Outcomes of Distal Femur Non-Union Following Lateral Locked Plating Treated withan Addition of A Medial Locking Plate and Autogenous Bone Graft

activity functional status. Addition of medial locking plate and autogenous bone grafting adds biomechanical stability, prevents varus collapse and implant failure, and decreases the morbidity associated with non-union. We evaluated results of addition of medial locking plate and bone grafting in aseptic distal femur non-union with stable lateral implant. Methods: Between 2009 and 2019, we retrospectively reviewed 14 cases of clinically and radiologically established aseptic distal femur non-union treated by single stage procedure involving addition of medial locking plate and autogenous bone grafting. The fractures were classified according to the AO classification system was used for distal femur fractures. Patients were regularly followed-up for a minimum period of 12 months for clinico-radiological signs of union, functional outcome and any complications associated with it. Conclusion: Timely medial locking plate augmentation and bone grafting done is an effective procedure to achieve union and prevent failure of the already present lateral implant in distal femur nonunion


390
poor quality of life, plate bending, plate fracture, plate pull-off and locking screw failure. Fractures treated with lateral locking plates that fail to heal usually maintain alignment and generate less callus, suggesting that callus inhibition because of overly rigid fixation rather than hardware failure is the primary problem .
We believe the augmentative medial plating and autogenous bone grafting done for healing problems associated with stable locked lateral distal femur plating provides greater stability leading to a successful union and prevent failure of the primary lateral implant. However, to the best of our knowledge, there is less literature available on non-union of distal femur treated with locking medial plate and autogenous bone grafting. We, therefore, sought to determine [1]the preliminary results of the non-union of the distal femur with an in situ stable locking lateral plate after treatment with the addition of a locking medial plate and autogenous bone grafting, and [2] any complications associated with the treatment.

Materials And Methods
A retrospective clinical evaluation of non-unions of distal femur fractures with an in situ stable lateral locking plate, treated by medial plate augmentation and autogenous bone grafting at was performed in our institute, a National Board of Examinations, India accredited teaching institute. We identified from the hospital data, that between 2009 and 2019, 14 patients of distal femur non-union following locked lateral plating of distal femur identified were treated by augmentative locking medial plate and autogenous bone grafting at a mean of 7.2 months after the primary surgery (range 5 months to 14 months). This study was approved by our institutional review board.In our institution, distal femoral fractures treated by locked lateral plating, not showing expected radiological and clinical signs after three months are kept non-weight bearing and strictly followed for next consecutive three months, for clinical and radiographic signs of progression to healing. Patients with persistent limp, pain and showing no clinical or radiographic signs of progression to healing on plain radiographs or CT (computed tomography) scan, the fracture is considered to be non-united.

Statistical Data Analysis
Descriptive analysis was carried out by the mean and standard deviation for quantitative variables, N and proportion for categorical variables. All Quantitative variables were checked for a normal distribution within each category of an explanatory variable by using visual inspection of histograms and normality Q-Q plots.
Shapiro-wilk test was also conducted to assess normal distribution.    can be further decreased by using more flexible titanium plates, as titanium implants are normally twice as flexible as similar-sized stainless steel implants [16]. The use of titanium versus stainless steel plates has been reported to correlate with varying degrees of union rates in various series [11,17,18]. Rodriguez et al, tried to identify construct characteristics like screw density, plate design and material as predictors of non-union after locked lateral plating of the distal femur and found combined plate design and material to have a significant influence on the risk of non-unionLinn, et al [18].
suggested dynamic locked plating to increase the axial motion in metaphyseal bridge plating of distal femur fractures. Dynamic plating was achieved using an over drilling of the near cortex while inserting the proximal screws. They concluded that dynamic plating seems to allow better callus formation without fixation failure [19].
Poly-axial screw plate designs were used in an attempt to improve peri-articular control by the placement of locking screws in a range of insertion angles [20,21]. But the high rate of early mechanical failure with the variable angle distal femoral locking compared to traditional locking plates has been reported and the authors cautioned practising surgeons against the use of this plate for metaphyseal fragmented distal femur fractures [22].
Distal femoral non-unions following locked lateral plating can cause persistent pain, limp, loss of ambulatory function, and decreased range of motion at the knee [23,24].In the presence of these alarming signals, the surgeon should suspect healing problems. The radiographs of the previous three months need to be compared to assess the progress of the union, loss of reduction, change of alignment.Out of 14 patients in our series, 12 fractures were primarily fixed with stainless steel lateral locked plates and two with titanium plates. Because of the low cost, stainless steel implants are commonly used in our part of the world and the decreased flexibility of these implants as pointed by different authors [11][12][13][14][15][16][17][18], may have contributed to the impaired healing seen in these patients.Open fractures are often associated with significant stripping of periosteum, damage to bone and soft tissues, and disruption of vascularity [25]. The open nature of the injury has been shown to contribute to the development of nonunion of distal femoral fractures [24]. In our series, there were 9 compound fractures and five patients had Grade III compound injuries. The compound nature of the fracture was a probable factor in the development of non-union in these cases. Out of 9 compound cases, 6 six cases were closed with primary suturing, and three cases required split-thickness skin graft during initial surgery.
One patient (Figure 2) had an ipsilateral compound fracture of the proximal tibia which required gastrocnemius flap for coverage.
All patients with a range of motion less than 90 degrees [2][3][4][5][6][7][8][9][10][11][12][13] were stiff probably due to the compound nature of the fractures and this stiffness may have contributed to increased stress on the implant during joint mobilization ( Table 2). In two cases [3,8] in (table 2)  Several studies have shown that dual plating in distal femoral fractures provides increased stability by decreasing the lever arm that acts on the femoral axis and thereby decrease the load applied on the fracture [28][29][30]. In one latest study in which unstable distal femoral fractures created in artificial femora simulating osteoporotic bone were fixed with locked lateral plating or double plating were subjected to axial, torsional and quasi-static loading.
Double plating revealed significantly smaller longitudinal and shear displacement than single lateral locked plating [31].In our series, medial plate augmentation helped to eradicate the motion at the fractures site order to eradicate which was visible before the addition of medial plate. The addition of autogenous corticocancellous bone graft from the iliac crest improved the biological environment to enhance the healing.In our series, proximal humeral locked plates were used for medial plate augmentation in 5 cases and medial distal tibia locking plates were used in 3 cases, and lateral distal femoral locking plate was applied to medial side in 4 cases, proximal tibia 'L' locking plate in one case and Low Contact  (Table 3). The choice of the implant was made according to the contour of the bone. Number of distal locking holes in these plates, provide more options to the surgeon while inserting the distal screws. It may not be possible to use all holes of the plate due to long screws used during locked lateral plating, which may interfere with the insertion of medial screws. No attempt was made to flush these plates with the bone to allow the bone graft to be packed between the bone and the plate. The bone graft was obtained from the posterior iliac crest.
We used medial locking plates with more distal locking options, to prevent interference with long screws incorporated in the lateral locked plate.Union was achieved in all patients within 7 months, and all patients were able to put full weight on the affected lower limb once united. Range of movements of knee improved in some patients, and all patients had some pain relief.The limitations of the study are its retrospective nature, inconsistent clinical records of two patients who were not primarily treated at our hospital, a small number of patients to draw any statistically significant conclusions (Table 4). All patients treated from 2009 to 2018 could be traced and none of the patients was lost to follow up, which is the strength of our study.

Conclusions
Non-union of distal femoral fractures locked lateral plating have a significant influence on the quality of life of the patient.
When impaired healing is evident clinico-radiologically after locked lateral plating of distal femoral fractures and the plate is stable, timely medial plating and autogenous bone grafting prevents the implant failure and leads to a successful union.

Conflicts of Interest:
The authors report no conflicts of interest.

Declarations of interest: None.
Source of Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-forprofit sectors.