Best of Both Worlds? Fixation of Distal Femur Fractures with the Nail-Plate Construct. Patient-Reported Outcomes and One-Year Results in a Heterogenous Population

doi:10.21203/rs.3.rs-2963784/v1

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Research Article

Best of Both Worlds? Fixation of Distal Femur Fractures with the Nail-Plate Construct. Patient-Reported Outcomes and One-Year Results in a Heterogenous Population

https://doi.org/10.21203/rs.3.rs-2963784/v1

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Objectives

Distal femoral fractures are a significant injury sustained by low- and high-energy trauma. Common treatment practices are lateral locking plate or intramedullary nail fixation, with disadvantages including risk of non- and mal-union and limited post-operative weightbearing status. Combining both techniques as a nail-plate construct (NPC) theoretically achieves enhanced fixation to allow immediate weightbearing. This study examines the functional, radiographic, and patient-reported outcomes of distal femur NPC fixation.

Methods

Single-centre combined prospective and retrospective study including all patients > 18 years who sustained distal femur fractures treated with NPC. The primary outcome was radiographic union and malunion at minimum one-year follow-up. Secondary outcome measures included patient reported outcome measures, post-operative mobility, length of stay and complications.

Results

Sixteen patients were included in the study. Rate of radiographic union was 100%. There was no case of malunion. All patients were allowed to full weight bear immediately post-operatively. Mean length of stay was 9.50 days, with 37.5% of patients discharged directly home. The majority (85.7%) of patients returned to pre-injury mobility. Early post-operative complications occurred in three patients. Three patients returned to theatre. The mean EQ-5D-5L index value was 0.713, with 71.4% describing no problems with self-care and 85.7% reporting no or slight problems with usual daily activities.

Conclusions

The NPC provided stable fixation permitting full weightbearing post-operatively with no cases of non- or malunion. Return to pre-injury mobility and activity are encouraging. Based on these results we support the use of nail-plate construct fixation in the management of distal femur fractures.

distal femur fracture

nail plate fixation

nail plate construct

nail plate combination

linked construct

retrograde intramedullary nail

locked lateral plating

Native and periprosthetic distal femur fractures are a significant injury associated with high morbidity and mortality rates.¹ Classically bimodal in distribution, young patients sustain these fractures from high-energy trauma whilst elderly patients commonly suffer low-energy mechanisms in the setting of osteoporosis.^1,2 In the context of a rapidly ageing population and increasing numbers of total knee arthroplasty (TKA), the rate of distal femur fractures is rising.^1,3,4

The one-year mortality rate of distal femur fractures can be as high as 25%.⁵ The risk of venous thromboembolism in these patients is also up to 25%.⁶ Surgically managed distal femur fractures have improved post-operative mobility.^7,8 Early mobilisation and ability to full weight bear have been shown to reduce mortality rates, post-operative complications and in-hospital length of stay.^9,10

Locked lateral plating (LP) and intramedullary nailing (IMN) are accepted methods for managing distal femoral fractures.⁴ However, issues exist with their independent use. There is no consensus on the safety of full weight bearing post-operatively. Elderly patients generally cannot adhere to partial or non-weightbearing instructions. This can result in protracted hospital admissions and thereby greater hospital costs and associated nosocomial complications.

Used as single fixation methods, LP and IMN have non-union rates of 3.6–27.5%.^7,11 Standalone LP has a 7.6% malunion rate and a 13.3% rate of secondary surgical procedures.⁷ Intra-medullary nailing has a 16.4% malunion rate and 9.1% rate of secondary surgical procedures.⁷ Dual plate fixation has been heralded as an alternative fixation technique, however non-union and delayed union rates reach 12.5% and 33.3% respectively.¹²

The nail-plate construct is a more recently described method for distal femur fractures, combining LP and IMN to provide biomechanically advantageous fixation. This construct has the potential to reduce the risk of non- and mal-union and allows patients to mobilise immediately post-operatively without weightbearing restrictions. This in turn could lead to improved post-operative mobility thereby reducing risk of post-operative morbidity and mortality.

The primary aim of this study is to investigate radiographic union and malunion rates in distal femur fractures managed with NPC. This will be the first study to investigate PROMs in this population. The authors also explore post-operative mobility, morbidity and mortality rates.

Patients included in this study were older than 18 years of age who sustained acute native or periprosthetic distal femur fractures (OTA 33-A, 33-B, 33-C) that were managed with NPC technique fixation. Exclusion criteria included age under 18 years, management for mal- or non-union, and periprosthetic fracture of distal femur tumour prosthesis.

The primary outcome measures were radiographic union and malunion at minimum one year follow-up. One-year follow-up was selected to reflect minimum follow-up in previously published clinical research on NPC distal femur fixation.^11,13 Radiographic union was assessed by two researchers with minimum four years’ experience in orthopaedic surgery using the modified RUST score. The modified RUST score has been validated for use in distal femur fractures, with a score of 11 dictating radiographic union.¹⁴ Malunion was defined as ≥5o to allow comparison to previous studies on distal femur fracture fixation.⁷

Secondary outcome measures were pre- vs post-operative mobility, day of first-time mobilisation post-operatively, post-operative weightbearing status, post-operative length of stay (LOS), discharge destination and any post-operative complication or return to theatre.

Patient reported outcome measures were recorded in the form of the EuroQol 5 Dimensions (EQ-5D-5L). This is a validated, generalised tool used to measure quality of life across five domains: mobility, self-care, usual activities, pain, and depression.¹⁵

All operations were performed by two Fellowship-accredited Orthopaedic Surgeons at a regional referral, Level 5 base hospital in Australia. Data was collected prospectively and retrospectively dependant on when patients were recruited to the study. Follow-up was performed via either face-to-face or telemedicine appointment at minimum one year post-operatively.

Demographic information included age, sex, and body mass index. Pre-injury functional status was recorded, including mobility (i.e. use of aids) and assistance (i.e. from another individual). Mechanism of injury (low- and high-energy), native or periprosthetic fracture, pathological or non-pathological fracture, operating surgeon and use of bone graft were recorded. Data analysis was performed using Microsoft® Excel (2021).

Surgical Technique

The nail and plate implants were ‘fixed’ to one another by introducing at least one locking screw through both the distal locking holes of the nail and plate. The rationale being that this creates a more rigid and stable combined construct. Nailing techniques were either antegrade or retrograde dependent upon fracture configuration and whether an ‘open box’ was present in patients with total knee arthroplasty.

Patient Position and Approach

One surgeon preferred the use of a supine traction table for antegrade nailing. All other patients were positioned supine on a standard radiolucent operating table. A lateral, or lateral parapatellar in the case of intra-articular distal fractures, approach to the femur was performed for reduction and plate fixation. A midline incision with medial parapatellar approach was used for retrograde femoral nailing. Antegrade femoral nailing was performed via standard lateral approach with trochanteric entry point.

Fixation Technique

Fracture reduction and temporary fixation was achieved by either direct or indirect technique through a lateral or parapatellar approach. Reduction was confirmed visually and with fluoroscopy. Nail and plate constructs were linked by placing a screw through the distal locking holes of each implant. Refer to the legend for Figs. 1–7 for completeness.

Post-operative Protocol

All patients received prophylactic antibiotics on induction, as well as chemical DVT prophylaxis peri-operatively. All patients were allowed to immediately full weight bear and were encouraged to range their hip and knee as tolerated.

A total of 17 NPC patients were identified for this study. One patient was excluded as the indication for surgery was infected non-union following lateral plate fixation, with treatment requiring temporary cement spacer followed by staged bone grafting using a custom-printed implant.

Patient demographics are displayed in Table 1. Of the 16 patients included, six had native distal femur fractures, eight had periprosthetic fractures proximal to a total knee arthroplasty and two had distal femur fractures distal to a total hip arthroplasty. AO/OTA Classifications are shown in Table 2.

Table 1

Patient Demographics
Age in years, median (range)	72.5 (30–93)
Gender female, number (%)	11 (69)
Body Mass Index, mean (std deviation)	29.1 (5.63)
Low-energy fracture, number (%)	14 (87.5)
Closed fracture, number (%)	15 (93.8)

Table 2

AO/OTA Fracture Classification
AO/OTA Classification	Frequency
33-A1	3
33-A2	1
33-A3	1
33-C1	1
33-C3	2
33-V3B	5
33-V3C	3

Mean follow-up was 17.5 months (SD 5 months). At follow-up, 2 patients were identified as deceased in community from causes not immediately related to their surgical care. The remaining 14 patients all responded to their follow-up questionnaire at minimum 1 year.

Of the 11 patients that had x-rays performed at minimum 1-year post-operatively, the radiographic union rate was 100%. There was no loss of position or implant failure resulting in malunion. Interobserver agreement on non-union and mal-union was 100%.

Six patients (42.9%) mobilised day 1 post-operatively, with 78.6% of patients having mobilised by day 2. The mean LOS was 9.50 (SD 8.16) days. The mean LOS reduced to 7.80 (SD 4.68) days on removal of an outlier that had an extended ICU stay for pre-existing respiratory disease.

Six patients (37.5%) discharged directly home, one returned to a nursing home and nine were transferred to rehabilitation.

At one year, 12 patients (85.7%) had no change in pre- and post-operative use of mobility aid. One patient went from needing no aids to mobilising with a single-point walking stick. The other patient went from using a 4WW to requiring a wheelchair.

Pre-operatively, no patients required assistance from another individual to mobilise. At follow-up, 85.7% continued to mobilise without assistance post-operatively. One patient required stand-by-assistance, whilst another required active assistance.

Six post-operative complications occurred in 5 patients. Three patients (18.8%) required return to theatre. Two patients returned to theatre for post-operative infection. The other patient experienced irritation from implant and underwent removal of distal femoral plate one year after index fixation. Three patients (18.8%) experienced early post-operative complications; pulmonary embolus diagnosed day 1 post-operatively, hospital-acquired pneumonia and urosepsis.

Table 3 reflects the patient-reported outcome measures (EQ-5D-5L) at minimum 1 year post-operatively. Fifty percent of patients described no issues with mobility with a further 28.6% reporting slight issues with mobility. Regarding self-care, 71.4% described no problems and 21.4% reported slight issues. The majority (85.7%) of patients reported no or slight problems with usual daily activities. Six patients (42.9%) reported no pain, with no patients describing severe or extreme pain.

Table 3

EQ-5D-5L patient reported outcome measures for individual Domains.
Domain	Mobility	Self-Care	Usual Activities	Pain / Discomfort	Anxiety / Depression
1 - No issues	7	10	3	6	8
2 - Slight issues	4	3	9	5	4
3 - Moderate issues	1	0	1	3	2
4 - Severe issues	0	0	1	0	0
5 - Extreme issues	2	1	0	0	0

The evidence available on the use of the NPC in acute distal femur fractures consists of biomechanical and small clinical studies, but the results to date are highly promising. To the authors’ knowledge, no studies have yet investigated malunion rates or patient-reported outcome measures (PROMs) in this patient cohort.

There is no consensus on the ideal surgical management of distal femur fractures. Nail fixation allows minimal fracture site disruption and stimulated healing from reaming of the intramedullary canal.¹⁶ With strong biomechanical properties, fixed-angle plates are designed for osteoporotic bones.¹⁶ However, biomechanical studies have shown that as a load-bearing device lateral plating is more likely to result in implant failure than IMN.³ The same biomechanical studies have also revealed high risk of catastrophic failure of the bony cortex in fractures fixed with a load-sharing IMN.³ Isolated lateral plate fixation has non-union rates of 8.8% and mal-union rates of 7.6%.⁷ Similarly, IMN fixation has non-union and mal-union rates of 3.6% and 16.4% respectively.⁷

Combining the advantages of a lateral locking construct with a load-sharing central beam results in energy being more evenly distributed between bone and implants.³ Additionally, linking the constructs with locking screws and spanning the femur allows for smoother transition of forces and therefore more stable, early weightbearing.³ Whilst weightbearing post-operatively risks implant failure and malunion in isolated fixation techniques, the NPC permits immediate weightbearing.

Liporace et al. used NPC to treat 15 patients with either native or periprosthetic distal femur fractures.³ At follow-up, all patients achieved bony union and remained ambulatory. Kanabur et al investigated 8 patients who underwent NPC fixation for distal femur periprosthetic and interprosthetic fractures, achieving fracture union in all patients.¹³ Garala et al managed 27 patients with nail-plate fixation with union in all patients and no implant failure at follow-up.¹¹

Our study revealed a union rate of 100%, consistent with the aforementioned NPC studies.^3,11,13. Interestingly, two patients in this cohort were treated for pathological fracture secondary to multiple myeloma. Despite a non-union rate of 33% in long bone fractures secondary to multiple myeloma, both these patients achieved radiographic union.¹⁷ There were no cases of malunion or implant failure in our study.

These results compare favourably to the significant mal- and non-union rates in isolated LP or IMN fixation techniques.^7,11 Our study supports that NPC fixation for distal femur fractures yields excellent radiographic union results in the setting of immediate full weightbearing.

The EQ-5D-5L mean index value was 0.713 (SD 0.195) at minimum one-year follow-up, weight-adjusted for the general Australian population. This compares favourably to a study that surveyed isolated LP or IMN fixation at 4 months post-operatively, scoring only 0.37 and 0.38 respectively.¹⁶ Another study reported an EQ-5D index of 0.70 for LP and 0.76 for IMN fixation at one year.¹⁸ However, the average age in this comparative study was 19.5 years younger than our cohort, which likely had a significant influence on outcomes. A study in patients > 65 years of age managed with either LP or IMN revealed EQ-5D-5L index value < 0.40 at 9-month follow-up.¹⁹ Despite limited studies for comparison, these results indicate that patient reported outcomes in nail-plate fixation may be superior to isolated fixation methods.

The majority of our patients had no change in their use of mobility aids from pre- to post-operatively. Fifty percent of patients described no problems with their mobility at one-year follow-up, whilst another 28.6% reported only slight issues. Self-care did not pose any issue in 71.4% of patients and 85.7% of patients reported no or slight problems with usual daily activities. Most of our patients returned to independent mobility and activities of daily living with no or minimal impediment. This is likely a reflection that the early weightbearing NPC fixation provides allows a more effective period of rehabilitation and therefore return to pre-morbid function.

Early weightbearing and mobilisation reduces the rate of post-operative non-surgical complications and mortality.¹⁰ In our cohort, 78.6% of patients had mobilised by day 2. In patients aged > 50 years our study had a one-year mortality of 14.3%, which compares favourably to a rate of 18–25% in isolated LP or IMN fixation.^5,20

In the setting of elderly patients who have weightbearing limitations post-operatively, the length of stay in distal femur fractures managed with isolated LP or IMN is 26–29 days.^19,20. Our mean length of stay was 9.5 days, including an outlier patient that had an extended stay of 35 days for pre-existing respiratory disease.

Similarly, early post-operative complications were lower in our study compared to patients managed with isolated fixation technique. Lateral plate fixation of distal femur fractures have early post-operative complications of 20-37.5%, including venous thromboembolism, respiratory complications, cardiac complications, and others.^5,18 Our study had a rate of 18.8%.

Two patients returned to theatre for post-operative infection. One patient underwent debridement, lifelong antibiotic suppression and achieved fracture union. The other patient underwent removal of plate and debridement, achieved fracture union and completed antimicrobial therapy. Interestingly, both these patients had undergone revision from short IM nails to total hip arthroplasty, which were then complicated by distal femur periprosthetic fracture. There is a significant risk of infection in revision surgery, with one study reporting a 5.8% rate of infection in revision from IM nail fixation to total hip arthroplasty.²¹ Additional risk factors in these patients included diabetes, emphysema and renal cancer. Our reduced length of stay and lower rates in morbidity and mortality may be attributable to improved mobility in the immediate post-operative period with NPC fixation.

We recognise that there are limitations to our study. This was a single-centre study in a regional hospital and thus the sample size is small. However, distal femur fractures make up only 0.4% of all adult fractures and therefore studies across multiple centres and greater timeframes are required for larger numbers.¹ With mean follow-up of 17.5 months, this is considered a short-term follow-up publication. However, this follow-up period is comparable to other literature on distal femur operative fixation. To our knowledge, this is the first paper investigating PROMs and malunion rates in distal femur NPC fixation. The authors look forward to further investigating NPC technique with a greater sample size and longer follow-up period.

The nail-plate construct provides stable fixation of the distal femur fracture with the benefit of immediate full-weightbearing post-operatively. In our patient cohort, there were no cases of non- or malunion. In an elderly population this allows improved mobility post-operatively, which may result in reduced length of stay, early complications, and mortality rates at one year. Therefore, the authors support the use of nail-plate construct fixation in distal femur fractures and look forward to larger, prospective trials investigating this technique.

Ethical Approval

Ethics approval was obtained from the New South Wales Health Ethics Committee via Research Ethics and Governance Information System (ETH11681).

Consent to Participate and Publish

Informed consent for study participation and research publication was obtained from all patients.

Competing Interests

The authors declare no conflict of interest.

Authors’ Contributions

B.P. and H.D. contributed to the concept of this research. B.P. and A.W. acquired and analysed the data. All authors interpreted the data. B.P. wrote the main manuscript text and prepared all tables, with A.W. assisting in preparation of figures. All authors reviewed the manuscript and approved the current version for publication. All authors agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Funding

The authors have no funding to disclose. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Availability of Data and Materials

The dataset supporting the conclusions of this article is included within the article and its additional file.

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No competing interests reported.

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Best of Both Worlds? Fixation of Distal Femur Fractures with the Nail-Plate Construct. Patient-Reported Outcomes and One-Year Results in a Heterogenous Population

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Version 1

Abstract

Objectives

Methods

Results

Conclusions

Figures

Introduction

Materials and Methods

Surgical Technique

Patient Position and Approach

Fixation Technique

Post-operative Protocol

Results

Discussion

Conclusion

Declarations

References

Additional Declarations

Status:

Version 1