Taylor Spatial Frame Behavior in High Tibial Osteotomies: A Clinical–Mechanical Study

The introduction of Taylor Spatial Frame (TSF) in clinical practice allows for unique capabilities in long bone deformity corrections; however, a comprehensive understanding of its mechanical characteristics and their impact on callus formation at the osteotomy site is still unclear. The current study is concerned with the clinical application of TSF in high tibial osteotomy (HTO) and the mechanical testing of this device. Fifty-five (55) patients with symptomatic medial compartment knee osteoarthritis and varus deformity underwent open-wedge HTO with the use of TSF and were prospectively monitored with regard to callus formation pattern at the site of osteotomy. Clinical evaluation revealed that the callus formation pattern was eccentric in all patients. In addition, the experimental results from mechanical testing of a clinically relevant TSF configuration indicate, that vertical deflection of the upper bone part during weight-bearing is accompanied by a rotation of the bone axis, which acts in the same direction to the rotation applied during the clinical correction process. The complementary contributions of the deformity correction process and the mechanical response of the TSF under compressive loads, lead to asymmetric gap closure, which promotes the eccentric callus formation in the osteotomy site. The study provides useful information for clinical decision-making regarding callus formation process when TSF external fixator is applied in HTOs.