Plantar compartments of the foot: MR appearance in cadavers and diabetic patients

Chronic Exertional Compartment Syndrome of the Foot

Active individuals can experience exercise-induced pain along the medial, plantar central, and plantarmedial proximal arch. In many cases, these symptoms are consistent with conditions involving the plantar fascia, posterior tibial tendon, or entrapment of branches of the posterior tibial nerve. Unlike these other conditions, chronic exertional compartment syndrome (CECS) of the foot can be aggravated by interventions that impart any pressure or compression to the foot. Practitioners should have a high index of suspicion for CECS when classic treatments tend to aggravate patient's symptoms.

Anatomy of foot Compartments: a systematic review

INTRODUCTION

There are discrepancies regarding the anatomy of the foot which complicate standardizing foot compartment treatment. We synthesized the existing evidence regarding the compartmental anatomy of the foot MATERIALS AND METHODS: A systematic review was performed evaluating the anatomy of the foot compartments in non-pathologic specimens. The search strategy was performed in MEDLINE, Scopus, Web of Science, and EMBASE. Three reviewers worked independently and in duplicate to screen all references via a title/abstract and full-text phase. The risk of bias was assessed with the Anatomical Quality Assurance (AQUA) checklist.

RESULTS

Ten studies were included. All were performed in cadavers except one. Half of them evaluated the plantar section of the foot and the other half evaluated the whole foot. Methods employed across studies tended to vary: anatomical dissections, dye infusion, imaging studies, or a combination of these. Five studies directly addressed the anatomic limits of each compartment and eight addressed the anatomical structures inside each of them. There seems to be an agreement regarding the number of compartments in the plantar region (three major compartments divided by the medial and lateral intermuscular septum), nevertheless, disagreements across authors tend to arise when describing its dorsal section. Only two studies were ranked with an overall low risk of bias, agreeing on nine compartments.

CONCLUSION

This review provides the best available anatomical evidence regarding the anatomy of the foot compartments for compartment syndrome management. Future research should focus on settling the discrepancies highlighted to reach a more accurate anatomical description.

Imaging of plantar fascia disorders: findings on plain radiography, ultrasound and magnetic resonance imaging

Plantar fascia (PF) disorders commonly cause heel pain and disability in the general population. Imaging is often required to confirm diagnosis. This review article aims to provide simple and systematic guidelines for imaging assessment of PF disease, focussing on key findings detectable on plain radiography, ultrasound and magnetic resonance imaging (MRI). Sonographic characteristics of plantar fasciitis include PF thickening, loss of fibrillar structure, perifascial collections, calcifications and hyperaemia on Doppler imaging. Thickening and signal changes in the PF as well as oedema of adjacent soft tissues and bone marrow can be assessed on MRI. Radiographic findings of plantar fasciitis include PF thickening, cortical irregularities and abnormalities in the fat pad located deep below the PF. Plantar fibromatosis appears as well-demarcated, nodular thickenings that are iso-hypoechoic on ultrasound and show low-signal intensity on MRI. PF tears present with partial or complete fibre interruption on both ultrasound and MRI. Imaging description of further PF disorders, including xanthoma, diabetic fascial disease, foreign-body reactions and plantar infections, is detailed in the main text. Ultrasound and MRI should be considered as first- and second-line modalities for assessment of PF disorders, respectively. Indirect findings of PF disease can be ruled out on plain radiography.

Teaching Points

• PF disorders commonly cause heel pain and disability in the general population.

• Imaging is often required to confirm diagnosis or reveal concomitant injuries.

• Ultrasound and MRI respectively represent the first- and second-line modalities for diagnosis.

• Indirect findings of PF disease can be ruled out on plain radiography.

Benign and malignant tumors of the foot and ankle

Pain and focal masses in the foot and ankle are frequently encountered and often initiate a workup including imaging. It is important to differentiate benign lesions from aggressive benign or malignant lesions. In this review, multiple examples of osseous and soft tissue tumors of the foot and ankle will be presented. Additionally, the compartmental anatomy of the foot and ankle will be discussed in terms of its relevance for percutaneous biopsy planning and eventual surgery. Finally, a general overview of the surgical management of benign, benign aggressive and malignant tumors of the foot and ankle will be discussed.

Compartments of the foot: topographic anatomy

Recent publications have renewed the debate regarding the number of foot compartments. There is also no consensus regarding allocation of individual muscles and communication between compartments. The current study examines the anatomic topography of the foot compartments anew using 32 injections of epoxy-resin and subsequent sheet plastination in 12 cadaveric foot specimens. Six compartments were identified: dorsal, medial, lateral, superficial central, deep forefoot, and deep hindfoot compartments. Communication was evident between the deep hindfoot compartment and the superficial central and deep central forefoot compartments. In the hindfoot, the neurovascular bundles were located in separate tissue sheaths between the central hindfoot compartment and the medial compartment. In the forefoot, the medial and lateral bundles entered the deep central forefoot compartment. The deep central hindfoot compartment housed the quadratus plantae muscle, and after calcaneus fracture could develop an isolated compartment syndrome.

Extended leg infection of diabetic foot ulcers: risk factors and outcome

OBJECTIVE

To identify the risk factors for extension of infection to the leg in diabetic foot ulcers (DFU) and to evaluate its role as a prognostic measure regarding limb salvage and healing time.

METHOD

This retrospective case-control study took place in Jabir Abu Eliz Diabetic (JADC) during 2006-2008. Forty-eight patients diagnosed with a diabetic foot ulcer (DFU) with the infection extending to the leg (case group) were compared with an equal number of patients with a DFU without extension (control group). Risk factors for extension were identified by univariate analysis and both groups were compared with regard to limb salvage and healing time.

RESULTS

Previous history of toe amputation was more frequent in the case group (p=0.004). The case group patients were significantly more likely to present with fever (p=0.01), pallor (p=0.02), confusion (p=0.04), and necrosis (p=0.004). Ulcers located in the heel were more frequent in the case group when compared with controls (p=0.0001) while more toes ulcers were found in the control group (p=0.001). A significant number of patients in the case group had an ulcer of more than 5cm diameter compared with those in the control group (p=0.001). The total number of patients presented with severe disease (Wagner grade 3-5) was significantly more in the case group compared with controls (p=0.004). Patients with severe infection (grade 4) were more in the case group compared with the controls (p=0.04). There were no significant differences between the two groups with regard to major and minor amputation rate. The case group had a longer duration of healing when compared with the controls. Seventy-five per cent of the controls healed by 6 months (n=31) compared with 22% in the case group (n=8 ; p=0.001).

CONCLUSION

Toe amputation, wound located in the heel, wound size more than 5cm and advanced Wagner grade (3-5) and severe sepsis, grade 4, may be considered as risk factors for extension of infection to the leg in DFU. However, this extension did not carry a poor prognostic value to the final outcome if adequate therapeutic measures were followed.

[Principles of treatment for deep infections of the diabetic foot]

Infections are the typical complications of ulcers related to the neuropathic diabetic foot. The loss of the foot or sepsis is the consequence due to the progression of an untreated infection. Therefore, prophylaxis of ulcer formation is the key to lower the rate of amputation. If infection has occurred antibiotics and non-weight bearing are indicated. Abscesses and phlegmons can be localized by the clinical findings, ultrasound, x-rays, computer tomography and MRI and immediate surgical treatment is necessary to prevent further spreading. In the chronic phase dead tissue, necrotic tendons and bones need to be resected. Closure of the skin can be achieved by secondary healing or other methods of plastic surgery. Persistent bony prominences have to be removed and instabilities need fusion operations. In this way many amputations can be avoided or the extent of amputation can be noticeably reduced.

Modeling of the spread of infection in the interdigital spaces of the manus in limbs from clinically normal dogs

OBJECTIVE

To determine whether the pattern of extension of modeled infection from the interdigital web spaces in dogs is predictable and whether the distribution differs among initial injury sites.

SAMPLE POPULATION

Thawed frozen forelimbs from 23 cadavers of previously healthy adult medium- to large-breed dogs.

PROCEDURES

The manus of each forelimb was evaluated by use of computed tomography (CT) before and after injection of radiopaque blue-staining contrast medium into the interdigital web spaces. Two veterinary radiologists reviewed the CT images and recorded the extent of contrast medium from each site. Each manus was dissected or sectioned transversely after imaging, and the extent of contrast medium accumulation was recorded and compared with locations of CT contrast enhancement. The Fisher exact test was performed to determine whether the pattern of contrast medium extension differed by injection site.

RESULTS

Injections made in the interdigital web spaces of the canine manus led to unique and predictable patterns of extension into the surrounding soft tissues. That pattern of extension primarily involved the soft tissues of the digits.

CONCLUSIONS AND CLINICAL RELEVANCE

In humans, knowledge of common extension patterns from infected soft tissue spaces is used to predict the spread of disease within the hand and develop surgical plans that will minimize patient illness. Identification of the common sites of disease spread from the interdigital web spaces in dogs may help improve surgical planning and treatment for infection in the manus.

Compartment syndrome and lower-limb fasciotomies in the combat environment

Prophylactic and therapeutic treatment of leg compartment syndrome with decompression by double-incision fasciotomy prevents progression of soft-tissue injury in high-energy trauma. This treatment is the standard of care in civilian trauma and combat settings. More controversial is the use of either single- or dual-incision fasciotomy of the foot for prophylactic treatment of foot compartment syndrome. Fasciotomy must be performed in the face of major trauma to the foot with severe swelling and unremitting pain. The role for prophylactic fasciotomy of the foot is unclear and should be considered on a case by case basis. The surgeon must maintain a high degree of vigilance for the development of compartment syndrome in the combat casualty.

Current concepts in imaging diabetic pedal osteomyelitis

Diabetic pedal osteomyelitis is primarily a manifestation of vascular insufficiency with resultant tissue ischemia, neuropathy, and infection. Nearly all cases of pedal osteomyelitis arise from a contiguous ulcer and soft tissue infection. MR imaging is the modality of choice to assess for the presence of osteomyelitis and associated soft tissue complications, to guide patient management, and to aid in limited limb resection.

The compartments of the foot: a 3-tesla magnetic resonance imaging study with clinical correlates for needle pressure testing

BACKGROUND

Reliable measurement of subfascial pressures represents an essential part of compartment syndrome management. To date, there is neither consensus on the number or location of foot compartments, nor a standardized protocol for needle placement. The purpose of this study was to devise a new system using 3-Tesla MRI that assesses the number and location of these compartments.

METHODS

To document the specific location of foot compartments, high resolution 3-Tesla MRI (General Electric, Milwaukee, WI) was coupled with a dedicated transmit-receive high signal-to-noise foot/ankle coil (IGC-Medical Advances, Milwaukee, WI). Individual compartments were highlighted and mapped to T1-weighted MRI. Three-dimensional image analysis allowed standardized needle placement recommendations.

RESULTS

Six feet from healthy volunteers were imaged. From these, ten compartments were described: (1) medial, (2) central superficial, (3) central deep (adductor), (4) lateral, (5-8) interossei, (9) calcaneal, and (10) skin. Optimal needle placement and depth were identified.

CONCLUSIONS

The proposed system allowed us to assess the number and location of foot compartments. Computer image analysis enabled us to define exact points for needle insertion and depth of penetration for accurate pressure monitoring.

Anatomic compartments of the foot: a 3-Tesla magnetic resonance imaging study

There is neither consensus on the number nor agreement on the location of the anatomic compartments of the foot. This project utilized high-resolution magnetic resonance imaging (MRI) to identify foot compartments. The purpose of this study was to devise a new system using 3-Tesla (3T) MRI that assessed the number and location of these compartments. Six feet from healthy volunteers were imaged. From these, 10 compartments were described: (1) medial, (2) calcaneal, (3) lateral, (4) central superficial, (5) central deep (adductor), (6-9) interossei, and (10) skin. The 3T MRI and foot/ankle coil allowed us to assess the number and location of foot compartments.

Neuropathic arthropathy of the foot with and without superimposed osteomyelitis: MR imaging characteristics

PURPOSE

To determine retrospectively the magnetic resonance (MR) findings associated with pedal neuropathic arthropathy with and without superimposed osteomyelitis and to identify any useful discriminating features.

MATERIALS AND METHODS

Investigational review board approval was obtained and allowed review of records and images without informed consent. HIPAA compliance was observed. Contrast-enhanced MR images in patients with diabetic neuropathic arthropathy of the foot were examined by two reviewers in consensus. Affected joints were examined for marrow, articular, periarticular, and soft-tissue findings. Presence of superimposed osteomyelitis was documented. A subgroup that had undergone MR before infection was evaluated for comparison; chi(2) and t tests were used to evaluate the associations.

RESULTS

Of 128 neuropathic joints in 63 patients (24 female, 39 male; aged 31-78 years), 43 had superimposed osteomyelitis. Effusion was common in all neuropathic joints, but thin rim enhancement was more common in noninfected joints (62% vs 21%, P < .001) and diffuse joint fluid enhancement was more common with infection (47% vs 26%, P = .052). Subluxation, bone proliferation, fragmentation, and erosion were seen in both groups, but intraarticular bodies were more common in noninfected joints (53% vs 12%, P < .001). In the periarticular soft tissues, edema, enhancement, and ulceration were common in both groups. Fluid collections in the soft tissues were more commonly associated with infected joints (95% vs 48%, P < .001) and, when present next to an infected joint, were larger than those next to noninfected neuropathic joints (2.6 cm(2) [range, 0.3-8.6 cm(2)] vs 1.6 cm(2) [range, 1.0-2.4 cm(2)]). Soft-tissue fat replacement (68% vs 36%, P = .002) and sinus tracts (84% vs 0%, P < .001) were also more common with infection. In the marrow, periarticular signal intensity abnormality was common in both groups, but the extent was greater with infection. Subchondral cysts were seen almost exclusively in noninfected joints (76% vs 2%, P < .001). Similar results were obtained in the subgroup of 21 joints (15 patients) with both pre- and postinfection MR images.

CONCLUSION

Sinus tract, replacement of soft-tissue fat, fluid collection, and extensive marrow abnormality are MR imaging features indicating superimposed infection. Thin rim enhancement of effusion, presence of subchondral cysts, or intraarticular bodies indicate absence of infection.

MR imaging of the diabetic foot

Diabetes is a common disease with potentially devastating complications affecting the foot and ankle. Ischemia and infarction, neuropathic osteoarthropathy, callus, ulceration, and infection result from the underlying neurologic and vascular disease. The MR imaging appearance of these complications is discussed. Recognition of these MR imaging patterns is important for formulation of an appropriate treatment plan.

Regional musculoskeletal conditions: foot and ankle disorders

Foot pain is very common, especially in women, owing to inappropriate footwear. Overuse, repetitive strain and minor, easily forgettable injuries may result in chronic foot and ankle pain. Rheumatoid arthritis, spondyloarthropathies and gout frequently affect the foot, often as a first presentation. Charcot's joints and foot infections are not rare in diabetes. The rheumatologist should be familiar with foot disorders, either localized or as manifestations of generalized disease. History taking, physical examination, identification of the source of pain by intra-articularly given local anaesthetics and imaging methods should be used to reveal the underlying disorder. Correct diagnosis and efficient therapy-including local steroid injections, physiotherapy, orthoses, surgery-are necessary not only for treatment but also for preventing biomechanical chain reactions. This chapter gives an overview of the epidemiology, diagnosis and treatment of foot pain and foot disorders caused by both local and generalized diseases.

Work-up of the diabetic foot

Diabetes is a common disease with potentially devastating complications affecting the foot and ankle. A combination of vascular disease, peripheral neuropathy, and immunopathy results in a cascade of conditions including ischemia and infarction, tendinopathy, atrophy, edema, deformity, neuropathic osteoarthropathy, callus, ulceration, and infection. MRI is useful for evaluation of these complications, and assists the clinician in medical or surgical planning.

Pedal abscesses in patients suspected of having pedal osteomyelitis: analysis with MR imaging

PURPOSE

To document the expected frequency, location, and size of pedal abscesses in patients with advanced foot infection.

MATERIALS AND METHODS

Images obtained at contrast material-enhanced magnetic resonance (MR) imaging (at 1.5 T) of 161 feet of 51 women and 107 men (mean age, 58.5 years; 82.3% had diabetes) who underwent bone biopsy after MR imaging for possible osteomyelitis were reviewed by two musculoskeletal radiologists working together. Presence, size, and location of abscesses and presence of adjacent skin ulceration were noted. MR imaging criteria for abscess were the following: presence of fluid collection with isointense or hypointense signal on T1-weighted images, fluid-equivalent signal intensity on T2-weighted images, and peripheral rim enhancement. All patients' charts were reviewed for clinical and surgical information.

RESULTS

Thirty-two fluid collections compatible with abscesses were found in 29 (18.4%) of the 158 patients; 26 (90%) of these patients had diabetes (P =.38). Abscess size varied from 1 x 0.5 x 0.4 cm to 3.8 x 3.4 x 2.2 cm (mean = 2.6 x 1.5 x 0.9 cm). Abscesses were located in the forefoot (n = 15), hindfoot (n = 7), toes (n = 3), midfoot (n = 4), or in multiple locations (n = 3). Thirty-one abscesses (97%) occurred near a skin ulcer (distance range, 0-9.1 cm; mean, 1.4 cm). Abscesses were significantly more frequent in patients with osteomyelitis (n = 28, 97%) (P <.001) and in feet that had been treated surgically (n = 16, 33%) (P <.002).

CONCLUSION

MR imaging revealed abscesses, predominantly in the forefoot, in 18% of patients suspected of having pedal osteomyelitis. Abscesses are significantly more frequent in patients with osteomyelitis and in feet that have been treated surgically.

Is soft-tissue inflammation in pedal infection contained by fascial planes? MR analysis of compartmental involvement in 115 feet

OBJECTIVE

The purpose of this study was to analyze compartmental involvement and patterns of spread of soft-tissue inflammation in pedal infection.

MATERIALS AND METHODS

We reviewed 115 contrast-enhanced 1.5-T MR examinations of the foot in 41 women and 74 men with a mean age of 58.4 years who had undergone bone biopsy or surgery for suspected osteomyelitis. Presence of inflammation (contrast enhancement, fat signal intensity loss on T1-weighted images, and high signal intensity on T2-weighted images) was noted by two musculoskeletal radiologists in the following foot compartments: toes, medial, central, lateral, interosseous, dorsal, hindfoot, malleoli, and lower leg. Proximal and distal extension of soft-tissue inflammation was analyzed. The compartment closest to the ulcer that showed MR signs of direct contiguous infection was designated the primarily infected compartment.

RESULTS

Spread of inflammation across fascial planes into neighboring compartments originated from the following primary compartments: medial (3/10, 30%), central (7/16, 44%), and lateral (16/20, 80%). Spread from the hindfoot and malleoli into adjacent compartments was seen in only 7% of such cases (2/24). Inflammation from toe infections spread in 34% of cases to forefoot compartments (15/44). Inflammation from forefoot or toe infections spread in 4.5% of cases to the midfoot and in 2% of cases to the hindfoot; ascension into the calf was rare (1% of cases). Spread of inflammation into neighboring compartments was not correlated with the presence of diabetes (p = 0.81) or with osteomyelitis (p = 0.34).

CONCLUSION

Soft-tissue inflammation of the forefoot tends to spread into neighboring compartments, with little respect for fascial planes. Hindfoot inflammation tends to stay confined. Spread from the foot to the lower leg is rare.

Magnetic resonance imaging of the forearm: cross-sectional anatomy in a cadaveric model

RATIONALE AND OBJECTIVES

Compartmental anatomy of the forearm is complex and controversial. The purpose of this investigation was to demonstrate via magnetic resonance the anatomy of forearm compartments and their preferential ways of communication in a human cadaveric model.

METHODS

Twelve forearm spaces (11 muscles and one intermuscular) were injected with a solution containing gadopentetate dimeglumine. The extent and distribution of leakage were evaluated on axial fat-suppressed T1-weighted spin-echo images. The findings were related to known descriptions of compartmental anatomy of the forearm.

RESULTS

Contrast leakage occurred mostly into the intermuscular space and into the muscles adjacent to the injected muscle. A frank communication within the classically described three forearm compartments (volar, radial, and dorsal) was not present. The interosseous membrane was not an absolute barrier between flexor and extensor compartments.

CONCLUSION

The classic description of three forearm compartments may not be sufficient to explain distribution of soft tissue abnormalities.

MRI of the foot and ankle

The foot and ankle are among the hardest of all areas to image because of the complex three-dimensional anatomy. Magnetic resonance imaging (MRI), with its multiplanar capabilities, excellent soft-tissue contrast, ability to image bone marrow, noninvasiveness, and lack of ionizing radiation, has become a valuable tool in evaluating patients with foot and ankle problems. MRI is more specific than bone scintigraphy and provides more information than ultrasound and computed tomography. Arthroscopy of the ankle is limited to the articular surface and joint space. MRI allows a global evaluation of the bones, tendons, ligaments, and other structures with a single examination that exceeds the capabilities of all other available techniques. This monograph was written to provide a useful guide to basic technique, indications, positioning, anatomy, and interpretation of foot and ankle MRI. The first part describes the performance of the MRI examination with reference to the positioning of the foot, types of coils, and advantages and disadvantages of the different sequences and imaging planes. The next section was written by an experienced foot and ankle orthopedic surgeon and outlines the indications for MRI for the common foot and ankle symptom complexes and the information that the surgeon hopes to obtain from the study. This is followed by a review of pertinent anatomy, as it applies to imaging, with emphasis on osseous structures, ligaments, tendons, and muscles. The final section is a comprehensive review of the common pathologic conditions encountered in the foot and ankle. We hope that radiologists and radiologists-in-training find this article a useful reference tool and gain a better understanding of this complex area of musculoskeletal imaging.

The calcaneus: applications of magnetic resonance imaging

The calcaneus is the largest bone in the foot and is an important primary weightbearing structure. Pathologic processes that affect this bone may manifest in a variety of clinical presentations, including pain, abnormal motion, instability, or fracture. The purpose of this article is to present a pictorial essay of the wide spectrum of pathologic entities that may affect the calcaneus, emphasizing applications of magnetic resonance imaging and characteristic magnetic resonance features of these processes.