Long Plantar Research Articles

Contribution of the plantar fascia and long plantar ligaments to the stability of the longitudinal arch of the foot

The contribution of the Plantar Fascia (PF) and Long Plantar Ligament (LPL), two ligaments extending from the hindfoot to the forefoot, to arch stability has been studied in the past using in vivo, in vitro, and in silico methodologies. In silico studies were based on one single model obtained from one single subject and did not account for the known inter-subject morphological and biomechanical variations. In the present study, we developed computational dynamic models of nine different legs obtained from nine different individuals to evaluate the role of the LPL and PF in arch support, accounting for biological differences between subjects. These models were validated by comparing the simulation results against experimental results from the corresponding cadaver legs. After validation, we simulated body weight conditions for each model by applying a vertical load to the tibia, starting from zero and increasing linearly to 720 N. Kinematic and dynamic parameters, including the variation of the medial arch angle and of the navicular height, as well as the passive forces developed by the LPL and PF, were used to evaluate the contribution of these ligaments to arch support under body weight. The results indicate that a total collapse of the medial longitudinal arch occurred only when both the LPL and PF were absent, but a stable arch was maintained when either one of these two ligament structures were present. The results varied significantly among the specific models, highlighting the importance of using multiple models to account for inter-subject morphological differences.

Morphological characteristics of the plantar calcaneocuboid ligaments

BackgroundThe aim of this study was to clarify the differences in morphological features between the long plantar ligament (LPL) and the short plantar ligament (SPL).MethodsThis investigation examined 50 legs from 25 Japanese cadavers. The LPL and SPL of each leg were classified into one of three types based on the shape and number of fiber bundles. Then, fiber bundle length, fiber bundle width, and fiber bundle thickness were measured.ResultsThe LPL was rectangular in shape (Type I) in 12%, hourglass shape (Type II) in 62%, and triangular in shape (Type III) in 26%. The SPL was a single fiber bundle (Type I-a) in 26%, a surface fiber bundle and a deep fiber bundle (Type I-b) in 60%, and a surface fiber bundle (medial and lateral) and a deep fiber bundle (Type II) in 14%. Regarding the morphological characteristics, there were no significant differences among the types in the LPL, but there were differences between types and between surface and deep fiber bundles in the SPL.ConclusionsFor the LPL, the hourglass shape is the most common type. However, there appeared to be no functional difference due to the difference in the shape of the LPL, since there were no significant differences among the types in the LPL. For the SPL, there were types of single, double and triple fiber bundles; there may be functional differences based on the number of fiber bundles and between superficial and deep fibers.

Morphological features of the lateral plantar ligament of the transverse metatarsal arch.

The aim of this study was to elucidate the morphological characteristics of the lateral Lisfranc ligament in a large sample. This investigation examined 100 legs from 50 cadavers. Each of the lower limbs was dissected to identify the plantar aspect of the transverse metatarsal arch, and morphological characteristics of the lateral plantar ligament were assessed, including the length, width, and thickness of the fiber bundles. The majority of plantar ligaments originated from the base of M5 and the plantar aspect of the lateral cuneiform (LC). The lateral plantar ligament could be classified into three types: Type I, a band-like fiber bundle originating from the base of M5 to the LC (41%); Type II, originating from the base of M5 and the plantar aspect of LC and mostly connected the blending the fiber bundles of the tibialis posterior (TP) and long plantar ligament (LPL) (21%); and Type III, with no ligaments originating from the base of M5 and plantar aspect of the LC (38%). The morphological characteristics of Type I lateral plantar ligament were as follows: length, 31.8 ± 3.7 mm; width, 2.3 ± 1.0 mm; and thickness, 0.2 ± 0.3 mm. The morphology of the lateral plantar ligament showed variation, originating from the base of M5 and the plantar aspect of LC most commonly, but this was not the case in 38% of limbs. The findings suggest that the lateral plantar ligament might play a role in the transverse tarsal arch, indicating a cooperative mechanism with the TP and LPL.

Anatomical Study of the Cuboid and Its Ligamentous Attachments and Its Implications for a Cuboid Osteotomy.

Background:Lateral column lengthening (LCL) for flexible flatfoot is an effective surgery with powerful correction of deformity because it tightens only the lateral third of the long plantar ligament (LPL). However, LCL has been associated with joint damage at the osteotomy site and loss of foot flexibility owing to joint fixation. We focused on the cuboid and investigate a novel anatomical LCL osteotomy site that effectively tightens the LPL without damaging any joints.Methods:We studied 24 feet of 12 cadavers (mean age, 80.8 years). The lengths of the LPL and short plantar ligament, locations of the attachments, and shape and location of the cuneocuboid joint on the medial side of the cuboid were studied. ImageJ software was used to measure the osteotomy angle.Results:The lateral cuboid attachment of the LPL on average was located 4.6 mm from the calcaneocuboid joint, and the cuneocuboid joint on average was located 6.7 mm from the cuboid-metatarsal joint on the medial surface of the cuboid. The direct line connecting the anterior cuneocuboid joint and the oblique crest of the cuboid on average was at a 10.3-degree inclination posterior to the cuboid-metatarsal joint.Conclusion:A straight line must be selected between a point 4 mm from the calcaneocuboid joint laterally and 6 mm from the cuboid-metatarsal joint medially at a 10-degree posterior tilt to the cuboid-metatarsal joint to perform a cuboid osteotomy LCL without damaging the articular surface.Clinical Relevance:We investigated a potential novel cuboid osteotomy method for LCL.

Anatomic Characteristics of Tissues Attached to the Fifth Metatarsal Bone.

Background:Two types of stress, bending stress and traction stress, have been reported to be involved in the mechanism of Jones fracture. However, little is known about the risk factors for traction stress.Purpose:To classify the attachment position of the peroneus brevis muscle (PB), peroneus tertius (PT), lateral band of the plantar aponeurosis (LB), and the long plantar ligament (LPL), focusing on the zone where a Jones fracture occurs (zone 2), and to compare the footprint area of each tissue type.Study Design:Descriptive laboratory study.Methods:This study examined 102 legs from 55 Japanese cadavers. Type classification was performed by focusing on the positional relationship between each tissue attachment and the zone where Jones fracture occurs (zone 2). The classifications were as follows: type I, attached proximal to the border between zones 1 and 2; type IIa, attached to the border between zones 1 and 2 with one attached part; and type IIb, attached across the border between zones 1 and 2 with two or more attached parts. The footprint areas of the PB, PT, LB, and LPL were compared between tissue types and within each attachment classification.Results:The PB was recorded as type I in 41 feet (40.2%), type IIa in 56 feet (54.9%), and type IIb in 5 feet (4.9%); the PT was recorded as type IIa in 54 feet (60.0%) and type IIb in 36 feet (40.0%); and the LB was recorded as type I in 27 feet (26.5%) and type IIa in 75 feet (73.5%). The LPL did not attach to the fifth metatarsal bone. No significant difference was found in the footprint area between type I PB and type I LB.Conclusion:The results indicate that type I, which attaches proximal to zone 2, occurs with PB and LB, and there was no significant difference in the footprint area between them. These findings suggest that type I is involved in traction stress. In the future, biomechanical research based on the results of this study will be necessary.Clinical Relevance:The results of this study provide basic research for investigating the mechanism of Jones fracture and the cause of delayed healing.

Ultrasonographic evaluation of cross-sectional area of tarsal ligaments in Standardbred Trotter Horses

ABSTRACTUltrasound evaluations of the cross-sectional area (CSA) in the tarsal region of Standardbred Trotter Horses (STH) have been previously reported for tendons but not for ligaments. The objective of this study was to identify normal ultrasonographic CSAs in the tarsal ligaments of STH. Transverse echographic scans of ligaments at five tarsal levels from proximal to distal direction were recorded in 25 healthy STH. All images were recorded, and the CSA measurements (mean ± SD) were determined. The widest structure resulted in the long plantar ligament (LPL) at distal portion of the astragalus, and the smallest was the long medial collateral ligament (LMCL) at the medial malleolus of the tibia. Long collateral ligaments (LCL) increased their CSA at the level of their distal insertions, while LPL reached the maximum CSA in the middle of its length. Although this report was limited due to its retrospective design, it is the opinion of the authors that the normal CSAs investigated in this paper could function as a reference guide when tarsal pathological conditions are suspected in STH.

Effect of injury to plantar ligaments on plantar pressure distribution

Objective To explore the changes in plantar pressure distribution and contact area after injury to the plantar ligaments in a normal adult cadaveric model. Methods Seven fresh adult cadaverie feet were used in the test. F-scan insoles were put under the plantar aspect of the feet when the specimens were loaded to 700 N vertieally. The plantar pressure data in the specimens were collected and stored before and after the plantar fascia, spring ligament, short plantar ligament and long plantar ligament were sectioned. Results were statistically analyzed. Results The peak pressure was always observed at the hindfoot area in all conditions. The peak plantar pressure on the forefoot was observed at the third metatarsal area and in-creased when the plantar ligaments were sectioned, while the total contact area of the foot was constant in both intact and pathological situations. Conclusion After the plantar ligaments are injured, the plantar pressure of the foot changes significantly and the pressure concentration occurs at the lateral foot, which may lead to clinical symptoms. Key words: Foot injury; Ligaments; Plantar pressure; Biomechanies