Magic angle effect in MR imaging of ankle tendons: influence of foot positioning on prevalence and site in asymptomatic subjects and cadaveric tendons

The influence of foot positioning on prevalence of the magic angle effect (MAE) in ankle tendons was investigated. In 30 asymptomatic volunteers and five cadaveric feet, MR imaging of the ankle was performed in the supine (neutral position of the foot) and prone (plantar-flexed foot) position. MAE was considered if increased T1-weighted signal at a certain site was seen in one position only. Histological correlation was obtained at 25 sites of the cadaveric posterior tibialis tendons (PTT). MAE occurred in 6/30 vs 1/30 (supine vs prone) anterior tibialis tendons (ATT), 30/30 vs 0/30 extensor hallucis longus and 27/30 vs 0/30 extensor digitorum longus tendons, 29/30 vs 0/30 PTTs, 30/30 vs 0/30 flexor digitorum and flexor hallucis longus tendons, 30/30 vs 1/30 peroneus brevis and 23/30 vs 1/30 peroneus longus tendons. At 12/25 cadaveric PTT sites where MAE was exclusively responsible for the increased signal, histology revealed normal tissue (11/12) or minimal degeneration (1/12). In conclusion, the supine body position with neutral position of the foot, a high prevalence (77–100%) of MAE in ankle tendons except for the ATT (20%) is seen. MAE is almost absent in the prone body position with plantar flexion of the foot.     

Tendons in the plantar aspect of the foot: MR imaging and anatomic correlation in cadavers

Objective: The purpose of this anatomic imaging study was to illustrate the normal complex anatomy of tendons of the plantar aspect of the ankle and foot using magnetic resonance (MR) imaging with anatomic correlation in cadavers. Design: Seven fresh cadaveric feet (obtained and used according to institutional guidelines, with informed consent from relatives of the deceased) were studied with intermediate-weighted fast-spin-echo MR imaging. For anatomic analysis, cadaveric specimens were sectioned in 3-mm-thick slices in the coronal and axial planes that approximated the sections acquired at MR imaging. Results: The entire courses of the tendons into the plantar aspect of the foot were analyzed. The tibialis posterior tendon has a complex distal insertion. The insertions in the navicular, second, and third cuneiforms bones were identify in all cases using axial and coronal planes. A tendinous connection between the flexor hallucis longus and the flexor digitorum longus tendons was identified in five of our specimens (71%). The coronal plane provided the best evaluation. The peroneus longus tendon changes its direction at three points then obliquely crosses the sole and inserts in the base of the first metatarsal bone and the plantar aspect of the first cuneiform. Conclusions: MR imaging provides detailed information about the anatomy of tendons in the plantar aspect of the ankle and foot. It allows analysis of their insertions and the intertendinous connection between the flexor hallucis longus and the flexor digitorum longus tendons.     

“Intersection syndrome” of the foot: treated by endoscopic release of master knot of Henry

Intersection syndrome of the forearm is a painful condition in the area where the muscle bellies of the abductor pollicis longus and extensor pollicis brevis cross the common wrist extensors. A similar case of the foot with marked fibrosis at the interconnection of flexor hallucis longus and flexor digitorum tendons is reported and the fibrous interconnection was extended proximally. This was successfully treated with endoscopic release of the master knot of Henry.     

Initial experience with visualizing hand and foot tendons by dual-energy computed tomography

PurposeTo assess the feasibility of visualizing hand and foot tendons by dual-energy computed tomography (CT).Methods and materialsTwenty patients who suffered from hand or feet pains were scanned on dual-source CT (Definition, Forchheim, Germany) with dual-energy mode at tube voltages of 140 and 80 kV and a corresponding ratio of 1:4 between tube currents. The reconstructed images were postprocessed by volume rendering techniques (VRT) and multiplanar reconstruction (MPR). All of the suspected lesions were confirmed by surgery or follow-up studies.ResultsTwelve patients (total of 24 hands and feet, respectively) were found to be normal and the other eight patients (total of nine hands and feet, respectively) were found abnormal. Dual-energy techniques are very useful in visualizing tendons of the hands and feet, such as flexor pollicis longus tendon, flexor digitorum superficialis/profundus tendon, Achilles tendon, extensor hallucis longus tendon, and extensor digitorum longus tendon, etc. It can depict the whole shape of the tendons and their fixation points clearly. Peroneus longus tendon in the sole of the foot was not displayed very well. The distal ends of metacarpophalangeal joints with extensor digitoium tendon and extensor pollicis longus tendon were poorly shown. The lesions of tendons such as the circuitry, thickening, and adherence were also shown clearly.ConclusionDual-energy CT offers a new method to visualize tendons of the hand and foot. It could clearly display both anatomical structures and pathologic changes of hand and foot tendons.     

职业足球运动员足踝关节无症状慢性损伤MR影像特点的初步研究

目的分析职业足球运动员足踝关节无症状慢性损伤的MR影像特点。方法募集2017年3月—5月间18名天津当地足球俱乐部的现役运动员作为研究对象,均可正常参加训练和比赛,且至本次检查6个月内均无足踝关节不适症状。采用3.0 T MRI进行踝关节扫描,观察每位运动员踝关节的骨质、韧带、肌腱情况。采用Fisher精确检验比较触球足和立足足踝关节不同结构损伤情况的发生率。结果骨质损伤主要表现为骨髓水肿、囊变、关节游离体形成及不规则骨突形成。其中骨髓水肿共12例17个踝关节(触球足10个,立足7个);3例3个踝关节(触球足1个,立足2个)可见关节游离体形成;7例7个踝关节(触球足5个,立足2个)出现距后三角骨。2例2个踝关节(触球足、立足各1个)可见距骨后突。触球足组和立足组间骨质损伤发生率差异均无统计学意义(均P0.05)。内侧三角韧带损伤5例共5个踝关节(触球足2个,立足3个);距腓前韧带损伤17例共25个踝关节(触球足8个,立足17个);跟腓韧带损伤9例12个踝关节(触球足5个,立足7个);下胫腓前韧带损伤1例1个踝关节(触球足);未见距腓后韧带、下胫腓后韧带损伤病例。立足组距腓前韧带损伤发生率高于触球足组(P=0.003)。其余韧带损伤发生率,2组间差异无统计学意义(均P0.05)。肌腱损伤主要表现为腱鞘积液,踇长屈肌腱腱鞘积液17例26个踝关节(触球足12个,立足14个);趾长屈肌腱腱鞘积液8例10个踝关节(触球足5个,立足5个);胫骨后肌腱腱鞘积液9例12个踝关节(触球足5个,立足7个);腓骨长短肌腱腱鞘积液4例4个踝关节(触球足2个,立足2个);趾长伸肌腱腱鞘积液2例2个踝关节(触球足1个,立足1个)。未发现胫骨前肌腱、踇长伸肌腱腱鞘积液及跟腱周围积液。触球足组和立足组间腱鞘积液发生率差异均无统计学意义(均P0.05)。结论职业足球运动员艰苦的训练和比赛容易造成踝关节反复创伤,主要特点为骨髓水肿、囊变,韧带损伤及腱鞘积液。由于双足在足球运动中功能不同,触球足和立足损伤特点亦不同。     

Skimboarder's toe: findings on high-field MRI

OBJECTIVE: Our purpose is to report hyperdorsiflexion injuries of the metatarsophalangeal joints associated with the sport of skimboarding and to describe the MRI appearance of these injuries. CONCLUSION: Skimboarding can be associated with hyperdorsiflexion injuries of the metatarsophalangeal joint. MRI shows that such injuries are associated with hyperdorsiflexion of the extensor hallucis longus or extensor digitorum longus tendon, causing tear of the extensor expansion. Unlike turf toe, in which the plantar plate is involved, skimboarder's toe involves structures dorsal to the metatarsophalangeal joint.     

MR imaging of the tarsal tunnel and related spaces: normal and abnormal findings with anatomic correlation

The tarsal tunnel syndrome may be caused by extrinsic or intrinsic pressure on the posterior tibial nerve or its terminal branches. The specific symptoms depend on the extent of nerve involvement, and compression distal or proximal to the tarsal tunnel may result in variants of the syndrome. To define better the capability of MR imaging for evaluating this entity, we performed MR imaging on three normal subjects and correlated the images with cryomicrotome sections. Six patients with symptoms suggestive of tarsal tunnel syndrome also were studied with MR. In all normal subjects, MR images showed the flexor retinaculum and the structures passing deep to the retinaculum: the tibialis posterior tendon, flexor digitorum longus tendon, flexor hallucis longus tendon, and the posterior tibial neurovascular bundle. The medial calcaneal sensory branch(es) and the medial and lateral plantar nerves also were delineated. Mechanical causes of compression were shown in all six symptomatic patients. The pathologic entities included two neurilemomas, tenosynovitis involving all three tendons, a ganglion cyst arising from the flexor hallucis longus tendon sheath, posttraumatic fibrosis, and post-traumatic fibrosis with associated posttraumatic neuroma. The MR findings were confirmed surgically in five cases. MR imaging can accurately depict the contents of the tarsal tunnel and the courses of the terminal branches of the posterior tibial nerve. In our small series, MR imaging accurately showed the lesions responsible for tarsal tunnel syndrome.     

Correlation of morphologic and pathologic features of the various tendon groups around the ankle: MR imaging investigation

Objective

To determine if a statistical association exists between abnormalities in one ankle tendon group (i.e., peroneal, medial flexor, or Achilles) and those in another.

Materials and methods

A retrospective analysis of 1.5-T and 3-T MR ankle examinations in 100 patients conducted between November 1, 2011 and April 1, 2012 was performed. The cross-sectional areas and diameters of the ankle tendons—Achilles (ACH), peroneus brevis (PB) and longus (PL), tibialis posterior (TP), flexor digitorum longus (FDL), and flexor hallux longus (FHL)—were measured, and the results were correlated to determine any association with the presence of qualitative abnormalities (tenosynovitis, tendinosis, and tendon tearing).

Results

Subjects with larger diameters of the ACH tendon also revealed larger PL, TP, FDL, and FHL tendon diameters and sectional areas. Furthermore, subjects with larger PL tendons generally revealed larger flexor tendons and the same was also true when medial compartment tendons were individually assessed and measurements compared among the three of them. There was a statistically significant association with regard to the presence of tendon abnormalities (tendinosis, tenosynovitis, and tearing) in both the peroneal and medial flexor tendons. The presence of an abnormality in the ACH tendon correlated strongly with increasing diameters and areas of all the other ankle tendons except for the PB tendon.

Conclusions

There is an association between quantitative and qualitative abnormalities of one group of tendons when compared with the others with respect to the ACH, medial flexor, and peroneal tendons of the ankle, which is perhaps explained by a retinacular and fascial complex that anatomically connects the three groups.     

The dorsal pedis artery as a new distal landmark for extramedullary tibial alignment in total knee arthroplasty

Purpose

It is better to use multiple anatomical landmarks to reduce errors in component alignment in total knee arthroplasty. Therefore, it is worthwhile to find a new landmark that can be used as an addition to conventional ones. Herein, we assessed the dorsal pedis artery as a new distal landmark for extramedullary tibial alignment.

Methods

Fifty-two ankles in patients undergoing total knee arthroplasty and 10 ankles in normal controls were included. Color Doppler ultrasonography was used to locate the dorsal pedis artery at the level of the ankle joint. Conventional landmarks, including the tibialis anterior tendon, the extensor hallucis longus tendon, the extensor digitorum longus tendon, and the malleolar centre, were also located on ultrasound images. The distances between the ankle centre and each landmark were measured and compared.

Results

The dorsal pedis artery was absent in 2 patients and impalpable but visible with ultrasonography in other 2 patients. The dorsal pedis artery was located anatomically closest to the ankle centre in patients (0.4 ± 3.4 mm lateral). Statistical analysis showed that the dorsal pedis artery, the extensor hallucis longus tendon, and the malleolar centre were located significantly closer to the ankle centre comparing with the extensor digitorum longus tendon and the tibialis anterior tendon in both patients and controls (p < 0.001).

Conclusions

As long as the dorsal pedis artery exists, it can be used as an addition to the conventional landmarks in total knee arthroplasty. Using this new landmark will help reduce errors in coronal plane alignment of tibial component.

Level of evidence

II.     

Extrinsic foot muscle forces and joint contact forces in flexible flatfoot adult with foot orthosis: A parametric study of tibialis posterior muscle weakness

BackgroundThe posterior tibialis tendon dysfunction (PTTD) is typically associated with progressive flatfoot deformity, which could be alleviated with foot orthosis. However, the evaluation of tibialis posterior (TP) weakness on lower limb mechanics of flatfoot adults with foot orthoses is scarce and requires further investigation.Research questionThis study aimed to examine the effects of TP weakness on lower limb mechanics in flatfoot adults with foot orthosis through gait analysis and musculoskeletal modelling.MethodsFifteen young adults with flatfoot were recruited from University to perform a gait experiment with and without foot orthoses. Data collected from the motion capture system were used to drive the musculoskeletal modelling for the estimation of the joint force and extrinsic muscle forces of the lower limb. A parametric analysis was conducted by adjusting the TP muscle strength from 40 % to 100 %. Two-way repeated measures ANOVA was used to compare the peak extrinsic foot muscle forces and joint forces among different levels of TP weakness and insole conditions.ResultsTP weakness significantly increased ankle joint force superoinferiorly (F = 125.9, p < 0.001) and decreased anteroposteriorly (F = 125.9, p < 0.001), in addition to a significant increase in the muscle forces of flexor hallucis longus (p < 0.001) and flexor digitorum longus (p < 0.001). Besides, the foot orthosis significantly reduced most peak muscle forces whilst significantly reduced the second peak knee force and peak ankle force compared to the control condition (F = 8.79–30.9, p < 0.05).SignificanceThe increased extrinsic foot muscle forces (flexor hallucis longus and flexor digitorum longus) and ankle joint forces in the TP weakness condition indicated that TP weakness may induce compensatory muscle activation and attenuated joint load. The abnormal muscle and joint mechanics in flatfoot adults with TP weakness might be restored by the orthosis.     

Bilateral aplasia of the tibialis anterior and unilateral aplasia of the extensor hallucis longus muscles

A 35-year-old woman presented with bilateral leg pain on walking that had been present since childhood. Clinical examination showed bilateral absence of the tibialis anterior tendons and the left extensor hallucis longus tendon. Magnetic resonance imaging revealed that signal intensities in the location of the tibialis anterior muscles bilaterally and the left extensor hallucis longus muscle were uniformly high on T1-weighted images, consistent with fat tissue and aplastic muscles: findings not previously reported.     

Relationship between foot muscle morphology and severity of pronated foot deformity and foot kinematics during gait: A preliminary study

BackgroundThe morphology of foot muscles that support the medial longitudinal arch differs between normal and pronated feet. The degree to which the difference depends on the severity of the pronated foot deformity is unclear. In the clinical setting, however, to reduce the pronated deformity, muscle-strengthening exercises are performed.Research questionDoes a relationship exist between foot muscle morphology and severity of the pronated foot deformity and foot kinematics during gait?MethodsUsing the six-item foot posture index (FPI-6), 26 study participants were assessed for their foot posture and divided into two groups of 13 participants each based on the FPI-6 score: pronated foot group (with a score of 6–9) and highly pronated foot group (with a score of 10–12). Select foot muscles were scanned with ultrasonography, and muscle thicknesses were measured. The following were the muscles of interest: abductor hallucis, flexor hallucis brevis and longus, flexor digitorum brevis and longus, and peroneus longus. Foot kinematic data during gait was collected using a three-dimensional motion capture system as a dynamic navicular drop.ResultsNo between-group differences were noted for muscle thickness and dynamic navicular drop. However, the abductor hallucis and flexor hallucis brevis thicknesses were correlated with the dynamic navicular drop, but not with the severity of the pronated foot deformity.SignificanceIn individuals with pronated foot deformity, more developed abductor hallucis and flexor hallucis brevis muscles may reduce the dynamic navicular drop that represents the degree of medial longitudinal arch deformation during the stance phase of gait.     

Ultrasound evaluation of foot muscles and plantar fascia in pes planus

BackgroundMultiple intrinsic and extrinsic soft tissue structures that apply forces and support the medial longitudinal arch have been implicated in pes planus. These structures have common functions but their interaction in pes planus is not fully understood. The aim of this study was to compare the cross-sectional area (CSA) and thickness of the intrinsic and extrinsic foot muscles and plantar fascia thickness between normal and pes planus feet.MethodsForty-nine adults with a normal foot posture and 49 individuals with pes planus feet were recruited from a university population. Images of the flexor digitorum longus (FDL), flexor hallucis longus (FHL), peroneus longus and brevis (PER), flexor hallucis brevis (FHB), flexor digitorum brevis (FDB) and abductor hallucis (AbH) muscles and the plantar fascia were obtained using a Venue 40 ultrasound system with a 5–13 MHz transducer.ResultsThe CSA and thickness of AbH, FHB and PER muscles were significantly smaller (AbH −12.8% and −6.8%, FHB −8.9% and −7.6%, PER −14.7% and −10%), whilst FDL (28.3% and 15.2%) and FHL (24% and 9.8%) were significantly larger in the pes planus group. The middle (−10.6%) and anterior (−21.7%) portions of the plantar fascia were thinner in pes planus group.ConclusionGreater CSA and thickness of the extrinsic muscles might reflect compensatory activity to support the MLA if the intrinsic foot muscle function has been compromised by altered foot structure. A thinner plantar fascia suggests reduced load bearing, and regional variations in structure and function in feet with pes planus.     

MR imaging in tarsal tunnel syndrome.

Magnetic resonance imaging was used to demonstrate the normal anatomy of the tarsal tunnel in two volunteers and to evaluate 33 feet in 27 patients with tarsal tunnel syndrome. The tarsal tunnel is a fibroosseous channel extending from the ankle to the midfoot, through which the medial tendons and the posterior tibial neurovascular bundle pass. Tarsal tunnel syndrome is a compression neuropathy of the posterior tibial nerve or one of its branches and may be caused by a variety of pathologic lesions. Magnetic resonance imaging demonstrated a mass lesion in five feet, dilated veins or varicosities in eight feet, fracture or soft tissue injury in five feet, fibrous scar in two feet, flexor hallucis longus tenosynovitis in six feet, and abductor hallucis muscle hypertrophy in one foot. Six feet were normal on MR imaging. The findings of MR imaging were confirmed in 17 of 19 patients that went to surgery. Magnetic resonance is useful for localizing lesions within the tarsal tunnel and for determining the lesion extent and relationship to the posterior tibial nerve and its branches.     

Intermittent dislocation of the flexor hallucis longus tendon

Dislocation of the flexor hallucis longus tendon is an exceptional occurrence. To our knowledge, this is the first case ever reported of an intermittent dislocation in a 17-year-old woman; she was a synchronised swimmer. She consulted for a right internal retro-malleolar syndrome. Voluntary "snap" was triggered by a mechanism which combined maximal ankle dorsiflexion and interphalangeal plantar flexion of the toes. Non-enhanced dynamic helical CT and axial MRI were performed, which revealed the dislocation of the right flexor hallucis longus tendon outside the posterior intertubercular talar groove. Static and dynamic imaging would appear to be required to make this uncommon diagnosis.     

Management of posterior tibial tendinitis in the athlete

Posterior tibial tendinitis in the young patient is relatively uncommon. However, when it occurs, it can be debilitatingand considerably limit athletic function. Aggressive nonoperative treatment is indicated initially. If this fails, tenosynovectomy can restore function and relieve pain. If the degree of tendon degeneration is extensive, primary repair and/or augmentation with flexor digitorum longus or flexor hallucis longus transfer will be necessary. While short term results are encouraging in patients overall, little is known about the long-term prognosis or the results in young, high-demand individuals.     

Closed ruptures of the flexor digitorum tendons: MRI evaluation

Objective. To assess the MRI findings in cases of closed rupture of the flexor digitorum tendons (FDT). Patients and design. Ten patients with a clinical suspicion of rupture of FDT underwent MRI before surgery. None of the patients presented a skin injury. Fingers were imaged using axial T1-weighted SE sequences, three-dimensional GE images, and curved reconstructions. Results. Twelve FDT had surgical confirmation of rupture. Flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) tendons were more frequently ruptured (n=8) than flexor digitorum superficialis (FDS) tendons (n=4). MR images accurately depicted the level of the rupture. The gap between the tendon ends (mean 45 mm, range 21–70 mm) was assessed best with curved reconstructions and was well correlated with the surgical findings. The proximal end mainly retracted into the palm or the carpal tunnel (n=8), and less frequently into the digital canal (n=4). In two cases, the proximal end curled up in the palm, clinically simulating a rupture of a lumbrical muscle in one case. MRI also showed the appearance of the adjacent tendons. Conclusion. MRI accurately depicted the level of rupture and the gap between the tendon ends, which assisted the surgical choice between suture, graft or tendon transfer.     

Tendon injuries of the foot and ankle.

Tendon injuries are often caused by direct trauma or overuse. Pathology may consist of inflammatory lesions external to the tendon sheath or inflammation of either the peritenon, sheath, or tendon. This article reviews the diagnosis and treatment of injuries to the peroneal, peroneus brevis, peroneus longus, anterior tibial, flexor hallucis longus, and posterior tibial tendons.     

Diagnostic and therapeutic ankle tenography: outcomes and complications

OBJECTIVE: The purpose of our study was to evaluate tenography complications and outcomes in a large series. MATERIALS AND METHODS: Of 144 tenograms obtained consecutively from May 5, 1995, to March 17, 1997, 111 were located for at least a 6-month follow-up; 65 were posterior tibial, 39 peroneal, two anterior tibial, three flexor digitorum longus, and two flexor hallucis longus tenograms. Tenography was performed fluoroscopically with contrast material and anesthetic followed by steroid placement into tendon sheaths. RESULTS: Of 65 patients undergoing posterior tibial tenography, 31 (48%) had complete or near-complete symptom resolution; 17 (26%) had no relief. Seventeen patients (26%) had initial relief with the subsequent return of pain to the pretenography level. Of 39 patients undergoing peroneal tenography, 18 (46%) had complete or near-complete symptom resolution; 10 (26%) had no and 11 (28%) had initial relief with subsequent pretenography pain return. Of three patients undergoing flexor digitorum longus tenography, one had complete, one had no, and one had initial relief with complete pretenography pain return. One of two patients who underwent flexor hallucis longus tenography had no relief; the other had initial relief with complete pain return. Two patients who underwent anterior tibial tenography had complete pain relief. We found no correlation between degree of tenosynovitis shown radiographically and therapeutic improvement with anesthetic and steroid injection. Tenography complications included one posterior tibial tendon rupture (0.89%) and 14 patients with skin discoloration at the tendon sheath injection site. CONCLUSION: Forty-seven percent of surgical candidates whose condition was refractory to conservative therapy had complete or near-complete prolonged symptom relief after tenography. In appropriate patients, tenography is excellent therapy for tenosynovitis. Certain precautions make complications rare.     

Chondroma within the flexor hallucis longus tendon sheath. A case report and literature review

Chondromas in tendon sheaths are a rare entity proviously reported in the flexor sheaths on the hand and possibly the foot. This is the first reported case of condroma of the flexor hallucis longus tendon sheath at the ankle region. A literature review with regard to pathogenesis, classification, and recurrence has been presented.