Changes In Intra-articular Pressure Research Articles

Radiocapitellar and Ulnotrochlear Pressures Increase in a Radial Head Fracture Model: A Cadaveric Biomechanical Analysis.

Changes in intra-articular pressure have not been previously described in relation to the management of radial head fractures. We hypothesized that pressure within the radiocapitellar and ulnotrochlear joints would increase with progressive radial head resection, mimicking a displaced radial head fracture, in a cadaveric model. Ten cadaveric specimens were tested. Intra-articular pressure sensors were used to measure pressure within the radiocapitellar and ulnotrochlear joints with the forearm in full supination. The elbow was loaded to 100 N in extension, 45° of flexion, and 90° of flexion under the following conditions: (1) intact radial head, (2) 20% radial head resection, (3) 40% radial head resection, and (4) 100% radial head resection. The distribution of pressure between the radiocapitellar and ulnotrochlear joints did not change with sequential, partial resection of the radial head (radiocapitellar joint, between 48.92% and 53.79%; ulnotrochlear joint, between 46.21% and 51.08%). After 20% resection, radiocapitellar peak contact pressure (PCP) increased by 22% (from 1,410 to 1,721.5 kPa) and ulnotrochlear PCP increased by 36% (from 1,319 to 1,797.5 kPa). After 40% resection, radiocapitellar PCP increased by 123% (from 1,410 to 3,145 kPa; p = 0.0003) and ulnotrochlear PCP increased by 105% (from 1,319 to 2,702 kPa; p = 0.007). Ulnotrochlear PCP increased by a total of 159% after complete radial head resection (from 1,319 to 3,415.5 kPa; p = 0.003). Pressures in the radiocapitellar and ulnotrochlear joints were equally distributed with an intact radial head and after partial resection. Radiocapitellar and ulnotrochlear pressures increased with increasing radial head resection, significantly exceeding 100% of normal after radial head resection of 40% of the anterolateral diameter. Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Intra-articular Pressure Changes during Stifle Arthroscopy Using a Cadaver Model

Abstract Objective The aim of the study was to measure canine stifle intra-articular pressures (IAP) during arthroscopy using three different fluid pump pressure (FPP) settings. Study Design Frozen thawed canine cadavers were used. The stifle was distended using a 2.7 mm arthroscope connected to a commercial fluid pump. Intra-articular pressure was measured using a portable pressure gauge connected to an intra-articular 18 G needle. Intra-articular pressure was recorded during stifle extension, 90 degrees flexion and full flexion at three different FPP (30, 50, 80 mm Hg). Results Testing was performed on 27 stifles. Intra-articular pressure significantly increased at higher FPP (p < 0.01). At FPP 30, 50, and 80 mm Hg, the mean IAP was 51.8 (95% confidence interval [CI]: 41.3–62.2), 103.3 (95% CI: 92.8–113.7), and 175.2 mm Hg (95% CI: 164.8–185.6), respectively. At FPP 30 and 50 mm Hg, IAP always remained under 170 mm Hg. At 80 mm Hg, IAP raised to or above 170 mm Hg in 11/14 stifles. Stifle position significantly affected IAP (p < 0.01). Changing stifle position from 90 degrees flexion to extension significantly decreased IAP by 22.4 mm Hg (95% CI: 16.2–28.5), and changing to full flexion significantly increased IAP by 20.9 mm Hg (95% CI: 14.8–27.1; p < 0.01). Conclusion Our results suggest that caution should be used during stifle arthroscopy to limit risk for iatrogenic capsular damage. Fluid pump pressure 30 mm Hg is considered safe when using a 2.7 mm arthroscope and high flow cannula. If higher FPP is necessary for visualization, duration of stifle flexion should be limited. Fluid pump pressure 80 mm Hg should be avoided.

Changes in intraarticular pressure on the blood supply in the retinaculum of the femoral neck

BackgroundThis study aimed to analyze the effects of intracapsular pressure (IAP) on blood flow in the femur after a femoral neck fracture. MethodsFour simplified vascular models were used to measure the effect of vessel length on arterial blood flow in 10 New Zealand white rabbits. Ten models were evaluated under 10 different blood pressures. FindingsIAP increased following fracture of the femoral neck, and deformation had the greatest potential effect on blood flow in the retinacular artery. When blood pressure was fixed at 60 mm Hg, an increase in IAP caused a reduction in blood flow. When the IAP was relatively high (above 60 mm Hg), and higher than the blood pressure, blood flow continued to drop as intracapsular pressure increased. Shortening of blood vessels had no significant effect on blood supply. However, the p-value was uniformly significant (<0.05) when stretched and twisted blood vessels were compared with normal blood vessels. InterpretationThe results of computational fluid-structure interaction similarly indicated that a smaller blood vessel diameter and twisted blood vessels will result in decreased flow velocity when IAP increases. This study also revealed a close relationship between IAP and the hip joint's position and traction.

The Effect of Orthotics on Ankle and Subtalar Joint Orientation and Load Distribution Utilizing a Novel System to Simulate Weight Bearing in a Cadaveric Model

Category: Ankle, Basic Sciences/Biologics, Hindfoot, Biomechanics Introduction/Purpose: Orthotics are commonly prescribed by orthopaedic surgeons to address the hindfoot and midfoot deformity resulting from posterior tibial tendon dysfunction. The public however will often purchase over the counter orthotics for generalized complaints of foot pain that is not associated with any significant deformity or foot pathology. The mechanical axis of the lower limb may be altered in patients who use orthotics despite a normal foot alignment. We hypothesize that patients with normal alignment who use orthotics may adversely change ankle and subtalar joint orientation and load distribution. Methods: Five fresh frozen lower limb cadaveric specimens without known skeletal condition were used. The femoral head was potted with PMMA and TekScan pressure sensors were inserted into the ankle and subtalar joint. The specimens were placed on a custom jig, which allowed for load cell modulated loading of the leg; 75 lb load (half body weight) was applied at the femoral head while the foot was supported against a fixed plate keeping the ankle in neutral position. Testing was achieved by placing an orthotic under the medial half of the plantar talonavicular joint level. Mean pressure (MP), peak pressure (PP), contact area (CA), and center of force (COF) were measured in both the ankle and subtalar joints under three conditions; barefoot (BASE), with a 1.5 cm (ORT1) and 3 cm (ORT2) height orthotic. Each condition was tested three times per specimen. Displacement of COF was calculated relative to its location at baseline. Results: The MP, PP and CA showed a constant decrease from BASE to ORT1 and ORT2. Despite this relation, the only comparison that was significantly different was that between peak pressure values of the baseline and ORT2 conditions of the subtalar joint. The average displacement of COF from BASE was 0.14 mm and 0.42 mm medially, and 0.26 mm and 0.46 mm posteriorly at the ankle joint with ORT1 and ORT2 respectively. The average displacement of COF from BASE was 0.03 mm laterally and 0.08 mm posteriorly with ORT1, and 0.2 mm medially and 0.46 mm posteriorly with ORT2 at the subtalar joint. Conclusion: Foot deformities have an impact on the articular forces in the lower limb. Our results agree with previous studies about the role of foot deformity on the distribution of body weight forces and its consequences across the ankle and subtalar joint. Our novel study also demonstrates that orthotics and orthotics of varying sizes can change the mean pressure, peak pressure, contact area center of force in the ankle and subtalar joint. This study proves the feasibility of its design for studying intra-articular pressure changes in a lower limb cadaveric model with simulated weight bearing.

Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology

The objective of this article is to summarize current understanding of biomechanical factors that cause ulnar drift in the hands of patients with rheumatoid arthritis. This was done through literature review of published articles on the mechanical etiology of ulnar drift. There are several theories regarding the cause of ulnar drift, however conclusive evidence is still lacking. Current mechanical factors that are postulated to play a role include: failure of the collateral ligaments, intra-articular pressure changes, degenerative changes in the carpal and metacarpal anatomy, muscle hypoxia induced changes in wrist tension, and exacerbating activities of daily living. Although current theories regarding ulnar drift almost universally include an at least partially mechanical rationale, the causes may be multifactorial. Significantly more research is needed to elucidate the relative importance of mechanical factors leading to significant ulnar drift concurrent with advanced rheumatoid arthritis.

Temporomandibular joint arthrocentesis. Review of the literature

The treatment of the temporomandibular joint (TMJ) is still controversial. TMJ arthrocentesis represents a form of minimally invasive surgical treatment in patients suffering from internal derangement of the TMJ, especially closed lock. It consists of washing the joint with the possibility of depositing a drug or other therapeutic substance. Resolution of symptoms is due to the removal of chemical inflammatory mediators and changes in intra-articular pressure. Numerous clinical studies regarding this technique have been published. The goal of this paper is to review all clinical articles that have been published with regard to the critique of this technique. 19 articles with different designs fulfilling selection guidelines were chosen. A series of clinical and procedure variables were analyzed. Although the mean of improvement was higher that 80%, further research is needed to determine more homogeneous indications for TMJ athrocentesis. Key words:Temporomandibular joint, arthrocentesis, minimally invasive surgery.

Fluoroscopically Guided Hip Capsulotomy: Effective or Not? A Cadaveric Study

The purpose of this study was to examine the efficacy of a fluoroscopically guided hip capsulotomy. Ten fresh-frozen paired cadaveric hips were injected under fluoroscopic guidance with saline sufficient to generate an intra-articular pressure greater than 58 mmHg. The pressure was monitored continuously using a percutaneous transducer. A limited lateral approach to the proximal femur was performed by one of two senior orthopaedic trauma surgeons. Using a scalpel under fluoroscopic guidance, each surgeon made one attempt at an anterior capsulotomy. Changes in intra-articular pressure were recorded throughout the procedure. The specimens were then dissected to measure the extent of each capsulotomy as well as the distance from the capsulotomy to nearby neurovascular structures. A rapid and substantial decrease in intra-articular pressure was seen in all hips. The mean intra-articular pressure postcapsulotomy was 8.4 mmHg. The capsulotomies averaged 15.1 mm in length. None of the attempts at capsulotomy lasted longer than 90 seconds. The average distance between capsulotomy and the lateral-most branch of the femoral nerve was 19.5 mm. The femoral artery was on average 40.3 mm from the capsulotomy. There was no correlation between the side on which capsulotomy was performed and its extent or proximity to neurovascular structures. Fluoroscopically guided hip capsulotomy through a small lateral incision appears to be a safe, effective, and expedient method, which may substantially reduce intra-articular pressure after minimally displaced femoral neck fractures.

Changes in intra-articular pressure of the TMJ during mastication of steamed rice

Changes in intra-articular pressure of the TMJ during mastication of steamed rice

加圧関節洗浄療法における顎関節内圧の測定

To investigate the effect of distension and removal of adhesion in the upper joint space after lavage under sufficient hydraulic pressure during arthrocentesis, we measured changes in intra-articular pressure in the joint space and performed arthroscopic examinations during the procedure.Eight patients (8 joints) with closed lock of the temporomandibular joint who underwent arthrocentesis and arthroscopic examination were studied. Adhesion was observed in 5 joints on arthroscopic examination before irrigation; the remaining 3 joints had no adhesion. Changes in intra-articular pressure during irrigation under high pressure (40KPa) were measured in these 8 joints. In 5 joints with adhesion, arthroscopic examination was repeated to confirm whether the adhesion was removed after irrigation.Immediately after application of pressure, the intra-articular pressure in the joints without adhesion was 9.1-14.7 KPa, and that in the joints with adhesion was 10.0-13.3 KPa. After applying pressure to the joints without adhesion, 30 seconds were required until a stable pressure was reached, whereas 2 to 5minutes were required in joints with adhesion. In all 5 joints with adhesion, removal of the adhesion was observed on arthroscopic examination after the intra-articular pressure decreased to a stable level.These results indicate that lavage under sufficient hydraulic pressure, which is a 2-to 5-minute procedure, can widen a narrowed joint space and remove adhesion.

Intra-articular pressure changes in rheumatoid and normal peripheral joints.

To investigate the intraarticular pressure (IAP) dynamics of a spectrum of joints in rheumatoid and normal subjects in order to determine whether a reperfusion event is likely to occur at these sites. IAP was measured in the metacarpophalangeal (MCP) (n = 8), wrist (n = 8), ankle (n = 4), and elbow joints (n = 4) of rheumatoid subjects, in addition to the MCP (n = 8), wrist (n = 6), and ankle joints (n = 1) of normal healthy controls, using the hand held portable 295-1 Intra-Compartmental Pressure Monitor System (Stryker, UK). Resting IAP was positive in all rheumatoid joints, and subatmospheric or weakly atmospheric in normal subjects (p < 0.01). Exercise produced an increase in IAP in rheumatoid subjects only (p < 0.01). The addition of saline to normal joints mimicked the IAP changes seen in the rheumatoid group. These observations suggest that increased resting IAP is a marker for chronic joint inflammation. The IAP increase seen in the rheumatoid group during exercise supports the concept of hypoxic reperfusion mediated joint injury.

Dynamic analysis of intraarticular pressure in the glenohumeral joint

Dynamic analysis of intraarticular pressure was performed in 180 glenohumeral joints. The intraarticular pressure demonstrated characteristic changes during shoulder movement. In the healthy group minimum pressure was measured at 40 degrees of elevation in the scapular plane. In patients with contractures the pressure increased in the early phase of elevation and persisted. Pressure changes of the group with incomplete tears of the rotator cuff resembled those of the healthy group, whereas those in the massive tear group showed only slight pressure changes. When patients with rotator cuff tears had no limitation of arm elevation, pressure changes close to the normal pattern were found. However, when active elevation was markedly limited, no significant pressure changes were noted in some cases. In unstable shoulders the rate of pressure increase was slower, and the range of pressure changes was more limited than that in the healthy group. It is speculated that changes in intraarticular pressure reflect the intraarticular volume. Measurement of the intraarticular pressure may be clinically useful in functional assessment.

Intraarticular pressure of the shoulder

Nine fresh frozen cadaveric shoulders were used to examine the changes in intraarticular pressure (IAP) of the shoulder joint and the position of the humeral head under various loads to determine the relationship between these parameters. All the soft tissues superficial to the rotator cuff were removed. The position of the humerus relative to the scapula was monitored using an electromagnetic tracking system before and after venting the capsule with 0, 0.5, and 1.0 kg of load applied to the humerus inferiorly in addition to the weight of the arm. Simultaneously, the IAP was monitored using a pressure transducer before venting the capsule. Venting had a significant effect on the position of the humeral head: the positions of the head after venting were significantly lowered in all loading conditions. The average IAP was -76 cm H2O without load, and the value decreased in a linear fashion with increased load; the correlations were significant in four of six shoulders without dislocation. The correlations were less significant between the pressure and the position, and there were no significant correlations between the load and the position. IAP, which is determined primarily by the load applied, is important to stabilize the shoulder inferiorly. Because IAP is intimately related to the external load and the response is specific to individuals, examination of IAP response to external load may be helpful in characterizing various instabilities of the shoulder.

Intraarticular pressure during continuous passive motion of the human knee.

Intraarticular pressure (IAP) was continuously monitored during continuous passive motion (CPM) of five normal and 11 abnormal human knees using a new fiberoptic, transducer-tipped Camino catheter. IAP varied in a consistent hysteresis pattern in the normal knees, with subatmospheric pressures recorded at intermediate angles of joint flexion. A similar pattern was recorded in the abnormal knees without cruciate ligament pathology, whereas considerable variability was noted in the knees with cruciate ligament abnormality. IAP was lower in the extension to flexion than in the flexion to extension portion of the CPM cycle, providing evidence of intraarticular fluid flow during portions of the CPM cycle. IAP changes were consistent with "physiologic compartmentation" within the knee at extremes of joint position. Capsular viscoelastic changes and/or synovial fluid volume changes were observed during CPM. The therapeutic mechanism of continuous passive motion may be related to cyclic variation of the intraarticular pressure.

Fluid compartmentation and articular mechanoreceptor discharge in the cat knee joint.

Experiments were performed to determine the effect of alteration of intra-articular pressure in different areas of the cat knee joint on the discharge of slowly adapting mechanoreceptors in the posterior region of the joint. At physiological (subatmospheric) pressures the anterior and posterior regions of the knee joint are not hydraulically continuous. However, at supra-atmospheric pressures between 2.5 and 9 cmH2O there is free communication between these areas. The discharge of receptors in the posterior region of the joint is influenced by intra-articular pressure changes in the posterior region when these are supra-atmospheric. However, pressure changes in the anterior region of the joint have little effect on the discharge of these receptors until free communication occurs between anterior and posterior regions. It is suggested that articular mechanoreceptors detect tension changes in collagen fibrils rather than volume changes of the joint capsule.