ABSTRACT
BACKGROUND: Defining the injury-force mechanism in tibial plateau fractures (TPFs) could help define implant type and position, as well as soft tissues at risk. The aim of this study was to provide an analysis of injury-force-mechanisms in TPFs, including axial rotation. METHODS: The injury-force mechanism was determined for 203 fractures that presented over a period of 3.5 years. Fractures were classified as flexion-varus/valgus/neutral or (hyper)-extension-varus/valgus/neutral by observing articular depression area on CT/MRI. Fractures were subclassified into rotation-neutral, internal- or external-rotation according to the Gerdy-tibial-tuberosity-surgical-epicondylar-axis (GTT-SEA) angle. Soft-tissue injury was documented if MRI was performed. RESULTS: Flexion-valgus was the most common injury-force mechanism (n = 85, 41.9%), followed by extension-valgus (n = 57, 28.1%). Other mechanisms were less common (9.4% extension-varus, 5.9% flexion-neutral, 4.9% flexion-varus, 3.9% hyperextension-valgus, 3.4% extension-neutral and 2.5% hyperextension-varus). The GTT-SEA angle could be measured in 194 (95.6%) of 203 classified patients, revealing internal rotation in 83 (42.8%) and external rotation in 53 (27.3%). No significant difference was found between injury-force mechanism type and axial rotation group (P = 0.964) or extent of rotation (H(8) = 7.116, P = 0.524). Only 41 (21.1%) of 194 fully classified fractures underwent MRI, all revealing soft-tissue injury to some extent. High-grade posterolateral injuries occurred mainly in rotated TPF. CONCLUSION: Our results describe the common forms of axial rotation present in TPF and explore their association with injury-force mechanism and soft-tissue injury. Applying the injury-force mechanism patterns and addressing rotational forces could, together with preoperative MRI and intra-operative stability assessment, help determine the need to surgically address associated soft-tissue injury.
ABSTRACT
OBJECTIVES: Rotated tibial plateau fractures (TPF) frequently involve multiple planes of movement, yet current presurgical assessment methods do not account for tibiofemoral axial rotation. This study introduces and validates a simple tool to measure rotation-the Gerdy-Tibial-Tuberosity-Surgical-Epicondylar-Axis (GTT-SEA) angle. METHODS: Forty-seven preoperative 2D CT from a TPF database at a tertiary trauma center were retrieved, and 3D models reconstructed. Three observers made repeated 2D and 3D measurements of the GTT-SEA angle, spaced 4 weeks apart, for 20 patients. Inter- and intra-observer agreement and 2D-3D correlation were calculated. A reference angle was defined from non-operated patients, to classify 28 patients with MRI into neutral, external rotation, and internal rotation groups. The classification agreement and soft tissue involvement between groups were analyzed. RESULTS: Mean 2D GTT-SEA angle was 17.65 ± 2.36° in non-operated patients, and 13.86 ± 3.90° in operated patients. 3D GTT-SEA angle was 18.92 ± 4.53° in non-operated patients, and 14.76 ± 6.03° in operated patients. 2D-3D correlation was moderate to good (ICC 0.64 ~ 0.83). Two-dimensional (ICC 0.70) and 3D (ICC 0.55) inter-observer agreements were moderate; 2D (ICC 0.82 ~ 0.88) and 3D (ICC 0.76 ~ 0.95) intra-observer agreements were good to excellent. Rotation classification agreement was slight (kappa 0.17) for 2D and good (kappa 0.76) for 3D. More popliteofibular ligament injury was detected in rotated knees (p = 0.016). CONCLUSIONS: The GTT-SEA angle offers simple, accessible, yet reliable measurement of tibiofemoral axial rotation. Though a true reference range remains to be determined, this tool adds valuable information to existing TPF classifications, potentially allowing assessment of soft tissue involvement in TPF. CLINICAL RELEVANCE STATEMENT: The GTT-SEA angle will benefit patients who sustain tibial plateau fractures, by allowing physicians to more accurately measure and plan for the injury in 3D, and raising suspicion for otherwise undetected soft tissue injuries, which can impact operative outcomes. KEY POINTS: ⢠Traumatic fractures of the tibial plateau may contain rotation-induced soft tissue injuries. ⢠A new tool to measure axial rotation between the femur and tibia was found to have moderate to excellent inter- and intra-rater reliability. ⢠The tool may have potential in predicting soft tissue injury and assisting with the decision to receive MRI.