Delayed surgical reconstruction of adult ankle malunion by supramalleolar osteotomy

INTRODUCTION

Ankle fractures are a common cause of morbidity and disability following skeletal trauma. Ankle fractures are among the commonest of skeletal injuries with a reported incidence of 125/100,000/year.^1-6 Malunion is equally common with a reported occurrence of up to 68% in some studies.¹ The main objective of treating ankle malunion is to restore the anatomy of the ankle mortise, fibula length and orientation. Talar shift and tilt are normally caused by fibula shortening and malrotation.² Ankle fracture malunions are an important cause of chronic pain, functional impairment and ultimately post traumatic arthrosis.¹ In the young and working population this leads to loss of many man-hours because of the importance of the ankle joint in mobility.

Modes of treatment of ankle malunions are varied and controversial. Apparently stable fractures might in the course of treatment malalign and eventually heal as malunion. Malunion rates of upto 68% are reported in the literature.^1,7 Where resources are scarce and in areas where conservative management predominates it is essential to have some extra corrective skills for malunion instead of routinely offering patients arthrodesis of pains management.

The results of this study compare favourably with many other studies.^3,7-10 Its currently believed just like Weber (1972) that the fibula remains the main key pillar in the ankle joint biomechanics. That anatomic restoration of the ankle mortise is possible only by reinstatement of the fibular length and rotation.² The purpose of this study is to report a cheap and reproducible technic to the trauma surgeons involved in the management of these injuries.

METHODS

A retrospective of review adult patients with old ankle malunion initially treated conservatively by casting were included. The patients were treated by surgical reconstruction by the author at selected private hospitals in Nairobi, Kenya between January 2015 and December 2017. The principal author was involved in the surgery of all the cases.

Data was collected using case reviews, radiographic findings, history and clinical examination. Pre-operatively, plain antero-posterior and lateral X-rays were done for both ankle joints. Where malunion was unclear on plain radiographs CT-Scans were done for the affected ankle joint. Fibula length and mal-rotation were studied and deficit corrected on the planning images using the technique of weber.²

Surgical technique

Informed consent was obtained from all patients after explaining the procedure. All the procedures were performed under spinal anesthesia. An intravenous second generation cephalosporin was given during induction of the anesthesia before the application of tourniquet. The surgery was conducted under intermittent intraoperative Fluoroscopy. In all the cases supra malleoli fibula osteotomy and one stage lengthening and correction of the mal-rotation was done. Tricortical bone graft was harvested from the ipsilateral tibial plafond and fixation done by 3.5 mm dynamic compression plates (Synthes). Medial malleolus osteotomy was always done first if mal-aligned then followed by correction using long 4.0 mm lag screws (synthes). The medial malleolus being done first facilitated easier eventual mobilization of the talus. Any other additional osteotomy depended on the images and intraoperative findings. In Weber type C sometimes a syndesmotic screw was fixed (Figure 1 and 2 A-D).

Follow up

Postoperatively, initially an incomplete back slab Dynacast was applied for 2 weeks. There after a complete cast was applied for 4 weeks. At 6-8 weeks any syndesmotic screws were removed and minimal partial weight bearing was commenced at 8 weeks. Normally at 3 months full weight bearing was commenced as dictated by the healing on check X-rays.

There after repeat X-rays were done at 4 months and 6 months of follow until union was achieved. The implants were removed any time after 18 months. All the patients were evaluated by clinical examination, the functional Olerud-Molander ankle score (OMAS) and the final X-rays.

RESULTS

In total only 21 patients fulfilled the criterion for inclusion into this study. Fourteen female and seven male patients were recruited into the study. Ages ranged from 20 to 50 years. Majority of the (14) patients were aged between 40- 50 years and of these 10 were females. The durations from time of the fracture to malunion varied from 6 months to 3 years (Table 1). Accurate evaluation is essential for good outcome. When in doubt CT scan of the ankle was done for further analysis (Figure 2D). In one patient with chronic ankle pains at one year post injury the X-rays (Figure 1) showed only subtle changes (Figure 2A-C). But a CT scan of the same patient was more revealling of the malunion (Figure 2D).

It is reasonable to compare the normal side to the painful side because of individual variations. This patient was managed by one stage fibula lengthening and bone grafting. She was asymptomatic on final follow up.

The duration between the primary injury and reconstruction ranged from months to years but the rediolgical results were excellent (Figure 1). The average duration of surgery was 2 hours, hospital stay 3 days and then casting was done for 4 weeks. Partial weight bearing commenced after 4 weeks and full weight bearing when union was complete.

In all cases patients were full weight bearing by 3 months. There was no long term loss of reduction. The main outcome evaluation measurement instrument was the Olerud & Molander score (OMAS).⁵ The functional outmes was excellent 12 patients post surgery (Table 2, Figures 3 A-F). Despite the small numbers most patients had good to excellent results. The 2 patients with fair results were obese and this could have contributed to their fair functioonal results but their X-rays revealed anatomical alignment (Figure 4). In this study no patient had poor results. A further detailed analysis of the OMAS score is shown on Table 3.

DISCUSSION

Ankle fractures are a common injury that results in significant morbidity if complicated by malunion. The reported incidence globally is around 125/100,000/year.^5,6 Studies show that with good early treatment of unstable fractures good to excellent results vary from 60-90 percent from different series.^5,6,8,11,12

Late presentations of ankle fractures are not infrequent in the developing world. This could be attributed to scarcity of health facilities, specialists and lack of finances. I am not aware of any study in the developing world describing a corrective technique for ankle malunion using fibula osteotomy and lengthening. It is essential that specialists in this region have skills to manage these common and disabling injuries with good outcomes.

Where studies have been done the incidence of ankle fracture malunion is 5-68%.^1-3 The wide variation is because of the large variation in fracture types and treatment modalities. Giannini et al in their recent review of 22 patients found only 2 with poor results.⁷ The correction of malalignment was maintained in there review of 20 cases in 2012, and they also found that even in delayed fractures treatment was as quick and good as in fresh fractures.⁹ In one of the largest studies involving 1822 patients, and 5 year follow up, the authors concluded that in fresh fractures with optimal surgical reduction and internal fixation 79.3% had good to excellent results.⁵ In a study of the functional outcome of ankle fracture fixation after 5 years utilizing the Olerud and Molander score by Shah reported 62.0% of patients attained the pre-injury level of physical activities.¹ Half (50.7%) of their patients still complained of some sort of pain. In our case slightly less than half complained of some pain in strained conditions (Table 3). 63% of their patients still complained of stiffness as compared to slightly less the half in our cases. Fresh ankle fractures surgical fixation does not yield 100% good results. Studies show that excellent results are in the region of 70% after optimal reduction and fixation.^1,5 The results of late correction are nearly similar to fresh cases.

CONCLUSION

Supramalleolar osteotomy and fibula lengtheninig for delayed ankle reconstruction is a reliable mode of treatment of ankle malunion after conservative fractures management.

ACKNOWLEDGEMENTS

The hospitals for allowing access to the patients records and publication.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

REFERENCES

1. 1. Shah N, Sundaram R, Valusamy A, Brathwonte I. Five-year functional outcome analysis of ankle fracture fixation. Injury. 2007;38:1308-12.
2. 2. Weber B, Simpson L. Corrective Lengthening osteotomy of the fibula. Clin Orthop Related Res. 1985;199:61-7.
3. 3. Henderson W, Lau J. Reconstruction of failed ankle fractures. Foot Ankle Clin N Am. 2006;1:51-60.
4. 4. Gregory D, Dickos M, Jason D, Rober H. Choplin M, Weber M. Normal tibio fibular relationship at the syndesmosis on axial CT Imaging. Orthop Trauma. 2012;2:26.
5. 5. Joerd A, Michel P, Gino M, Beat H, Nierk Van Dijk. Long-term outcome after 1822 operatively treated ankle fracture. A systematic review of the literature. Injury. 2011;42:119-27.
6. 6. Makwana N, Bohwal B, Harper W, Hui A. Conservative versus operative treatment for displaced ankle fractures in patients over 55 years of age:a prospective randomized study. J Bone Joint Surg. 2001;83:523-9.
7. 7. Sandio G, Cesare F, Francesco A. Surgical treatment of post-traumatic malalignment of the ankle. Injury. 2010:41:1208-11.
8. 8. Khan WS, Malik AA, Aggarwal M, Dalal R. Delayed open reduction and internal fixation of a neglected fracture dislocation of the ankle. Int J Clin Pract. 2007;61:594-5.
9. 9. Serder T, Morgan S, David JH. Fixing the almost healed ankle fracture, is surgery reduction and complication rate different from acute open reduction and internal fixation? Current Orthop Pract. 2012;23:1.
10. 10. Fogel GR, Morrey BF. Delayed open reduction and fixation of ankle fractures. Clin Orthop Relat Res. 1987;215:187-95.
11. 11. Offierski CM, Graham JD, Hall JH, Harris WR, Schatzker JL. Late revision of fibular malunion in ankle fractures. Clin Orthop Relat Res. 1982;171:145-9.
12. 12. Olerud C, Molander H. A scoring scale for symptom evaluation after ankle fracture. Arch orthop Trauma Surg. 1984;103:190-4.