[The Postero-Lateral Approach--An Alternative to Closed Anterior-Posterior Screw Fixation of a Dislocated Postero-Lateral Fragment of the Distal Tibia in Complex Ankle Fractures].

BACKGROUND

The dislocated posterolateral fragment of the distal tibia is considered as a key fragment for the successful reduction of comminuted ankle fractures. The reduction of this fragment can either be achieved indirectly by joint reduction using the technique of closed anterior-posterior screw fixation, or directly using the open posterolateral approach followed by plate fixation. The aim of this study was to compare the outcome after stabilization of the dislocated posterolateral tibia fragment using either closed reduction and screw fixation, or open reduction and plate fixation via the posterolateral approach in complex ankle fractures.

PATIENTS/MATERIAL AND METHODS: In a prospective study between 01/2010 and 12/2012, all mono-injured patients with closed ankle fractures and dislocated posterolateral tibia fragments were assessed 12 months after osteosynthesis. Parameters included: size of the posterolateral tibia fragment relative to the tibial joint surface (CT scan, in %) as an indicator of injury severity, unreduced area of tibial joint surface postoperatively, treatment outcome assessed by using the "Ankle Fracture Scoring System" (AFSS), as well as epidemiological data and duration of the initial hospital treatment.

RESULTS

In 11 patients (10 female, 1 male; age 51.6 ± 2.6 years [mean ± SEM], size of tibia fragment 42.1 ± 2.5 %) the fragment fixation was performed using a posterolateral approach. Impaired postoperative wound healing occurred in 2 patients of this group. In the comparison group, 12 patients were treated using the technique of closed anterior-posterior screw fixation (10 female, 2 male; age 59.5 ± 6.7 years, size of tibia fragment 45.9 ± 1.5 %). One patient of this group suffered an incomplete lesion of the superficial peroneal nerve. Radiological evaluation of the joint surface using CT scan imaging demonstrated significantly less dislocation of the tibial joint surface following the open posterolateral approach (0.60 ± 0.20 mm) compared to the closed anterior-posterior screw fixation (1.03 ± 0.08 mm; p < 0.05). Assessment of the treatment outcome using the AFSS demonstrated a significantly higher score of 97.4 ± 6.4 in the group with a posterolateral approach compared to a score of 74.4 ± 12.1 (p < 0.05) in the group with an anterior-posterior screw fixation.

CONCLUSION

In comparison to the anterior-posterior screw fixation, open reduction and fixation of the dislocated, posterolateral key fragment of the distal tibia using a posterolateral approach resulted in a more accurate fracture reduction and significantly better functional outcome 12 months after surgery. In addition, no increased rate of postoperative complications, or extended hospital stay was observed but there was less severe post-traumatic joint arthritis. The results of this study suggest that in complex ankle factures the open fixation of the dislocated posterolateral fragment is recommended as an alternative surgical procedure and may be beneficial for both clinical and radiological long-term outcomes.