Tibial Plateau Fracture Following Anterior Cruciate ...

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Tibial Plateau Fracture Following Anterior Cruciate Ligament Reconstruction with a Bone-Patellar Tendon-Bone Allograft A Case Report Blake M. Bodendorfer, MD, Joshua A. Kotler, MD, Caitlin J. Thornley, MD, and William F. Postma, MD Investigation performed at Georgetown University, Washington, DC

Abstract Case: A 36-year-old woman sustained a medial tibial plateau fracture involving a tibial tunnel that had been used 4 years prior for an anterior cruciate ligament (ACL) reconstruction with a bone-patellar tendon-bone (BPTB) allograft in the same knee. At 26 months following open reduction and internal fixation of the tibial plateau fracture (6 years following the index ACL reconstruction), the patient returned to full activity. Conclusion: To our knowledge, this is the first report of a tibial plateau fracture following ACL reconstruction with a BPTB allograft, which adds to the paucity of literature discussing tibial plateau fractures following ACL reconstruction and discusses the potential predisposing factors to fracture such as ACL graft selection and surgical technique.

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ost anterior cruciate ligament (ACL) injuries are estimated to occur in the 30-year period between 15 and 45 years of age (accounting for approximately 47% of the population); the annual incidence of ACL injuries in these 3 decades of life is roughly 1 in every 1,750 persons1,2. Typically occurring in athletes, 70% of injuries result from noncontact, rapid deceleration resulting in external or internal rotational forces that are applied to the knee at a low flexion angle. Direct traumatic force applied to the knee accounts for the remaining 30% of injuries1. ACL reconstruction techniques include the use of a bone-patellar tendon-bone (BPTB), hamstring, or quadriceps tendon autograft, along with various allograft options. The 2 most common femoral tunnel preparation techniques are the anteromedial and transtibial approaches. Some advocate for the anteromedial technique, citing a more reliable anatomic reconstruction compared with the traditional

transtibial approach. However, current clinical practice guidelines have shown similar outcomes with both approaches3-8. ACL reconstruction has known complications, including stiffness, arthrofibrosis, infection, graft failure, and venous thromboembolism. Periarticular fractures in the setting of prior ACL reconstruction are rare; they have been reported in a limited number of cases in the distal aspect of the femur and in the proximal aspect of the tibia2,9-11. Such referenced periarticular fractures are distinctly different from traumatic tibial plateau fractures with concomitant ACL injury. To our knowledge, there are no prior reports of a postoperative tibial plateau fracture in patients who have undergone ACL reconstruction with a BPTB allograft. The patient was informed that data concerning the case would be submitted for publication, and she provided consent.

Written work prepared by employees of the Federal Government as part of their official duties is, under the United States Copyright Act, a ‘work of the United States Government’ for which copyright protection under that Act is not available. As such, copyright protection does not extend to the contributions of employees of the Federal Government prepared as part of their employment. Disclosure: The authors indicated that no external funding was received for any aspect of this work. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/A682). Disclaimer: The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government. LT Joshua A. Kotler, MC, USN, is a military service member. This work was prepared as a part of his official duties. Title 17 U.S.C. 101 defines a United States Government work as a work prepared by a military service member or employee of the United States Government as part of that person’s official duties.

JBJS Case Connect 2018;8:e34

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http://dx.doi.org/10.2106/JBJS.CC.17.00233

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Fig. 1

T I B I A L P L AT E AU F R A C T U R E F O L L O W I N G ACL R E C O N S T R U C T I O N W I T H A B O N E -P AT E L L A R T E N D O N -B O N E A L L O G R A F T

Fig. 2

Fig. 1 Anteroposterior radiograph of the left knee demonstrating the medial tibial plateau fracture. Fig. 2 Oblique radiograph of the left knee demonstrating the medial tibial plateau fracture, with evidence of the prior ACL reconstruction.

Case Report 36-year-old woman presented with the chief symptom of left knee instability with side-to-side movements after sustaining an ACL tear from a valgus injury while playing tennis 4 months prior. At the index presentation, she had elected to pursue nonoperative treatment with physical therapy and had been able to carry out the tasks of daily living; she had returned for treatment because she was unable to play tennis. At the time of repeat presentation, she demonstrated mild valgus alignment, a range of motion from 0 to 130, a grade-2B Lachman test, and a 11 pivot-shift test; no varus or valgus instability or signs of posterolateral involvement were evident. Radiographs demonstrated no signs of arthrosis. Review of prior magnetic resonance imaging (MRI) acquired at the time of injury was consistent with an ACL tear without substantial meniscal pathology. After discussing reconstruction options, she opted for a BPTB allograft. Examination under anesthesia demonstrated full range of motion from 22 to 130, a grade-2B Lachman test, a gradeII pivot-shift test, and stable examination with respect to the varus, valgus, posterior, and posterolateral planes. Diagnostic arthroscopy confirmed that the ACL was completely avulsed from its femoral origin with an empty notch sign. The lateral compartment demonstrated no chondral disease, but demonstrated a small, stable tear of the posterior horn of the lateral meniscus. The medial compartment demonstrated no meniscal or chondral pathology. The ACL remnant was removed,

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and a notchplasty was performed. The ACL guide was placed through a 2-cm incision on the anteromedial aspect of the knee, and the guide pin was passed into the ACL footprint on the tibia. Next, because of the initial treating surgeon’s preference for a larger bone block, an 11-mm tibial tunnel was created. A 35-mm femoral tunnel was drilled through the anteromedial portal. The graft was fixed to the femoral side with a 7 · 23-mm biphasic calcium phosphate and poly-L/D-lactide (PLDLA) interference screw and a 9 · 23-mm screw on the tibial side. There was no graft-tunnel mismatch, and the graft was fixed at 15 of flexion. Postoperatively, the patient followed a typical ACL rehabilitation protocol. She returned to tennis without issue. Four years following the ACL reconstruction with the BPTB allograft, the patient presented to the emergency department with acute left knee pain that had begun while playing tennis earlier that day. Examination revealed an ecchymotic and swollen left knee, with a slightly diminished range of motion that was limited by pain. Non-weightbearing radiographs revealed the expected postoperative changes in addition to a marginal fracture of the medial tibial plateau with an inferolateral displacement of approximately 2 mm (Figs. 1, 2, and 3). Computed tomography (CT) without contrast was notable for a comminuted oblique fracture of the medial tibial plateau, with involvement of the tibial spines anteriorly and the proximal tibial tunnel (Figs. 4 through 7). The dominant fracture fragment was not


Fig. 3

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Fig. 4

Fig. 3 Lateral radiograph of the left knee demonstrating the medial tibial plateau fracture. Fig. 4 Coronal CT view of the tibial plateau fracture. Fig. 5 Sagittal CT view of the tibial plateau fracture.

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0 to 130; there was no palpable or visible effusion, there was no medial or lateral joint-line tenderness, and the Lachman test was negative. Knee flexion and extension strength was 5 of 5. The surgical incisions had healed well, and the Lysholm knee score was 90 of 10012. Discussion ibial plateau fracture following ACL reconstruction is a rare complication that seldom appears in the literature. Of the cases that have been published, fractures have occurred between 2 weeks and 7 years postoperatively, with a mean occurrence at 25.6 months2,9-11. Most case reports do not specify which surgical approach had been utilized for femoral tunnel drilling; this limits the researcher’s ability to assess the correlation between the approach and an increased susceptibility to subsequent fracture. Additionally, no relationship has been observed between ACL reconstruction graft type and tibial plateau fracture management strategy. Although our patient’s fracture etiology has not been elucidated previously, several potential contributing factors have been discussed. Nyland et al. found that bone density, integrity, and area mass in areas such as the distal aspect of the femur and the proximal aspect of the tibia are negatively affected in all cases of ACL injury13. Even with appropriate surgical reconstruction and rehabilitation, return to baseline was not achieved. It also is recognized that bone strength decreases as a result of routine ACL reconstruction. Tunnel

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Fig. 6

Axial CT view of the tibial plateau fracture. This image shows fracture involvement of the tibial tunnel.

substantially displaced, but had a slight step-off from the articular surface of approximately 2 mm, as well as slight medial displacement with a 4-mm gap at the articular surface. There was a large joint effusion with a fat-fluid level and mild soft-tissue swelling of the infrapatellar region. CT showed that the medial tibial plateau fracture originated close to the tibial tunnel that had been used for the prior ACL reconstruction. Open reduction and internal fixation (ORIF) was planned by another orthopaedic surgeon in the practice. A medial approach to the proximal aspect of the tibia through the scar on the anteromedial aspect of the tibia from the prior ACL reconstruction was utilized. The medial collateral ligament (MCL) was split longitudinally, and the pes anserinus was exposed but not violated. After splitting the MCL longitudinally, keeping its proximal and distal insertions intact, a submeniscal arthrotomy was performed, which showed no involvement of the meniscus. The fracture was then reduced anatomically, and secured with a 3.5-mm medial proximal tibial locking plate. Radiographs confirmed the anatomic reduction, and the patient progressed through rehabilitation without complication. She returned to full activity by 5 months following the tibial plateau ORIF. At 26 months after the tibial plateau ORIF (6 years following the index ACL reconstruction with the BPTB allograft), the patient returned for final follow-up. She noted mild pain and swelling only with severe exertion during tennis matches. She was not using any assistive devices and had no feeling of instability or locking. Radiographs demonstrated complete fracture-healing (Figs. 8 and 9). The knee range of motion was

Fig. 7

Three-dimensional CT reconstruction of the tibial plateau fracture.


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Fig. 8


Fig. 9

Fig. 8 Weight-bearing anteroposterior radiograph after the ORIF. Fig. 9 Weight-bearing lateral radiograph after the ORIF.

drilling and pilot screw holes are known to cause stress risers and subsequent diminished bone-loading strength. Bone strength can be reduced by up to 90% when the drill-holeto-diaphysis-diameter ratio exceeds 20%14,15. Additionally, defects from tibial tunnels and autograft harvest sites may synergistically predispose patients to tibial plateau fractures2,10,11. Many authors believe that defects created by the tibial tunnel provide a larger contribution to stress-riser formation compared with defects from harvest sites because fractures, when they occur, are consistently observed in the tunnel region, independent of graft selection. This might explain the vast majority of cases demonstrating fractures that extend into the tibial tunnel2,9-11. Bioabsorbable screws have been discussed as a potential contributor because of variable rates of degradation that are not necessarily dependent on screw composition. As the screw is absorbed, the osseous defect first passes through a fibrofattytissue intermediate phase. In this phase, often asynchronous with screw absorption, the tibial tunnel widens, exacerbating the stress riser and predisposing the structure to fracture16. A number of reports discuss tibial plateau fractures in patients with BPTB autografts, but not with allografts17-19. It is possible that a BPTB allograft induces more tunnel resorption compared with a BPTB autograft, as demonstrated by Fahey and Indelicato20. Notably, the 11-mm tunnel that was created in our patient during the index ACL reconstruction is larger than many surgeons employ, and a smaller tunnel would have preserved more native bone.

Individual biology also may predispose patients to tibial plateau fractures following ACL reconstruction. With our patient, osteoporosis was an unlikely factor given her African-American ethnicity and young age at the time of fracture. Additionally, while she was taking lamotrigine, a non-enzyme-inducing antiepileptic medication, this newer anticonvulsant had not been shown to alter bone metabolism as have others21. Tibial plateau fractures following ACL reconstruction are exceedingly rare, and no consensus has been established regarding the potential contributions of graft selection or surgical technique. Possible predisposing factors to periarticular fractures following ACL reconstruction may include loss of bone density and integrity following ACL injury, a stress riser formed by tunnel drilling, tunnel widening associated with the use of bioabsorbable screws, and tunnels larger than the standard 9 to 10-mm diameter. Patientspecific factors include medication history and history of metabolic bone disorders. Additional studies should explore possible biologic and biomechanical etiologies of this complication. n

Blake M. Bodendorfer, MD1 Joshua A. Kotler, MD2 Caitlin J. Thornley, MD3 William F. Postma, MD1


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1Department

of Orthopaedic Surgery, Pasquerilla Healthcare Center, Georgetown University, Washington, DC


3University

of Arizona College of Medicine, Tucson, Arizona

E-mail address for J.A. Kotler: [email protected] 2Bone

& Joint/Sports Medicine Institute, Naval Medical Center Portsmouth, Portsmouth, Virginia

ORCID iD for J.A. Kotler: 0000-0002-6220-3829

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