Metatarsophalangeal joint pathology in crossover second toe deformity: a cadaveric study

Differential Diagnosis of Metatarsalgia

Lesser (or central) metatarsalgia is defined as pain in the forefoot under or around the lesser metatarsals and their respective metatarsophalangeal joints. Two common causes of central metatarsalgia are Morton's neuroma (MN) and plantar plate (PP) injury. Because both clinical and imaging features overlap, establishing the correct differential diagnosis may be challenging. Imaging has a pivotal role in the detection and characterization of metatarsalgia. Different radiologic modalities are available to assess the common causes of forefoot pain, so the strengths and weakness of these imaging tools should be kept in mind. It is crucial to be aware of the pitfalls that can be encountered in daily clinical practice when dealing with these disorders. This review describes two main causes of lesser metatarsalgia, MN and PP injury, and their differential diagnoses.

Intrinsic muscles of the foot: Anatomy, function, rehabilitation

The intrinsic muscles of the foot are underappreciated structures in evaluating and treating lower extremity dysfunction. These muscles play a crucial role in the proper function of the foot during sport activities. The functions of these muscles are not generally well understood. Intrinsic dysfunction can lead to a variety of problems. Therefore, it is important for clinicians to have a good understanding of the anatomy and function of the intrinsic foot muscles in order to properly diagnose and treat foot injuries in patients. Published research on the rehabilitation of the intrinsic muscles provides insight into the function as well as benefits of treatment. The purpose of this review is to summarize the published research on the anatomy, function, contribution to pathology, as well as rehabilitation options for the intrinsic muscles of the foot.

Presurgical Perspective and Postsurgical Evaluation of Plantar Plate and Turf Toe

Capsuloligamentous injury of the first metatarsophalangeal (MTP) joint (eponymously called "turf toe") mostly occurs in athletes and involves acute trauma, whereas tears of the lesser MTP joint plantar plate typically are an attritional-degenerative condition. This article reviews the anatomy, pathophysiology, mechanism and patterns of injury, grading and classification of injury, imaging appearances (pre- and postoperative), and management of first MTP joint capsuloligamentous injuries and lesser MTP joint plantar plate tears. These two distinct pathologies are discussed in separate sections.

Nonoperative Treatment of Plantar Plate Tears

The plantar plate is a critical structure involved in stabilizing the metatarsophalangeal joint. Its disruption can not only be painful for the patient but also may lead to subsequent structural deformities. There are several conservative treatment modalities available to help mitigate symptoms including splinting, offloading, and intraarticular injections. That being said, once the pathology progresses to advanced stages, these treatments are not efficacious. Reported success with conservative treatment modalities is limited to case studies and series with a low level of clinical evidence. As such, this represents an area where further investigation is needed to evaluate the true efficacy of conservative treatment and to allow for development of a more standardized approach.

Normal and Diseased Imaging: Ultrasound/MRI

The lesser metatarsophalangeal joint plantar plate and calcaneonavicular (spring) ligament are highly specialized soft tissue structures within the foot, consisting partly of fibrocartilage and capable of withstanding high compressive and tensile loads. Preoperative advanced imaging, in the form of point-of-care ultrasound and MRI, has become indispensable for surgeons hoping to confirm, quantify, and better localize injuries to these structures before surgery. This article describes the technical considerations of ultrasound and MRI and provides examples of the normal and abnormal appearances of these structures. The pros and cons of each imaging modality are also discussed.

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.

A versatile method for dorsal-approach plantar plate repair using standard operative instruments

Background

The plantar plate is an important static stabilizer of the lesser metatarsophalangeal joints, and disruptions of the plantar plate can lead to significant instability and lesser toe deformities. In recent years, direct plantar plate repair has been proposed. Although direct repair via a dorsal approach is attractive, a torn plantar plate is small and difficult to access using regular instruments in a restricted operative field.

Methods

In this report, a unique method for plantar plate repairs was used to repair various configurations of plantar plate tears with standard operative instruments that are available in most operating rooms.

Results

Using this method, 10 patients underwent plantar plate repairs, and the mean follow-up period was 24 (range, 14–38) months. The mean visual analog scale score for pain preoperatively was 4.1 (range, 0–6) and decreased to 0.6 (range, 0–3) at last follow-up. Postoperatively, the mean visual analog scale score for satisfaction was 9.6 (range, 8–10) and the mean American Orthopedic Foot and Ankle Society forefoot score was 88.8 (range, 75–100).

Conclusions

Our study proposes an inexpensive and versatile method for plantar plate repair via a dorsal approach that uses standard operative instruments.

Trial registration

ClinicalTrials.gov, NCT04949685. July 2, 2021 - Retrospectively registered,

Level of clinical evidence

4

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04951-w.

Transverse laxity of the forefoot

BACKGROUND

Splay of the forefoot reflects the loss of tension in the soft tissues and indicates failure of the biomechanics of the tie-bar system. By identifying and quantifying the soft tissue structures involved in the destruction of forefoot stability we could increase the understanding of forefoot pathologies.

METHODS

We investigated the transverse forefoot laxity on healthy feet, feet with forefoot pathology and cadaveric feet undergoing sequential dissection.

RESULTS

Statistical difference in transverse laxity was seen between healthy feet (n = 160) and feet with symptomatic forefoot pathology requiring surgery (n = 29). Presence of lesser ray pathology is associated with increased transverse laxity. For the dissected cadaveric feet (n = 9) sequential sectioning the plantar plate causes a progressive evolution of transverse laxity. The repair of plantar plates greatly improves transverse stability.

CONCLUSIONS

Forefoot pathology causes increased transverse laxity. In case of a major transverse laxity of the forefoot a plantar plate lesion should be suspected.

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.

Mallet Toes, Hammertoes, Neuromas, and Metatarsophalangeal Joint Instability: 40 Years of Development in Forefoot Surgery

BACKGROUND

Today's foot and ankle surgeon has an enhanced understanding of forefoot pathology and treatment options compared to surgeons who practiced in previous decades. This paper summarizes developments in forefoot surgery in the past 40 years, specifically in treatments for mallet toe, hammertoe, neuroma, and metatarsophalangeal joint instability.

MATERIALS AND METHODS

A review of the literature was conducted using the PubMed search engine, with key terms including, "mallet toe," "hammertoe," "neuroma," "metatarsophalangeal joint instability," "plantar plate," and "forefoot surgery." Chapters in major orthopaedic textbooks covering these topics were also reviewed. We then chronicled the history of the diagnosis and treatment of these pathologies, with a focus on the past 40 years.

CONCLUSIONS

There have been major advances in understanding and treating forefoot pathologies in the past four decades; however, there remain areas for improvement both in the diagnosis and treatment of these problems.

LEVEL OF EVIDENCE

Level V, meta-synthesis.

State of the Art in Lesser Metatarsophalangeal Instability

Advancements in lesser metatarsophalangeal (MTP) instability have involved the use of minimally invasive surgery techniques, synthetic augmentation of existing transfers, and use of arthroscopy for both diagnosing and addressing MTP disorder. Advances in imaging modalities, particularly MRI, have aided in diagnosing subtle instability. Clinical outcomes seem to be similar to traditional approaches as the indications and applicability continue to evolve.

Outcome of Second-Ray Pathologies Following Weil Osteotomy in Patients Treated for Hallux Valgus

Background: We hypothesized that the cause of second-ray pathology with hallux valgus is excessive relative length of the second metatarsal and performed Weil osteotomy to shorten it, with correction of hallux valgus. The purpose of this study is to evaluate the outcome of second-ray pathology after distal chevron osteotomy (DCO) with Weil osteotomy to correct metatarsal parabola. Methods: We performed concomitant Weil osteotomy of the second metatarsal with DCO of the first metatarsal as part of hallux valgus with second-ray pathology correction surgery in 45 feet (40 patients). Second-ray pathologies were claw toe deformity, painful plantar callosity, second metatarsophalangeal joint (MTPJ) dislocation, and osteoarthritis (OA) of the second MTPJ. We measured projection of the second metatarsal (PSM), metatarsal protrusion index (MPI), and metatarsal protrusion distance (MPD). The second-ray surgery outcome was assessed by patient satisfaction. Results: Patient satisfaction was good in claw toe deformity and OA (satisfaction rate: 60% [23 patients] and 71% [7 patients], respectively) and fair in painful plantar callosity and second MTP joint dislocation (satisfaction rate: 44% [9 patients] and 33% [6 patients], respectively). Total patient satisfaction rate was higher when the PSM, MPI, and MPD ranged between 7 and 12 mm, -5 and 0 mm, and 0 and 4 mm, respectively. Conclusions: We concluded that simultaneous performance of hallux valgus correction and Weil osteotomy in patients with second-ray pathologies associated with hallux valgus was safe as well as effective. Correcting the metatarsal parabola within the appropriate range after surgery is associated with second-ray pathology outcome. Levels of Evidence: Therapeutic studies, Level VI: Case series.

Lesser Metatarsophalangeal Joint Pathology Addressed With Arthrodesis: A Case Series

Lesser metatarsophalangeal joint pathology is a common condition facing the foot and ankle surgeon, often beginning as a mild subluxation of the toe and progressing to a full dislocation of the metatarsophalangeal joint. In severe or recalcitrant deformities, traditional conservative and surgical methods can fail to resolve the issue. We report on 4 patients with 5 severely dislocated lesser metatarsophalangeal joints with varied etiologies and comorbidities who underwent arthrodesis of these joints using screw and plate fixation. All patients achieved radiographic and clinical signs of union at an average of 16.4 weeks.

Plantar Plate Injury and Angular Toe Deformity

Lesser toe plantar plate injuries at the metatarsophalangeal (MTP) joint are a common source of metatarsalgia. The second MTP joint is the most commonly affected digit. The fibrocartilaginous plantar plate is the most important static stabilizer of the MTP joint; high loading with weight bearing can lead to attritional plantar plate injuries. Chronic pain with weight bearing is the common presentation of lesser toe instability. Untreated plantar plate instability can lead to hammer toe and mallet toe deformities. Combined Weil osteotomy and plantar plate repair yields favorable pain relief and angular deformity correction for patients who fail conservative treatment.

Biomechanical Evaluation of Suture Configurations in Lesser Toe Plantar Plate Repairs

BACKGROUND

Lesser toe metatarsal-phalangeal (MTP) joint instability can be a major source of pain and dysfunction. Instability occurs when there is incompetence of the plantar plate and/or collateral ligaments. Newer operative treatments focus on performing anatomic repairs of the plantar plate. The goal of this study was to compare the biomechanical properties of 3 suture configurations that may be used for plantar plate repairs.

METHODS

Biomechanical analysis of 27 lesser toe plantar plates from fresh frozen human cadavers was completed. The plantar plate was detached from the proximal phalanx, and suture was placed in the distal plantar plate in a horizontal mattress, luggage-tag, or Mason-Allen suture configuration. Cyclic loading followed by load-to-failure testing was performed.

RESULTS

There was a significant difference in peak load-to-failure force between constructs (mattress: 115.53 ± 15.95 N; luggage-tag 102.42 ± 19.33 N; Mason-Allen: 89.96 ± 15.78 N; P = .015). Post hoc analysis demonstrated that the mattress configuration had significantly higher load-to-failure force compared with the Mason-Allen configuration ( P = .004). There were no significant differences between the mattress and the luggage-tag configurations or the luggage-tag and the Mason-Allen configurations. There were no differences in construct stiffness, axial displacement at the time of failure, or number of cycles required to produce 2 mm of displacement.

CONCLUSION

The mattress configuration demonstrated better peak load-to-failure force compared with the Mason-Allen configuration but was not statistically different from the luggage-tag configuration. Although not significant, the mattress configuration trended toward higher load-to-failure force compared with the luggage-tag.

CLINICAL RELEVANCE

The horizontal mattress stitch may be the biomechanically superior configuration in plantar plate repairs.

Association Between Second Metatarsal Length and Forefoot Loading Under the Second Metatarsophalangeal Joint

BACKGROUND

Metatarsal length is believed to play a role in plantar plate dysfunction, although the mechanism through which progressive injury occurs is still uncertain. We aimed to clarify whether length of the second metatarsal was associated with increased plantar pressure measurements in the forefoot while walking.

METHODS

Weightbearing radiographs and corresponding pedobarographic data from 100 patients in our practice walking without a limp were retrospectively reviewed. Radiographs were assessed for several anatomic relationships, including metatarsal length, by a single rater. Pearson correlation analyses and multiple linear regression models were used to determine whether metatarsal length was associated with forefoot loading parameters.

RESULTS

The relative length of the second to first metatarsal was positively associated with the ratio of peak pressure beneath the respective metatarsophalangeal joints ( r = 0.243, P = .015). The relative length of the second to third metatarsal was positively associated with the ratios of peak pressure ( r = 0.292, P = .003), pressure-time integral ( r = 0.249, P = .013), and force-time integral ( r = 0.221, P = .028) beneath the respective metatarsophalangeal joints. Although the variability in loading predicted by the various regression analyses was not large (4%-14%), the relative length of the second metatarsal (to the first and to the third) was maintained in each of the multiple regression models and remained the strongest predictor (highest standardized β-coefficient) in each of the models.

CONCLUSIONS

Patients with longer second metatarsals exhibited relatively higher loads beneath the second metatarsophalangeal joint during barefoot walking. These findings provide a mechanism through which elongated second metatarsals may contribute to plantar plate injuries.

LEVEL OF EVIDENCE

Level III, comparative study.

Lesser Metatarsophalangeal Joint Instability: Treatment with Tendon Transfers

Complex digital deformities and metatarsophalangeal joint instability encompass a wide range of pathology, and we must identify the different degrees of ligamentous disruption. It is important to address a combination of procedures to treat gross deformities of the lesser toes. Surgical treatment should be individualized and requires a sequential process for adequate reduction and deformity correction. There is no gold standard procedure for every deformity. Although residual stiffness can result from tendon transfer, overall patient satisfaction levels remain high when it is performed under the proper indications and concomitantly with other procedures to gain full correction of these challenging deformities.

Lesser Metatarsophalangeal Joint Instability: Advancements in Plantar Plate Reconstruction

The plantar plate and associated collateral ligaments are the main stabilizers of each of the lesser metatarsophalangeal joints. Although clinical examination and plain radiographs are usually sufficient to establish the diagnosis of a plantar plate tear, MRI or fluoroscopic arthrograms may help in specific cases. Recent results with a dorsal approach to plantar plate repair are promising with respect to pain relief and patient satisfaction.

Accuracy of Sonography in Plantar Plate Tears in Cadavers

OBJECTIVES

Sonography is often used in the evaluation of forefoot disorders, and its use has been suggested in the diagnosis of plantar plate tears. This study aimed to assess the accuracy of sonography in the diagnosis of plantar plate tears of the lesser digits using gross dissection as the reference standard.

METHODS

The second through fifth digits of 6 cadavers were examined with sonography to evaluate for plantar plate tears. The examination was performed by a single musculoskeletal radiologist in longitudinal and short axes, and plates were graded as torn or intact. The digits were then dissected by a single podiatrist blinded to the prior sonographic results to assess the integrity of the plates.

RESULTS

Ten plantar plates were graded as torn by sonography, all occurring in the distal plate near the phalangeal insertion. Seven of these plates were identified as torn on direct inspection. Fourteen plantar plates were found to be intact on sonography, 12 of which were intact on gross inspection. Overall, the accuracy, sensitivity, and specificity of sonography were 79.2%, 77.8%, and 80.0%, respectively. No correlation was seen between the accuracy of sonography and plate size, using plate number as a surrogate marker for plate size (P = .822).

CONCLUSIONS

Sonography is an appropriate modality in the setting of suspected plantar plate tears, with acceptable accuracy, sensitivity, and specificity. No decline in accuracy was seen with smaller plates. Thus, sonography may be especially useful when small anatomy or technical factors make magnetic resonance imaging challenging to perform and interpret.

Cadaveric Evaluation of Dorsal Intermetatarsal Approach for Plantar Plate and Lateral Collateral Ligament Repair of the Lesser Metatarsophalangeal Joints

BACKGROUND

Access to the plantar plate has been described using either a plantar approach or an extensive dorsal approach that required complete joint destabilization and often a metatarsal osteotomy. Clinical scenarios related to plantar plate tear vary and the pathologies in early stages are frequently limited to unilateral soft tissue structures; a less invasive operative approach may be possible. A novel approach requiring a release of only the lateral collateral ligament and the lateral half of the plantar plate is presented in this cadaver model; the extent of joint exposure possible is described. The ability to place a secure suture through the lateral collateral ligament and the plantar plate was analyzed.

METHODS

Nine fresh-frozen cadaveric specimens were dissected in a randomized fashion across the second to fourth metatarsophalangeal joints through the intermetatarsal space dorsally. Under distraction, soft tissue was sequentially released, including dorsal capsule, lateral collateral ligament, and the lateral half of the plantar plate. Integrity of the extensor tendons, deep transverse intermetatarsal ligament, proximal attachment of the plantar plate, and osseous structures was carefully preserved. The joint exposure was quantified after each step with sizing rods. Using a suture passer, 2-0 nonabsorbable braided sutures were passed into the lateral collateral ligament and the plantar plate, and the construct strength was measured using a tensiometer.

RESULTS

Progressive increase in mean joint exposure was noted after each step of soft tissue release with the final exposure of 6 mm after release of the lateral half of the plantar plate. Joint exposures after a capsulotomy and a lateral collateral release were 3 mm and 4 mm, respectively. Under distraction, the unilateral release of soft tissue created a lateral opening of the joint while the proximal phalangeal base adducted and medially deviated. Successful suture passage was noted in all specimens that could sustain a minimum tension of 25 N without a catastrophic failure. There was no statistically significant correlation with age, sex, foot length, and rays of the specimens when joint exposure was considered.

CONCLUSION

The dorsal intermetatarsal approach appeared to be feasible for access to the lateral collateral ligament and the lateral half of the plantar plate. The average joint exposure of 6 mm allowed a quality suture passage by a suture passer in both structures in all specimens without the need of a metatarsal osteotomy.

CLINICAL RELEVANCE

This operative approach may be appropriate for early stages plantar plate tear when only lateral soft tissue repair is needed. This technique should not preclude conversion to a more extensile operative approach or an additional metatarsal osteotomy if needed. Applicability of this operative approach in cases with more advanced pathologies or involving only medial soft tissue structures requires further studies.

Association of Abnormal Metatarsal Parabola With Second Metatarsophalangeal Joint Plantar Plate Pathology

BACKGROUND

Plantar plate pathology is common, yet it is unclear whether, and to what extent, the length of the second metatarsal contributes to this problem.

METHODS

We conducted a retrospective case-control (1:2) study to examine radiographic risk factors for plantar plate tears. One hundred patients (age 55.7 ± 12.3 years) with plantar plate injuries and 200 healthy controls (age 56.3 ± 11.3 years) were included. Cases were defined as patients with nonacute, isolated, plantar plate pathology of the second metatarsophalangeal joint confirmed by intraoperative inspection at a single foot and ankle specialty practice from June 1, 2007, to January 31, 2014. Patients presenting for pain outside of the forefoot served as the control group. Controls were matched on age (±2 years), gender, and year of presentation. Weight-bearing foot x-rays were assessed for several predetermined angular relationships by a single rater. Conditional logistic regression was used to identify risk factors for plantar plate injury.

RESULTS

A long second metatarsal, defined as a metatarsal protrusion index less than -4 mm, was the only significant risk factor for plantar plate pathology in both the univariate and multivariable analyses (multivariate odds ratio 2.5 [95% confidence interval 1.8 to 3.3], P = .002).

CONCLUSION

We found that a long second metatarsal was a risk factor for developing second metatarsophalangeal joint plantar plate tears. This knowledge may aid foot and ankle surgeons when contemplating the need for second metatarsal shortening osteotomies (eg, Weil osteotomy) during plantar plate surgery and when deciding on the amount of shortening for second metatarsal osteotomies.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

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.

Extensor Digitorum Brevis Transfer Technique to Correct Multiplanar Deformity of the Lesser Digits

Lesser digital deformities may present a surgical challenge to even the most skilled foot and ankle surgeon. Multiplanar toe deformities, including the crossover toe, are especially difficult to correct with reproducible results. Undercorrection, pain, stiffness, and recurrent deformity are well reported throughout foot and ankle literature. The goal of this article is to describe a method of correcting digital deformity utilizing the extensor digitorum brevis tendon transfer and a biotenodesis screw. The controlled tension established with the extensor tendon provides the necessary stability for multiplanar correction of multiplanar digital deformities. This technical tip article should serve as pilot study for future evaluation of this method of correction.

LEVELS OF EVIDENCE

Level IV: Case series.

How to classify plantar plate injuries: parameters from history and physical examination

Objective

To find the best clinical parameters for defining and classifying the degree of plantar plate injuries.

Method

Sixty-eight patients (100 metatarsophalangeal joints) were classified in accordance with the Arthroscopic Anatomical Classification for plantar plate injuries and were divided into five groups (0 to IV). Their medical files were reviewed and the incidence of each parameter for the respective group was correlated. These parameters were: use of high heels, sports, acute pain, local edema, Mulder's sign, widening of the interdigital space, pain in the head of the corresponding metatarsal, touching the ground, “drawer test”, toe grip and toe deformities (in the sagittal, coronal and transversal planes).

Results

There were no statistically significant associations between the degree of injury and use of high-heel shoes, sports trauma, pain at the head of the metatarsal, Mulder's sign, deformity in pronation or displacement in the transversal and sagittal planes (although their combination, i.e. “cross toe”, showed a statistically significant correlation). Positive correlations with the severity of the injuries were found in relation to initial acute pain, progressive widening of the interdigital space, loss of “touching the ground”, positive results from the “drawer test” on the metatarsophalangeal joint, diminished grip strength and toe deformity in supination.

Conclusions

The “drawer test” was seen to be the more reliable and precise tool for classifying the degree of plantar plate injury, followed by “touching the ground” and rotational deformities. It is possible to improve the precision of the diagnosis and the predictions of the anatomical classification for plantar plate injuries through combining the clinical history and data from the physical examination.

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.

Plantar plate radiofrequency and Weil osteotomy for subtle metatarsophalangeal joint instablity

Background

To the present day, literature has only discussed how to treat extensive plantar plate and collateral ligament lesions, with gross joint subluxation and obvious clinical instability. The treatment options for early stages of the disease with minor injuries and subtle instabilities have not been described. The main purpose of this prospective study is to evaluate the efficacy of the combination of the arthroscopic radiofrequency shrinkage and distal Weil osteotomy in the treatment of subtle metatarsophalangeal joint instability.

Method

Prospective data (clinical, radiological, and arthroscopic findings) of 19 patients, with a total of 35 slightly unstable joints, was collected. The physical examination defined the hypothesis for plantar plate lesions (grades 0 and 1), which was confirmed during the diagnostic step of the arthroscopic procedure.

Results

Among our patients, 73 % were females and 63 % reported wearing high heels. The average age was 59 years and post-operative follow-up was 20 months. In the initial sample frame, 62 % of joints showed spread-out toes with increased interdigital spacing. The mean American Orthopedic Foot and Ankle Society score rose from 53 points pre-operatively to 92 points post-operatively and a visual-analog pain scale average value of eight points pre-operatively decreased to zero post-operatively. During the pre-operative evaluation, none of the patients had stable joints and over 97 % were classified as having grade 1 instability (<50 % subluxation). After treatment, 83 % of the joints became stable (degree of instability 0) and over 97 % were congruent. All studied parameters showed statistically significant improvements in the post-operative period (p < 0.001) showing the efficiency of the treatment in pain relief, while restoring the joint stability and congruity.

Conclusion

Arthroscopic radiofrequency shrinkage in combination with distal Weil osteotomy promotes functional improvement, pain relief, and restores the joint stability in the plantar plate lesion grades 0 and 1.

Technique Tip: The Use of McGlamry Elevator to Assist Suture Passing in the Dorsal Technique of Plantar Plate Repair With Weil Osteotomy for Lesser Metatarsophalangeal Joint Instability

The combination of a dorsal approach to the plantar plate with a Weil's metatarsal osteotomy has been shown to provide an adequate exposure for plantar plate repair. However, soft tissues in a restricted area of the metatarsophalangeal joint could present as a technical difficulty during suture retrieval during repair of the plantar plate. The purpose of this article is to describe the use of the McGlamry elevator for assistance in the retrieval of sutures through the proximal phalanx.

LEVEL OF EVIDENCE

Level V: Expert opinion.

Positive drawer test combined with radiographic deviation of the third metatarsophalangeal joint suggests high grade tear of the second metatarsophalangeal joint plantar plate

There is uncertainty regarding the most accurate and cost-effective method for diagnosing plantar plate injuries within the foot. The purpose of this study was to examine the combined value of using clinical and radiographic findings to diagnose high grade tears (> 50% disruption) within the second metatarsophalangeal (MTP) joint. Ninety-eight consecutive patients (117 feet) who underwent corrective surgery for plantar forefoot pain at a single foot and ankle specialty clinic were included in this retrospective analysis. All patients received a structured intraoperative assessment of the second MTP joint plantar plate by a single trained observer. Twenty-five clinical and plain film radiographic variables obtained prior to surgery were tested for their association with a high grade plantar plate tear using multiple logistic regression techniques. A positive drawer sign was the most informative individual test for differentiating high from low grade tears (odds ratio [OR] = 2.9; 95% confidence interval [CI], 0.92-9.5; sensitivity 91.5%; specificity 22%). Patients with longstanding forefoot symptoms (> 2 years) tended to be more likely to have low grade tears only (OR = 2.1; 95% CI, 0.98-4.5; sensitivity 61.7%; specificity 58.1%). Most radiographic measurements did little to distinguish high from low grade tears; however, the addition of ipsilateral third MTP joint transverse deviation angle showed a trend toward improving upon the diagnostic accuracy of strategies that used clinical findings alone (area under the curve [AUC] improved from 0.63 to 0.67; P = .11). A third MTP joint deviation angle greater than 15° in either direction combined with drawer testing and duration of symptoms achieved the highest specificities of any combination of variables examined in the study (specificities 82.4% [95% CI, 73.7%-91.1%] and 89.1 [95% CI, 82.1-96.3], respectively). The combination of a positive drawer test coupled with transverse deviation of the third MTP joint (> 15°) on plain films strongly suggests an underlying high grade plantar plate tear of the second MTP joint. However, this study highlights the need for using advanced imaging to distinguish between high and low grade tears in many instances (eg, positive drawer test and normal or near-normal alignment of the third MTP joint).

LEVEL OF EVIDENCE

Diagnostic, Level II.

Prospective evaluation of protocol for surgical treatment of lesser MTP joint plantar plate tears

BACKGROUND

Instability of the lesser metatarsophalangeal (MTP) joints is a common cause of deformity and pain. The purpose of this study was to prospectively evaluate the surgical outcomes for the different grades of plantar plate tears and propose a treatment protocol.

METHODS

Sixty-eight patients (100 MTP joints) were prospectively enrolled and graded according to the anatomical grade system for plantar plate tears. Based on this classification, the appropriate surgical procedure was chosen as follows: grades 0 and I, thermal shrinkage with radiofrequency; grades II and III, direct reinsertion of the plantar plate; and grade IV, flexor-to-extensor tendon transfer. All surgical procedures were associated with a Weil metatarsal osteotomy. Evaluations were performed before and after surgical treatment with a mean follow-up of 2 years (12-36 months), using clinical and radiological parameters: American Orthopaedic Foot and Ankle Society (AOFAS) Lesser MTP-IF Scale, visual analog scale (VAS), ground touch, joint stability, and toe purchase.

RESULTS

The analysis of the clinical parameters demonstrated a significant improvement of all groups (P < .0001) after surgical treatment, but grade IV had less VAS improvement and a fair AOFAS average score (72 points). All groups improved regarding physical examination parameters, but grade I, III, and IV tears had proportionally less stable MTP joints following surgery, as well as a lower proportion of normal postoperative toe purchase and ground touch. All groups showed a significant improvement regarding radiographic parameters.

CONCLUSION

All groups of operatively treated patients had significant improvement with regard to subjective and objective parameters. Grades I, III, and IV presented inferior results compared with grades 0 and II.

LEVEL OF EVIDENCE

Level IV, case series.

Etiology and management of lesser toe metatarsophalangeal joint instability

The terms crossover toe and lesser metatarsophalangeal joint instability both describe a deterioration of the soft tissue structures that give stability to the lesser MTP joints. Initial treatment regimens focused on indirect repair of the instability without addressing the primary pathology. A staging system of the clinical examination and a grading system of the surgical findings are now available to help surgeons classify and treat the plantar plate insufficiency. Improved imaging techniques and direct surgical repair techniques through a dorsal approach have changed the treatment and possibly the results of this difficult condition.

Modification of the Weil/Maceira Metatarsal Osteotomy for Coronal Plane Malalignment During Crossover Toe Correction: Case Series

BACKGROUND

Metatarsophalangeal joint (MPJ) instability, which often involves the second ray, may result in dorsal translation and coronal drift of the proximal phalanx, with subsequent crossover of the first and second toe. After traditionally described soft tissue and osteotomy procedures are used to treat this deformity, coronal plane malalignment may persist, but few additional surgical options have been described to address this problem.

METHODS

We present a retrospective series of 5 patients who underwent a supplemental technique to augment coronal plane MPJ realignment. All patients underwent preplanned concomitant procedures. Crossover angulation of the second MPJ, amount of coronal translation required, and overall first-second ray alignment were compared pre- and postoperatively.

RESULTS

Depending on the severity of refractory deformity after soft tissue release and decompressive metatarsal osteotomy, 1.5 to 4.5 mm of coronal plane metatarsal head translation was required to achieve 3 to 20 degrees of overall valgus correction at the MPJ and complete correction of the crossover toe deformity. All patients were satisfied and had good function at last follow-up, a mean of 10.2 months, although 3 patients exhibited some level of second MPJ stiffness. One patient ended up with a component of residual floating toe deformity that was considered more of an incomplete correction of dorsal MPJ subluxation rather than any technical complication of this translational osteotomy modification designed to primarily correct coronal plane malalignment. A second patient had asymptomatic angular malalignment through partial (coronal plane) malrotation of the metatarsal osteotomy before it had healed.

CONCLUSIONS

We have found this technique modification to be a very effective and simple means of treating recalcitrant lesser MPJ coronal plane malalignment when traditional soft tissue and bony techniques fail to fully restore anatomic MPJ position.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Correction of multiplanar deformity of the second toe with metatarsophalangeal release and extensor brevis reconstruction

BACKGROUND

Surgical treatment of multiplanar (varus and dorsal angulation) second toe deformities due to degenerative instability can lead to recurrence, stiffness, and pain. The goal of this study was to evaluate the short-term outcomes associated with a new technique using an extensor digitorum brevis (EDB) tendon reconstruction to correct such deviation of the second metatarsophalangeal (MTP) joint.

METHODS

Ten patients (10 female, 0 male) with 11 operated second toes having undergone correction with a reconstruction using the EDB tendon were assessed at an average of 18.5 months (range, 12-34) after surgery. The technique was indicated when MTP and medial partial plantar plate release alone were not sufficient to correct multiplanar deformity. Radiographic parameters (AP and lateral metatarsal-proximal phalanx angles), physical exam (MTP joint range of motion), and subjective outcomes (the Foot and Ankle Outcome Score [FAOS]) were assessed. A toe-specific survey captured more detailed subjective information, including patient satisfaction.

RESULTS

Preoperatively, the average MTP joint angle was 4.5 degrees in the varus direction, which changed to 14.2 degrees in the valgus direction postoperatively. On exam, the average MTP joint range of motion was 60.9 ± 11.6 degrees dorsiflexion and 11.1 ± 2.5 degrees plantarflexion. Postoperative FAOS scores demonstrated an average of 89.9 ± 9.8 for the symptoms domain. In all, 9 of 11 patients were either highly satisfied or moderately satisfied (none dissatisfied).

CONCLUSION

With the stated limitations, the EDB tendon reconstruction technique described in conjunction with collateral ligament and partial plantar plate release provided powerful correction. Minimal release of the medial plantar plate and not overtightening the reconstruction are recommended to avoid shifting the toe in the opposite direction.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Clinical examination of plantar plate abnormality: a diagnostic perspective

BACKGROUND

Plantar plate tears can cause pain and deformity in the forefoot but are frequently missed on initial examination. The purpose of this article was to evaluate the diagnostic statistics of common clinical examination parameters using observed intraoperative abnormality as the referenced standard.

METHODS

Medical records of 90 patients (109 feet) who underwent a plantar plate repair were reviewed for the presence and onset of pain, plantar edema, instability of the second metatarsophalangeal (MTP) joint (drawer sign), pain with range of motion of the lesser MTP joint, first MTP joint range of motion, crossover toes, previous first ray surgery, and previous corticosteroid injections. Clinical examination findings were compared with intraoperative findings. Diagnostic statistics were calculated.

RESULTS

Parameters with a high sensitivity (greater than 80%) were gradual onset of pain (93%), previous first ray surgery (100%), pain at the second metatarsal head (98%), edema at the second metatarsal head (95.8%), and a positive drawer sign (80.6%). High specificity (greater than 80%) was found for a positive drawer test (99.8%) and crossover toes (88.9%). Parameters with odds ratios greater than 1 were gradual onset of pain (1.104), pain at the second metatarsal head (6.125), edema at the second metatarsal head (2.875), and a positive drawer sign (1.389).

CONCLUSION

Ninety-five percent of patients with a plantar plate tear presented with a gradual onset of forefoot pain, edema, and a positive drawer sign. A comprehensive clinical examination can heighten the suspicion for plantar plate tears when the data are interpreted correctly.

LEVEL OF EVIDENCE

Level III, retrospective, diagnostic.

Metatarsophalangeal joint instability of the lesser toes

Metatarsophalangeal joint instability of the lesser toes is a common finding and a common cause of metatarsalgia. The clinical presentation can include swelling without digital deformity; however, often, this can progress to the development of coronal and transverse plane malalignment. In some cases, frank metatarsophalangeal joint dislocation can develop. The treatment regimen has historically focused on indirect surgical realignment using soft tissue release, soft tissue reefing, tendon transfers, and periarticular osteotomies. An improved understanding of the plantar plate has recently led to the development of a clinical staging system and surgical grading system of plantar plate attenuation. A dorsal surgical approach, using a Weil osteotomy, allows the surgeon to directly access and repair or advance the plantar plate to the base of the proximal phalanx. The addition of direct plantar plate repair could be a significant advancement in the reconstruction and realignment of metatarsophalangeal joint instability.

The underlying osseous deformity in plantar plate tears: a radiographic analysis

PURPOSE

Plantar plate tears can cause pain and deformity of the forefoot. The purpose of this study is to correlate common radiographic findings with observed intra-operative pathology in patients with plantar plate pathology.

METHODS

Bilateral weight-bearing radiographs were reviewed for 88 patients (106 feet) who underwent surgical repair of suspected plantar plate pathology. Parameters reviewed included the first intermetatarsal angle, the metatarsus adductus angle, the second and third metatarsophalangeal angles, splaying of the second and third toes, evaluation of the metatarsal parabola by 3 different methods, the first and second lateral declination angles, and the second lateral metatarsophalangeal angle.

RESULTS

Of 106 feet, 97 had intra-operative plantar plate tears. The radiographs of patients with plantar plate tears had an increased amount of digital splay on the anteroposterior radiograph compared to patients without pathology. For patients with unilateral plantar plate pathology, the metatarsal parabola of the symptomatic foot was compared with that of the asymptomatic foot. A significantly increased second metatarsal protrusion distance as measured by 2 different methods was noted in the symptomatic foot. Odds ratios revealed that patients with an intermetatarsal angle >12, medial deviation of the second toe, and splaying of the digits were more likely to be diagnosed with a plantar plate tear intra-operatively.

CONCLUSION

Although radiographs do not definitively diagnose plantar plate tears, understanding osseous forefoot architecture will aid with diagnosis in the absence of other osseous pathology. Furthermore, these data suggest that parabola should be corrected to maintain long-term correction of plantar plate pathology.

LEVEL OF EVIDENCE

Prognostic, Level II.

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.

Surgical treatment approaches to second metatarsophalangeal joint pathology

The second metatarsophalangeal joint is prone to specific and varied pathology that is well understood and may exist in isolation or in combination with other forefoot abnormality. Surgical treatment options for managing end-stage second metatarsophalangeal abnormalities have been minimally studied and exist primarily in case studies and series in the literature. As a result, surgical approaches remain controversial and warrant further discussion.