Small fragment screws vs. plate osteosynthesis in condylar head fractures. A comparison of functional results based on MRI and axiography

Aims: This prospective study evaluates the outcome after osteosynthesis of condylar head fractures using 1.7 mm small fragment screws (2/2000 ff), which were selected according to a previous biomechanical trial to optimize condylar head traumatology. Clinical and functional results were compared to a group of fractures fixed mainly by mini- and microplates (1993-2000) and to a control group after conservative therapy with early functional training. Patients and methods: Functional values (axiography and MRI) regarding loss of vertical height, disk mobility, protrusive and translatory movements were assessed (a) in 34 of 83 condylar head fractures (groups V and VI according to Spiessl and Schroll, 22/69 subjects) managed by osteosynthesis with 1.7-mm small fragment screws (KFS), (b) a reference group (43/84 subjects) fixed mainly by mini- or microplates (PLO), comprising 56 of 101 fractures (1993-2000), and (c) 16 condylar head fractures after conservative therapy with early functional training (KT) as a control. Results: In cases of small fragment screws, loss of vertical height (0.3 mm) was significantly reduced (p<0.01) in comparison to PLO (1.6 mm) and KT (6.9 mm). Disk mobility in KFS reached 90% of the non-fractured sides (NFS), thus clearly superior (p<0.01) to PLO (63% of NFS) and KT (40% of NFS). Translatory movements after KFS showed better results, too (p<0.05), with mediotrusion 84% and protrusion 80% of NFS. After PLO, mediotrusion was 62%, protrusion 71% of NFS, whereas KT showed only 53% (mediotrusion) and 56% (protrusion) of NFS. High-grade limitations of translatory movements presented in about 30% after PLO and <10% in KFS (p<0.01). Fragment displacements were found in <5% after small fragment screws, and in the plate osteosynthesis group in 15% (p<0.01). Conclusions: Due to better stability and reduced articular scarification osteosynthesis with 1.7-mm small fragment screws in condylar head fractures showed clearly superior functional results compared to mini- and microplates, and to conservative therapy.