Histologic anatomy of the lesser metatarsophalangeal joint plantar plate

Traumatic irreducible dislocation of the fifth metatarsophalangeal joint in pediatrics: case report and clinical experience

Dislocation of the metatarsophalangeal joint (MTPJ) by trauma commonly occurs in adults. Most dislocations of the MTPJ could be reduced by closed reduction. However, isolated traumatic irreducible dislocation of the fifth MTPJ is an extremely rare injury, particularly in children. We report the case of a 10-year-old boy with irreducible dislocation of the fifth MTPJ who presented with a dorsiflexion injury of the right foot 1 year previously. Closed reduction was attempted but failed. Computed tomography showed the dorsolateral dislocation of the fifth MTPJ. We performed an open reduction and metatarsal bone osteotomy, with a short osteotomy at approximately 0.8 cm. The osteotomy was adjusted to a reduction of the MTPJ and fixation by a lock compression plate. The distal growth plate in the metatarsal bone was protected to avoid pre-closure of the growth plate. There were no instances of dislocation or signs of avascular necrosis of the head of the metatarsal bone. The results of this study demonstrated that open reduction and metatarsal bone osteotomy could be an optional treatment for irreducible dislocation of the fifth MTPJ in children. We should pay more attention to the distal growth plate in the metatarsal bone to avoid pre-closure of the growth plate.

Anatomy: Plantar Plate

The fibrocartilaginous component of the plantar plate offers stability at the metatarsophalangeal joint. In conjunction with the attachments of the deep transverse metatarsal ligaments and collateral ligaments, the plantar plate complex resists tensile forces anchored by the plantar fascia and compression forces under the metatarsal heads.

Plantar Plate Repair for Metatarsophalangeal Joint Instability of the Lesser Toes

The plantar plate is a known stabilizer of the lesser toe metatarsophalangeal (MTP) joint. MTP instability is a known common cause of metatarsalgia, most commonly in the second toe. In the last decade, clinical staging and anatomic grading mechanisms have been published to guide the surgeons on the treatment of MTP instability; this has also led to an understanding of how plantar plate tears relate to MTP joint instability. Direct surgical repair of the plantar plate has been described, short-term outcomes have been published, and the results are not perfect, but promising with respect to patient satisfaction and pain relief.

High-resolution 3T magnetic resonance imaging and histological analysis of capsuloligamentous complex of the first metatarsophalangeal joint

Background

There are discrepancies in the understanding of the structure of the capsuloligamentous complex of the first metatarsophalangeal joint (MTPJ); this study aims to investigate the differences with previous anatomical reports of high-resolution 3T magnetic resonance imaging (MRI) and histological analysis in illustrating the structure of the capsuloligamentous complex of the first MTPJ.

Methods

Nine fresh frozen cadaveric feet specimens (from two women and three men; aged 32 to 58 years) were used in this study. All specimens underwent MR examination with T1-weighted imaging and T2-weighted spectral attenuated inversion recovery in three planes. Subsequently, all cadaveric feet specimens were sliced into 2-mm-thick sections. The MRI features of the capsuloligamentous complex of the first MTPJ were analyzed in these specimens. Hematoxylin–eosin and Masson’s trichrome staining methods were used to explore the histologic features of the capsuloligamentous complex of the first MTPJ.

Results

Different from most previous studies, our results showed that the plantar plate could be divided into four portions including the central portion of the plantar plate, the intersesamoid, the sesamoid phalangeal and the metatarsosesamoid ligaments. The normal central portion of the plantar plate could be clearly visualized in the sagittal and coronal plane MR images. The intersesamoid ligament is a continuation of the central portion of the plantar plate on the sagittal plane on the gross specimen, the MR imaging, and the histological examination. On the coronal plane of the gross specimen and MR imaging, the sesamoid phalangeal ligaments and the central portion of the plantar plate can be seen as separate ligaments, but they appeared interwoven with the same continuous collagenous fibers on the histological analysis.

Conclusion

High-resolution 3T MRI allows accurate demonstration of the different anatomical details of the capsuloligamentous complex of the first MTPJ from previous anatomical reports. The histological analysis provides further understanding of the structures of the capsuloligamentous complex of the first MTPJ from previous studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02795-7.

Ultrasound findings of plantar plate tears of the lesser metatarsophalangeal joints

Lesser metatarsophalangeal (MTP) joint plantar plate tears are a common and increasingly recognised cause of metatarsalgia, MTP joint instability and forefoot deformity. Increased interest in early accurate diagnosis of plantar plate tears follows recent surgical innovations allowing direct plantar plate repair. The purpose of this review is to describe the ultrasound features of normal lesser MTP joint plantar plates and to characterise and illustrate the direct and indirect ultrasound findings of plantar plate tears. Lesser MTP joint plantar plate tears are most commonly located at the 2nd MTP joint, involving the lateral distal plantar plate insertion with variable propagation medially and proximally. The most common ultrasound appearance of a plantar plate tear is a discrete partial or full thickness hypoechoic defect in the plate substance. Flattening and attenuation or non-visualisation of the plantar plate represent more extensive tears. Dynamic imaging with toe dorsiflexion improves visualisation of tears and augments MTP joint subluxation. A common indirect finding is pericapsular fibrosis along the MTP joint capsule adjacent to a plantar plate tear, which requires differentiation from Morton's neuroma, and key distinguishing features at ultrasound are described. Other indirect findings include the cartilage interface sign, flexor tendon subluxation onto the metatarsal head or medial to the midline, flexor tenosynovitis, proximal phalangeal enthesophytes or avulsion and MTP joint synovitis. Ultrasound offers several advantages over MR imaging but requires a meticulous ultrasound examination, and optimisation of scanning technique is described.

Presence of Neovascularization in Torn Plantar Plates of the Lesser Metatarsophalangeal Joints

BACKGROUND

Recent surgical techniques have focused on anatomic repair of lesser toe metatarsophalangeal (MTP) plantar plate tears, yet it remains unknown whether the plantar plate has the biological capacity to heal these repairs. Therefore, a better understanding of the plantar plate vasculature in response to injury may provide further insight into the potential for healing after anatomic plantar plate repair. Recently, a study demonstrated that the microvasculature of the normal plantar plate is densest at the proximal and distal attachments. The purpose of this study was to compare the intact plantar plate microvasculature network to the microvasculature network of plantar plates in the presence of toe deformity using similar perfusion and nano-computed tomographic (CT) imaging methods.

METHODS

Seven fresh-frozen human cadaveric lower extremities with lesser toe deformities including hammertoe or crossover toe were perfused using a barium solution. The soft tissues of each foot were counterstained with phosphomolybdic acid (PMA). Then using nano-CT imaging, the second through fourth toe metatarsophalangeal joints of 7 feet were imaged. These images were then reconstructed, plantar plate tears were identified, and 11 toes remained. The plantar plate microvasculature for these 11 toes was analyzed, and calculation of vascular density along the plantar plate was performed. Using analysis of variance (ANOVA), this experimental group was compared to a control group of 35 toes from cadaveric feet without deformity and the vascular density compared between quartiles of plantar plate length proximal to distal. A power analysis was performed, determining that 11 experimental toes and 35 control toes would be adequate to provide 80% power with an alpha of 0.05.

RESULTS

Significantly greater vascular density (vascular volume/tissue volume) was found along the entire length of the plantar plate for the torn plantar plates compared to intact plantar plates (ANOVA, P < .001). For the first quartile of length (proximal to distal), the vascular density for the torn plantar plates was 0.365 (SD 0.058) compared to 0.281 (SD 0.036) for intact plantar plates; in the second quartile it was 0.300 (SD 0.044) vs 0.175 (SD 0.025); third quartile it was 0.326 (SD 0.051) vs 0.117 (SD 0.015); and fourth (most distal) quartile was 0.600 (SD 0.183) vs 0.319 (SD 0.082).

CONCLUSION

Torn plantar plates showed increased vascular density throughout the length of the plantar plate with an increase in density most notable in the region at or just proximal to the attachment to the proximal phalanx. Our analysis revealed that torn plantar plates exhibit neovascularization around the site of a plantar plate tear that does not exist in normal plantar plates.

CLINICAL RELEVANCE

The clinical significance of the increased vascularity of torn plantar plates is unknown at this time. However, the increase in vasculature may suggest that the plantar plate is a structure that is attempting to heal.

Outcomes Study of an Innovative Method of Direct Repair of Metatarsophalangeal Joint Instability With an Angiocatheter Needle

Plantar plate tears are a common cause of forefoot pain and digital deformity. Repair of the plantar plate has been described from both a dorsal and plantar approach, each with its own benefits and drawbacks. Many of the approaches use costly devices. Our innovative repair method uses low-cost materials available in most operating room settings. We undertook a retrospective case series study to evaluate outcomes in patients who had undergone plantar plate repair with our method of repair. A review was performed to identify patients with plantar plate disruptions treated with this approach by a single surgeon. Clinical position and patient satisfaction of the involved joints were evaluated. Six patients (9 joints) underwent plantar plate repair using this innovative method and were evaluated at a median follow-up time of 19 (range 19 to 39) months. The mean visual analog scale pain score at final follow up was 0.8 ± 2.0. The median sagittal plane position of the toe was 2 mm (range 0 to 6) from the plantar skin of the digit to the ground. Five of the 6 patients (83%) stated that they would have the procedure again. We were able to obtain satisfactory outcomes with good alignment by repairing the plantar plate with this innovative method. Our data suggest that the described method of plantar plate repair can be used as an effective way to treat metatarsal phalangeal joint instability.

Lesser Metatarsophalangeal Instability: Diagnosis and Conservative Management of a Common Cause of Metatarsalgia

CONTEXT

Lesser metatarsophalangeal (MTP) instability is a common condition that can become debilitating and require surgery.

EVIDENCE ACQUISITION

An extensive literature review was performed through MEDLINE and Google Scholar for publications relating to the etiology, diagnosis, and treatment of lesser MTP instability using the keywords metatarsophalangeal instability, athlete, forefoot pain, and metatarsalgia from database inception to 2019.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Lesser MTP instability is a common condition, especially in the active and aging populations. It is frequently misdiagnosed, causing delays in treatment that allow for progressive pain and deformity, which prevents an active lifestyle. Fortunately, MTP instability can be diagnosed easily with the drawer test. Magnetic resonance imaging is helpful when still in doubt. Conservative treatment entails joint immobilization and gradual return to play with taping and offloading metatarsal pads.

CONCLUSION

Lesser MTP instability is a common diagnosis. Its early detection and conservative treatment can help the patient regain their previous level of activity and avoid surgery.

Microvasculature of the Plantar Plate Using Nano-Computed Tomography

BACKGROUND:

Lesser toe plantar plate attenuation or disruption is being increasingly implicated in a variety of common clinical conditions. A multitude of surgical techniques and devices have been recently developed to facilitate surgical repair of the plantar plate. However, the microvascular anatomy, and therefore the healing potential in large part, has not been defined. We investigated the microvasculature of the plantar plate by employing a novel technique involving microvascular perfusion and nano-computed tomography (nano-CT) imaging.

METHODS:

Twelve human adult cadaveric lower extremities were amputated distal to the knee. The anterior and posterior tibial arteries were perfused with a barium solution. The soft tissues of each foot were then counterstained with phosphomolybdic acid (PMA). The second through fourth toe metatarsophalangeal (MTP) joints of 12 feet were imaged with nano-CT at 14-micron resolution. Images were then reconstructed for analysis of the plantar plate microvasculature and calculation of the vascular density along the length of the plantar plate.

RESULTS:

A microvascular network extends from the surrounding soft tissues at the attachments of the plantar plate on both the metatarsal and proximal phalanx. The midsubstance of the plantar plate appears to be relatively hypovascular. Analysis of the vascular density along the length of the plantar plate demonstrated a consistent trend with increased vascular density at approximately the proximal 29% and distal 22% of the plantar plate.

CONCLUSION:

There is a vascular network extending from the surrounding soft tissues into the proximal and distal attachments of the plantar plate.

CLINICAL RELEVANCE:

The hypovascular midportion of the plantar plate may play an important role in the underlying pathoanatomy and pathophysiology of this area. These findings may have significant clinical implications for the reparative potential of this region and the surgical procedures currently described to accomplish anatomic plantar plate repair.

Use of Metatarsophalangeal Joint Dorsal Subluxation in the Diagnosis of Plantar Plate Rupture

A dorsal drawer exam, also known as a modified Lachman's test, is a common clinical test for plantar plate insufficiency. This disorder presents as a dislocated metatarsophalangeal joint. The aim of this cadaveric case study was to quantify the degree of the plantar plate pathology necessary to correlate with a positive Lachman's test. The second metatarsophalangeal joint was tested on 18 cadaveric lower extremities. Limbs with previous digital surgery or with an obvious digital deformity were excluded from this study. A plantar linear incision over the plantar aspect of the second metatarsophalangeal joint was performed, and the flexor tendons were retracted to expose the plantar plate. After evaluating the plantar plate's integrity and measuring its width, a Lachman's test was then performed under fluoroscopy. The plantar plate was subsequently severed in a serial manner in 2-mm increments. A modified Lachman's test was performed with the different levels of rupture to assess the degree of dislocation. We found that a tear as small as 2 mm, detected in 12 (66.7%) of 18 specimens, produced gross instability in the second metatarsophalangeal joint. We also showed that a simulated plantar plate tear ≥4 mm but <6 mm resulted in joint subluxation (positive modified Lachman's test) with a sensitivity of 90.3%. This study reinforces the finding that a modified Lachman's test is a clinical exam that demonstrates high sensitivity in diagnosing plantar plate insufficiency.

Anatomy and Physiology of the Lesser Metatarsophalangeal Joints

Knowledge and command of anatomy is paramount to effectively treating disorders of the lesser metatarsophalangeal (MTP) joints. The osseous structures consist of the proximal phalanx of the toe and the metatarsal head. The soft tissues on the dorsum of the MTP joint include the joint capsule and the tendons of extensor digitorum longus and extensor digitorum brevis. The proper and accessory collateral ligaments form the medial and lateral walls and contribute to stability in the coronal and sagittal planes. The plantar plate forms the plantar border of the MTP joint and stabilizes the MTP joint against hyperextension and dorsal translation.

Radiographic Shape of Foot With Second Metatarsophalangeal Joint Dislocation Associated With Hallux Valgus

BACKGROUND

Second metatarsophalangeal (MTP) joint dislocation is associated with hallux valgus, and the treatment of complete dislocation can be difficult. The purpose of this study was to radiographically clarify the characteristic foot shape in the presence of second MTP joint dislocation.

METHODS

Weight-bearing foot radiographs of the 268 patients (358 feet) with hallux valgus were examined. They were divided into 2 groups: those with second MTP joint dislocation (study group = 179 feet) and those without dislocation (control group = 179 feet). Parameters measured included the hallux valgus angle (HVA), first-second intermetatarsal angle (IMA), second MTP joint angle, hallux interphalangeal angle (IPA), second metatarsal protrusion distance (MPD), metatarsus adductus angle (MAA), and the second metatarsal declination angle (2MDA). Furthermore, the dislocation group was divided into 3 subgroups according to second toe deviation direction: group M (medial type), group N (neutral type), and group L (lateral type).

RESULTS

The IPA and the 2MDA were significantly greater in the study group than in the control group. By multiple comparison analysis, the IMA was greatest in group M and smallest in group L. The IPA was smaller and 2MDA greater in group N than in group L. The HVA and MAA in group L were greatest, and MPD in group L was smallest.

CONCLUSIONS

The patients with second MTP joint dislocation associated with hallux valgus had greater hallux interphalangeal joint varus and a second metatarsal more inclined than with hallux valgus alone. The second toe deviated in a different direction according to the foot shape.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Multiplanar Correction of the Lesser Digital Deviation and Indirect Plantar Plate Rupture Repair Using a Braided Polyethylene Nylon Suture: A Technique Guide

Forefoot and lesser digital pathology continues to be a challenging area of surgical correction for foot and ankle surgeons. Many techniques for the correction of digital deformities secondary to plantar plate rupture, regardless of planal dominance, have been described including direct repair and metatarsal shortening osteotomies for repair. The authors present a new technique for multiplanar correction of deformed lesser digits without direct repair of the plantar plate rupture utilizing a specialty suture. The technique utilizes a braided synthetic polyethylene Nylon suture, which has been traditionally used for open or arthroscopic shoulder labrum repair, for the stabilization of the lesser metatarsophalangeal joint. This novel technique guide for the correction of transverse and sagittal plane deformities of the digit at the metatarsophalangeal joint negates the need for a plantar incisional approach for plantar plate repair or metatarsal head osteotomy from a dorsal approach with augmented stabilization.

LEVELS OF EVIDENCE

Level V: Expert opinion.

Modified double plantar plate tenodesis

BACKGROUND

Metatarsophalangeal joint instability of the lesser toe can cause acquired toe deformity. Plantar plate deficiency is the major pathology. Plantar plate repair can stabilize the joint but may result in iatrogenic transverse plane toe deformity in correction of claw toe deformity. Limited toe extension can be resulted after correction of crossover toe deformity by plantar plate tenodesis and extensor digitorum brevis transfer. A modification of the technique is proposed.

MATERIALS AND METHODS

The clinical outcomes of 10 patients with the modified procedure performed were assessed.

RESULTS

The correction was full in all toes with no recurrence.

CONCLUSION

The modified technique can stabilize the metatarsophalangeal joint and correct lesser toe deformity without the need of tendon transfer, osteotomy or sophisticated instrumentation.

Plantar Plate Repair for Lesser Metatarsophalangeal Joint Instability

BACKGROUND

Lesser metatarsophalangeal (MTP) joint instability is a common cause of forefoot pain. Advances in operative technique and instrumentation have made it possible to anatomically treat plantar plate tears through a dorsal approach. Our goal was to evaluate the subjective, functional, and radiographic outcomes of plantar plate repair (PPR) from a dorsal approach.

METHODS

A prospective case series was performed evaluating the results of PPR in 97 feet with 138 plantar plate tears. Patients underwent PPR from a dorsal approach with a Weil osteotomy. We followed patients at regular intervals for 12 months and collected data preoperatively and postoperatively with respect to visual analog scale (VAS) scores, MTP range of motion (ROM), paper pull-out test, American Orthopaedic Foot & Ankle Society (AOFAS) scores, satisfaction, and radiographic measures.

RESULTS

Eighty percent of patients scored "good" to "excellent" satisfaction scores at 12 months. The mean VAS pain score preoperatively was 5.4/10, and postoperatively was 1.5/10. The mean AOFAS scores increased from 49 to 81 points following surgery. The mean MTP ROM preoperatively was 43 degrees and postoperatively 31 degrees. Forty-two percent of toes passed the paper pull out test prior to surgery and 54% at 12 months. Mean metatarsal shortening was 2.4/3.1/1.2 mm for the second, third, and fourth metatarsals, respectively. The mean MTP joint angles preoperatively were 2/4.9/-1.3 degrees and postoperatively were 7.4/9.6/0.2 degrees, respectively, for the second, third, and fourth MTP joints.

CONCLUSION

We found that the plantar plate could be repaired through a dorsal approach with reliable outcomes. PPR was a viable option to anatomically restore the ligamentous support in the unstable lesser MTP joint.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Metatarsophalangeal joint stability: a systematic review on the plantar plate of the lesser toes

Background

Instability of the metatarsophalangeal (MTP) joints of the lesser toes (digiti 2–5) is increasingly being treated by repair of the plantar plate (PP). This systematic review examines the anatomy of the plantar plate of the lesser toes, and the relation between the integrity of the plantar plates of the lesser toes and lesser MTP joint stability.

Methods

The databases of Embase.com, Medline (Ovid), Web of Science, Scopus, Cochrane, Pubmed not medline, Cinahl (ebsco), ProQuest, Lilacs, Scielo and Google Scholar were searched in June 2015 from inception. Studies were included if they were in English, contained primary data, and had a focus on plantar plate anatomy of the lesser toes or on the relationship between integrity of the plantar plate and MTP joint (in)stability. Study characteristics were extracted into two main tables and descriptive anatomical and histological data were summarized into one schematic 3D drawing of the plantar plate.

Results

Nine studies were included in this systematic review, of which five addressed plantar plate anatomy as such and four focused directly and indirectly on plantar plate integrity related to MTP joint stability.

Conclusion

This is the first systematic review regarding plantar plate anatomy related to MTP joint stability of the lesser toes. This review iterates the importance of plantar plate anatomy and integrity for MTP joint stability, and it delineates the lack of primary data regarding plantar plate anatomy of the lesser toes and MTP joint stability.

Electronic supplementary material

The online version of this article (doi:10.1186/s13047-016-0165-2) contains supplementary material, which is available to authorized users.

Evaluation of lesser metatarsophalangeal joint plantar plate tears with contrast-enhanced and fat-suppressed MRI

OBJECTIVE

To present findings of plantar plate (PP) lesions from MRI with administration of gadolinium and to differentiate PP lesions from others causes of metatarsalgia.

MATERIALS AND METHODS

Two musculoskeletal radiologists reviewed 249 contrast-enhanced forefoot MRI scans from patients with metatarsalgia between June 2012 and June 2013. Evaluations focused on hyper-vascularized/fibrous tissue and other findings associated with PP tears.

RESULTS

Fifty-nine patients had PP tears, 59 % were female. Most of these patients, 48/59 (81.4 %), had a single metatarsophalangeal (MTP) PP lesion in one foot, although 7/59 patients had one lesion in each foot, 3/59 (5.1 %) had two in one foot, and 1/59 (1.7 %) had three lesions in one foot. The second MTP joint was the most common location for PP tears (n = 56), followed by the third (n = 12) and fourth (n = 3) MTP joints. Lateral (n = 33) and full thickness (n = 28) PP lesions were the most frequent, and central (n = 3) and lateral/central (n = 7) tears were less prevalent. Fifty (70.5 %) PP lesions showed pericapsular fibrosis in pre-contrast sequences, and 21 (29.5 %) were visible only after administration of gadolinium. All PP lesions had collateral ligament involvement. Others findings included interosseous tendon lesions (n = 29), interosseous tendon rupture (n = 29), synovitis (n = 49), flexor tenosynovitis (n = 28), crossover toe (n = 2), hammertoe (n = 1), intermetatarsal space (IS) neuromas (n = 11), and third IS neuromas (n = 12).

CONCLUSION

PP tears are a common cause of metatarsalgia, accounting for more than 20 % of cases in our sample. A substantial portion of the lesions (29.5 %) became visible only after the administration of gadolinium.

Can ultrasound of plantar plate have normal appearance with a positive drawer test?

OBJECTIVES

The aims of this study were (1) to evaluate the reliability of ultrasound (US) examination in the identification and measurement of the metatarsophalangeal plantar plate (MTP-PP) in asymptomatic subjects and (2) to establish the correlation of US findings with those of physical examination and magnetic resonance imaging (MRI), once it is an important tool in the evaluation of the instability syndrome of the second and third rays.

MATERIALS AND METHODS

US examinations of the second and third MTP-PPs were performed in eight asymptomatic volunteers, totaling 32 MTP joints, by three examiners with different levels of experience in musculoskeletal US. Plantar plate dimensions, integrity and echogenicity, the presence of ruptures, and confidence level in terms of structure identification were determined using conventional US. Vascular flow was assessed using power Doppler. US data were correlated with data from physical examination and MRI.

RESULTS

MTP-PPs were ultrasonographically identified in 100% of cases, always showing homogeneous hyperechoic features and no detectable vascular flow on power Doppler, with 100% certainty in identification for all examiners. There was excellent US inter-observer agreement for longitudinal measures of second and third toe MTP-PPs and for transverse measures of the second toe MTP-PP. The MTP drawer test was positive for grade 1 MTP instability in 34.4% of joints with normal US results. Transverse MTP-PP measures were significantly higher in individuals with positive MTP drawer test. US measures and characteristics of MPT-PPs were positively correlated with those of MRI.

CONCLUSIONS

US is efficient in identifying and measuring MPT-PPs and may complement physical examination. A grade 1 positive MTP drawer test may be found in asymptomatic individuals with normal MPT-PPs, as assessed by imaging.

Dorsal Approach for Plantar Plate Repair With Weil Osteotomy: Operative Technique

In recent years, the role of the plantar plate in lesser metatarsophalangeal joint stability has increasingly been recognized. Tearing or attenuation of the plantar plate often will result in crossover or hammertoe deformity with hyperextension of the MTP joint. Some patients are able to have resolution of painful symptoms with conservative treatment but for those that fail these measures, surgical fixation of the plantar plate is indicated. While, there have been some described techniques for direct repair of the plantar plate, we present a surgical technique through a dorsal approach with a Weil osteotomy which accomplishes great clinical correction of the plantar plate tear and associated toe deformity as well as relief of patient's pain. Additionally, we believe this technique is safe, efficient and reproducible.

LEVEL OF EVIDENCE

Level V, expert opinion.

The plantar plate of the first metatarsophalangeal joint: an anatomical study

The plantar plate of the first metatarsophalangeal (MP) joint is a critical structure of the forefoot that has been identified as a major stabilizer within the capsuloligamentous complex. Many studies have clarified and documented the anatomy of the lesser toe MP plantar plates, but few have looked closely at the anatomy of the first MP joint. Ten cadaveric specimens were examined to identify and document the objective anatomic relationship of the plantar plate, tibial sesamoid, and surrounding osseus structures. The average distance of the plantar plate distal insertion from the joint line into the proximal phalanx was 0.33 mm. The plantar plate was inserted into the metatarsal head on average 17.29 mm proximal from the joint line. The proximal aspect of the sesamoid was 18.55 mm proximal to the distal attachment of the plantar plate to the phalanx. The distal aspect of the sesamoid averaged 4.69 mm away from the distal attachment into the proximal phalanx. The footprint of the distal plate insertion was on average 6.33 mm in length in the sagittal plane. The authors hope that these objective data measures can aid in the understanding and subsequent surgical repair of this important forefoot structure.

Role of plantar plate and surgical reconstruction techniques on static stability of lesser metatarsophalangeal joints: a biomechanical study

BACKGROUND

Disruption of the plantar plate of the lesser metatarsophalangeal (MTP) joints leads to significant instability. Despite the fact that plantar plate disorders are common, the best mode of treatment remains controversial with operative treatments having variable and somewhat unpredictable clinical outcomes.

METHODS

Lesser MTP joints from the second, third, and fourth toes from fresh-frozen cadaver feet were biomechanically tested: (1) intact, (2) with the plantar plate disrupted, and (3) following a Weil osteotomy, a flexor-to-extensor tendon transfer, or a Weil osteotomy with a subsequent flexor-to-extensor tendon transfer with testing in superior subluxation, dorsiflexion, and plantarflexion.

RESULTS

The plantar plate significantly contributed to stabilizing the sagittal plane of the lesser MTP joints. The flexor-to-extensor tendon transfer significantly stabilized the disrupted lesser MTP joints in both superior subluxation and in dorsiflexion. The flexor-to-extensor tendon transfer following a Weil osteotomy also significantly stabilized the disrupted lesser MTP joints in both superior subluxation and in dorsiflexion.

CONCLUSIONS

In this cadaver-based experiment, disruption of the plantar plate of the lesser MTP joints led to significant instability. After plantar plate disruption, the Weil osteotomy left the joint unstable. The flexor-to-extensor tendon transfer by itself increased the stability of the joint in dorsiflexion, but combined with a Weil osteotomy restored near intact stability against superior subluxation and dorsiflexion forces.

CLINICAL RELEVANCE

Surgeons using the Weil osteotomy for plantar plate deficient MTP joints may consider adding a flexor tendon transfer to the procedure. Techniques to repair the torn plantar plate directly are needed.

MRI evaluation of the MTP plantar plates compared with arthroscopic findings: a prospective study

BACKGROUND

Instability of the lesser metatarsophalangeal (MTP) joints has been widely reported and plantar plate insufficiency is a key part of this pathologic process. The diagnosis is made clinically but can be aided by imaging studies, particularly magnetic resonance imaging (MRI); however, the sensitivity and accuracy of this method compared to direct visualization of these lesions has not yet been established, nor has interobserver accuracy of MRI been assessed for evaluation of plantar plate pathology. In this study, our goals were to identify the accuracy of the MRI in describing plantar plate tears when compared to direct arthroscopic visualization using an anatomic grading system and to test the influence of an anatomic grading system in the accuracy of the MRI readings.

METHODS

We evaluated the clinical exam, MRI scans, and arthroscopic findings of 35 patients with lesser MTP instability.

RESULTS

Using an anatomic grading system, a distinct improvement in the radiological evaluation and interpretation occurred. Knowledge of the pattern of plantar plate tears by a radiologist enabled them to locate and describe the type of tears of the plantar plate on the MRI. The amount of training and the experience of the radiologist were also important factors in our study. The senior radiologists had much better levels of accuracy (Group A, 77.0%; Group B, 88.5%) than less experienced radiologists.

CONCLUSION

Prior knowledge of the pathophysiology and morphological types of lesions of the plantar plates was helpful for accurate identification and description of the tears by the radiologist.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Role of collateral ligaments in metatarsophalangeal stability: a cadaver study

BACKGROUND

Lesser metatarsophalangeal joint (MTPJ) instability is a common complaint. The role each of the collateral structures play in maintaining joint stability is unknown.

METHODS

Twenty-six fresh-frozen cadaver lesser MTPJ's were tested for instability with the amount of force necessary to translate the joint 3 mm dorsally. Specimens were tested with 1) intact collateral ligaments, 2) transected accessory collateral or proper collateral ligaments (ACL or PCL), 3) repaired ACL or PCL, 4) transected ACL and PCL, 5) repaired ACL and PCL, and 6) transferred interosseous (IO) tendon. Student t-tests were performed to test for statistical significance (p value less than 0.05).

RESULTS

The mean force required for 3 mm of dorsal displacement was 25 ± 13 N (range, 11 to 52 N) in the 26 specimens. Transecting either the ACL alone or the ACL and PCL led to the most instability versus transecting the PCL alone. Repairing both ligaments improved stability. The IO tendon transfer was comparable to the direct repair of the PCL but was inferior to the direct repair of the ACL.

CONCLUSION

Both ACL and PCL have a stabilizing effect on the MTPJ. However, the ACL was more important since primary transection of the ACL led to more instability and additional transection of the PCL in an ACL deficient model did not lead to significantly more instability.

CLINICAL RELEVANCE

Direct repairs of both structures improved the stability of the joint but not back to normal. IO tendon transfer is a possible adjunct to collateral ligament repairs, but in itself is not sufficient to restore stability.

Irreducible dislocation of the fourth metatarsophalangeal joint--a case report

Traumatic dislocation of the metatarsophalangeal joint of an isolated lesser toe is an uncommon injury. We report a patient who presented 1 day after a dorsiflexion injury of the right foot. Physical examination showed a shortened and angulated right fourth toe resulting in scissoring of his digits. X-rays of the right foot confirmed complete dislocation of the fourth metatarsophalangeal joint. After failing 4 attempts at closed reduction, an orthopedic consult was made, and he underwent surgery. Six months after the operation, he developed avascular necrosis of the fourth metatarsal head. Reduction of the metatarsophalangeal of an isolated lesser toe is difficult due to the anatomical constraints imposed by the surrounding soft tissue. Failure at reduction after a single attempt by an experienced emergency physician should prompt the need for an orthopedic consult in view of likely surgery required. Avascular necrosis of the metatarsal head can also occur as a late complication after such injury.

A retrospective analysis of lesser metatarsophalangeal joint fusion as a treatment option for hammertoe pathology associated with metatarsophalangeal joint instability

Complex hammer digit deformity is commonly associated with instability of the metatarsophalangeal joint. Restoring joint stability is critical for digit alignment and function and can be challenging and unpredictable. Lesser metatarsophalangeal joint fusion might be an alternative treatment to the current soft tissue balancing, repair, and extra-articular osseous procedures used to treat joint instability. The present study was a retrospective chart and radiographic review of the pooled outcomes of 31 consecutive lesser metatarsophalangeal joint fusion procedures performed by 3 independent surgeons from May 2004 to September 2009. The clinical and radiographic outcomes were analyzed with descriptive and inferential statistics. The overall interval to radiographic union was 8.69 ± 1.7 weeks (range 6 to 12 and 95% confidence interval 7.9 to 9.4). The overall period to clinical union was 10.25 ± 4.5 weeks (range 4 to 22 and 95% confidence interval 8.5 to 11.9). The mean duration of non-weight-bearing was 4.71 ± 1.74 weeks, followed by 5.09 ± 2.8 weeks of guarded weight-bearing with a brace. Complications included nonunion in 4 (12.90%), hardware breakage in 2 (6.45%), and soft tissue infection in 1 (3.23%). Patients demonstrated a statistically significant reduction in pain (p = .035) and improved digit alignment after the procedure that enabled full return to unrestricted weight-bearing activities without limitations or the need for orthoses. These findings support metatarsophalangeal joint fusion as an alternative treatment of lesser digit metatarsophalangeal joint instability associated with hammer digit deformities that obviate the need for concomitant soft tissue procedures such as plantar plate repair or tendon balancing procedures.

A dynamic model of the windlass mechanism of the foot: evidence for early stance phase preloading of the plantar aponeurosis

In the present study we have estimated the temporal elongation of the plantar aponeurosis (PA) during normal walking using a subject-specific multi-segment rigid-body model of the foot. As previous studies have suggested that muscular forces at the ankle can pre-load the PA prior to heel-strike,the main purpose of the current study was to test, through modelling, whether there is any tension present in the PA during early stance phase. Reflective markers were attached to bony landmarks to track the kinematics of the calcaneus, metatarsus and toes during barefoot walking. Ultrasonography measurements were performed on three subjects to determine both the location of the origin of the PA on the plantar aspect of the calcaneus, and the radii of the metatarsal heads. Starting with the foot in a neutral, unloaded position, inverse kinematics allowed calculation of the tension in the five slips of the PA during the whole duration of the stance phase. The results show that the PA experienced tension significantly above rest during early stance phase in all subjects (P&lt;0.01), thus providing support for the PA-preloading hypothesis. The amount of preloading and the maximum elongation of the slips of the PA decreased from medial to lateral. The mean maximum tension exerted by the PA was 1.5 BW (body weight) over the three subjects.