Abstract
Objectives: Tibial shaft fractures are common yet challenging to manage, with external fixation being a standard approach. This study aimed to compare functional recovery between two reduction and fixation techniques: traditional fluoroscopy-assisted external fixators and novel 3D-printed automatic reset splints. Methods: A retrospective analysis included 193 patients with open tibial shaft fractures treated between January 2021 and December 2024. Participants were divided into a traditional fluoroscopy-assisted (TF-A) group (n=104) and a 3D-printed automatic reset splint (3D-P) group (n=89). Reduction effectiveness was assessed using radiographic measurements (X, α, Y, Z, β) preoperatively and at 1 week, 1 month, 3months, and 6 months postoperatively. Healing status (callus formation and healing time), treatment efficacy, complication rates, knee function (HSS score), and pain intensity (VAS score) were evaluated during a 6-month follow-up. Results: The 3D-P group demonstrated significantly better reduction across most deformity parameters (e.g., 1-week Y: 2.43±0.78 mm vs. 2.76±0.86 mm, P=0.006), shorter callus formation time (16.84±3.12 vs. 18.49±4.28 days, P=0.002), and faster fracture healing (72.97±10.93 vs. 78.26±15.33 days, P=0.006). Excellent efficacy rates were higher (69.66% vs. 51.92%, P=0.012), and total complications lower (20.22% vs. 33.65%, P=0.037). The 3D-P group also had superior knee function (HSS: 86.62±6.44 vs. 84.33±5.39, P=0.008) and lower pain VAS scores at all postoperative timepoints (e.g., 1 week: 4.93±0.86 vs. 5.37±1.02, P=0.002). Conclusions: Three-dimensional printed automatic reset splints offer significant advantages over traditional fluoroscopy-assisted fixation in improving reduction accuracy, accelerating healing, reducing complications, and enhancing functional recovery in tibial shaft fractures.
Keywords: 3D printing, external fixators, tibial fractures, fracture fixation, rehabilitation
Introduction
Tibial shaft fractures represent a significant clinical challenge in orthopedic trauma, constituting approximately 2% of all fractures and often resulting from high-energy mechanisms such as traffic accidents or falls from height [1,2]. The management of these injuries, particularly open fractures, is complex due to the precarious soft tissue envelope, limited vascular supply, and high mechanical demands placed on the tibia. The primary treatment objectives are to achieve anatomical reduction, provide stable fixation, preserve biological viability, and facilitate early functional rehabilitation-all of which are critical for restoring limb function and preventing long-term disability [3,4].
External fixation has long been a cornerstone in the initial and in some cases, definitive management of open tibial shaft fractures, especially in situations with substantial soft tissue compromise [5,6]. Traditional fluoroscopy-assisted (TF-A) reduction and external fixation offers the advantages of being minimally invasive and providing adjustable stability. However, this technique relies heavily on intraoperative two-dimensional imaging, which can lead to suboptimal reduction accuracy, increased radiation exposure, and prolonged operative time. Imperfect reduction may contribute to malunion, delayed healing, and altered biomechanics, ultimately compromising functional outcomes [7,8].
The inherent limitations of conventional methods have spurred the exploration of advanced technologies for improved fracture care. The integration of three-dimensional (3D) printing technology represents a paradigm shift toward personalized and precision medicine in orthopedics [9,10]. This approach involves acquiring preoperative computed tomography (CT) data of the affected limb, performing a virtual reduction in a digital environment, and then using computer-aided design (CAD) to create a patient-specific external fixation splint that mirrors the individual’s anatomy and the reduced fracture position [11,12]. This customized splint is then manufactured using 3D printing.
This innovative workflow potentially addresses several key limitations of traditional methods. First, regarding precision and stability, by translating a precise preoperative virtual plan into physical reality, 3D-printed splints may achieve superior fracture reduction accuracy and maintain it more consistently, thereby minimizing intraoperative guesswork [13]. Second, concerning biological benefits, the personalized design that accounts for soft tissue contours may minimize iatrogenic soft tissue damage and better preserve the vascular supply, creating a more favorable biological environment for bone healing [13,14]. Third, in terms of clinical outcomes, the improved stability and biological respect could translate into faster healing rates, reduced risks of complications such as infection and malunion, and enhanced functional recovery [10,13]. It is within this context of addressing persistent challenges in tibial fracture management that this study was conceived, aiming to evaluate whether this novel 3D-printed automatic reset splint translates into superior functional recovery compared to traditional fluoroscopy-assisted external fixation.
Materials and methods
Selection criteria
A retrospective analysis was conducted on 193 patients with tibial shaft fractures admitted to Shenzhen Pingle Orthopaedic Hospital Affiliated to Guangzhou University of Traditional Chinese Medicine from January 2021 to December 2024. Inclusion criteria: ① Age between 18 and 70 years; ② Clinically diagnosed with unilateral tibial shaft open fracture [15]; ③ Gustilo classification [16] of type II or IIIA; ④ AO Foundation [17] classification of type A or B; ⑤ Time from injury to treatment <10 days; ⑥ Complete medical records without any missing data. Exclusion criteria: ① Old fractures, pathological fractures, severely comminuted fractures, or fractures that are difficult to accurately reduce; ② Concomitant fractures or joint dislocations in other parts of the same lower limb; ③ Previous history of lower limb fractures, deformities, fracture surgeries, or orthopedic surgeries on either side; ④ Systemic diseases affecting fracture healing; ⑤ Nerve injuries or vascular injuries; ⑥ Follow-up period <6 months.
This retrospective study was conducted in accordance with the ethical principles of the Declaration of Helsinki and was approved by the ethics committee of Shenzhen Pingle Orthopaedic Hospital Affiliated to Guangzhou University of Traditional Chinese Medicine. The need for informed consent was waived by the ethics committee due to the retrospective nature of the study.
Grouping criteria
Based on different external fixation treatment methods, 193 eligible patients with open tibial shaft fractures were divided into two groups: the traditional fluoroscopy-assisted (TF-A) group (n=104) and the 3D-printed (3D-P) group (n=89). Patients in the TF-A group received reduction and fixation treatment using a traditional external fixator assisted by C-arm X-ray fluoroscopy, while patients in the 3D-P group received treatment with a 3D-printed automatic reset external fixation splint based on preoperative CT three-dimensional reconstruction. All surgeries were performed by the same physician with over five years of experience in external fixation treatment for tibial shaft fractures.
Treatment process
Traditional fluoroscopy-assisted reduction external fixators
For patients in the TF-A group, they were placed in a supine position, and the operating table was adjusted to ensure patient comfort and easy exposure of the surgical site. An inflatable tourniquet was applied to the root of the affected thigh. After successful general anesthesia, open wounds were thoroughly disinfected and debrided, and suturable wounds were closed. Non-suturable wounds were covered with negative pressure wound therapy. Anteromedial or anterolateral incisions were made, with 5 cm incisions above and below the fracture site to expose the fracture ends by cutting through the skin and subcutaneous tissue. Reduction was assisted using reduction clamps and bone levers under fluoroscopic guidance provided by a C-arm X-ray machine (Cstar, Hangzhou MeNowa Medical Technology Co., Ltd., China), aiming to restore the original axis and length of the tibia as much as possible. After reduction, an external fixator was applied.
A 4 mm diameter K-wire was drilled into the cortical bone segment. Initially, the bilateral external fixation rods were fixed, then two distant K-wires at the proximal and distal ends were connected for fracture reduction. Additional K-wires were inserted 3-4 cm from the fracture ends at both the proximal and distal sites. The position of the fixator was adjusted to ensure proper alignment of the fracture ends, and screws were used to secure the proximal and distal segments. Upon completion of the surgery, the wound was thoroughly examined to ensure there was no active bleeding or other abnormalities, cleaned, and closed using absorbable sutures for continuous suturing of the subcutaneous tissue and skin.
3D-printed automatic reset splints
(1) Patient’s CT 3D reconstruction: Preoperative scans of the affected limb and the contralateral healthy limb were performed using a CT scanner (SOMATOM Definition Flash, Siemens, Germany). The scanning parameters were set as follows: slice thickness (0.625 mm); voltage (120 kV); current (300 mA). The acquired Digital Imaging and Communications in Medicine (DICOM) files were imported into Mimics software v19.0 (Materialise, Leuven, Belgium). Using functions such as “threshold segmentation” and “layer editing”, images of external fixation pins, bones, and skin contours were segmented (thresholds set at >2500 HU, 500-2000 HU, and <300 HU, respectively), and then 3D reconstructions were sequentially performed using the software’s “3D reconstruction” feature.
(2) Virtual reduction: Under the guidance of an orthopedic surgeon, the “translation” and “rotation” functions of Mimics v19.0 were used to move the distal bone segment (along with its external fixation pins) so that the fracture surfaces aligned with those of the proximal segment, completing the virtual reduction. When the fracture site had multiple fragments or bone defects, making it difficult to align based on surface details, the healthy-side bone was mirrored and used as a template for fracture reduction.
(3) Design and manufacturing of 3D printed automatic reduction external fixation splints: The 3D images of skin contours, reduced bones, and external fixation pins were exported from Mimics 19.0 software as STL files and then imported into SolidWorks 2014 software for assembly. Soft tissue injury sites were marked on the skin contour. Based on the anticipated postoperative swelling, the skin contour was expanded by an appropriate distance (typically 3 mm) and thickened by 5 mm to form the prototype of the 3D printed automatic reduction external fixation splint. Corresponding fixation holes and pressure pads were designed according to the positions of the external fixation pins. The scaffold was divided into four parts based on the positions of the fixation holes, followed by optimization designs such as hollowing, cutting, reinforcing, and drilling. Finally, the exposed heights of the external fixation pins on the scaffold were recorded, or corresponding height detection rulers were designed. The designed scaffold in SolidWorks 2014 was exported as an STL file, then imported into 3D printing software (Cura software v15.02) for pose adjustment, automatic layering, and support structure generation. The generated data were then transmitted to a 3D printer (3D ORTHO Waston Med Co., Ltd., Changzhou, Jiangsu, China). After printing, the support structures were removed, and post-processing such as polishing and cleaning was performed.
(4) Surgical execution based on virtual reduction plan: After removing the temporary external fixator, the affected limb was placed into a sterilized 3D-printed automated reduction external fixator. First, the proximal external fixation pins were inserted into the corresponding fixing holes at the proximal end of the fixator and preliminarily tightened after adjusting their exposed height to a predetermined value using a pre-designed height detection ruler. At this stage, the fixator ensured the accuracy of the proximal screw positions. Subsequently, traction was applied along the axial direction of the limb. During traction, changes in the soft tissue tension of the affected limb guided the distal bone segment’s movement according to the inner surface morphology of the fixator. The personalized three-dimensional structure of the fixator played an “automatic reduction” role at this moment, passively guiding the distal bone fragment to the anatomical position predetermined by the virtual plan. Next, the distal external fixation pins were slid into the corresponding fixing holes at the distal end of the fixator. After ensuring the accurate positioning and height adjustment of both proximal and distal pins, connecting rods and clamps were used to securely connect all external fixation pins into a complete rigid frame. Finally, fluoroscopy was performed using a C-arm X-ray machine (Cstar, Hangzhou MeNowa Medical Technology Co., Ltd., China) to confirm the consistency between the fracture reduction effect and the virtual plan.
Postoperative care
All patients received the following routine external fixation care postoperatively: (1) The needle insertion sites were disinfected 2 to 3 times a day using medical alcohol; (2) Dressings were changed regularly based on soft tissue healing status (if there was no significant exudate, dressing changes were not necessary); (3) The fixation screws of the external fixator were checked regularly to prevent loosening; (4) Patients with satisfactory reduction and stable fixation were allowed to perform non-weight-bearing joint functional exercises postoperatively; (5) Partial weight-bearing was permitted 1 week postoperatively.
Function recovery indicators
The primary outcome measures of this study were reduction effectiveness, postoperative healing status, efficacy evaluation, and incidence of complications. The secondary outcome measures were knee function scores and pain intensity scores. All patients completed a 6-month follow-up period.
(1) Reset effect: Preoperative and at 1 week, 1 month, 3 months, and 6 months postoperative, anteroposterior and lateral radiographs of the tibial fracture specimens were taken to measure the following deformity parameters: mediolateral displacement (X), mediolateral angulation (α), axial displacement (Y), anteroposterior displacement (Z), and anteroposterior angulation (β). X was the maximum perpendicular distance between the fractured fragments in the coronal plane. α was the angle of deformity in the coronal plane, measured as the angle between the longitudinal axes of the proximal and distal main fragments. Y was the maximum shortening or overriding of the fracture fragments along the long axis of the tibia. Z was the maximum perpendicular distance between the fractured fragments in the sagittal plane. β was the angle of deformity in the sagittal plane, measured as the angle between the longitudinal axes of the proximal and distal main fragments (Figures 1 and 2).
Figure 1.
Lateral X-ray of a typical case in TF-A group. A. Pre-operative lateral X-ray showed fracture lines; B. Lateral X-ray at 1 day after external fixator fixation showed the external fixator needle was correctly placed, fracture end was stable and fixed, and fracture end was well aligned. TF-A, Traditional Fluoroscopy-Assisted.
Figure 2.
Lateral X-ray of a typical case in 3D-P group. A. Pre-operative lateral X-ray showed the fracture line and fracture fragment was misaligned; B. Lateral X-ray at 1 day after external fixation surgery showed that the external fixator pins were correctly positioned, providing stable fixation of the fracture ends with good alignment. 3D-P, 3D-Printed.
(2) Postoperative Healing Status: Bone callus formation and fracture healing time were assessed according to the criteria outlined in the “Chinese Guidelines for Diagnosis and Treatment of Open Fractures (2019 Edition)” [15]. Bone callus formation was determined by the following signs: blurred fracture lines, reduced soft tissue swelling, and the appearance of sclerotic borders around the fracture site on X-ray. The criteria for fracture healing included: absence of longitudinal percussion pain, tenderness, or abnormal movement at the fracture site; blurred fracture lines with continuous bone callus observed on X-rays; ability to lift a 1 kg weight forward for 1 minute with the upper limb after removal of external fixation, or continuous walking for 3 minutes and ≥30 steps on flat ground with the lower limb; and no change in fracture stability over a continuous observation period of 2 weeks.
(3) Efficacy evaluation: The study adopted the commonly used domestic criteria for evaluating the efficacy of long bone fracture treatment (see Table 1).
Table 1.
Criteria for evaluating the efficacy of long bone fracture treatment in China
| Joint Activity | Pain | Angular Deformity | Shortening Deformity | |
|---|---|---|---|---|
| Excellent | Normal range of motion restored | None | None | <1 cm |
| Good | Motion restricted by <50% | Occasional | None | <2 cm |
| General | Motion restricted by >50% | Frequent | <10° | <3 cm |
(4) Incidence of complications: The occurrence of complications, including superficial infection, deep infection, pin tract infection, malunion, and nonunion, were observed and compared during the follow-up period. Infection-related conditions were a key focus of this study. Superficial infections were defined as infections involving the skin and subcutaneous tissues around the needle tract or surgical incision, characterized by local redness, swelling, heat, pain, and purulent discharge. Deep infections were defined as infections that involve the deep fascia, muscles, or bone tissue, potentially accompanied by systemic infection symptoms (such as fever), and confirmed through imaging studies (e.g., X-rays showing bone destruction) or pathogen culture. Pin tract infections were defined as bacterial infections occurring at the interface between the needle and the skin, forming a channel (i.e., “needle tract”). The diagnosis of all infection events was based on a combination of clinical signs, laboratory tests, and imaging assessments.
(5) Knee function scores: The Hospital for Special Surgery (HSS) scoring system was used to compare knee function scores between the two groups at preoperative and 6 months postoperative. The HSS score evaluates pain, function, range of motion, muscle strength, and other aspects, with a total score of 100 points; higher scores indicate better knee function in patients. The Cronbach’s alpha for this scale is 0.87 [18].
(6) Pain intensity scores: The Visual Analog Scale (VAS) was utilized to assess the pain intensity of patients in both groups at preoperative, 1 week, 1 month, 3 months, and 6 months postoperative. The VAS score ranges from 0 to 10, with higher scores indicating more severe pain. The intraclass correlation coefficient for test-retest reliability of this scale ranges from 0.97 to 0.99 [19].
Statistics
In this study, statistical analyses were performed using SPSS software (Version 29.0; developed by SPSS Inc., Chicago, IL, USA). Continuous variables were assessed for normality using the Shapiro-Wilk test and were reported as means ± standard deviations (means ± SD) since they met the criteria for normal distribution. For comparisons between groups, independent samples t-tests were employed. Categorical variables were presented as frequencies and percentages [n (%)] and were compared between groups using the chi-square test. The significance level was set at α=0.05.
Results
Basic data
In comparing the demographic characteristics between the TF-A group (n=104) and the 3D-P group (n=89), our results indicated no significant differences in age, gender distribution, BMI, insurance type, educational background, occupational type, marital status, smoking history, drinking history, hypertension, and diabetes between the two groups (all P>0.05). These findings suggest that the baseline demographic characteristics were well balanced across the treatment groups, ensuring comparability for further analysis on functional recovery outcomes (Table 2).
Table 2.
Comparison of demographic characteristics between two groups
| Parameter | TF-A group (n=104) | 3D-P group (n=89) | t/χ2 | P |
|---|---|---|---|---|
| Age (years) | 41.75±8.36 | 40.92±8.51 | 0.683 | 0.495 |
| Gender [n (%)] | 0.638 | 0.424 | ||
| Male | 70 (67.31%) | 55 (61.80%) | ||
| Female | 34 (32.69%) | 34 (38.20%) | ||
| BMI (kg/m2) | 23.22±2.15 | 23.27±2.19 | 0.150 | 0.881 |
| Insurance type [n (%)] | 0.729 | 0.694 | ||
| Urban insurance | 62 (59.62%) | 48 (53.93%) | ||
| Rural medical insurance | 30 (28.85%) | 28 (31.46%) | ||
| Self-payment | 12 (11.54%) | 13 (14.61%) | ||
| Educational background [n (%)] | 1.019 | 0.601 | ||
| Junior high or below | 38 (36.54%) | 27 (30.34%) | ||
| High school | 45 (43.27%) | 40 (44.94%) | ||
| Tertiary and above | 21 (20.19%) | 22 (24.72%) | ||
| Occupational type [n (%)] | 0.796 | 0.372 | ||
| Manual labor | 65 (62.50%) | 50 (56.18%) | ||
| Mental labor | 39 (37.50%) | 39 (43.82%) | ||
| Marital status [n (%)] | 0.679 | 0.712 | ||
| Married | 72 (69.23%) | 57 (64.04%) | ||
| Single | 25 (24.04%) | 26 (29.21%) | ||
| Divorced/Widowed | 7 (6.73%) | 6 (6.74%) | ||
| Smoking history [n (%)] | 0.232 | 0.630 | ||
| Yes | 48 (46.15%) | 38 (42.70%) | ||
| No | 56 (53.85%) | 51 (57.30%) | ||
| Drinking history [n (%)] | 0.039 | 0.843 | ||
| Yes | 40 (38.46%) | 33 (37.08%) | ||
| No | 64 (61.54%) | 56 (62.92%) | ||
| Hypertension [n(%)] | 0.001 | 0.974 | ||
| Yes | 22 (21.15%) | 19 (21.35%) | ||
| No | 82 (78.85%) | 70 (78.65%) | ||
| Diabetes [n (%)] | 0.175 | 0.676 | ||
| Yes | 15 (14.42%) | 11 (12.36%) | ||
| No | 89 (85.58%) | 78 (87.64%) |
Notes: TF-A, Traditional Fluoroscopy-Assisted; 3D-P, 3D-Printed; BMI, Body Mass Index.
In the comparison of fracture features between the TF-A group and the 3D-P group, no significant differences were observed across various parameters. There were no significant differences in the cause of fracture, site of fracture, side of fracture, type of fracture, AO classification, Gustilo classification, soft tissue defect size, and time from injury to operation between the two groups (all P>0.05). These results indicate that the baseline fracture characteristics were similar between the two treatment groups, supporting comparability for further analysis on the effectiveness of the treatments (Table 3).
Table 3.
Comparison of fracture features between two groups
| Parameter | TF-A group (n=104) | 3D-P group (n=89) | t/χ2 | P |
|---|---|---|---|---|
| Cause of fracture [n (%)] | 1.687 | 0.640 | ||
| Traffic accident injuries | 58 (55.77%) | 46 (51.69%) | ||
| Fall from height injuries | 30 (28.85%) | 23 (25.84%) | ||
| Mechanical injuries | 13 (12.50%) | 17 (19.10%) | ||
| Other causes | 3 (2.88%) | 3 (3.37%) | ||
| Site of fracture [n (%)] | 0.357 | 0.836 | ||
| Upper | 25 (24.04%) | 20 (22.47%) | ||
| Middle | 40 (38.46%) | 38 (42.70%) | ||
| Lower | 39 (37.50%) | 31 (34.83%) | ||
| Side of fracture [n (%)] | 0.635 | 0.426 | ||
| Left | 48 (46.15%) | 36 (40.45%) | ||
| Right | 56 (53.85%) | 53 (59.55%) | ||
| Type of fracture [n (%)] | 0.220 | 0.896 | ||
| Transverse | 45 (43.27%) | 36 (40.45%) | ||
| Oblique | 32 (30.77%) | 30 (33.71%) | ||
| Spiral | 27 (25.96%) | 23 (25.84%) | ||
| AO classification [n (%)] | 0.015 | 0.903 | ||
| A | 57 (54.81%) | 48 (53.93%) | ||
| B | 47 (45.19%) | 41 (46.07%) | ||
| Gustilo classification [n (%)] | 0.092 | 0.762 | ||
| II | 63 (60.58%) | 52 (58.43%) | ||
| III A | 41 (39.42%) | 37 (41.57%) | ||
| Soft tissue defect (cm2) | 5.32±1.25 | 5.28±1.31 | 0.207 | 0.837 |
| Time from injury to operation (days) | 4.28±0.76 | 4.35±0.88 | 0.591 | 0.555 |
Notes: TF-A, Traditional Fluoroscopy-Assisted; 3D-P, 3D-Printed; AO, AO Foundation.
Reset effect
When evaluating the reset effect between the TF-A group and the 3D-P group, several parameters showed significant differences postoperatively. Preoperative measurements for all parameters (X, α, Y, Z, β) did not show any significant differences between the two groups (all P>0.05). For X (Medial-Lateral Displacement), there were significant differences at 1 week (P=0.003), 1 month (P=0.015), 3 months (P=0.018), but not at 6 months (P>0.05). For α (Medial-Lateral Angulation), significant differences were noted at 1 week (P=0.021), 1 month (P=0.023), 3 months (P=0.021), and 6 months (P=0.021). Y (Axial Displacement) showed significant differences at 1 week (P=0.006), 1 month (P=0.011), 3 months (P=0.040), and 6 months (P=0.047). Z (Anterior-Posterior Displacement) demonstrated significant differences at 1 week (P=0.013), 1 month (P=0.016), 3 months (P=0.019), but not at 6 months (P>0.05). For β (Anterior-Posterior Angulation), significant differences were observed at 1 week (P=0.008), 1 month (P=0.018), 3 months (P=0.045), and 6 months (P=0.039). These results indicate that the 3D-printed automatic resetting splints provided a significantly better reset effect compared to traditional fluoroscopy-assisted external fixation during the early stages of recovery, with sustained improvements over time (Table 4).
Table 4.
Comparison of reset effect between two groups
| Parameter | TF-A group (n=104) | 3D-P group (n=89) | t | P |
|---|---|---|---|---|
| X (mm) | ||||
| Preoperatively | 8.52±2.31 | 8.47±2.28 | 0.151 | 0.880 |
| 1 week postoperatively | 3.35±0.98 | 2.95±0.86 | 3.002 | 0.003 |
| 1 month postoperatively | 3.13±0.95 | 2.82±0.83 | 2.442 | 0.015 |
| 3 months postoperatively | 3.05±0.92 | 2.77±0.71 | 2.377 | 0.018 |
| 6 months postoperatively | 2.92±0.73 | 2.75±0.66 | 1.593 | 0.113 |
| α (°) | ||||
| Preoperatively | 12.35±3.42 | 12.28±3.38 | 0.138 | 0.891 |
| 1 week postoperatively | 5.43±1.75 | 4.87±1.56 | 2.335 | 0.021 |
| 1 month postoperatively | 5.27±1.62 | 4.76±1.44 | 2.299 | 0.023 |
| 3 months postoperatively | 5.19±1.48 | 4.72±1.31 | 2.325 | 0.021 |
| 6 months postoperatively | 5.07±1.33 | 4.65±1.19 | 2.326 | 0.021 |
| Y (mm) | ||||
| Preoperatively | 7.25±2.12 | 7.18±2.09 | 0.234 | 0.815 |
| 1 week postoperatively | 2.76±0.86 | 2.43±0.78 | 2.798 | 0.006 |
| 1 month postoperatively | 2.62±0.84 | 2.32±0.76 | 2.563 | 0.011 |
| 3 months postoperatively | 2.48±0.75 | 2.26±0.71 | 2.07 | 0.040 |
| 6 months postoperatively | 2.45±0.74 | 2.25±0.66 | 2.002 | 0.047 |
| Z (mm) | ||||
| Preoperatively | 7.92±2.28 | 7.87±2.25 | 0.150 | 0.881 |
| 1 week postoperatively | 3.09±0.92 | 2.76±0.88 | 2.507 | 0.013 |
| 1 month postoperatively | 2.92±0.88 | 2.62±0.84 | 2.436 | 0.016 |
| 3 months postoperatively | 2.87±0.85 | 2.58±0.82 | 2.368 | 0.019 |
| 6 months postoperatively | 2.74±0.82 | 2.54±0.79 | 1.774 | 0.078 |
| β (°) | ||||
| Preoperatively | 11.25±3.17 | 11.18±3.15 | 0.145 | 0.885 |
| 1 week postoperatively | 4.47±1.43 | 3.95±1.26 | 2.665 | 0.008 |
| 1 month postoperatively | 4.34±1.41 | 3.88±1.24 | 2.386 | 0.018 |
| 3 months postoperatively | 4.31±1.32 | 3.94±1.22 | 2.017 | 0.045 |
| 6 months postoperatively | 4.16±1.27 | 3.79±1.15 | 2.077 | 0.039 |
Notes: TF-A, Traditional Fluoroscopy-Assisted; 3D-P, 3D-Printed; X, Medial-Lateral Displacement; α, Medial-Lateral Angulation; Y, Axial Displacement; Z, Anterior-Posterior Displacement; β, Anterior-Posterior Angulation.
Postoperative healing status
In evaluating the postoperative healing status between the TF-A group and the 3D-P group, significant differences were observed in both the time to callus formation and fracture healing time. The time to callus formation was significantly shorter in the 3D-P group compared to the TF-A group (P=0.002). Similarly, the fracture healing time was also significantly reduced in the 3D-P group (P=0.006). These results suggest that the use of 3D-printed automatic resetting splints is associated with a faster healing process, including quicker callus formation and overall fracture healing, compared to traditional fluoroscopy-assisted external fixation (Figure 3).
Figure 3.
Comparison of postoperative healing status between two groups (days). Notes: TF-A, Traditional Fluoroscopy-Assisted; 3D-P, 3D-Printed; **: P<0.01.
Efficacy evaluation
In the comparison of efficacy evaluation between the TF-A group and the 3D-P group, significant differences were observed in the distribution of outcomes. The 3D-P group had a significantly higher proportion of patients achieving an “excellent” outcome compared to the TF-A group (P=0.012). There was no significant difference in the proportion of patients achieving a “good” outcome or a “general” outcome (all P>0.05) between the two groups. These findings indicate that the use of 3D-printed automatic resetting splints is associated with a higher rate of excellent treatment outcomes compared to traditional fluoroscopy-assisted external fixation, suggesting potential advantages of this advanced technology in improving overall treatment efficacy (Table 5).
Table 5.
Comparison of efficacy evaluation between two groups [n (%)]
| Parameter | TF-A group (n=104) | 3D-P group (n=89) | χ2 | P |
|---|---|---|---|---|
| Excellent | 54 (51.92%) | 62 (69.66%) | 6.294 | 0.012 |
| Good | 38 (36.54%) | 22 (24.72%) | 3.127 | 0.077 |
| General | 12 (11.54%) | 5 (5.62%) | 2.093 | 0.148 |
Notes: TF-A, Traditional Fluoroscopy-Assisted; 3D-P, 3D-Printed.
Incidence of complications
In the comparison of complications incidence rates between the TF-A group and the 3D-P group, the total complication rate was significantly lower in the 3D-P group compared to the TF-A group (20.22% vs 33.65%, χ2=4.342, P=0.037). Specifically, there were fewer cases of superficial infection (6.74% vs 14.42%), deep infection (1.12% vs 4.81%), pin tract infection (10.11% vs 19.23%), malunion (4.49% vs 12.50%), and nonunion (2.25% vs 6.73%) in the 3D-P group, although individual complication rates did not reach statistical significance on their own. These results suggest that the use of 3D-printed automatic resetting splints is associated with a reduced overall incidence of postoperative complications compared to traditional fluoroscopy-assisted external fixation. This indicates that using advanced 3D printing technology has the potential to reduce the risk of various complications, including infection, after the treatment of tibial shaft fractures (Table 6).
Table 6.
Comparison of complications incidence rates between two groups [n (%)]
| Parameter | TF-A group (n=104) | 3D-P group (n=89) | χ2 | P |
|---|---|---|---|---|
| Total complication rate | 35 (33.65%) | 18 (20.22%) | 4.342 | 0.037 |
| Superficial infection | 15 (14.42%) | 6 (6.74%) | ||
| Deep infection | 5 (4.81%) | 1 (1.12%) | ||
| Pin tract infection | 20 (19.23%) | 9 (10.11%) | ||
| Malunion | 13 (12.50%) | 4 (4.49%) | ||
| Nonunion | 7 (6.73%) | 2 (2.25%) |
Notes: TF-A, Traditional Fluoroscopy-Assisted; 3D-P, 3D-Printed.
Knee joint function score
In the comparison of knee joint function scores between the TF-A group and the 3D-P group, significant differences were observed in several parameters at the 6-month postoperative evaluation. Preoperative scores for pain, function, range of motion, muscle strength, and total score did not show any significant differences between the two groups (all P>0.05). For pain, there was a significant difference favoring the 3D-P group (P=0.006). Function scores also showed a significant improvement in the 3D-P group compared to the TF-A group (P=0.001). The range of motion demonstrated a significant difference at 6 months postoperatively (P=0.018). Muscle strength scores were significantly higher in the 3D-P group at 6 months postoperatively (P=0.016). Finally, the total knee joint function score was significantly better in the 3D-P group compared to the TF-A group at 6 months postoperatively (P=0.008). These results indicate that the use of 3D-printed automatic resetting splints is associated with better knee joint functional recovery at 6 months postoperatively compared to traditional fluoroscopy-assisted external fixation (Table 7).
Table 7.
Comparison of knee joint function score between two groups (points)
| Parameter | TF-A group (n=104) | 3D-P group (n=89) | t | P |
|---|---|---|---|---|
| Pain | ||||
| Preoperatively | 17.56±4.83 | 18.85±4.67 | 1.864 | 0.064 |
| 6 months postoperatively | 23.03±4.48 | 24.92±4.84 | 2.807 | 0.006 |
| Function | ||||
| Preoperatively | 12.06±2.35 | 11.45±2.37 | 1.784 | 0.076 |
| 6 months postoperatively | 18.13±2.96 | 19.71±3.65 | 3.276 | 0.001 |
| Range of motion | ||||
| Preoperatively | 8.74±1.98 | 8.92±2.03 | 0.607 | 0.545 |
| 6 months postoperatively | 15.11±4.35 | 16.52±3.74 | 2.385 | 0.018 |
| Muscle strength | ||||
| Preoperatively | 6.08±1.16 | 5.85±1.04 | 1.410 | 0.160 |
| 6 months postoperatively | 8.39±1.63 | 8.97±1.71 | 2.425 | 0.016 |
| Total score | ||||
| Preoperatively | 54.42±7.88 | 55.69±8.13 | 1.101 | 0.272 |
| 6 months postoperatively | 84.33±5.39 | 86.62±6.44 | 2.688 | 0.008 |
Notes: TF-A, Traditional Fluoroscopy-Assisted; 3D-P, 3D-Printed.
Pain level score
In the comparison of pain level scores between the TF-A group (n=104) and the 3D-P group (n=89), significant differences were observed at various postoperative time points. Preoperatively, there was no significant difference in pain levels between the two groups (P>0.05). However, starting from 1 week postoperatively, the 3D-P group showed significantly lower pain scores compared to the TF-A group: 1 week (P=0.002), 1 month (P=0.003), 3 months (P=0.011), and 6 months (P=0.029). These results indicate that patients treated with 3D-printed automatic resetting splints experienced significantly less pain throughout the recovery period compared to those treated with traditional fluoroscopy-assisted external fixation. The consistent reduction in pain scores suggests that the use of advanced 3D-printed technology may contribute to better pain management and improved patient comfort following tibial shaft fracture treatment (Figure 4).
Figure 4.
Comparison of Pain level score between two groups (points). Notes: TF-A, Traditional Fluoroscopy-Assisted; 3D-P, 3D-Printed; ns: no significant difference; *: P<0.05; **: P<0.01.
Discussion
This comparative study demonstrates that the use of 3D-printed automatic reset splints for the management of open tibial shaft fractures leads to improved functional recovery outcomes across multiple domains when compared to traditional fluoroscopy-assisted external fixation. The observed differences in reduction quality, healing parameters, complication rates, knee function, and pain levels collectively suggest that this innovative approach offers tangible clinical benefits.
The 3D-printed group demonstrated significantly better radiographic alignment across most parameters throughout recovery. This underscores the core technical advantage of the technology that the seamless translation of a preoperative virtual plan into physical reality. This finding strongly aligns with previous investigations into computer-assisted design and 3D printing in fracture management [20,21]. As Shin et al. suggested, the ability to simulate reduction digitally and create a patient-specific device that guides anatomical realignment minimizes the intraoperative guesswork and extensive radiation exposure inherent in traditional methods, which rely heavily on two-dimensional fluoroscopic imaging and surgeon experience [21]. Our results demonstrate that this paradigm shift, from intraoperative trial-and-error to preoperative precision planning, directly translates to superior and sustained fracture reduction. The consistent maintenance of reduction over time further suggests that 3D-printed splints provide a more stable mechanical environment, which is a critical determinant for long-term functional outcomes and lower extremity biomechanics [22,23].
Our findings indicating accelerated callus formation and shorter overall fracture healing time in the 3D-printed group suggest a positive influence on the biological aspects of fracture repair. This biological advantage can be attributed to the minimally invasive and personalized nature of the 3D-printed approach, as supported by previous reports [24,25]. The customized design, which accounts for individual anatomy and anticipated soft tissue swelling, minimizes iatrogenic soft tissue disruption and better preserves the precarious vascular supply around the tibia, a factor crucial for bone regeneration [24]. Furthermore, studies have indicated that 3D-printed orthopedic devices can be engineered to optimize the mechanical microenvironment. For instance, Li et al. highlighted that customized fixation can optimize interfragmentary strain to levels more conducive to efficient callus formation [24]. This combination of biological respect and mechanical optimization likely creates an ideal milieu for healing, explaining the significantly faster recovery times observed in our study [26].
The significantly lower overall complication rate observed with 3D-printed splints, particularly concerning pin tract infections and malunion, represents a clinically critical advancement. This reduction aligns with the findings of Qiao et al., who reported that patient-specific contouring and precise pre-planned pin placement minimize soft tissue irritation and pressure points, thereby enhancing tissue viability and reducing the risk of infection [25]. Traditional external fixators, with their standardized components, often exert uneven pressure, leading to skin necrosis and pin loosening. In contrast, the improved initial reduction and stability provided by the 3D-printed splint decrease mechanical stress on the fixation pins, reducing the primary cause of pin loosening and subsequent infection [27]. The marked reduction in malunion cases specifically validates the ability of personalized splints to maintain anatomical alignment, potentially preventing the need for corrective surgeries and their associated morbidity, as discussed in other reports on malunion treatment [28].
The superior knee function recovery and consistently lower pain levels in the 3D-printed group highlight the ultimate goal of fracture treatment: restoring quality of life. The more anatomical fracture alignment achieved through 3D printing likely restores normal biomechanics more effectively, facilitating better muscle function and joint articulation [14,29]. The reduced pain experience, evidenced by lower VAS scores at all postoperative intervals, can be attributed to the even distribution of mechanical loads by the anatomically conforming splint, minimizing pressure points [25]. This enhanced comfort, coupled with a potentially less cumbersome device that allows for better hygiene, likely improved patient adherence to rehabilitation protocols, contributing to the significantly better HSS scores [30]. Future studies might also consider assessing patient-reported outcomes and psychological benefits associated with receiving a customized, high-tech treatment [31].
While this study provides compelling evidence supporting the use of 3D-printed automatic reset splints, several limitations should be acknowledged. First, the retrospective design introduces potential for selection bias despite statistical adjustments for baseline characteristics. Second, the single-center nature of the study may limit generalizability, as surgical expertise and resource availability vary across institutions. Third, the follow-up period of six months, while adequate for assessing initial healing and early functional outcomes, may be insufficient to evaluate long-term complications and functional status, particularly regarding joint degeneration and implant-related issues. Fourth, the cost-effectiveness of this innovative approach was not evaluated in this study; the additional expenses associated with CT scanning, software, and 3D printing equipment must be weighed against the observed clinical benefits in future health economic analyses.
Future research directions should include multicenter randomized controlled trials with longer follow-up periods to confirm these findings and establish generalizability. Economic evaluations are needed to determine the cost-effectiveness of implementing 3D printing technology in orthopedic trauma care. Further technical development should focus on streamlining the design process, reducing production time, and exploring novel materials that might enhance the mechanical and biological properties of these devices. Investigation into the combination of 3D-printed splints with other advanced technologies, such as robotics4 or smart sensors that monitor healing progress, represents another promising avenue for research. Additionally, exploring the application of this technology for more complex fracture patterns or in pediatric populations would help expand its clinical utility.
Conclusion
This study demonstrates that the use of 3D-printed automatic reset splints for the treatment of tibial shaft fractures provides a clinically superior alternative to traditional fluoroscopy-assisted external fixation. The technology offers a multifaceted improvement in patient care by achieving better fracture alignment, accelerating the healing process, reducing the incidence of postoperative complications, enhancing functional recovery of the knee, and improving patient comfort through reduced pain. These benefits are likely attributable to the precision of preoperative virtual planning, the stability afforded by the patient-specific design, and the minimized soft tissue disruption. Despite the promising results, further multi-center studies with longer follow-up are warranted to confirm the long-term benefits and economic viability of this innovative approach. The integration of 3D printing technology represents a meaningful advancement toward personalized and precision medicine in orthopedic trauma care.
Acknowledgements
This study was supported by the Shenzhen Pingshan District Health Bureau and Shenzhen Pingshan District Science and Technology Innovation Bureau (No. 2024121), and the Shenzhen Science and Technology Program (No. JCYJ20210324111205015).
Disclosure of conflict of interest
None.
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