CHAPTER 23 Reconstruction of Malunited Ankle Fractures
DECISION MAKING AND RECONSTRUCTION
The premise for reconstruction of a malunited ankle fracture is joint preservation. Frequently, the joint may appear to be irreparable, with articular wear and erosive changes on the medial or lateral plafond. Even with these more advanced changes, however, restoring the alignment of the ankle is worthwhile. Most of these cases involve a malunion or a nonunion, or both, of the fibula. Occasionally, the medial malleolus or the posterior tibia also is involved in this malunited fracture, necessitating simultaneous correction. Lateral weight-bearing radiographs and a computed tomography (CT) scan of the ankle are helpful to plan the reconstruction. The CT scan is not necessary but does aid in determining the required degree of rotation of the fibula. It is always worth the effort to attempt a reconstruction of the malunited ankle fracture. If this fails, an arthrodesis and joint replacement are still options. The results with osteotomy of the fibula or the tibia, or both, are excellent even in ankles with considerable deformity and arthritis (Figures 23-1 and 23-2). In some situations, a reconstruction simply cannot be performed for technical reasons, and an arthrodesis is the best alternative. An important point in this context, however, is that an arthrodesis is not the only treatment option after severe trauma (Figure 23-3).
Figure 23-1 A-C, This ankle fracture malunion was associated with considerable shortening and external rotation of the fibula in addition to ankle arthritis. An arthroscopic debridement of the joint and removal of the hypertrophic tissue in the medial gutter was followed by a lengthening of the fibula and syndesmosis stabilization. D-F, Note the marked improvement in the alignment of the ankle as well as the apparent joint space.
Figure 23-2 A, Despite severe deformity and joint incongruency associated with nonunion and malunion of fractures of the fibula and the medial malleolus and erosion of the lateral tibial plafond, the reconstruction is worth attempting. B, Note the overall improvement in the alignment of the ankle with revision of the medial malleolus fixation and lengthening of the fibula.
Figure 23-3 A and B, The patient was a 25-year-old woman who presented 6 weeks after an ankle open fracture-dislocation, which was treated with removal of the malleoli and insertion of a large retrograde pin for stabilization, resulting in development of an osteomyelitis of the calcaneus. After debridement, the ankle appeared stable, and other than periodic brace use, no additional treatment was provided. C-F, Five years later the ankle was stable, albeit somewhat arthritic, with restricted motion and a fixed equinus deformity.
Débridement: Arthroscopy or Arthrotomy?
A decision needs to be made whether arthroscopic debridement of the joint is to be performed simultaneously. Arthroscopic evaluation of the joint is very helpful in these cases to document and stage the extent of ankle arthritis. In particular, arthroscopy is indicated for evaluation of a suspected posterior and inaccessible chondral defect that would not be visible with anterolateral arthrotomy. The hypertrophic tissue between the medial malleolus and the talus must be excised from the medial gutter for the reposition of the talus. Surprisingly small amounts of tissue in the medial gutter can actually block the correct medial shift of the talus back into the mortise (Figure 23-4). Fibular malunion generally is associated with a lateral translational deformity of the talus with an increase in the medial clear space, and the medial joint recess must be debrided, under visualization afforded by either arthrotomy or arthroscopy.
Figure 23-4 A 37-year-old patient presented for treatment after nonoperative management of an ankle injury. A and B, Note the shortening and external rotation of the fibula, the loss of the lateral talofibular alignment, and the increase in the medial joint clear space. C and D, Treatment consisted of arthroscopic debridement of the medial joint, arthroscopic cheilectomy and removal of bone debris and hypertrophic scar, and lengthening of the fibula. The overall ankle structure and in particular the distal talofibular alignment have been restored.
For this procedure, a vertical incision is made medial to the anterior tibial tendon directly over the anterior notch of the medial ankle over a 2-cm length. The incision is deepened through the joint. Then the capsule is incised, and the hypertrophic synovium, capsule, and scar are excised completely from the medial gutter. The insertion of a rongeur is useful; it should be turned around 180 degrees to ensure that the medial gutter is completely free and that the talus is mobile. The medial gutter will again be checked subsequently for correction of the fibula malunion as the talus is pushed over medially.
Fibular and Medial Malleolus Deformity and Osteotomy
The fibula is commonly shortened and externally rotated in a malunion, although only one of these may be present, determining the type of osteotomy and bone graft. Ideally, it should not be necessary to strip the entire syndesmosis in order to lengthen the fibula. In cases in which the syndesmosis must be included in the procedure, such as arthrodesis requiring creation of a tibia pro fibula, then the syndesmosis should be taken down completely (Figures 23-5 and 23-6). If the fibula is externally rotated and not shortened, then a derotational osteotomy can be performed without lengthening, thereby preserving the syndesmosis (Figure 23-7).
Figure 23-5 Lengthening of the fibula without internal rotation. A, The osteotomy is made transversely, and the syndesmosis is separated with a laminar spreader. B and C, In this case, a syndesmosis arthrodesis was performed and a cancellous graft was inserted before the lengthening procedure. D-F, Once the fibula was out to length, guide pins were inserted distally to lock it in place; then the graft was inserted and a plate applied.
Figure 23-6 Treatment for a short and internally rotated fibula. A, Before osteotomy, pins were inserted more proximally to prevent proximal shift of the fibula. B, Once the length was corrected with a laminar spreader, multiple pins were inserted to maintain the length. C-E, Then the bone graft was inserted and a custom fibula-contoured plate (Orthohelix, Akron, Ohio) was applied.
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