Только ли механизм травмы? Сопоставимая частота осложнений при высоко- и низкоэнергетических переломах дистального отдела бедренной кости как показатель сложной взаимосвязи факторов риска

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INTRODUCTION

Distal femoral fractures, though comprising only 1% of all fractures and 3-6% of femoral fractures, represent a significant clinical challenge warranting increased attention as demographic shifts predict a rising incidence, particularly with the expanding global geriatric population [1, 2].

These fractures present a unique dichotomy in their demographic distribution and mechanism of injury. The first group predominantly consists of young males sustaining high-energy trauma, while the second encompasses elderly females typically experiencing low-energy injuries [1, 2]. This distinct bimodal distribution offers a compelling opportunity to examine how different injury mechanisms and patient characteristics influence outcomes.

The current treatment landscape encompasses a spectrum of interventions, ranging from conservative management to various surgical fixation techniques. While the fundamental goal remains consistent across all approaches — maintaining joint architecture and ensuring articular stability [3] — the path to achieving these objectives varies considerably. The complexity of management is further compounded by significant complications, including malunion, nonunion, infection, and hardware failure, often necessitating challenging revision surgeries [2, 4, 5, 6]. These complications not only impact patient outcomes and quality of life but also pose substantial healthcare resource challenges [7, 8, 9]. Current literature reports considerable variation in complication rates, with nonunion rates spanning 6-38% and infection rates ranging from 3-15% [10, 11, 12, 13]. However, there remains a notable gap in comparative analyses between demographic groups.

The inherent physiological, mechanical, and demographic differences between these two distinct patient populations suggest potential variations in complication patterns and rates [14]. Understanding these variations could prove instrumental in developing targeted treatment algorithms and optimizing resource allocation. Given the relative infrequency of these fractures and their significant impact, there is a compelling need for comprehensive research in this area.

The aim of this study — to compare complication rates between surgically treated high- and low-energy distal femoral fractures and to assess whether injury mechanism independently influences outcomes.

METHODS

Study design

This single-center retrospective cohort study was conducted following institutional committee approval, analyzing outcomes of surgically treated distal femoral fractures over an eleven-year period (January 2006 — March 2017).

Patient selection and data collection

We identified 200 patients with surgically treated distal femoral fractures at Rambam Health Care Campus between January 2006 and March 2017 using ICD-9 codes. Inclusion criteria were: age ≥ 18 years; acute distal femoral fractures (AO/OTA 33 group) treated with definitive surgical fixation. All diagnoses were verified through detailed medical record review and preoperative radiographic assessment. Exclusion criteria were: periprosthetic fractures; bilateral fractures; miscoded cases not representing distal femoral fractures; preoperative mortality; and primary amputation due to vascular compromise. After applying these criteria, 162 patients remained for final analysis (Figure 1).

 

Figure 1. Patient selection flowchart

 

Cases were stratified by injury mechanism into two groups: low-energy trauma (falls from standing height) and high-energy trauma (motor vehicle accidents or falls from above standing height). Comprehensive data collection included demographic characteristics, lifestyle factors, and major comorbidities such as diabetes, hypertension, cardiac conditions, and chronic renal failure. Additionally, we documented fracture characteristics and associated injuries, which were quantified using the Injury Severity Score [15]. Fracture classification was performed using the AO/OTA system, with independent verification by two authors to ensure reliability.

Post-operative protocol

A standardized rehabilitation protocol was implemented, consisting of an initial six-week non-weight-bearing period followed by a subsequent six-week partial weight-bearing progression. The median follow-up duration was 7 months [4; 12], with 60.5% of patients completing extended follow-up (> 3 months).

Outcome measures

Complications were defined according to standardized criteria. Nonunion was defined as cessation of consolidation progress after 8 months or lack of radiographic improvement over 3 consecutive months. Hardware failure was characterized as implant breakage or significant radiological loosening resulting in re-displacement, shortening, or fracture movement. Surgical site infection was documented as microbial contamination within one year of implant placement [16].

Statistical analysis

Continuous variables were assessed for normality using the Shapiro-Wilk test and were found to be non-normally distributed. Therefore, they are presented as median (Me) with interquartile range [Q₁; Q₃] and compared using the Mann-Whitney U test. Categorical variables are presented as counts and percentages and compared using Pearson’s chi-square or Fisher’s exact test, as appropriate. A p-value < 0.05 was considered statistically significant. All analyses were performed using SPSS version 26.0 (IBM, Armonk, NY, USA).

RESULTS

Demographics and lifestyle characteristics

The final cohort comprised 162 adult cases with surgically treated distal femoral fractures, distributed between low-energy (51.2%) and high-energy (48.8%) mechanisms. The overall median age was 57.9 years [35.4; 73.2], with significant age disparity between groups: low-energy cases had median age of 70.0 years compared to 36.0 in high-energy cases (p < 0.001). Gender distribution showed significant variation, with female predominance in the low-energy group and male predominance in the high-energy group (p < 0.001) (Table 1). The age and sex distribution of the cohort demonstrates peaks in young males and elderly females (Figure 2).

 

Table 1

Patient characteristics at baseline

Parameter	Low-energy group	High-energy group	p-value
Age, years, Me [Q1; Q3]	70.0 [59.3; 79.7]	36.0 [26.8; 53.5]	< 0.001
Gender (F), n (%)	71 (85.5)	27 (34.1)	< 0.001
BMI, kg/m², Me [Q1; Q3]	29.1 [24.9; 33.3]	23.1 [20.7; 27.5]	0.002
Smoker, n (%)	8 (30.7)	22 (70.9)	0.002
Co-morbidities, n (%)
Diabetes	22 (26.5)	9 (11.3)	0.015
Hypertension	32 (38.5)	9 (11.3)	< 0.001
Cardiac condition	17 (20.4	2 (2.5)	< 0.001
Renal condition	2 (2.4)	1 (1.2)	0.589

BMI — body mass index.

Statistically significant values are shown in bold.

 

Figure 2. Distribution of the cohort with the subdivision between sexes. F — female, M — male

 

In the subset of patients with available BMI data (22.2%, n = 36), the low-energy group demonstrated significantly higher median values (29.1 vs 23.1; p = 0.002). Smoking status, documented in 35.1% of cases (n = 57), was significantly more prevalent in the high-energy group (p = 0.002). Comorbidity analysis revealed significantly higher rates of diabetes (p = 0.015), hypertension (p < 0.001), and cardiac diseases (p < 0.001) in the low-energy group (see Table 1).

Fracture characteristics

Fracture laterality showed equal distribution between groups (p = 0.542). According to AO/OTA classification, type 33-A fractures predominated (58.6%), followed by type 33-B (30.3%) and type 33-C (11.1%). Detailed characteristics of the fractures are presented in Table 2.

 

Table 2

Fracture and fixation methods distribution

Parameter	Low-energy group		High-energy group		p-value
	n	%	n	%
AO/OTA classification					0.921
33-A	50	60.2	45	56.9
33-B	9	10.8	9	11.3
33-C	24	28.9	25	31.6
Injury characteristics
Open fracture	0	0.0	18	22.8	< 0.001
Injury Severity Score					< 0.001
Moderate	0	0.0	54	68.4
Severe	0	0.0	16	20.3
Critical	0	0.0	9	11.4
Fixation method					0.004
Plate	57	68.6	50	63.3
Nail	24	28.9	15	19.0
K-Wire	1	1.2	0	0.0
Screws	1	1.2	4	5.1
External fixator	0	0.0	10	12.7

Statistically significant values are shown in bold.

 

Surgical management

All procedures were performed within 7 days of injury. Plate fixation was the predominant surgical technique, employed in 107 cases (66.0%). Detailed fixation method distribution is presented in Table 2.

Complications and outcomes

The overall complication rate was 12.3% (n = 20), comprising nonunion (6.8%), infection (3.1%), and hardware failure (2.5%). Notably, complication rates showed no significant difference between high and low-energy groups (p = 0.551) (Table 3), surgical techniques (p = 0.445), open fractures (p = 0.177), or injury severity scores (p = 0.281).

 

Table 3

Complication rates

Complication	Low-energy group		High-energy group		p-value
	n	%	n	%
Infection	1	1.2	4	5.1
Nonunion	6	7.2	5	6.3
Hardware failure	2	2.4	2	2.5
Total	9	10.8	11	13.9	0.551

 

Management of nonunion cases (n = 11) involved revision surgery performed 6-12 months post-initial procedure. Treatment strategies included isolated bone grafting (5 cases), plating (4 cases), and combined plating with bone grafting (2 cases). All revision cases demonstrated radiographic healing within 3 months post-revision.

Post-operative outcomes

All patients achieved functional range of motion, defined as absence of extension lag and minimum flexion of 110 degrees, with no discrepancy in leg length at final follow-up.

DISCUSSION

Our study of distal femoral fractures, conducted at a major medical center serving approximately two million residents, revealed an incidence of 9.56 cases per million per year. This finding aligns with existing literature and reinforces the relative rarity of these fractures [17], underlining the importance of comprehensive analysis to better understand their epidemiology.

The demographic distribution in our cohort strongly supports the bimodal pattern theory, contrasting with Court-Brown and Caesar’s original unimodal distribution model [18]. Our data demonstrated clear peaks in young males and elderly females, as in several other studies [17, 19], with corresponding injury mechanisms: high-energy trauma predominantly affecting young males and low-energy falls primarily involving elderly females [17, 20, 21]. The low-energy group predictably exhibited a higher prevalence of comorbidities, reflecting the age-related health challenges in this population.

Regarding fracture patterns, our finding of AO/OTA 33-A predominance showed no correlation with injury mechanism, consistent with several previous studies [17, 19, 22]. This contrasts with some reports suggesting higher rates of complex articular fractures (AO/OTA 33-C) in high-energy trauma [23], highlighting the complex nature of fracture pattern determinants.

The mean follow-up period of 9.7 months, while shorter than some published series, proved sufficient for assessing primary outcomes and complications. This duration adequately captured the critical healing period, as evidenced by our observation that all revision cases achieved union within 3 months post-revision. Moreover, the local healthcare structure, where patients with persistent problems remain in follow-up while those achieving satisfactory outcomes often return to community care, suggests that our complication rates likely represent a comprehensive capture of significant adverse events. This follow-up pattern reflects real-world clinical practice and provides valuable insights into the actual trajectory of these injuries.

Our findings regarding surgical management align with current evidence supporting operative intervention, particularly in older patients [8]. The preference for plate fixation at our institution reflects broader trends in the literature [17, 22, 24]. Notably, our data corroborates previous studies showing comparable outcomes between intramedullary nailing and locking plates [25, 26, 27], supporting surgical decision-making based on individual patient and fracture characteristics rather than rigid protocol-based approaches.

Our overall complications align with published data, with nonunion rates of 6.7% matching M. Zlowodzki’s systematic review findings of 6.0% across 1.670 cases [7]. Similarly, our deep infection rate of 3.0% corresponds well with the literature rate of 2.7% [7, 28, 29, 30].

A key finding of our study was the comparable complication rates between high- and low-energy groups (p = 0.551), which presents an intriguing paradox given their distinctly different demographic and clinical profiles. Our observations suggest a compelling hypothesis about the equilibrium of risk factors between these groups. The high-energy group faced challenges from severe initial soft tissue trauma, higher smoking rates (p = 0.002), and potentially more complex injury patterns, while the low-energy group contended with reduced physiological reserves, increased comorbidities, and potentially compromised bone quality. This balance of competing risk factors may explain the similar outcomes between groups. For instance, while advanced age and comorbidities in the low-energy group might predispose to complications, the increased soft tissue damage and higher smoking rates in the high-energy group could pose comparable risks through different mechanisms.

This finding carries significant clinical implications. First, it suggests that the traditional assumption of higher complication rates in either group may need reconsideration. Second, it emphasizes the importance of individualized risk assessment rather than relying solely on injury mechanism as a predictor of complications. Third, it highlights the need for careful preoperative optimization and meticulous surgical technique in both groups, as neither appears to have an inherent advantage in terms of complication risk.

Study limitations

Study limitations include its retrospective, single-center design and incomplete data collection for certain variables. However, the substantial cohort size and comprehensive complication analysis provide valuable insights into the management of these challenging fractures. Future prospective studies incorporating patient-reported outcomes would further enhance our understanding of these injuries.

CONCLUSIONS

Our study demonstrates that despite distinct demographic profiles and injury mechanisms in distal femoral fractures, complication rates remain comparable between high- and low-energy trauma groups. This finding challenges traditional assumptions about outcome predictors and emphasizes that each population faces unique risk factors that may ultimately balance out: soft tissue damage and higher smoking rates in the high-energy group versus reduced physiological reserves and increased comorbidities in the low-energy group. These results underscore the importance of personalized perioperative care strategies that address patient-specific risk factors rather than relying primarily on injury mechanism. Future research could further elucidate the complex relationship between patient characteristics, injury mechanisms, and outcomes in these challenging fractures.

Об авторах

Снир Бальзиано

Chaim Sheba Medical Center at Tel Hashomer

Автор, ответственный за переписку.
Email: SBalaziano@gmail.com
ORCID iD: 0000-0002-8232-8602

MD

Израиль, г. Рамат-Ган

Эяль Джинезин

Rambam Health Care Campus

Email: Eyalgin@gmail.com
ORCID iD: 0000-0002-1548-7865

MD

Израиль, г. Хайфа

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