Various proton relaxation times (T2, T1ρ, and gadolinium‐diethylene triamine pentaacetic acid [Gd‐DTPA]‐enhanced T1) were measured in articular cartilage in vitro at 3 T to assess their role in visualizing proteoglycan depletion. Cartilage‐bone specimens were obtained from patients who underwent total joint replacement and got a double dose of Gd‐DTPA 2 hours prior surgery. In these specimens, regions of mechanically undamaged cartilage having a decreased content of proteoglycans showed about 15% lower T1 values compared with apparently normal cartilaginous tissue. The expected increase of the T2 relaxation time was not observed in these regions. On the other hand, the T2 and, to a lower degree, T1 relaxation times were found to be increased in regions of cartilage fibrillation. The T1ρ relaxation times obtained were slightly longer than the corresponding T2 values, but both parameters showed almost identical spatial distributions. J. Magn. Reson. Imaging 1999;10:497–502. © 1999 Wiley‐Liss, Inc.
Various proton relaxation times (T2, T1, and gadolinium-diethylene triamine pentaacetic acid [Gd-DTPA]-enhanced T1) were measured in articular cartilage in vitro at 3 T to assess their role in visualizing proteoglycan depletion. Cartilage-bone specimens were obtained from patients who underwent total joint replacement and got a double dose of Gd-DTPA 2 hours prior surgery. In these specimens, regions of mechanically undamaged cartilage having a decreased content of proteoglycans showed about 15% lower T1 values compared with apparently normal cartilaginous tissue. The expected increase of the T2 relaxation time was not observed in these regions. On the other hand, the T2 and, to a lower degree, T1 relaxation times were found to be increased in regions of cartilage fibrillation. The T1 relaxation times obtained were slightly longer than the corresponding T2 values, but both parameters showed almost identical spatial distributions. J. Magn. Reson. Imaging 1999;10:497-502. A LOSS OF PROTEOGLYCANS in articular cartilage is one of the characteristics of early osteoarthritis (1-3). However, an MRI method for reliable and sensitive detection of the decrease in the proteoglycan content, before structural changes in cartilage develop, is not yet available. Several attempts have been made to visualize the loss of proteoglycans in articular cartilage using various MR techniques, particularly diffusion constants and magnetization transfer ratios. In vitro studies have shown effects of enzymatic removal of proteoglycans on the apparent diffusion constant (4,5); however, different enzymes induced inconsistent changes of this parameter (5). Furthermore, the effect of proteoglycan degradation on magnetization transfer parameters has not yet been fully explained (6,7). Recently, three different MR techniques, based on the measurement of longitudinal and transverse relaxation times, have been reported. Dardzinski et al (8) showed a reproducible pattern of increasing T2 relaxation time that was proportional to the distribution of cartilage water and was inversely proportional to the concentration of proteoglycans. They also demonstrated an increase of T2 in damaged cartilage. On the other hand, Duvvuri et al (9) suggested that the T1 relaxation time, rather than T1 and T2, is selectively sensitive to proteo-glycan content in articular cartilage. The possibility of quantifying the proteoglycan concentration in cartilage by means of the gadolinium-diethylene triamine pen-taacetic acid (Gd-DTPA)-enhanced T1 relaxation was shown by Bashir et al (10,11). They found that the preferential accumulation of the negatively charged contrast agent in cartilage with decreased proteoglycan content caused a diminution of proton T1 compared with normal tissue. It was also observed that after intravenous administration of Gd-DTPA the enhancement came from both the cartilage surface and the subcondral bone (12). In this work, we compared the techniques based on the measurement of relaxation times using in vitro samples of pathological cartilage. In ...
Between 1974 and 1985, 59 patients (83 feet) underwent basal closing wedge osteotomy in combination with a bunionectomy and a lateral soft tissue release for correction of hallux valgus and metatarsus primus varus at this institution. Of the original 59 patients, 42 patients (60 feet) with at least 10 years of follow-up (average, 194 months; range, 144-266 months) were available for this study. Results were analyzed by review of the medical records and plain radiographs, a standardized clinical questionnaire, and physical examination. Of the 60 feet, patients rated outcomes as excellent or good in 51 feet (85%) and rated cosmesis as excellent or good in 44 feet (73%). Radiographically at final follow-up, hallux valgus and intermetatarsal angles averaged 19.9 degrees (range, 0-40 degrees) and 6.7 degrees (range, 0-18 degrees), respectively. The sesamoid position was corrected from an average preoperative grade of 2.6 to a grade of 0.9 at final follow-up. The average shortening of the first metatarsal was 5 mm. The disadvantages of the closing wedge osteotomy are that it is technically demanding and it entails the risk of shortening, dorsal malalignment, and metatarsalgia. In the current study, long-term complications included hallux varus deformity (16 feet), dorsal malalignment (15 feet), and metatarsalgia (14 feet). Despite good correction of the intermetatarsal angle and sesamoid position, the clinical results and the incidence of complications after basal closing wedge osteotomy were not as favorable as those reported for other procedures in the literature. Therefore, alternative procedures, such as the basal crescentic osteotomy or the basal chevron osteotomy, should be used.
The Austin osteotomy is a widely accepted method for correction of mild and moderate hallux valgus. In view of publications by Kitaoka et al. in 1991 and by Mann and colleagues, a more radical lateral soft tissue procedure was added to the originally described procedure. From September 1992 to January 1994, 85 patients underwent an Austin osteotomy combined with a lateral soft tissue procedure to correct their hallux valgus deformities. Seventy-nine patients (94 feet) were available for follow-up. The average patient age at the time of the operation was 47.1 years, and the average follow-up was 16.2 months. The average preoperative intermetatarsal angle was 13.9 degrees, and the average hallux valgus angle was 29.7 degrees. After surgery, the feet were corrected to an average intermetatarsal angle of 5.8 degrees and an average hallux valgus angle of 11.9 degrees. Sesamoid position was corrected from 2.1 before surgery to 0.5 after surgery. The results were also graded according to the Hallux Metatarsophalangeal Interphalangeal Score, and the functional and cosmetic outcomes were graded by the patient. Dissection of the plantar transverse ligament and release of the lateral capsule repositioned the tibial sesamoid and restored the biomechanics around the first metatarsophalangeal joint. There was no increased incidence of avascular necrosis of the first metatarsal head compared with the original technique.
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