Distal tibial fractures are a poorly recognised complication with fibula free flaps

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1 CASE-BASED REVIEW Ann R Coll Surg Engl 2015; 97: doi / X Distal tibial fractures are a poorly recognised complication with fibula free flaps A Durst, J Clibbon, B Davis Norfolk and Norwich University Hospitals NHS Foundation Trust, UK ABSTRACT The fibula free flap is ideal for complex jaw reconstructions, with low reported donor and flap morbidity. We discuss a distal tibial stress fracture two months following a vascularised fibula free flap procedure. Despite being an unrecognised complication, a literature review produced 13 previous cases; only two were reported in the reconstructive surgery literature, with the most recent claiming to be the first. The majority of these studies treated this fracture non-operatively; none reported their patient follow-up. Each case presented with ipsilateral leg pain, which has been cited as an early donor site morbidity in as many as 40% of fibula free flap cases. It is known that the fibula absorbs at least 15% of leg load on weight bearing. Studies have shown severe valgus deformities in up to 25% of patients with fibulectomies. We treated our patient operatively, first correcting his worsening valgus deformity with an external fixator, then reinforcing his healed fracture with a long distal tibial plate. We believe that this complication is underreported, unexpected and not mentioned during the consenting process. By highlighting the management of our case and the literature, we aim to increase awareness (and thus further reporting and appropriate management) of this debilitating complication. KEYWORDS Fibula free flap Donor site morbidity Tibial stress fracture Oral cancer Accepted 17 December 2014 CORRESPONDENCE TO Alexander Durst, E: al_durst@hotmail.com The osseocutaneous fibula free flap has been used in mandibular reconstruction since described by Hidalgo in The flap properties are ideal for complex jaw reconstructions, as a single stage procedure. Despite being technically challenging, 2 it has good bone length, the long vascular pedicle offers a significant advantage over other reconstructive options 3 and there is low reported flap morbidity. 4 Although a wide variance in donor site morbidity has been reported, it is rarely considered substantial enough to affect patient function. 5,6 While fibular resection in paediatric patients is known to be associated with valgus deformity of the developing ankle, 7 it has been stated that only 10% of the distal fibula is required to maintain ankle stability. 8 We describe a case of a tibial stress fracture with valgus deformity as well as a series of cases from the literature, highlighting a potentially underreported complication following a fibular free flap procedure. Case history A 67-year-old ex-smoker was referred to the head and neck multidisciplinary team with an aggressive T4 N2 M1 right mandibular adenocarcinoma, diagnosed on computed tomography and magnetic resonance imaging requested by his general practioner. He had presented initially with a mental neuropathy but there was no obvious soft tissue swelling on clinical examination. He underwent right-sided partial mandibular resection and block dissection with immediate reconstruction by vascularised free fibula flap, harvested in standard fashion; 11cm of the distal fibula was left. Following surgery, he was immobilised in plaster for a week and was allowed subsequently to fully weight bear as tolerated. At this stage, he had no pain and he had an uneventful discharge from hospital. Nine weeks after discharge, the patient presented to the accident and emergency unit with a six-day history of increasing ankle pain and a swollen, tender medial malleolus. Clinically, he had a valgus deformity. Radiography showed a transverse distal tibial shaft fracture (Fig 1). It was decided to address this deformity surgically once he had finished his adjuvant chemotherapy. During this 12- week interim period, he was treated non-weight bearing in a below-knee plaster (Fig 2). However, despite showing clinical and radiological signs of fracture union, his valgus deformity had worsened to 27 (Fig 3). The valgus deformity was treated with a tibial osteotomy, framed correction with an Ilizarov circular frame and strict non-weight bearing for eight weeks (Figs 4 and 5). After deformity correction, a long (13-hole) anterolateral Ann R Coll Surg Engl 2015; 97:

2 Figure 3 Anteroposterior and lateral radiography, 12 weeks after fracture, demonstrating radiographical union but also continued progression of valgus deformity Figure 1 Anteroposterior and lateral radiography showing a transverse distal tibial fracture with ankle valgus deformity, nine weeks after a free fibula flap Figure 4 Anteroposterior and lateral postoperative radiography following tibial osteotomy and Ilizarov frame correction Figure 2 Anteroposterior and lateral radiography, four weeks after fracture, showing callus formation but progression of valgus deformity despite being treated non-weight bearing in plaster plate was used to stabilise the ankle and substitute the missing lateral support from the fibula. At both surgical procedures, the bone was noted to be very soft so locking screws were used. He was treated partially weight bearing for six weeks. At follow-up, with regard to his deformity correction, he was complication free and able to mobilise normally (Fig 6). Discussion Stress fracture following a free fibula flap procedure is considered a rare complication. We believe that this 410 Ann R Coll Surg Engl 2015; 97:

3 Figure 6 Anteroposterior and lateral radiography, seven weeks after anterolateral plating Figure 5 Anteroposterior and lateral radiography, eight weeks following deformity correction, showing callus formation complication is neither expected nor mentioned in the consenting process. A literature review revealed 13 previously documented cases (Table 1) Conversely, it would appear that this is not common knowledge, with a recent paper claiming to be the first 16 while others have been unaware of previous reports. Each case presented with ipsilateral leg pain. In two of the cases, 13,16 fracture occurred during activity, indicating structural instability. The time from fibular excision to fracture varied: 9 patients presented within 6 months while the longest time from surgery to fracture was 16 months. The majority of cases were treated non-operatively, with none reporting the findings of their follow-up or radiography demonstrating healing. In the one other case that was treated operatively, a medial tibial plate was used. However, no follow-up radiography was provided. This did not appear to be the most mechanically sound way of treating this fracture/deformity. Instead, we believe it would be more appropriate to correct the valgus deformity and provide subsequent structural support, as was done in our case. While it was previously believed that the fibula was a static strut for the ankle joint, it is now known that it stabilises the ankle joint in dorsiflexion during the strike phase of gait, where it receives its greatest load. 18,19 Fibular resection therefore leaves a mobile distal fibula, which is unable to resist talar lateral force during weight bearing. 19 This talar force is responsible for the static loadbearing property of the fibula. 20 It has been shown previously that between 5% and 20% of weight bearing load is transmitted through the fibula As a result, excision of the fibula can lead to ankle instability 22 or deformity. 23 Nevertheless, the specific cause of ankle deformity and instability following fibulectomy is poorly understood and possibly multifactorial. 24 Nathan et al believed that adults are more likely to develop ankle pain than instability, with instability and deformity more prevalent in paediatric fibulectomies. 25 In a level II systematic review of free fibula flap complications, Ling and Peng found the following donor site morbidities: limited range of movement in the ankle (11.5%), chronic pain (6.5%), ankle instability (5.8%) and considerable gait abnormality (3.9%). 6 In addition to these, most subjects complained of transient pain, with an average time of 6.8 weeks until pain free ambulation. Of these complications, pain does appear to be the most commonly reported. Pacelli et al recognised as many as 40% of fibulectomy patients had chronic pain, 8 Tang et al noted 27% of patients had postoperative pain that eventually improved 26 and Zimmermann et al reported that recurrent pain was experienced by 23.7% of their patients. 27 Vail and Urbaniak noted that this activity related pain and discomfort actually increased considerably with time: at three months, 1.6% had ankle pain in comparison with 11.5% at five years. 23 There was no uniform way of measuring chronic pain in these papers. Despite the undetermined aetiology of ankle deformity and pain in these papers, it is apparent that fibulectomies were a major contributing factor to the pain and subsequent tibial fracture in each of the cases in Table 1. Given the uncommonness of this complication, it is difficult to extrapolate a method of prevention. However, it is Ann R Coll Surg Engl 2015; 97:

4 Table 1 Summary of reported cases in the literature Author / year Age / sex Diagnosis of fracture Significant co-morbidities Surgical cause of defect requiring free fibula graft Vascularised? FWB following fibulectomy at: Treatment Follow-up Acknowledgement of other papers Han, Specifics not presented None Ivey, 62 F 4 months Nil reported Atrophic non-union of the humerus Yes N/A Plaster (long leg) N/A None Emery, 68 F 4 months Nil reported Spondylotic myelopathy (cervical 65 F 9 months Oestrogen therapy Kyphosis (cervical 31 F 11 months Nil reported Kyphosis (lumbar osteotomy) 41 M 16 months Nil reported Paget s disease of bone (spondylectomy) 55 F 10 weeks Oestrogen therapy, smoker Kyphosis (cervical Westesson, 62 F 11 months Diabetes Oral SCC Removable splint 12 months Han Removable brace 36 months None Rest 21 months No 3 days Rest 3 months No 3 days Splint, cane 6 months Yes N/A Plaster None Emery, Ivey Hollow, 50 M 5 months (after jump/fall) Nil reported Oral SCC Yes 10 days Plaster 8 weeks None Wolf, 82 F 6 months Nil reported Oral SCC (alveolar ridge resection) Yes N/A Plaster, then brace 5 months Han, Emery, Ivey Westesson Pacifico, 46 M 2 months (after long walk) Nil reported Oral SCC õ osteoradionecrosis Kabadaya, 49 F 6 weeks Nil reported Oral SCC Yes N/A Plaster None Emery, Ivey, Westesson Yes 5 weeks Medial plate None Hollow Lison, 65 F 10 weeks Smoker Osteoradionecrosis Present paper 67 M 9 weeks Ex-smoker (stopped 30 years earlier) Mandibular adenocarcinoma Yes 7 days Removable splint None Emery, Ivey, Westesson, Wolf, Kabadaya, Yes 7 days Tibial osteotomy and circular frame, then anterolateral plate 9 months after fixation All of the above FWB = fully weight bearing; N/A = not applicable; = weight bearing as tolerated; SCC = squamous cell carcinoma 412 Ann R Coll Surg Engl 2015; 97:

5 pertinent to suggest the possibility of underreporting of this complication, especially given the high prevalence of functional pain in the above mentioned papers. Nevertheless, ascertaining the incidence of this complication is further problematic owing to the low number of free fibula flaps performed in specialist units. In Munich, 104 were performed over a 10-year period 3 while Ling and Peng s systematic review looked at 2,534 flaps, 6 with the biggest study containing 250 flaps over a 10-year period. 28 Is this complication clinically relevant? We believe so. Lee et al noticed a change in ankle load transmission as well as gait abnormalities in their follow-up. 29 It would make sense that structural variation with resultant functional modification would be a potential cause for ankle deformity and fracture. At this point, however, this is speculation. In our case, we believed that non-operative management would have been inappropriate. Without addressing the structural problem that caused the fracture and deformity, it would be likely to either refracture once healed or continue to progress into valgus. Similarly, if a lateral compression force, resultant from the lack of a fibula diaphysis, caused fracture and valgus deformity, it would make sense that a lateral strut would prevent this compression force. This is why we believe our surgical treatment, by an anterolateral tibial plate, makes sense functionally. Conclusions We believe that this complication should be consented for as it is a significant morbidity with functional implications. If surgeons are aware of it as a complication, it may increase the number of reports, giving further insight into which patients are at risk of fracture. Does the level of mobility of the patient or the extent of his or her concurrent disease play a significant factor? These are questions that cannot be answered at this point but that should definitely be revisited in time. 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