Biomechanical Study on the Stress Distribution of the Knee Joint After Tibial Fracture Malunion with Residual Varus–Valgus Deformity

Abstract

ObjectiveTo investigate the effect of residual varus and valgus deformity on the stress distribution of the knee joint after tibial fracture malunion.MethodsFourteen adult cadaver specimens were selected to establish the models of tibial fractures, which were fixed subsequently at neutral position (anatomical reduction) and malunion positions (at 5°, 10°, and 15° valgus positions, and 5°, 10°, and 15° varus positions). The stress distribution on the medial and lateral plateau of the tibia was quantitatively measured using ultra‐low‐pressure sensitive film technology. The changes in the stress distribution of the knee joint after tibial fracture malunion and the relationship between the stress values and the residual varus or valgus deformity were analyzed.ResultsUnder 400 N vertical load, the stress values on the medial and lateral plateau of the tibia at the neutral position were 1.137 ± 0.139 MPa and 1.041 ± 0.117 MPa, respectively. When compared with the stress values measured at the neutral position, the stress on the medial plateau of the tibia was significantly higher at varus deformities and lower at valgus deformities, and the stress on the lateral plateau was significantly higher at valgus deformities and lower at varus deformities (all P < 0.05). The stress values on the medial plateau of the tibia were significantly higher than the corresponding data on the lateral plateau at neutral and 5°, 10°, and 15° varus deformities, respectively (all P < 0.05), and significantly lower than the corresponding data on the lateral plateau at 5°, 10°, and 15° valgus deformities, respectively (all P < 0.05).ConclusionResidual varus and valgus deformity after tibial fracture malunion can lead to obvious changes of the stress distribution of the knee joint. Therefore, tibial fractures should be reduced anatomically and fixed rigidly to avoid residual varus–valgus deformity and malalignment of lower limbs.

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“…14 There is evidence to support contributions from the mechanical hypothesis from biomechanical, animal, and human studies. Biomechanical investigations have demonstrated varus/valgus deformity asymmetrically increases monolateral compartment joint pressure by 50%, 17 and rabbit studies have confirmed overloading and cartilage damage in the theoretically overloaded compartments. 18 Clinical studies of malunion have been less consistent, perhaps related to study design and flaws in the analysis of the associated deformities.…”

Tibial Malunion With Angular Deformity Managed With Corrective Osteotomy and Philos Plating in a 15-Year Male - Case Report and Review of Literature

“…Studies show that an individual with tibial fractures that heal with residual deformity may have increased risk of pain and stiffness in knee and ankle joints. Residual varus and valgus deformity after tibial fracture malunion can lead to obvious changes of the stress distribution of the knee joint 8,9 . Therefore, tibial fractures should be reduced anatomically and fixed rigidly to avoid residual varus-valgus deformity and malalignment of lower limbs 10 .…”

Biomechanical Study on the Stress Distribution of the Knee Joint After Distal Femoral Fracture Malunion With Residual Varus-valgus Deformity

“…As the pressure-sensitive lm material change with the humidity and temperature, the color development is also different. Therefore, humidi ers and air conditioners are used in this experiment to keep the indoor temperature at 25 ~ 30℃ and the relative humidity at 35% RH ~ 80% RH [22]. FPD-305E densitometer and FPD-306E pressure transducer (Fuji Company, Japan) were used to read the stress values of the ultra-low pressure sensitive lms.…”