Assessing The Potential Of Realignment Fibula Osteotomy For Distal Fibula Malunion

The primary goal of ankle fracture management is to improve the functional outcomes of patients and decrease complications. All facets of surgical care for ankle fractures continue to evolve but the foundation of treatment remains achieving anatomic healing of the ankle mortise. The talar dome bears more weight per unit area than any other joint surface and is extremely sensitive to even small tibiotalar incongruences.¹

Understanding ankle joint mechanics is important for a successful outcome. Fractures disrupt the congruency and stability of the joint. With fracture displacement, the talus faithfully follows the fibula.¹Greater than 2 mm of shortening (or lateral shift) or greater than 5 degrees of external rotation of the fibula significantly increases the contact pressures in the ankle joint that may lead to post-traumatic degenerative arthritis.²Therefore, it is imperative to realign the fibula anatomically to restore a symmetric, congruent ankle joint.

Reestablishing articular congruity and stability are most important for a successful outcome. Restoring anatomic length, rotation and obliquity to the fibula is essential. In a 21-year follow-up of supination-external rotation type ankle fractures (SER II-IV), Donken and colleagues reported 92 percent of patients had an excellent or good result when surgeons restored articular congruency.³Similarly, in a 22-year follow-up of pronation-external rotation type ankle fractures (PER III-IV), the same authors reported 90 percent excellent or good results when surgeons achieved anatomic reduction.⁴

Malalignment of the fibula and the resultant shifting of the talus leads to altered contact pressures in the ankle joint, which leads to post-traumatic arthritis. The following case study highlights the importance of restoring the fibula to anatomic length.  

Case Study: How A Reconstructive Fibular Osteotomy Can Resolve A Non-Healing Trimalleolar Fracture

A 55-year-old woman sustained a left trimalleolar ankle fracture while living in the Dominican Republic. She had open reduction with internal fixation (ORIF) with fixation of the distal fibula and medial malleolus. Postoperatively, she was immobile for approximately six weeks, subsequently transitioned to weightbearing and began physical therapy. She reported pain and joint stiffness throughout the entire recovery period.

While she was still in the Dominican Republic, she had hardware removed from the medial malleolus. This surgery did not resolve her symptoms and she continued to complain of pain and joint stiffness.  

The patient presented to my office approximately nine months after surgery. She complained of persistent pain, swelling and stiffness of the ankle joint, difficulty walking, and impairment of activities. I performed a comprehensive history and physical exam. She ambulated with an antalgic gait. The patient also had painful and limited ankle joint range of motion as well as severe pain with palpation along the joint line. She had full, pain-free range of motion of her hindfoot. Radiographs and a computed tomography (CT) scan demonstrated a malunited distal fibula fracture, non-uniform joint space narrowing and hardware (plate and screws) along the distal fibula.

We discussed both surgical and non-surgical treatment options in great detail. After careful consideration, the patient elected for surgery. I proposed ankle arthroscopy and a reconstructive fibular osteotomy to avoid or postpone the sequela of post-traumatic degeneration. The goals of the osteotomy were to restore anatomic length and correct the angular and rotational deformities of the fibula, thereby restoring the normal ankle biomechanics, and halting the progression of joint degeneration. In addition, I planned to perform ankle arthroscopy to further inspect the joint, remove scar tissue and adhesions, and address chondral and osteochondral lesions.

The patient was supine on the operating room table under general anesthesia. I prepped and draped her left lower extremity in the usual sterile fashion. For the arthroscopic portion of the procedure, I placed the patient’s leg in a thigh holder and used a non-invasive ankle distractor to improve visualization. I established standard anteromedial and anterolateral portals. Initial visualization was challenging due to limited capsular mobility and significant scarring and fibrosis.

Utilizing an arthroscopic shaver to help ensure adequate visualization, I performed further debridement to remove adhesions and fibrosis, and address chondral lesions. After performing thorough joint lavage and completing the arthroscopic portion of the procedure, I removed the thigh holder and the non-invasive ankle distractor.  

I then directed my attention to the lateral ankle. I placed an incision along the distal fibula and carried careful dissection down to expose the fibula. I removed the hardware and performed a transverse fibula osteotomy at the level of the malunion. I used a laminar spreader to distract the osteotomy. I verified appropriate lengthening and rotation of the fibula with intraoperative fluoroscopy. After confirming alignment, I interposed an appropriately sized allogenic tricortical bone graft to fill the gap. After utilizing a 1/3 tubular plate for fixation, I closed the wound in layers and applied a bulky compressive dressing with a posterior splint.

Initial postoperative management included non-weightbearing and immobilization of her ankle. The patient began range of motion exercises of her ankle when the skin incision healed. The patient transitioned to partial and then full weightbearing as radiographic healing of the osteotomy and the allogenic tricortical bone graft progressed to incorporation.

At the patient’s most recent followup appointment (10 months after surgery), the osteotomy was healed and the graft was fully incorporated with the fibula in good anatomic alignment. She achieved a reasonable increase in ankle joint range of motion and reported pain relief.    

In Conclusion

Based on the available literature, corrective osteotomies for fibular malunion have good or excellent results in more than 75 percent of patients.5 Corrective osteotomy of fibular malunion may potentially produce considerable improvement provided that the patient does not have significant degenerative changes before surgery. The development of degenerative changes is not fully predictable. Therefore, it is advisable to reconstruct a fibular malunion soon after one makes the diagnosis.5

In this particular case, I proposed a distraction fibular osteotomy to avoid or postpone the sequela of posttraumatic degeneration. Ankle arthrodesis may be needed as a secondary procedure in cases in which there is persistent pain and stiffness.

Dr. Bevilacqua is in private practice at North Jersey Orthopaedic Specialists in Teaneck, NJ. He is board-certified in both Foot and Reconstructive Rearfoot and Ankle Surgery by the American Board of Foot and Ankle Surgery (ABFAS). He is a Fellow of the American College of Foot and Ankle Surgeons (ACFAS).  

References

1. Yablon IG, Heller FG, Shouse L. The key role of the lateral malleolus in displaced fractures of the ankle. J Bone Joint Surg Am.1977; 59(2):169-73.
2. Thordarson DB, Motamed S, Hedman T, et al. The effect of fibular malreduction on contact pressures in an ankle fracture malunion model. J Bone Joint Surg Am. 1997. 79(12):1809-15.
3. Donken CC, Verhofstad MH, Edwards MJ, van Laarhoven CJ. Twenty-one-year follow-up of supination-external rotation type II-IV (OTA type B) ankle fractures: a retrospective cohort study. J Orthop Trauma.2012; 26(8):e108-14.
4. Donken CC, Verhofstad MH, Edwards MJ, van Laarhoven CJ. Twenty-two-year follow-up of pronation external rotation type III-IV (OTA type C) ankle fractures: a retrospective cohort study. J Orthop Trauma. 2012; 26(8):e115-22.
5. Van Wensen RJA, van den Bekerom MP, Marti RK, van Heerwaarden RJ. Reconstructive osteotomy of fibular malunion: review of the literature. Strat Traum Limb Recon. 2011; 6(2):51-57.

Editor’s note: For a related article, check out “A Closer Look At Arthroscopy For Ankle Fractures And Post-Fracture Defects” in the September 2009 issue of Podiatry Today.