Abstract
Background
The anterior cruciate ligament (ACL) is a key structure that restricts excessive anterior translation of the tibia and maintains rotational stability. This study aims to dynamically and quantitatively assess the direct effects of ACL resection and total knee arthroplasty (TKA) on lower limb alignment and tibiofemoral joint rotation under passive, unloaded conditions and in the pathological state of osteoarthritis.
Methods
This retrospective study included 110 patients with varus knee osteoarthritis who underwent Mako for robotic-assisted TKA. Dynamic intraoperative measurements of the lower limb mechanical axis (flexion angle at maximum extension; varus angle) and tibiofemoral rotation at multiple flexion angles (min to max flexion) were recorded at three intervals: pre-ACL resection, post-ACL resection and post-TKA. The variation in rotation amplitude was calculated for successive flexion intervals.
Results
Post-ACL resection, a significant decrease in the flexion angle at the maximum extension and varus angle (both p < 0.001) was observed, which was accompanied by increased tibial internal rotation at flexion angles of 60° and above (p < 0.05). Varus alignment was successfully corrected following TKA (p < 0.001). However, tibiofemoral rotational kinematics were significantly modified: the amplitude of internal rotation decreased in the initial flexion arc (min to 30°) but increased in flexion intervals beyond 30° (all p < 0.01).
Conclusions
Under passive, unloaded osteoarthritic conditions, ACL resection immediately alters lower limb alignment and increases tibial internal rotation. Although TKA restores coronal alignment, it does not fully restore passive rotational kinematics; whether this affects active weight‑bearing function remains unknown. Accordingly, we hypothesize that rotational stability is as critical as limb alignment in TKA, pending validation with patient-reported outcome measures, functional scores and postoperative follow-up.
Keywords: Tibiofemoral rotation, Total knee arthroplasty, Anterior cruciate ligament, Robotic-assisted surgery, Lower limb alignment
Background
Total knee arthroplasty (TKA) is the definitive treatment for end-stage knee osteoarthritis (OA), a condition associated with a substantial and increasing global burden [1–3]. Physiological knee motion follows specific patterns, including the terminal extension screw-home mechanism and the medial pivot motion during flexion [4–6]. Progressive OA disrupts these native kinematics [7], which may accelerate degenerative changes, whereas prosthetic implantation and soft‑tissue release further alter postoperative knee kinematics [8–11].
In conventional TKA, the anterior cruciate ligament (ACL) is routinely resected. The ACL serves as the primary restraint to anterior tibial translation and as an important secondary stabilizer against rotational forces [12, 13]. In the osteoarthritic knee, the ACL often exhibits degenerative changes that modify its material properties [14, 15]. Therefore, its resection in this pathological environment probably has complex implications for intraoperative alignment and rotational stability.
Precise component placement is critical for coronal alignment and successful outcomes [16–20]. Component malrotation is a recognized contributor to pain, accelerated polyethylene degradation, stiffness and patellofemoral complications [16, 21–23]. A persistent challenge is the lack of objective, quantitative intraoperative criteria to assess tibiofemoral rotation that account for individual anatomy and dynamic function. Moreover, most existing evidence comes from cadaveric models that cannot fully replicate in vivo conditions, and few studies have simultaneously measured dynamic changes in mechanical alignment and tibiofemoral rotation from ACL resection to prosthesis implantation.
To address this gap, under passive, unloaded conditions and in the pathological state of osteoarthritis, we utilized the high-precision intraoperative dynamic measurement capabilities of the Mako robotic-assisted system. In a clinical TKA workflow, we aimed to comprehensively quantify the biomechanical effects of two critical stages: (1) the immediate consequence of ACL resection and (2) the overall impact of the subsequent TKA on lower limb mechanical alignment and tibiofemoral rotation across various flexion angles. We hypothesized that ACL resection would function as a discrete biomechanical event, resulting in a measurable coronal plane shift in the mechanical axis (reduced varus) alongside a decreased flexion angle at maximum extension and exacerbated tibial internal rotation. We further hypothesized that although TKA would successfully restore limb alignment, it would only partially restore the changes in tibiofemoral rotational function. These findings aim to substantiate a more integrated approach for enhancing alignment and rotation from planning through surgical execution.
Materials and methods
Patient cohort
We performed a retrospective review of patients who underwent Mako robotic-assisted TKA at our institution between January and December 2025. The inclusion criteria included patients with end-stage knee OA and varus deformity who were scheduled for Mako-assisted TKA. The exclusion criteria included (1) patients with valgus knee OA; (2) patients with preexisting ACL deficiency or a fixed flexion contracture > 15°; (3) patients with significant neuromuscular disorder (such as paralysis, myolysis or muscle weakness); (4) patients with a history of major ipsilateral knee trauma or surgery; (5) patients with posterior cruciate ligament insufficiency, inflammatory arthritis, posttraumatic arthritis, periarticular tumour or infection; and (6) patients with incomplete data. A total of 110 patients met the inclusion criteria and were evaluated across three specified intraoperative time points: pre-ACL resection, post-ACL resection and post-TKA (Fig. 1).
Fig. 1.
Flowchart of patient inclusion and analysis
Surgical protocol and data collection
All surgeries were performed by a single, high-volume arthroplasty surgeon skilled in Mako-assisted TKA (> 300 prior cases). A Triathlon cruciate-retaining (CR) fixed-bearing prosthesis (Stryker, USA) was implanted in all the patients. After preoperative computed tomography scanning for 3D model reconstruction and surgical planning (Mako Total Knee software), a medial parapatellar approach was utilized. Tracker pins were positioned extra-articularly at the medial femoral cortex and distal to the tibial tubercle for the femur and tibia, respectively. Functional alignment was adopted as the alignment technique.
After bone registration, Mako system software was used for intraoperative dynamic evaluation. Under passive, unloaded conditions, the surgeon manually directed the limb through a gravity-assisted knee flexion arc by supporting the heel with one palm and stabilizing the thigh, facilitating real-time computer-simulated measurements by the system (Fig. 2). At each stage (pre-ACL resection, post-ACL resection and post-TKA), we documented the flexion angle at maximum extension [24] and the varus/valgus angle at this point, as well as the tibiofemoral rotation angle (internal rotation positive) from maximum extension to maximum flexion at the following positions: maximum extension (min), 15°, 30°, 60°, 90°, 120° and maximum flexion (max). The variation in rotation amplitude was calculated for successive flexion intervals: min–15°, 15–30°, 30–60°, 60–90°, 90–120°, and 120°–max. Varus or internal rotation was defined as positive (+), and valgus or external rotation was defined as negative (−).
Fig. 2.
Intraoperative kinematic assessment. Under passive, unloaded conditions, the surgeon manually guides the limb through a gravity-assisted knee flexion arc by supporting the heel with one palm while stabilizing the thigh, allowing for real-time computer-simulated measurements by the system
Statistical analysis
Data were analysed using the Statistical Package for the Social Sciences 26.0 (IBM, Armonk, New York, USA). Continuous variables are presented as the mean ± standard deviation (SD); categorical variables are presented as frequencies (percentages). The normality of the data was assessed using the Kolmogorov‒Smirnov test. For the comparison of continuous variables at different surgical stages, if the data followed a normal distribution, the paired sample t-test was used; for non-normal data, the Wilcoxon signed-rank test was employed. p < 0.05 was considered to indicate statistical significance.
Results
Patient demographics
The mean age of the 110 patients was 70.62 ± 7.05 years (52–88), and the mean body mass index was 26.23 ± 3.37 kg/m2. There were 23 males (20.9%) and 87 females (79.1%), with 56 right knees (50.9%) and 54 left knees (49.1%). The varus angle before anterior cruciate ligament resection was 5.91° ± 3.83° (0°–14°) (Table 1).
Table 1.
Demographic details and baseline characteristics of the study cohort
| Parameter | Outcome (n = 110) |
|---|---|
| Age (years) | 70.62 ± 7.05(52–88) |
| Gender | |
| Male | 23(20.9%) |
| Female | 87(79.1%) |
| Operation side | |
| Right | 56(50.9%) |
| Left | 54(49.1%) |
| BMI (kg/m2) | 26.23 ± 3.37 |
| K–L grade | |
| 3 | 48(43.6%) |
| 4 | 62(56.4%) |
| ASA | |
| 2 | 53(48.2%) |
| 3 | 57(51.8%) |
| Varus angle (Pre-ACL resection) (°) | 5.91 ± 3.83 (0–14) |
BMI, body mass index; K–L, Kellgren–Lawrence; ASA, American Society of Anaesthesiologists; ACL, anterior cruciate ligament
Immediate effects of ACL resection (pre‑ versus post‑ACL resection)
ACL resection induced significant immediate changes (Table 2). Both the flexion angle at maximum extension (5.34° ± 3.95° versus 3.79° ± 4.06°, p < 0.001) and the varus angle (5.91° ± 3.83° versus 5.41° ± 3.65°, p < 0.001) decreased significantly.
Table 2.
Effect of ACL resection on lower limb alignment and tibiofemoral rotation: comparison between pre‑resection and post‑resection measurements
| Parameter (°) | Pre-ACL resection | Post-ACL resection | p |
|---|---|---|---|
| Flexion angle at maximum extension (°) | 5.34 ± 3.95 | 3.79 ± 4.06 | < 0.001 |
| Varus angle‡ (°) | 5.91 ± 3.83 | 5.41 ± 3.65 | < 0.001 |
| Tibiofemoral rotation angle‡ (°) | |||
| Min | −8.66 ± 5.49 | −8.56 ± 6.30 | 0.696 |
| 15° | −5.80 ± 5.61 | −5.49 ± 6.41 | 0.191 |
| 30° | −4.24 ± 6.23 | −3.66 ± 6.88 | 0.090 |
| 60° | −3.47 ± 6.47 | −2.48 ± 6.82 | 0.041 |
| 90° | −1.34 ± 5.94 | −0.13 ± 6.75 | 0.008 |
| 120° | 2.91 ± 5.44 | 3.92 ± 5.93 | 0.008 |
| Max | 4.08 ± 5.03 | 5.10 ± 5.04 | 0.004 |
ACL, anterior cruciate ligament
‡, varus or internal rotation was defined as positive (+), and valgus or external rotation as negative (−)
Tibiofemoral rotation did not change at lower flexion angles (min, 15°, 30°; all p > 0.05). However, at higher flexion angles, significant increases in internal rotation were observed after ACL resection: at 60° (−3.47° ± 6.47° versus −2.48° ± 6.82°, p = 0.041), 90° (−1.34° ± 5.94° versus −0.13° ± 6.75°, p = 0.008), 120° (2.91° ± 5.44° versus 3.92° ± 5.93°, p = 0.008) and maximum flexion (4.08° ± 5.03° versus 5.10° ± 5.04°, p = 0.004) (Table 2, Fig. 3a). The amplitude of rotational change across consecutive flexion intervals was not significantly affected at this stage (Table 3, Fig. 4).
Fig. 3.
Navigated kinematic changes during Mako robotic-assisted TKA. a Compared with the pre-ACL resection state, tibial internal rotation was significantly greater at 60°, 90°, 120° and max after ACL resection (p < 0.05). b Post-TKA, compared with the pre-ACL resection state, tibial internal rotation differed significantly at min, 15°, 30°, 90°, 120° and max (p < 0.05). c Post-TKA, compared with the post-ACL resection state, tibial internal rotation differed significantly at min, 30°, 90°, 120° and max (p < 0.05)
Table 3.
Influence of ACL resection on the variation of tibiofemoral rotation amplitude: pre‑resection versus post‑resection
| Tibiofemoral rotation angle‡ (°) | Pre-ACL resection | Post-ACL resection | p |
|---|---|---|---|
| Min–15° | 2.86 ± 4.26 | 3.08 ± 3.55 | 0.481 |
| 15–30° | 1.56 ± 2.94 | 1.82 ± 3.22 | 0.520 |
| 30–60° | 0.76 ± 3.01 | 1.19 ± 2.74 | 0.059 |
| 60–90° | 2.14 ± 2.92 | 2.35 ± 3.20 | 0.805 |
| 90–120° | 4.25 ± 3.49 | 4.05 ± 2.92 | 0.570 |
| 120°–max | 1.16 ± 3.30 | 1.18 ± 2.64 | 0.854 |
ACL, anterior cruciate ligament
‡, varus or internal rotation was defined as positive (+), and valgus or external rotation as negative (−)
Fig. 4.
Amplitude of change in tibial internal rotation across consecutive flexion intervals at different surgical stages. No significant difference was observed in the amplitude of rotational change before versus after ACL resection (p > 0.05). Post-TKA, the amplitude of internal rotation decreased in the min–15° and 15–30° intervals (p < 0.001) but increased in the 30–60°, 60–90°, 90–120° and 120°–max intervals (p < 0.01) compared with the pre- and post-ACL resection states
Effects of TKA compared with pre‑ACL resection (pre‑ACL versus post‑TKA)
Relative to the pre‑ACL resection state, TKA successfully corrected coronal alignment. The final varus angle significantly decreased (3.35° ± 2.09° versus 5.91° ± 3.83°, p < 0.001), whereas the flexion angle at maximum extension also decreased (4.17° ± 1.67° versus 5.34° ± 3.95°, p = 0.015) (Table 4).
Table 4.
Effect of TKA on lower limb alignment and tibiofemoral rotation: comparison between pre‑ACL resection and post‑TKA
| Parameter (°) | Pre-ACL resection | Post-TKA | p |
|---|---|---|---|
| Flexion angle at maximum extension (°) | 5.34 ± 3.95 | 4.17 ± 1.67 | 0.015 |
| Varus angle‡ (°) | 5.91 ± 3.83 | 3.35 ± 2.09 | < 0.001 |
| Tibiofemoral rotation angle‡ (°) | |||
| Min | −8.66 ± 5.49 | −5.91 ± 5.27 | < 0.001 |
| 15° | −5.80 ± 5.61 | −5.05 ± 5.23 | 0.041 |
| 30° | −4.24 ± 6.23 | −5.39 ± 5.71 | 0.008 |
| 60° | −3.47 ± 6.47 | −3.56 ± 5.86 | 0.951 |
| 90° | −1.34 ± 5.94 | 0.18 ± 5.57 | 0.004 |
| 120° | 2.91 ± 5.44 | 5.55 ± 6.63 | < 0.001 |
| Max | 4.08 ± 5.03 | 7.65 ± 6.47 | < 0.001 |
TKA, total knee arthroplasty; ACL, anterior cruciate ligament
‡, varus or internal rotation was defined as positive (+), and valgus or external rotation as negative (−)
The tibiofemoral rotational profile was significantly modified throughout the flexion arc, except at 60° (Table 4, Fig. 3b). Significant differences in rotation were observed at min, 15°, 30°, 90°, 120° and max (all p < 0.05). Moreover, the amplitude of rotational change within each flexion interval was significantly altered after TKA across all the measured intervals (all p < 0.01) (Table 5, Fig. 4).
Table 5.
Influence of TKA on the variation of tibiofemoral rotation amplitude: pre‑ACL resection versus post‑TKA
| Tibiofemoral rotation angle‡ (°) | Pre-ACL resection | Post-TKA | p |
|---|---|---|---|
| Min–15° | 2.86 ± 4.26 | 0.86 ± 2.02 | < 0.001 |
| 15–30° | 1.56 ± 2.94 | -0.34 ± 2.18 | < 0.001 |
| 30–60° | 0.76 ± 3.01 | 1.84 ± 2.15 | 0.001 |
| 60–90° | 2.14 ± 2.92 | 3.74 ± 2.77 | < 0.001 |
| 90–120° | 4.25 ± 3.49 | 5.36 ± 3.30 | 0.006 |
| 120°–max | 1.16 ± 3.30 | 2.10 ± 2.64 | 0.005 |
TKA, total knee arthroplasty; ACL, anterior cruciate ligament
‡, varus or internal rotation was defined as positive (+), and valgus or external rotation as negative (−)
Effects of TKA compared with post‑ACL resection (post‑ACL versus post‑TKA)
When the post‑TKA state was compared with the post‑ACL resection state (Table 6), the flexion angle at maximum extension was not significantly different, whereas the varus angle was significantly lower (3.35° ± 2.09° versus 5.41° ± 3.65°, p < 0.001).
Table 6.
Comparison of lower limb alignment and tibiofemoral rotation between post‑ACL resection and post‑TKA
| Parameter (°) | Post-ACL resection | Post-TKA | p |
|---|---|---|---|
| Flexion angle at maximum extension (°) | 3.79 ± 4.06 | 4.17 ± 1.67 | 0.235 |
| Varus angle‡ (°) | 5.41 ± 3.65 | 3.35 ± 2.09 | < 0.001 |
| Tibiofemoral rotation angle‡ (°) | |||
| Min | −8.56 ± 6.30 | −5.91 ± 5.27 | < 0.001 |
| 15° | −5.49 ± 6.41 | −5.05 ± 5.23 | 0.245 |
| 30° | −3.66 ± 6.88 | −5.39 ± 5.71 | < 0.001 |
| 60° | −2.48 ± 6.82 | −3.56 ± 5.86 | 0.003 |
| 90° | −0.13 ± 6.75 | 0.18 ± 5.57 | 0.661 |
| 120° | 3.92 ± 5.93 | 5.55 ± 6.63 | < 0.001 |
| Max | 5.10 ± 5.04 | 7.65 ± 6.47 | < 0.001 |
TKA, total knee arthroplasty; ACL, anterior cruciate ligament
‡, Varus or internal rotation was defined as positive (+), and valgus or external rotation as negative (−)
The tibiofemoral rotational profile was significantly modified throughout the flexion arc, except at 15° and 90° (Table 6, Fig. 3c). Significant differences in rotation were observed at min, 30°, 60°, 120° and max (all p < 0.05). Furthermore, the amplitude of rotational change across consecutive flexion intervals significantly differed after TKA compared with the post‑ACL resection state for all intervals (all p < 0.05) (Table 7, Fig. 4).
Table 7.
Comparison of the variation of tibiofemoral rotation amplitude between post‑ACL resection and post‑TKA
| Tibiofemoral rotation angle‡ (°) | Post-ACL resection | Post-TKA | p |
|---|---|---|---|
| Min–15° | 3.08 ± 3.55 | 0.86 ± 2.02 | < 0.001 |
| 15–30° | 1.82 ± 3.22 | -0.34 ± 2.18 | < 0.001 |
| 30–60° | 1.19 ± 2.74 | 1.84 ± 2.15 | 0.015 |
| 60–90° | 2.35 ± 3.20 | 3.74 ± 2.77 | < 0.001 |
| 90–120° | 4.05 ± 2.92 | 5.36 ± 3.30 | 0.001 |
| 120°–max | 1.18 ± 2.64 | 2.10 ± 2.64 | 0.002 |
TKA, total knee arthroplasty; ACL, anterior cruciate ligament
‡, varus or internal rotation was defined as positive (+), and valgus or external rotation as negative (−)
Discussion
Under passive, unloaded and anaesthetized conditions in patients with varus knee OA, our findings revealed that ACL resection promptly reduced varus alignment, decreased the flexion angle at maximum extension and exacerbated tibial internal rotation at mid-to-deep flexion angles. Subsequent Mako robotic‑assisted TKA successfully corrected coronal alignment. These results confirmed that ACL resection is a distinct intraoperative event with measurable biomechanical consequences and that current TKA techniques do not completely restore preoperative rotational kinematics in this passive setting. The potential relevance of these kinematic alterations to active, weight‑bearing function requires further investigation.
The ACL is the primary structure that limits the forwards displacement of the tibia and serves as an essential secondary restraint to internal/external rotation [12, 13]. The two functional bundles, the anteromedial (taut in flexion) and posterolateral (taut in extension), provide this stability [12]. Previous studies have shown that in TKA, ACL resection does not affect the knee’s flexion angle at maximum extension [25]. However, our results revealed an increase in this angle (Table 2). In varus OA knees, the ACL may contribute to soft-tissue balance, countering medial tightness. ACL removal may partially explain the immediate decrease in varus angulation observed. Furthermore, the ability of the ACL to limit internal rotation is well established in the context of injury [26, 27]. Our data enhanced this understanding within the intraoperative setting, demonstrating that resection directly exacerbated internal rotation at elevated flexion angles (Table 2).
Healthy knees generally exhibit 1–20° internal tibial rotation during flexion [28–30]. In our patients, compared with pre-resection, TKA modified this pattern: internal rotation progressively diminished during early flexion (0–30°) but seemed to increase during later flexion (Tables 5 and 7). However, the general pattern deviates from the physiological model. This finding corresponds with the findings in the literature indicating that axial rotation is typically more limited following TKA, regardless of the implant design used [31, 32]. However, whether this change in pattern and the difference in the rotational amplitude of the tibiofemoral joint (Tables 5 and 7) have clinical significance still requires support from subsequent patient-reported outcome measures (PROMs), functional scores or postoperative follow-up results.
A critical consideration is that our intraoperative measurements were obtained under passive, anaesthesia‑induced, non‑weight‑bearing conditions. The tibial rotation pattern is highly dependent on joint load and muscle activity. Under conditions of weight-bearing and dynamic activities, active muscle strength and ground reaction force alter the kinematics of the tibiofemoral joint [33–35]. The relationship between ACL deficiency and altered tibiofemoral rotation has also been investigated under dynamic, weight‑bearing conditions. Excessive tibial rotation has been documented in ACL-deficient knees during walking, and ACL injury significantly increases tibiofemoral rotation as running speed increases [36, 37]. Therefore, the increased tibial internal rotation observed after ACL resection and the modified rotational pattern after TKA in our passive setting could not be directly equated to functional impairment during gait or other weight‑bearing activities. Future research will need to integrate the passive measurement results during the operation with postoperative dynamic and weight-bearing assessments, as well as PROMs, to determine the clinical significance of these intraoperative rotational changes.
Impaired rotational kinematics are increasingly associated with patient dissatisfaction and functional limitations following TKA. Abnormal rotation may lead to pain, uneven polyethylene wear and patellofemoral complications [16, 21–23] and can complicate the intraoperative balancing process, potentially resulting in mid-flexion instability or restricted motion [22]. Consequently, achieving rotational alignment that approximates native kinematics under passive conditions should be regarded as essential for restoring the coronal plane mechanical axis, acknowledging that passive rotational alignment may not fully capture functional performance under load. Further verification through PROMs, functional scores and postoperative follow-up is needed.
This field has witnessed advancements such as the use of medial-pivot prosthesis geometries [38–41], bicruciate-retaining/substituting designs [32, 42–46] and kinematic alignment techniques [47–49]. Despite these advancements, consistent and significant improvement in postoperative axial rotation has been difficult to demonstrate clinically [31, 32]. This disconnection suggests that elements beyond component design or the coronal alignment strategy influence postoperative rotation. Knee rotation under load results from complex interactions between the bony anatomy, articular surface geometry and the combined tension of all ligamentous structures, including the ACL. Imitating an isolated kinematic feature may thus be inadequate to restore the dynamic, system-wide coordination of the native joint. A comprehensive understanding of how specific surgical steps, such as ACL resection, disturb this system is essential for formulating more effective solutions.
Our study has two primary clinical implications. First, this study specifically investigated varus OA of the knee, characterized by a pre-existing soft-tissue imbalance. Here, ACL resection eliminates a potentially crucial stabilizing component, an impact that may be undervalued. Second, through the application of robotic technology for dynamic intraoperative measurement, we successfully quantified the effects of ACL resection and delineated the subsequent impact of TKA. This objective, data-driven approach enhances our understanding of procedural biomechanics and highlights the significance of this technology in optimizing surgical techniques.
Limitations
This study has several limitations. The kinematic data were obtained under passive, non-weight-bearing conditions with anaesthesia, which may not accurately represent active, loaded function. This single-centre, observational study lacks long-term clinical follow-up, preventing a direct correlation between our intraoperative measures and final patient-reported outcomes or implant longevity. Our findings pertain exclusively to a fixed-bearing CR prosthesis implanted using a specific robotic system; extrapolation to alternative designs or techniques requires validation. This study highlights the need for increased awareness of potential rotational alterations, especially in complex cases involving severe deformity or ligament deficiency, necessitating additional targeted research.
Conclusions
Under passive, unloaded and anaesthetized conditions, this study revealed that ACL resection during TKA results in deviation in lower extremity alignment and intensifies a pattern of increased tibial internal rotation at greater flexion angles. Although subsequent robotic‑assisted TKA effectively rectifies coronal malalignment, it fails to completely restore preoperative tibiofemoral rotational kinematics under these passive conditions. Whether these passive kinematic alterations affect active, weight‑bearing function remains to be determined. These results highlight that attaining optimal long‑term outcomes in TKA may necessitate a surgical philosophy that intentionally considers limb alignment and rotational stability as interrelated objectives, while recognizing that this hypothesis requires validation through clinical studies with PROMs, functional scores and postoperative follow-up.
Acknowledgements
We would like to give our sincere appreciation to the reviewers for their helpful comments on this article.
Author contributions
Yongyong Fan: design of investigation and data collection. Shujun Chen: data analysis and writing paper. Lingjun Jiang: data analysis. Zhongyi Chen: data collection and data analysis. Mingjiao Wu: data collection, data analysis and writing paper. Chenglong Wang: design of investigation, data collection, data analysis and writing paper. All authors read and approved the final manuscript.
Funding
This study was supported by Taizhou Science and Technology Plan (Project No. 25ywb62), Zhejiang Science and Technology Plan for Disease Prevention and Control (Project No. 2026JKY312) and Zhejiang Science and Technology Plan for Health Commission (Project No. 2025HY1427).
Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
This study has been approved by the Ethics Committee (Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University) (December 25, 2025, Approval number K20251230). All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Written informed consent was obtained from individual or guardian participants.
Consent for publication
Not applicable.
Informed consent
Written informed consent was obtained from all patients.
Competing interests
The authors declare that they have no competing interests.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Yongyong Fan, Shujun Chen and Lingjun Jiang have contributed equally to this work.
Contributor Information
Zhongyi Chen, Email: czy@enzemed.com.
Mingjiao Wu, Email: wumj2501@enzemed.com.
Chenglong Wang, Email: wangcl4779@enzemed.com.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.