Comparison of different locking plate fixation methods in distal tibia fractures

Taking into consideration rate of complications presented in this investigation we must underline that population of patients, who continued treatment and were present at all follow-up ambulatory check-ups, might not be representative due to the fact that patients who experienced serious complications that required re-operation are more eager to continue their treatment than those without any complaints. Thus higher prevalence of non-union and surgical site infection might be overestimated. In the literature, rate of those complications in patients with pilon type fracture is also high. Rate of infection varies depending on author from 5 to 37 % and rate bone union disorders often exceeds 20 % [5, 9, 10, 11].

In surgical treatment of fractures of distal tibia, proper choosing of approach plays a very important role. A well-planned and executed approach enables the surgeon to perform good fracture reposition as well as determines which type of fixation plate might be used. The most popular is the antero-lateral approach [12]. It allows proper exposition of lateral malleolus and distal tibia, especially its epiphysis [13]. With this approach precontoured, antero-lateral plate should be used for fixation of tibia fracture. Properly placed plate in this region is well covered with soft tissue, thus minimizing risk of problems with surgical wound healing. A possible complication in this approach is iatrogenic rupture of superficial peroneal nerve that is localized in this area.

In case of extra-articular fractures, or fractures with the main fragment localized on the medial part of distal tibia, the medial approach with use of medial pre-bent plate placed with the MIPO technique should be used. This approach does not allow proper exposure of fracture on the antero-lateral side of the distal tibia (Tillaux–Chaput fracture), and thus should not be used as a single approach in comminuted intra-articular fractures. Contraindication to this method is poor condition of skin and soft tissue in the area of the medial malleolus. A thin layer of soft tissue covering this place increases risk of having problems with wound healing above the plate, which may lead to greater number of surgical site infections. Moreover, when risk factors such as diabetes, arteriosclerosis of lower extremities, or smoking are present, then risk of infection is also much higher [14].

From a mechanical point of view it seems that fixation with a medial plate, as well as with antero-lateral plate, gives a comparable level of stability. Yenna et al. [15], in their research on anatomical models of distal tibia fractures from 2011, did not find any differences in strength of medial, or antero-lateral plate fixation, but there are no reports of clinical studies that would prove this statement.

Lee et al., in 2009, compared fixation with plates placed on medial or lateral sides of tibia. This research showed a slight advantage of fixation with the lateral plate. In cases of medial plates, incidence of surgical site infections was higher (p = 0.047), and patients more often complained of pain caused by implant localized in close proximity to the skin (p < 0.001) [9]. In our research there was no evidence that would sustain those statements. Similar incidence of surgical site infections was found in both subgroups treated with either medial, or antero-lateral plate. We believe that prevalence of infections depends mainly on the extent of injury, contusion of soft tissue, as well as on patients' individual risk factors.

In our analysis we showed that time to bone union was shorter in the group treated with medial plate (p = 0.053). Moreover, problems with bone healing were more often when antero-lateral plate was used (p = 0.08). Those differences are noticeable but none of them is statistically significant (p > 0.05). Also the fact that investigated groups were highly diversified when it comes to extent of injury should be taken under consideration. Most patients (18 out of 19) with high-energy, comminuted fractures type 43-C, were treated with antero-lateral plate. It might be that high rate of problems with bone union in this group was related not only to type of surgical approach and plate used, but also to energy and extent of injury. To sum up, factors that have influence on choice of approach and type of fixation in pilon fractures are type of fracture and condition of soft tissue [16, 17].

Analysing subgroups according to rigidity of fixation and usage of lag screws we found that slightly better functional results measured with AOFAS score were found in the group treated with bridging plate (82 points vs 75 points). No differences in time to bone union, or prevalence of complications were observed. Hasenboehler et al. [18], in 2007, showed good results of treatment of distal tibia fractures with medial plates using the MIPO technique with interfragmentary lag screws (rigid fixation). The authors stated that to avoid the risk of prolonged secondary bone healing and plate bending complications in fractures 43-A and 43C1-C2 interfragmentary compression is needed. Horn et al. [19], in a study from 2011, found that results of treatment with rigid fixation, or with bridging plate are similar, but patients with interfragmentary screws were allowed full weight bearing earlier (around 11 weeks) than patients with bridging plates (around 15 weeks). Mass of callus was smaller in cases of rigid fixation with use of lag screws. In our study the majority of patients (55.6 %) with extraarticular fractures 43-A were treated with interfragmentary screws and most patients (64.3 %) with mulitifragmentary intraarticular fractures 43-C were treated with bridging plate techinique. Because of this asymmetry regarding group assignment the comparative study is not realiable.