Abstract
Purpose
The treatment of distal femur fractures with extensive metaphyseal comminution is frequently complicated by high rates of nonunion and varus collapse. Dual plating with lateral and medial locking plates for these types of fractures has shown promising results in the recent literature. We hypothesize that dual plating of comminuted distal femur fractures leads to higher union rates and lower revision rates compared to an isolated lateral locking plate.
Methods
A retrospective medical chart review between January 2015 and December 2017 was conducted. Inclusion criteria included patients 18 years of age and older who sustained a complex distal femur fracture (AO/OTA 33-C2/33-C3 or periprosthetic fracture with significant metaphyseal comminution) and at least 6 months of follow up. Patients with simple fracture patterns, alternative fixation methods, and inadequate follow up were excluded. All patients in the single plating group were treated with a lateral distal femoral locking plate using a lateral approach. In the patients treated with dual plating, an extensile parapatellar approach was utilized for fracture reduction and placement of an adjunctive medial plate. Demographic information, fracture types, injury severity score (ISS), medical comorbidities, type of surgical fixation, union rates, complications, knee range of motion, time to follow up, and need for revision surgery were extrapolated from the medical charts for analysis.
Results
Twenty-one patients were included in the study. Thirteen patients underwent single plate fixation and 8 underwent dual plate fixation. There were no significant differences in demographics, number of co-morbidities, fracture classification, or ISS between single and dual plate groups (p > 0.05 for all). There was a statistically significant difference in union rates between the single plate group (6 nonunions, 4 unions, and 3 delayed unions) and the dual plate group, with no nonunions or delayed unions (p = 0.0049). Although not statistically significant, 4 patients treated with single plating underwent revision ORIF, compared to none in the dual plating group (p = 0.13). There were no significant differences in time to follow up, time to full weight bearing, or infection rates (p > 0.1 for all).
Conclusion
Based on these results, the medial and lateral locked plating technique demonstrates a higher union rate, with possible lower rates of revision surgery, compared to a single lateral plate in highly comminuted distal femur fractures.
Level of evidence
Level 3. Retrospective Cohort Study.
Keywords: Distal femur, Dual plating, Locking plate, Union, Nonunion
1. Introduction
The treatment of distal femur fractures with extensive metaphyseal comminution is particularly difficult. The accepted standard of fracture fixation for these injuries includes open reduction internal fixation (ORIF) using a lateral distal femoral locking plate or intramedullary nailing (IMN), usually dependent on the fracture location, articular involvement, and bone stock.1,2 Despite advances in locking plate technology and implant design, nonunion rates are still reported up to be as high as 18–20% using single distal femoral locking plates.2,3 Ebraheim et al.3 performed a meta-analysis of 19 studies published over 12 years on the outcomes of distal femur fractures and found that the most common risk factors for nonunion were metaphyseal comminution, fractures treated with ORIF, and open fractures.
Many previous studies have shown that ORIF of distal femur fractures with extensive metaphysical comminution, either AO/OTA 33-C2 or 33-C3, is complicated by high rates of varus collapse with medial comminution, loss of fixation, and nonunion.2, 3, 4, 5 The technique of dual plating with lateral and medial locking plates for these fractures has recently been introduced into the orthopedic literature with promising results.6, 7, 8, 9 Our institution has adopted the dual plating method, utilizing a lateral and anteromedial locking plate, for distal femur fractures with extensive metaphyseal comminution and articular involvement. To our knowledge, there have been no studies directly comparing outcomes with single versus dual plate fixation in AO/OTA 33-C2 or 33-C3 distal femur fractures. The primary aim of this study was to assess the outcomes of single compared to dual plating techniques with regard to nonunion, all cause revision rate, and infection. Secondarily, we assessed knee range of motion and time to full weight-bearing.
2. Methods
A retrospective review of medical charts querying CPT codes 27511, 27514, or 27513 at a single level one trauma center was conducted for patients 18 years of age and older, who sustained a distal femur fracture between January 2015 and December 2017. These fractures were treated by one of three fellowship trained orthopedic traumatologists. Only fractures with significant metaphyseal comminution were included in the study. Using radiographic analysis, fractures were classified using the OTA-AO classification as 33-C2 or 33-C3. Periprosthetic fractures with metaphyseal comminution above a total knee arthroplasty were also included. Simple fracture patterns were excluded. A minimum of 6 months of post-operative follow up was needed to be included in the study. Fractures treated without plate fixation, such as intramedullary nailing or distal femoral replacement, were excluded from the study.
Patients were placed into two groups based on use of single or dual plate fixation. All patients in the single plating group were treated with a lateral distal femoral locking plate utilizing a standard lateral approach to the distal femur. In the patients treated with dual plating, an extensile parapatellar approach was utilized for reduction and fixation of the fractures. A precontoured distal femoral locking plate was placed along the lateral distal femur, followed by placement of a straight locking plate contoured to the anteromedial surface of the distal femur.
Fracture union was determined by surgeon documentation of painless weight bearing, combined with radiographic analysis of at least 3 healed cortices and/or callus formation. Fracture nonunion was determined by progressive radiographs without evidence of bony healing after 6 months follow-up, confirmatory CT scans, as well as the need for future revision nonunion surgery. Delayed union was determined by the surgeon documentation in the medical record after 6 months of follow-up. The medical record was interrogated to ascertain the incidence of revision ORIF in each group, as well as the incidence of return trips to the operating room for other reasons, e.g. stiffness or painful hardware. Demographic information, injury severity score, medical comorbidities, smoking status, type of surgical fixation, complications, and knee range of motion were also extrapolated from the medical charts for review.
Continuous variables were assessed for normality and evaluated using a t-test or, for non-parametric data, a Wilcoxon Rank Sum test. Categorical variables were evaluated for frequency (n, percentage) and tests of comparison were performed using either chi square or Fisher's Exact test. SAS Enterprise Guide 7.11 HF3 (SAS Institute, Inc, Cary, NC) was used to conduct the statistical analysis.
3. Results
A total of 101 patients were queried, 21 patients met the inclusion criteria for the study. Of the 80 patients who were excluded, 32 underwent intramedullary fixation, 17 had simple fracture patterns, 11 underwent distal femoral replacement, 7 were coding errors, 9 patients (7 of which were single plated) had inadequate follow up, 3 underwent alternative fixation methods, and 1 patient who died prior to assessment of union. Of the patients who met inclusion criteria, the mean age of patients was 61 years and 19 (90%) were female. Seven fractures were classified AO/OTA 33-C2, 7 fractures were AO/OTA 33-C3, and 7 fractures were periprosthetic. There were 13 patients who underwent a single plate fixation and 8 who underwent dual plating. There were no differences in the single and dual plating groups when comparing age, fracture type, the rate of open fractures, the median injury severity score (ISS), tobacco use, diabetes, and BMI (p > 0.05 for all, Table 1).
Table 1.
Demographic characteristics between plating groups.
| Single Plate (n = 13) | Dual Plate (n = 8) | p-value | |
|---|---|---|---|
| Age, years | 54, (46–76) | 66.5 (55–78) | 0.27 |
| Fracture Classification (%) | 0.90 | ||
| 33-C2 | 4 (30.8) | 3 (37.5) | |
| 33-C3 | 5 (38.4) | 2 (25) | |
| Periprosthetic | 4 (30.8) | 3 (37.5) | |
| Open Fracture (%) | 4 (30.8) | 1 (12.5) | 0.61 |
| ISS | 9 (9–10) | 9 (9–11.5) | 0.60 |
| Tobacco (%) | 5 (38.4) | 3 (37.5) | 0.90 |
| Diabetes (%) | 2 (15.4) | 2 (25) | 0.62 |
| BMI kg/m2 | 27.0 (24–30) | 29.5 (28.5–32) | 0.22 |
Patients were followed for an average (range) of 12 (6–29) months. There was no difference in the time to follow up between the single plating group (median (interquartile range): 8(6–15) months) and dual plating group (13 (11–22) months) (p = 0.14). When assessing the union rate by type of plate used, there were no non-unions or delayed unions in the dual plating group compared to 6/13 non-unions and 3/13 delayed unions in the single plating group (p = 0.0049, Table 2). An example of a non-union with hardware failure in the single plating group is demonstrated in Fig. 1.
Table 2.
Outcomes of single and dual plate cohorts.
| Single Plate | Dual Plate | p-value | |
|---|---|---|---|
| Union Type (%) | 0.0049 | ||
| Non-union | 6 (46.2) | 0 (0) | |
| Union | 4 (30.8) | 8 (100) | |
| Delayed union | 3 (23) | 0 (0) | |
| Infection (%) | 1 (100) | 0 (0) | 0.90 |
| Time to Union, weeks | 12.5 (8.0–20.0) | 7 (6.25–7.0) | 0.0012 |
| Time to Full Weight Bearing, weeks | 8.0 (8.0–12.5) | 7.90 (6.25–10.0) | 0.32 |
| Knee ROM | 100 (92.5–115) | 90 (70.0–90.0) | 0.036 |
| Return to OR (%) | 4 (30.8) | 2 (25) | 0.90 |
| Revision ORIF | 4 (30.8) | 0 (0) | 0.13 |
Fig. 1.
Demonstration of distal femoral nonunion with single plate fixation, with varus collapse and hardware failure, at 4 months post-operative follow up.
The time to union was significantly different between the two groups, averaging 7 weeks (6.25–7.0) weeks) in the dual plating group, and 12.5 weeks (8.0–20.0) weeks) in the single plating group (p = 0.0012, Table 2).
There was no statistically significant difference in patients undergoing revision ORIF between the dual (0/8) and single (4/13) plating groups (p = 0.13, Table 2). Two single plating patients with nonunions did not require any future surgery at 13 and 22 months from their index procedure due to the lack of clinical symptoms. The 3 single plating patients with delayed unions required bone stimulation and eventually healed.
Sixteen patients, 8 patients per group, had follow up knee range of motion data available for analysis. There was a significant difference in knee range of motion between the dual (90.0 (70.0–90.0)°) and the single (100 (92.5–115)°) plating groups (p = 0.036, Table 2). Two patients in the dual plating group developed significant knee stiffness, one requiring arthroscopic lysis of adhesions and the other requiring knee manipulation under anesthesia. Two patients in the dual plating group developed mild anterolateral heterotopic ossification, neither requiring any further surgical intervention at 12 and 13 months. There was no significant difference in the time to weight bearing between the single (8.0 (8.0–12.5) weeks) and the dual (7.90 (6.25–10.0)weeks) plating groups (p = 0.32). Additionally, one infection was reported in the single plating cohort leading to a septic nonunion (Table 2).
4. Discussion
Our results demonstrate that all comminuted distal femur fractures treated with dual locking plate fixation proceeded to clinical and radiographic fracture union. Radiographs shown in Fig. 2 demonstrate an example of the dual plating technique, with progression to fracture union.
Fig. 2.
a) Preoperative radiographs demonstrating a comminuted OTA-AO 33 C-2 distal femur fracture. b) Intraoperative fluoroscopy radiographs demonstrating fracture reduction and fixation. c) Final radiographs at 10 month follow up visit demonstrating uncomplicated fracture union with dual plate fixation.
Conversely, there was a 46% nonunion rate in the single plate cohort. The time to union was 7 weeks for the dual plating group and 12.5 weeks for the single plating group. The difference between the two groups in this study was found to be statistically significant, and these satisfactory results with dual plating are comparable to prior studies on this technique.
Steinberg et al.9 studied 32 patients treated with the double plating technique for distal femur acute fractures, nonunions, and periprosthetic fractures. They demonstrated union in 30 patients, with one nonunion and one refracture.
Imam et al.6 studied 16 patients with comminuted distal femur fractures treated with dual plate fixation. They showed no loss of reduction in any case, average time to union of 6 months, with a good-to-excellent outcome in 68% of patients. Metwaly and Zekaria7 studied a larger cohort of 23 patients with similar fractures treated with single-incision double plating of these fractures. They demonstrated a 82.6% union rate with average time to union of 9 months.
Zhang et al.8 and Khalil and Ayoub10 also presented similar studies with good-to-excellent results in the majority of cases, however different approaches were introduced.
None of the above listed studies on this topic have directly compared single and dual plate fixation of these comminuted distal femur fractures. To our knowledge, the current study is the first to compare the two.
Despite not demonstrating a statistically significant difference, of note was that the single plate cohort had more patients return to the operating room for revision fixation. This trended towards statistical significance.We hypothesize that this finding is clinically relevant and that perhaps with a larger population, there may be a significant association with revision surgery. It does appear that the nonunion rate with single plating in the current study is slightly higher than previous literature.3,11 This could be attributed to selection of only those fractures with significant comminution.
The use of dual plating in other long bone fractures, such as distal humerus fractures, has become widely adopted due to increased strength and bicolumnar support.12, 13, 14 Briffa et al.15 has demonstrated biomechanical superiority of dual plating of distal femur fractures compared to single plating in a controlled Sawbones model.
There was a difference in knee range of motion at final follow up in the current study, with the dual plating group averaging 90° compared to 100° in the single plate cohort. It is difficult to conclude if these values are clinically relevant as the difference appears small, and most values recorded were an estimate obtained by the clinician during follow up visits, usually without precise goniometer measurements. Two patients from the dual plate cohort, however, did return to the operating room for this problem. One underwent manipulation and the other underwent arthroscopic lysis of adhesions. An increased risk for knee stiffness has been shown in prior studies as well, although a more extensile approach was utilized.10 We do believe it is imperative to encourage early range of motion in these patients to prevent this potential complication. Other complications were similar between the two cohorts. Overall, dual locking plate fixation of these fractures does appear to be a safe and effective technique, and possibly provides an improved environment for fracture healing compared to single plate fixation when extensive comminution is present.
The advantages to this study include two well-randomized cohorts without significant differences in confounding factors as previously listed. We were able to select patients with a specific fracture type, which provides some control to the degree of injury. Also, all three of our traumatologists are fellowship trained and practice basic AO principles of fracture fixation at our level 1 trauma hospital. Our hospital system and insurance provider are allied, which possibility decreases that chance that future treatments are sought outside of the system.
There are several limitations to this retrospective study. Our final sample size was modest after considering exclusion criteria and loss to follow-up, potentially due to uneventful union or seeking follow-up healthcare elsewhere. Additionally, patients with uneventful post-operative courses are generally discharged from the practice thus making it prohibitive to obtain long periods of follow-up. Another difficulty with the study is assessing union, which has been shown controversy in prior literature. We used clinical analysis as well as expert interpretation of radiographs, which are commonly used criteria used for assessing union in the literature.16,17 Finally, there was a lack of standardization in measuring knee range of motion at follow up visits.
Careful soft tissue handling is paramount with this technique. It is important to avoid excess soft tissue stripping when reducing and stabilizing fractures. With regards to construct strength and stiffness, it is important to maintain a good working length to optimize strain at the fracture site. We do believe further biomechanical studies are important to help assess the most optimal construct configuration with this technique.
5. Conclusion
Our findings support dual plating of comminuted distal femur fractures as an effective technique with higher rates of union and possibly lower revision rates compared to single plate fixation. Further biomechanical studies, prospective clinical trials, and cost analyses need to be performed to further investigate the significance and reliability of this method.
Conflicts of interest
The authors declare that there are no conflicts of interest.
Footnotes
Supplementary data to this article can be found online at https://doi.org/10.1016/j.jor.2019.09.022.
Appendix A. Supplementary data
The following is the Supplementary data to this article:
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