Periprosthetic distal femur fractures around total knee replacements: A comprehensive review

AI classification of knee prostheses from plain radiographs and real-world applications

PURPOSE

Total knee arthroplasty (TKA) is considered the gold standard treatment for end-stage knee osteoarthritis. Common complications associated with TKA include implant loosening and periprosthetic fractures, which often require revision surgery or fixation. Challenges arise when medical records related to the knee prosthesis are lost, making it difficult to plan for revision surgery effectively. This study aims to develop an artificial intelligence (AI) system to classify the types of knee prosthetic implants using plain radiographs.

METHODS

This retrospective experimental study includes seven types of knee prostheses commonly used in our hospital. The artificial intelligence (AI) system was trained using YOLO (You Only Look Once) version 9, utilizing a dataset of 3228 post-operative and follow-up knee arthroplasty X-ray images. The plain radiographic images were augmented, resulting in a dataset of 25,800 images. Model parameters were fine-tuned to optimize performance for implant classification.

RESULTS

The mean age of the patients was 62.8 years. Right knee arthroplasty was performed in 48.3% of cases, while left knee arthroplasty was performed in 51.7%. The images of knee prostheses comprised 50.9% of the dataset from the anteroposterior (AP) view and 49.1% from the lateral view. The AI model demonstrated exceptional performance metrics, achieving precision, recall, and accuracy rates of 100%, with an F1 score of 1. Additionally, the area under the curve (AUC) of the receiver operating characteristic (ROC) curve was calculated to be 100%.

CONCLUSION

This AI model successfully classifies knee prosthetic implants from plain radiographs. This capability serves as a valuable tool for surgeons, enabling precise planning for revision surgeries and periprosthetic fracture fixation surgery, ultimately contributing to improved patient outcomes. The high accuracy achieved by the AI underscores its potential to enhance surgical efficiency and effectiveness in managing knee arthroplasty complications.

Time to surgery and other risk factors for mortality and complication rates in patients with periprosthetic femoral fractures at the knee

BACKGROUND

There is a high level of evidence that a short time to surgery (TTS) improves the outcome for patients with hip fractures. Accordingly, recommendations for timely treatment have been included in national guidelines. As patient characteristics appear to be similar, it seems reasonable that these guidelines are applicable to other fracture entities, such as knee periprosthetic femoral fracture (PPF). This monocentric retrospective study aimed to investigate outcome-related risk factors, particularly TTS, for knee PPF.

METHODS

In total, 141 consecutive patients with knee PPF in a maximum-care arthroplasty and trauma centre, treated between 2006 and 2020, were retrospectively evaluated. Primary outcome variables were operative and general complications as well as mortalities within 1 year. Outcome-related risk factors were identified based on regression analysis using SPSS. For analysis of TTS, the cases were divided into two groups using a TTS of 24 h as the cutoff value.

RESULTS

The 1-year mortality was 8.3 %. Associated risk factors were age (HR 1.2; p = 0.010) and Charlson score (HR 2.1; p = 0.001). Both, surgical and general complications occurred in 20.6 % of the cases. Age (OR 1.07, p = 0.025) and a TTS > 24 h (OR 3.06, p = 0.020) were identified as risk factors for general complications. The TTS ≤ 24 h (n = 75) and TTS > 24 h (n = 66) groups were comparable in terms of baseline characteristics. Revision arthroplasty was performed more frequently in the TTS > 24 h group (p < 0.001).

CONCLUSION

1-year mortality after knee PPF was 8.3 %. With a high complication rate in the treatment of knee PPF, TTS was identified as a risk factor for general complications. Early treatment appears to be beneficial for patients with knee PPF.

A case of recurrent proximal femoral fracture after open reduction and internal fixation with bilateral locking plates for a Rorabeck type II periprosthetic fracture

INTRODUCTION AND IMPORTANCE

Periprosthetic distal femur fractures (PDFFs) are rare complications that may occur during or after total knee arthroplasty (TKA). The incidence of PDFFs is increasing. Plate internal fixation has demonstrated positive results. However, there is limited research available on the recurrence of periimplant fractures following open reduction and internal fixation with bilateral locking plates.

CASE PRESENTATION

A 70-year-old female patient was diagnosed with a Rorabeck type II fracture. Based on the patient's physical condition and available surgical options, minimally invasive open reduction, bilateral plate fixation, and allograft artificial bone grafting were chosen. The postoperative recovery was successful. However, the patient experienced a fall 2 months after the surgery, resulting in a proximal femoral fracture. After considering the patient's condition and family preferences, conservative treatment was ultimately decided upon.

CLINICAL DISCUSSION

Minimally invasive bilateral Locking Compression Plate (LCP) as a surgical approach can effectively reduce surgical risks prior to the procedure. Careful selection of screws and the use of C-arm fluoroscopy during plate contouring and fixation are essential to prevent screw penetration through the contralateral cortex. Treatment outcomes were not impacted in patients with normal bone mass; however, in this particular case, the patient had severe osteoporosis, significantly increasing the risk of refracture. It is crucial to improve postoperative monitoring and raise awareness about safety among patients and their families.

CONCLUSION

The management of periprosthetic distal femur fractures (PDFFs) is influenced by the type of fracture and bone quality. Mechanical stability and stress dispersion of internal fixation are key factors to consider. In the perioperative setting, involving experienced clinicians is essential to reduce the risk of secondary injuries that may impact treatment outcomes, especially when choosing screws for fixation in patients with low bone density.

Patient-Reported Outcomes and Range of Motion Following Knee Arthroplasty Using a Megaprosthesis in Non-Oncological Patients: A Systematic Review

BACKGROUND

This review aimed to determine outcomes following megaprostheses in non-oncological indications for knee arthroplasty, including range of motion (ROM) and patient-reported outcome measures of function, pain, and quality of life (QoL).

METHODS

A search of MEDLINE, Embase, and Cochrane via Ovid and PubMed between January 2003 and June 2023 was conducted. Studies reporting function, pain, ROM, and/or QoL in non-oncological patients who have received knee megaprostheses were included. Studies with sample sizes (n ≤ 5) were excluded. The risk of bias was assessed using the Downs and Black Quality Checklist for Health Care Intervention Studies. Central tendency measures (mean or median) were reported at each time point, and dispersion measures were extracted and reported whenever data were available.

RESULTS

A total of 30 studies (involving 1,294 megaprostheses) were included. Of which, 14 of 30 studies reviewed patients who had mixed indications; 14 of 30 looked at fracture only; 1 of 30 focused on distal femur nonunion; and 1 of 30 focused on patients who had periprosthetic infections. The average patient follow-up time was 40.1 months (range, 1.0 to 93.5). Most studies presented a high risk of bias (27 of 30), while a few (3 of 30) presented a low risk of bias. Improvements from preoperative baseline were observed in 85.7% of studies that reported baseline and follow-up data for function (12 of 14), 100.0% pain (4 of 4), 90.9% ROM (10 of 11), and 66.6% QoL (2 of 3).

CONCLUSIONS

Favorable function, pain, ROM, and QoL outcomes following knee megaprostheses in non-oncological patients were observed. Heterogeneity in outcome measures and follow-up periods prevented the pooling of data. Future comparative studies are warranted to enhance the body of evidence relating to knee megaprostheses in non-oncological patients.

Periprosthetic fracture around total knee arthroplasty: What are the advantages of minimal-invasive surgery?

OBJECTIVES

Periprosthetic femur fractures after total knee arthroplasty in older adults are mostly treated by internal fixation. Members of the GETRAUM (French Orthopedic Trauma Society) sought to compare two surgical techniques - conventional open surgery and minimally invasive surgery - with the aim of analyzing the patients' functional recovery. We hypothesized that a minimally invasive technique would produce better early functional outcomes with recovery of independence.

MATERIALS AND METHODS

This retrospective multicenter study of patients treated between 2009 and 2015 consisted of 90 fractures with a follow-up of 1 year. Demographic, preoperative data and the characteristics of fractures, type of fixation and the surgeon's experience level were collected. The endpoints were the Parker Mobility score, Katz ADL, place of residence at the time of fracture and at 6 months and one-year follow-up. All complications and one-year mortality during the follow up were searched.

RESULTS

At 6 months follow-up, the minimally invasive technique contributed to significantly better functional recovery as measured by the Parker (p < 0.05) and Katz scores (p < 0.05). However, there were no differences in these scores at one-year follow-up. The complication rate was 31% at one year follow-up. Mortality rate was 12 % (11 patients).

CONCLUSION

Our hypothesis was confirmed, as there was a difference between techniques that impacted functional recovery and independence, but only in the early postoperative phase. A minimally invasive technique appears to be beneficial in the short term for distal femur fractures after total knee arthroplasty but must be evaluated in a comparative and prospective study to fully confirm its reliability.

Revision surgery for periprosthetic fracture of distal femur after endoprosthetic replacement of knee joint following resection of osteosarcoma

Purpose

Periprosthetic fracture (PPF) is one of the severe complications in patients with osteosarcoma and carries the risk of limb loss. This study describes the characteristics, treatment strategies, and outcomes of this complication.

Methods

Patients were consecutively included who were treated at our institution between 2016 and 2020 with a PPF of distal femur. The treatment strategies included two types: 1) open reduction and internal fixation with plates and screws and 2) replacement with long-stem endoprosthesis and reinforcement with wire rope if necessary.

Results

A total of 11 patients (mean age 12.2 years (9-14)) were included, and the mean follow-up period was 36.5 (21-54) months. Most fractures were caused by direct or indirect trauma (n = 8), and others (n = 3) underwent PPF without obvious cause. The first type of treatment was performed on four patients, and the second type was performed on seven patients. The mean Musculoskeletal Tumor Society (MSTS) score was 20 (17-23). All patients recovered from the complication, and limb preservation could be achieved.

Conclusion

PPF is a big challenge for musculoskeletal oncologists, particularly in younger patients. Additionally, PPF poses a challenge for orthopedic surgeons, as limb preservation should be an important goal. Hence, internal fixation with plates and endoprosthetic replacement are optional treatment strategies based on fracture type and patient needs.

Periprosthetic Distal Femoral Fractures Around a Total Knee Arthroplasty: a Meta-analysis Comparing Locking compression Plating and Retrograde Intramedullary Nailing

Purpose

The number of total knee replacements (TKRs) performed per year has been increasing annually and it is estimated that by 2030 demand would reach 3.48 million procedures per year in the United States Of America. The prevalence of periprosthetic fractures (PPFs) around TKRs has followed this trend with incidences ranging from 0.3% to 3.5%. Distal femoral PPFs are associated with significant morbidity and mortality. When there is sufficient bone stock in the distal femur and a fracture pattern conducive to fixation, locking compression plating (LCP) and retrograde intramedullary nailing (RIMN) are commonly used fixation strategies. Conversely, in situations with loosening and deficient bone stock, a salvage procedure such as a distal femoral replacement is recognized as an alternative. This meta-analysis investigates the rates of non-union, re-operation, infection, and mortality for LCPs and RIMNs when performed for distal femoral PPFs fractures around TKRs.

Method

A search was conducted to identify articles relevant to the management of distal femoral PPFs around TKRs in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Articles meeting the inclusion criteria were then assessed for methodological quality using the methodological items for non-randomised studies (MINORS) criteria. Articles were reviewed, and data were compiled into tables for analysis.

Results

10 articles met the inclusion criteria, reporting on 528 PPFs. The overall incidence of complications was: non-union 9.4%, re-operation 12.9%, infection 2.4%, and mortality 5.5%. This meta-analysis found no significant differences between RIMN and LCP in rates of non-union (9.2% vs 9.6%) re-operation (15.1% vs 11.3%), infection (2.1% vs 2.6%), and mortality (6.0% vs 5.2%), respectively.

Conclusion

This meta-analysis demonstrated no significant difference in rates of non-union, re-operation, infection, and mortality between RIMN and LCP and both remain valid surgical treatment options.

A Novel Comprehensive Classification for Non-Prosthetic Peri-Implant Fractures

Non-prosthetic peri-implant fractures (NPPIFs) are often reported mixed with periprosthetic fractures (PPFs), but they are different entities. Due to the increase in the age of the world’s population and to the intensification of surgeries for fractures, nowadays, peri-implant fractures are a very frequent entity in clinical practice, with an increasing trend expected in the future. A clear exclusive classification of NPPIFs is not reported in the literature. The aim of this study is to provide a valid comprehensive classification for all the NPPIFs. X-rays of all the peri-implant cases treated in our unit in a 3-year period were retrospectively collected. Five orthopedic surgeons reviewed 30 X-rays of NPPIFs, providing a code according to the classification proposed. After a 3-month interval, they reviewed the same X-rays. Eighteen femoral, eight humeral, and four forearm peri-implant fractures were collected and showed to the raters. Inter- and intra-observer reliability was calculated using a k-statistic, showing a moderate agreement between observers (κ = 0.73) and a substantial agreement between the observations of the same viewer (κ = 0.82). The literature lacks a comprehensive classification for peri-implant fractures that considers all the bones and all the types of implants. The proposed classification is meant to be an instrument for orthopedic surgeons to categorize these types of fractures and seems to be simple, easy to comprehend, and reproducible. This new classification can provide the orthopedic surgeon a reliable method to clearly catalogue different fractures according to the site and the implants; the physicians can use it, through a code, in clinical practice to describe an NPPIF without the need of images. Further studies may be necessary to confirm the validity and eventually to improve the suggested classification.