Comparison of locking compression plating vs retrograde intramedullary nailing in distal femur extra-articular fractures

INTRODUCTION

The fractures of distal femur with an incidence of 10 per 100000, account for 4-7% of all femoral fractures.¹ It has a bimodal distribution of incidence with age: incidence is highest in women more than 70 years and in adolescent boys and men 15 to 25 years old.² About 85% are fragility fractures sustained by the elderly due to fall from standing height and the rest are typically sustained by polytrauma patients.^1-3 Most fractures are extra-articular and significantly comminuted.⁴

The two surgical techniques which are commonly used are extramedullary fixation with an anatomical locking compression plate (LCP) or intramedullary fixation with a retrograde nail (IMN).⁴ LCP offers anatomical fixation and has been used since long for fixation of these fractures. But open reduction hampers the natural process of fracture healing and is associated with high rates of infection and non-union.⁵ Retrograde IMN has a mechanical advantage of an intramedullary device that is close to the axis of the femur and has the biological advantage of minimal disruption of blood supply and also stimulation of blood supply aided by reaming.⁶

The aim of the study was to compare the outcome of distal femur fracture treated with LCP against those treated with Retrograde IMN in terms of clinical, functional and radiological outcomes.

METHODS

A prospective study conducted at a tertiary care hospital from July 2016 to December 2019. All patients coming/referred to the hospital with distal femur extraarticular fracture who met with the inclusion criteria were informed about the study and those who gave consent to be a part of the study were included.

Inclusion criteria

Patients who had I) Acute unilateral extra-articular distal femur fracture (AO type A1, A2, A3), and II) Gustilo-Anderson type 1 open fractures were included in the study.

Exclusion criteria

Patients who had I) Gustilo type 2 and 3, II) Pre-existing femoral deformity, III) Pathological fracture, IV) Old fractures (>3 weeks old) V) Patients requiring ICU care or transfer to other dept for treatment, VI) Associated neurovascular injury and VII) Periprosthetic fracture were excluded from study.

For every patient meeting the inclusion criteria, on admission, a detailed history was taken, related to age, sex, occupation, mode of injury, and associated medical illness. Anteroposterior and lateral roentgenographic views of knee and femur were taken. Patients were kept on skin traction over Bohler-Braun splint till they were operated. Patients were subjected to all routine investigations and were taken up for surgery as soon as he/she was fit for anesthesia. Patients were randomized into 2 groups using the random table generated using Microsoft excel. Group 1 patients were treated with distal femur LCP (Figure 1 and 2) and group 2 patients were treated with IMN (Figure 3 and 4).

Both the groups were operated by the same set of surgeons who had minimum 5 years of experience post-MS in Orthopedics from recognized colleges in India.

Operative timing and intraoperative blood loss were recorded for comparison in the study. Post-operatively, patients were kept under observation for 3 days. One wound check was done on second-day post-op. Patients were taught active knee ROM exercises and assisted walking following which patients were discharged on the third day. Suture removal was done on twelfth-day post-op. Patient were advised partial weight bearing at 3 weeks and encouraged to do full weight bearing at 6 wks. Subsequently, patients were followed up on 8^th to 24^th week at 4 weekly intervals and then at 1 year. At each follow-up, patients were evaluated for signs of post-op infection at the surgical site, radiological signs of union, knee ROM, ability to bear weight, pain as assessed by VAS, and functional outcome at 1 year using Neer scoring.⁹ Lower limb full length scanogram to assess alignment was done at 1 year follow-up. Deviation of more than 10 degrees from anatomical axis of femur in antero-posterior full limb scanograms or more than 10 degrees of angulation in lateral radiograph were considered as mal-alignment. Delayed union was defined as a fracture that didn’t show any sign of healing after 6 months. Non-union was defined as a fracture which didn’t heal by 9 months and didn’t show any radiographic progression for 3 months.

The data analysis was done using SPSS-20. Student t-test was applied as a test of significance. A probability value of<0.05 was considered significant.

Ethical considerations: The study was conducted after obtaining permission from the institutional ethics committee (IEC). All the data collected as a part of this study was kept confidential. Patients’ identity will never be disclosed.

RESULTS

Of the 89 patients initially enrolled in the study, 2 patients lost to follow-up and 1 patient died of other medical reasons. So, 86 patients were finally included in the study. 44 patients were operated with LCP (group I) and 42 patients were operated with IMN (group II). There was no significant difference in mean follow-up duration in both groups (12.5±0.4 months in group I and 13.2±0.6 in group II).

The age, sex distribution of the patients, AO classification, mean follow-up and side of fracture is shown in Table 1.

Table 1: Comparison of age, sex distribution of the patients, AO classification, mean follow-up and side of the fracture of the 2 groups.

The mechanism of injury was found to be fall from standing height in 76.6% cases followed by RTA in 19% cases followed by assault in 4.4% cases.

Mean operative time and intra-operative blood loss in both groups are shown in Table 2 with IMN proving to be quicker procedure with smaller incision and better cosmesis.

6 patients in group I developed surgical site infection noticed at the time of suture removal. 2 patients recovered as the wound healed with IV antibiotics as per culture sensitivity and daily dressing. The subsequent follow-up of these 2 patients was uneventful with normal recovery. The other 4 patients were administered IV antibiotics as per culture sensitivity but didn’t show any improvement and gradually plate was exposed. Revision surgery was done at 4 weeks when the implant was removed and wound debrided. They were kept under antibiotic coverage for 6 weeks after which infection subsided completely and then they were taken up for revision surgery with plating and bone grafting. Their subsequent follow-up was normal and uneventful. No superficial or deep infection was documented in group II. Wound infections and subsequent post-operative complication rate were significantly lower in group II (Table 3).

There was a statistical difference in time till radiological union among the 2 groups (Table 3) with group I having mean time of union of 17.33±7.4 weeks while in group II it was 11.5±4.3 weeks (p<0.05). Union disturbance was seen more frequently in group I where 2 patients showed delayed union and 5 cases had non-union. Both cases of delayed union healed completely at 2 years follow-up with bone marrow aspiration from posterior superior iliac spin and injection at fracture site. Their subsequent follow-up was uneventful. 3 cases of non-union were a result of hardware failure (screw breakage) and other 2 were due to loss of reduction. Nonunion cases were treated with exchange implants and autologous bone grafting and eventually healed adequately. 3 cases in group II showed malalignment with 2 having varus and 1 valgus. Since the activities of daily living of these patients were not hampered because of this mal-alignment and patients were satisfied with the outcome, these patients were not further intervened. One nonunion in group II was operated with exchange nailing and healed satisfactorily. Non-union rates were found to be significantly high in group I.

Time till full weight bearing was significantly short in group II with 93% cases able to bear full weight by 12 weeks as compared to group I where 66% of cases could bear full weight by that time.

Knee ROM at 1 year was 110±5 degrees for group I and 116±6 degrees in group II. Though statistically insignificant, knee ROM at 1 year follow-up was better in group II (Table 3).

Knee pain at the end of 6 months as assessed by VAS, was present in 37.2% cases in group II against 16.5% in group I and was found to be statistically significant.

Functional outcome assessed by Neer scoring system at the end of 1 year was statistically insignificant between the two groups, (group I 88.6%, group II 81.5%).

DISCUSSION

Distal femur fractures have always remained a controversial subject to treat for orthopedic surgeons. In young patients it usually occurs following high-velocity trauma whereas in the elderly it is commonly due to low energy impact like fall from standing height. But the fracture is comminuted in most of the cases.^1-4 With improved technology and improved surgical methods, surgical fixation of these fractures has become main treatment option as opposed to conservative methods used earlier. Currently, locking compression plates and retrograde intramedullary nailing are the two modalities of treatment commonly used. Locking plates rely on the principles of open reduction, absolute stability, and interfragmentary compression for bone healing whereas intramedullary nails are less invasive, achieve reduction via indirect approach, and offer relative stability.¹⁰ Osteosynthesis with LCP has the benefit of achieving near-anatomical fixation because of direct reduction maneuver and also its use in osteoporotic bones which make a big number of fragility fractures in distal femur but extensive soft tissue dissection, damage to the periosteum and higher chances of infection are frequent pitfalls of LCP. Retrograde IMN, on the other hand, has the edge of being biological, not disturbing fracture hematoma because of indirect reduction, less soft tissue handling and no loss of blood supply to the bone as periosteum is left intact. Its disadvantages are lack of alignment control, posterior angulation, damaging the knee joint cartilage, risk of early OA knee and intra-articular effect of reaming debris.¹⁰

Numerous scales have been used for assessment of the functional outcome of the patients in distal femur fractures e.g., hospital special surgery score, Hammer score, Lysholm Gillquist scoring system (LGSS), etc.^11-13 We used Neer’s score and knee ROM at 1-year follow-up in our study to evaluate the functional outcome of patients because it emphasizes on the important aspects of daily life like pain, activities of daily living, return to work, etc.

Functional outcome at the end of 1 year was statistically insignificant in our study with respect to both Neer score and knee range of motion. This finding is consistent with many studies in the past despite having used different scoring systems. Markmiller et all using the Lysholm Gillquist score to compare LISS and RIMN, found no significant difference between the 2 groups in functional outcome.¹⁴ Demirtas et al, in their study used Sanders’s criteria, also announced similar outcomes in terms of duration of union, complications, and functional results.¹⁴ Gao et al and Gupta et al also have stated similar functional outcomes using HSS score.^11,9 However, Hoskins et al in a recent study using EuroQol-5 criteria have concluded in favor of IMN at 6 months follow-up with p=0.025 but the trend didn’t continue till 1-year follow-up (p=0.073) where it was insignificant at the end of 1 year.¹⁵

Time till radiological union was better in the IMN group in the present study with a mean time of 11.5 weeks compared to the LCP group (17.33 weeks) which was statistically significant (p<0.05). Similar results were obtained by Krishna et al in their prospective study with 40 patients.¹⁶ Union disturbance i.e., nonunion, delayed union, and malunion rates were found to be higher in the LCP group in the present study. This finding is accordant with that of study by Gao et al, Herrera et al, and Luzan et al whereas studies by Markmiller et al and Gupta et al have stated otherwise.^11,13,17,18

Malalignment (varus/valgus) was higher in the IMN group in our study but it was insignificant. Study by Markmiller et al showed similar results with no statistically significant difference.¹³ However, Zehntner et al found relevant malalignment in the LCP group (26%).¹⁹ Another study by Schandelmaier et al found 17.5% malalignment in the LCP group.²⁰ Muller et al reported 23% relevant axial deviation in LCP group.

Comparison of recent studies with result stated in their words has been mentioned in Table 4.

There were a few shortcomings of the present study, the most evident being the limited sample size. Our sample size wasn’t enough to make concrete findings. Further inclusion of elderly patient has also affected findings of the study as postoperative knee function comparison was compromised.

*Results and conclusion as stated in the original study

CONCLUSION

Both IMN and LCP have been successfully used in treatment of distal femur extra-articular fractures previously, each having their own set of advantages and disadvantages. But IMN proved to be a better modality of fixation of distal femur fracture fixation in our study with better radiological union time, lesser rate of infection, reduced intra-operative time, early return to activities of daily living, better cosmesis and better knee range of motion. Functional outcomes were also equivalent to LCP, if not more. Hence, we would hold IMN superior to LCP if done with proper principles of intramedullary fixation.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the institutional ethics committee

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