Analysis of the heel pad fat in rheumatoid arthritis.

The heel fat pad is organized, both in structure and in composition, to bear the stresses and strains of normal activities and to permit pain-free weightbearing. The fatty acid composition of heel pads in 11 patients with rheumatoid arthritis, a disease process frequently associated with heel fat pad atrophy, was analyzed using gas-liquid chromatography and was compared with that of patients without systemic disease. The heels of patients with rheumatoid arthritis demonstrated a significant change in the composition of saturated fatty acids when compared with heels of nonrheumatoid patients. This composition reflects an increased fat viscosity, which decreases the ability of the heel to absorb and dissipate the energy generated during ambulation. This factor could cause degeneration of the heel septal system, with resulting fat pad atrophy.

MR imaging of flexor digitorum accessorius longus.

OBJECTIVE: The flexor digitorum accessorius longus muscle (FDAL), an anomalous muscle about the ankle, has recently been implicated in tarsal tunnel syndrome. The purpose of this study is to document the prevalence of the FDAL, its MR appearance and its relation to the neurovascular bundle in the tarsal tunnel. DESIGN AND PATIENTS: The prevalence of the FDAL was determined from 100 ankle MR examinations in asymptomatic individuals. The appearance of the FDAL was summarized from 20 examples of FDAL: six gathered from the asymptomatic group and 14 acquired from a group of randomly collected cases of patients with ankle complaints. RESULTS: The prevalence of the FDAL was 6%, calculated from the group of 100 asymptomatic individuals. Possessing a dominant fleshy component in the tarsal tunnel, the FDAL accompanies the posterior neurovascular bundle as it descends the ankle. CONCLUSION: The FDAL is encountered in 6% of asymptomatic individuals. Its prominent fleshy component in the tarsal tunnel and its close proximity to the posterior tibial neurovascular bundle readily differentiate the FDAL from other medial anomalous muscles on MR imaging.

Peroneus quartus muscle: MR imaging features.

PURPOSE: To determine the prevalence of the peroneus quartus (PQ) muscle, to demonstrate the morphology of this accessory muscle on magnetic resonance (MR) images, and to reassess the reported association of the PQ muscle with a hypertrophic peroneal tubercle. MATERIALS AND METHODS: A retrospective review was performed of 136 consecutive ankle MR imaging studies. The origins, insertions, and variations in size of the muscle and the dimensions of the peroneal tubercle and retrotrochlear eminence were recorded. RESULTS: The prevalence of the PQ muscle was 10% (14 of 136 cases). The accessory muscle and tendon unit descended medial and posterior to the peroneal tendons. The site of insertion was variable and included the calcaneus, peroneus longus tendon, peroneus brevis tendon; and cuboid bone. The calcaneus was the insertion site in 11 cases. The accessory tendon attached to the retrotrochlear eminence of the calcaneus. In the group with the PQ muscle, the retrotrochlear eminence was significantly taller (P < .01) than in the group without the PQ muscle. CONCLUSION: Contrary to previous reports, the peroneocalcaneal variant of the PQ muscle appears to insert in the retrotrochlear eminence of the calcaneus rather than the peroneal tubercle. The presence of the PQ muscle is associated with a prominent retrotrochlear eminence but not with an enlarged peroneal tubercle.

Posterior intermalleolar ligament of the ankle: normal anatomy and MR imaging features.

OBJECTIVE: The purposes of this study were to delineate the normal anatomy and MR imaging features of the posterior intermalleolar ligament--a normal ligamentous variant of the posterior portion of the ankle--and to identify normal anatomic characteristics that may account for the role of the ligament in the development of posterior impingement syndrome. MATERIALS AND METHODS: The prevalence, size, and shape of the posterior intermalleolar ligament were documented in 36 cadaveric ankles and in 97 MR studies of the ankle in patients with and without symptoms. RESULTS: The posterior intermalleolar ligament was identified in 20 (56%) of the 36 cadaveric feet. It was 1-8 mm wide, and its diameter (anterior to posterior) was 5-8 mm. The ligament often resembled a meniscus, and in one case its anterior lip herniated into the ankle joint. The posterior intermalleolar ligament was detected in 18 (19%) of the 97 MR studies of the ankle. It was visualized on coronal T1- or T2-weighted images as a distinct, hypointense band traversing between the posterior talofibular ligament and the inferior transverse ligament. CONCLUSION: The posterior intermalleolar ligament is a normal variant of the posterior ligaments of the ankle and is present in a significant number of persons. It is best seen on coronal T1- and T2-weighted MR images. Its meniscuslike shape and occasional extension into the ankle joint may account for the development of posterior impingement syndrome in susceptible persons.

Histology and histomorphometric analysis of the normal and atrophic heel fat pad.

Light and electron microscopy was used for a histologic examination of normal heel fat pads and atrophic heel fat pads from patients with peripheral neuropathies. Histomorphometric analysis revealed an average 30% smaller mean cell area and 16% smaller mean cell diameters in the atrophic pads compared with the normal heel fat pads. Septal walls in the atrophic fat pads were often fragmented and approximately 75% wider than normal. Perineural fibrosis was also found in the atrophic heel fat pads. The Verhoeff elastic staining technique was used to determine the relative percentage of collagen to elastic tissue within the septae. No significant differences were noted between the normal and atrophic heels. The ultrastructure of the adipocytes from the normal and atrophic heel pads was similar to those found in abdominal subcutaneous fat. Lipid droplets of variable size and density thin the center of the adipocyte were surrounded by a thin border of cytoplasm. The interphase between adipocytes contained fine collagen and elastic fibers.

Deltoid ligament forces after tibialis posterior tendon rupture: effects of triple arthrodesis and calcaneal displacement osteotomies.

Deltoid ligament forces were studied after observing deltoid ligament insufficiency in several post-triple arthrodesis patients. Six fresh-frozen, below-knee amputation specimens were axially loaded. The results demonstrate that a properly positioned triple arthrodesis produced deltoid ligament forces that were similar to those seen with an intact tibialis posterior tendon. A triple arthrodesis in combination with a lateral displacement calcaneal osteotomy produced deltoid ligament forces that were 76% greater than those seen with the intact tibialis posterior tendon (P < .05). A triple arthrodesis in combination with a medial displacement calcaneal osteotomy produced deltoid ligament forces that were 56% less than those seen with the lateral displacement calcaneal osteotomy (P < .01). Patients with longstanding ruptures of the tibialis posterior tendon and associated peritalar subluxation/dislocation may have less than optimal clinical results after triple arthrodesis, unless the hindfoot can be properly reduced, due to persistent elevated forces in the deltoid ligament and resulting ligament laxity. This study suggests that a medial displacement calcaneal osteotomy in combination with a triple arthrodesis may be a viable treatment when the hindfoot cannot be positioned properly.

Clinical significance of magnetic resonance imaging of the ankle and foot.

Magnetic resonance imaging is of major diagnostic value in foot and ankle pathology. It is noninvasive and extremely accurate, and rarely gives false negative or false positive results. Any false results are due invariably to poor imaging, or inept interpretation by the radiologist or orthopedist or both. Diagnostic accuracy is increased by clinical correlation. Magnetic resonance imaging is not only a valuable diagnostic tool with respect to the foot and ankle but also is often of great value in either indicating or contraindicating surgery or modifying the preoperative surgical management. Finally, the orthopedist must be aware of the current limitations of MR imaging and not assume that a negative reading indicates the absence of pathology.

Fatty acid composition of normal and atrophied heel fat pad.

Capillary gas-liquid chromatography was used to analyze the fatty acid composition of normal heel fat pads from subjects without systemic disease (N = 8) and atrophied heels from patients with diabetic peripheral neuropathy (N = 4), rheumatoid arthritis (N = 1), peripheral vascular disease (N = 1), and hereditary sensory neuropathy (N = 1). In the normal subjects, the fatty acid composition of subcutaneous abdominal fat was also obtained for comparison. Three saturated fatty acids (myristate, palmitate, and stearate) and four unsaturated fatty acids (palmitoleate, oleate, vaccenate, and linoleate) comprised over 90% of the total fatty acid composition. Higher percentages of unsaturated fatty acids and lower percentages of saturated fatty acids were found in the normal heel fat pads when compared to subcutaneous abdominal fat. The increase in the ratio of unsaturated fatty acids to saturated fatty acids (4.4 versus 2.5, P < .01) may decrease triglyceride viscosity and enhance the biomechanical efficiency of the heel fat pad. Though the number of patients is small, no statistically significant compositional differences were noted between the heel fat from normal subjects and from subjects with peripheral neuropathies, rheumatoid arthritis, or peripheral vascular disease. However, the heel fatty acid composition of the one subject with a hereditary sensory neuropathy was less unsaturated and more saturated than normal with a ratio of unsaturates to saturates similar to that of the abdomen (2.8).

Investigations into the fat pads of the sole of the foot: anatomy and histology.

Anatomical, histological, and histochemical studies were performed on normal and abnormal fat pads of the sole of cadaver feet. The fat pads were found to contain a significant nerve and blood supply separate from that to the surrounding musculature and skin. Pacinian corpuscles and free nerve endings within the fat were identified. Histological analysis indicated a meshwork of fibroelastic septae arranged in a closed-cell configuration. The mechanical consequences of this organization are discussed in the context of the weightbearing role of the fat pads of the feet. Alterations seen in dysvascular or senescent feet are consistent with the hypothesis that the septal anatomy of the fat pads is central to their cushioning function.

Investigations into the fat pads of the sole of the foot: heel pressure studies.

The fat pads of the heel have a structure that is optimized for load bearing. In various diseases and aging, the load-carrying ability of the heel pad is clinically impaired. The loading pattern was examined in subjects having normal heel pads and those with atrophic heel pads, both with and without clinical symptoms. Normal heel pads showed a broad region of high pressure, which accounted for a high percentage of the total load transmission. In contrast, the atrophic heels showed a high but narrow peak pressure. However, most of the load was transmitted over a large area of low pressure. There was no difference between symptomatic and asymptomatic heels. The mechanical behavior of the fat pad is discussed with particular reference to the anatomic structure of the pads. Pad thickness and septal integrity are both important to the mechanical characteristics of the fat pad. The load-bearing patterns observed are discussed in terms of the mechanical components influencing fat pad resilience. These results have direct relevance to understanding the pathophysiology of heel pain secondary to degeneration of the fat pad.

Clinical significance of magnetic resonance imaging in preoperative planning for reconstruction of posterior tibial tendon ruptures.

A retrospective study of attenuated/ruptured posterior tibial tendons was conducted of all patients who underwent tendon reconstruction over a 4-year period. The study comprised 20 feet in 19 patients having an average age of 53.3 years, with an average follow-up of 2 years. Preoperative magnetic resonance images were taken and graded for assignment to one of three magnetic resonance imaging (MRI)-based groups. The surgical grade was determined intraoperatively based on a previously described classification scheme. No medical or rheumatologic conditions predisposing to failure could be identified. Failure was defined as postoperative progression of pain and deformity which required subsequent triple arthrodesis. There were six failures at an average of 14.7 months. Surgical evaluation was not correlated to outcome following reconstruction. MRI grading, however, was predictive of outcome. The superior sensitivity of MRI for detecting intramural degeneration in the posterior tibial tendon that was not obvious at surgery may explain why MRI is better than intraoperative tendon inspection for predicting the outcome of reconstructive surgery. Therefore, it may be helpful to obtain preoperative MRI when this particular reconstruction of the posterior tibial tendon is contemplated, since this provides the best measure of tendon integrity and appears to be the best predictor of clinical success after such surgery.

Foot and ankle pain resulting from rheumatic conditions.

Pain in the foot and ankle is most frequently secondary to static and degenerative changes, eg, corns, hammer toes, bunions, anterior metatarsalgia, and heel pain. A second common group consists of rheumatologic disorders that encompass immune and hereditary factors. This group includes rheumatoid arthritis, the often underdiagnosed seronegative spondyloarthropathies, and, less commonly, crystalline deposit disorders and diffuse connective tissue diseases. Both the physician and the public need a heightened awareness of the existence and presence of these disorders, which may be devastating, eg, psoriatic arthritis and tenosynovitis. To these groups, we now must add Lyme disease and acquired immunodeficiency syndrome. The advances in testing, including immunologic and nuclear imaging (eg, magnetic resonance imaging), have permitted more rapid and specific diagnosis with earlier treatment.

Magnetic resonance imaging of anomalous leg muscles: accessory soleus, peroneus quartus and the flexor digitorum longus accessorius.

Since the availability of magnetic resonance imaging (MRI), the suspected diagnosis of an accessory muscle of the lower extremity can now be confirmed without the need for invasive procedures. The accessory soleus, peroneus quartus, and flexor digitorum longus accessorius are anomalous muscles of the lower extremity that can be diagnosed by MRI. These accessory muscles are probably more common than once thought and can now be easily distinguished from other space occupying lesions that can occur around the ankle. MRI of these anomalous muscles enables one to make a definitive diagnosis without a biopsy. In those symptomatic patients, the origins and insertions of these accessory muscles can be accurately evaluated by MRI prior to any anticipated surgical intervention.

The Akin procedure: an analysis of results.

This paper reports the initial and long-term results of 45 Akin procedures done at the Hospital for Joint Diseases/Orthopaedic Institute from 1966 to 1985. Indications for 36 of the 45 operated feet were for an essentially asymptomatic great toe valgus deformity which caused symptoms to develop in the second toe and in 9 of 45 feet for residual hallux valgus after previous hallux valgus surgery. Excellent and good results were reported in 89% of the patients. The most common technical problem reported in 22% of the patients was plantar angulation at the osteotomy site. The only technical problem that was associated with long-term complications was bone apposition of less than 50% which may have lead to a nonunion in one case and recurrence of deformity in another. Shortening of the hallux was observed in all cases secondary to the closing wedge osteotomy. Shortening can be limited if a minimum of bone is removed from the proximal phalanx. A mathematical analysis is presented in this paper which can be used to provide guidelines to osteotomy size so that a minimum of bone necessary for correction can be removed. The Akin procedure should be performed within certain guidelines. Rarely is an Akin procedure alone indicated for the correction of a hallux valgus deformity. In most patients the proximal phalangeal osteotomy needs to be performed in combination with some other procedure to correct all components of the hallux valgus deformity. Furthermore the procedure can be used with success in those patients who present with an essentially asymptomatic great toe valgus deformity at the metatarsophalangeal joint or the interphalangeal joint which causes symptoms and/or deformity to develop in the second toe.(ABSTRACT TRUNCATED AT 250 WORDS)

Tibialis posterior: a review of anatomy and biomechanics in relation to support of the medial longitudinal arch.

The medial longitudinal arch is unique among homo sapiens. This specialization of the human foot is believed to be necessary to the habitual bipedal gait pattern. Mechanical integrity of the arch depends on static and dynamic anatomic factors. The posterior tibial tendon in particular is situated to provide dynamic support along the plantar aspect of the foot and arch. Evaluation of the phasic activity of the posterior tibial muscle appears to confirm this premise. Furthermore, changes in the longitudinal arch that occur when the posterior tibialis is deficient lend further evidence that it is important in maintenance of the normal arch.

Rupture of posterior tibial tendon: CT and MR imaging with surgical correlation.

Computed tomography (CT) and magnetic resonance (MR) imaging were performed in 32 cases of clinically suspected chronic tears of the posterior tibial tendon. Surgery was performed in 22 patients (69%). Each case was classified radiographically and surgically as normal or a type 1, type 2, or type 3 rupture. The sensitivity and specificity of CT were 90% and 100%, respectively, while those of MR imaging were 95% and 100%. The accuracy in detecting ruptures was 91% for CT and 96% for MR imaging. The overall accuracy, which reflected the percentage of cases correctly diagnosed as well as those correctly classified, was 59% for CT and 73% for MR imaging. Although the differences between the CT and MR imaging parameters were not statistically significant (possibly due to the small population), the results suggest that MR imaging is the method of choice for detecting ruptures of the posterior tibial tendon. MR imaging provided greater definition of tendon outline, vertical splits, synovial fluid, edema, and degenerated tissue. CT was superior to MR imaging in showing associated bone abnormalities such as periostitis, subtalar osteoarthritis, and subtalar dislocation.

Computed tomography scan and magnetic resonance imaging of ankle tendons: an overview.

CT and MRI are both effective in the diagnosis of ankle tendon injuries. MRI is the preferred study, however, because of its superior soft tissue contrast resolution, multiplanar capabilities, lack of beam hardening artifacts, and lack of ionizing radiation. CT can serve as an excellent substitute when financial considerations and availability preclude the use of MRI. CT is also superior in evaluating bony abnormalities associated with tendon injuries.

Rupture of the posterior tibial tendon: CT and surgical findings.

Computed tomography (CT) was performed in 42 patients with 49 clinically suspected tears of the posterior tibial tendon. Twenty-eight of the 49 suspected tears were subsequently surgically explored and repaired. Three patterns of tendon abnormalities were recognized on CT scans: type I-intact, hypertrophied, heterogeneous tendon; type II-attenuated tendon; and type III-absence of a portion of a tendon. Types I and II correlated with partial rupture seen during surgery, and type III correlated with complete rupture of the tendon. CT findings were accurate in 96% of the patients who underwent surgery. In four cases (14%), tendon rupture was seen on CT scans, but the extent of the injury was underestimated and the rupture was misclassified. Reactive periostitis of the distal tibia was seen in 71% of diseased tendons and may represent an important factor in the diagnosis of tendon rupture.