. Studies using 3-D CT to determine the lateral and cranio-caudal planes accurately and the degree of torsion are useful to guide the future computer-assisted surgeries for ALD. In one study that applied a two-level corrective osteotomy, just 44% of surgical cases were adjusted in both the frontal and sagittal planes [22]. Therefore, the authors pursued a one-level amendment in this case. To perform a single closing wedge osteotomy accurately, we brought a 3-D CT scan, virtual rehearsal surgery with 3-D Builder, a free software into surgical planning protocol. According to our knowledge, the use of this free 3-D design application to simulate a proposed surgery has not been previously published in veterinary surgery. This data was subsequently used to generate a stereolithographic image in plastic which could be handled by the surgeon in rehearsal surgeries and in the operating room. This guaranteed the accuracy of the intra-operative osteotomy as the fragments were aligned to the same angulation as the surgical plan that allowed fixation of plates to be performed precisely. The study attempted a surgical protocol that was simple to deploy in veterinary surgery and could be run at a low cost. That is why we had to plan a wedge technology with a straight oscillating saw blade rather than choosing to use a radial or domed saw blade. This dog’s highly dynamic character would require an additional orthogonal directional bone plate placement. This study showed good precision while using the PSI procedure during simulated osteotomy of the radial bone angular deformity. Osteotomy angulation in the distal and proximal plane assessed in articles of the ISO1101 location parameter indicated how PSI is reliable in the operating room to replicate a preoperative cutting plan on a distal radius with clinical accuracy [38]. Our results agree with those of Oka et al. [39], which found average residual errors of simulated osteotomy using patient-specific guides of less than 1◦ and 1 mm. Investigations using PSI technology had already described promising clinical outcomes. However, their evaluation was only based on intraoperative plane images using image intensifiers. Moreover, the amount of correction and the demographic data of the patients were not exposed. The presented results revealed that the PSI cutting with regard to the location and surgical angles is quite precise. The data presented in this study could be beneficial for the quantitative comparison of various PSI design processes for bone-cutting within the end of the long bone. The presented results did not suggest any notable difference between experienced and inexperienced surgeons using PSI technology with regard to the location accuracy and cutting angles achieved. It appears that the PSI technology may be ready to use by experienced as well as inexperienced digital-aged surgeons. Results with regard to the location accuracy showed that PSIs enabled surgeons to repeat preoperative cutting planning with good accuracy (Figures3–5). Otherwise, the value added by the PSI technology in improving bone-cutting accuracy was similar to that of the planned osteotomy target points and planes. The results regarding the obtained surgical margins (Figures3–6) suggest that PSI technology tended to provide a smaller standard deviation than freehand. Otherwise, the manual cutting errors were minimum with the PSI technology compared to those with the freehand method. Further research should be carried out to verify the results observed in this study. The operation time measured was about 4.8 min bone cutting time during the phantom bone surgery using PSI, similar to the cadaveric long bone resection surgery by Sarah et al. [40]; moreover, compared to the previous report [40]. This study confirmed that PSI technology save time for surgeons compared with other techniques—i.e., in less than 10 min with PSI versus up to 16 min in their study. This can be interpreted by the predefined optimal location of the PSI on the bone surface, which serves as an intuitive and natural transfer of the surgical plan in comparison with the time-consuming manual image-to-patient enrollment phase of the procedure (Figures3–8). Given the time-consuming factors—such as the presence of muscles and nerves, bleeding, patient movements, etc.—further in vivo research will be performed to verify the results observed here. Animals 2020, 10, 1445 11 of 13

5. Conclusions It was demonstrated that using PSI for simulated 3-D bone cuts of the distal radial angular deformity provides an accurate cutting. This study also evaluated PSI technologies quantitatively in their proper location and obtained surgical margins during simulated bone cuts of the deformed radii. In-vivo, ergonomic studies may be performed here in terms of accuracy, reproducibility, and time-consumption. In total, the PSI technology may improve bone-cutting accuracy during corrective osteotomy by oﬀering clinically acceptable margin. Accordingly, practitioners and clinicians can beneﬁt of this cheap and accurate technology to build a 3-D simulated preoperative bones for surgical planning which can be done inside the clinic without outside assistance.

Author Contributions: Conceptualization, N.S.K., H.-S.K., and S.-J.K.; Methodology, H.-R.L., G.O.A., and T.T.; Software, H.-R.L., S.-J.L., and G.O.A.; Formal analysis, D.K.Y., S.-J.L., and S.-J.K.; Data curation, D.K.Y. and T.T.; Writing—original draft preparation, H.-R.L., G.O.A., and S.-J.K.; Project administration, N.S.K., H.-S.K., and J.-S.K.; Funding acquisition, S.-J.K. and H.-S.K. All authors have revised and agreed to the final version of the manuscript. Funding: This research was supported by the Ministry of Science and Technology (NRF-2018R1A2B6003332 and NRF-2018R1D1A3B07049191), South Korea. This study was also partially financed by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry (IPET) via Agriculture, Food and Rural Affairs Convergence Technologies Program for Educating Creative Global Leader, Ministry of Agriculture, Food and Rural Affairs (MAFRA; 320005-4). Acknowledgments: The authors would like to thank the staff of Hansarang Veterinary Clinic, Seoul, Korea for their technical and clinical assistance. Conflicts of Interest: The authors declare no conflict of interest.

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