Simulated weightbearing computed tomography for verification of radiographic staging of varus ankle osteoarthritis: a cross-sectional study.

BACKGROUND: Varus ankle osteoarthritis is classified using only weightbearing anteroposterior ankle radiographs; however, sagittal ankle alignment may also affect the position and extent of joint space obliteration. We hypothesized that the sagittal alignment of the ankle may also affect the position and extent of joint space obliteration visible on the coronal section; therefore, we identified the sites of joint space obliteration in patients with stage 3 varus ankle osteoarthritis for comparison with the sites observed on simulated weightbearing computed tomography and investigated the effects of anterior and posterior ankle subluxation. METHODS: Simulated weightbearing computed tomography scans of 83 ft with varus ankle osteoarthritis (26 stage 3a, 57 stage 3b) were performed to check for joint space obliteration in the ankle. Further classification as exhibiting either anterior, posterior, or no subluxation on weightbearing lateral radiographs was performed. RESULTS: Anterior, posterior, and no subluxation was seen in 5, 9, and 12 ankles among the 26 classified as stage 3a, respectively, and in 22, 12, and 23 ankles among the 57 classified as stage 3b, respectively. The mean tibial lateral surface angle on weightbearing lateral radiographs in stage 3a ankles was 75.6, 83.3, and 80.3 degrees in the anterior, posterior, and no subluxation groups, respectively; and 75.5, 86.6, and 82.7 degrees in stage 3b ankles (p < .05). In stage 3b ankles, widespread joint space obliteration was observed at the anterior distal articular surface of the tibia in all 22 ankles with anterior subluxation and at the posterior distal articular surface of the tibia in all 12 ankles with posterior subluxation. CONCLUSIONS: Simulated weightbearing computed tomography revealed joint space obliteration at the anterior distal articular surface of the tibia in stage 3b ankles with anterior subluxation and at the posterior side in stage 3a and 3b ankles with posterior subluxation. In some patients with stage 3 varus ankle osteoarthritis, the obliteration of the joint space is difficult to evaluate accurately using only weightbearing anteroposterior radiographs; weightbearing lateral radiographs should also be performed.

Helical conformation endows poly-l-lactic acid fibers with a piezoelectric charge under tensile stress.

Poly-l-lactic acid (PLLA) has been clinically used as a bioabsorbable material and attains a piezoelectric charge upon molecular orientation by the application of a shear force to the C-axis of the crystal line region. Previous studies showed that implanted drawn PLLA films or rods accelerate the ossification due to piezoelectric effect. In this study, we originally designed helically-twisted PLLA fiber to produce piezoelectricity in bioabsorbable suture upon tensile stress. The piezoelectricity of the helical PLLA fibers was evaluated using a lock-in amplifier system in vitro. The ossification induced by helical PLLA fibers was examined by implanting them in the rat patellar ligament supporting a physiological tensile load. We observed that 57° and 45° twisted PLLA fibers generated a higher piezoelectric potential than did 27° twisted fibers. The animal experiment showed that the formation of osseous tissue around helical PLLA fibers was more significant than around non-helical control fibers at 4 weeks after their implantation. These results suggest that helical PLLA fiber may be useful for the surgical suture or artificial ligament, which connects to the bone.

Cartilage thickness of the talar dome.

PURPOSE: To perform a successful operation, accurate information on the articular cartilage thickness of the talus is essential. The purpose of this study was to determine the articular cartilage thickness of the talar dome in the area where osteochondritis dissecans is common. TYPE OF STUDY: Convenient samples. METHODS: Articular cartilage thickness of the mid talar dome was measured in 29 ankles of 17 cadavers. The average age of the specimens was 70 years (range, 53 to 91 years). Twenty-two were from men and 7 were from women. Coronal sections of the mid talar domes were obtained from the specimens measuring 2 mm in width and 5 mm in depth. Radiographs of the sectioned specimens were taken and were enlarged with a personal computer. The thickness of the articular cartilage was measured at 9 areas: medial gutter (area 1), medial corner (area 2), medial edge of the dome plateau (area 3), lateral edge of the dome plateau (area 7), lateral corner (area 8), lateral gutter (area 9), and quarter points between areas 3 and 7 (areas 4, 5, and 6). RESULTS: The average thickness of the total areas was 1.35 +/- 0.22 mm in the male specimens and 1.11 +/- 0.28 mm in the female specimens. The thickest was area 2, which represented the medial corner, and the thinnest was area 9, which represented the lateral gutter in both men and women. There was a relationship between the thickness of the cartilage and the width of the talar dome. CONCLUSIONS: The thickness was usually less than 2 mm. However, the cartilage thickness varies widely by gender, area, and individual. CLINICAL RELEVANCE: Our report will help surgeons predict the volume of cartilage that needs to be repaired and produce treatment at a reasonable cost without an excessive invasion of patients.

Axial radiographic evaluation in hallux valgus: evaluation of the transverse arch in the forefoot.

To quantitatively evaluate the shape of the transverse arch in the forefoot with hallux valgus, a method for axial imaging and analysis of the forefoot has been developed. A foot was imaged at 30 degrees of flexion. A two-dimensional coordinate system was established by drawing a vertical line on the X-ray image through the lowest point of the head of the second metatarsal. The origin was set at the intersection between the plane of the base of the foot and this vertical line. A control group of 51 feet from 29 normal subjects and a test group of 59 feet from 34 subjects with hallux valgus were examined. Compared with the normal group, the heads of the first, second, and third metatarsal bones were lower in the hallux valgus group, and their sesamoids were shifted outward with a rotational deviation. There was a statistical correlation between the degree of outward dislocation of the fibular sesamoid bone and the hallux valgus angle. The position of the fibular sesamoid bone become higher than the head of the first metatarsal when the angle of the hallux valgus exceeded 25 degrees.

Anatomy of the spring ligament.

BACKGROUND: The spring ligament has been reported to be composed of the inferior calcaneonavicular and superomedial calcaneonavicular ligaments. We investigated the lower layer of the spring ligament fibrocartilage complex under the fibrocartilaginous surface, identified three distinct structures, and examined the morphology and running patterns of their fiber bundles. METHODS: Forty-eight cadaveric feet were examined. After ablation of the ankle joint and extirpation of the talus, the surface cartilage of the spring ligament fibrocartilage complex was carefully removed with forceps, and the length, width, and thickness of the three components of the complex were measured with calipers. RESULTS: The three components of the spring ligament complex are the superomedial calcaneonavicular ligament, the inferior calcaneonavicular ligament, and a structure that we termed the third ligament, which comprises fibers running from the notch between the calcaneal facets to the navicular tuberosity. CONCLUSIONS: We demonstrated a third component of the spring ligament; this component runs from the notch between the anterior and middle calcaneal facets to the tubercle of the navicular in the lower layer of the spring ligament complex, lying beneath the cartilaginous surface of the complex.

Pirogoff ankle disarticulation as an option for ankle disarticulation.

Eleven patients (12 ankles) who had Pirogoff ankle disarticulation were followed up for an average of 5.6 years (range, 2.1-8.9 years). After disarticulation of the Chopart joint, the talus was removed and the calcaneus was cut off in the coronal plane. The heel then was rotated 90 degrees to the tibial plafond. The postoperative result was evaluated using a scoring sheet. Excellent results were seen in four feet: two in patients with trauma, one in a patient with a metastatic tumor, and one in a patient with osteomyelitis. Good results were seen in two feet: one in a patient with trauma and one in a patient with diabetes mellitus. A fair result was seen in one foot in a patient with diabetes mellitus. Poor results were seen in four feet in three patients with arteriosclerosis and one foot in a patient with diabetes mellitus. In Pirogoff ankle disarticulation, the leg-length discrepancy is compensated for by using the calcaneus. The patients only had a leg-length discrepancy of 2.8 cm on average, which enabled them to walk outdoors wearing only a shoe orthosis. The postoperative results were unfavorable in patients with vascular diseases and were satisfying in patients without vascular diseases.

C sign for diagnosis of talocalcaneal coalition.

PURPOSE: To reevaluate the relevance of the C sign for diagnosis of talocalcaneal coalition. MATERIALS AND METHODS: Weight-bearing lateral radiographs of 55 feet with talocalcaneal coalition (patient group) and 55 feet without coalition (control group) were reviewed retrospectively. In the patient group, 36 cases of talocalcaneal coalition were confirmed histologically, and 19 cases that did not require surgery were diagnosed at computed tomography (CT). At CT, absence of talocalcaneal coalition in control subjects was confirmed, and control subjects were individually matched with patients according to sex, age, and the calendar year of the clinic visit. Two observers who were blinded to personal information regarding the subjects assessed the presence of the C sign on randomly presented radiographs. When judgments differed, a third observer made the final judgment. Affected feet were classified according to location (ie, medial, posterior, or diffuse) of the coalition and age (ie, <12, 13-20, >21 years). Sensitivity, specificity, and likelihood ratios of the C sign were calculated, and a second radiologic sign, posterior joint surface irregularity, was also evaluated. Differences in occurrence of the C sign among groups according to age and type of coalition were evaluated with the Fisher exact probability test. RESULTS: Sensitivity and specificity of the C sign for diagnosis of talocalcaneal coalition were 49% and 91%. The positive and negative likelihood ratios were 5.44 and 0.56, respectively. Corresponding sensitivity, specificity, and positive and negative likelihood ratios for the irregularity of the posterior talocalcaneal joint were 71%, 93%, 10.14, and 0.31, respectively. C-sign false-negative findings were more frequent in patients younger than 12 years and in those with posterior coalition. CONCLUSION: C sign sensitivity obtained in our study was low, which indicated that an absence of the C sign does not negate a diagnosis of coalition.