Beyond mechanism: comparable complication rates in high- and low-energy distal femoral fractures suggest complex risk interplay

详细

Purpose: Distal femoral fractures traditionally present in two distinct populations: young males with high-energy trauma and elderly females with low-energy injuries. Despite inherent differences between these groups, direct outcome comparisons remain limited. This study investigated whether injury mechanism influences complication rates in surgically treated distal femoral fractures.

Methods: A retrospective review of surgically treated distal femoral fractures at a single center for a decade was conducted. Cases were categorized into high- and low-energy mechanisms. Primary outcomes included nonunion, infection, and hardware failure. Patient demographics, comorbidities, fracture characteristics, and surgical techniques were analyzed.

Results: Of 162 cases analyzed, annual incidence of distal femoral fractures was 9.56/million. 51.2% were low-energy injuries. The low-energy group was significantly older (68.5±14 vs 41.3±17 years, p<0.001), predominantly female, and had more comorbidities. The high-energy group showed male predominance and higher smoking rates. AO/OTA 33-A was the most common fracture pattern (58.6%). Plate fixation was utilized in 66.0% of cases. Overall complication rate was 12.3%, including nonunion (6.8%), infection (3.1%), and hardware failure (2.5%). Notably, complication rates were comparable between high- and low-energy groups (p=0.551).

Conclusions: Despite distinct demographic profiles and injury mechanisms, complication rates were similar between groups, suggesting a complex balance of risk factors. This finding challenges the assumption that injury mechanism predicts outcomes and emphasizes the importance of personalized perioperative care addressing patient-specific risk factors rather than injury mechanism alone.

全文:

Background

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 [13].

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 [13, 21]. 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 [9] - the path to achieving these objectives varies considerably. The complexity of management is further compounded by significant complications, including malunion, non-union, infection, and hardware failure, often necessitating challenging revision surgeries [5, 14, 22, 25]. These complications not only impact patient outcomes and quality of life but also pose substantial healthcare resource challenges [31]. Current literature reports considerable variation in complication rates, with non-union rates spanning 6-38% and infection rates ranging from 3-15% [3, 11, 15, 32]. 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 [1, 28]. 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. This study addresses this knowledge gap by analyzing a substantial decade-spanning cohort, offering valuable insights into the nuances of distal femoral fractures and their complications across different patient populations.

Methods

Study Design: This single-center retrospective 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 initially identified 200 adult patients with surgically treated distal femoral fractures through hospital records using ICD-9 codes. All diagnoses were independently verified through detailed medical record review and preoperative radiographic assessment. After applying exclusion criteria (17 periprosthetic fractures, 14 bilateral fractures, 4 miscoded cases, 2 pre-operative mortalities, and 1 primary amputation due to vascular compromise), 162 cases were included in the final analysis [Figure 1].

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 [4]. 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.

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 [17].

Statistical analysis: Bivariate analysis of the two groups was performed using independent sample T-tests for the continuous variables and Pearson chi-square and Fisher exact test for the categorical variables. A p-value of <0.05 was considered significant. Statistical analysis was performed using the SPSS software package, version 26.0 (SPSS, IBM. Armonk, NY, USA). During the preparation of this work the authors used chatGPT language model to improve readability and language. After using this tool/service, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

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 mean age was 55 years (SD±20.9), with significant age disparity between groups: low-energy cases averaged 68.5 years (SD±14) compared to 41.3 years (SD±17) 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).

In the subset of patients with available BMI data (22.2%, n=36), the low-energy group demonstrated significantly higher values (29.9 vs. 23.3; 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) [Table 1].

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.

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%).

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).

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: Mean follow-up duration was 9.7 months (SD±8.3), with 60.5% of patients completing extended follow-up (>3 months). 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 [19], 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 [8]. Our data demonstrated clear peaks in young males and elderly females [19, 26], with corresponding injury mechanisms: high-energy trauma predominantly affecting young males and low-energy falls primarily involving elderly females [6, 19, 23] [Figure 2]. 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 [19, 26, 27]. This contrasts with some reports suggesting higher rates of complex articular fractures (AO/OTA 33-C) in high-energy trauma [24], 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 [7]. The preference for plate fixation at our institution reflects broader trends in the literature [18, 19, 27]. Notably, our data corroborates previous studies showing comparable outcomes between intramedullary nailing and locking plates [10, 16, 20], 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 Zlowodzki's systematic review findings of 6.0% across 1,670 cases [31]. Similarly, our deep infection rate of 3.0% corresponds well with the literature rate of 2.7% [2, 12, 29–31].

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 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.