Computed tomography osteoabsorptiometry-based investigation on subchondral bone plate alterations in sacroiliac joint dysfunction

Sacroiliac joint dysfunction (SIJD) is an underappreciated source of back pain. Mineralization patterns of the sacroiliac (SIJ) subchondral bone plate (SCB) may reflect long-term adaptations to the loading of the joint. Mineralization densitograms of 27 SIJD patients and 39 controls, were obtained using CT osteoabsorptiometry. Hounsfield unit (HU) values of the SCB mineralization of superior, anterior and inferior regions on the iliac and sacral auricular surfaces were derived and statistically compared between SIJD-affected and control cohorts. Healthy controls showed higher HU values in the iliac; 868 ± 211 (superior), 825 ± 121 (anterior), 509 ± 114 (inferior), than in the sacral side; 541 ± 136 (superior), 618 ± 159 (anterior), 447 ± 91 (inferior), of all regions (p < 0.01). This was similar in SIJD; ilium 908 ± 170 (superior), 799 ± 166 (anterior), 560 ± 135 (inferior), sacrum 518 ± 150 (superior), 667 ± 151 (anterior), 524 ± 94 (inferior). In SIJD, no significant HU differences were found when comparing inferior sacral and iliac regions. Furthermore, HU values in the inferior sacral region were significantly higher when compared to the same region of the healthy controls (524 ± 94 vs. 447 ± 91, p < 0.01). Region mineralization correlated negatively with age (p < 0.01). SIJD-affected joints reflect a high mineralization of the sacral inferior region, suggesting increased SIJD-related mechanical stresses. Age-related SCB demineralization is present in all individuals, regardless of dysfunction.

Biochemical Signals Mediate the Crosstalk between Cartilage and Bone in Osteoarthritis

Osteochondral junction is a functional unit comprising the articular cartilage, calcified cartilage, and subchondral bone. Alteration in any component of this composite unit can disrupt the joint integrity and function directly or indirectly. Biochemical signals mediate the crosstalk between tissues and play an essential role in the initiation and progression of osteoarthritis. As osteoarthritis progresses, abnormal subchondral bone remodelling leads to increased angiogenesis and porosity of the subchondral bone plate, which further triggers biochemical signals to mediate the crosstalk between cartilage and bone, contributing to the progression of osteoarthritis. Notably, common biochemical signals include the TGF-β/Smad, Wnt/β-catenin, RANK/RANKL/OPG, and MAPK pathways. This biomarker crosstalk network is the basis of osteoarthritis pathogenesis, and some of their key regulators may be potential therapeutic targets for osteoarthritis drug therapy. This review summarised the biochemical crosstalk between cartilage and bone in the pathogenesis of osteoarthritis, which may provide the basis for the discovery of osteoarthritis treatment targets.

Fixation Technique Using PLLA Pins Gives Good Clinical Results Regardless of Bone Condition in Osteochondral Lesion of Talar Dome

Category: Ankle Introduction/Purpose: Osteochondral lesion of the talus (OLT) has various treatment options which are chosen depending on the stage, size and cartilage condition. The fixation technique can restore the natural congruency with the hyaline cartilage. However, it is not clear whether a bone condition such as the disruption of the subchondral bone plate will affect the clinical results after the fixation of the osteochondral fragment. We hypothesized that even if the subchondral bone plate were disrupted, if the articular cartilage condition in the osteochondral fragment were good, then the clinical results of the fixation technique would be good. The aim of this study was to explore whether the fragment’s bone condition affects clinical outcomes including second look arthroscopy. Methods: Eighteen ankles in 17 patients, which had undergone the fixation technique using poly-L-lactide (PLLA) pins, were included. The mean follow-up period was 18.8±8.9 months. They consisted of 10 males and 7 females, with a mean age of 20.1±10.1 years. Based on the fragment’s bone condition on preoperative CT, ankles were divided into 3 groups; normal, segmentation, and absorption groups. The American Orthopaedic Foot & Ankle Society (AOFAS) score were evaluated both pre and post surgery. On MRI, the BME area was measured, and stability, incorporation, subsidence, and the surface of the articular cartilage of the fragment were evaluated. Second look arthroscopic findings were evaluated in 13 ankles. The repair of OLT was assessed according to the criteria of the ICRS which are allocated for the degree of filling defect by repair tissue, integration, and surface appearance of the repair site. Results: The AOFAS score before surgery significantly improved from 72.1±2.8 points to 98.6±3.3 points at the final follow-up in all ankles. In each group, the AOFAS score improved and there were no significant differences in AOFAS score among the 3 groups at final follow-up. MRI at 1 year showed good incorporation and cartilage surface in all groups, but the bone marrow lesion in the absorption group was significantly larger than that in the other groups. In the second look arthroscopic findings, the ICRS scale for the normal, segmentation, and absorption groups produced 10.6±1.7 points, 9.8±1.9 points, and 10.7±1.2 points, respectively. Conclusion: Good clinical results including those of second look arthroscopy for osteochondral fragment fixation using PLLA pins in OLT were obtained, even in the case of disruption of the subchondral bone plate. Since the fixation procedure can restore the native contour of the articular cartilage surface, this surgical procedure is a viable option for large OLT lesions regardless of bone condition in the osteochondral fragment.

Septic epiphysitis and sequestrum formation in the glenoid of the scapula in a five-month-old foal diagnosed by computed tomography

A five-month-old Connemara foal presented for acute-onset, severe left forelimb lameness with fever, neutrophilia and an elevated serum amyloid A concentration. Radiographs were suspicious of septic physitis of the proximal humerus. CT identified a large defect involving the central portion of the subchondral bone plate of the glenoid and a sequestered bony fragment within the defect, which were not seen radiographically. CT findings were consistent with septic epiphysitis and sequestrum formation, which had significant implications on available treatment options. The foal was given a poor prognosis for returning to soundness so was subject to humane euthanasia.