a 54-year - old male presented with painful , swollen bilateral knees following a minor motorcycle accident where he fell from a motorcycle traveling at a relatively low speed .
the accident occurred when a driver backed into the street in front of him riding a motorcycle in an alleyway .
radiographs revealed schatzker type iv tibial plateau fractures involving medial condyles in both knees ( fig .
two years and four months before the accident , the patient had undergone an arthroscopic acl reconstruction using double - bundle technique with tibialis posterior allograft and medial collateral ligament ( mcl ) repair on his left knee at a hospital . in spite of our efforts to obtain more information , such as the type of the screw used and
tunnel size created in the previous operation , additional information from that hospital was not available .
he had the same surgery on his right knee about eight months ago at another hospital .
an arthroscopic acl reconstruction was performed using single - bundle technique with a 25 mm femur endobutton ( smith & nephew endoscopy , andover , ma , usa ) , a 9 mm in length and 25 mm in diameter bio - absorbable interference screw ( conmed linvatec , largo , fl , usa ) , and tibialis posterior allograft .
mcl femoral tensioning using an 11 mm bone staple was performed during the operation with removal of a spiked washer and a screw on the left tibia that had been implanted in the previous acl reconstruction .
due to severe pain , knee joint stability and range of motion could not be assessed .
computed tomography was performed to evaluate the fracture pattern in relation to the acl tibial tunnel , which demonstrated intra - articular involvement of split fractures on the bilateral medial tibial plateaus .
1 ) . considering the unique nature of the fractures , we decided to attempt treatment and confirm the state of the previously reconstructed acl later by second - look arthroscopy .
fracture reduction on the left side was achieved intraoperatively under fluoroscopic control , which was followed by fixation using a six - hole medial locking compression plate ( lcp medial proximal tibial plate ; depuy synthes , oberdorf , switzerland ) with a 6.5 cancellous screw and a washer ( depuy synthes ) for anatomical reduction of the intra - articular surface .
subsequently , removal of the spiked washer and screw on the right tibia was done . in the same way , utilizing a four - hole medial locking compression plate ( lcp medial proximal tibial plate ) with a 6.5 cancellous screw and a washer ( depuy synthes ) , fracture reduction and fixation on the right side was performed . the planned second - look arthroscopic examination for confirming the previously reconstructed acl state
was achieved three weeks afterwards because the patient had suffered from fever and urinary tract infection since immediately after surgery .
examination under general anesthesia revealed negative anterior lachmann test and pivot shift test with feeling of firm as the endpoint .
however , we could not identify the degree of screw resorption or tunnel widening . physical therapy with continuous passive motion was started immediately postoperatively , and protected weight bearing was maintained for two postoperative months . at five months follow - up ,
follow - up radiographs of the patient showed callus formations with healed fractures in both tibias ( fig .
tibial plateau fractures presenting as a serious complication after acl reconstruction are rare , and only isolated cases have been reported .
interestingly , in most of these cases , the tibial plateau fractures occurred through the tibial tunnel .
authors of these reports suggested that the presence of the tibial tunnel could be the main factor in predisposing the patient to the fracture acting as a stress riser3,4,5,6,7 ) .
more recently , a case described by a. gobbi et al.6 ) had some interesting features .
tibial plateau fractures had occurred after primary anatomic double - bundle acl reconstruction following minimal trauma of running backwards during a soccer game in their case .
they suggested that two tunnels made in the proximal tibia might have caused a greater increase in local stresses around the tunnels with less bone available to withstand the applied load compared with a single tunnel .
we could not find any studies that specifically measured bone strength of the tibia following tibial tunnel drilling or compared the mechanical effect of two tunnel creation to one tunnel creation .
however , it has been documented that bone defects , such as screw holes , can concentrate stress and significantly decrease bone resistance to bending and torsional forces8,9 ) .
for instance , diaphyseal drill holes with a diameter greater than 20% of the bone have been shown to reduce bone strength by 55%-90%8,9,10 ) . in our case , the fracture pattern had some unique and distinct features . although the patient fell from a motorcycle while riding it at a relative low speed , the fractures involved bilateral tibias and occurred through tibial tunnels that had been formed during previous acl reconstruction .
furthermore , we could not identify other injuries to the articular structures in our patient .
he had undergone an arthroscopic acl reconstruction using double - bundle technique on his left knee and the same surgery using single - bundle technique on his right knee .
fortunately , the acls on both knees were found to be intact when examined by second - look arthroscopy .
although we were not able to find differences between the effect of single and double - bundle reconstructions on this unique fracture in our patient , it was obvious that the fracture lines on the patient 's tibias extended into the tibial tunnel .
our study suggests that a transosseous tibial tunnel alone can somehow act as a stress - riser that decreases strength at the level of proximal tibial metaphysis .
we would like to emphasize that the surgeon must be very careful in tunnel placement and should not perform extensive bone removal during acl reconstruction .
also , it is crucial to be aware of the possible occurrence of this , albeit rare , postoperative complication considering most cases required surgical fixation of the fractures .
 tibial plateau fractures after arthroscopic anterior cruciate ligament ( acl ) reconstruction are rare , and only isolated cases have been reported . 
 the authors describe a case of bilateral medial tibial plateau fracture following a minor motorcycle accident in a patient who underwent arthroscopic acl reconstruction in the past . 
 two years and four months before the accident , the patient underwent an arthroscopically assisted acl reconstruction using double - bundle technique on his left knee at a hospital . 
 he had the same surgery using single - bundle technique on his right knee about eight months ago at another hospital . 
 the fractures in his both involved knees occurred through the tibial tunnel and required open reduction with internal fixation . at three weeks after fixation , a second - look arthroscopy revealed intact acls in both knees . at five months 
 follow - up , he was able to walk without instability on physical examination . 
 follow - up radiographs of the patient showed callus formations with healed fractures . 
Case Report
Discussion