Introduction
Nonunion is a common complication after tibial shaft fractures. It occurs in around 7.6% of patients [1]. Nonunion is currently diagnosed based on infrequent radiographs, but due to delay in bone mineralization, it can take months before it is possible to diagnose healing delays. Timelier methods to detect nonunions are required. Since it is known that gait improves during fracture healing in patients with union [2], we hypothesized that the healing outcome can be predicted based on gait already during the early healing process.
Research Question
Can gait analyses be used to predict nonunion throughout the healing phase of tibial shaft fractures?
Methods
Patients with a recent surgically treated tibial shaft fracture were included in this study and were assessed shortly after surgery and during multiple outpatient visits. On each visit, patients walked 10m in a straight line while wearing instrumented insoles (OpenGO insoles, Moticon GmbH, Munich, Germany). These insoles contain 16 pressure sensors, a triaxial accelerometer and a triaxial gyroscope. The insole data were used to calculate maximal force, pressure distribution underneath several parts of the feet, centre of pressure, temporal parameters, maximal vertical acceleration, maximal velocity around the mediolateral axis, and asymmetry of these parameters. In addition, patients filled out questionnaires with patient-reported outcome measures during each visit. Six months after surgery, radiographs were used to assess whether the fracture had healed.
Results
Seven out of 18 longitudinally assessed patients (union: 44 ± 15 years; nonunion: 51 ± 21 years) were diagnosed with nonunion. Within the first days after surgery, only three out of the 33 gait parameters were significantly different between the groups. At six weeks, 16 out of 33 gait parameters were significantly different between patients with and without union. At three months, only five gait parameters were significantly different between the groups. At six months, nine gait parameters were significantly different between the groups (Figure 1). These differences were most pronounced in the temporal and pressure distribution parameters, as well as the maximal angular velocity. Patient-reported outcome measures only showed group differences six months after surgery.Discussion
Gait analysis outperforms the use of radiographs or patient-reported outcome measures in the detection of patients with a particularly high risk of tibial nonunion. This is, however, only true when the nonunion is not caused by other factors, such as an infection or implant failure. Early identification of patients at risk of nonunion would allow earlier intervention and may reduce treatment costs and shorten healing times.
