Fixing the Difficult Ankle Fracture: Tips and Tricks

Rajrishi Sharma, M.D.
Department of Surgery, McMaster University

Brad A. Petrisor, MSc, M.D., FRCSC
Assistant Professor, Department of Surgery,
McMaster University
Hamilton, ON

Ankle fractures are amoung the most common fractures encountered by orthopaedic surgeons1-3. Despite this, however, observational studies suggest that malreduction following open reduction and internal fixation of unstable fractures may be as high as 24% of cases when assessed using standard radiographs and 52% using computerized tomography (CT)3,4. Complexity of ankle fracture fixation increases with involvement of the posterior malleolus, fibular bone comminution, with bone loss and marginal impaction of the plafond. With adequate preoperative planning and intraoperative techniques, successful fixation of these complex ankle fractures can be obtained.

 

petrisor1
Figure 1: Posterolateral approach with peroneal tendons retracted superiorly.

The literature is conflicted regarding the appropriate fixation for posterior malleolus fractures as well as the indications for fixation2,5,6. Biomechanical and clinical data to date suggests fixation of the posterior malleolar fragment when it is greater than 25-30%5,7-9. As well, stable, anatomic fixation of the posterior malleolus has been shown to biomechanically increase the stability of the syndesmosis5. Two common techniques exist to repair the posterior malleolus, including the percutaneous anterior-posterior lag screw technique and the open posterior-lateral Harmon approach2. The Harmon approach is a longitudinal posterior fibular incision with dissection between the flexor hallucis longus and peroneal brevis (Figure 1). This open technique has a few advantages: 1) it allows for direct visualization of fracture reduction, 2) allows the application of a posterior buttress plate at the apex of the fracture and 3) the postero-lateral incision allows for concomitant fibular fixation. The posterior malleolus, depending on size, can commonly be fixed with a 1/3rd tubular plate. The plate is placed non-contoured as it will contour itself with placement of the initial screw (just proximal to the posterior fracture line) which then helps reduce the fracture fragment. This direct reduction and application of a buttress plate with minimal increased morbidity are advantages of this open approach.

Anatomic reduction of the lateral malleolus is critical to minimize increased contact stress and post-traumatic osteoarthritis4. However, difficulty in reconstruction arises when there is severe comminution or bone loss10. In these situations, both preoperative and intra-operative techniques may help achieve a satisfactory reduction.

Intra-operatively opening the syndesmosis to verify reduction of the fibula within the incisura fibularis can help judge anterior-posterior position4. Preoperative assessment of the contralateral talocrural angle is a valuable tool to determine length. Using the talocrural angle, abnormal fibular shortening is reflected by a linear relationship. That is, approximately one degree of narrowing equals one millimeter of shortening4. The three Weber and Simpson criteria provide additional intra-operative radiographic measurements to help determine fibular length4,11. These include: 1) congruity of joint space, 2) an intact Shenton's line of the ankle (distal anteromedial border of the fibula involved in the tibiofibular joint), and 3) an unbroken curve between the lateral talus and the peroneal groove of the fibula. Using these criteria, the surgeon and patient can avoid the complications associated with a malunited fibula.

petrisor2
Figure 2: Post reduction radiograph of posterolateral dislocation and subsequent open reduction internal fixation with posterior plating technique.

Finally, identification of tibial marginal impaction is crucial to achieve joint reduction12,13. Failure to do so predisposes the patient to accelerated post-traumatic arthritis14. A high index of suspicion for medial marginal impaction should be present in ankles that underwent supination-adduction injuries13 and lateral marginal impaction in ankles that have undergone a pronation-abduction injury. Identification can be difficult to appreciate on plain radiographs, therefore preoperative CT may be necessary. These impaction fractures should be reduced and fixed. Bone grafting may be necessary depending on the size of the impacted fragment.

Posterior malleolus fractures, highly comminuted fibula fractures with or without bone loss, and medial and lateral tibial marginal impaction are three of the most common pitfalls of the complex ankle fracture. Other less common pitfalls which are usually identified include: the repair of a comminuted medial malleolus, vertical fracture of the medial malleolus, the malrotated fibula and syndesmosis injuries. With appropriate caution, identification of these common pitfalls in ankle fracture fixation can help avoid many postoperative complications.

References

  1. Brown, O., D. Dirschl, and W. Obremskey, Incidence of Hardware-Related Pain and Its Effect on Functional Outcomes After Open Reduction and Internal Fixation of Ankle Fractures. Journal of Orthopaedic Trauma, 2001. 15(4): p. 271-274.
  2. Werner, C., et al., Ankle Fractures: It Is Not Just A "Simple" Ankle Fracture. The American Journal of Orthopedics, 2007. 36(9): p. 466-469.
  3. Gardner, M., et al., Malreduction of the tibiofibular syndesmosis in ankle fractures. Foot and Ankle International, 2006. 27: p. 788-792.
  4. Chu, A. and L. Weiner, Distal Fibula Malunions. Journal of the American Academy of Orthopaedic Surgeons, 2009. 17(4): p. 220-230.
  5. Bekerom, M.V.D., D. Haverkamp, and P. Kloen, Biomechanical and Clinical Evaluation of Posterior Malleolar Fractures. A Systematic Review of the Literature. J Trauma, 2009. 66: p. 279-284.
  6. Hartford, J., et al., Contribution of posterior malleolus and deltoid ligament. Clin Orthop Relat Res, 1995. 320: p. 182-187.
  7. Lindsjo, U., Operative treatment of ankle fracture dislocations. A follow-up study of 306/321 consecutive cases. Clin Orthop Relat Res, 1985. 199: p. 28-38.
  8. Broos, P. and A. Bisschop, Operative treatment of ankle fractures in adults: correlation between types of fracture and final results. Injury, 1991. 22: p. 403-406.
  9. Haraguchi, N., et al., Pathoanatomy of the posterior malleolar fractures of the ankle. J Bone Joint Surg Am, 2006. 88: p. 1085-1092.
  10. Limbird, R. and R. Aaron, Laterally Comminuted Fracture-Dislocation of the ankle. The Journal of Bone and Joint Surgery, 1987. 69(6): p. 881-885.
  11. Weber, B. and L. Simpson, Corrective Lengthening osteotomy of the fibula. Clin Orthop Relat Res, 1985. 199: p. 61-67.
  12. Coonrad, R., Fracture-Dislocations of the Ankle Joint with Impaction Injury of the Lateral Weight Bearing Surface of the Tibia. Journal of Bone and Joint Surgery, 1970. 52: p. 1337-1344.
  13. McConnell, T. and P. Tournetta, Marginal Plafond Impaction in association with supination-adduction ankle fractures: a report of eight cases. J Orthop Trauma, 2001. 15(6): p. 447-449.
  14. Kellam, J. and J. Waddell, Fractures of the Distal Tibial Metaphysis with Intra-articular Extension - The Distal Tibial Explosion Fracture. The Journal of Trauma, 1979. 19(8).

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