Influence of intramedullary pressure on Lacuno-Canalicular fluid flow: A systematic review.

While most of current models investigating bone remodelling are based on matrix deformation, intramedullary pressure also plays a role. Bone remodelling is orchestrated by the Lacuno-Canalicular Network (LCN) fluid-flow. The aim of this review was hence to assess the influence of intramedullary pressure on the fluid circulation within the LCN. Three databases (Science Direct, Web of Science, and PubMed) were used. The first phase of the search returned 731 articles, of which 9 respected the inclusion/exclusion criteria and were included. These studies confirm the association between intramedullary pressure and fluid dynamics in the LCN. Among the included studies, 7 experimental studies using animal models and 2 numerical models were found. The studies were then ranked according to the nature of the applied loading, either axial compression or direct cyclic intramedullary pressure. The current review revealed that there is an influence of intramedullary pressure on LCN fluid dynamics and that this influence depends on the magnitude and the frequency of the applied pressure. Two studies confirmed that the influence was effective even without bone matrix deformation. While intramedullary pressure is closely associated with LCN fluid, there is a severe lack of studies on this topic. STATEMENT OF SIGNIFICANCE: Since the 1990's, numerical models developed to investigate fluid flow in bone submicrometric porous network are based on the flow induced by matrix deformation. Bone fluid flow is known to be involved in cells stimulation and hence directly influences bone remodeling. Different studies have shown that intramedullary pressure is also associated with bone mechanosensitive adaptation. This pressure is developed in bone due to blood circulation and is increased during loading or muscle stimulation. The current article reviews the studies investigating the influence of this pressure on bone porous fluid flow. They show that fluid flow is involved by this pressure even without bone matrix deformation. The current review article highlights the severe lack of studies about this mechanism.

[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.

Clinical analysis of distal radius core decompression for chronic wrist pain / 中国修复重建外科杂志

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.

Myogenic autoregulation in bone marrow arterioles and in vivo intramedullary pressure in femora of conscious, female Long Evans rats.

OBJECTIVES: The ability to regulate skeletal blood flow is critical for the maintenance of bone. The myogenic response is essential for regulating tissue blood flow. Myogenic responsiveness in bone marrow arterioles has not yet been determined. Furthermore, the literature is disparate regarding intramedullary pressures (IMP) within bone. The purposes of this study were to (1) determine whether bone marrow arterioles have myogenic activity and (2) assess if the autoregulatory zone corresponds with IMP. Also, this study provides detailed methodology on dissecting and isolating bone marrow arterioles for functional assessment. METHODS: Experiment 1: Femoral shafts of female Long Evans rats were catheterized to assess in vivo IMP. Experiment 2: Bone marrow arterioles from female Long Evans rats were cannulated. Active and passive myogenic responses were determined. RESULTS: In vivo intramedullary pressure averaged 32 ± 3 mmHg, intramedullary pulse pressure averaged 5.28 ± 0.03 mmHg, and the mean maximal diameter and wall thickness of the bone marrow arterioles were 96 ± 7 µm and 18 ± 2 µm, respectively. An active myogenic response was observed and differed (p < .001) from the passive curve. CONCLUSION: Bone marrow arterioles have myogenic responsiveness and the autoregulatory zone corresponded with the range of IMP (15-51 mmHg) within the femoral diaphysis of conscious animals.

Cemented stems in healthy elderly patients result in higher hypoxia despite a paradoxical lower femoral increase of intramedullary pressure.

PURPOSE: Hypoxia is a well-known complication in cemented arthroplasty; however, it is not known whether the level of hypoxia is related to the intramedullary pressure or to the age of the patient; therefore, we studied the intramedullary pressure and level of hypoxia in patients undergoing cemented arthroplasty. METHODS: A prospective study was performed during cemented arthroplasties in 25 patients with an average age of 66.2 ± 12.1 years old. The intramedullary pressure (IMP) was measured by placing a pressure transducer within the bone while simultaneously measuring the pulse oximetry arterial oxygen saturation (SpO2), pulse, and blood pressure. These variables were obtained immediately after spinal anaesthesia, five minutes after cementation, and 15 minutes after prosthesis insertion. RESULTS: One hundred percent of patients had hypoxia at some level, but 83% of elderly patients (older than 66.5 years) had hypoxia (SpO2 <94%) as compared to only 23% of younger patients (p = 0.006). In the group of young patients, IMP was roughly increased 32 times as compared with baseline level, with as consequences a decrease of 4% of SpO2 (from 98.3 to 94.15%); in the elderly group, the IMP was only increased 20 times, but a decrease of 6% of SpO2 (from 97.25 to 91%) was observed. CONCLUSIONS: This series demonstrated higher hypoxia in elderly healthy patients despite a paradoxical lower femoral increase of intramedullary pressure as compared with younger patients. This hypoxia is probably not only related to the cement but also to the patient's age with decline of maximum oxygen uptake capacity and increase bone porosity. CLINICAL TRIALS: ClinicalTrials.gov Identifier: NCT03930537 https://clinicaltrials.gov/ct2/show/NCT03930537.

Advance in Measurement Methods of Intramedullary Pressure after Spinal Cord Injury (review) / 中国康复理论与实践

The measurement of intramedullary pressure is particularly important in the research of spinal cord injury. This article ana-lyzed the influence factors and the measurement methods of intramedullary pressure. The influence factors included edema, vascular regula-tion and bleeding, spinal dural, pia mater spinalis, cerebrospinal fluid, canalis vertebralis and body position, etc. The measurement methods included direct measurement methods, as the sensor placed in the parenchyma of spinal cord, intradural extramedullary or lumbar catheter, and measuring in vitro, and indirect measurement methods, as computer modeling and intraocular pressure measuring.

Longitudinal extension of myelomalacia by intramedullary and subdural hemorrhage in a canine model of spinal cord injury.

BACKGROUND CONTEXT: In canine intervertebral disc (IVD) extrusion, a spontaneous animal model of spinal cord injury, hemorrhage is a consistent finding. In rodent models, hemorrhage might be involved in secondary tissue destruction by biochemical mechanisms. PURPOSE: This study aimed to investigate a causal association between the extents of intramedullary, subdural and epidural hemorrhage and the severity of spinal cord damage following IVD extrusion in dogs. STUDY DESIGN/SETTING: A retrospective study using histologic spinal cord sections from 83 dogs euthanized following IVD extrusion was carried out. METHODS: The degree of hemorrhage (intramedullary, subdural, epidural), the degree of spinal cord damage in the epicenter (white and gray matter), and the longitudinal extent of myelomalacia were graded. Associations between the extent of hemorrhage and the degree of spinal cord damage were evaluated statistically. RESULTS: Intramedullary and subdural hemorrhages were significantly associated with the degree of white (p<.001/ p=.004) and gray (both p<.001) matter damage, and with the longitudinal extension of myelomalacia (p<.001/p=.005). Intriguingly, accumulation of hemorrhagic cord debris inside or dorsal to a distended and ruptured central canal in segments distant to the epicenter of the lesion was observed exhibiting a wave-like pattern on longitudinal assessment. The occurrence of this debris accumulation was associated with high degrees of tissue destruction (all p<.001). CONCLUSIONS: Tissue liquefaction and increased intramedullary pressure associated with hemorrhage are involved in the progression of spinal cord destruction in a canine model of spinal cord injury and ascending or descending myelomalacia. Functional and dynamic studies are needed to investigate this concept further.

Does intramedullary canal irrigation reduce fat emboli? A randomized clinical trial with transesophageal echocardiography.

The effect of medullary cavity irrigation on fat emboli during total knee arthroplasty (TKA) was evaluated. Thirty female patients with osteoarthritis were randomly assigned to undergo conventional TKA without irrigation (conventional group) or with medullary canal saline irrigation (irrigation group). The four-chamber view was monitored by transesophageal echocardiography (TEE) and echogenic reflections of fat emboli were observed. The grey-scale score and area ratio of fat emboli were calculated during TKA. Hemodynamic parameters were simultaneously monitored and showed no obvious change between two groups (P>0.05). The average grey-scale score (P=0.016) and area ratio (P=0.033) of emboli were significantly decreased in irrigation group. Removal of medullary contents by irrigation could significantly reduce the formation of fat emboli during TKA.

Interrelation between external oscillatory muscle coupling amplitude and in vivo intramedullary pressure related bone adaptation.

Interstitial bone fluid flow (IBFF) is suggested as a communication medium that bridges external physical signals and internal cellular activities in the bone, which thus regulates bone remodeling. Intramedullary pressure (ImP) is one main regulatory factor of IBFF and bone adaptation related mechanotransduction. Our group has recently observed that dynamic hydraulic stimulation (DHS), as an external oscillatory muscle coupling, was able to induce local ImP with minimal bone strain as well as to mitigate disuse bone loss. The current study aimed to evaluate the dose dependent relationship between DHS's amplitude, i.e., 15 and 30mmHg, and in vivo ImP induction, as well as this correlation on bone's phenotypic change. Simultaneous measurements of ImP and DHS cuff pressures were obtained from rats under DHS with various magnitudes and a constant frequency of 2Hz. ImP inductions and cuff pressures upon DHS loading showed a positively proportional response over the amplitude sweep. The relationship between ImP and DHS cuff pressure was evaluated and shown to be proportional, in which ImP was raised with increases of DHS cuff pressure amplitudes (R(2)=0.98). A 4-week in vivo experiment using a rat hindlimb suspension model demonstrated that the mitigation effect of DHS on disuse trabecular bone was highly dose dependent and related to DHS's amplitude, where a higher ImP led to a higher bone volume. This study suggested that sufficient physiological DHS is needed to generate ImP. Oscillatory DHS, potentially induces local fluid flow, has shown dose dependence in attenuation of disuse osteopenia.

Dynamic hydraulic fluid stimulation regulated intramedullary pressure.

Physical signals within the bone, i.e. generated from mechanical loading, have the potential to initiate skeletal adaptation. Strong evidence has pointed to bone fluid flow (BFF) as a media between an external load and the bone cells, in which altered velocity and pressure can ultimately initiate the mechanotransduction and the remodeling process within the bone. Load-induced BFF can be altered by factors such as intramedullary pressure (ImP) and/or bone matrix strain, mediating bone adaptation. Previous studies have shown that BFF induced by ImP alone, with minimum bone strain, can initiate bone remodeling. However, identifying induced ImP dynamics and bone strain factor in vivo using a non-invasive method still remains challenging. To apply ImP as a means for alteration of BFF, it was hypothesized that non-invasive dynamic hydraulic stimulation (DHS) can induce local ImP with minimal bone strain to potentially elicit osteogenic adaptive responses via bone-muscle coupling. The goal of this study was to evaluate the immediate effects on local and distant ImP and strain in response to a range of loading frequencies using DHS. Simultaneous femoral and tibial ImP and bone strain values were measured in three 15-month-old female Sprague Dawley rats during DHS loading on the tibia with frequencies of 1Hz to 10Hz. DHS showed noticeable effects on ImP induction in the stimulated tibia in a nonlinear fashion in response to DHS over the range of loading frequencies, where they peaked at 2Hz. DHS at various loading frequencies generated minimal bone strain in the tibiae. Maximal bone strain measured at all loading frequencies was less than 8µÎµ. No detectable induction of ImP or bone strain was observed in the femur. This study suggested that oscillatory DHS may regulate the local fluid dynamics with minimal mechanical strain in the bone, which serves critically in bone adaptation. These results clearly implied DHS's potential as an effective, non-invasive intervention for osteopenia and osteoporosis treatments.

INCREASE OF TIBIAL INTRAMEDULLARY PRESSURE DUE TO MILITARY DRILLING——EXPERIMENTAL AND CLINICAL STUDY / 解放军医学杂志

We found that pain on the medial side of the leg accounted for 6.9% and 19.7% of osteoarticu-lar injuries due to drilling in soldiers in drill, especially those newly recruited. We also found that the pain was produced by an increase in tibial intramedullary pressure. An animal experimentation was done, and the results corroborated our contention. At the same time, we found that decompression of tibial medullary cavity was effective in relieving the symptom.