Accuracy of virtual surgical planning and custom three-dimensionally printed osteotomy and reduction guides for acute uni- and biapical correction of antebrachial deformities in dogs

Evaluation of 3D-printed patient-specific guides to facilitate fluoroscopic-assisted Kirschner wire stabilization of simulated capital physeal fractures in 3D-printed dog femur models

OBJECTIVE

To compare the efficiency and accuracy of freehand and three-dimensionally printed (3DP) guide-facilitated fluoroscopic-assisted Kirschner wire placement in the femoral capitis performed by novice and experienced surgeons.

SAMPLE POPULATION

3DP models of five skeletally immature dog femurs were replicated.

METHODS

Virtual surgical planning was done to position three parallel, virtual Kirschner wires inserted from the lateral subtrochanteric surface of the femur, coursing proximomedially through the femoral neck to engage the central capitis without penetrating the subchondral bone. Patient-specific guides were designed and 3DP to facilitate optimal Kirschner wire placement in each femoral model. Four faculty surgeons and four surgery residents performed freehand fluoroscopic-assisted wire placement in the femoral models. Wire placement was repeated ≥1 month later using the 3DP guides. Surgical time, number of times wires were redirected, number of fluoroscopy images acquired and Likert scores from the participants were recorded. Post-procedural CTs of the femur models were used to assess wire placement by 3D analysis.

RESULTS

The number of fluoroscopy images was greater (p < .001) and procedure time was longer (p < .001) for freehand applications, while Likert scores were greater (p < .001) for 3DP-guide applications. Wire placement was more accurate with 3DP guides. Subchondral bone penetration occurred more frequently during freehand applications (p < .01).

CONCLUSION

3DP patient-specific guides resulted in faster, simpler, and more accurate Kirschner wire placement than freehand placement for both novice and experienced surgeons. Further cadaveric and clinical studies are warranted to evaluate the utility of 3DP patient-specific guides to facilitate minimally invasive fluoroscopic-assisted femoral capital physeal fracture stabilization in dogs.

Three-dimensional automated measurements of femoral angles for the preoperative planning in dogs with patellar luxation

Objectives

To report the surgical outcomes of treating patellar luxation (PL) in dogs with surgical planning based on three-dimensional (3D) automated measurement of femoral angles.

Study design

Multicenter retrospective study.

Methods

Forty-one dogs with PL underwent preoperative computed tomography (CT). Three-dimensional femur models were exported as stereolithographic files, and imported into computer-aided design (CAD) software where 3D measurements were performed. The anatomical laterodistal femoral (aLDFA), femoral neck (FNA), and femoral torsion (FTA) angles were recorded. Surgical records, complications, radiographic femoral postoperative alignment, preoperative and postoperative lameness evaluation, and patellar position were reviewed. The success of the surgical outcome was based on the presence of normal patellar tracking at the last clinical recheck.

Results

Forty-seven limbs were included; 46% of the cases (22/47) were affected by grade 3 PL. Mean (±SD) 3D aLDFA, FNA, and FTA measurements were 101.4° (±3.6), 132.5° (±2.6), and 17.6° (±4.3) in dogs with medial patellar luxation (MPL) and 89.3° (±7.6), 134.8° (±2.9), 36.9° (±5.3) with lateral patellar luxation (LPL), respectively. Based on the 3D preoperative planning, corrective osteotomies were performed in 34 of 47 cases. The mean radiographic follow-up was 4.7 months. At the final follow-up, PL was successfully treated in 45 of 47 cases. Patella reluxated in five cases. In three of five cases, the 3D automated plan was not followed by the surgeon.

Discussion

Surgical treatment of PL based on 3D femoral measurements successfully corrected PL in 45 of 47 cases (96%). This is the first study reporting the use of 3D automated femoral angle measurement in clinical cases affected by PL.

Three-dimensionally printed osteotomy and reaming guides for correction of a multiplanar femoral deformity stabilized with an interlocking nail in a dog

OBJECTIVE

To describe the use of virtual surgical planning (VSP) and three-dimensionally (3D) printed surgical guides for corrective osteotomies stabilized with an interlocking nail in a dog with a multiplanar femoral deformity.

STUDY DESIGN

Case report.

ANIMALS

An 8-year-old male neutered mixed breed dog weighing 44 kg.

METHODS

A dog was presented for a right grade 3 lateral patellar luxation secondary to a multiplanar femoral deformity due to a suspected femoral malunion. A computed tomography (CT) scan was obtained to create virtual femoral models. Corrective osteotomies were simulated with VSP. Custom osteotomy guides and reaming guides were designed to facilitate the correction and the placement of an interlocking nail. The preoperative femoral model, virtually aligned femoral model, custom osteotomy guides, and reaming guides were 3D printed, sterilized, and utilized intraoperatively. A CT scan was performed postoperatively to assess femoral length and alignment.

RESULTS

Custom osteotomy and reaming guides were used as intended by the VSP. Postoperative femoral length as well as frontal, sagittal, and axial plane alignment were within 0.7 mm, 2.2°, 0.5°, and 1.6°, respectively, of the virtually planned femoral model. Two months postoperatively, the dog was sound on visual gait examination, and the patella tracked in the trochlear groove throughout stifle range of motion and was unable to be manually luxated. Radiographs obtained 2 months postoperatively revealed static femoral alignment and implants. Both osteotomies were discernable with callus bridging.

CONCLUSION

Virtual surgical planning and custom osteotomy and reaming guides facilitated complex femoral corrective osteotomies and interlocking nail placement.

Surgical correction of pes varus deformity in dachshunds using three-dimensional-printed patient-specific guide system: nine tibiae in seven cases (2018-2022)

OBJECTIVES

To describe the use of a three-dimensional-printed patient-specific guide system for the treatment of distal tibial varus deformity in Dachshunds and retrospectively report the clinical and radiographic outcome.

MATERIALS AND METHODS

Pes varus deformity in nine limbs of seven dachshunds was treated with corrective osteotomy using a three-dimensional-printed patient-specific guide system. Data from computed tomography were processed to obtain virtual 3D-models of the tibias, which were used for computer-aided design-based surgical planning, three-dimensional-printed patient-specific guide system design and evaluation of planned versus achieved tibial correction. Clinical outcomes were evaluated by lameness score and post-operative owner-reported questionnaire at a minimum of 15 months.

RESULTS

The gait abnormality resolved in all limbs. The osteotomy healed uneventfully in eight tibiae. Implant failure occurred in one tibia but was successfully revised. There was good correlation between planned and achieved deformity correction, with mean translational error <1 mm in all planes, and mean angulation correction error <2° in all planes.

CLINICAL SIGNIFICANCE

A 3D-printed patient-specific osteotomy and reduction guide system facilitates the accurate correction of tibial pes varus deformity with very good clinical outcomes. Opening osteotomy, stabilised with orthogonal locking plates and without the application of bone graft led to satisfactory bone healing in all cases.

Efficacy of virtual surgical planning and a three-dimensional-printed, patient-specific reduction system to facilitate alignment of diaphyseal tibial fractures stabilized by minimally invasive plate osteosynthesis in dogs: A prospective clinical study

OBJECTIVE

To evaluate the efficacy of a three-dimensional (3D)-printed, patient-specific reduction system for aligning diaphyseal tibial fractures stabilized using minimally invasive plate osteosynthesis (MIPO).

STUDY DESIGN

Prospective clinical trial.

SAMPLE POPULATION

Fifteen client owned dogs.

METHODS

Virtual 3D models of both pelvic limbs were created. Pin guides were designed to conform to the proximal and distal tibia. A reduction bridge was designed to align the pin guides based on the guides' spatial location. Guides were 3D printed, sterilized, and applied, in conjunction with transient application of a circular fixator, to facilitate indirect fracture realignment before plate application. Alignment of the stabilized tibiae was assessed using postoperative computed tomography scans.

RESULTS

Mean duration required for virtual planning was 2.5 h and a mean of 50.7 h elapsed between presentation and surgery. Guide placement was accurate with minor median discrepancies in translation and frontal, sagittal, and axial plane positioning of 2.9 mm, 3.6°, 2.7°, and 6.8°, respectively. Application of the reduction system restored mean tibial length and frontal, sagittal, and axial alignment within 1.7 mm, 1.9°, 1.7°, and 4.5°, respectively, of the contralateral tibia.

CONCLUSION

Design and fabrication of a 3D-printed, patient-specific fracture reduction system is feasible in a relevant clinical timeline. Intraoperative pin-guide placement was reasonably accurate with minor discrepancies compared to the virtual plan. Custom 3D-printed reduction system application facilitated near-anatomic or acceptable fracture reduction in all dogs.

CLINICAL SIGNIFICANCE

Virtual planning and fabrication of a 3D-printing patient-specific fracture reduction system is practical and facilitated acceptable, if not near-anatomic, fracture alignment during MIPO.

Quality assurance of 3D-printed patient specific anatomical models: a systematic review

BACKGROUND

The responsible use of 3D-printing in medicine includes a context-based quality assurance. Considerable literature has been published in this field, yet the quality of assessment varies widely. The limited discriminatory power of some assessment methods challenges the comparison of results. The total error for patient specific anatomical models comprises relevant partial errors of the production process: segmentation error (SegE), digital editing error (DEE), printing error (PrE). The present review provides an overview to improve the general understanding of the process specific errors, quantitative analysis, and standardized terminology.

METHODS

This review focuses on literature on quality assurance of patient-specific anatomical models in terms of geometric accuracy published before December 4th, 2022 (n = 139). In an attempt to organize the literature, the publications are assigned to comparable categories and the absolute values of the maximum mean deviation (AMMD) per publication are determined therein.

RESULTS

The three major examined types of original structures are teeth or jaw (n = 52), skull bones without jaw (n = 17) and heart with coronary arteries (n = 16). VPP (vat photopolymerization) is the most frequently employed basic 3D-printing technology (n = 112 experiments). The median values of AMMD (AMMD: The metric AMMD is defined as the largest linear deviation, based on an average value from at least two individual measurements.) are 0.8 mm for the SegE, 0.26 mm for the PrE and 0.825 mm for the total error. No average values are found for the DEE.

CONCLUSION

The total error is not significantly higher than the partial errors which may compensate each other. Consequently SegE, DEE and PrE should be analyzed individually to describe the result quality as their sum according to rules of error propagation. Current methods for quality assurance of the segmentation are often either realistic and accurate or resource efficient. Future research should focus on implementing models for cost effective evaluations with high accuracy and realism. Our system of categorization may be enhancing the understanding of the overall process and a valuable contribution to the structural design and reporting of future experiments. It can be used to educate specialists for risk assessment and process validation within the additive manufacturing industry.

Comparison of three-dimensional printed patient-specific guides versus freehand approach for radial osteotomies in normal dogs: Ex vivo model

OBJECTIVE

To compare the accuracy of three-dimensional (3D) printed patient-specific guide (PSG) with a freehand (FH) approach for radial osteotomies in ex vivo normal dogs.

STUDY DESIGN

Experimental study.

ANIMALS

Twenty four ex vivo thoracic limb pairs from normal beagle dogs.

METHODS

Computed tomography (CT) images were collected preoperatively and postoperatively. Three osteotomies tested (n = 8/group) were: (1) uniplanar 30° frontal plane wedge ostectomy, (2) oblique plane (30° frontal, 15° sagittal) wedge ostectomy, and (3) single oblique plane osteotomy (SOO, 30° frontal, 15° sagittal, and 30° external). Limb pairs were randomized to a 3D PSG or FH approach. The resultant osteotomies were compared with virtual target osteotomies by surface shape-matching postoperative to the preoperative radii.

RESULTS

The mean ± standard deviation osteotomy angle deviation for all 3D PSG osteotomies (2.8 ± 2.8°, range 0.11-14.1°) was less than for the FH osteotomies (6.4 ± 6.0°, range 0.03-29.7°). No differences were found for osteotomy location in any group. In total, 84% of 3D PSG osteotomies were within 5° deviance from the target compared to 50% of freehand osteotomies.

CONCLUSION

Three-dimensional PSG improved FH accuracy of osteotomy angle in select planes and the most complex osteotomy orientation in a normal ex vivo radial model.

CLINICAL SIGNIFICANCE

Three-dimensional PSGs provided more consistent accuracy, which was most notable in complex radial osteotomies. Future work is needed to investigate guided osteotomies in dogs with antebrachial bone deformities.

Biomechanical comparison of titanium alloy additively manufactured and conventionally manufactured plate-screw constructs

AIM

To biomechanically compare the bending stiffness, strength, and cyclic fatigue of titanium additively manufactured (AM) and conventionally manufactured (CM) limited contact plates (LCP) of equivalent dimensions using plate-screw constructs.

METHODS

Twenty-four 1.5/2.0-mm plate constructs (CM: n = 12; AM: n = 12) were placed under 4-point bending conditions. Data were collected during quasi-static single cycle to failure and cyclic fatigue testing until implants plastically deformed or failed. Bending stiffness, bending structural stiffness, and bending strength were determined from load-displacement curves. Fatigue life was determined as number of cycles to failure. Median test variables for each method were compared using the Wilcoxon rank sum test within each group. Fatigue data was also analysed by the Kaplan-Meier estimator of survival function.

RESULTS

There was no evidence for a difference in bending stiffness and bending structural stiffness between AM and CM constructs. However, AM constructs exhibited greater bending strength (median 3.07 (min 3.0, max 3.4) Nm) under quasi-static 4-point bending than the CM constructs (median 2.57 (min 2.5, max 2.6) Nm, p = 0.006). Number of cycles to failure under dynamic 4-point bending was higher for the CM constructs (median 164,272 (min 73,557, max 250,000) cycles) than the AM constructs (median 18,704 (min 14,427, max 33,228) cycles; p = 0.02). Survival analysis showed that 50% of AM plates failed by 18,842 cycles, while 50% CM plates failed by 78,543 cycles.

CONCLUSION AND CLINICAL RELEVANCE

Additively manufactured titanium implants, printed to replicate a conventional titanium orthopaedic plate, were more prone to failure in a shorter fatigue period despite being stronger in single cycle to failure. Patient-specific implants made using this process may be brittle and therefore not comparable to CM orthopaedic implants. Careful selection of their use on a case/patient-specific basis is recommended.

Use of Preoperative 3D Virtual Planning and 3D-Printed Patient-Specific Guides to Facilitate a Single-Stage Cranial Closing Wedge Ostectomy and Tibial Plateau Leveling Osteotomy Procedure to Address Proximal Tibial Deformity, an Excessive Tibial Plateau Angle, and Cranial Cruciate Ligament Insufficiency in a Dog

A 9-month-old mixed-breed dog was presented for bilateral proximal tibial deformity resulting in an excessive tibial plateau angle and cranial cruciate ligament insufficiency. Initial surgical management of the right pelvic limb was done by performing a cranial closing wedge ostectomy. Inadequate leveling of the plateau resulted in a postliminal meniscal tear which was addressed during a revision tibial plateau leveling osteotomy. The left pelvic limb was managed in a single-session surgery using three-dimensional (3D) virtual surgical planning and custom 3D-printed surgical guides to perform a combined cranial closing wedge ostectomy and tibial plateau leveling osteotomy. Postoperative 3D analysis of the left tibia revealed the accuracy of the surgical result within 2° of the virtual surgical plan. The dog developed a transient grade II/IV left medial patellar luxation following surgery but ultimately attained a full functional recovery and was actively engaged in competitive agility work 46 months following surgery on the left pelvic limb.