Outcome of the Treatment of Distal Tibia Fractures by Minimal Invasive Locked Plate – A Short Term Study

Background Treatment of fracture distal tibia is challenging. Classic open reduction and internal plate fixation requires extensive soft tissue dissection and causes periosteal injury. The locking screw-plate interface allows fracture fixation without plate–bone adherence, thus preserving the fracture hematoma, and reduces the risk of nonunion by maintaining microvascular circulation within the cortex and its investing tissues. Material & Methods This study included 33 patients of age between 18 to 62 years with extra-articular and simple intra-articular fracture of distal tibia. All fractures were fixed by minimally invasive technique with pre-countered distal tibia locking plate under image intensifier control. The American Orthopaedic Foot and Ankle Society (AOFAS) scale was used for functional assessment. Results Out of 33 there were twelve 43-A1, five A2, five A3, five B1, three B2, two C, one C2 fractures. There were 29 closed fracture and four open fracture (three type I and one type II). The overall mean time of union was 16.3 weeks. The mean AOFAS score was 93 points. In all 30 cases there were no wound problems, whereas three cases had superficial wound infection. No any cases needed secondary procedure for healing of bone. Conclusion The short-term results shows that minimally invasive locked plating is good solution for the challenging distal tibia fracture. This technique minimizes soft tissue complication and provides good union and functional outcome.


Introduction
Treatment of fracture distal tibia is challenging because of the limited soft tissue, the subcutaneous location, and poor vascularity of distal tibia.Although many options are available for treatment of distal tibia fracture, the best one remains controversial [1,2].External fixation with ilizarov frame, ankle spanning hybrid fixator with or without minimal internal fixation is good option especially, if it is associated with extensive soft tissue injury.But it is associated with complications like pin-track infections malunions or nonunions [3], and inaccurate reduction [4], especially of intraarticular fractures.Classic open reduction and internal plate fixation requires extensive soft tissue dissection and causes periosteal injury.That is why it is associated with high rates of complications, including infection (range 8.3-23%) and delayed union and nonunions (range 8.3-35%) [5].Closed intramedullary nailing do not disturb fracture's hematoma and maintains the integrity of the soft tissue coverage, but it is technically difficult, unstable fixation and can lead to malunion [6].MIPPO involves inserting a plate in a subcutaneous extraperiosteal tunnel, bridging the fracture site, which is then secured proximal and distal to the fracture zone.Minimally invasive plate osteosynthesis (MIPPO) aims to reduce iatrogenic soft-tissue injury and damage to bone vascularity and preserve the osteogenic fracture hematoma [7].The locking compression plate device allows the screws to lock to the plate, therefore creating a stable, fixed-angle device [8,9].The locking screw-plate interface allows fracture fixation without plate-bone adherence, thus preserving the fracture hematoma, and reduces the risk of nonunion by maintaining microvascular circulation within the cortex and its investing tissues [10,11].The aim of our study was to assess shortterm clinical and radiological results of treatment of extra-articular and simple intra-articular fracture of distal tibia with MIPPO technique using locking compression plates regarding time to union, complications, and functional outcome using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle score [14].

Material & Methods
This was a prospective study that was carried out between November 2011 to December 2015 in the orthopaedic department of Nobel medical college and teaching hospital, Biratnagar.This study was approved by the ethical committee.The written informed consent was taken from all patients for participation in the study.This study included Gustilo- All the cases with fracture distal tibia who presented to orthopaedic outpatient or emergency department were evaluated clinically and plain radiographs of the distal tibia and the ankle were sent.A computed tomography scan of the distal tibia and the ankle was obtained in patients with extension of the fracture to the joint.Each injury was carefully evaluated for the extent of soft tissue injury, fracture pattern, bone comminution, bone loss, articular extension and the need for fixation of fibula.All cases were iniatially managed by temporary immobilization of limb by long leg posterior slab.Open injuries were treated with intravenous antibiotics, adequate wound debridement, and lavage before any definitive fixation.Definitive surgery was planned when the ankle swelling subsided, and the 'wrinkle sign' was present.Fractures were classified according to the AO comprehensive classification system [12], whereas open injuries were classified according to the Gustilo and Anderson classification [13].

Operative technique
Patients were operated upon under regional anesthesia on a standard radiolucent orthopedic table.A pneumatic tourniquet was inflated on the thigh after giving intravenous antibiotic.Patients were positioned supine on the operative table.All the patients were treated with medial distal tibia anatomical locked plate using the MIPPO technique using image intensifier.We fixed the fibula fracture if it was syndesmotic, displaced infrasyndesmotic, or suprasyndesmotic associated with comminution, impaction, or shortening at the tibia fracture.It was fixed first by using MIPPO, open plating, or intramedullary thick K-wires before tibial fixation.The main fracture fragments of the distal tibia were aligned and reduced by manual traction.If the reduction was difficult, a dissector, Schanz screw, or periosteal elevator was used as a joystick to assist in reduction.Then the fracture fragments were fixed with individual percutaneously inserted lag screws if possible.Cannulated screws and K-wires were used before plating to fix the intraarticular extension of the fracture if required.An entry site is developed over the distal tibia through a 4 to 5 cm curved anteromedial incision centered over the medial malleolus, and the plate is then inserted from the distal to the proximal, through a tunnel between the periosteum and the intact overlying tissue.Compared with the other side, alignment, limb length, and rotation were assessed and adjusted before fixing the plate.It was reassessed after the plate was secured by one screw to the proximal and distal fragments.If satisfactory, the remaining screws were applied.At least three bicortical screws were inserted proximal to the fracture, whereas bicortical or unicortical screws were inserted distal to the metaphyseal fracture using as many of the distal plate holes as possible through small stab wounds.The stab incisions were irrigated and closed with routine skin sutures, and then the wound was dressed.
Postoperatively, the limb was maintained in the elevated position and immobilized by using a removable below knee back slab for 2 weeks.Parenteral antibiotics were continued for 3 days postoperatively, and then oral antibiotics were given for an additional week.Active range of motion and non-weight-bearing crutch walking while still in the hospital was allowed, and weight bearing as tolerated was allowed over time depending of the fracture pattern, fracture healing, and the stability of fracture fixation, but most patients could bear weight at least partially at 6 to 8 weeks.If the fracture was intra-articular, we kept the patients non-weight-bearing for the first 2 weeks, and asked them to start toe-touch weight bearing starting from the fourth postoperative week, and outpatient physiotherapy was carried out under supervision to maximize the range of motion of the foot and the ankle.Patients were evaluated clinically, functionally, and radiologically (plain antero-posterior and lateral radiographs) at 2, 6 weeks and then every 6 weeks from surgery till union.Clinical and functional outcomes were assessed using the Clinical Rating Systems for the ankle-hindfoot developed by the American Orthopedic Foot and Ankle Society [14].

Statistical analyses
Statistical analyses were done by using SPSS (version 18).Quantative variables were expressed as mean ± SD.Categorical values were expressed as a percentage and compared using the 2test.P value less than 0.05 was considered significant.

Results
Out of 33 patients available for complete follow up, there were 20 men and 13 women, with a mean age of 37 years (range 18-62 years).Twelve patients were injured in road traffic accidents, twelve patients had fall from height and nine patients fracture due to slip and fall.Five patients had angular deformities less than or equal to 5 degree-four varus, one valgus deformities.No patients had any rotational, recurvatum, procurvatum or implant failure.Limb length discrepancy of <1cm was found in three patients but all were asymptomatic.All patients had almost full ROM comparable to the other side of limb of same patients.In seven patients, the plate was prominent but this did not necessitate plate removal.The AOFAS score was obtained at a minimum of 12 weeks after the start of full weight bearing.The mean score was 93 points (range 71 to 100 points).In our study, we utilized the standard operative table, which necessitated the presence of an extra assistant to maintain reduction.We also used devices like the bone clamp to facilitate reduction.The anatomical plate itself was used as a mold.Percutaneous lag screws were applied whenever the fracture configuration allowed its insertion.This technique was described in most of the series we reviewed [18,22].

Conclusion
Out of the fractures managed by this method, most of them showed uncomplicated healing within a reasonable period of time.Functional assessment using the AOFAS scoring system showed excellent outcomes.The complication rate was minimal.The MIPPO method can be used safely in the management of distal tibial fractures even with simple articular extension.The procedure, however, is technically demanding, requiring the availability of appropriate tools and surgical implants.Careful follow-up of the patients is recommended.This technique, as confirmed by our results, minimizes the complication rate, promotes union within a reasonable period of time.The limitation of our study was small sample size, shorter follow up and there were no comparision with other modalities of treatments.[24] Gupta RK, RohillaRK, Sangwan K, Singh V, Figures

Table 1
[7, preserve the osteogenic fracture hematoma.They are believed to improve healing rates and decrease complications[7,16,17].In our study, the overall mean time for union was 16.3 weeks.These results are similar to those obtained by Oh et al. [18], who, reported a mean time to union of 15.2 weeks (range: 12-30 weeks) in 20 patients using contoured limited contactdynamic compression plate.In addition, in 2004, Redfern et al. [19] reported a mean of 23 weeks (range: 18-29 weeks) to union with no complications in 20 patients with closed fractures of the distal tibia, which was more than our results.Collinge et al. [20] reported a longer mean time to union of 35 weeks (range: 12-112 weeks) in 26 patients with high energy distal tibial metaphyseal fractures, as their series included open and closed fractures with high soft-tissue injuries, which were not included in our study.On the other hand, Collinge and Protzman [21] reported a mean of 21 weeks (range: 9-60 weeks) in 38 patients with distal tibial low-energy metaphyseal fractures, which we found to be compatible with our results.Ahmad et al. [11] retrospectively reviewed 18 patients with distal tibial metaphyseal fractures treated with locked distal tibial plates and reported a rather lengthy average time to union of 23.1 weeks (range: 8-56 weeks).Although the technique used by Ahmadet al. [22] is the same as ours, we believe the discrepancy was due to the complexity of the fracture in their series and due to a rather smaller sample size.However, with time to union varying from one study to another, we believe MIPPO still provides a faster time to union than does open plating.In the study done by Yang et al. [23] reported an average of 27.8 weeks (range: 18-36 week) in 14 patients with 43A distal tibial fractures managed by using the open plating technique.