a Departamento de Ortopedia, Santa Casa de São Paulo, São Paulo, SP, Brasil
b Serviço de Ortopedia e Traumatologia, Hospital Israelita Albert Einstein, Universidade Federal de São Paulo (Unifesp), São Paulo, SP,Brasil
c Instituto de Ortopedia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo, SP, Brasil
d Escola Paulista de Medicina, Universidade Federal de São Paulo (Unifesp), São Paulo, SP, Brasil
Introduction
Reconstruction surgery on the anterior cruciate ligament(ACL) performed arthroscopically presents a high rate of good results.1More than 100,000 new cases are performed in theUnited States every year.2However, this procedure is not freefrom complications,3with an incidence rate of between 1.8%and 24%.
The complications that have been described include:arthrofibrosis, patellar fracture, "Cyclops" lesions, synovitis,patellar tendinitis, pain in the graft donor area and osteolysis,3among others. The commonest of these is joint stiffness.4Fracturing of the proximal tibia is a serious complication thathas only been described in a few cases in the literature.5,6Inthe present report, we describe this complication.
This case consisted of a fracture of the proximal extrem-ity of the tibia that occurred in a patient 4.5 months after anarthroscopic operation to reconstruct the ACL.
Case report
The project for this study was approved by our institu-tion's research ethics committee under the protocol number5985/2011.
The patient was a 17-year-old male who was attended atour hospital, with a history of spraining his left knee afterstepping into a hole in the asphalt when crossing a street. Hearrived at the emergency service with a condition of pain inhis left knee and leg, accompanied by functional limitationand inability to bear weight on the affected leg. He said thathe had undergone ACL reconstruction surgery 4 months previ-ously, in which a graft from the ipsilateral patellar tendon hadbeen used. Radiographs of the knee were produced in fontaland lateral views, from which an extra-articular fracture of theproximal tibia was diagnosed. The fracture line reached theregion of the anterior tibial tuberosity (ATT), which was the sitefrom which the bone plug for the bone-patellar tendon-bonegraft had been harvested (Figs. 1 and 2). The patient underwentsurgical treatment in which open reduction and internal fixa-tion using a plate and screws were performed (Figs. 3 and 4). Noloosening of the tibial interference screw that had been usedin the ACL reconstruction was seen. The patient presentedgood evolution with the treatment that had been proposedand did not present any functional alterations or any alter-ations in specific tests for evaluating the reconstructed ACL.Consolidation of the fracture was achieved by the end of the
fourth postoperative month. The patient returned to his recre-ational sports activities and rated his degree of satisfaction ashigh. One year after the operation, the implant was removedbecause of local discomfort that the patient reported (Fig. 5).
Discussion
Fracturing of the tibial plateau at the site of the tibialtunnel after ACL reconstruction has only been described afew times in the literature.5,6Some published studies havereported occurrences of fractures of the tibial plateau fol-lowing ACL reconstruction using autografts from the gracilisand semitendinosus.4,5Others have used bone-patellar-bonegrafts6,7and allografts from the Achilles tendon.8This eventis probably independent of the graft used, but there are the-ories stating that the bone that is drilled through in orderto construct the tibial tunnel is subject to stress that leadsto fatigue when torsional forces are applied during flexion.8The presence of a tibial tunnel is thought to act like a corticaldefect, which is a factor predisposing toward fractures.5,7Inthis regard, when a patellar graft is used, harvesting the boneplug would increase the susceptibility of the proximal tibia tofracturing. This has been well documented, since a corticaldefect diminishes bone resistance in situations of torsionalforces.
In the case in question, the center of the fracture was inthe donor area of the bone plug. This bone defect acted syn-ergically in association with the drilling of the tibial tunnel,thereby increasing the zone of fragility and allowed tibial frac-turing due to low-energy trauma.
Concentration of stress on an anterior point of the proximaltibia caused by fixation screws that alter the bone mechan-ics would also be a predisposing factor.7Despite the lack ofspecific studies, a biomechanical study by Brooks et al. foundthat drilled holes with diameters greater than 20% of the bonewidth decreased the torsional capacity by 55%.12One addi-tional factor that might play a role in fracture developmentfollowing ACL reconstruction is widening of the bone tun-nel, which may occur in up to 68% of the cases.13The factorcausing this is still unknown, but it is believed to be an autoim-mune phenomenon even though no research has confirmedthis hypothesis.
Most authors have opted to perform surgical treatment onthese fractures, with open reduction and fixation using platesof a variety of models, even though this is a difficult surgicalprocedure secondary to a surgical complication. Most of thecases described evolved well through the treatment.
In the case reported here, surgical treatment was also cho-sen, with medial access to the proximal tibia and positioningof an L-shaped support plate. The patient evolved withoutimmediate or late complications and presented full range ofmotion and consolidation of the fracture 4 months after thetreatment.
Fracturing of the tibial plateau after arthroscopic ACLreconstruction is a rare complication that is still littledescribed in the literature. Studies have shown good evolutionof this complication following surgical treatment, even thoughthe procedure has a high degree of technical difficulty. In thecase reported here, the patient evolved satisfactorily after theoperation, with consolidation of the fracture of the left tibialplateau, achievement of full range of motion of the knee joint,a return to work activities and even a return to recreationalsoccer practice.
Conflicts of interest
The authors declare no conflicts of interest.
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