Der posterolaterale Zugang – eine Alternative zur geschlossenen anterior-posterioren Schraubenosteosynthese bei komplexen Sprunggelenkfrakturen

Zusammenfassung

Hintergrund: Das dislozierte posterolaterale Fragment der distalen Tibia ist das Schlüsselfragment bei der erfolgreichen Reposition komplexer Sprunggelenkfrakturen. Ziel dieser Studie war der Vergleich des klinischen Ergebnisses nach Stabilisierung des dislozierten posterolateralen Tibiakantenfragments über eine indirekte Reposition und gedeckte anterior-posteriore Schraubenosteosynthese oder durch direkte Reposition über einen offenen posterolateralen Zugang und Plattenosteosynthese. Patienten/Material und Methoden: In einer prospektiven Studie zwischen 01/2010 und 12/2012 wurden alle Patienten mit geschlossener Sprunggelenkfraktur mit disloziertem posterolateralem Fragment als Monotrauma eingeschlossen. 12 Monate postoperativ erfolgte eine klinische und radiologische Nachuntersuchung unter Anwendung des „Ankle Fracture Scoring Systems“ (AFSS). Ergebnisse: Bei 11 Patienten (Durchschnittsalter 51,6 ± 2,6 Jahre, Größe des Tibiafragments 42,1 ± 2,5 %) wurde die offene Fragmentfixation über einen posterolateralen Zugang durchgeführt. Zwei dieser Patienten zeigten eine prolongierte postoperative Wundheilung. In der Vergleichsgruppe wurden 12 Patienten mit gedeckter anterior-posteriorer Schraubenosteosynthese behandelt (Durchschnittsalter 59,5 ± 6,7 Jahre, Größe des Tibiafragments 45,9 ± 1,5 %). Einer dieser Patienten erlitt eine inkomplette Läsion des N. peronaeus superficialis. Die postoperative radiologische Beurteilung im CT ergab eine signifikant geringere verbliebene Stufe der tibialen Gelenkfläche nach offener Reposition über posterolateralen Zugang (0,60 ± 0,20 mm) im Vergleich zur gedeckten anterior-posterioren Verschraubung (1,03 ± 0,08 mm; p < 0,05). Die Auswertung des AFSS ergab einen signifikant höheren Score von 97,4 ± 6,4 in der Gruppe mit posterolateralem Zugang im Vergleich zu einem Score von 74,4 ± 12,1 (p < 0,05) in der Gruppe mit anterior-posteriorer Verschraubung. Schlussfolgerung: Im Vergleich zur gedeckten indirekten anterior-posterioren Schraubenosteosynthese zeigten die Ergebnisse dieser Studie eine deutlich bessere Frakturreposition und ein signifikant besseres klinisch-funktionelles Ergebnis 12 Monate nach direkter Osteosynthese des dislozierten Hinterkantenfragments über einen posterolateralen Zugang und ermutigen dazu, die offene Reposition und interne Fixation des dislozierten Tibiahinterkantenfragments über einen posterolateralen Zugang als sinnvolle Alternative zum Standardverfahren der gedeckten anterior-posterioren Schraubenosteosynthese anzuwenden.

Abstract

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.

Schlüsselwörter

Sprunggelenkfraktur - disloziertes posterolaterales Tibiakantenfragment - posterolateraler Zugang - anterior-posteriore Schraubenosteosynthese

Key words

ankle fracture - dislocated posterolateral tibia fragment - posterolateral approach - anterior-posterior screw fixation

^* C. von Rüden und S. Hackl haben zu gleichen Teilen zum Manuskript beigetragen.

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