Biomechanical analysis of two fixation methods for proximal chevron osteotomy of the first metatarsal

Abstract

Purpose The proximal chevron osteotomy provides high correctional power. However, relatively high rates of dorsiflexion malunion of up to 17 % are reported for this procedure. This leads to insufficient weight bearing of the first ray and therefore to metatarsalgia. Recent biomechanical and clinical studies pointed out the importance of rigid fixation of proximal metatarsal osteotomies. Therefore, the aim of the present study was to compare biomechanical properties of fixation of proximal chevron osteotomies with variable locking plate and cancellous screw respectively. Methods Ten matched pairs of human fresh frozen cadaveric first metatarsals underwent proximal chevron osteotomy with either variable locking plate or cancellous screw fixation after obtaining bone mineral density. Biomechanical testing included repetitive plantar to dorsal loading from 0 to 31 N with the Results The variable locking plate construct reveals statistically superior results in terms of bending stiffness and dorsal angulation compared to the cancellous screw construct. There was a statistically significant correlation between bone mineral density and maximum tolerated load until construct failure occurred for the screw construct (r=0.640, p=0.406). Conclusion The results of the present study indicate that variable locking plate fixation shows superior biomechanical results to cancellous screw fixation for proximal chevron osteotomy. Additionally, screw construct failure was related to levels of low bone mineral density. Based on the results of the present study we recommend variable locking plate fixation for proximal chevron osteotomy, especially in osteoporotic bone.

Evaluation of Two Types of Intramedullary Jones Fracture Fixation in a Cyclic and Ultimate Load Model

“…The load to failure test aims to simulate maximum applied forces at the time of full return to competitive sports. Similar test setups to approximate weight‐bearing have been carried out in hallux surgery and Jones fracture studies …”

“…A longitudinal line was drawn on the metatarsal to check for the rotational alignment during Jones fracture creation and fixation. According to Lawrence and Botte's classification of proximal fifth metatarsal fractures, the Jones fracture (Zone II) is a transverse fracture at the meta‐diaphyseal junction without extension distal to the 4‐5 intermetatarsal joint . A complete transverse fracture was subsequently created with an oscillating saw at the distal aspect of the 4‐5 intermetatarsal articular facet.…”

“…The number of load cycles was chosen based on the loading rate for a physiologically normal lower limb, which is approximately 5000 cycles per day. One thousand cycles per day was assumed to realistically simulate post‐operative loading in an active patient . The load–displacement curves for each construct were filtered using the digital Savitzky–Golay filter before analysis .…”

“…According to Lawrence and Botte's classification of proximal fifth metatarsal fractures, the Jones fracture (Zone II) is a transverse fracture at the meta-diaphyseal junction without extension distal to the 4-5 intermetatarsal joint. 13,26,34,35 A complete transverse fracture was subsequently created with an oscillating saw at the distal aspect of the 4-5 intermetatarsal articular facet. The proximal part of the bone was held in place with a small forceps and the appropriate JFXS or HCS was implanted with respect to the "fit and fill" principle.…”

Comparison of Plantar Pressure Distribution and Functional Outcome after Scarf and Austin Osteotomy

“…A myriad of potential operative techniques have been described for the treatment symptomatic hallux deformities. Most of the procedures are based on first metatarsal correction osteotomies. Whether or not to perform a distal or proximal osteotomy remains an important operative decision, especially in active patients without existing clinical or radiographic arthritis.…”