Prospective study of outcome of trimalleolar ankle fractures

INTRODUCTION

Ankle is one of the most commonly injured joint among the lower limb trauma. As with all intraarticular fractures trimalleolar fractures also require anatomical reduction and stable internal fixation. Posterior malleolus fractures are involved in 7-44% of rotational ankle fractures.¹ Surgical fixation has been the recommended course of treatment in fractures affecting more than 25% of the articular.^2,3 Ankle fractures are widely classified based on Lauge Hansen and Danis Weber classification system. The clinical significance of posterior malleolar (PM) fracture morphology and pattern however has not yet been determined.³

The posterior inferior tibiofibular ligament (PITFL) may tear as a result of the ankle fracture's typical rotational injury mechanism or it may avulse the posterior malleolar fragment. Research has shown the value of even minor posterior malleolar fragments for ankle stability and surgical indications have increased. Typically buttress plates are used in a posterolateral (PL) approach to fix posterior malleolar fragments or percutaneous anterior to posterior (AP) screws. Fixation with AP screws requires ligamentotaxis of the posterior inferior tibiofibular ligament and reduction of the fibula along with reduction of the posterior malleolus whereas fixation with a posterolateral approach allows direct reduction of the fracture fragment. The majority of AO type B injuries are treated with buttress plating rather than screw fixation. We believed that posterolateral buttress plating may have advantages over percutaneous AP screw fixation. Studies have shown that ankle fractures involving the posterior malleolus have worse outcomes than ankle fractures without posterior malleolar involvement. Purpose of the study is to assess the functional and radiological outcome along with results of trimalleolar fracture treated by different method such as TBW/CC screw fixation for medial malleolus and ORIF with plate and screws for lateral malleolus and posterior malleolus fracture to obtain stable ankle joint.

CASE SERIES

This is prospective study performed in our tertiary centre between 2020 September and May 2022. 15 patients with rotational type of ankle fracture with concomitant posterior malleolus fracture were considered and confirmed with radiographic evaluation. Study group of 15 patients included 9 male and 6 female patients. Inclusion criteria 18 years and older with closed rotational type of ankle fracture with posterior malleolus fracture. Exclusion criteria were polytrauma patients associated with distal tibial pilon fracture and open fractures.

Patient in lateral position, posterior-lateral approach gives direct access to posterior malleolar fragment between achilles tendon and fibula. Make 10-15 cm longitudinal incision between fibula and achilles tendon. Skin and subcutaneous tissue to be dissected care to be taken not to damage sural nerve. Peroneal muscles to be retracted laterally which exposes the Volkmann fragment. Reduction of fragment anatomically and articular step off should be reduced precisely and supported with buttress plate and screws. Once the fragment has been fixed peroneal muscles to be retracted medially to expose fibula with lateral malleolus fracture, plated through the same incision and allow peroneal muscles to return to its normal anatomical position covering the plate. Deep fascia along with subcutaneous tissue and skin was closed. Medial malleoli fractures are fixed last with CC screw/tension band wiring.

Postoperative period and follow up

The duration of stay in hospital was 5 days. Patient were put in slab for 3 weeks. Suture removal was done after 15 days. Range of motion exercises were started with non-weight bearing mobilization. Partial weight bearing was started at 6 weeks and full weight bearing by 12 weeks. Patients were called for follow up at 2 weeks, 6 weeks, 3 months, 6 months and 12 months post operatively follow up assessment was done with help of Olerud and Molendar scoring system for functional assessment and Kristenson’s criteria for radiological outcome.

Results

Majority of our patients had good and excellent functional outcomes and were able to return to their activities as similar to Hong et al.¹⁰ Almost all the fractures united in 13 weeks with range between 11-20 weeks. Delayed union seen in 2 of our patients. Functionally excellent outcome was seen in 5 patients followed by 6 patients had good outcome, fair in 3 patients and poor in 1 patient. Kristenson’s criteria were used to assess the radiographic outcome. Radiological outcomes were similar to Khandelwal et al with poor outcome in 2 patients.¹¹ Ankle range of movements was regained in all patients except two. Complications such as superficial infection was noted in 2 out of 15 patients which corelated with fact of delayed union. Infection was treated with intravenous antibiotics. One patient developed post operative stiffness which was managed by physiotherapy.

A score of 90-100 – excellent, 70-89 – good, 50-69 – fair, and less than 50 – poor

DISCUSSION

Study population consisted of patient aged between 38-76 years old. Road traffic accidents (RTA) was common mode of injury followed by fall. 60% were males and 40% were females with predominant right-side injury. Supination external rotation type of injury was most common mode of injury in our study as comparable to study by Weening et al.⁴

Riede et al in his study showed that if posterior malleolus is displaced that would result in increased damage to remanent cartilage and lead to posttraumatic arthritis. Multiple studies consider posterior malleolar fixation would result in better outcome.^5,6 Hence we fixed posterior malleolus with buttress plate to avoid long-term complications which may need further follow up. Gardner et al compared posterior malleolar fixation with syndesmotic fixation in a pronation-external rotation 4 model.⁷ They found 70% restoration of good ankle function with posterior malleolar fixation versus 40% with syndesmotic fixation. Posterior malleolar fixation was equivalent to fixation with syndesmotic screws or combined fixation. We have used posterolateral approach which was similar to the study Talbot et al.⁸ Lateral malleolus was fixed with plate and screw while medial malleolus was fixed with 4 mm CC screw/TBW. We have not used syndesmotic screw as Kortekangas et al showed no difference in clinical and radiological out come after 4 years follow up.⁹

Majority of our patients had good and excellent functional outcomes and were able to return to there activities as similar to Hong et al.¹⁰ Almost all the fractures united in 13 weeks with range between 11-20 weeks. Delayed union seen in 2 of our patients. Functionally excellent outcome was seen in 5 patients followed by 6 patients had good outcome, fair in 3 patients and poor in 1 patient. Kristensons criteria was used to assess the radiographic outcome. Radiological outcomes was similar to Khandelwal et al with poor outcome in 2 patients.¹¹ Ankle range of movements was regained in all patients except two. Complications such as superficial infection was noted in 2 out of 15 patients which corelated with fact of delayed union. Infection was treated with intravenous antibiotics. One patient developed post operative stiffness which was managed by physiotherapy.

Anatomical reduction with stable fixation of every component of fracture is probably more important than the way of fixation. It is accepted that anatomical reduction is the goal of ORIF of every fracture. Can be better achieved with a posterior approach and posterior buttress plate fixation, even in cases with poor bone quality. In addition, excellent stability was achieved and allowed better function. We do know that fractures with posterior malleolar involvement do worse than similar fractures without posterior malleolar involvement. Instability rendered in a posterior malleolar fracture is in fact an important variable in the outcome of patients. The results of these studies would lead to the conclusion that even small posterior malleolar fractures should be repaired in ankle fractures with syndesmotic disruption The two clinically relevant problems in treatment of trimalleolar fracture-dislocations are the non-anatomical reduction and the relatively unstable primary fixation of the posterior malleolus. By open reduction through a posterolateral approach and stabilization of the fragment with a dorsal buttress plate, anatomical reduction was significantly improved with better primary stability. Langenhuijsen found that it was not the size of the fragment that affected outcome rather, whether a congruent reduction was obtained even in posterior malleolar fractures making up only 10% of the joint surface. There is also improved biomechanical stability of the fracture in fixation with a buttress plate that can resist shear. As these are the main goals of surgical treatment of fractures, this surgical approach seems currently preferable. The complication rate was no higher than that documented for currently recommended techniques. However, whether better reduction with the method presented here leads to less clinically relevant osteoarthritis of the ankle remains to be established by long term study.

CONCLUSION

Posterior malleolar fixation along with medial and lateral malleolus fixation will lead to better functional and radiological results. Trimalleolar fracture with stable anatomical fixation would result in early rehabilitation and return to activity. Development of long-term complications such as arthritis needs further follow up and evaluation.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

REFERENCES

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