Surgical Management of Distal Tibia Fracture: Towards An Outcome-based Treatment Algorithm

Introduction: Distal tibia fractures are frequently associated with an extensive soft tissue injury which then leads to a higher risk of complications such as infection, non-union and eventually poor overall outcome. The purpose of this study is to measure the outcome of distal tibia fractures treated with internal fixation, external fixator or Ilizarov external fixator(IEF). We aim to propose an algorithm for management of distal tibia fractures by evaluating the treatment options, outcomes and risk factors present. Material and Methods: This study is a cross-sectional study of all distal tibia fractures treated surgically in Tengku Ampuan Rahimah Hospital, Klang from 1st January 2016 till 30th June 2018. Patient records were reviewed to analyse the outcomes of surgical treatment and risk factors associated with it. Results: Ninety-one patients were included with a mean age of 41.5 years (SD = 16.4). Thirty-nine cases (42.9%) were open fractures. Thirty-eight patients (41.8%) were treated with internal fixation, 27 patients (29.7%) were treated with IEF and 26 patients (28.6%) were treated with an external fixator. Among open fractures cases, no significant finding can be concluded when comparing each surgical option and its outcome, although one option was seen better than the other in a particular outcome. Initial skeletal traction or temporary spanning external fixator in close fractures reduced the risk of mal-alignment (p value=0.001). Internal fixation is seen superior to IEF and external fixator in close fractures in term of articular surface reduction (p value = 0.043) and risk of mal-alignment (p value = 0.007). Conclusion: There is no single method of fixation that is ideal for all pilon fractures and suitable for all patients. This proposed algorithm can help surgeons in deciding treatment strategies in the challenging management of distal tibia fractures to reduce associated complications.


INTRODUCTION
Distal tibia fracture is a fracture that involves the metaphyseal area of the distal tibia and may extend to its weight-bearing articular surface 1 . It is also known as tibial pilon fracture or tibial plafond fracture if it involves the articular surface. Etienne Destot introduced the term tibial pilon in 1991 where pilon is a French word for pharmacist's pestle that has a similar shape to the area of distal tibia metaphysis extending 5cm from ankle joint 2 . Plafond also comes from a French word that means ceiling which describes the horizontal articular surface of the distal tibia 2 .
The incidence of distal tibia fracture ranged from as low as 3 per 10,000 per year to as high as 28 per 10,000 per year depending on age and gender 3 . Pilon fractures are rare. They account for 1% of all lower limb fractures, 3% to 10% of all fractures of the tibia1 and approximately 20% to 40% are open fractures 4 . These fractures are usually associated with high energy trauma, caused by fall from heights or motor vehicle accidents thus they are frequently associated with extensive soft tissue injury and are often open fractures. These associations lead to a higher risk of infection, malunion, non-union and eventually poor overall outcome.

Surgical Management of Distal Tibia Fracture: Towards An
Outcome-based Treatment Algorithm with subtypes C1 (simple articular, simple metaphyseal fracture), C2 (simple articular, multifragmentary metaphyseal fracture) and C3 (multifragmentary articular and metaphyseal fracture) 5 . Additionally, intra-articular distal tibia pilon fracture is categorised into three types by Ruedi and Allgower depending on articular surface dislocation and fracture comminution 6 .
Distal tibia fracture can be treated with a wide range of treatment methods including a variety of external fixators, intramedullary nailing and internal plate fixation. Minimally invasive techniques have been preferred recently with the hope of better outcomes [7][8][9] .
Historically, distal end tibia fractures were treated conservatively with traction followed by early range of motion. This approach was based on the concept of ligamentotaxis where soft tissue attachment to the bone will reduce the fractures but then it was realised that there was no soft tissue attachment to reduce the fractures in a severely comminuted fracture 10 .
Later on, open reduction and internal fixation became more accepted after publications by Ruedi and Allgower and research by the AO group. In their publication, Ruedi and Allgower developed a reproducible technique and stated fundamental operative principles for the management of intra-articular distal tibia fracture with 70 percent of their cases showing good or excellent late results 6,11 . However, other authors were unable to reproduce the result.
Studies on distal tibia fractures showed a variety of results but none can demonstrate that one is specifically better than the other for every type of this fracture. Hence, it is challenging for a surgeon to decide what is best for a patient considering other presenting factors which may increase the risk of complications.
The purpose of this study was to measure the outcome of distal tibia fractures treated with internal fixation, external fixator or Ilizarov external fixator. The study also aimed to identify the complications following surgically treated distal tibia fractures and to identify risk factors associated with the outcomes. Finally, we would like to propose an algorithm for the management of distal tibia fractures. A superficial infection or pin tract infection was defined as any sign of an infection that healed with or without antibiotics and by just wound care and dressing. Deep infection was defined as an infection that needs surgical debridement in operating theatre 12 . Osteomyelitis was defined as deep bone infection shown clinically or radiographically and confirmed by surgical findings intraoperatively. Delayed union was defined when the union was delayed more than 23 weeks 13 . Non-union was defined as a fracture that has not healed nine months after the operation and there is no visible progress of healing during the last three months 14 . Mal-alignment was described as when there is more than 5° of angulation in any plane 15 . Articular incongruency was noted when there was any articular step seen radiologically after surgical intervention. Ankle arthritis was identified when there was osteophytes formation, subchondral sclerosis with or without reduced joint space 16 .

MATERIALS AND METHODS
In our centre, the surgical option of treatment was determined by the surgeon on-call or surgeon in charge of the patient's respective ward. Upon presentation to the emergency department, all patients were managed using standard trauma resuscitation protocol. Open fractures were irrigated, covered with intravenous cefuroxime then sent for thorough wound debridement and joint bridging external fixator. Triangular frame cross ankle external fixator was usually employed with two Schanz pin over the tibia proximal to fracture and a Denham pin through the calcaneum connected with two bars. Associated lateral malleolus fracture was managed with a rush rod or intramedullary wire. Near all external fixator cases were performed by registrars.
For closed fractures, first, the patient's limb was put on a splint, elevated and regular cryotherapy was applied. Then, the patient was put on calcaneal traction or keep on the splint until definite surgery. Definitive treatment and time to surgery were decided depending on soft tissue condition and fracture configuration. In many open fracture cases, if the fracture reduced well with spanning external fixator, especially in poor soft tissue condition, the external fixator was kept as definitive management until soft callus formation before a decision was made to convert to cast if wound healing was permissible. Ilizarov external fixator (IEF) is generally opted for in cases of severe comminuted open fracture while open reduction, internal fixation (ORIF) is usually chosen in cases of closed fracture and simple extra-articular fracture.
All data were analysed using IBM SPSS version 23. The descriptive data were expressed as frequency with percentage as well as mean ± standard deviation unless otherwise stated. Data were cross-tabulated and evaluated statistically using Chi-square test or Fisher's exact test. Association between outcome of surgical treatment of distal tibia fracture, types of treatment and risk factors were evaluated. A p-value of 0.05 or less was considered significant.

RESULTS
A total of 91 patients fulfilled the inclusion criteria during the data collection period. Five patients were lost to followup, therefore excluded. Due to limitations of our patient's data registry, any data that was not available was marked as missing data. Then, when comparing external fixator and IEF, external fixator cases were seen to have a higher risk of malalignment.
Patients with an open extra-articular fracture that were treated with external fixators had a 55.6% risk of malalignment when compared to IEF with 28.6% risk (Table  III). Still, putting on skeletal traction or temporary external fixator before definitive fixation in open fracture cases lowed the risk of infection and risk of alignment deformity. Open fracture cases that were not on skeletal traction or temporary external fixator were complicated with 100% risk of infection and 50% risk mal-alignment compared to patients with skeletal traction or temporary external fixator at 43.3% risk of infection and 38.9% risk of mal-alignment (Table IV).
Nevertheless, patients treated with IEF had a higher risk of delayed or non-union compared to those that were treated with internal fixation. Open fractures that were treated with internal fixation achieved union on time while those on IEF were complicated with either delayed union (27.3%) or nonunion (18.2%) (Table III).  (Table III).
Meanwhile, in close intra-articular fracture, no infection where seen in 70% of cases treated with internal fixation when compared to 80% with IEF and 100% with external fixator. Similar to the significant finding in close extraarticular fracture, no mal-alignment was seen in close intraarticular fracture treated with internal fixation or IEF when compared to 100% risk of mal-alignment in patient treated with external fixator (p-value 0.007). Both internal fixation and IEF had a similar risk of delayed or non-union with 80% of both groups united in the expected time. In terms of articular congruency, internal fixation was associated with better articular surface reduction when compared to IEF (p value = 0.043). 90.9% of closed intra-articular fractures treated with internal fixation had no articular step compared to 25% in the IEF group, although good articular surface reduction was also seen in external fixator (Table III).
Initial skeletal traction had significant effect on reducing risk of mal-alignment in close fractures (p value = 0.001). No significant effect of initial traction was seen on the risk of infection or articular surface reduction (Table IV).
The occurrence of ankle arthritis was seen more frequently in patients treated with IEF or external fixator as compared to patients treated with internal fixation in close fracture. However, this finding was not seen in open fractures (Table  III).       Other findings included a mean union time of 25 weeks (SD =10) seen in close extra-articular fractures, and that the time to definitive surgery for closed fractures treated with internal fixation was not a significant risk factor for infection. Closed fractures that were treated with internal fixation and which were not complicated with infection were mostly were operated on between 3-29 days (median 11 days) posttrauma. This overlapped with time to the definitive procedure for cases complicated with infection that were operated between 7-16 days (median 13 days) post-trauma.
Non-smoker patients had a slightly better union at 68.0% when compared to smoker patients at 54.2%. Non-diabetic patients also have a better union rate and a somewhat lower risk of infection (Table V). Comparative studies on this type of fracture had conflicting results. One study reported a higher risk of infection in ORIF compared to external fixation. Lower mean clinical scores and other outcomes were observed for ORIF although not statistically significant. More complications were also seen in patients treated with ORIF 20 . Another study showed excellent or good objective and subjective results in dynamic external fixation but noted high rates of superficial infections and arthrosis 21 . ORIF also was noted to has 2% rate of amputation, 2% rate of arthritis, 2% rate of chronic osteomyelitis drainage, 2% rate of wound dehiscence and 13% rate of skin necrosis 19 .
Other comparative studies on ORIF versus external fixator showed that patients treated with external fixation had more complications than ORIF, and ORIF had a higher union rate 22,23 . Lower clinical scores and more loss of range of motion were also seen in the external fixator group 22 . While, two-staged external fixator and plate fixation, rates of infection and arthrodesis were reported lower compared to primary ORIF or single staged procedure 24 .
In our study, we divided each type of fracture according to the type and articular involvement. Then, we observed the risk of complications and the outcome of each type of treatment in each group. By comparing the risk of complications of each treatment method, we built the algorithm of management of distal tibia fracture as shown in Fig. 1.
Among open fracture cases, when comparing each surgical option and its outcome, no significant finding can be concluded although one type of surgical option was seen better than the other in a particular outcome. For close fractures, we recommend putting on skeletal traction or temporary spanning external fixator as first line of treatment as this has been shown to reduce the risk of malalignment. Internal fixation is seen superior to IEF and external fixator in close fractures in terms of articular surface reduction and risk of mal-alignment. Although not statistically significant, in close fractures, internal fixation has a better union rate and lower risk of ankle arthritis but a slightly higher risk of infection.
Nevertheless, we would not advocate internal fixation for closed fractures with poor soft tissue condition such as blisters and superficial wounds. A severely comminuted fracture that is not amendable to hold with plate and screws should not proceed for internal fixation.
Comparing the results of our study to other previous studies, there are both similar and conflicting results. Our proposed algorithm differs in few aspects. First, we do not advocate for all patient to be put on skeletal traction or spanning external fixator as initial temporary measure before definitive fixation. Secondly, we believe spanning external fixator has its role to be a definitive fixation in selective cases. Lastly, we suggest internal fixation as a preferred method of fixation for close fracture over IEF. Having said that, our study is limited by inadequate patient record systems, multiple surgeons involvement, unequal distribution within the group, study design, small sample size and short study period. Nonetheless, previous studies also were unable to produce specific evidence due to biases and other confounding factors presenting with this type of fracture.
For future studies, it is worth including intramedullary nail which is another recommended method of treatment that has gained much attention in recent years, especially for type 43A in view of its minimally invasive approach.

CONCLUSION
In conclusion, there is no single method of fixation that is ideal for all pilon fractures and suitable for all patients. This proposed algorithm can help surgeons in deciding the strategy of treatment while considering other associated factors. The fracture pattern, soft-tissue condition, patient comorbidities, surgical skills and experience as well as hospital resources must always be taken into account. However, further studies are needed to prove the effectiveness of this algorithm.