Foot & Ankle International - July 2018 - 840

840

Foot & Ankle International 39(7)

Table 2. Biomechanical Values of Suture Configurations in Plantar Plate Repair.
Peak Load to Failure, N
Horizontal mattress
Luggage tag
Mason-Allen

Displacement at Failure, mm

Cycles Until 2 mm of Displacement

Stiffness, N/mm

9.3 ± 2.0
8.1 ± 1.6
7.6 ± 1.6

19.2 ± 1.5
18.6 ± 2.9
18.8 ± 2.0

52.6 ± 2.8
50.3 ± 10.5
53.9 ± 4.9

115.5 ± 16.0
102.4 ± 19.3
90.0 ± 15.8a

Significant difference following analysis of variance post hoc analysis.

Figure 4. Peak load-to-failure for each suture construct.
*Statistically significant difference.

significant difference between the mattress and the luggagetag configurations or the luggage-tag and the Mason-Allen
configurations. There were no significant differences in displacement at the time of failure (mattress: 9.3 + 2.0; luggage tag: 8.1 + 1.6; Mason-Allen: 7.6 + 1.6; P = .108).
The stiffness of each suture construct was determined
on each specimen. There were no significant differences
between constructs (mattress: 52.6 ± 2.8 N/mm; luggage
tag: 50.3 ± 10.5 N/mm; Mason-Allen: 53.9 ± 4.9 N/mm;
P = .546).

Discussion
The goal of this study was to compare the biomechanical
properties of three suture configurations that may be used in
anatomic plantar plate repairs for treatment of lesser toe
instability. In this cadaveric model, the horizontal mattress
configuration demonstrated better peak load-to-failure
force compared with the Mason-Allen configuration.
Although the horizontal mattress was not statistically different from the luggage-tag configuration, the horizontal
mattress trended toward a higher load-to-failure force. In
addition, the luggage-tag configuration was not significantly different from the Mason-Allen configuration. All
specimens failed via suture cutout of the plantar plate as
opposed to suture rupture or failure at the knot. There were
no differences in displacement between constructs at the
time of failure or number of cycles required to produce 2
mm of displacement.
Anatomic repair of the plantar plate has become a viable
treatment option for dorsal MTP joint instability24,27,38,40;

however, this procedure is still associated with residual
deformity and patient dissatisfaction.12,16,26,36 Although different suture configurations for plantar plate repair have
been described, there have not been any biomechanical
studies comparing the strengths of suture configurations
with regard to their ability to grasp the plantar plate.
Analogous to rotator cuff repairs of the shoulder in which
the tendon-bone interface must be maintained to allow for
biological healing, the goal of plantar plate repair is to provide strong fixation of ligament to bone to minimize gap
formation and maintain the ligament-bone interface until
biological healing is accomplished.5 In the case of rotator
cuff repairs, the suture-tendon interface has been identified
as the weakest point in repairs,9 and gap formation of 5 mm
or more between the tendon edge and bone after repair has
been postulated to prevent healing of tendon to bone.3
Similarly, gap formation between the distal edge of the
plantar plate and the proximal phalanx may prevent biological healing after repair.
Histological studies of the plantar plate have found that
the collagen fibers are oriented longitudinally, with some
oblique bundles scattered throughout the matrix.17 Up to
30% of repaired plantar plates have residual dorsal displacement of the toe at the MTP joint.27 Part of this seemingly high failure rate may be that currently used suture
configurations do not adequately grasp the longitudinally
oriented collagen bundles of the plantar plate, causing cutout and gapping at the suture-ligament interface. We chose
to include in this comparison the modified Mason-Allen
stitch, which has been identified as one of the strongest configurations in rotator cuff repairs.22 Locking stitches of this
nature have not been described in plantar plate repairs, and
it was thought that this configuration may resist pulling
through the longitudinally oriented collagen bundles of the
plantar plate. However, in the current model, the horizontal
mattress configuration proved superior with respect to peak
load-to-failure force. The plantar plate and rotator cuff are
different tissues both in terms of size and function, which
makes a direct comparison more difficult. One possible
explanation for the horizontal mattress demonstrating a
higher load-to-failure than the Mason-Allen in the plantar
plate is the force distribution of each configuration on the
plantar plate. The horizontal mattress may better distribute
force across the entirety of the distal plantar plate as each
tail of the suture exits medially and laterally. Alternatively,

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