Schatzker II tibial plateau fractures: Anatomically precontoured 3.5 mm locking compression plates allow for improved patient outcome

AIMS AND OBJECTIVES: In the operative treatment of split depression factures to the lateral tibial plateau, the reconstruction of the depressed joint surface is eagerly sought after. The subchondral bony defect often requires bone grafting or bone graft substitutes. At least equally important is the achievement of an internal fixation that provides the greatest possible support for the fragile joint surface fragments. The design of the anatomically precontoured locking compression plates features a higher number of locking screws underneath the joint surface and permits the screw placement closer to the subchondral zone compared to conventional plates. Whether the altered design results in better patient outcome is analysed in this study. MATERIALS AND METHODS: Our databank was searched for Schatzker II fractures from 2012 until 2015. Patients that underwent open reduction and internal fixation with anatomically precontoured 3.5 mm locking compression plates (A) or conventional 4,5 mm L-shaped locking compression plates and screws (B) were included and retrospectively evaluated. CT-scans, radiographs in two planes and in full length standing mode, if available, were analysed. Details of the operative procedures and secondary events were determined. Objective outcome parameters were collected from the patient records, subjective outcome parameters were assessed in a survey and WOMAC as well as Rasmussen functional knee scores were calculated. RESULTS: A total of 36 patients were included (A=20, B=16). The mean patient age, the ratio male to female and the mean follow up were comparable. CT-scans revealed an equal mean size of the depressed joint surface (A: 23.7 x 25.3 mm; B: 23.9 x 24.0 mm) and maximal depression depth (11.2 and 11.8 mm). The duration of the operation, the frequency of utilizing bone grafts or bone graft substitutes and of lateral meniscus repair as well as the rate of subsequent implant removal were also comparable. In the early postoperative controls, the radiological assessment according to Rasmussen revealed a mean score of 9.1 (A) and of 8.5 (B). During follow up, the mean score decreased to 8.1 and 6.7 for A and B, respectively. This difference was statistically significant (p<0.05). A valgus deviation was more often observed in group B. Both, the WOMAC and the Rasmussen functional knee score revealed lower mean values for group B in the final evaluation. CONCLUSION: The progressive decrease of the Rasmussen radiological score for the conventional 4,5 mm L-shaped locking compression plates and screws was predominantly due to a secondary loss of reduction and an increasing valgus deviation. The altered design of the anatomically precontoured 3.5 mm locking compression plate seems to prevent more sufficiently the reduced joint surface fragments from sintering over time. The anatomically precontoured 3.5 mm locking compression plate allows for improved patient outcome and should closely be considered for internal fixation of split depression fractures to the lateral tibial plateau.