Distal femur fractures are those involving the distal 15cm of the femur1 accounting for 1% of all fractures and about 4-6% of femur fractures reported. The incidence of distal femur fracture is reported to be 4-9%/100,000 in the population worldwide. According to AO classification, these fractures are classified according to their location and pattern into three types;extraarticular (Type A), partial articular (Type B)and completely articular (Type C) ones. The goals of treatment of AO Type C distal femur fracture are articular surface restoration, maintaining the length of the medial and lateral columnand anatomical alignment. The complexities of distal femur fracture management are accentuated in cases with medial comminution, bone lossand open injury. Surgical management of Type C distal femur fractures varies from a single column,bicolumn plating and supracondylar nailing depending on severity of comminution and column involvement. The fixation modalities of distal femur fractures with medial comminution and bone loss require restoration of the medial column, traditionally achieved by bicolumn plating of the distal femur. The addition of a medial column plate involves devascularization of bony fragments, risk of iatrogenic vascular injury, extended surgical time and longer learning curve. The novel addition of TENS for the medial column along with DFLCP is a comparatively minimal invasive technique that prevents varus angulation achieves medial column stabilization, and early fracture union.

This is a prospective randomised interventional comparative study on 30 patients admitted to the Institute of Orthopedics and Traumatology, Madras Medical College, Rajiv Gandhi Government General Hospital, Chennai from March 2023 to March 2024. It includes patients with distal femur fracture of AO type C who were admitted to our institute. Patients satisfying the inclusion criteria and consenting for the study were included. These patients with AO type C distal femur fracture are divided into Group A (15 cases) and Group B (15 cases) with a simple randomization sampling method. Patients with open injury underwent wound debridement and external fixator application on the day of admission and definitive fixation was done later as permitted by patient’s wound status. Preoperative plain radiographs and CT evaluations with 3D reconstruction were done to assess fracture extent, comminution, and bone loss. Group A patients were subjected to open reduction internal fixation with Distal femur locking compression plating (DFLCP). Group B were managed with DFLCP and minimally invasive percutaneous Titanium Elastic Nailing system introduced medially in 7 patients and laterally in 8 patients. Suture removal was done on the 12th postoperative day. All Patients were followed up at 6th week and every month for one year thereafter. Functional outcomes were assessed using the Schatzker and Lambert scoring system and radiological measures at the end of 1-year follow-up. Significant varus angulation was accounted as more than 5 degrees on the postoperative radiographs. Inclusion criteria: • AO type C (intra-articular fracture) • Patients above the age group of 18 • Grade I, Grade II, and Grade IIIA, IIIB of Gustilo Anderson classification of open fracture. Exclusion criteria: •Grade IIIC injury •Pathological fracture •Patient with associated neurovascular injury •Age group of <18 •Patients with ipsilateral lower limb fractures. Surgical technique: The standard procedure in both Group A and Group B was open reduction internal fixation with DFLCP through standard distal femur lateral approach2.The patients were placed supine on a radiolucent table and an incision was made in the lateral aspect of the thigh. The vastus lateralis muscle detached from the lateral intermuscular septum and retracted medially after lateral para-patellar arthrotomy was made. Articular congruity is restored and stabilizedtemporarily with k-wires. Lateral column length maintained and fixed with appropriate holed DFLCP as deemed necessary. In Group B patients, the medial column restoration was done using a single TENS of size 3-4 mm based on distal femur geometry. The TENS was prebent as necessitated by the column alignment and introduced percutaneously into the medullary canal under C-arm guidance. Medial entry of TENS was done in 7 patients and lateral entry was done in 8 patients. The wound was then closed in layers and Sterile dressing was done. Postoperatively the patients were started on quadriceps strengthening exercises on day 1, knee and ankle mobilization exercises from day 2. Suture removal was done at the 12th POD. All Patients were followed up at 6th week and every month for one year thereafter. Patients were started on partial weight bearing based oncallus formation on standard radiography and proceeded to full weight bearing on complete radiological and clinical union. Patients were analysed using the Schatzker and Lambert scoring system and radiological measures for union status at every follow up visit and varus angulation was measured at the final followup. Statistical analysis: The recorded data were presented as mean, standard deviation, frequency, and percentages. Continuable variables were compared using the independent sample t-test. Categorical variables were compared using the Pearson chi-square test. Significance was defined by P values less than 0.05 using a two-tailed test. Data analysis was performed using IBM-SPSS version 25.0 (IBM-SPSS Science Inc., Chicago, IL).

Amongst the study population of 30 patients, 15 were treated with DFLCP alone (Group A), and 15 were treated with DFLCP and TENS (Group B) based on simple random sampling and were followed up for a period of 1 year. Our study included 11 patients with open injury of which five were in Group A and six were in Group B. The average age group of our patients was in the range of 30-49 years (50%) with a male preponderance of about 83%. In our study, Group A patients started partial weight bearing <9 weeks in 53% of patients, and Group B began partial weight bearing <9 weeks in 93%. The average time for partial weight bearing was 9.93 ± 1.71 weeks in Group A and 7.73 ± 1.33 weeks in Group B. There was a statistically significant difference between both groups in the average time for partial weight bearing with a p-value of 0.001. Figure 1:Comparison of the average time for partial weight bearing between both groups Eighty percent of patients in Group B achieved complete union by 16 weeks whereas in Group A, only 47% achieved complete union by 16 weeks. The average time to complete union was 17.14 ±2.07 weeks and 15.33 ± 1.72 weeks in Group A and Group B respectively. There was a statistically significant difference between both groups with a p-value of 0.016. Figure 2:Comparison of average time to complete union between both groups According to the Schatzker and Lambert scoring system, the results were excellent to good outcomes in 7(46.7%) patients in Group A and excellent to good outcomes in 12(80%) patients in Group B, fair in 5(33.3%) patients in Group A and fair in 2(13.3%) patients in Group B, poor in 3(20%) patients in Group A and poor in 1(6.7%) patient in Group B. Schatzker and Lambert scoring system showed no statistical significance (p-value = 0.165) between both groups. Figure 3:Comparison of Schatzker and Lambert scoring system between both groups At the final follow-up, varus angulation of more than 5 degrees was observed in Five (33%) patients in Group A, whereas no varus angulation was observed in Group B. There was a statistically significant difference between both groups in varus angulation with a p-value of 0.014. Figure 4:Comparison of varus angulation between both groups Complications observed in both the cohorts were infection, non-union, varus collapseand implant failure as shown in Figure 5. Three patients in Group A and two in Group B reported post-operative infections Figure 5: Comparison of complications between both groups Figure 6:A case of 40/M Grade IIIB open distal femur fracture, AO type C2 with medial comminution and bone loss (a) Pre-op; (b) immediate post-op; (c) 6-month post-op; (d) 1-year post-op Figure 7: A case of 28/F, Post distal femur lateral compression plating implant failure status, AO type C fracture (a) Pre-op; (b) immediate post-op; (c) 6 months post-op; (d) 1-year post-op

AO classifies distal femur fractures based on their location and pattern into three types Extraarticular (Type A), partial articular (Type B) and completely articular (Type C). Our study included Type C distal femur fracture with medial comminution, bone loss and open injuries. The restoration of the medial and lateral columns along with articular surface reduction is pre requisitefor all distal femural fractures. The restoration of the medial column is achieved by medial column plating, an invasive procedure leading to the devascularisation of the medial column and risk to vascular structures. The addition of minimally invasive TENS for medial column support in comminuted distal femur fracture along with DFLCP prevents varus angulation, achieves early fracture healing and restores knee function. This prospective comparative study was conducted on 30 patients, 15 patients were treated with DFLCP (Group A), and 15 patients were treated with DFLCP with TENS (Group B) based on simple random sampling method. Our study included 11 patients with open fractures, five in Group A and Six in Group B. MongkonLuechoowong et al3 (2008) reported in their study that the mean age was 39 years with 66 males (82.5%) and 14 females (17.5%) which is comparable to our study, with a mean age of 45 years and male preponderance of 83%. Weight M et al4 (2004) reported in their study that road traffic accidents accounted for (82%) of patients with distal femur fractures which is the same as reported in our study (80%). Pramod G et al5 (2016) reported in their study, that the majority of patients with distal femur fractures belonging to AO type C fractures was 55% which is marginally less than that reported in our study (63%). Anil Gupta et al6 (2019) in their landmark study on the management of distal femur fracture, using TENS for a medial femoral defect along with lateral column plating decreases the incidence of postoperative varus angulation. They achieved union at less than 16 weeks in 68% of patients, whereas we achieved 80% by 16 weeks in Group B. The Schatzker and Lambert scoring system is excellent to good outcomes in 72% of patients which is similar to 80% in Group B. In a similar study, Anchul Kumar7 et al (2021) reported the use of TENS for medial femoral defect along with a distal femur locking compression plate and stated that it eliminates the need for a medial side plate. They achieved a union in 78% of patients by 15-20 weeks in the TENS group whereas we achieved union in 80% of patients by 15-20 weeks in Group B. The Schatzker and Lambert scoring system is excellent to good in 74% of patients which is similar to 80% in Group B. Erdal Eren et al8 (2023) in their biomechanical study on lamb cadaveric femur, reported increased bending strength and stability with the application of TENS along with bridging plate in femur fractures. This is validated by the clinical outcome of our study. Davison et al9 (2003) reported complications of varus angulation of greater than 5 degrees in 40% of patients treated with lateral column plating alone which similar to our findings with varus angulation of 33% of patients managed with DFLCP alone. J.Dheenadhayalan et al10 (2021) reported in their study, that the use of allograft for distal femur medial condyle bone defect achieved a primary complete union in 68% of patients and the rest of them needed additional procedures for the union. In our study, we used TENS to support the medial column and achieved the complete union of all patients without secondary intervention. However, the use of allograft is associated with complications as has been reported in the above quoted study. Ricci et al11 (2012) in their study, encompassing a total of 335 patients with lateral column plating alone reported an incidence of non-union and implant failure is 19% which was in accordance to the results in our study with the DFLCP group of about 13% cases. The measurement of varus angulation as criteria for postop follow-up, restoration of periarticular anatomy, and column length, done in our patients with DFLCP and TENS has not yet been documented in studies on similar subjects published till date. Our study also includes patients with open fractures managed with DFLCP and TENS and outcomes measured. This analysis of patients with open fractures of the distal femur managed as described above is also a first among studies published to the best of our knowledge. In our study, three patients (27%) in Group A and two patients (13%) in Group B had postoperative infections and were managed with wound debridement with intraoperative culture and appropriate antibiotics. A subgroup analysis of Group B patients showed, that 8 (53%) with a lateral entry of TENS with DFLCP which shows significantly decreased varus angulation compared to medial entry of TENS. This preliminary observation however requires further validation. Hence, in Group B patients the medial column support with TENS, results in early callus formation, weight-bearing and better functional outcomes.

The results of our study prove that in Comminuted intraarticular Type C fractures, excellent results are obtained with the addition of TENS with DFLCP. This ultimately avoids the additional procedure of medial column plating and the morbidity associated with it. This novel addition of minimally invasive TENS with the DFLCP procedure overcomes the long-term complications of varus angulation, non-union, and implant failure in distal femur fractures. Clinical significance: The comminuted intra-articular fractures of the distal femur with medial comminution involvement need medial column stabilization in addition to lateral column plating. This stabilization is usually achieved by adding medial column plating, which can be overcome by minimally invasive TENS procedures with excellent results. Limitation: Our study was a single-centrestudy and the sample size was small. An increased sample size and longer follow-up are needed for further validation of our results.

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