MR imaging of disorders of the posterior tibialis tendon

Two-Dimensional and 3-Dimensional MRI Assessment of Progressive Collapsing Foot Deformity-Adult Acquired Flat Foot Deformity

This article is meant to serve as a reference for radiologists, orthopedic surgeons, and other physicians to enhance their understanding of progressive collapsing foot deformity, also known as adult acquired flat foot deformity. Pathophysiology, imaging findings, especially on MRI and 3-dimensional MRI are discussed with relevant illustrations so that the readers can apply these principles in their practice for better patient managements.

The morphometry of distal tibia and posterior malleolus and its clinical implications in total ankle prosthesis

PURPOSE

The aim of this study is to reveal the morphometry of the distal tibia and posterior malleolus and to generate morphometric reference data for the tibial component of total ankle prosthesis.

METHODS

This study was performed on 121 human dry tibiae (47 right, 74 left). The morphometric measurements of distal tibial structures, tibial length and the distance between the medial and posterior malleolus were measured in this study. Measurements on 44 tibiae were repeated three times and averaged for minimizing intra-observer error.

RESULTS

The tibial length was found 34.19 ± 2.31 cm. Mean values of width of fibular notch at tibial plafond and 10 mm proximal to the tibial plafond were 25.71 ± 2.44 mm and 17.81 ± 2.46 mm, respectively. Mean depth of fibular notch at tibial plafond and 10 mm proximal to the tibial plafond were 3.60 ± 1.04 mm and 3.37 ± 1.24 mm, respectively. Mean height of fibular notch was found 48.21 ± 10.51 mm. Mean width and height of medial malleolus were 25.08 ± 2.13 mm and 14.73 ± 1.85 mm, respectively. Mean width and length of tibial plafond were 27.71 ± 2.74 mm and 26.96 ± 2.62 mm, respectively. Mean values of width and height of posterior malleolus were measured 21.41 ± 3.26 mm and 6.74 ± 1.56 mm, respectively. Mean distance between medial and posterior malleolus was found 37.17 ± 3.53 mm. Mean width and depth of malleolar groove were 10.26 ± 1.84 mm and 1.73 ± 0.75 mm, respectively. The mean intra-class correlation values were found between the 0.959 and 0.999.

CONCLUSIONS

Knowing the distal tibial morphometry is crucial for designing convenient ankle replacement implants for Turkish population. To our knowledge, this study is the first in the literature that identifies posterior malleolar morphometry on dry tibiae. We believe that this study will make a significant contribution to the literature about distal tibial morphometry and especially the posterior malleolus and the data of our study can be used for designing total ankle prosthesis in Turkish population.

Differential Diagnosis of Charcot Neuroarthropathy in Subacute and Chronic Phases: Unusual Diseases

Charcot Neuroarthropaty (CN) is a complication of diabetes with devastating consequences as it produces severe deformities in the foot developing in recurrent ulcers that rise the probability of amputation. There are several diseases mentioned in the literature that have to be considered for the differential diagnosis of CN, often related to the acute phase (gout, ankle sprain, inflammatory arthritis, cellulitis, venous thrombosis) but there is paucity of information related to the differential diagnosis in later stages (coalescence, remodeling) when there is deformity of the foot. Clinicians and diabetologists are not familiarized with orthopedic pathology and do not have in mind certain diseases that could mimic CN in the subacute or chronic phases and this can develop in a wrong diagnosis. It is important to make a correct diagnosis in patients with suspected CN not only in the acute phase but also in the chronic phase to establish an accurate treatment. This article is a review of the differential diagnosis of CN in subacute and chronic phases showing similarities and differences that can help clinicians and diabetologists to make an accurate diagnosis and treatment. We describe unusual diseases like tendon and muscles disorders, Frieberg's disease, complex pain regional syndrome, transient regional osteoporosis and osteomyelitis superimposed to CN and the main features of each one that could help in making a differential diagnosis.

Effects of Preoperative Abnormality of Posterior Tibial Tendon on the Surgical Outcomes of Medial Osteochondral Lesion of the Talus

BACKGROUND

Although surgical treatment for osteochondral lesion of the talus (OLT) can obtain good clinical outcomes, the rate of return to sports is variable. It is reported that medial OLT unrelated to trauma has abnormal structures in the medial aspect, which may induce the medial OLT due to the medial instability. The posterior tibial tendon (PTT) plays an important role in the stabilization of the foot, and high mechanical stress may be added to the PTT to compensate for medial instability in medial OLT. We investigated whether abnormal PTT findings on preoperative magnetic resonance imaging (MRI) in patients with OLT affect clinical outcomes after surgery.  Methods: Eighty-one ankles in 74 patients who were treated surgically for OLT were included in this study (41 men and 33 women; mean age, 26.0 years). Abnormalities of the PTT were evaluated using preoperative MRI. The Japanese Society for Surgery of the Foot (JSSF) scale, arch height, and ankle activity score (AAS) on standing plain radiogram were compared between patients with and those without preoperative PTT abnormalities.

RESULTS

Twenty-five ankles (30.9%) had PTT abnormalities on preoperative MRI. All patients with preoperative PTT abnormalities were medial OLT. There were no significant differences in the preoperative JSSF scale in the procedures for OLT. The postoperative JSSF scale and arch height were significantly lower in patients with preoperative PTT abnormalities than those without them. AAS in patients with preoperative abnormalities significantly decreased at the final follow-up.  Conclusion: PTT abnormalities on preoperative MRI may affect clinical outcomes even in preoperative asymptomatic patients in the medial OLT unrelated to trauma.

Tibial Retro-Malleolar Groove Morphology in Patients With Posterior Tibialis Tendon Dysfunction

The posterior tibial tendon is a gliding tendon which courses around the medial malleolus and fails in posterior tibialis tendon dysfunction (PTTD) leading to a flat foot deformity. Distal tibial bone spurs have been identified as a secondary sign of PTTD although they have not been quantified in detail. The aim of this study was to assess the association of tendon dysfunction with the bony morphology of the tibial retro-malleolar groove. We performed a retrospective review of the clinical presentation, plain radiographs, and 103 magnetic resonance imaging (MRI) scans in 82 consecutive patients with PTTD compared with a non-PTTD group. We carried out a quantitative and qualitative assessment of the presence of plain radiographic bone spurs, stage of PTTD and MRI imaging of the morphology of the tibial bony malleolar groove. Plain radiographic bone spurs, as a secondary sign of PTTD, were present in 21.3% of ankle radiographs. MRI bone spurs were identified in 26/41 (63.4%) for all high-grade partial and complete tears and 7/41 (17.1%) for isolated complete tears compared with only 3.9% of the non-PTTD group. There was a significant association between the presence of bone spurs on MRI imaging and high-grade partial and complete tibialis posterior tears (p < .001; odds ratio of 4.98). Eleven of 103 (10.7%) of spurs were large and in 4/103 (3.9%) were substantial enough to create a tunnel-like hypertrophic groove not previously reported. There is variation in the bony structure of the malleolar groove in PTTD not observed in the non-PTTD group. Further investigation over time may elucidate whether the groove morphology may lead to mechanical attrition of the tibialis posterior tendon and contribute to failure of healing and progressive tendon degeneration.

Two-Dimensional and 3-Dimensional MRI Assessment of Progressive Collapsing Foot Deformity-Adult Acquired Flat Foot Deformity

This article is meant to serve as a reference for radiologists, orthopedic surgeons, and other physicians to enhance their understanding of progressive collapsing foot deformity, also known as adult acquired flat foot deformity. Pathophysiology, imaging findings, especially on MRI and 3-dimensional MRI are discussed with relevant illustrations so that the readers can apply these principles in their practice for better patient managements.

Presurgical Perspective and Postsurgical Evaluation of Non-Achilles Tendons of the Ankle and Retinaculum

The vast majority of non-Achilles ankle tendinopathies are related to overuse. This article discusses the clinical aspect, imaging appearance, and management of tendinopathies of the lateral, medial, and the anterior compartments with a focus on presurgical perspective and postsurgical evaluation.

Sonographic finding of medial ankle subcutaneous edema and its association with posterior tibial tenosynovitis

Background:

To evaluate if the sonographic finding of medial ankle subcutaneous (subQ) edema is associated with posterior tibial tenosynovitis (PTTS).

Methods:

Sonographic images of the medial ankle soft tissues from 40 patients with PTTS and 37 patients with a normal posterior tibial tendon (PTT) were randomized and independently evaluated by two musculoskeletal radiologists for the presence or absence of subQ edema. Both radiologists were blinded to the images and status of the PTT and the patient's history. Statistical analyses included the Chi-square test and Cohen's Kappa statistics for inter-observer agreement.

Results:

A statistically significant association was seen for the presence of medial ankle subQ edema and PTTS among both radiologists’ findings. Of the 40 patients with PTTS, 33 (82.5%) were found positive by the first radiologist for medial ankle subQ edema, while no subQ edema was found in 28 of the 37 (75.7%) patients with a normal PTT (P < 0.001). Similarly, the second radiologist found that 33 of the 40 (82.5%) with PTTS were positive for subQ edema, while no subQ edema was found in 24 of the 37 (64.9%) patients with a normal PTT (P < 0.001). There was also substantial inter-observer agreement between the 2 radiologists (κ-value = 0.79; 95% confidence intervals: 0.65, 0.93).

Conclusion:

A statistically significant association was present for the association of the sonographic finding of medial ankle subQ edema and the presence of PTTS. Further studies could evaluate if the sonographic finding of medial ankle subQ edema is an early predictor of PTT dysfunction.

How to Report: Ankle MRI

Reporting ankle magnetic resonance imaging involves the assessment of multiple joints, tendons, and ligaments in several planes and numerous sequences. This article describes an approach using four anatomical categories (subcutaneous fat, bones and joints, tendons, and ligaments) to simplify and improve reporting efficiency. The main pathologies are covered, emphasizing the specific features to comment on, as well as suggesting terminology and phrases to use when reporting.

Foot and ankle functions and deformities focus on posterior tibial tendon dysfunction using magnetic resonance imaging in patients with rheumatoid arthritis

OBJECTIVES

Posterior tibial tendon dysfunction (PTTD) affects the support of the medial longitudinal arch and stability of the hindfoot. The purpose of this study was to assess the relationships of PTTD with foot and ankle functions and foot deformities in patients with rheumatoid arthritis (RA).

METHODS

A total of 129 patients (258 feet) who underwent magnetic plain and contrast-enhanced magnetic resonance imaging were enrolled in this study. Positive magnetic resonance imaging findings were defined as tenosynovitis and incomplete and complete rupture of the posterior tibial tendon. Foot and ankle functions were assessed using the Japanese Society for Surgery of the Foot standard rating system for the RA foot and ankle scale (JSSF-RA) and self-administered foot evaluation questionnaire. Plain radiographs were examined for the hallux valgus angle, first metatarsal and second metatarsal angle, lateral talo-first metatarsal angle, and calcaneal pitch angle.

RESULTS

PTTD was associated with motion in the JSSF-RA (p = .024), activities of daily living in JSSF-RA (p = .017), and pain and pain-related factors in the self-administered foot evaluation questionnaire (p = .001). The calcaneal pitch angle was significantly lower in the feet with PTTD than in those without PTTD (median: 16.2° vs. 18.0°; p = .007).

CONCLUSIONS

The present study shows that PTTD was associated with foot and ankle functions and flatfoot deformity. Thus, a better understanding of PTTD in patients with RA is important for the management of foot and ankle disorders in clinical practice.

3-T MRI of the Ankle Tendons and Ligaments

Ankle sprain is the most common injury in athletic populations. Ligament and tendon pathologies of the ankle are common, ranging from traumatic injuries to degeneration leading to chronic pain and acquired foot deformities. MRI is the imaging modality of choice to evaluate tendon and ligament pathology of the ankle, specifically derangements of tendons and ligaments. 3-T MRI offers improved imaging characteristics relative to 1.5-T MRI, allowing for better delineation of anatomic detail and pathology. This article provides a review of the anatomy and common pathologies of the ankle ligaments and tendons using high-resolution 3-T MRI.

The awareness of hindfoot malalignment on non-weight-bearing ankle MRI

OBJECTIVE

Hindfoot malalignment is a relatively common clinical finding and several studies have suggested that hindfoot valgus can be identified on non-weight-bearing ankle MRI. The aim of this study was to determine the awareness of hindfoot malalignment on ankle MRI amongst consultant musculoskeletal radiologists.

MATERIALS AND METHODS

All MRI studies referred by Foot and Ankle Unit Consultants reported by one of 14 consultant musculoskeletal radiologists between March 2016 and August 2019 were retrieved from the Hospital Radiology Information System. These were reviewed independently by a radiology fellow and a consultant radiologist. Tibiocalcaneal angle (TCA) was measured, and extra-articular talocalcaneal (EA-TCI) and calcaneofibular impingement (EA-CFI) were recorded. Radiology reports were then analysed for mention of hindfoot malalignment and the presence of EA-TCI and EA-CFI.

RESULTS

The study group comprised 129 patients, 46 males and 83 females with a mean age of 46.8 years (range 8-84 years). Based on review, hindfoot valgus was present in 78-80 cases (60.5-62%), EA-TCI in 30-36 cases (23.2-27.9%) and EA-CFI in 18-21 cases (14-16.3%). By comparison, MRI reports mentioned hindfoot valgus in 18 cases (2 incorrectly), EA-TCI in 8 cases (1 incorrectly) and EA-CFI in 10 cases (1 incorrectly).

CONCLUSION

Hindfoot valgus, EA-TCI and EA-CFI were present relatively commonly on review of ankle MRI studies in patients referred from a specialist Foot and Ankle Unit but were commonly under-reported highlighting a relative lack of awareness of hindfoot malalignment on ankle MRI amongst musculoskeletal radiologists, which could impact negatively on patient management.

Ultrasound Imaging Is Reliable for Tibialis Posterior Size Measurements

OBJECTIVES

The tibialis posterior (TP) is a vital muscle for controlling the medial longitudinal arch of the foot during weight-bearing activities. Dysfunction of this muscle is associated with a variety of pathologic conditions; thus, it is important to reliably assess its morphologic characteristics. Ultrasound (US) has been used to assess characteristics of TP tendons but not the muscle cross-sectional area (CSA). The purpose of this study was to establish a reliable US technique to measure the TP CSA and thickness.

METHODS

Twenty-three healthy volunteers participated. We evaluated the CSA and thickness at 4 measurement locations (anterior and posterior views at both 30% and 50% of the shank length).

RESULTS

The participants included 12 female and 11 male volunteers (mean age ± SD, 31.23 ± 14.93 years). Excellent reliability was seen for the CSA and thickness at all locations (intraclass correlation coefficients, 0.988-0.998). Limits of agreement (LoA) and standard errors of the measurement (SEMs) were slightly lower at the 30% locations (LoA at 30%, 4.6-9.2; LoA at 50%, 6.4-9.7; SEM at 30%, 0.03-0.05; SEM at 50%, 0.04-0.07). Strong correlations were seen between anterior and posterior measurements of the CSA (30%, r = 0.99; P < .0001; 50%, r = 0.94; P < .0001) and thickness (30%, r = 0.98; P < .0001; 50%, r = 0.95; P = .0001).

CONCLUSIONS

Based on these results, the TP can be measured accurately with US at any of the tested locations. Due to the ease of collection and the quality of the data, we recommend the anterior view at 30% of the shank length to measure the CSA. The ability to assess muscle size of the TP will aid in a variety of medical and research applications.

[Etiology, pathogenesis, clinical features, diagnostics and conservative treatment of adult flatfoot]

BACKGROUND

On average, one in six adults is affected by an acquired flatfoot. This foot deformity is characterized by its progression of stages and in 10% of cases causes complaints that require treatment. Untreated, the loss of walking ability may result in the final stage. Correct staging is crucial to being able to offer a specific course of therapy including a wide spectrum of conservative and operative treatments.

MATERIAL AND METHODS

This review is based on pertinent publications retrieved from a selective search in PubMed and Medline and on the authors' clinical experience.

DIAGNOSTICS

The loss of function of static (spring ligament complex) and dynamic (tibialis posterior tendon) stabilizers causes the characteristic deformity with loss of the medial arch, hind foot valgus and forefoot abduction. In the late stage, severe secondary osteoarthritis in upper and lower ankle joints occurs and impedes walking ability. The essential physical examination is supplemented by weight-bearing dorsoplantar and lateral radiographs, which provide further information about axial malalignment (Meary's angle, Kite's angle). The long axis hind foot view allows analysis of the hindfoot valgus. MRI provides further information about the integrity of the tibialis posterior tendon, spring ligament complex and cartilage damage.

THERAPY

The therapy aims to reduce pain, regain function and avoid development of secondary osteoarthritis and degenerative tendon disorders. Progress of the deformity should be stopped. Therefore, the main aspects of the deformity-loss of medial arch, hindfoot valgus and forefoot abduction should be addressed and corrected. In the acute phase, tendovaginitis of the tibialis posterior tendon can be treated sufficiently by anti-inflammatory measures, relieving mechanical loads on the tendon and muscle and physiotherapy.

Adult Acquired Flatfoot Deformity: Anatomy, Biomechanics, Staging, and Imaging Findings

Adult acquired flatfoot deformity (AAFD) is a common disorder that typically affects middle-aged and elderly women, resulting in foot pain, malalignment, and loss of function. The disorder is initiated most commonly by degeneration of the posterior tibialis tendon (PTT), which normally functions to maintain the talonavicular joint at the apex of the three arches of the foot. PTT degeneration encompasses tenosynovitis, tendinosis, tendon elongation, and tendon tearing. The malaligned foot is initially flexible but becomes rigid and constant as the disorder progresses. Tendon dysfunction commonly leads to secondary damage of the spring ligament and talocalcaneal ligaments and may be associated with injury to the deltoid ligament, plantar fascia, and other soft-tissue structures. Failure of multiple stabilizers appears to be necessary for development of the characteristic planovalgus deformity of AAFD, with a depressed plantar-flexed talus bone, hindfoot and/or midfoot valgus, and an everted flattened forefoot. AAFD also leads to gait dysfunction as the foot is unable to change shape and function adequately to accommodate the various phases of gait, which require multiple rapid transitions in foot position and tone for effective ambulation. The four-tier staging system for AAFD emphasizes physical examination findings and metrics of foot malalignment. Mild disease is managed conservatively, but surgical procedures directed at the soft tissues and/or bones become necessary and progressively more invasive as the disease progresses. Although much has been written about the imaging findings of AAFD, this article emphasizes the anatomy and function of the foot's stabilizing structures to help the radiologist better understand this disabling disorder. Online supplemental material is available for this article. ^©RSNA, 2019.

The horizontal calcaneofibular ligament: a sign of hindfoot valgus on ankle MRI

OBJECTIVE

Hindfoot valgus malalignment has been assessed on coronal MRI by the measurement of the tibio-calcaneal (TC) angle and apparent moment arm (AMA). This study aimed to determine if the calcaneofibular ligament (CFL) angle could be used as a further marker of hindfoot valgus malalignment on routine non-weight-bearing ankle MRI.

MATERIAL AND METHODS

One hundred ninety-five consecutive 3-T ankle MRI studies were identified from the hospital PACS system. The TC and CFL angles could be measured in 155 cases (78%), and the AMA on 153 cases.

RESULTS

The study group comprised 56 males and 72 females with a mean age of 46 years (range 4-89 years). In 27 patients, both ankles had been imaged. The Pearson correlation between the TC and CFL angles was -0.43, with a corresponding p value of 0.001 indicating a strong negative correlation between the TC and CFL angles. The CFL angle was significantly lower in those with hindfoot valgus (113 ± 14) compared with those without (123° ± 15°) (p = 0.001). The optimal cut-off point of the CFL angle for hindfoot valgus was ≤119°, with a sensitivity and specificity of 66% and 63% respectively. The Pearson correlation between the CFL angle and AMA was -0.10, with a corresponding p value of 0.21 indicating a weak negative correlation that did not reach statistical significance.

CONCLUSION

Hindfoot valgus as estimated by the increased TC angle on coronal non-weight-bearing ankle MRI is associated with a reduced CFL angle on sagittal MR images, but is not associated with AMA. Therefore, a horizontal orientation of the CFL on sagittal MR images may be a further useful sign of hindfoot valgus.

Fluid around the distal tibialis posterior tendon on ankle MRI: prevalence and clinical relevance

OBJECTIVE

It has been stated that the distal 1-2 cm of the tibialis posterior tendon (TPT) does not have a tendon sheath but rather a paratenon, and that any fluid seen around this segment on ankle MRI is considered to represent paratendonitis. The prevalence and clinical significance of isolated TPT paratendonitis diagnosed on ankle MRI is unknown. This study aims to correlate the presence of isolated distal segment TPT paratendonitis on ankle MRI, with the presence or absence of medial midfoot pain.

METHODS

A retrospective database of 195 consecutive 3 T ankle MRI studies was assessed for the presence of isolated TPT paratendonitis. Relevant clinical notes were available in 159 of these cases, and were reviewed for the absence or presence of medial midfoot pain.

RESULTS

Of 133 patients with both ankle MRI studies and clinical notes available, 53 (33.3%) patients had isolated TPT paratendonitis based on MRI. Of these, 37 (69.8%) had reported no medial foot pain on review of clinical records, while medial foot pain was recorded in 16 cases (30.2%). The comparison of TPT paratendonitis with clinically evident medial midfoot pain showed no statistically significant association (p = 0.19).

CONCLUSION

Fluid signal intensity around the distal 1-2 cm of the TPT is a relatively common finding on ankle MRI. Therefore, care should be taken when reporting ankle MRI studies not to overstate the relevance of this finding.

ADVANCES IN KNOWLEDGE

There was no statistically significant relationship between medial midfoot pain and the presence of isolated TPT paratendonitis.

T2* mapping and subregion analysis of the tibialis posterior tendon using 3 Tesla magnetic resonance imaging

OBJECTIVE

Early detection of tibialis posterior tendon changes and appropriate intervention is necessary to prevent disease progression to flat-foot deformity and foot/ankle dysfunction, and the need for operative treatment. Currently, differentiating between early-stage tibialis posterior tendon deficiency patients who will benefit from conservative vs more aggressive treatment is challenging. The objective of this work was to establish a quantitative MRI T2* mapping method and subregion baseline values in the tibialis posterior tendon in asymptomatic ankles for future clinical application in detecting tendon degeneration.

METHODS

26 asymptomatic volunteers underwent T2* mapping. The tendon was divided axially into seven subregions. Summary statistics for T2* within each subregion were calculated and compared using Tukey post-hoc pairwise comparisons.

RESULTS

Results are reported for 24 subjects. The mean tibialis posterior tendon T2* was 7 ± 1 ms. Subregion values ranged from 6 ± 1 to 9 ± 2 ms with significant between-region differences in T2*. Inter- and intrarater absolute agreement intraclass correlation coefficient (ICC) values were all "excellent" (0.75 < ICC=1.00) except for regions 5 through 7, which had "fair to good" interrater and/or and intrarater ICC values (0.4 < ICC=0.75).

CONCLUSION

A tibialis posterior tendon T2* mapping protocol, subregion division method, and baseline T2* values for clinically relevant regions were established. Significant differences in T2* were observed along the tendon length.

ADVANCES IN KNOWLEDGE

This work demonstrates that regional variation exists and should be considered for future T2*-based research on posterior tibias tendon degeneration and when using T2* mapping to evaluate for potential tibialis posterior tendon degeneration.

Tenosynovial fluid as an indication of early posterior tibial tendon dysfunction in patients with normal tendon appearance

OBJECTIVE

Our primary aim was to quantify the posterior tibial tendon (PTT) sheath fluid volume in individuals with the clinical diagnosis of stage 1 posterior tibial tendon dysfunction (PTTD) and no MRI-detectable intra-substance tendon pathology and compare them with patients with other causes of medial ankle pain, also without MRI-detectable intra-substance PTT pathology and with normal controls. We also wanted to determine if there is a fluid measurement that correlates with the clinical diagnosis of PTTD.

MATERIALS AND METHODS

A total of 326 individuals with medial ankle pain and no intra-substance PTT pathology were studied. Group 1 included 48 patients with a clinical diagnosis of stage 1 PTT dysfunction, group 2 comprised 278 patients with other causes of medial ankle pain, and a third control group consisted of 56 patients without any medial ankle pain. MRI-based geometric measurements included PTT fluid volume, maximum cross-sectional fluid area, and fluid width. Fluid measurements were compared between groups and measurement reliability was tested.

RESULTS

Group 1 showed greater PTT fluid volume, area, and width compared with groups 2 (other causes of medial ankle pain) and 3 (asymptomatic controls) (all p values < 0.001). A 9-mm threshold maximum fluid width was associated with PTTD (sensitivity 84%, specificity 85%). Measurements were reliable (all p values < 0.03) among three observers blinded to the gold standard.

CONCLUSION

Patients with stage 1 PTT dysfunction displayed greater volumes of tendon-sheath fluid than those with other causes of medial ankle pain and compared with asymptomatic controls. A threshold maximum fluid width greater than or equal to 9 mm distinguishes those with PTTD. An association between tendon sheath fluid distension and the clinical diagnosis of stage 1 posterior tibial tendon disease in the setting of no MRI-detectable intra-substance tendon pathology may allow for differentiation of medial ankle pain from other sources and may allow for early intervention aimed at preventing progressive PTTD. The level of evidence was prognostic (level III).

Sonographic and radiographic findings of posterior tibial tendon dysfunction: a practical step forward

The purpose of this article is to describe the sonographic and radiographic findings in the diagnosis and treatment of posterior tibial tendon dysfunction. Ultrasound and radiographs play a crucial role in the diagnosis of posterior tibial tendon dysfunction and in imaging the postoperative changes related to posterior tibial tendon dysfunction. Early detection and diagnosis of posterior tibial tendon dysfunction is important in helping to prevent further progression of disease, obviating the need for more invasive and complex procedures.

Imaging of the Tibionavicular Ligament, and Its Potential Role in Adult Acquired Flatfoot Deformity

BACKGROUND

The spring ligament is an important medial arch stabilizer. However, when disrupted, it does not cause planovalgus deformity until the foot is cyclically loaded. We propose that the tibionavicular (TN) ligament plays an important role. However, this ligament is not imaged in routine magnetic resonance imaging (MRI) sequences.

METHODS

A prospective case-control study using a novel MRI sequence to image the TN ligament in 20 normal feet creating a baseline appearance of the ligament. We then scanned 20 patients with adult acquired flatfoot deformity (AAFD). All patients had weightbearing anteroposterior and lateral radiographs. We followed up patients, the end point being surgery or 18 months' follow-up.

RESULTS

The normal ligament was reliably identified on the novel sequences. It had a reproducible appearance in 2 views, and consistent length and width. Two groups of patients were identified in the AAFD cohort: Normal TN (11/20) (The mean Meary angle was 6.8 degrees) and Abnormal TN (9/20). The ligament was thickened proximally, with distal attenuation and intrasubstance edema. On sagittal sequence, it had dorsal bulging and high signal. The mean Meary angle was 13.2 degrees ( P = .013). All patients had posterior tibial tendon dysfunction and 8 had spring ligament complex attenuation. Five patients have undergone corrective surgery compared to none in the other group.

CONCLUSION

This study adds to the evidence that AAFD is multifactorial. With this imaging technique, we were able to reliably image the TN ligament. We hope that including this sequence into routine scanning will help us understand its role in flatfoot deformity. This poses the question of whether this structure will play a role in reconstructive surgery in future.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Posterior tibial tendon dysfunction: Clinical and magnetic resonance imaging findings having histology as reference standard

OBJECTIVE

To investigate the correlation between MRI, clinical tests, histopathologic features of posterior tibial tendon (PTT) dysfunction in patients with acquired adult flatfoot deformity surgically treated with medializing calcaneal osteotomy and flexor digitorum longus tendon transposition.

MATERIALS AND METHODS

Nineteen patients (11 females; age: 46 ± 15 year, range 18-75) were pre-operatively evaluated using the single heel rise (HR) and the first metatarsal rise (FMR) sign tests. Two reviewers graded the PTT tears on a I-III scale and measured the hindfoot valgus angle on the pre-operative MRI of the ankle. The specimens of the removed portion of PTT were histologically analysed by two pathologists using the Bonar and Movin score. Linear regression, Spearman's rank-order, and intraclass correlation coefficient (ICC) statistics were used.

RESULTS

ICC for MRI was excellent (0.952). Correlation between FMR and HR tests was at limit of significance (r = 0.454; P = 0.051). The HR and FMR tests were significantly correlated to the Movin score (r = 0.581; P = 0.009 and r = 0.538; P = 0.018, respectively) and were not significantly correlated to the Bonar score (both with a r = 0.424; P = 0.070). PTT tendinopathy grading at MRI was significantly correlated to the FMR test (p = 0.041) but not to the hindfoot valgus angle (p = 0.496), the HR test (p = 0.943), the Bonar score (p = 0.937), and the Movin score (p = 0.436). The hindfoot angle was not correlated to any of the other variables (p > 0.264).

CONCLUSION

For PTT dysfunction, there is high correlation between HR and FMR test and histology evaluated using the Movin score, while no correlation was seen for the Bonar score. Semiquantitative grading of PTT dysfunction at MRI only correlates to the FMR and not to histology. The hindfoot valgus angle is not correlated to any of the considered variables.

Unilateral Dislocation of the Posterior Tibialis Tendon (PTT) and Flexor Digitorum Longus Tendon With Contralateral PTT Subluxation in a Patient With Congenitally Shallow Flexor Groove

INTRODUCTION

Flexor tendon dislocation from the flexor tendon groove posterior of the medial malleolus has been previously described, and may be difficult to diagnose initially, but is amendable to surgical treatment with good outcomes. We present a unique case of unilateral dislocation of the posterior tibialis and flexor digitorum longus tendons with contralateral flexor digitorum longus subluxation that was treated surgically with a good outcome.

CASE PRESENTATION

A 37-year-old active duty male sustained a dislocation and subluxation of the flexor tendons bilaterally after a forced dorsiflexion injury. Bilateral ankle magnetic resonance imaging revealed the injuries that this patient sustained and aided in surgical planning. Surgical Treatment. Bilateral flexor tendon groove deepening with periosteal flap elevation and retinacular repair.

DISCUSSION/CONCLUSION

This injury has not been previously described in the literature after a forced dorsiflexion mechanism. Advanced imaging is helpful as this injury may be initially misdiagnosed. This case shows that delayed bilateral reconstruction of the flexor tendon grooves and retinacula are reliable methods for pain relief to allow a patient to return to a physically demanding level of function.

LEVELS OF EVIDENCE

Level V.

Postoperative Repeat Dislocation of the Posterior Tibial Tendon: A Case Report

Dislocation of the posterior tibial tendon is an uncommon condition. Although surgery is usually performed in most cases of posterior tibial tendon dislocation, postoperative repeat dislocation of the posterior tibial tendon has not been reported in the published data. We report the case of a 27-year-old male patient who experienced repeat dislocation of the posterior tibial tendon after a gymnastic landing, 44 months after initial retinaculum repair. For revision surgery, we reconstructed the flexor retinaculum in conjunction with deepening of the retromalleolar groove, because the groove was hypoplastic. He returned to competitive gymnastics and had not experienced subluxation or dislocation of the posterior tibial tendon at the 1-year follow-up examination.

MR imaging as a problem solving tool in posterior ankle pain: A review

Posterior ankle pain is a cause of chronic pain and disability, afflicting a wide range of individuals. While proper identification of the cause is essential for timely and adequate treatment, identifying the cause and excluding mimickers is often challenging for the physician due to the complex nature of the joint. In addition, pathology that can cause posterior ankle pain may occur on their own or in co-existence. Clinical conditions that can present as posterior ankle pain include: posterior ankle impingement, Achilles tendon pathology, medial flexor tendon pathology, peroneal pathology, retrocalcaneal bursitis, posterior subtalar tarsal coalition, sinus tarsi, and tarsal tunnel syndrome. In this review we introduce current concepts of pathophysiology in the main conditions involved in posterior ankle pain, and review the role of MR in the diagnosis and management of each condition. When pathology can be detected earlier and with more specificity, appropriate and time-sensitive treatment can be commenced, thus improving clinical outcomes.

Spring ligament complex: Illustrated normal anatomy and spectrum of pathologies on 3T MR imaging

The spring (plantar calcaneonavicular) ligament complex connects the calcaneus and navicular bone of the foot and serves as the primary static stabilizer of the medial longitudinal arch of the foot. In this article, we describe the normal anatomy of the spring ligament complex, illustrate 3T magnetic resonance imaging appearances in its normal and abnormal states, and discuss the pathological associations with relevant case examples.

Comparison of preoperative MRI and intraoperative findings of posterior tibial tendon insufficiency

Background

The purpose of this study was to investigate the radiological and surgical correlation between preoperative magnetic resonance images (MRI) and the intraoperative findings in patients with acquired adult flatfoot.

Results

The overall radiological–surgical correlation between preoperative MRI and the intraoperative findings for posterior tibial tendon insufficiency was only slight to fair in our patient’s series. Comparing the most commonly used posterior tibial tendon classification systems, the classification of Rosenberg et al. and Kong et al. showed higher interobserver agreement than our modified classification system and the classification system of Conti et al.

Conclusion

Further prospective studies are needed to evaluate the importance of preoperative MRI before surgical repair of posterior tibial tendon dysfunction.

Magnetic Resonance Imaging of Sports Injuries Involving the Ankle

Understanding of ankle injuries has evolved for the past few decades, influenced by capability to visualize ligaments, tendons, and bone marrow on magnetic resonance imaging (MRI). Natural history of injury progression, complications, and healing has also been characterized using MRI. Stress injury is particularly common at the ankle in athletes and "weekend warriors" alike. This article will discuss manifestations of ankle injury on MRI as well as associated findings that should be addressed.

Lower limb complications of diabetes mellitus: a comprehensive review with clinicopathological insights from a dedicated high-risk diabetic foot multidisciplinary team

Diabetic complications in the lower extremity are associated with significant morbidity and mortality, and impact heavily upon the public health system. Early and accurate recognition of these abnormalities is crucial, enabling the early initiation of treatments and thus avoiding or minimizing deformity, dysfunction and amputation. Following careful clinical assessment, radiological imaging is central to the diagnostic and follow-up process. We aim to provide a comprehensive review of diabetic lower limb complications designed to assist radiologists and to contribute to better outcomes for these patients.

Posterior Tibialis Tendon Dysfunction: Overview of Evaluation and Management

EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Recognize posterior tibialis tendon dysfunction and begin to include it in differential diagnoses. 2. Recall the basic anatomy and pathology of the posterior tibialis tendon. 3. Assess a patient for posterior tibialis tendon dysfunction with the appropriate investigations and stratify the severity of the condition. 4. Develop and formulate a treatment plan for a patient with posterior tibialis tendon dysfunction. The posterior tibialis is a muscle in the deep posterior compartment of the calf that plays several key roles in the ankle and foot. Posterior tibialis tendon dysfunction is a complex but common and debilitating condition. Degenerative, inflammatory, functional, and traumatic etiologies have all been proposed. Despite being the leading cause of acquired flatfoot, it is often not recognized early enough. Knowledge of the anatomical considerations and etiology of posterior tibialis tendon dysfunction, as well as key concepts in its evaluation and management, will allow health care professionals to develop appropriate intervention strategies to prevent further development of flatfoot deformities.

Posterior tibial tendoscopy

The posterior tibial tendon (PTT) helps the triceps surae to work more efficiently during ambulation. Disorders of the PTT include tenosynovitis, acute rupture, degenerative tears, dislocation, instability, enthesopathies, and chronic tendinopathy with dysfunction and flat foot deformity. Open surgery of the PTT has been the conventional approach to deal with these disorders. However, tendoscopy has become a useful technique to diagnose and treat PTT disorders. This article focuses on PTT tendoscopy and tries to provide an understanding of the pathomechanics of the tendon, indications for surgery, surgical technique, advantages, complications, and limitations of this procedure.

Is advanced imaging necessary before surgical repair

Posterior tibial tendon dysfunction (tendinitis, tendinosis, or rupture) and adult acquired flatfoot deformity can manifest with a wide array of bony and soft tissue abnormalities visible on plain radiographs, ultrasound, and magnetic resonance imaging. Imaging abnormalities include various combinations of malalignment, anatomic variants, and enthesopathic and tendinopathic changes. A thorough understanding of differences between anatomic and pathologic presentations of structures in various imaging modalities is an essential tool for clinical and surgical planning.

Plantar tendons of the foot: MR imaging and US

Tendon disorders along the plantar aspect of the foot may lead to significant symptoms but are often clinically misdiagnosed. Familiarity with the normal anatomy of the plantar tendons and its appearance at magnetic resonance (MR) imaging and ultrasonography (US) is essential for recognizing plantar tendon disorders. At MR imaging, the course of the plantar tendons is optimally visualized with dedicated imaging of the midfoot and forefoot. This imaging should include short-axis images obtained perpendicular to the long axis of the metatarsal shafts, which allows true cross-sectional evaluation of the plantar tendons. Normal plantar tendons appear as low-signal-intensity structures with all MR sequences. At US, accurate evaluation of the tendons requires that the ultrasound beam be perpendicular to the tendon. The normal tendon appears as a compact linear band of echogenic tissue that contains a fine, mixed hypoechoic and hyperechoic internal fibrillar pattern. Tendon injuries can be grouped into six major categories: tendinosis, peritendinosis, tenosynovitis, entrapment, rupture, and instability (subluxation or dislocation) and can be well assessed with both MR imaging and US. The radiologist plays an important role in the diagnosis of plantar tendon disorders, and recognizing their imaging appearances at MR imaging and US is essential.

Magnetic resonance imaging in adolescent symptomatic navicular tuberosity

BACKGROUND

The accessory navicular bone is one of the most common accessory ossicles, which sometimes become symptomatic. Abnormalities in magnetic resonance (MR) image, e. g. edema-like bone marrow pattern, have been reported for symptomatic accessory navicular. However, it has not been completely understood the edema-like bone marrow pattern correlates to the symptom of navicular tuberosity.

METHODS

We investigated the edema-like bone marrow pattern in correlation with alleviation of the symptom and the presence of accessory navicular bone. Ten adolescents with pain localized to the navicular tuberosity were recruited and seven cases were further examined with consecutive MR images.

RESULTS

Edema-like bone marrow pattern was found in all symptomatic navicular but not in asymptomatic navicular. Intensity of the pattern diminished with alleviation of the symptom. Moreover, this correlation was recognized even in the patients who had no accessory navicular bones.

CONCLUSIONS

MR images could be used not only for diagnosis but for monitor of healing in adolescent symptomatic navicular. There may be different pathologic mechanism for adolescent symptomatic navicular tuberosity, such as an osteitis, in adolescents.

Tendon and ligament imaging

MRI and ultrasound are now widely used for the assessment of tendon and ligament abnormalities. Healthy tendons and ligaments contain high levels of collagen with a structured orientation, which gives rise to their characteristic normal imaging appearances as well as causing particular imaging artefacts. Changes to ligaments and tendons as a result of disease and injury can be demonstrated using both ultrasound and MRI. These have been validated against surgical and histological findings. Novel imaging techniques are being developed that may improve the ability of MRI and ultrasound to assess tendon and ligament disease.

3-Tesla magnetic resonance imaging evaluation of posterior tibial tendon dysfunction with relevance to clinical staging

The posterior tibial tendon (PTT) is the most important dynamic stabilizer of the medial ankle and longitudinal arch of the foot. PTT dysfunction is a degenerative disorder of the tendon, which secondarily involves multiple ligaments, joint capsules, fascia, articulations, and bony structures of the ankle, hindfoot, midfoot, and forefoot. When the tendon progressively attenuates, the patient develops a painful, progressive collapsed flatfoot or pes planovalgus deformity. This comprehensive review illustrates the 3-Tesla magnetic resonance imaging (3T MRI) features of PTT dysfunction. In addition, the reader will gain knowledge of the expected pathologic findings on MRI, as they are related to clinical staging of PTT dysfunction.

Os naviculare: the multi-ossicle configuration of a normal variant

OBJECTIVE

To describe the multi-ossicle appearance of the os naviculare on MRI and CT examinations and to correlate this appearance with the published classification of this well-known skeletal variant.

MATERIALS AND METHODS

We retrospectively reviewed 148 patients, examined within a 2-year period (170 CT and MRI studies of the foot-ankle), for the presence of os naviculare. This variant was classified according to a widely used system (type I, II, III). In addition, each navicular variant was further reclassified according to the presence of one or more ossicles. The presence of bone marrow edema was also recorded.

RESULTS

Accessory navicular bone was identified in 34 cases (20%) of the 170 exams. It was detected in 14 male and 14 female patients with the following incidence: 11.15% type I (19 cases), 4.11% type II (7 cases) and 4.74% type III (8 cases). In six cases the location was bilateral. Among patients with os naviculare, a multi-ossicle appearance with a total incidence of 14.7% (8.8% two ossicle configuration and 5.9% three ossicle configuration) was observed. In two type II cases studied with MRI, there was bone marrow edema suggesting a painful pseudarthrosis.

CONCLUSION

The presence of multiple accessory navicular bone ossicles, not previously described with cross-sectional imaging, is reported herein. The pathogenesis and clinical relevance of this uncommon variant needs to be elucidated with further studies.

''Reappearance'' of a transferred flexor digitorum longus tendon fixed with a bioresorbable interference screw on postoperative MRI: case report

Level of Evidence: V, Expert Opinion

Dislocation of the tibialis posterior tendon treated with autogenous bone block: a case report

Level of Evidence: V, Expert Opinion

Chiasma crurale: intersection of the tibialis posterior and flexor digitorum longus tendons above the ankle. Magnetic resonance imaging-anatomic correlation in cadavers

PURPOSE

To determine the precise anatomy and magnetic resonance (MR) imaging appearance of the chiasma crurale in cadavers, paying special attention to degenerative changes

MATERIAL AND METHODS

Twelve fresh human ankles were harvested from 11 nonembalmed cadavers (mean age at death 77 years) and used according to institutional guidelines. MR imaging and MR tenography were used to investigate the anatomy of the chiasma crurale using proton density-weighted sequences. The gross anatomy of the chiasma crurale was evaluated and compared to the MR imaging findings. Histology was used to elucidate further the structure of the chiasma crurale.

RESULTS

Above the chiasma, five specimens had a small amount of fat tissue between the tibialis posterior and flexor digitorum longus tendon. In all specimens both tendons had a sheath below the chiasma but not above it. At the central portion of the chiasma there was no soft tissue between the tendons, except in two specimens that showed an anatomic variant consisting of a thick septum connecting the tibial periosteum and the deep transverse fascia of the leg. In MR images, eight specimens showed what were believed to be degenerative changes in the tendons at the level of the chiasma. However, during gross inspection and histologic analysis of the specimens, there was no tendon degeneration visible.

CONCLUSION

At the central portion of the chiasma, there is no tissue between the tibialis posterior and flexor digitorum longus tendons unless there is an anatomic variant. At the chiasma crurale, areas with irregular tendon surfaces are normal findings and are not associated with tendon degeneration (fraying).