Bone density as a risk of early loss of correction after percutaneous posterior spinal fixation for traumatic thoracolumbar fracture: a study on the usefulness of Hounsfield unit values on computed tomography scan.

PURPOSE: Vertebral Hounsfield unit values on computed tomography scan (CT values) have been found to be correlated with bone density measured using dual-energy X-ray absorptiometry. We hypothesized that low preoperative CT values are risk factors for early loss of correction after percutaneous posterior spinal fixation (PPSF). This study aimed to evaluate the usefulness of measuring preoperative CT values. METHODS: In total, 104 patients underwent PPSF due to traumatic thoracolumbar fracture. Among them, 53 with a range of fixation that was within two vertebrae above and below the fractured vertebra were selected. CT values were measured preoperatively from the most cephalad vertebrae on the fixed vertebrae. Vertebral wedge angle (VWA) and local kyphosis angle (LKA) were measured before and after surgery. participants were classified into progression (P) and nonprogression (NP) groups. The P group comprised patients with LKA progressing > 10° from the immediate postoperative period to 3 months postoperatively. Meanwhile, the NP group included patients without progression. RESULTS: Eight (15.1%) patients were included in the P group. The vertebral CT values were 102.2 ± 36.7 in the P group and 162.4 ± 59.7 in the NP group (p < 0.01). The pedicle CT values were 114.4 ± 45.9 in the P group and 170.8 ± 72.3 in the NP group (p < 0.05). At 2 weeks postoperatively, VWA and LKA of the P group progressed to 9.8° ± 7.0° and 10.9° ± 7.6°, respectively. CONCLUSION: CT values can predict progressive loss of correction after PPSF.

Minocycline-induced periarticular black bones in inflamed joints which underwent arthroplastic reconstruction.

BACKGROUND: Minocycline-induced pigmentation of bone (black bone) is well described in tooth-bearing intra-oral bone, but is less known in periarticular bone in patients who have undergone total joint arthroplasty. On a retrospective basis, we investigated the short-term clinico-radiological results of total joint arthroplasties in which the patient developed minocycline-induced periarticular black bone. METHODS: We found 5 cases (0.08%), in 4 patients, of periarticular bone pigmentation revealed during total joint arthroplasties (2 hips, 2 knees, and 1 ankle) in our series of total joint surgeries (6,548 cases) over a 10-year time period in our 3 institutes. Their mean age was 56 years at surgery. All patients had received long-term minocycline treatment. Mean dosage and duration of minocycline was 160 mg/day and 2.2 years, respectively. Minocycline had been prescribed for reactive arthritis (one), rheumatoid arthritis (two) and late infection after total joint arthroplasty (two patients). Mean follow-up period was 3.4 years after the surgeries. RESULTS: All cases had black or brown pigmentation in the periarticular bones during the surgery. There was no pigmentation in the cartilage or soft tissues of the joints. The mean Japanese Orthopaedic Association (JOA) score or Japanese Society for Surgery of the Foot (JSSF) scale for rheumatoid arthritis foot and ankle joints at latest follow-up (case 1, 66; case 2, 87; case 3, 77; case 4, 77; case 5, 80) improved compared to those of pre-surgery (case 1, 47; case 2, 45; case 3, 55; case 4, 34; case 5, 55). No implant loosening was noted on radiographic examination during the follow-up period. No abnormal bone formation, bone necrosis, hemosiderin deposition, malignancy or metallic debris was found on histological examination. CONCLUSIONS: No clinico-radiological symptoms of total joint arthroplasties showed in the patients with minocycline-induced periarticular black bone in the short-term. Systemic minocycline treatment has the potential to induce significant black pigmentation of many tissues. In particular, minocycline-induced pigmentation of periarticular bone may be accelerated by inflammation due to rheumatic or pyogenic arthritis. Surgeons should recognize the risk of bone pigmentation in inflamed joints due to the systemic treatment of minocycline and explore its influence on periarticular bone and total joint arthroplasty in the long-term.

Distribution of myeloid dendritic cells and plasmacytoid dendritic cells in the synovial tissues of rheumatoid arthritis.

OBJECTIVE: To examine the precise tissue distribution of dendritic cells (DC) and indoleamine 2,3-dioxygenase (IDO)-expressing cells in synovial tissue and synovial fluid (SF) from patients with rheumatoid arthritis (RA) and osteoarthritis (OA). METHODS: Synovial tissues from 30 patients with RA and 7 with OA were immunohistochemically stained for DC markers. The examined areas were classified into 5 categories based on pathobiological staging and histopathological grading systems. Myeloid DC (mDC) and plasmacytoid DC (pDC) were isolated using positive and negative magnetic sorting systems, respectively, from SF samples (7 patients with RA and 4 with OA) and synovial tissues (3 RA, 4 OA). RESULTS: mDC were mainly observed in lymphoid aggregations. pDC were scattered around perivenular infiltration areas, and small and large lymphoid aggregations in RA. The mDC/pDC ratio increased significantly, with higher grading in RA SF tissues compared to OA synovial tissues (p<0.05). IDO-immunoreactivity was detected in pDC by serial sectioning and staining of RA synovial tissues. CONCLUSION: Our results indicate that mature mDC play a central role in the RA inflammatory process. Although there were fewer pDC than mDC, the presence of IDO-positive pDC suggests a possible tolerance mechanism in RA synovial tissues. However, it is probably modest due to the marked inflammation in RA, in which mDC are dominant.

CASE REPORTS: intraarticular fibroma of the tendon sheath in the knee.

We report a rare case of fibroma of the tendon sheath in the knee. To our knowledge, only three previous cases of fibroma of the tendon sheath in the knee have been reported in the English literature. In our case, T1-weighted magnetic resonance imaging revealed a low intensity signal, T2-weighted magnetic resonance imaging showed a mixed area of high and low signal intensity, and gadolinium-diethylene triaminepentaacetic acid-enhanced magnetic resonance imaging showed faint enhancement at the periphery of the lesion. Magnetic resonance imaging therefore was valid for detection of this intraarticular lesion. The lesion, which was located between the posterior capsule of the left knee and the posterior cruciate ligament, was excised arthroscopically.