Clin Orthop Surg.  2015 Jun;7(2):269-274. 10.4055/cios.2015.7.2.269.

Pure Varus Injury to the Knee Joint

• Yoo JH
• Lee JH
• Chang CB

• KMID: 2164556
• DOI: http://doi.org/10.4055/cios.2015.7.2.269

Abstract

A 30-year-old male was involved in a car accident. Radiographs revealed a depressed marginal fracture of the medial tibial plateau and an avulsion fracture of the fibular head. Magnetic resonance imaging showed avulsion fracture of Gerdy's tubercle, injury to the posterior cruciate ligament (PCL), posterior horn of the medial meniscus, and the attachments of the lateral collateral ligament and the biceps femoris tendon. The depressed fracture of the medial tibial plateau was elevated and stabilized using a cannulated screw and washer. The injured lateral and posterolateral corner (PLC) structures were repaired and augmented by PLC reconstruction. However, the avulsion fracture of Gerdy's tubercle was not fixed because it was minimally displaced and the torn PCL was also not repaired or reconstructed. We present a unique case of pure varus injury to the knee joint. This case contributes to our understanding of the mechanism of knee injury and provides insight regarding appropriate treatment plans for this type of injury.

Keyword

Knee injury; Varus; Posterolateral complex; Medial plateau fracture; Posterior cruciate ligament

MeSH Terms

Adult
Fibula/*injuries/surgery
Humans
*Knee Injuries/complications/surgery
Male
*Multiple Trauma/complications/surgery
*Tibial Fractures/complications/surgery

Figure

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  Fig. 1 Anteroposterior (A) and lateral (B) plain radiographs showing a mid-marginal fracture of the medial tibial plateau and an avulsion fracture of the fibular head.

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  Fig. 2 Sagittal (A-C), coronal (D, E), and axial (F) magnetic resonance imaging scans (proton density; repetition time = 3,900 msec, echo time = 15 msec). (A) An undisplaced, minimal avulsion fracture was clearly seen. (B) Although the anterior cruciate ligament maintained its integrity, the posterior cruciate ligament was torn, whereas the lateral meniscus was intact (A). (C) The posterior horn of the medial meniscus was torn. (D) A compressive mid-marginal fracture of the medial tibial plateau was also present. The avulsed fibular head had attachments to the lateral collateral ligament (D) and the biceps femoris tendon (E). (F) Marginal fracture of the medial plateau and avulsion fracture of Gerdy's tubercle were obvious on the axial image of the tibial plateau.

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  Fig. 3 Surgical treatment for posterolateral corner (PLC) injury in the current case. (A) The PCL was exposed by a longitudinal curvilinear incision and the peroneal nerve was identified and protected. (B) The avulsed lateral collateral ligament and biceps tendon were secured using whipstitches, which were then passed through the fibular tunnel for PLC reconstruction, and the structures were reduced at their origins and stabilized by tying the sutures. (C) Finally, we completed the augmented reconstruction of the lateral collateral ligament and popliteofibular ligament component of the PLC using a figure of 8-fibular sling method.

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  Fig. 4 Postoperative anteroposterior (A) and lateral (B) radiographs showing reduction of the marginal fracture of the medial tibial plateau and the avulsed fibular head and adequate reconstruction of posterolateral structures.

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  Fig. 5 Postoperative 2-year anteroposterior (A) and lateral (B) radiographs showing bony union of medial tibial plateau and minimal osteoarthritic change.

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  Fig. 6 Schematic illustration of the compressive marginal lesion of the medial tibial plateau (I, II, III) and avulsive marginal lesions of the lateral tibial plateau (IV, V, VI, VII). I: at the anterior portion by hyperextension varus, II: at the mid-medial portion by pure varus, III: at the posterior portion, which could have occurred via compression or avulsion mechanism by the semitendinosus, VI: avulsion of Gerdy's tubercle by the iliotibial band, V: Segond fracture cause by avulsion fracture of the lateral capsular ligament or anteroinferior band of the lateral collateral ligament, VI: avulsion of the anteroinferior portion of the fibular head by the conjoined tendon of the lateral collateral ligament and biceps femoris tendon, VII: avulsion of the styloid process of the fibular head by the arcuate complex.

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  Fig. 7 Photographs (A,B) and schematic illustration (C) showing the injury mechanism of this pure varus injury case (arrow: varus force).

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