Association of Computer-Assisted Virtual Preoperative Planning With Postoperative Mortality and Complications in Older Patients With Intertrochanteric Hip Fracture

Key Points Question Is preoperative planning using computer-assisted virtual surgical technology associated with decreases in the risks of all-cause 90-day mortality and postoperative complications among older patients with intertrochanteric hip fractures? Findings In this cohort study of 1221 older patients with intertrochanteric hip fractures, the use of computer-assisted virtual preoperative planning among a propensity score–matched cohort was associated with a lower incidence of 90-day mortality and postoperative complications compared with the use of conventional preoperative planning. Meaning This study’s findings suggest that preoperative planning using computer-assisted virtual surgical technology for older patients with intertrochanteric hip fractures is associated with decreases in the risks of all-cause 90-day mortality and postoperative complications.


Introduction
Hip fractures are the most common type of fracture in patients older than 50 years. 1,2More than 300 000 hip fractures occur in the US each year. 2,3With the aging of the population, it is estimated that by 2040, the annual number of hip fractures will double. 3,4It has been reported that nearly one-half of hip fractures occur in the intertrochanteric region, 4 and the outcomes of intertrochanteric hip fractures are worse if the fractures are left untreated.Therefore, early surgical intervention in patients with intertrochanteric fractures remains the standard of treatment.
However, the postoperative outcomes are unsatisfactory owing to a higher risk of mortality, functional worsening, and diminished quality of life, which may impose a burden on health care systems. 5,6Unfortunately, most risk factors (including age, sex, and comorbidities) associated with worse postoperative outcomes in patients with intertrochanteric fractures are not modifiable. 7e unsatisfactory postoperative outcomes for patients with intertrochanteric fractures represent an opportunity to improve the treatment of this injury, and effective preoperative planning may provide a means to do so.Conventional preoperative planning has been performed using a combination of imaging data and the surgeon's experience, which is the standard method used by most orthopedic surgeons in clinical settings.2][13] The benefits observed in preoperative planning using virtual surgical technology may be owing to the fact that this approach allows surgeons to observe fracture characteristics, such as the direction of the fracture line, the size of the fracture, and the number and location of fragments.In addition, surgeons can perform the operation virtually 11,14 To our knowledge, no data exist to recommend 1 type of preoperative planning over another for the treatment of intertrochanteric fractures.Therefore, the aim of this retrospective cohort study was to investigate whether preoperative planning using computer-assisted virtual surgical technology was associated with decreases in the risks of mortality and postoperative complications and improvements in postoperative functional outcomes.A secondary aim was to examine whether the junior surgical residents, through the use of virtual surgical planning, would experience a faster learning curve regarding the treatment of these fractures.

Data Sources and Study Population
This study was a retrospective cohort analysis using information obtained from the electronic medical record database of East Hospital, Tongji University School of Medicine, a level 1 trauma JAMA Network Open | Orthopedics center in Shanghai, China.The database contains patient data that include population characteristics at hospital admission, injury details, and surgical notes.The postoperative data of patients were obtained from the follow-up records.The study was approved by the institutional review board of East Hospital, Tongji University School of Medicine, with a waiver of informed consent because all data were deidentified.This study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cohort studies.
We identified all patients 65 years and older on the date of hospital admission who had an intertrochanteric hip fracture and were treated with the proximal femoral nail antirotation 2 (PFNA-II, which has a smaller medial lateral angle and is more appropriately designed for the Asian population compared with the original PFNA) technique between January 1, 2009, and March 31, 2018.Patients who had multiple traumatic injuries, bilateral intertrochanteric hip fractures, pathological fractures, fractures that occurred during an inpatient hospital stay, previous fractures or surgery performed on the currently fractured site, and patients who transferred to another hospital after surgery or discharged from the hospital against medical advice were excluded.
A total of 1445 patients who underwent surgery for intertrochanteric hip fractures were identified.Of those, 224 patients (93 patients in the virtual planning group and 131 patients in the conventional planning group) were excluded because they met 1 or more of the following exclusion criteria: follow-up period of less than 1 year (126 patients [56.3%]), repeated fracture or surgery on the currently fractured site (42 patients [18

Exposure Variable
The exposure was the type of preoperative planning received by patients with intertrochanteric fractures, which comprised either planning using conventional methods or planning using computerassisted virtual surgical technology.In the conventional planning group, preoperative planning was based on plain radiographic images and computed tomographic scans, including 2-dimensional and/or 3-dimensional (3-D) volume-rendering imaging, of the injured limb along with the surgeon's experience, which is the standard method used by most orthopedic surgeons.In the virtual planning group, computed tomographic scans, which were obtained using a 16-detector spiral scanner (GE LightSpeed 16; GE Medical Systems), were entered into a computer-assisted orthopedic clinical research platform (SuperImage system, orthopedic edition 1.1; Cybermed). 11,15A 3-D image of the fracture in the proximal femur was reconstructed using a surface-shaded display algorithm, and fracture fragments were marked with distinct colors (Figure 1).The reduction of fracture procedure was simulated (Figure 1), and the suitable size of intramedullary devices in the PFNA-II system (including the length and diameter of the main nail, spiral blade, and distal locking screw) was chosen (Figure 1).
The surgical procedures were performed by our surgery team, which included 2 junior surgical residents (who began performing operations for intertrochanteric fractures in January 2009) and several senior surgeons (with more than 20 years of experience in performing operations for intertrochanteric fractures, including Y.C.).When a junior surgical resident performed the surgery, the operation was closely supervised by faculty.All surgical procedures were performed in accordance with the standard process and preoperative planning method.

Outcomes
The primary outcomes were all-cause mortality and postoperative complications (including myocardial infarction, heart failure, stroke, kidney failure, and sepsis) within 90 days after the surgery.The primary outcomes were identified based on outpatient and/or telephone records.The secondary outcome was use of the health care system owing to postoperative complications, which The VAS is used to measure the intensity of pain using a numerical rating scale (score range, 0-10 points, with 0 indicating no pain and 10 indicating maximum pain).

Learning Curve
Patients who received treatment from junior surgical residents and who had data available regarding the duration of the closed reduction procedure, the duration of surgery, the number of fluoroscopic images performed, the estimated amount of blood loss, and the conversion rates to open reduction procedures were used to evaluate the learning curve.The duration of the closed reduction of fracture procedure was recorded as the time from the beginning of the reduction procedure to disinfection.
The duration of surgery was recorded as the time from skin incision to closure.
The number of fluoroscopic images performed was recorded as the count of fluoroscopic images taken from the beginning of the reduction procedure to the end of the surgery.The estimated amount of blood loss was recorded as the amount of bleeding (measured in mL) that occurred during the surgery.For complex intertrochanteric hip fractures in which it was difficult to insert the guide pin during surgery, open reduction and internal fixation procedures were performed.Therefore, the conversion rates to open reduction procedures were also recorded to analyze the learning curve.

Statistical Analysis
To balance the potential differences in baseline characteristics between the 2 groups, propensity score matching was performed.The propensity score was estimated using logistic regression analysis based on the patient's sociodemographic characteristics, functional status before injury, mechanism of injury, affected side of hip, fracture classification, timing of surgery, medical history, year of surgery, and status according to the American Society of Anesthesiologists (ASA) Physical Status Classification System (which assesses a patient's medical comorbidities before anesthesia; status range, ASA 1 to ASA 6, with ASA 1 indicating a healthy patient with no disease, ASA 2 indicating a patient with mild systemic disease, ASA 3 indicating a patient with severe systemic disease, ASA 4 indicating a patient with severe systemic disease that is life-threatening, ASA 5 indicating a patient who is not expected to survive without surgery, and ASA 6 indicating a patient in whom brain death has occurred; higher ASA status indicates greater risk during anesthesia).One-to-one nearestneighbor caliper matching was used to match patients based on the logit function of the propensity score using a caliper equal to 0.02 of the SD of the logit function of the propensity score. 17Patients were exactly matched according to the baseline timing of surgery.
For a given covariate, a standardized difference of less than 10% indicates a relatively small imbalance. 18The balance of baseline characteristics was also assessed in patients with and without early surgery (Յ24 hours after injury and >24 hours after injury, respectively) because the comparisons between patients in the virtual planning group and the conventional planning group were stratified by the occurrence of early surgery.
A Cox proportional hazards regression analysis was used to compare patients in the virtual planning group with those in the conventional planning group for all-cause 90-day mortality in the propensity score-matched cohort, with robust sandwich estimates used to account for the clustering within matched sets. 19For the end point of 90-day postoperative complications, a competing risk analysis was performed to construct cumulative incidence function curves, and the difference between the 2 groups was evaluated using the Fine and Gray test. 20The proportional hazards assumption was examined using the Schoenfeld residuals test. 21Poisson regression analysis was used to assess complication-associated outpatient visits, reoperations, and readmissions.Subgroup

Study Population
Among 1221 patients who underwent hip surgery, the mean (SD) age was 73.  1).
Propensity score matching produced 407 patient pairs.All baseline characteristics were balanced between the 2 groups (Table 1), and standardized differences in baseline characteristics did not exceed 10%.Of the 814 patients matched by propensity score, 440 patients (54.1%) underwent early surgery.Baseline characteristics stratified by early surgery are reported in eTable 1 and eTable 2 in the Supplement.In patients who did and did not receive early surgery, the baseline characteristics were balanced between those in the virtual planning group and those in the conventional planning group.when comparative analyses were performed between patients in the virtual planning group and the conventional planning group (eTable 7 and eTable 8 in the Supplement).

Learning Curve
A total of 277 patients in the virtual planning group and 281 patients in the conventional planning group received treatment from junior surgical residents.Patient demographic characteristics were evaluated to monitor selection bias (eTable 9 and eTable 10 in the Supplement).Significant improvements in the duration of surgery were observed after 50 cases (mean [SD], 64.2 [3.5]   minutes for cases 1-50 vs 52.P < .001) in the conventional planning group.Figure 2 shows the learning curves for surgery duration in the 2 groups (in the virtual planning group, y = −0.000001x 3 + 0.0008x 2 − 0.2023x + 68.082; R 2 = 0.7155; P < .001for cubic regression; in the conventional planning group, y = 7E -07x 3 -0.0003x 2 -0.0303x + 65.762; R 2 = 0.7322; P < .001for cubic regression).The learning curve for surgery duration in the virtual planning group was faster and reached the platform stage (ie, the point at which the surgery duration could not be reduced further) earlier compared with that of the conventional planning group (Figure 2).

Discussion
In this retrospective cohort study of patients with intertrochanteric hip fractures, the receipt of preoperative planning based on computer-assisted virtual surgical technology compared with conventional methods was associated with a lower risk of mortality, postoperative complications, and reoperations within 90 days after surgery.However, the benefits of virtual surgical technology were not observed for complication-associated outpatient visits, hospital readmissions, and functional outcomes.The learning curve for surgical residents who performed operations in the virtual planning group was faster than that of surgical residents who performed operations in the conventional planning group.
The benefits of computer-assisted virtual preoperative planning for mortality, postoperative complications, and reoperations may be associated with several factors.First, for complex intertrochanteric hip fractures, virtual planning allows surgeons to observe the characteristics and injury details of fracture fragments (such as fracture line orientation, size, and number and position of fragments) from multiple perspectives before performing surgery and to evaluate the possibility of reduction for each fragment.Second, by using a preoperative simulation of the reduction procedure, surgeons can assess the important anatomical landmarks of reduction and the integrity of the lateral femoral wall, identify the key fracture fragments that need to be restored, and evaluate whether a bone defect is present after the reduction procedure.Third, surgeons can simulate the implantation of internal fixation devices before performing surgery to obtain reliable information about the appropriate size of the device.The acquisition of this detailed information is conducive to achieving fracture reduction and implanting internal fixation devices rapidly and accurately during surgery.This information may also reduce the duration of intraoperative reduction procedures and the number of fluoroscopic images performed, which can decrease the duration of surgery and the amount of intraoperative blood loss and improve the success rate of reduction and fixation procedures.
The advantages observed in the virtual planning group may be associated with the faster learning curve for surgical resident using computer-assisted virtual surgical technology compared with conventional methods.In addition, the computer-assisted preoperative planning system is efficient and convenient.In this study, the mean duration of virtual preoperative planning was approximately 27.0 minutes.The computer-assisted preoperative planning was completed in a software system, in which surgeons could easily and accurately control the 3-D surface reconstruction image based on computed tomographic scanning data and could complete the free segmentation and free editing of the 3-D image of each fracture fragment (such as the movement and reduction of the fragment) in a few minutes.In addition, the appropriate internal fixation devices could be selected for virtual implantation.
The benefits observed in the virtual planning group were present among patients who received early surgery but not among those who received delayed surgery.A hip fracture is often associated with traumatic injury, pain, bleeding, and immobility.These factors initiate inflammatory, hypercoagulable, stress-associated, and catabolic states that have the potential to produce complications, such as myocardial infarction, pulmonary embolism, pneumonia, sepsis, stroke, major bleeding, disability, and mortality. 22,23It is possible to minimize a patient's exposure to these harmful factors through early surgery. 22,24Therefore, the potential harms of delaying surgery may offset the benefits of preoperative planning using computer-assisted virtual surgical technology.No significant differences were found between the virtual planning group and the conventional planning group with regard to outpatient visits, hospital readmissions, and functional outcomes.The function and status of patients discharging from the hospital were associated with the subsequent

Limitations
This study has several limitations.First, given its retrospective observational design, there was the potential for selection bias and confounding bias.Therefore, propensity score matching and regression analyses were used to obtain well-balanced groups.Despite the performance of procedures to minimize selection and confounding biases, the possibility of residual confounding (ie, the presence of comorbid factors that were not measured by the data available for analysis) remained.The presence of unmeasured comorbidities in patients with intertrochanteric hip fractures may have had implications for the study's outcomes.Thus, further research is needed through a larger randomized prospective study.
Second, with the exception of experience with intertrochanteric hip fractures, it was not clear whether differences existed in the experience of the 2 junior surgical residents and the senior surgeons with regard to other types of fractures.These differences may have had implications for their treatment of intertrochanteric hip fractures.However, in China, junior surgical residents are not permitted to perform operations without consultant supervision.Furthermore, the PFNA-II technique is generally less invasive than other methods and is a relatively simple surgery to perform.
Therefore, even if differences existed between the 2 junior surgical residents and the senior surgeons regarding their experience with other types of fractures, the implications for our results may be minimal.
Third, we were not able to adjust our analyses for any medical circumstances that may have been factors in the postoperative outcomes of patients discharging from the hospital.However, patients who received treatment from our research team participated in standard rehabilitation programs during the follow-up period.Therefore, the medical circumstances at discharge for postoperative outcomes would have been controlled.Fourth, when evaluating the differences in postoperative functional outcomes between the 2 groups, death was considered the appropriate censoring point, which likely produced bias in the results.To evaluate the implications of this bias, the mean score of the group with the lower function score was used as the score of the patients who had died; thus, the data were supplemented.The data indicated that the results were consistent with those before supplementation, and no significant difference was observed.

Conclusions
Among older patients with intertrochanteric hip fractures who received preoperative planning, the use of computer-assisted virtual surgical technology was associated with decreases in the risks of 90-day mortality, postoperative complications, and reoperations compared with the use of conventional methods.Virtual preoperative planning was also associated with a faster learning curve for junior surgical residents compared with conventional planning.However, the benefits of virtual planning were not found for outpatient visits, hospital readmissions, and functional outcomes.These findings support the use of preoperative planning based on computer-assisted virtual surgical technology for older patients with intertrochanteric fractures.Further studies are needed to define the role of virtual surgical technology.

Figure 1 .D
Figure 1.Application of Computer-Assisted Virtual Surgical Technology for Preoperative Planning in a Patient With Intertrochanteric Hip Fracture Anteroposterior view of plain radiographA analyses for 90-day mortality and postoperative complications were stratified by age, sex, functional status before injury, ASA status, AO Foundation/Orthopaedic Trauma Association fracture classification (classification range, A1 to A3, with A1 indicating simple fracture, A2 indicating comminuted fracture involving the lateral cortex, and A3 indicating reverse oblique fracture), and the presence of anemia, atrial fibrillation, chronic kidney disease, heart failure, intracranial bleeding, and myocardial infarction.The consistency of hazard ratios (HRs) across subgroups was tested by the significance of the interaction terms, and the subgroup analyses were regarded as exploratory.The baseline characteristics of patients are potential confounding factors for assessing postoperative functional outcomes.Therefore, a multivariable linear regression analysis was performed to compare the differences in functional outcomes (including the Harris hip score, the SF-36 PCS score, and the VAS score) between the 2 groups.Outcomes of the learning curve were reviewed in groups of 25 cases to minimize the consequences of demographic differences and to optimize normalcy in distribution.To account for confounding factors, a multivariable linear JAMA Network Open | Orthopedics regression analysis was used to evaluate the changes in the learning curve for the duration of the closed reduction procedure, the duration of surgery, the number of fluoroscopic images performed, and the estimated amount of blood loss, and a logistic regression analysis was performed for the conversion rate to open reduction procedures.Baseline variables that were considered clinically relevant or that had a P value less than .10 on the univariate analysis were entered into the regression model.Variables for inclusion were carefully chosen, given the number of incidents available, to ensure parsimony of the final model.All tests were paired and 2-sided, with a significance threshold of P < .05.All statistical analyses were performed using Stata software, version 14.1 (StataCorp LLC) and SAS software, version 9.4 (SAS Institute Inc).Data were analyzed from April 5 to October 5, 2019.
The duration of the closed reduction of fracture procedure indicated a significant improvement after 50 cases (mean [SD], 33.2[3.3]minutes for cases 1-50 vs 23.0[2.4]minutes for cases 51-277; P < .001) in the virtual planning group and after 75 cases (mean [SD], 35.0 [3.0] minutes for cases 1-75 vs 23.5[2.7]minutes for cases 76-281; P < .001) in the conventional planning group.The number of fluoroscopic images performed and the estimated amount of blood loss indicated substantial decreases after 50 cases in the virtual planning group and 100 cases in the conventional planning group.The learning curve for the duration of the closed reduction procedure, the number of fluoroscopic images performed, and the estimated amount of blood loss among surgical residents performing operations in the virtual planning group was faster and reached the platform stage earlier compared with the learning curve of surgical residents performing operations in the conventional planning group (eFigure 3, eFigure 4, and eFigure 5 in the Supplement).A similar improvement in the

Table 1 .
Baseline Demographic Characteristics of Patients Before and After Propensity Score Matching Based on Type of Preoperative Planning 30 person-days in the conventional planning group; IRR, 0.91; 95% CI, 0.49-1.67;P=.76).However, the incidence of reoperations was lower in the virtual planning group (0.76 incidents per 30 persondays) than in the conventional planning group (0.97 incidents per 30 person-days; IRR, 0.41; 95% CI, 0.22-0.76;P=.01)(Table3).therate was 0.78 incidents per 30 person-days in the virtual planning group vs 0.96 incidents per 30 person-days in the conventional planning group (IRR, 0.39; 95% CI, 0.16-0.97;P = .04).Among patients who did not receive early surgery, the rate for outpatient visits was 1.48 incidents per 30 person-days in the virtual planning group vs 1.43 incidents per 30 person-days in the conventional

Table 1 .
Baseline Demographic Characteristics of Patients Before and After Propensity Score Matching Based on Type of Preoperative Planning (continued) a ASA Physical Status Classification System status range, ASA 1 to ASA 6 (with ASA 1 indicating a healthy patient with no disease, ASA 2 indicating a patient with mild systemic disease, ASA 3 indicating a patient with severe systemic disease, ASA 4 indicating a patient with severe systemic disease that is life-threatening, ASA 5 indicating a patient who is not expected to survive without surgery, and ASA 6 indicating a patient in whom brain death has occurred).Higher ASA status indicates greater risk during anesthesia.
Association of Virtual Preoperative Planning With Postoperative Mortality and Complications medical specialty and the location of postoperative care.Furthermore, the patient's completion or noncompletion of postoperative rehabilitation, including timely mobilization, early rehabilitation, and postacute care, was likely associated with these outcomes.Therefore, the rates of outpatient visits, hospital readmissions, and functional outcomes were the balanced results of preoperative planning and the factors discussed in this paragraph.
JAMA Network Open.2020;3(8):e205830.doi:10.1001/jamanetworkopen.2020.5830(Reprinted) August 10, 2020 11/14 Downloaded From: https://jamanetwork.com/ on 09/24/2023 Baseline Demographic Characteristics in Patients With Early Surgery Before and After Propensity Score Matching According to Type of Preoperative Planning eTable 2. Baseline Demographic Characteristics in Patients Without Early Surgery Before and After Propensity Score Matching According to Type of Preoperative Planning eTable 3. Subgroup Analysis for Death in Propensity Score-Matched Patients With Early Surgery eTable 4. Subgroup Analysis for Complications in Propensity Score-Matched Patients With Early Surgery eTable 5. Subgroup Analysis for Death in Propensity Score-Matched Patients Without Early Surgery eTable 6. Subgroup Analysis for Complications in Propensity Score-Matched Patients Without Early Surgery eTable 7. Postoperative Clinical Outcomes in 1-Year Follow-Up of Unmatched Patients eTable 8. Postoperative Clinical Outcomes in 1-Year Follow-Up of All Unmatched Patients eTable 9. Baseline Characteristics of 277 Consecutive Patients Treated by Junior Resident With Use of Computer-Assisted Preoperative Planning eTable 10.Baseline Characteristics of 281 Consecutive Patients Treated by Junior Resident With Use of Conventional Preoperative Planning eFigure 1. Risk of All-Cause 90-Day Mortality in Propensity Score-Matched Patients eFigure 2. Cumulative Incidence of All-Cause 90-Day Complications in Propensity Score-Matched Patients eFigure 3. Learning Curves of Closed Reduction of Fracture Time With Use of Computer-Assisted and Conventional Preoperative Planning eFigure 4. Learning Curves of Number of Fluoroscopies With Use of Computer-Assisted and Conventional Preoperative Planning eFigure 5. Learning Curves of Estimated Blood Loss With Use of Computer-Assisted and Conventional Preoperative Planning