Distal femur fractures: basic science and international perspectives

Distal femur fractures are challenging injuries to manage, and complication rates remain high. This article summarizes the international and basic science perspectives regarding distal femoral fractures that were presented at the 2022 Orthopaedic Trauma Association Annual Meeting. We review a number of critical concepts that can be considered to optimize the treatment of these difficult fractures. These include biomechanical considerations for distal femur fixation constructs, emerging treatments to prevent post-traumatic arthritis, both systemic and local biologic treatments to optimize nonunion management, the relative advantages and disadvantages of plate versus nail versus dual-implant constructs, and finally important factors which determine outcomes. A robust understanding of these principles can significantly improve success rates and minimize complications in the treatment of these challenging injuries.

Outcomes of Distal Third Femur Fractures in Patients 18 Years and Older: A Pilot Study

INTRODUCTION

The selection of the most optimal fixation method for fractures of the distal femur, whether intramedullary nail (NL), lateral locking plate (PL), or nail/plate (NP) is not always clear. This study retrospectively evaluates surgical patients with distal femur fractures and introduces a pilot study using cluster analysis to identify the most optimal fracture fixation method for a given fracture type.

METHODS

This is a retrospective cohort study of patients 18 years and older with an isolated distal femur fracture who presented to our Level-1 trauma center between January 1, 2012, and December 31, 2022, and obtained NL, PL, or NP implants. Patients with polytrauma and those without at least six months of follow-up were excluded. A chart review was used to obtain demographics, fracture classification, fixation method, and postoperative complications. A cluster analysis was performed. The following factors were used to determine a successful outcome: ambulatory status pre-injury and 6-12 months postoperatively, infection, non-union, mortality, and implant failure.

RESULTS

A total of 169 patients met inclusion criteria. No statistically significant association between the fracture classification and fixation type with overall outcome was found. However, patients treated with an NP (n = 14) had a success rate of 92.9% vs only a 68.1% success rate in those treated with a PL (n = 116) (p = 0.106). The most notable findings in the cluster analysis (15 total clusters) included transverse extraarticular fractures demonstrating 100% success if treated with NP (n = 6), 50% success with NL (n=2), and 78.57% success with PL fixation (n=14). NP constructs in complete articular fractures demonstrated success in 100% of patients (n = 5), whereas 77.78% of patients treated with NL (n = 9) and 61.36% of those treated with PL (n = 44).

CONCLUSIONS

Plate fixation was the predominant fixation method used for distal third femur fractures regardless of fracture classification. However, NP constructs trended towards improved success rates, especially in complete intraarticular and transverse extraarticular fractures, suggesting the potential benefit of additional fixation with these fractures. Cluster analysis provided a heuristic way of creating patient profiles in patients with distal third femur fractures. However, a larger cohort study is needed to corroborate these findings to ultimately develop a clinical decision-making tool that also accounts for patient specific characteristics.

Bilateral Hoffa Fractures of the Medial Femoral Condyles: A Case Report and Review of the Literature

Introduction

Intra-articular distal femoral fractures in the coronal plane, widely described as Hoffa fractures, are a rare entity. Lateral femoral condyles are mostly affected, while diagnosis can be challenging. Bilateral medial femoral condyle fractures are exceedingly scarce, with only one case being published in recent literature.

Case Report

We present a case of a white 65-year-old man with bilateral medial femoral condyle Hoffa fractures caused by a crush injury. The patient was treated operatively by two different teams operating simultaneously on both sides, with good clinical and radiological outcomes after a follow-up period of 3 months.

Conclusion

A literature review was conducted to analyze the potential mechanism of injury, diagnostic methods, and therapeutic approach. Bilateral medial Hoffa fractures are rare injuries concerning the orthopedic trauma field and this is the first case described, that was treated operatively with good functional outcomes.

Single staged buttress plating with constrained knee arthroplasty for distal femur fractures in the elderly

Treatment options for distal femur fractures include open reduction internal fixation (ORIF), arthroplasty, or a hybrid of both. We present a 76 year old female with left knee pain secondary to known osteoarthritis, known lateral condyle insufficiency fracture, and an acute medial condyle fracture. In order to solve the acute and chronic problems in a single procedure, a combined ORIF and constrained condylar knee (CCK) arthroplasty was performed. Arthroplasty alone would have required a highly constrained distal femur replacement, and ORIF alone would have caused prolonged immobilization and continued morbidity from unaddressed chronic problems. We chose a CCK as a less constrained implant would not have protected our ORIF which contained the medial collateral ligament attachment. This technique avoids the complications of ORIF alone, and avoids the known complications of increased constraint in total knee arthroplasty.

Prediction of fracture nonunion leading to secondary surgery in patients with distal femur fractures

Aims

Several previously identified patient-, injury-, and treatment-related factors are associated with the development of nonunion in distal femur fractures. However, the predictive value of these factors is not well defined. We aimed to assess the predictive ability of previously identified risk factors in the development of nonunion leading to secondary surgery in distal femur fractures.

Methods

We conducted a retrospective cohort study of adult patients with traumatic distal femur fracture treated with lateral locking plate between 2009 and 2018. The patients who underwent secondary surgery due to fracture healing problem or plate failure were considered having nonunion. Background knowledge of risk factors of distal femur fracture nonunion based on previous literature was used to form an initial set of variables. A logistic regression model was used with previously identified patient- and injury-related variables (age, sex, BMI, diabetes, smoking, periprosthetic fracture, open fracture, trauma energy, fracture zone length, fracture comminution, medial side comminution) in the first analysis and with treatment-related variables (different surgeon-controlled factors, e.g. plate length, screw placement, and proximal fixation) in the second analysis to predict the nonunion leading to secondary surgery in distal femur fractures.

Results

We were able to include 299 fractures in 291 patients. Altogether, 31/299 fractures (10%) developed nonunion. In the first analysis, pseudo-R2 was 0.27 and area under the receiver operating characteristic curve (AUC) was 0.81. BMI was the most important variable in the prediction. In the second analysis, pseudo-R2 was 0.06 and AUC was 0.67. Plate length was the most important variable in the prediction.

Conclusion

The model including patient- and injury-related factors had moderate fit and predictive ability in the prediction of distal femur fracture nonunion leading to secondary surgery. BMI was the most important variable in prediction of nonunion. Surgeon-controlled factors had a minor role in prediction of nonunion.

Hip and distal femur fracture outcomes over three successive UK lockdown periods during the COVID-19 pandemic: what have we learnt? : a single-centre retrospective cohort study

Aims

This study assessed the impact of COVID-19 on hip and distal femur fracture patient outcomes across three successive UK lockdown periods over one year.

Methods

A single-centre retrospective cohort study was performed at an acute NHS Trust. Hip and distal femur fracture patients admitted within the first month from each of the three starting dates of each national lockdown were included and compared to a control group in March 2019. Data were collected as per the best practice tariff outcomes including additional outcomes as required. Data collection included COVID-19 status, time to theatre, 30-day mortality, presence of acute kidney injury (AKI) and pneumonia, and do not attempt cardiopulmonary resuscitation (DNACPR) status. Data were analyzed using an independent-samples t-test or chi-squared test with Fisher’s exact test where applicable. A p-value of < 0.05 was considered statistically significant.

Results

A total of 95 patients during the pandemic were included and 20 were COVID-positive. Patients experienced a statistically significant increase in time to theatre in Lockdown 1 compared to 2019 (p = 0.039) with a decrease with successive lockdown periods by Lockdown 3. The 30-day mortality increased from 8.8% in 2019 to 10.0% to 14.8% in all lockdown periods. COVID-positive patient mortality was 30.0% (p = 0.063, odds ratio (OR) = 4.43 vs 2019). The rates of AKI and pneumonia experienced were higher for patients during the pandemic. The highest rates were experienced in COVID-positive patients, with 45.0% of patients with AKI versus 27.0% in 2019 (p = 0.38, OR = 1.80), and 50.0% of patients diagnosed with pneumonia versus 16.2% in 2019 (p = 0.0012, OR = 5.17). The percentage of patients with a DNACPR increased from 30.0% in 2019 to 60.7% by Lockdown 3 (p = 0.034, OR = 3.61).

Conclusion

COVID-positive hip and distal femur fracture patients are at a higher risk of mortality due to AKI and pneumonia. Patient outcomes have improved with successive lockdowns to pre-pandemic levels.

Cite this article: Bone Jt Open 2021;2(12):1017–1026.

Impact on periosteal vasculature after dual plating of the distal femur: a cadaveric study

Although dual plating of distal femur fractures has been described for injuries at risk of varus displacement, the vascular insult to the medial distal femur utilizing this technique is unknown. The aim of this study was to evaluate the perfusion of the medial distal femoral periosteal arteries after supplemental medial plating of the distal femur.

Methods

Fifteen human fresh-frozen cadaveric femora were thawed and randomized to lateral locked plating alone or with supplemental medial plate fixation. Conventional submuscular medial plating was performed using a 12-hole small fragment plate and multiple cortical screws. The superficial femoral artery was injected with latex dye. Specimens were dissected. The patency of the medial distal femoral periosteal vessels was evaluated.

Results

Four vessels were consistently observed traversing the distal medial femur: the transverse and descending (d-MMPA) branches of the medial metaphyseal periosteal artery, and the transverse and longitudinal branches of the descending geniculate artery. The anterior longitudinal arch (ALA) was present in 13 of 15 specimens and was fed by the d-MMPA. The median number of periosteal arteries occluded by the medial plate was 2 (6 out of 8 specimens). The d-MMPA was occluded in 6 of 8 medially plated femurs, resulting in a complete lack of perfusion of the ALA.

Conclusions

Submuscular medial plating of the distal femur compressed the d-MMPA in the majority of specimens. This vessel gives rise to the ALA, which lacked perfusion in these specimens. This vascular insult could affect the healing of metaphyseal distal femur fractures treated with dual plating.

Sensitivity and specificity of modified RUST score using clinical and radiographic findings as a gold standard

Aims

The modified Radiological Union Scale for Tibia (mRUST) fractures score was developed in order to assess progress to union and define a numerical assessment of fracture healing of metadiaphyseal fractures. This score has been shown to be valuable in predicting radiological union; however, there is no information on the sensitivity, specificity, and accuracy of this index for various cut-off scores. The aim of this study is to evaluate sensitivity, specificity, accuracy, and cut-off points of the mRUST score for the diagnosis of metadiaphyseal fractures healing.

Methods

A cohort of 146 distal femur fractures were retrospectively identified at our institution. After excluding AO/OTA type B fractures, nonunions, follow-up less than 12 weeks, and patients aged less than 16 years, 104 sets of radiographs were included for analysis. Anteroposterior and lateral femur radiographs at six weeks, 12 weeks, 24 weeks, and final follow-up were separately scored by three surgeons using the mRUST score. The sensitivity and specificity of mean mRUST score were calculated using clinical and further radiological findings as a gold standard for ultimate fracture healing. A receiver operating characteristic curve was also performed to determine the cut-off points at each time point.

Results

The mean mRUST score of ten at 24 weeks revealed a 91.9% sensitivity, 100% specificity, and 92.6% accuracy of predicting ultimate fracture healing. A cut-off point of 13 points revealed 41.9% sensitivity, 100% specificity, and 46.9% accuracy at the same time point.

Conclusion

The mRUST score of ten points at 24 weeks can be used as a viable screening method with the highest sensitivity, specificity, and accuracy for healing of metadiaphyseal femur fractures. However, the cut-off point of 13 increases the specificity to 100%, but decreases sensitivity. Furthermore, the mRUST score should not be used at six weeks, as results show an inability to accurately predict eventual fracture healing at this time point.

Cite this article: Bone Jt Open 2021;2(10):796–805.

The Clinical and Radiological Evaluation of Far Cortex Locking Plate in Distal Femur Fractures

Introduction Locking plates in distal femur fractures were associated with a high rate of non-union and hardware failure. To overcome these drawbacks far cortex locking (FCL) concept was introduced. It is a novel bridge plating strategy to enhance interfragmentary motion for the promotion of secondary bone healing while retaining sufficient construct strength. The present study evaluated the effects of diaphyseal FCL fixation on fracture healing for periarticular locking plates used for fixation of distal femur fractures.  Materials and methods Our cohort was of 11 consecutive patients who presented to emergency after distal femur fracture and underwent surgery with the FCL plate between January 2015 and January 2016. Clinical (KOOS) and radiological evaluation of all patients was done to look for knee scores and union. Also, other complications like infection, non-union, painful hardware, implant failure were recorded  Results No non-union or hardware failure was observed in our cohort of 11 patients. Early callus formation was seen and partial weight-bearing was started at an average of 6 weeks (5-8 weeks). Average time to clinical healing was 10 weeks (8-13 weeks) whereas radiographic union was seen at 16 weeks (14-17 weeks). One patient with an open fracture had superficial surgical wound infection which healed uneventfully after one debridement and with IV antibiotics. The average knee injury and osteoarthritis outcome score (KOOS) at final follow-up was 91 (87-95) in our cohort. Conclusion FCL is an effective method to reduce construct stiffness, promote early callus formation, decrease non-union rate and achieve biological healing while retaining sufficient strength to prevent hardware failure.

Preliminary results of a staged non-biological strategy

INTRODUCTION

Infected post-traumatic distal femur defects remain a therapeutic challenge. Non-biological reconstruction offers an option for avoiding complex biological knee arthrodesis procedures. The Compress^Ⓡ implant is an alternative to the traditional distal femur stemmed megaprosthesis. The aim of this study is to analyse the first patients treated with a distal femur Compress^Ⓡ prosthesis to manage massive infected post-traumatic defects of the distal femur with joint involvement.

METHODS

We retrospectively reviewed all patients with massive infected defects of the distal femur where this implant was used in a two-stage strategy, together with an antibacterial coating hydrogel (DAC^Ⓡ). The specific protocol, microbiological data, clinical and radiological results, complications, functional results and prosthesis survivorship were determined. Follow-up was for a minimum of 12 months, or until implant removal.

RESULTS

Ten patients (11 Compress^Ⓡ implants) with a mean age of 52 years (range 35-73) were included. On average, patients had undergone 4.4 previous surgical procedures before index surgery. The mean bone defect was 14 cm (range 8-21). After a median follow-up of 27 months (range 12-50 months) no patient had presented with recurrence of the infection, and limb salvage was achieved in all cases. Two patients suffered aseptic loosening which required revision of the femoral component. The short-term survivorship of the implant in our series was 81.8% at 4 years, with all failures occurring in the first 7 months. After this 7-month time threshold, we encountered no further loosening. Regarding functional outcomes, patients had a mean knee ROM of -4/86, expressed high overall satisfaction with the procedure according to the SAPS scale, and had an average LEFS of 52.5% (40-72.5%).

CONCLUSION

Non-biological reconstruction of the distal femur with the Compress^Ⓡ implant is a valid option in selected patients with massive infected defects with joint involvement. Survivorship was high, with all loosening occurring in the first months after surgery-representing a failure in the osseointegration of the implant.

Surgical Treatment of Distal Femur Fractures in Geriatric Patients

Introduction:

The treatment of distal femur fractures in geriatric patients is challenging and has a high perioperative morbidity and mortality. Treatments have evolved significantly in the past decades. The aim of our study was to analyze local and systemic morbidity and mortality, as well as functional results in this frail cohort treated with distal femur locking plates.

Materials and methods:

In this single-institution case series, we retrospectively analyzed the data of patients aged 65 years and older with fractures of the distal femur between March 2013 and March 2018. All patients were operated with distal femur locking plates. Points of interest included perioperative morbidity, mortality, weight-bearing status, and care-dependency after hospital discharge.

Results:

We assessed 49 patients (median age: 86.5 years) with 52 distal femur fractures (AO type A 77%, type C 15%, type B 8%). A total of 30 (58%) periprosthetic fractures with 4 (8%) interimplant femur fractures were documented. The perioperative morbidity was 64%, and the 3-month and 1-year mortality rates were 29% and 35%, respectively. The local complication rate was 6% with no documented implant failure. Of the patients who were living at home before the surgery, 62% required long-term accommodation in residential or nursing homes after dicharge from the hospital or short-term rehabilitation.

Conclusions:

Geriatric patients with distal femur fractures face a high perioperative mortality. Osteosynthesis with distal femur locking plates is a reliable technique that can be used in various fracture patterns including periprosthetic and interimplant fractures.

Radiation Dose Reduction of Computed Tomography in Complex Distal Femur Fractures: A Cadaver Study to Develop a Low Dose Scanning Protocol

CONTEXT

Recent advances in diagnostic imaging have made computed tomography (CT) a widely used test in trauma patients. Consequently, the collective radiation burdened sustained by this patient population has increased substantially. The purpose of this cadaveric study was to determine if a significantly lowered CT radiation dose protocol would provide adequate imaging studies for the surgeon, using the distal femur as a model.

METHODS

Ten adult cadaveric knee specimens were used to create Orthopaedic Trauma Association (AO/OTA) 33-C3 distal femur fractures with associated coronal plane Hoffa fractures and varying intra-articular displacements. Using a single CT scanner, each cadaver was scanned at 5 separate protocols defined by sequentially lowered radiation doses, the highest of which was one-third the value of our institution's current protocol. These images were then evaluated by fellowship-trained orthopedic surgeons, an orthopedic trauma fellow, and residents. Observer reliability and confidence levels were calculated for measuring fracture displacement, assessing the quality of 3D reconstructions, and developing treatment plans.

RESULTS

Across all reviewers and specimens, there was an average difference of 0.66 millimeters (mm) between the measured fracture gap and true fracture gap. The highest intraclass correlation coefficient (ICC) calculated for the inter-rater reliability of gap measurements was 0.983 at 75 mAs (95% CI: 0.955-0.996), followed by 0.973 (95% CI: 0.930-0.993) and 0.958 (95% CI: 0.896-0.988) at 15 mAs and 60 mAs, respectively. All 3D reconstructions obtained at 75 mAs and 45 mAs values (N = 8) were of acceptable imaging quality to all reviewers, while only 3 of 4 3D reconstructions obtained at 15 mAs were considered acceptable. There was no difference in treatment plans across all reviewers, regardless of radiation dose.

CONCLUSIONS

In summary, our results indicate that CT scans of complex distal femur fractures at one-third the amount of radiation exposure may provide adequate imaging necessary to develop an appropriate treatment plan. At significantly lowered doses, the reviewers were able to accurately measure the amount of fracture displacement and identify the presence of each Hoffa fracture. Future studies are necessary to compare this protocol's diagnostic capacity and limitations in evaluating complex fractures with that of our institution's standard protocol in a clinical setting.