Pathological anatomy and dynamic effect of the displaced plantar plate and the importance of the integrity of the plantar plate-deep transverse metatarsal ligament tie-bar.

Royal Victoria Infirmary, Newcastle upon Tyne.
Annals of The Royal College of Surgeons of England (Impact Factor: 1.22). 02/1997; 79(1):58-68.
Source: PubMed

ABSTRACT Normal and deformed forefeet have been investigated by cadaver anatomical dissections and experiments, by radiographs, CT and MRI scanning, and by clinical studies. Evidence is presented to show that the skeleton of the foot rests on and is controlled by a multi-segmental ligamentous and fascial tie-bar system. Transversely across the plantar aspect of the forefoot, the plantar plates and the deep transverse metatarsal ligaments form a strong ligamentous structure which prevents undue splaying of the forefoot. Longitudinally, the five digital processes of the deeper layer of the plantar fascia are inserted into the plantar plates and control the longitudinal arch of the foot. It is suggested that many forefoot deformities result from the failure of parts of the tie-bar system and the dynamic effect of displacement of the plantar plates. Understanding this allows a more logical approach to their treatment.

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    ABSTRACT: The static support that guides motion around the lesser metatarsophalangeal joints (MTPJs) is complex. Biomechanical studies revealed important roles of both the plantar plane and collateral ligaments. Since part of the plantar plate is attached to the deep transverse metatarsal ligament (DTML), we hypothesized that the transection of the DTML in the intermetatarsal space may substantially reduce the MTPJ stability. The second, third, and fourth MTPJ stabilities of 6 fresh-frozen human cadaveric foot specimens were measured under load control. Both dorsiflexion and dorsal subluxation conditions were tested. After the intact condition was assessed, the DTML was sequentially transected such that each MTPJ had a unilateral and then a bilateral DTML transection. Stiffness data were calculated using the loading range in each test condition. Paired Student t tests were performed to test for statistical significance (P value less than .05). In intact specimens, the mean stiffness with dorsiflexion of the second, third, and fourth toes was 0.52 ± 0.15 N/deg. When the DTML was operatively transected on one side, the dorsiflexion stiffness significantly decreased 17.3% to an average of 0.43 ± 1.00 N/deg (P < .001). Subsequent transection of the DTML on the other side of each joint resulted in a further significant decrease of 5.8% to an average of 0.40 ± 0.08 N/deg (P < .001). The mean stiffness with dorsal subluxation of the intact second, third, and fourth toes was 3.55 ± 0.66 N/mm. When the DTML was operatively transected on one side, the dorsal subluxation stiffness significantly decreased 16.1% to an average of 2.98 ± 0.64 N/mm (P < .001). Subsequent transection of the DTML on the other side of each joint resulted in a further significance decrease of 7.6% to an average of 2.71 ± 0.48 N/mm (P = .016). The DTML has a significant role in maintaining lesser MTPJ ligament stability. Both unilateral and bilateral DTML transections caused substantial instability of the lesser MTPJ. The DTML is part of the natural static restraint to dorsiflexion or dorsal subluxation of the lesser MTPJ. Operative transection, injury, or degeneration of this ligament may predispose the adjacent MTPJ to instability. © The Author(s) 2014.
    Foot & Ankle International 12/2014; DOI:10.1177/1071100714563310 · 1.63 Impact Factor
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    ABSTRACT: Hallux valgus has been reported as one of the most common foot problems and is associated with age, gender and footwear. The disease imposes heavy economic and social burden on hospital expenditure, pain-suffering and manpower lost. Additionally, Hallux valgus also imposes risk of falling on elderly patients and additional risk to patients with diabetic or neuropathic feet. Different surgical and conservative treatments have been suggested. These protocols have been modified or optimized. Some physicians and researchers suggested decision-making pathway to determine the treatment to be conveyed. However, these protocols were qualitative and empirical. Although identifying the pathogenesis of hallux valgus has long been conducted, the mechanism and initialization of the pathology have not come into clear conclusion and consensus. Pathoanatomy, pathomechanics and hypermobility studies were conducted to evaluate the features of hallux valgus. Some biomechanical studies also aimed to quantify the characteristics of hallux valgus. Hallux valgus is not well-understood and remains on the research bench. There were cases of failures, complications and recurrence of interventions. Physicians are heading for better protocols and methods to improve the interventions. The objective of this study was to construct a biomechanical platform to examine the pathomechanism of hallux valgus and evaluate its interventions. The research findings enhanced understandings of hallux valgus and thus would improve treatment outcome in the long run. This biomechanical study included 3 components involving computational simulation (finite element analysis), physical experiment (to provide input to simulation and validation), and clinical study. Finite element foot model was constructed. This simulation platform was validated with physical experiments, including motion analysis, pedobarographic and cadaveric study. The data collected by the motion analysis system were also input into the simulation platform for finite element analysis. The simulation of hallux valgus initialization was mimicked by ligament laxity. The influence of ligament laxity on joint loading was investigated. The hypermobile foot (represented by the influence of ligament laxity) showed increase of metatarsocuneiform and metatarsophalangeal joint forces in all directions comparing with the normal foot. During the push-off phase, the joint forces of the metatarsocuneiform joint and the metatarsophalangeal joint were 27% and 10% larger than that of the normal foot. The increase could be due to the impairment of shock absorption. It could be also due to the extended obligation of the first ray to maintain stability upon ligament laxity. The abrupt change of the metatarsocuneiform joint force in mediolateral direction provided additional evidence on the relationship between hypermobile foot and metatarsus primus varus. The higher joint loading also suggested that foot with hypermobility could predispose risk of arthritis and joint incongruence. The simulation was continued on the evaluation of metatarsocuneiform arthrodesis, one of the hallux valgus interventions, which was reported with high failure rate (Coughlin & Mann, 2012). The objective of this simulation was to study the stress distribution of the bone graft used in the arthrodesis procedure, and thus evaluate rather inter-fragmentary compression could be achieved. The result of the simulation showed that compressive stress was ensured at the superior portion of the bone graft and tensile stress happened on the inferior side during stance. The magnitude of the stress increased drastically with about 20% of the graft volume exceeded 4MPa upon the initial push-off. The graft used for arthrodesis might absorb the physiological motion by sustaining bending stress that attributed to difficulty in fusion. The traditional metatarsocuneiform arthrodesis might not guarantee inter-fragmentary compression. Parametric study on the resection angle and the graft stiffness can be conducted to study possible improvement on the procedure. A modified soft tissue procedure for hallux valgus (syndesmosis procedure) was evaluated. A retrospective study on the patients pre-operatively and 2-year follow-up was conducted. The evaluation included questionnaires, radiographic and plantar pressure evaluation. The objective of this study was to evaluate the clinical satisfactoriness as well as the biomechanical outcome of this surgical procedure. The retrospective study demonstrated good clinical, radiological outcome, and improved load-bearing under the hallux and the first ray in the plantar pressure study. This study presented a comprehensive biomechanical platform starting with the research on the biomechanics of hallux valgus using a validated computational model. The computational model was then used to study the interventions of hallux valgus. Evaluation of intervention was also carried out in the clinical sector, based on clinical, radiological and biomechanical measurements.
    10/2013, Degree: PhD, Supervisor: Aaron Kam-Lun Leung
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    ABSTRACT: Osteotomy procedures have been the most popular approach to hallux valgus deformity correction. Soft tissue approaches have, in general, been regarded as ineffective for moderate and severe hallux valgus deformities. Osteodesis is a soft tissue technique that has been shown to be effective in the past but is still seldom practiced. In the present report, we describe a retrospective study of 63 hallux valgus feet in 36 patients who had undergone the osteodesis procedure. Their mean age was 46 ± 12 years, and the mean follow-up period was 25.4 ± 9.6 months. The surgical technique consisted of metatarsus primus varus deformity correction by intermetatarsal cerclage sutures and hallux valgus deformity correction by rebalancing the ligaments. The first metatarsophalangeal angle improved from a mean of 32.5° ± 7.6° preoperatively to 18.4° ± 7° postoperatively, the first intermetatarsal angle improved from 14.6° ± 2.6° to 6.8° ± 1.8°, and the American Orthopaedic Foot and Ankle Society score improved from 59 ± 14 to 93 ± 8 points. The rate of patient satisfaction after surgery was 92% (33 of 36 patients, 59 of 63 feet). The complications included a second metatarsal stress fracture in 3 feet (5%), metatarsophalangeal joint medial subluxation in 3 feet (5%), and metatarsophalangeal joint stiffness in 5 feet (8%). This soft tissue, nonosteotomy procedure was a safe technique that effectively corrected hallux valgus and metatarsus primus varus deformities of various severities without osteotomy or fusion. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.
    The Journal of foot and ankle surgery: official publication of the American College of Foot and Ankle Surgeons 11/2014; DOI:10.1053/j.jfas.2014.09.011 · 0.98 Impact Factor


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