The management of displaced femoral neck fractures: a narrative review

Microvasculature and trabecular bone in beagle proximal femur: Microstructural insights

BACKGROUND

Avascular necrosis of femoral head and malunion are frequent post-operative complications of femoral neck fractures. To optimize surgical techniques, this study aims to provide a microstructural understanding of intraosseous microvasculature and the trabecular bone of the femoral head and neck.

STUDY DESIGN

This anatomical study analyzed twenty-eight femora from fourteen cadaveric beagles. Common iliac arteries were infused with colored silicone-resin for vascular visualization, followed by non-decalcified hard tissue processing using the EXAKT®, and Masson's trichrome staining. Morphology and histomorphometric analysis were performed by Nikon NIS Elements BR and ImageJ-fiji.

RESULTS

Histomorphometry revealed thin, elongated trabeculae with high vascularity aligned parallel in the neck; numerous intraosseous anastomoses at the neck-shaft and head-neck junctions; thick trabeculae with smaller marrow cavities, and dense branching vascular networks near the cortex in the head. Quantitative analysis showed an inverse correlation between trabecular density and mean vascular density/vascular length density, with no significant sex or side differences. Dense connective tissue fibers maintained the microvasculature and trabeculae structure.

CONCLUSION

The femoral neck displayed an outside-in microvascular pattern via retinacular branches. Conversely, the femoral head had an inside-out pattern through epiphyseal branches reinforced by medullary branches. Dense intraosseous microvasculature aligned sub-cortically. The study identified a potential anatomical safe zone for screwing in femoral neck fractures in beagles. These findings provide an anatomical basis for translational research in joint preservation techniques for humans.

Peri-implant femoral fractures in elderly: Morbidity, mortality, treatment options and good practices

PURPOSE

Femur fractures are among the most common fractures treated surgically, representing a significant challenge for the orthopedic surgeon. Peri-implant femoral fractures (PIFFs) represent a rare complication of the surgical treatment. It is necessary to pay attention during osteosynthesis, evaluating not only the fracture site but the entire femoral skeletal structure, the characteristics of the fracture, the health comorbidities, and the risk of malunion and pseudarthrosis. There are few studies on the incidence, treatment, and outcomes of PIFFs near osteosynthesis. This study aimed to investigate PIFF after osteosynthesis of femoral fractures and evaluate the mortality after surgery and the morbidity associated with these types of fractures.

METHODS

A retrospective cohort study was carried out at the IRCCS Galeazzi Orthopedic Institute, Milan, Italy, between January, 2017 and December, 2022. Inclusion criteria were the presence of a femur fracture around an intramedullary nail to treat a previous fracture, follow-up ≥ 12 months, and patient age ≥ 65 years. Exclusion criterion was intraoperative periprosthetic fractures. The data were expressed as frequency and percentage. Continuous variables were expressed as mean ± standard deviation or median and range.

RESULTS

Overall, 25 patients were enrolled (88.0% female) and the mean age was 84.5 years (range of 70 - 92 years). There were 20 patients having type B PIFF and 5 having type C. In 22 patients, multiple comorbidities were found with an average Charlson comorbidity score of 5.5 and the mean time to peri-implant fracture was 38 months. After surgery, 1 patient (4.0%) presented renal failure, 1 (4.0%) needed removal surgery for their loosening, and 2 (8.0%) presented surgical site infection. Nine patients (36.0%) died within 1 year with a mortality rate of 20. 0% at 30 days, 8.0% at 3 months, and 8.0% at 12 months.

CONCLUSIONS

PIFFs in elderly patients are associated with high short-term mortality and morbidity, so careful planning for primary fracture surgery and patient awareness to ensure prolonged compliance and a healthy lifestyle are essential for prevention.

Management of Hip Fractures

Hip fractures in women are a serious health concern, demanding prompt treatment and pain control methods. This study examines fracture frequency, diagnostic techniques, and classification, focusing on femoral neck and intertrochanteric fractures. It discusses risk factors including age, gender, bone strength, and medication and their impact on fracture risk. Treatments range from noninvasive care to surgeries such as internal fixation and joint replacement. Perioperative measures such as anesthesia, antibiotics, and clot prevention to improve outcomes and lessen complications are also discussed. Postsurgery care emphasizes pain relief strategies, including opioids, nerve blocks, and modern methods such as real-time messaging for pain control.

Traumaplasty: When and How to Perform Acute Arthroplasty for Fractures Around the Hip in the Elderly Patient

Acute fractures around the hip are prevalent injuries associated with potentially devastating outcomes. The growing utilization of arthroplasty for femoral neck fractures in the elderly is likely a result of improvements in reoperation rates and postoperative function. Compared to hemiarthroplasty, total hip arthroplasty is associated with a slight functional benefit that is unlikely noticeable for many patients, as well as minimal differences in complications and patient reported outcome measures. However, the evidence supporting cement use in femoral stem fixation is robust. Multiple high power randomized controlled trial-based studies indicate cement fixation brings more predictable outcomes and fewer reoperations. In the setting of acute acetabular fracture, total hip arthroplasty is a favorable approach for elderly patients and fracture patterns associated with increased risk of revision after open reduction and internal fixation. Variations in patient characteristics and fracture patterns demand careful consideration whenever selecting the optimal treatment. In fracture patient populations, comanagement is an important consideration when seeking to reduce complications and promote cost-effective quality care.

The impact of electronic pathways and digital systems on neck of femur fracture outcomes globally: a systematic review

INTRODUCTION

Electronic pathways (e-pathways) and digital systems are novel interventions with several uses in healthcare, ranging from clinical decision support systems to checklists for care delivery. Their application in the management of neck of femur (NOF) fractures is evolving and they may play a key role in facilitating improvements in care delivery. The primary aim of this review was to outline the impact of e-pathways/digital systems on NOF fracture outcomes.

METHODS

A systematic literature search was performed using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. A total of 698 citations were evaluated, of which 38 passed the inclusion/exclusion criteria. Six studies were then finalised following full-text review. Heterogenous data meant a narrative synthesis was undertaken. Risk of bias for each paper was assessed using the Downs and Black scale.

RESULTS

A statistically significant improvement was demonstrated for time to theatre (3/6 studies), length of hospital stay (2/6 studies) and secondary fracture prevention (2/6 studies). Although postoperative delirium and mortality improved with the introduction of e-pathways/digital systems, statistical significance was not achieved. No outcome measures were adversely affected.

CONCLUSIONS

This systematic review of the literature demonstrates that e-pathways and digital systems are promising novel interventions, displaying a significant positive impact on several NOF fracture outcomes. Owing to the novel nature of e-pathways and digital systems in orthopaedics, a limited number of studies were identified for review, each with variable study design. More high quality homogenous prospective cohort studies with a standardised primary outcome measure are required for more definitive conclusions of efficacy to be drawn.

Risk Factors of the 2-Year Mortality after Bipolar Hemiarthroplasty for Displaced Femoral Neck Fracture

Purpose

This study investigates the relationship between preoperative neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-C-reactive protein ratio (LCR), albumin, and 2-year mortality in elderly patients having hemiarthroplasty for displaced femoral neck fracture (FNF).

Materials and Methods

We retrospectively reviewed 284 elderly patients who underwent hemiarthroplasty for Garden type IV FNF from September 2014 to September 2020. Using the receiver operating characteristic curve, optimal cutoff values for LCR, NLR, and albumin were established, and patients were categorized as low or high. Associations with 2-year mortality were evaluated through univariate and multivariate Cox regression analyses.

Results

Of the 284 patients, 124 patients (45.9%) died within 2 years post-surgery. The optimal cutoff values were: LCR at 7.758 (specificity 58.5%, sensitivity 25.0%), NLR at 3.854 (specificity 39.2%, sensitivity 40.0%), and albumin at 3.750 (specificity 65.9%, sensitivity 21.9%). Patients with low LCR (<7.758), high NLR (≥3.854), and low albumin (<3.750) had a statistically significant reduced survival time compared to their counterparts.

Conclusion

Lower preoperative LCR and albumin levels, along with higher NLR, effectively predict 2-year mortality and 30-day post-surgery complications in elderly patients with Garden type IV FNF undergoing hemiarthroplasty.

Total hip arthroplasty for failed internal fixation of femoral neck fracture: a retrospective study with 2-14 years' follow-up of 345 patients

OBJECTIVES

The purpose of this study was to analyze mid- to long-term outcomes of total hip arthroplasty (THA) following failed internal fixation of femoral neck fracture.

METHODS

This study retrospectively analyzed 345 patients with femoral neck fracture who underwent THA after failure of internal fixation at our hospital between January, 2003 and December, 2019. Patients older than 55 years (n = 175) and patients no older than 55 years (n = 170) were compared in terms of complications and survival rates during follow-up, which lasted a mean of 6 years.

RESULTS

The two age groups showed similarly low incidence of complications and similarly long periods of survival without revision surgery. Only three younger patients and two older patients underwent revision surgery during follow-up. The two groups showed similarly high survival rates at the end of follow-up (> 93%). Younger patients showed significantly bettter Harris hip score at last follow-up (90.2 vs. 88.1 points, p < 0.001) without clinically significant difference, but they required THA significantly earlier after internal fixation (4.4 vs. 6.8 years, p < 0.001).

CONCLUSIONS

THA after failed internal fixation of femoral neck fracture is a well tolerated and effective procedure in older and younger patients.

A comparison of internal fixation and hemiarthroplasty in the management of un- or minimally displaced hip fractures in patients over 60 years old

BACKGROUND

The incidence of hip fractures in the elderly is increasing. Minimally displaced and undisplaced hip fractures can be treated with either internal fixation or hemiarthroplasty.

OBJECTIVES

To identify the revision rate of internal fixation and hemiarthroplasty in patients 60 years or older with Garden I or II hip fractures and to identify risk factors associated with each method.

METHOD

A retrospective analysis was conducted from 2 Major Trauma Centres and 9 Trauma Units between 01/01/2015 and 31/12/2020. Patients managed conservatively, treated with a total hip replacement and missing data were excluded from the study.

RESULTS

1273 patients were included of which 26.2% (n = 334) had cannulated hip fixation (CHF), 19.4% (n = 247) had a dynamic hip screw (DHS) and 54.7% (n = 692) had a hemiarthroplasty. 66 patients in total (5.2%) required revision surgery. The revision rates for CHF, DHS and hemiarthroplasty were 14.4%, 4%, 1.2% (p<0.001) respectively. Failed fixation was the most common reason for revision with the incidence increasing by 7-fold in the CHF group [45.8% (n = 23) vs. 33.3% (n = 3) in DHS; p<0.01]. The risk factors identified for CHF revision were age >80 (p<0.05), female gender (p<0.05) and smoking (p<0.05). The average length of hospital stay was decreased when using CHF compared to DHS and hemiarthroplasty (12.6 days vs 14.9 days vs 18.1 days respectively, p<0.001) and the 1 year mortality rate for CHF, DHS and hemiarthroplasty was 2.5%, 2% and 9% respectively.

CONCLUSIONS

Fixation methods for Garden I and II hip fractures in elderly patients are associated with a higher revision rate than hemiarthroplasty. CHF has the highest revision rate at 14.4% followed by DHS and hemiarthroplasty. Female patients, patients over the age of 80 and patients with poor bone quality are considered high risk for fixation failure with CHF. Hemiarthroplasty is a suitable alternative with lowest revision rates. When considering an internal fixation method, DHS is more robust than a screw construct.

[Femoral neck fractures]

Femoral neck fractures (FNF) are the most frequent fractures in the older population and are also of high socioeconomic importance due to the high risk of mortality. The diagnostics are based on the clinical examination and imaging procedures. The classification systems used in the routine clinical practice are oriented towards the prognosis and are therefore a valuable aid in making decisions for the selection of the treatment procedure. Early surgery is decisive for the success of treatment. Older patients (> 60 years) with arthritically damaged hips and a high degree of fracture dislocation benefit from prompt hip replacement (bipolar systems, total hip arthroplasty, dual mobility systems). In contrast, joint-preserving surgery by osteosynthesis is indicated in younger patients with a low degree of dislocation. This article summarizes the clinically relevant aspects of FNF and gives an overview of current treatment strategies with inclusion of the scientific literature.

Gamma Nail Combined with One Cannulated Compression Screw Fixation for Treating Pauwels Type III Femoral Neck Fractures in Young and Middle-Aged Adults: Clinical Follow-Up and Biomechanical Studies

OBJECTIVE

Recently, some clinical studies have reported the use of an intramedullary nailing system for treating unstable femoral neck fractures or femoral neck fractures combined with femoral shaft fractures in young adults, and the results have indicated certain advantages. However, no study has investigated the mechanical properties of this method. We aimed to evaluate the mechanical stability and clinical efficacy of the Gamma nail combined with one cannulated compression screw (CCS) fixation for treating Pauwels type III femoral neck fracture in young and middle-aged adults.

METHODS

This study consists of two parts: a clinical retrospective study and randomized controlled biomechanical test. Twelve adult cadaver femora were used to test and compare the biomechanical properties among three fixation methods: three parallel CCS (group A), Gamma nail (group B), and Gamma nail combined with one cannulated compression screw (group C). The single continuous compression test, cyclic load test, and ultimate vertical load test were used to evaluate the biomechanical performance of the three fixation methods. We also conducted a retrospective study of 31 patients with Pauwels type III femoral neck fractures, including 16 patients with fractures fixed with three parallel CCS (CCS group) and 15 patients with fractures fixed with Gamma nail combined with one CCS (Gamma nail + CCS group). The patients were followed up for at least 3 years, and all were evaluated for surgical time (from skin incision to closure), surgical blood loss, hospital stay, and the Harris hip score.

RESULTS

In mechanical experiments, we have found that the mechanical advantages of Gamma nail fixation are not as good as those of conventional CCS fixation. However, the mechanical properties of Gamma nail fixation combined with one cannulated screw perpendicular to the fracture line are much better than those of Gamma nail fixation and CCS fixation. No significant difference was found in the incidence of femoral head necrosis and nonunion between the CCS and Gamma nail + CCS groups. Moreover, there was no statistically significant difference in the Harris hip scores between the two groups. One patient in the CCS group showed significant withdrawal of cannulated screws at 5 months after surgery, whereas in the Gamma nail + CCS group, all patients, including those with femoral neck necrosis, showed no loss of stability of the fixation.

CONCLUSION

Among the two fixation methods evaluated in this study, Gamma nail combined with one CCS fixation showed better biomechanical properties and may reduce complications associated with unstable fixation devices.

Proportion of stable femoral neck fracture types in different age groups: a population-based study

OBJECTIVE

The treatment and incidence of femoral neck fracture (FNF) in older patients is controversial. We investigated the new AO (Arbeitsgemeinschaft für Osteosynthese) classification in patients with FNF by age to determine the proportions of stable fracture and change trends according to patients' age.

METHODS

We divided patients with FNF hospitalized in Xi'an Honghui Hospital from 2018 to 2020 into five groups according to age: young (<50 years), middle-aged (50-59 years), young-elderly (60-69 years), middle-elderly (70-79 years), and very elderly (≥80 years) groups. We retrospectively collected data of patients' sex, admission date, fracture side, mechanism of injury, and new AO classification.

RESULTS

In total, 2071 patients were included for analysis, with 1329 women (64.2%); 1106 patients (53.4%) had left-side fracture. The main mechanism of injury was falling. In the young-elderly, middle-elderly, and very-elderly groups, 33.3%, 29.2%, and 24.1% had stable fracture type, respectively). The proportion of patients with FNF did not show a change trend by age during the 3-year investigation period.

CONCLUSION

In our study, the proportion of older patients with FNF did not increase, and as many as a third of patients with FNF aged 50 to 70 years had stable fracture.

Low lymphocyte-to-C-reactive protein ratio relates to high 1-year mortality in elderly patients undergoing hemiarthroplasty for displaced femoral neck facture

OBJECTIVE

Lymphocyte-to-C-reactive protein (CRP) ratio (LCR) is a novel biomarker for predicting poor prognosis in many diseases. This study aims to analyze the association between preoperative LCR and 1-year mortality in elderly patients with displaced FNF undergoing hemiarthroplasty.

METHODS

Between May 2017 and May 2019, a retrospective study including 364 elderly patients undergoing hemiarthroplasty for displaced FNF was performed. LCR was defined as the ratio of preoperative lymphocyte count to CRP level. The optimal cutoff value of LCR was determined by receiver operating characteristic curve, and all patients were categorized into low-LCR group and high-LCR group accordingly. The relationship between LCR and 1-year mortality was evaluated by using univariate and multivariate Cox regression analysis. Furthermore, the complications within 30 days after surgery, length of hospital stay, and perioperative red blood cell transfusion were also analyzed stratified by LCR.

RESULTS

A total of 47 patients (12.9%) died within 1-year follow-up after surgery. The optimal cutoff value for LCR was 30,560 (specificity 76.6% and sensitivity 63.4%). Low-LCR (≤ 30,560) group had a higher mortality rate than high-LCR group (23.53% vs. 5.21%, P < 0.001). In multivariate analysis, low LCR, hypoalbuminemia, and Age-Adjusted Charlson Comorbidity Index ≥ 6 were identified as independent predictors for 1-year mortality. Moreover, low level of LCR was associated with high rate of total complications (19.6% vs. 11.4%, P = 0.029), perioperative transfusions (37.9% vs. 27.0%, P = 0.027), and longer hospital stay (7.84 ± 2.40 vs. 7.30 ± 2.32, P = 0.031).

CONCLUSIONS

The low level of preoperative LCR can effectively predict 1-year mortality and 30-day total complications after surgery in elderly patients with displaced FNF undergoing hemiarthroplasty.

[Research progress in biomechanics of common internal fixation for femoral neck fracture]

OBJECTIVE

To summarize the characteristics and biomechanical research progress of common internal fixation for femoral neck fractures in recent years, so as to provide reference to clinical treatment of femoral neck fracture.

METHODS

The domestic and foreign relevant literature on biomechanics of internal fixation of femoral neck fracture in recent years was reviewed, and the biomechanical research progress was summarized.

RESULTS

Among the internal fixations currently used in the treatment of femoral neck fractures, three cannulated screws can provide sliding compression at the end of the fracture, but the shear resistance is weak, and the risk of long-term internal fixation failure is high; dynamic hip screw and proximal femoral locking plate have excellent angle stability and overall strength; medial buttress plate can transform vertical shear force into compressive stress to promote fracture healing and produce a certain anti-rotation effect; femoral neck system can support the fracture in multi-axial direction, with excellent anti-rotation and anti-shortening properties; and cephalomedullary nails have high overall strength and failure load. Different internal fixations have their own indications due to differences in structure and biomechanics.

CONCLUSION

At present, there is no detailed standard guidance of internal fixation selection. Clinically, the appropriate treatment should be selected according to the fracture types of patients.

Hip fractures re-operation compared with death at two year in elderly patients: lowest risk of revision with dual mobility total hip arthroplasty than with bipolar hemiarthroplasty or internal fixation of Garden I and II

PURPOSE

This study determined at two year follow-up the lifetime risk of re-operation for elderly patients with hip fractures undergoing internal fixation, dual mobility total hip arthroplasty, or bipolar hemiarthroplasty, using death of the patient as a competing risk.

MATERIALS AND METHODS

With the hypothesis that arthroplasties may have less complications without increasing mortality even for Garden I and Garden II fractures, we retrospectively reviewed 317 hips with femoral neck fractures operated between January 2015 and August 2019. The mean age at time of surgical intervention was 82.4 years (range 65 to 105). Sixty patients presented a nondisplaced hip fracture (Garden I or II) treated by internal fixtion (I-F), and 257 were treated by hip arthroplasty: 118 dual mobility total hip arthroplasty (DM-THA) and 139 with a bipolar hemiarthroplaty (B-H). Demographics, surgical and complications data, and mortality were collected and compared for each group.

RESULTS

The overall mortality rate was 22.4% at two years, and similar (p = 0.98) in all groups, respectively 22%, 22%, and 23% for DM-THA, B-H, and I-F groups. With dual mobility THA, the cumulative incidence of re-operations for any reason was (lower (9%) than with internal fixation (22%) or bipolar hemiarthroplasties (19%).

CONCLUSION

Using a double mobility total prosthesis does not increase the post-operative mortality of the patients, nor does it increase their survival. But, reducing the risk of complications certainly improves their quality of life during the little time they have left .

Comparison of the Effect of Rhombic and Inverted Triangle Configurations of Cannulated Screws on Internal Fixation of Nondisplaced Femoral Neck Fractures in Elderly Patients

Objective

To investigate whether four‐screw fixation in rhombic configuration could improve the clinical outcomes and decrease the complication rate compared with three‐screw fixation in inverted triangle configuration in elderly patients with nondisplaced femoral neck fractures.

Method

From January 2018 to January 2019, 91 elderly patients with nondisplaced femoral neck fractures who were treated with a cannulated screw system were reviewed retrospectively. The inverted triangle configuration was applied in 51 patients and rhombic configuration in 40 patients. The demographic and perioperative information of the patients were extracted from medical records and surgical records. Variables including incision size, surgical blood loss, surgical time, fluoroscopy time, hospital stays, fracture union time, postoperative visual analogue scale (VAS) scores, and complications were compared between the two groups. Also, Harris hip score at the final follow‐up was used to evaluate the functional outcomes.

Results

All patients were followed up from 24 to 36 months, with an average of 29.75 months. The average age of patients was 72.37 ± 7.16 years. No significant differences were found between the two groups with regard to patients' age, gender, affected side, Garden classification, Pauwels classification and comminution of posterior wall (P > 0.05). We found shorter incision size (P < 0.001), less blood loss (P = 0.020), less surgical time (P = 0.026), and shorter fluoroscopy time (P < 0.001) in inverted triangle configuration group. However, shorter hospital stays (P = 0.001) and fracture union time (P = 0.002) were found in the rhombic configuration group. The VAS scores were lower in the rhombic configuration group at the first (P < 0.001) and third months (P = 0.010), but no significant difference was found at the sixth month (P = 0.075). Meanwhile, the total complication rate was relatively lower in the rhombic configuration group compared to the inverted triangle configuration group (P = 0.041). Harris hip score presented no significant difference between the two groups at final follow‐up (P = 0.078). No wound infection or cortical perforation occurred in either group.

Conclusion

Four‐screw fixation in rhombic configuration was superior to three‐screw fixation in inverted triangle configuration in the treatment of nondisplaced femoral neck fractures in elderly patients in terms of less early postsurgical pain, shorter fracture union time, and lower complication rate.

Comparison of femoral nerve block and acupuncture analgesia for acute preoperative pain in elderly patients with femoral neck fracture: a retrospective study

OBJECTIVE

This study was to compare the efficacy of femoral nerve block (FNB) and acupuncture for acute preoperative pain in patients with femoral neck fracture (FNF).

METHODS

From June 2017 to June 2019, 130 patients with FNF were included in this study. Sixty-six patients received FNB treatment (FNB group) and sixty-four patients received acupuncture treatment (Acupuncture group). The clinical information, visual analog scale (VAS) scores, nursing quality scores, sleep quality scores, delirium numbers, and perioperative complications were collected and compared between the 2 groups.

RESULTS

The resting VAS score and the exercise VAS score decreased after FNB or acupuncture in both groups. Thirty minutes after analgesia, the resting VAS scores in the FNB group and the acupuncture group were 27.3±8.0 and 27.9±7.8, respectively (P=0.67); while exercise VAS scores were 60.2±10.4 and 59.5±9.8, respectively (P=0.73). In addition, there was no statistical difference in the VAS score between the two groups on day 1 and day 2 after admission. There was no statistical difference in nursing quality, sleep rhythm disorder, sleep quality, or times of mental disorder between the two groups.

CONCLUSION

FNB analgesia and acupuncture analgesia are safe and effective for the control of acute preoperative pain in senile patients with femoral neck fracture. Both methods have good analgesic effects, which can improve nursing and sleep quality, and reduce the incidence of delirium. As a traditional Chinese medicine method, acupuncture analgesia can effectively manage the acute preoperative pain in senile femoral neck fracture patients.

A Postoperative Displacement Measurement Method for Femoral Neck Fracture Internal Fixation Implants Based on Femoral Segmentation and Multi-Resolution Frame Registration

Femoral neck fractures have a high incidence in the geriatric population and are associated with high mortality and disability rates. With the minimally invasive nature, internal fixation is widely used as a treatment option to stabilize femoral neck fractures. The fixation effectiveness and stability of the implant is an essential guide for the surgeon. However, there is no long-term reliable evaluation method to quantify the implant’s fixation effect without affecting the patient’s behavior and synthesizing long-term treatment data. For the femur’s symmetrical structure, this study used 3D convolutional networks for biomedical image segmentation (3D-UNet) to segment the injured femur as a mask, aligned computerized tomography (CT) scans of the patient at different times after surgery and quantified the displacement in the specified direction using the generated 3D point cloud. In the experimental part, we used 10 groups containing two CT images scanned at the one-year interval after surgery. By comparing manual segmentation of femur and segmentation of femur as a mask using neural network, the mask obtained by segmentation using the 3D-UNet network with symmetric structure fully meets the requirements of image registration. The data obtained from the 3D point cloud calculation is within the error tolerance, and the calculated displacement of the implant can be visualized in 3D space.