Comparison of combined femoral nail and plate fixation versus dual plate fixation in the treatment of AO/OTA 33C distal femoral fractures

Abstract

This study aimed to compare the clinical outcomes of retrograde intramedullary nailing combined with a lateral locking plate versus dual plating (medial and lateral locking plates) in the treatment of AO/OTA 33C distal femoral fractures. A retrospective analysis was conducted on 78 patients treated between June 2017 and December 2022. Patients were divided into two groups: the nail-plate group (n = 42) and the dual-plate group (n = 36). Outcome measures included intraoperative blood loss, operative time, time to weight-bearing, bone union time, visual analogue scale (VAS) scores, hospital for special surgery (HSS) scores at final follow-up, knee range of motion (ROM), and complication rates. No significant differences were observed between the groups in terms of blood loss, operative time, time to weight-bearing, bone healing time, or follow-up duration (P > 0.05). Final follow-up assessments revealed no significant differences in VAS scores, HSS scores, or knee ROM (P > 0.05). The nail-plate group experienced five complications: one delayed union, two infections, one case of knee stiffness, and one case of limb shortening. The dual-plate group reported six complications: one delayed union, one nonunion, one infection, one case of knee stiffness, one malalignment, and one case of limb shortening. Complication rates did not differ significantly between groups (P > 0.05). No implant failures were observed in either group. Both fixation strategies provided stable constructs, facilitated early recovery, and resulted in satisfactory functional outcomes. Retrograde intramedullary nailing with lateral plating and dual plating are both effective options for the management of complex AO/OTA 33 C distal femoral fractures.

Introduction

Distal femoral fractures represent 3–6% of all femoral fractures and approximately 1% of all fractures¹. These injuries exhibit a bimodal distribution, primarily affecting elderly patients with osteoporotic, low-energy trauma and younger individuals involved in high-energy accidents². Surgical fixation remains the standard treatment, aiming to achieve anatomical reduction, restore femoral length and alignment, and provide sufficient stability to enable early mobilization. However, the proximity of these fractures to the knee joint, along with frequent metaphyseal comminution, condylar involvement, and bone loss, significantly complicates surgical management³.

Current surgical options include retrograde intramedullary nailing⁴ less invasive stabilization system (LISS) plate⁵ and, less commonly, total knee arthroplasty⁶. Among these, LISS plate is widely used and generally yields favorable outcomes, yet it is associated with notable complications such as varus collapse, nonunion, and implant failure⁷. Furthermore, its eccentric fixation can hinder early mobilization and weight-bearing, leading to prolonged hospitalization, increased healthcare costs, and elevated risk of nosocomial complications⁸. Retrograde intramedullary nailing, another option, has shown promising results in selected cases⁹ but is limited by poor rotational stability and restricted distal fixation options. These shortcomings render it less suitable for intra-articular fractures with metaphyseal or epiphyseal comminution¹⁰. Total knee arthroplasty facilitates early weight-bearing and reduces complications such as pneumonia and thromboembolism; however, it is typically reserved for select cases due to higher costs and complication rates, particularly in older patients¹¹.

In recent years, combined fixation techniques have emerged as promising alternatives for complex distal femoral fractures^12,13. Indications include nonunion following lateral plate failure, periprosthetic fractures, medial Hoffa fractures, low transcondylar bicondylar fractures, medial bone loss, comminuted AO/OTA 33C3 fractures, and poor bone quality¹³. The two main approaches—nail-plate constructs and dual plating—have demonstrated superior biomechanical stability, lower nonunion rates, and earlier return to weight-bearing compared to single LISS plating¹⁴. Despite increasing clinical use, comparative evidence between nail-plate constructs and dual plating for AO/OTA 33 C distal femoral fractures remains limited. This retrospective study aimed to evaluate and compare the biomechanical and clinical outcomes of these two fixation strategies in managing such complex fractures.

Patients and methods

Patient selection

This retrospective study was conducted at a Level 1 trauma center from June 2017 to December 2022 in accordance with the ethical standards of the 2013 Helsinki Declaration and institutional research committee protocols. Informed consent was obtained from all patients. Inclusion criteria were defined as AO/OTA 33 C distal femur fractures, skeletally mature adults with a minimum follow-up of 12 months, and treatment with either a nail–plate construct (retrograde intramedullary nail combined with a lateral locking plate) or dual plate fixation (medial and lateral locking plates). Exclusion criteria included pathologic fractures, ipsilateral tibial fractures, multiple medical conditions contraindicating surgery, fractures complicated by nerve or vascular injury, and follow-up shorter than 12 months. Surgical treatment was determined by a senior surgeon based on fracture pattern, implant stability, and clinical expertise.

Preoperative preparation

Upon admission, patients with open fractures were promptly subjected to debridement, suturing, and temporary external fixation. Closed fractures were managed with tibial tubercle traction. Deep vein thrombosis was evaluated using ultrasound, and the injured limb was elevated. Ankle pump exercises were prescribed to reduce swelling. Surgery was scheduled following the resolution of swelling and confirmation of the absence of contraindications.

Surgical procedure

Patients were positioned supine with the knee flexed at 30°. A femoral distractor, anchored via pins in the proximal tibial metaphysis and femoral diaphysis, was employed to realign the fracture and disimpact intra-articular fragments. Fracture reduction and alignment were verified using C-arm fluoroscopy. A tourniquet was applied during all procedures.

In the nail plate group, a lateral parapatellar incision was made to expose the anterior and lateral distal femur. Intercondylar fractures were reduced and stabilized with multiple cannulated screws to reconstruct the supracondylar segment. A distal femoral LISS plate was then inserted beneath the vastus lateralis, with positioning confirmed prior to fixation using three to six locking screws distally and proximally. Retrograde femoral nailing was subsequently performed via a midline incision with a medial parapatellar approach.

In the dual plate group, LISS plate fixation was conducted as described above. Thereafter, a medial subvastus approach was used to access the medial femur. A proximal humerus locking plate, favored at our center for its anatomic contour matching the medial distal femur¹⁵ was applied.

All surgeries were performed by fellowship-trained orthopedic surgeons.

Postoperative management

Postoperatively, antibiotics were administered for 24 h. Intensive passive-assisted motion was initiated on the first postoperative day in both groups using a continuous passive motion (CPM) device for 20 min, two to three times daily. Range of motion (ROM) was adjusted based on patient tolerance, typically progressing from full extension to 70° of flexion. Passive ROM exercises were continued for a minimum of two weeks until painless active motion was achieved.

Outcome assessment

Essential parameters, including surgical duration, blood loss, and complications, were recorded. Follow-up comprised routine visits with monthly radiographic evaluations to monitor bone healing. Partial weight-bearing was initiated at two weeks, beginning with sole contact or a maximum load of 15 kg¹⁶ and adjusted according to fracture characteristics, bone quality, soft tissue condition, and patient tolerance. Pain and functional outcomes were assessed using the Visual analog scale (VAS), Hospital for special surgery (HSS) score, and knee range of motion.

Statistical analysis

Statistical analyses were performed using SPSS version 26.0. Quantitative data are expressed as mean ± standard error of the mean (SEM) and compared using the two-sample t-test. Qualitative data were presented as frequencies and percentages and analyzed with either the two-sided Fisher’s exact test or the chi-square test, as appropriate. Statistical significance was defined as P < 0.05.

Results

Table 1 presents the baseline characteristics of the two groups. The nail-plate group included 42 patients (24 males, 18 females) aged 36–68 years (mean: 51.1 ± 9.7 years). Injury mechanisms included traffic accidents (n = 14), sprains (n = 5), falls from height (n = 19), and other causes (n = 4). Fracture classifications were AO/OTA 33C1 (n = 19), 33C2 (n = 14), and 33C3 (n = 9), with 8 open and 34 closed fractures. Associated injuries included traumatic brain injury (n = 2), chest trauma (n = 4), and other fractures (n = 4). Thirteen patients had comorbidities: diabetes (n = 4), cardiovascular disease (n = 5), and respiratory disease (n = 4).

Table 1.

Baseline characteristics of two groups.

Characteristics	Nail plate group	Dual plate group	Total	P Value
Gender	42	36	78	0.535
Male (%)	24 (57.1%)	20 (55.5%)	44 (56.2%)
Female (%)	18 (42.9%)	16 (44.5%)	34 (43.8%)
Age (Years)	51.1 ± 9.7 (36 ~ 68)	51.6 ± 11.7 (30 ~ 76)	51.3 ± 10.6 (30 ~ 76)	0.251
Causes Of injury				0.996
Traffic accident (%)	14 (33.3%)	12 (33.3%)	26 (33.3%)
Fall from height (%)	19 (45.2%)	16 (44.5%)	35 (44.9%)
Sprain (%)	5 (12.0%)	4 (11.1%)	9 (11.5%)
Other injuries (%)	(9.5%)	4 (11.1%)	8 (10.3%)
AO/OAT classification				0.921
33C1 (%)	19 (45.3%)	15 (41.7%)	34 (43.6%)
33C2 (%)	14 (33.3%)	12 (33.3%)	26 (33.3%)
33C3 (%)	9 (21.4%)	9 (25.0%)	18 (23.1%)
Type of fractures				0.511
Closed fractures (%)	34 (71.4%)	30 (70.3%)	64 (70.8%)
Open fractures (%)	8 (28.6%)	6 (29.7%)	14 (29.1%)
Multiple injuries (%)				0.615
Traumatic brain injury	2 (4.8%)	1 (2.8%)	3 (3.8%)
Chest injury	4 (9.5%)	4 (11.1%)	8 (10.3%)
Abdominal injury	0 (0.0%)	1 (2.8%)	1 (1.3%)
Other fractures	4 (9.5%)	2 (5.6%)	6 (7.7%)
Comorbidities (%)				0.742
Diabetes	4 (9.5%)	3 (8.3%)	7 (9.0%)
Cardiovascular disease	5 (11.9%)	4 (11.1%)	9 (11.5%)
Respiratory disease	4 (9.5%)	2 (5.6%)	6 (7.7%)

The dual-plate group consisted of 36 patients (20 males, 16 females) aged 30–76 years (mean: 51.6 ± 11.7 years). Causes of injury included traffic accidents (n = 12), high-impact falls (n = 16), sprains (n = 4), and other causes (n = 4). Fracture types included 33C1 (n = 15), 33C2 (n = 12), and 33C3 (n = 9), with 6 open and 30 closed fractures. Associated injuries were abdominal trauma (n = 1), chest trauma (n = 4), traumatic brain injury (n = 1), and other fractures (n = 2). Nine patients had comorbidities: respiratory disease (n = 2), cardiovascular disease (n = 4), and diabetes (n = 3). No significant differences in baseline characteristics were identified between the groups (Table 1).

There were no significant differences in operative time (P = 0.743), intraoperative blood loss (P = 0.306), or follow-up duration (P = 0.749). Time to full weight-bearing (P = 0.461) and bone union (P = 0.942) were also comparable. At final follow-up, VAS scores, HSS scores, and knee flexion showed no significant differences between groups (all P > 0.05). The nail-plate group reported five complications: delayed union (n = 1), infection (n = 2), knee stiffness (n = 1), and limb shortening (n = 1). The dual-plate group reported six complications: delayed union (n = 1), nonunion (n = 1), infection (n = 1), knee stiffness (n = 1), malalignment (n = 1), and limb shortening (n = 1). Complication rates were not significantly different between groups (P > 0.05). Reoperations (e.g., implant removal or revision surgery) were performed in 10 patients in the nail-plate group and 8 in the dual-plate group, with no significant difference (P > 0.05) (Table 2).

Table 2.

Comparison of the main clinical data for two groups.

Clinical data	Nail plate group (n = 42)	Dual plate group (n = 36)	P Value
Operation time (minutes)	132.7 ± 15.1	148.8 ± 17.2	0.743*
Blood loss (ml)	315.5 ± 45.1	312.8 ± 42.5	0.306*
Average follow up period (months)	13.9 ± 4.2	14.7 ± 3.9	0.749*
Weeks to union (weeks)	15.5 ± 2.7	15.4 ± 2.8	0.942*
Weeks to full weight bear (weeks)	6.9 ± 2.4	6.4 ± 2.7	0.461*
Vas score at last follow up	1.7 ± 0.8	1.6 ± 0.6	0.166*
HSS score at last follow up	90.0 ± 3.0	91.0 ± 3.0	0.827*
Knee flexion at last follow up (°)	111.3 ± 8.2	119.9 ± 10.1	0.087*
Complications	5 (11.9%)	6 (16.6%)	0.761#
Delayed union/Nonunion	1	2	0.467#
Superficial infection	1	1	0.912#
Deep infection	1	0	0.351#
Stiffness of the knee	1	1	0.467#
Malalignment (> 5°)	0	1	0.283#
Limb shortening	1	1	0.467#
Implant failure	0	0	-
Reoperationsa	10	8	0.974&

*P-value as determined by paired-sample t-test; ^# The Fisher two-sided exact test was used for the comparison of rates.

^a such as implant removal, revision surgery, etc.; ^& The chi-square test was used for the comparison of rates.

Representative cases are shown in Figs. 1, 2, 3 and 4.

Fig. 1.

A 44-year-old female patient suffered a fracture of the distal right femur (AO/OTA 33C2) caused by a traffic accident. (A, B) Preoperative radiography. (C, D) Combined retrograde intramedullary nail and a lateral locking plate was performed for fixation and X-ray was taken at 3 days after the operation. (E, F) Radiography at 6 weeks after the operation. (G, H) Radiography at 10 weeks after the operation. (I, J) Radiography at 14 weeks after the operation. The fracture was union.

Fig. 2.

A 36-year-old female patient suffered an open fracture of the distal left femur (AO/OTA 33C2) caused by caused by a traffic accident. (A, B) X-ray at admission. (C, D) External fixation was used for temporary fixation. (E, F) Six days after the first operation, the patient received nail plate combination fixation. (G, H) Two months after the second operation, the patients suffered a deep infection. Bone cement was used to fill the bone defect after a thorough debridement and external fixation was used for fixation. (I, J) Three months later, the infection was controlled. (K, L) The bone cement was removed and autologous fibula was implanted into the bone defect. (M, N) Six months after autologous fibula implantation, the fracture was union. (O, P) Unfortunately, the patient suffered another fracture after a sprain. (Q, R) Dual plate was employed for fixation and 5 months later the bone healed finally.

Fig. 3.

A 64-year-old female patient suffered a fracture of the distal right femur (AO/OTA 33C2) caused by a fall. (A, B) Preoperative radiography. (C, D) On the third day of admission, dual plate fixation was used. (E, F) X-ray at 4 weeks after operation. (G, H) X-ray at 10 weeks after operation. (I, J) X-ray at 14 weeks after operation and the fracture healed well. (K, L) X-ray at the last follow up.

Fig. 4.

A 30-year-old male with an AO/OTA 33C1 distal right femur fracture received an operation with dual plate fixation. (A, B, C) X-ray and CT scan at admission. (D, E) X-ray at 5 days after the operation. (F, G) X-ray at 6 weeks after operation. (H, I) X-ray at 16 weeks after operation. (J, K, L) X-ray at CT scan 48 week after the operation. Diagnosis was made as nonunion of the distal femur fracture.

Discussion

Prior to the 1950s, distal femoral fractures were primarily managed nonoperatively, often resulting in poor outcomes such as joint stiffness¹⁷ deformity, and functional impairment. The 1950s and 1960s marked significant progress in surgical fracture management, initiating a trajectory of ongoing innovations in implants and techniques aimed at improving outcomes and minimizing complications. Despite these advances, the treatment of distal femoral fractures remains complex and challenging. Prognosis is influenced by multiple factors, including patient age, soft tissue condition, fracture extension into the diaphysis, articular involvement, comminution, and fragment size, all of which necessitate tailored surgical strategies¹⁸. The LISS is widely used for distal femoral fixation but is associated with relatively high rates of nonunion and varus collapse¹⁹. Retrograde intramedullary nailing offers advantages such as reduced soft tissue disruption, enhanced biological healing via canal reaming, and stimulation of the inflammatory response essential for bone regeneration. However, its nonunion rates remain comparable to those of locking plates, particularly in elderly patients with compromised bone quality²⁰. Thus, the core challenge for surgeons lies in achieving sufficient mechanical stability to support physiological loading while preserving controlled micromotion to facilitate callus formation. This balance has spurred growing interest in combined fixation techniques for distal femoral fractures in both clinical and research contexts.

Previous studies have shown that combined fixation methods are especially useful for managing comminuted fractures, medial bone defects, periprosthetic fractures, and nonunions of the distal femur^21,22. Compared to single locking plates or intramedullary nails alone, combined constructs offer superior mechanical stability, enabling earlier postoperative weight-bearing, particularly beneficial in osteoporotic patients²⁰. For instance, in a small case series involving nine patients with non-comminuted distal femur fractures, retrograde nailing combined with a lateral locking plate allowed early mobilization and achieved fracture union within an average of 20 weeks²³. A larger retrospective study of 67 cases, including native and periprosthetic fractures, demonstrated significantly higher union rates and earlier weight-bearing in patients treated with nail-plate constructs compared to single plating²⁴. Despite these advantages, combined fixation is not without limitations. In periprosthetic supracondylar fractures following total knee arthroplasty, the presence of a femoral component may preclude retrograde nail insertion. Similarly, dual plate fixation typically requires medial dissection, which increases the risk of neurovascular injury²⁵. Furthermore, anatomically contoured plates specifically designed for medial distal femur fixation are currently limited²⁶ presenting an additional technical challenge.

To date, most clinical studies on combined fixation for distal femoral fractures have been either retrospective or prospective case series, with only a few controlled comparisons evaluating dual fixation versus single plating or retrograde intramedullary nailing^13,27. This study specifically focuses on combined fixation for intra-articular distal femoral fractures classified as AO/OTA 33 C—fractures that are often highly comminuted and associated with substantial soft tissue injury. These characteristics make accurate reduction and stable fixation particularly challenging, even for experienced orthopedic surgeons. Notably, comparisons between nail–plate constructs and dual plating are scarce; only one prior report has addressed this directly²². Such a comparison is clinically relevant, as both techniques involve complex, dual-implant constructs, making them more appropriate comparators than single implant fixation. Previous research has demonstrated that neither a single LISS nor a retrograde intramedullary nail alone provides sufficient stability in comminuted 33 C fractures, particularly in osteoporotic bone, and both approaches generally fail to support early weight-bearing²⁸. Based on this rationale, our study exclusively examined nail–plate combinations and dual plate fixation, deliberately excluding single implant controls to avoid redundancy with prior research. While earlier studies have employed reconstruction plates or medial proximal tibial locking plates in conjunction with lateral plating for medial support¹⁵ we selected a proximal humeral locking plate for medial fixation. This approach enabled short-segment fixation of the medial distal femur, functioning effectively as a buttress to resist varus collapse²⁹.

As reported in the results, the mean operative time was 132.7 ± 15.1 min in the nail–plate group and 148.8 ± 17.2 min in the dual-plate group. Mean intraoperative blood loss was 315.5 ± 45.1 ml and 312.8 ± 42.5 ml, respectively. These values are notably lower than those reported in previous studies^22,30 which we attribute to the routine use of a tourniquet during surgery in our cohort. The mean time to radiographic union, knee ROM, and functional scores at final follow-up were comparable to those described by De Mauro et al.²² and Galante et al.³⁰. The overall complication rates were 11.9% in the nail–plate group and 16.6% in the dual-plate group, with 85.8% of patients across both groups experiencing no postoperative complications. Reported complications included delayed union or nonunion (3 cases, 3.8%), infection (3 cases, 3.8%), knee stiffness (2 cases, 2.6%), malalignment > 5° (1 case, 1.3%), and limb shortening (2 cases, 2.6%). These findings are consistent with previous reports by De Mauro et al.²², Galante et al.³⁰, Kregor et al.³¹ and Schütz et al.³². Further analysis revealed no significant differences between the two groups in operative time, blood loss, time to weight-bearing, or bone healing duration. At final follow-up, VAS scores, HSS scores, and knee flexion were also statistically similar. No implant failures occurred in either group. In conclusion, both combined fixation methods—nail-plate and dual-plate constructs—demonstrated comparable technical feasibility, safety profiles, and clinical outcomes. These results support the use of either technique as a viable strategy for the treatment of complex intra-articular distal femoral fractures.

This study has several limitations. First, its retrospective design may introduce selection and information biases. The relatively small sample size and short follow-up period limit the evaluation of long-term outcomes and complication rates. Additionally, the absence of a single implant control group may restrict the strength of comparative conclusions. Nonetheless, in the absence of standardized treatment guidelines, clinical judgment remains essential in managing these complex fractures. Despite these limitations, the study offers notable strengths. It is among the few to focus exclusively on AO/OTA 33 C distal femoral fractures, providing a relatively homogeneous patient cohort. While the sample size is modest, it represents one of the largest to date examining the comparative effectiveness of nail-plate constructs versus dual plating in distal femur fractures²². Although the limitations must be acknowledged, the study contributes valuable clinical insights and expands the current body of evidence.

Conclusion

For AO/OTA 33C distal femoral fractures, both retrograde intramedullary nailing combined with a lateral locking plate and dual plate fixation represent effective surgical approaches that yield satisfactory functional outcomes.

Abbreviations

CPM

Continuous passive motion

HSS

Hospital For Special Surgery

LISS

Less Invasive Stabilization System

ROM

Range of Motion

VAS

Visual Analogue Scale

Author contributions

Conflict of InterestThe authors declare that there were no commercial or financial relationships that could be considered potential conflicts of interest at the time the research was conducted.Informed ConsentWritten Informed consent was obtained from all patients. JW and WX wrote the manuscript, analysed and interpreted the patient data. HL and JZ was responsible for acquisition of data, and analysed and interpreted the patient data. YX and WL were responsible for designing the study, and the analysis and interpretation of the data. All authors have read and approved the final manuscript.

Data availability

The datasets generated and/or analysed during the current study are not publicly available due [Some patients are unwilling to disclose their information publicly] but are available from the corresponding author on reasonable request.

Competing interests

The authors declare no competing interests.

Informed consent

Written informed consent was obtained from all participants.

Ethics approval

This study was approved by the Ethics Committee of the School of Medicine, Xiamen University (Approval No. 2023 − 1257).