Intraosseous pressure during loading and with vascular occlusion in an animal model

Transient osteoporosis of the hip in pregnancy

Transient osteoporosis of the hip is an uncommon bone marrow oedema syndrome of unknown pathophysiology affecting previously healthy pregnant women and young to middle-aged men. The disorder is characterised by hip pain, reduced mobility, and the risk of fracture, which is significantly higher in pregnant than in non-pregnant individuals. Diagnosis is by magnetic resonance imaging. Other than a single case-control study, published literature is limited to case series and case reports, with no evidence to guide management, risk of fracture, mode of delivery, safety of breastfeeding and risk of recurrence. An international pregnancy registry may be useful to try to answer some of these questions.

Intraosseous pressure measurement during iliac bone marrow biopsy: its feasibility and difference of IOP in diseased marrow and non-diseased marrow

OBJECTIVE

The purposes of this study were (1) to establish the feasibility and safety of an imaging-guided technique for intraosseous pressure (IOP) measurement in a large cohort of patients, and (2) to compare IOP values between normal and diseased bone marrow.

METHODS

Adult patients undergoing CT-guided marrow biopsy were prospectively and consecutively enrolled from November 2020 to February 2022. IOP measurements were obtained connecting the biopsy needle to a monitoring device using a standard arterial line setup. Clinical data including sex, age and pathology results were obtained. Student t test and Pearson correlation were used for continuous variables comparisons. Univariable analyses were performed using Fisher's exact test. A P value of .05 was considered statistically significant.

RESULTS

A total of 139 participants were initially enrolled, and four were excluded during technique optimization. There were no complications related to the measurement technique. Ninety participants (90/135, 67%) had histology confirming marrow pathology. The participants in the diseased marrow group were older than those in the normal marrow group (63 ± 14 vs. 55 ± 14 years; P < .01). There was no difference in mean IOP between both groups (66 ± 23 vs. 64 ± 28 mmHg; P = .69). There was no correlation between mean arterial blood pressure and mean IOP (P = .08).

CONCLUSION

There was no difference in IOP measurements between patients with normal and diseased marrow undergoing CT-guided biopsy. IOP does not appear to be influenced by systemic blood pressure. No complication occurred during the procedures.

[Clinical analysis of distal radius core decompression for chronic wrist pain]

Objective

To investigate the effectiveness of distal radius core decompression in the treatment of chronic wrist pain caused by various etiologies.

Methods

A retrospective analysis was performed for the clinical data of 10 patients with chronic wrist pain treated with distal radial core decompression between January 2018 and December 2021. There were 6 males and 4 females with an average age of 37.4 years (range, 21-55 years). The disease duration ranged from 7 to 72 months, with an average of 26.5 months. Preoperative MRI examination showed that 10 cases had bone marrow edema at the distal radius on the affected side, and 8 cases had bone marrow edema in the carpal bones such as scaphoid and lunate bone. Among them, 3 patients had a history of wrist fracture, and 2 patients had Kienböck diseases (1 case each in stage ⅡB and stage ⅢA). Three cases were combined with triangular fibrocartilage complex (TFCC) type 1A injury. Two cases were combined with osteoarthritis, 1 of them was complicated with severe traumatic arthritis, the wrist arthroscopy showed that the TFCC was completely lost and could not be repaired, and the cartilage of the lunate bone and the ulnar head were severely worn.Visual analogue scale (VAS) score was used to evaluate the relief of wrist pain before operation, at 6 months after operation, and at last follow-up, and the range of motion of the affected wrist in dorsiflexion, palmar flexion, ulnar deviation, and radial deviation was measured. The degree of bone marrow edema was evaluated according to T1WI, T2WI, and STIR sequences of MRI.

Results

All the patients were followed up 12-22 months, with an average of 16.4 months. Except for 1 patient who experienced persistent wrist joint pain and limited mobility after operation, the remaining 9 patients showed significant improvement in pain symptoms and wrist joint mobility. The VAS score and range of motion of wrist dorsiflexion, palmar flexion, ulnar deviation, and radial deviation at 6 months after operation and at last follow-up were significantly improved when compared with those before operation, the VAS score and the range of motion of wrist ulnar deviation and radial deviation at last follow-up were further improved when compared with those at 6 months after operation, all showing significant differences ( P<0.05). There was no significant difference in wrist dorsiflexion and palmar flexion between at 6 months after operation and at last follow-up ( P>0.05). Bone marrow edema was improved in 6 patients on MRI at 6 months after operation, and was also improved in other patients at last follow-up.

Conclusion

For chronic wrist pain caused by a variety of causes, distal radius core decompression can directly reduce the pressure of the medullary cavity of the distal radius, improve the blood supply of the corresponding distal structure, significantly alleviate chronic wrist pain, and provide an option for clinical treatment.

Combined computational analysis and cytology show limited depth osteogenic effect on bone defects in negative pressure wound therapy

Background: The treatment of bone defects remains a clinical challenge. The effect of negative pressure wound therapy (NPWT) on osteogenesis in bone defects has been recognized; however, bone marrow fluid dynamics under negative pressure (NP) remain unknown. In this study, we aimed to examine the marrow fluid mechanics within trabeculae by computational fluid dynamics (CFD), and to verify osteogenic gene expression, osteogenic differentiation to investigate the osteogenic depth under NP. Methods: The human femoral head is scanned using micro-CT to segment the volume of interest (VOI) trabeculae. The VOI trabeculae CFD model simulating the bone marrow cavity is developed by combining the Hypermesh and ANSYS software. The effect of trabecular anisotropy is investigated, and bone regeneration effects are simulated under NP scales of -80, -120, -160, and -200 mmHg. The working distance (WD) is proposed to describe the suction depth of the NP. Finally, gene sequence analysis, cytological experiments including bone mesenchymal stem cells (BMSCs) proliferation and osteogenic differentiation are conducted after the BMSCs are cultured under the same NP scale. Results: The pressure, shear stress on trabeculae, and marrow fluid velocity decrease exponentially with an increase in WD. The hydromechanics of fluid at any WD inside the marrow cavity can be theoretically quantified. The NP scale significantly affects the fluid properties, especially those fluid close to the NP source; however, the effect of the NP scale become marginal as WD deepens. Anisotropy of trabecular structure coupled with the anisotropic hydrodynamic behavior of bone marrow; An NP of -120 mmHg demonstrates the majority of bone formation-related genes, as well as the most effective proliferation and osteogenic differentiation of BMSCs compared to the other NP scales. Conclusion: An NP of -120 mmHg may have the optimal activated ability to promote osteogenesis, but the effective WD may be limited to a certain depth. These findings help improve the understanding of fluid mechanisms behind NPWT in treating bone defects.

Load-deformation characteristics of cadaver patellae: Relationship to intraosseous pressure

BACKGROUND

Anterior knee pain can arise from several sources. One of the main sources of pain in patients with anterior knee pain is the patella. Increased patellofemoral joint loading is the prime source of patellar pain. Elevated intraosseous pressures have been measured in painful patellae and increasing the intraosseous fluid pressure in the patella causes pain. Whether elevated fluid pressure is an independent source of pain or if the patellar deformation under load leads to elevated pressure and pain has not been determined. Our hypothesis was that the patella deforms measurably under physiologic loads and that intraosseous pressure increase is related to that deformation. The relationship may be linear as measured by correlation or nonlinear as measured by the sum of squared error.

METHODS

Part I: Assessment of patellar load-deformation profiles were obtained in 2 intact cadaver patellae and 1 bisected patella under physiologic loads. Part II: Measurements of intraosseous pressure were obtained in 9 cadaver patellae as the patellae were compressed with physiologic loads. Pressures were recorded at sequential levels of anterior-posterior patellar compression.

FINDINGS

Cadaver patellae compress up to 3.5 mm in the anterior-posterior plane. Compression with physiologic forces raises intraosseous pressure to more than 40 mmHg.

INTERPRETATION

Load-deformation of cadaver patellae results in deformation and an increase in intraosseous pressure. These findings may help explain previous studies of patellofemoral pain where elevated patellar intraosseous pressures have been found in vivo.

Changes in bone density, intraosseous pressure of distal femoral articular cartilage and subchondral bone after proximal femoral medullary cavity cement filling in rabbits

Bone cement is widely used, particularly in hip replacements, but the potential clinical complications of its use have been largely unrecognized. The purpose of the present study was to investigate the effects of bone cement in the proximal femoral medullary cavity (PFMC) on bone mineral density (BMD), intraosseous pressure (IOP), articular cartilage and subchondral bone in the distal femurs of rabbits. A total of 32 New Zealand white rabbits were randomly numbered and the left hind limb of the odd-numbered rabbits and the right hind limb of the even numbered rabbits were selected as the experimental side. For each rabbit, the non-experimental hind limb was labeled as the control side by the principal investigator. An intramedullary injection of polymethyl methacrylate was made into the experimental hindlimb of each rabbit and the PFMC filled with bone cement. BMD and IOP of the distal femur of the bilateral hindlimb were measured at 4 and 16 weeks after surgery, and histological and ultra-fine structural features were examined by light and transmission electron microscopy, respectively. At week 4 after the operation, IOP in the experimental limb was significantly higher and BMD lower compared with the control limb. At the 16th week after operation, the IOP in the experimental limb was lower than at the 4th week after operation, but still higher compared with controls, and the BMD was significantly higher than the controls. In the controls, IOP and BMD was not significantly different between the 4th and 16th week after operation. Compared with controls, the cartilage in the experimental group was thinner, the chondrocytes partially necrotic and the trabecular structure of the subchondral bone broken. Analysis of ultra-fine structural features in the experimental group showed chondrocytes with necrotic cytoplasm and pyknotic nuclei relative to controls. The results indicated that blockage of the PFMC with bone cement resulted in an increase in the IOP in the distal femur, a change in BMD and damage to the subchondral bone and articular cartilage.

Subchondral pressures and perfusion during weight bearing

Background

Joints withstand huge forces, but little is known about subchondral pressures and perfusion during loading. We developed an in vitro calf foot model to explore intraosseous pressure (IOP) and subchondral perfusion during weight bearing.

Methods

Freshly culled calf forefeet were perfused with serum. IOP was measured at three sites in the foot using intraosseous needles, pressure transducers, and digital recorders. IOP was measured during perfusion, with and without a tourniquet and with differing weights, including static loading and dynamic loading to resemble walking.

Results

IOP varied with perfusion pressure. Static loading increased subchondral IOP whether the bone was non-perfused, perfused, or perfused with a proximal venous tourniquet (p < 0.0001). Under all perfusion states, IOP was proportional to the load (R² = 0.984). Subchondral IOP often exceeded perfusion pressure. On removal of a load, IOP fell to below the pre-load value. Repetitive loading led to a falling IOP whether the foot was perfused or not.

Conclusion

Superimposed on a variable background IOP, increased perfusion and physiological loading caused a significant increase in subchondral IOP. Force was thereby transmitted through subchondral bone partly by hydraulic pressure. A falling IOP with repeat loading suggests that there is an intraosseous one-way valve. This offers a new understanding of subchondral perfusion physiology.