Symptomatic fibular non-union after hybrid lateral closing wedge high tibial osteotomy: a report of two cases

INTRODUCTION

Lateral closing wedge high tibial osteotomy (LCW-HTO) is a well-established procedure for the treatment of medial compartment knee osteoarthritis with varus malalignment. Hybrid LCW-HTO is effective in treating severe varus deformity combining the principle behind medial open wedge and lateral close wedge osteotomy with rigid fixation. Adequate shortening of the fibula is mandatory to aid tibial correction and is commonly achieved either by excision or oblique osteotomy. Fibular non-union after LCW-HTO has been frequently reported in the literature, with incidences ranging from 10–20%.^1-3 However, the majority of these non-unions remain asymptomatic and do not affect the functional outcome. Large series, including our previously published cohort, have shown that only a small minority of fibular non-unions become painful and require revision surgery.⁴

Symptomatic fibular non-union is therefore uncommon and sparsely reported. When present, it may manifest as localized pain, tenderness, or a pricking sensation during weight bearing due to abnormal motion, poor fragment contact, or mechanical irritation of surrounding soft tissues. This case report describes two patients with persistent symptoms more than one year after hybrid LCW-HTO, each representing a different fibular osteotomy technique, and discusses the possible etiological factors leading to symptom development.

CASE REPORT

Case 1: symptomatic non-union after oblique fibular osteotomy

A 61-year-old male patient underwent hybrid LCW-HTO for medial compartment osteoarthritis. Standard surgical protocols were used. Fibular shortening was achieved using an oblique mid-diaphyseal osteotomy. The immediate post-operative course was uneventful, and tibial osteotomy site united satisfactorily with good correction.

At 12 months post-operatively, when planning for tibial plate implant removal, the patient complained of persistent, localized lateral leg pain associated with a sharp pricking sensation during walking. There were no neurological symptoms. Clinical examination revealed mild focal tenderness over the fibular osteotomy site without signs of infection. The tibial osteotomy site was asymptomatic. Plain radiographs demonstrated a fibular non-union. Computed tomography confirmed absence of bridging callous with hypertrophic callous formation and minimal fragment contact. Given the chronic symptoms and radiological findings, surgical intervention was planned. The patient underwent fibular non-union revision with open reduction, debridement and plate fixation with autologous iliac crest bone grafting. At 6-month follow-up, radiographs confirmed union, and the patient reported complete resolution of pain and pricking sensation (Figure 1).

Case 2: symptomatic non-union after segmental fibular excision

A 62-year-old female patient underwent hybrid LCW-HTO with fibular shortening performed by segmental excision of approximately 2–2.5 cm of the mid-diaphyseal fibula.

Tibial alignment correction and union progressed uneventfully. Despite satisfactory knee function, the patient presented at 12 months post-operatively with persistent lateral leg pain and discomfort localized to the fibular region, described as pricking sensation during ambulation (Figure 2).

Clinical examination again revealed point tenderness over the fibular defect. Radiographs and CT scans demonstrated a well-established fibular non-union with a segmental gap and no evidence of callous formation (Figure 2). Given the persistence of symptoms beyond one-year, surgical management was undertaken. Revision surgery consisted of fibular plating spanning the defect with autologous iliac crest cancellous and strut bone grafting (Figure 3). At 6 months, complete radiological union was achieved, and the patient was symptom-free, with no recurrence of pain at final follow-up (Figure 4).

DISCUSSION

Fibular non-union is the most frequent complication related to fibular management in LCW-HTO, yet it is predominantly a radiological finding without clinical symptoms and significance. In our previously published series on fibular management in hybrid LCW-HTO, only approximately 5% of fibular non-unions were symptomatic and required revision surgery. The rarity of symptoms suggests that additional mechanical or biological factors are necessary for a fibular non-union to become painful. Recent literature further supports this concept. Most cases remain asymptomatic due to compensatory stability from surrounding soft tissues once union is achieved. Symptomatic non-union tends to present late in the post-operative course, often beyond one year, and is unlikely to resolve spontaneously. In such cases, surgical stabilization is justified based on persistent focal symptoms rather than radiographic findings alone.⁵

Ramanoudjame et al demonstrated that progression from fibular non-union to subsequent symptom development is strongly influenced by both mechanical and patient-related factors. These include reduced obliquity of the fibular osteotomy plane resulting in more horizontal cuts, insufficient fragment contact (<50%), higher body mass index, and excessive micro motion at the osteotomy site, all of which compromise stability and biological healing potential. Alternative methods of fibular management, such as proximal fibular head osteotomy and proximal tibio-fibular joint separation, have been described to avoid diaphyseal fibular non-union. However, concerns regarding peroneal nerve injury and proximal tibio-fibular joint instability have limited the routine use of these techniques, and diaphyseal fibular osteotomy or excision remains the most commonly employed approach.^2-6

From a biomechanical perspective, horizontal or minimally oblique osteotomies result in reduced contact area and increased shear forces, leading to instability and non-union. In segmental excision, the absence of fragment contact leads to loss of intrinsic stability, which may permit micro motion and mechanical irritation. Symptomatic presentation, such as pricking or sharp pain, is likely due to abnormal motion at the non-union site, local periosteal irritation, or interaction with adjacent soft tissue. Once symptoms persist beyond one year and there is no radiological progression of union, spontaneous resolution is unlikely. Surgical revision with stable plate fixation and biological augmentation using autologous cancellous and/or strut bone graft reliably addresses both mechanical instability and biological deficiency. Consistent with previous literature, both of our patients achieved complete union and symptomatic resolution within 6 months following revision surgery.^7-10

CONCLUSION

Although fibular non-union after hybrid LCW-HTO is common, it is rarely symptomatic. Persistent localized pain or pricking sensation beyond one year should prompt evaluation for symptomatic fibular non-union. Both oblique osteotomy and segmental excision techniques can result in symptomatic non-union under unfavourable mechanical conditions. Plate fixation combined with autologous iliac crest bone grafting is an effective and reliable treatment, leading to predictable union and excellent clinical outcomes.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

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