Intra-articular Pressure Research Articles

The effect of negative intraarticular pressure and rotator cuff force on Glenohumeral translation during simulated active elevation

Objective: The objective of this study was to determine the effect of negative pressure in the intraarticular space and subacromial bursa, as well as rotator cuff force, on glenohumeral translation during active elevation. Design: Glenohumeral translation during elevation in the scapular plane was measured under greater than, less than, and equal to physiologic rotator cuff muscle force, as well as with and without the subacromial bursa and intraarticular space vented. Background: Negative intraarticular pressure has been shown to help stabilize the glenohumeral joint in passive motion, although the effect on translation during active motion has not been investigated. Methods: Eight cadaverous human shoulder specimens were tested in a dynamic shoulder simulator. Forces in the muscles of the rotator as well as the middle deltoid muscle were simulated using servohydraulic cylinders. Joint motion was measured using an ultrasonic motion analysis system. Results: Superior translation of the humerus increased 1.2 mm (SD, 0.4) upon venting of the bursa, and 2.1 mm (SD, 1.7) upon venting of the joint capsule at 25° of glenohumeral elevation in the scapular plane. At 90° elevation, venting the bursa did not change superior translation but increased anterior translation 1.04 mm (SD, 1.0). Venting of the joint capsule increased superior translation by 2.8 mm (SD, 2.5). Decreasing rotator cuff force increased superior translation, while reducing it did not. Conclusion: The muscles of the rotator cuff and the negative pressure of the intraarticular space and the subacromial bursa stabilize the glenohumeral joint since they restrict translation in the superior and anterior directions. Relevance Increased glenohumeral translation and the resulting asymmetric loading may lead to arthrosis and ultimately rotator cuff arthropathy.

Joint distraction in treatment of osteoarthritis (II): effects on cartilage in a canine model

Objective From a clinical point of view, joint distraction as a treatment for osteoarthritis (OA) of hip and ankle has been demonstrated to be very promising. Pain, joint mobility and functional ability, the most important factors for a patient with severe OA, all improved. Although radiographic joint space enlargement in a significant number of patients suggested cartilage repair, actual cartilage repair remains difficult to evaluate. Therefore the present study was initiated to evaluate the actual effects of joint distraction on cartilage.Methods For this purpose a canine model for OA, anterior cruciate ligament transection (ACLT) was used. Sixteen weeks after ACLT articulating Ilizarov joint distraction of the knee was carried out. Absence of mechanical contact between articular surfaces and presence of intra-articular intermittent fluid pressure, characteristics of Ilizarov joint distraction, were confirmed. Twenty-five weeks after ACLT joint tissue of the dogs was analyzed.Results Biochemical analysis showed that after joint distraction the abnormal cartilage proteoglycan (PG) metabolism, characteristic for OA, had changed to a level found in control joints. Moreover, a mild degree of inflammation, present after ACLT, was reduced upon joint distraction. PG-content and histological cartilage degeneration had not (yet) improved within the time of treatment.Discussion Results suggest that the promising clinical results of Ilizarov joint distraction in patients with OA are accompanied by changes in cartilage metabolism. A change in proteoglycan turnover, indicating normalization of overall chondrocyte function, might in the long term, with normal joint use, lead to actual repair of cartilage.{copy}

Clinical study of the pumping pressure changes in the temporomandibular joint space before and after arthroscopic surgery.

When arthroscopy of the temporomandibular joint (TMJ) is performed, we often observe differences in the resistance of hydraulic pressure during intra-articular pumping. It can be speculated that intra-articular adhesion and contracture of the capsule and ligament may cause these differences in resistance. In order to measure the changes in intra-articular hydraulic pressure before and after arthroscopic ablation surgery, seven cases were examined by balloon pumping technique. We concluded that the values of intra-articular hydraulic pressure are implicated in the severity of the internal derangement of TMJ.

Effect of joint compression on inferior stability of the glenohumeral joint

To determine the relative importance of negative intraarticular pressure, capsular tension, and joint compression on inferior stability of the glenohumeral joint we studied 17 fresh, normal adult cadaver shoulders using a “3 degrees of freedom” shoulder test apparatus. Translations were measured in intact and vented shoulders while a 50-N superior and inferior directed force was applied to the shoulder. Three different joint compressive loads (22 N, 111 N, 222 N) were applied externally. Tests were performed in 3 positions of humeral abduction in the scapular plane (0°, 45°, 90°) and in 3 positions of rotation (neutral, maximal internal, and maximal external). After tests of the intact and vented shoulder, the glenohumeral ligaments were sectioned and tests were repeated. With minimal joint compression of 22 N, negative intraarticular pressure and capsular tension limited translation of the humeral head on the glenoid. Increasing the joint compressive load to 111 N resulted in a reduction of mean inferior translation from 11.0 mm to 2.0 mm at 0° abduction, from 21.5 mm to 1.4 mm at 45° abduction, and from 4.5 mm to 1.2 mm at 90° abduction. With a compressive load of 111 N, venting the capsule or sectioning of glenohumeral ligaments had no effect on inferior stability. Clinical relevance: Glenohumeral joint compression through muscle contraction provides stability against inferior translation of the humeral head, and this effect is more important than negative intraarticular pressure or ligament tension.

Starving the synovium: angiogenesis and inflammation in rheumatoid arthritis.

Starving the synovium: angiogenesis and inflammation in rheumatoid arthritis.

Characterization of the effect of high molecular weight hyaluronan on trans-synovial flow in rabbit knees.

1. The effect of a rooster comb hyaluronan (3.6-4.0 g l-1) of similar chain length to rabbit synovial fluid hyaluronan, on the trans-synovial escape of fluid from the joint cavity in the steady state ( 8d s) was studied in 29 rabbit knees at controlled intra-articular pressures (Pj). 2. Rooster hyaluronan caused the pressure-flow relation to flatten out as pressure was raised. At 10-20 cmH2O the slope of the quasi-plateau, 0.05 +/- 0.01 microliter min-1 cmH2O-1 (mean +/- s.e.m.), was 1/39th that for Ringer solution (1.94 +/- 0.01 microliter 2O-1 ). 3. Bovine synovial fluid had a similar effect to hyaluronan in Ringer solution. 4. The quasi-plateau was caused by increasing opposition to outflow; the pressure required to drive unit outflow increased 4.4-fold between 5 and 20 cmH2O. The increased opposition to outflow at 20 cmH2O was equivalent to an effective osmotic pressure of 13-17 cmH2O at the interface. Since the infusate's osmotic pressure was only 0.9 cmH2O, this implied concentration polarization to 15-18 g l-1 hyaluronan at the interface. 5. Mechanical perforation of the lining, or enzymatic degradation of the interstitial matrix by chymopapain, abolished the quasi-plateau. Hydrational expansion of the matrix by approximately 2-fold did not. The increased opposition to outflow was reversible by washing out the hyaluronan, or by reducing Pj. It was unaffected by interruption of tissue blood flow or synoviocyte oxidative metabolism. These properties are compatible with a concentration polarization mechanism, i.e. flow-induced concentration of hyaluronan at the synovial interface due to molecular reflection. 6. A concentration polarization theory was developed for a partially reflected solute. Numerical solutions supported the feasibility of this osmotic explanation of the quasi-plateau. Additional mechanisms may also be involved. 7. It is concluded that native-size hyaluronan helps to retain synovial fluid in the joint cavity when pressure is raised and acts, at least in part, by exerting osmotic pressure at the interface between synovial matrix and a concentration polarization layer.

Intra-articular pressure, elastance and range of motion in healthy and injured racehorse metacarpophalangeal joints.

The objective of this study was to determine if intraarticular pressure, elastance of the soft tissue forming the dorsal pouch, and range of motion in flexion measurements are significantly different in Thoroughbred metacarpophalangeal joints with clinical evidence of idiopathic synovitis, primary synovitis, synovitis/capsulitis, or osteoarthritis relative to clinically normal joints. Forty-two metacarpophalangeal joints, in 25 active or retired Thoroughbred racehorses, were categorised by palpation and visual inspection of the palmar pouch into one of 4 increasing grades of distention. Intra-articular pressures were then measured using 2 pressure transducers attached to 22-gauge needles from both the dorsal and palmar pouches simultaneously while the horses stood squarely under mild sedation. After obtaining baseline pressure measurements, a third needle was inserted into the dorsal pouch, and 0.5 ml increments of saline solution were added every 10 s to perform a pressure/volume (elastance) study of the dorsal pouch. The elastance study for each joint ended when leakage into the palmar pouch was detected by the pressure transducer placed in that region. A lateral radiographic view was taken of each metacarpophalangeal joint in maximal flexion. The maximum angle of flexion was measured from the radiograph, and this angle was subtracted from 180 degrees to acquire the range of motion in flexion. In this study, all Thoroughbreds with clinical evidence of lameness and/or sensitivity to flexion, referable to the metacarpophalangeal joint region, had fluid distention of the palmar pouch (grade 2 or 3 distention). The 16 metacarpophalangeal joints with no clinical abnormalities had a mean palmar pouch pressure of -1.25 mmHg. Joints afflicted with synovitis/capsulitis had the highest intraarticular pressures (mean +51.00 mmHg); however, joints with idiopathic synovitis (mean +15.71 mmHg), primary synovitis (mean +28.33 mmHg) and osteoarthritis (mean +26.20 mmHg) also had significantly elevated intraarticular pressures relative to the clinically normal group. Thoroughbred metacarpophalangeal joints diagnosed with synovitis/capsulitis, or osteoarthritis, had significantly increased elastance (stiffness) of the soft tissue forming the dorsal pouch relative to the normal group and, probably, as a result significantly decreased range of motion in flexion. The presence of primary synovitis alone did not have a significant immediate effect on elastance of the dorsal pouch and range of motion in flexion. The 16 Thoroughbred metacarpophalangeal joints assessed as having no clinical abnormalities had a mean range of motion in flexion of 60.81 degrees. The mean range of motion in flexion of Thoroughbred metacarpophalangeal joints with a clinical diagnosis of primary synovitis was 53.67 degrees; idiopathic synovitis 52.14 degrees; synovitis/capsulitis 44.20 degrees; and those with radiographic evidence of moderate to marked osteoarthritis 30.80 degrees. This study demonstrated that, as the severity of the clinical evidence of metacarpophalangeal joint injury/disease increased, the range of motion in flexion decreased.

Local hemodynamics, permeability, and oxygen metabolism during acute inflammation of innervated or denervated isolated equine joints

Abstract Objectives To determine oxygen metabolism, permeability, and blood flow in isolated joints in response to interleukin 1β (IL-1β) and contribution of innervation. Sample Population One metacarpophalangeal (MCP) joint of 24 adult horses. Procedure The MCP joint was isolated for 6 hours in a pump-perfused, auto-oxygenated, innervated or denervated preparation. Isolated joints were assigned to the following 4 groups: control, control-denervated, inflamed, and inflamed-denervated, and inflammation was induced by intra-articular injection of IL-1β. Circuit arterial and venous pressures, flows, and blood gas tensions, synovial fluid production, and intra-articular pressure were measured. Total vascular resistance; oxygen delivery, consumption, and extraction ratio (ER); and permeability surface area product were calculated. Synovial membrane blood flow was determined at 0, 60, and 330 minutes. Synovial membrane wet-to-dry ratio was obtained, and permeability to macromolecules was determined by intra-articular injection of Evans blue albumin and fluorescein isothiocyanate-conjugated dextran. Results Oxygen delivery and synovial membrane blood flow progressively increased but were not different among groups. Oxygen consumption and ER significantly increased in inflamed joints, as did intraarticular pressure and synovial fluid production. Inflamed joints had greater wet-to-dry ratio. Albumin permeability significantly increased in the villous synovial membrane of the inflamed groups, and dextran permeability was increased in the innervated groups, with a trend toward increased permeability in inflamed groups. Conclusion Inflammation significantly increased oxygen demand, which was initially met by increased ER. Permeability to small molecules was increased with inflammation; innervation increased permeability to large molecules. Use of an isolated joint model enabled documentation of the physiologic responses of the joint to acute inflammation. (Am J Vet Res 1998;59:1307–1316)

Effect of depletion of glycosaminoglycans and non-collagenous proteins on interstitial hydraulic permeability in rabbit synovium.

1. The hydraulic resistance of synovial interstitium helps to retain a lubricating fluid within the joint cavity. The contributions of sulphated glycosaminoglycans to resistance were assessed by selective depletion by chondroitinase ABC, keratanase and heparinases I, II and III in vivo. Also, since glycosaminoglycans do not account fully for the resistance, the contribution of non-collagenous, structural proteins in interstitium was assessed by treatment with chymopapain, a collagen-sparing protease. 2. Ringer solution containing enzyme was injected into the synovial cavity of the knee in anaesthetized rabbits. After >= 30 min the intra-articular pressure was raised and the relation between pressure (Pj) and trans-synovial outflow (Qs) determined. The slope dQs/dPj at low pressures, i.e. below yield pressure, represents the hydraulic conductance of the lining, i.e. 1/resistance. The contralateral joint received Ringer solution without enzyme as a control. Action of enzymes on the tissue was confirmed by histochemical and immunohistochemical studies. 3. Treatment with chondroitinase ABC (5 joints) increased the hydraulic conductance of the lining by 2.3 times (control, 1.34 +/- 0.22 microliter l min-1 cmH2O-1; post-enzyme, 3.11 +/- 0.45 microliter l min-1 cmH2O-1). This was significantly less than the effects of leech, Streptomyces and testicular hyaluronidases, which caused an average 4.7 times increase (P < 0.001, ANOVA). Analogous findings were made above yield pressure. 4. Treatment with keratanase (3 joints) or heparinases I, II and III (3 joints) caused no significant increase in trans-synovial flows or conductance, even though the concentration of heparan sulphate in synovium is higher than that of chondroitin sulphates or hyaluronan. 5. Treatment with chymopapain (7 joints) caused the greatest increases in trans-synovial flow, which exceeded control flow by an order of magnitude in one case. After 0.1 U chymopapain the average conductance was 6.6 times the control conductance below yield pressure. Immunohistochemical studies confirmed that chymopapain treatment removed the synovial proteoglycans. 6. It is concluded that, despite their similar resistivities in vitro, the different glycosaminoglycans do not contribute equally, weight for weight, to interstitial resistance in vivo. Hyaluronan is the dominant glycosaminoglycan governing synovial interstitial resistance. In addition, non-collagenous structural proteins contribute significantly to interstitial resistance.

Hemarthrosis and hip joint pressure in femoral neck fractures.

In a prospective clinical study the intraarticular pressure of 55 patients with intracapsular femoral neck fractures was measured intraoperatively with the hip in different positions. Intraarticular hemarthrosis was quantified by a preoperative sonography examination. In 75% of the patients, increased intraarticular pressure caused by the hemarthrosis was found. The spontaneous median pressure increased significantly from 22 mm Hg with extension (28 mm Hg) and internal rotation of the hip joint (56 mm Hg). The lowest pressure was found in 70 degrees flexion (15 mm Hg). The median pressures increased within the first 24 hours after injury from 26 mm Hg in the first 6 hours to 46 mm Hg from 7 to 24 hours. Even in the first and second weeks after trauma, increased median pressures were detected (8.5 mm Hg and 13 mm Hg, respectively). No significant difference was found between undisplaced and displaced fracture types. Because increased joint pressure in other studies correlates with reduced perfusion of the femoral head, it can be deduced that reduction maneuvers without capsulotomy can compromise the circulation of the femoral head. Capsulotomy and osteosynthesis of the femoral neck at the earliest time possible is the best prophylaxis of tamponade. If the osteosynthesis is delayed, a preoperative sonography after admission and a control sonogram after 6 hours is recommended. In the event of relevant hemarthrosis, immediate therapeutic drainage is suggested for patients who will receive joint conserving osteosynthesis.

Superior-inferior stability of the shoulder: role of the coracohumeral ligament and the rotator interval capsule.

To study the superior-inferior stabilizing functions of the coracohumeral ligament (CHL) and the rotator interval capsule (RIC) with use of a material testing machine. The axial translations of the humerus with the superior-inferior translation force of 30 N applied were recorded under the following joint capsule conditions: (1) intact, (2) vented, (3) the CHL sectioned, and (4) the RIC incised in six cadaver shoulders. The order of sectioning was changed for conditions 3 and 4 in six other cadaver shoulders. With the arm in internal and neutral rotations, venting the capsule significantly increased the superior-inferior translation, which was unaffected by further sectioning of the CHL and the RIC. With the arm in external rotation, only the CHL contributed significantly to inferior stability, whereas both this ligament and the RIC contributed to superior stability to a lesser degree. The CHL is a stabilizer in superior inferior directions with the arm in external rotation, and the intra-articular pressure that is maintained by the intact RIC is a stabilizer in superior-inferior directions with the arm in internal and neutral rotations. These findings may provide a scientific background to support closure of the interval space to stabilize the shoulder and may explain part of the superior instability observed in shoulders with rotator cuff tears.

Massive intraperitoneal and extraperitoneal accumulation of irrigation fluid as a complication during knee arthroscopy

A case of uncommon fluid extravasation during knee arthroscopy leading to a swelling of the groin, scrotum, and penis, with massive intraperitoneal and retroperitoneal fluid accumulation is reported. A defective pump pressure sensor relay was found to be the cause of uncontrolled fluid delivery with excessive intra-articular pressure increase. The literature reports several cases of extravasation of irrigation fluid into the calf without any sequelae. Our patient experienced proximal expansion of the fluid that expanded along the vastus intermedius and shunted into the retroperitoneal and intraperitoneal space. There was no clinical evidence of compartment syndrome despite the excessive amount of extravasation in the thigh. Diuretics were administrated, and the fluid was excreted within 36 hours. The patient suffered of no further sequelae. Arthroscopy 1998 May-Jun;14(4):401-4

Avascular necrosis as a complication of septic arthritis of the hip in children.

Seventy-one hip joints in 69 infants and children with pyogenic arthritis were studied. Twenty joints (28%) with the radiographic characteristics of avascular necrosis were identified and the changes classified into 3 groups: Group 1 (infants up to the age of 6 months) had ischaemic changes characterized by the absence or delayed appearance of the epiphyseal ossification centre; Group 2 (children aged between 7 months and 5 years) showed disappearance of this centre whether followed by revascularization or not, with the shape of the cartilaginous femoral head preserved in either case; and in Group 3 (children 6-16 years of age) the femoral epiphysis was either totally or partially involved with increased bone density; collapse of the head may or may not have occurred. At follow-up for between 2 and 15 years, a trend towards more severe deformities was seen in the 11 hip joints of Group 3 when compared to the 9 hip joints in Groups 1 and 2. The opposite was observed in relation to less severe deformities. Early diagnosis and treatment of infection is mandatory in patients with pyogenic arthritis and increased intra-articular hydrostatic pressure, or those with septic thrombosis of the epiphyseal vessels, which could cause avascular necrosis (AVN).

Tensile properties of the knee-joint capsule at an elevated intraarticular pressure.

In order to evaluate the capsular reaction to high intraarticular pressure (IAP) in the knee during arthroscopy, we examined 13 patients admitted for elective surgery with joint infusion to 30, 70, 120 and 170 mmHg IAP (4, 9.3, 16 and 22.7 kPa). The infusion was repeated once, at all IAP levels except 30 mmHg, after 2 min and was recorded for another 2 min. A pressure-time curve was recorded as a combined effect of viscoelastic properties of the capsule and extraarticular fluid absorption. 3 more knee joints were infused directly to 170 mmHg and a pressure-time curve was recorded for 15 min, after which time the joint was reinfused to 170 mmHg in order to estimate the change in joint volume due to absorption or relaxation. In 10 knees, the curves were uniform. At infusion, the pressure curve was almost linear above 70 mmHg. There were no signs of plastic deformation of the joint capsule at pressures below 120 mmHg, while at 170 mmHg there were signs of capsular deformation. At each pressure level, the curve revealed a rapid fall in initial pressure that gradually decreased because of capsular relaxation or fluid absorption. Repeated infusion delayed the fall in pressure, due to increased capsular stiffness. In 3 knees infused directly to 170 mmHg IAP, the slope for the first 2 min of the pressure-time curve did not differ from that found at maximal IAP in knees examined with stepwise increasing pressures. Discontinuity of the capsule, even of puncture size, influenced the pressure/volume correlation considerably. We conclude that at IAP levels of 170 mmHg, there are signs of plastic deformation of the joint capsule. In order to avoid capsular damage, knee arthroscopy should be done at intraarticular pressure levels below 120 mmHg.

Dynamic glenohumeral joint stability

Stability of the glenohumeral joint with an anterior, posterior, and inferior displacement force of 50 N was measured in a dynamic shoulder model. Controlled hydrodynamic actuator forces were applied to the deltoid muscle and to the rotator cuff in seven anatomic specimens. During elevation of the arm the position of the humerus was measured with a sixdegree-of-freedom ultrasonic sensor device. The rotational center of the humeral head was used as a reference point for translation. A displacement force of 50 N led to significant humeral head displacement anteriorly and posteriorly but not inferiorly. A 50% reduction of rotator cuff forces increased anterior displacement by 46% and posterior displacement by 31%. Venting of the glenohumeral joint space and of the subacromial bursa resulted in a 50% increase of anterior displacement, a 19% increase of posterior displacement, and significant inferior displacement. This study demonstrates that in addition to passive stabilizers and negative intraarticular pressure, rotator cuff force significantly contributes to stabilization of the glenohumeral joint during arm motion. Muscle strength and coordination should gain more emphasis in the diagnosis and treatment of shoulder instability.

Holmium:YAG laser-assisted capsular shift in a canine model: Intraarticular pressure and histologic observations

The purpose of this study was to determine the initial effects of Holmium:YAG laser energy on the shoulder joint capsule. A new surgical procedure to correct shoulder joint instability uses Holmium:YAG laser energy to cause “shrinkage” of joint capsular tissues. To date there has been no information concerning an intraoperative measurable end point for the application of laser energy at surgery or the resultant depth and degree of tissue alteration. Seven greyhound dogs were used in this study. Preoperative intraarticular pressures (IAP) were measured on entry and after injection of 10 ml of solution. Laser energy was applied to the cranial medial glenohumeral ligament and joint capsule of all right shoulders with arthroscopic visualization. The unoperated left shoulders served as the control group. Six weeks after surgery pressure measurements were performed on both shoulders. A “second look” arthroscopy was performed on the shoulders. After euthanasia was performed, the anterior capsular tissues were harvested from both shoulders for histologic examination. The specimens were inspected by three blinded examiners. After 6 weeks the postoperative laser-treated IAP were higher than the same joint preoperative IAP in four of six dogs for both static nondistension and 10 ml distension measurements. At this same interval the marked tissue damage of the treated capsule was easily discerned by blinded observers. On histologic evaluation the laser-treated capsule showed synovitis and pericapsular tissue reactivity. The depth of the injury was beyond the joint capsule into the pericapsular tissue. It was not possible to determine the end point of the capsular “shrinkage” operation by combined pressure/volume intraoperative measurements. There was no uniform joint capsule compliance at 6 weeks. The histologic changes were extensive in both magnitude and depth. Future studies in this animal should include decreased laser energy plus other means of monitoring the intraoperative effects of laser use.

Radiocarpal articular pressures during the reduction of distal radius fractures.

To measure in vivo radiocarpal articular pressures during closed reduction and external fixation of distal radius fractures. Intraoperative measurements using a sterile pressure sensitive sensor specially constructed for this application. Ten patients with a closed distal radius fracture stabilized by radiometacarpal external fixation. Radiocarpal pressures measured during transarticular distraction, wrist palmar flexion, wrist ulnar inclination, and fracture reduction. Transarticular distraction resulted in a substantial decrease of the articular pressure, averaging -158.1 mmHg. Palmar flexion resulted in a mean pressure increase of 91.8 mmHg. The reduction of the fracture using a combination of distraction, palmar flexion and ulnar deviation resulted in either an increase or decrease of articular pressure, but always with a tendency toward progressive normalization of the pressure, with a mean slope of 3.2 mmHg/min. The phenomena leading to the reduction of distal radius fractures could be related in part to a decrease of the intraarticular pressure, which may be responsible for a suction effect on the intraarticular bone fragments.

Tenodeses do not fully restore ankle joint loading characteristics: a biomechanical in vitro investigation in the hind foot

Objective. In order to understand the biomechanical consequences of ligament injuries and surgical reconstruction procedures, their effects on intra-articular loading in the ankle joint complex and Chopart joint lineand on the plantar pressure patterns were investigated in vitro. Methods. Twelve fresh-frozen lower leg specimens were freed of soft tissue down to the malleoli and prepared for accessing the talocrural, subtalar, talonavicular and calcaneocuboid joints. The specimens were fixed in a loading simulator and axially loaded with 600 N in six experimental conditions: intact; after cutting the anterior talofibular ligament; after additionally cutting the calcaneofibular ligament; after performing three common types of tenodeses, the Evans, Watson-Jones and Chrisman-Snook procedures. The intra-articular loading characteristics were determined with pressure sensitive film. Plantar loading patterns were measured with a capacitive EMED pressure distribution platform. Results. Average intra-articular pressures were increased and were related either to decreased contact areas or to increased contact forces found in all joints after ligament resections and tenodeses. Plantar loading was increased under the medial aspect of the foot and decreased under the midfoot region. Conclusions. The results indicate that ankle ligament injuries, as well as surgical reconstructions by tenodeses, affect joint loading characteristics and may exacerbate joint degeneration.

The relation between the position of the glenohumeral joint and the intraarticular pressure: An experimental study

Intraarticular pressures of the glenohumeral joint were measured in 15 cadaveric shoulders during passive movement of the humerus and under various inferiorly directed loads on the humerus. With a fiber-optic transducer-tipped catheter and an airtight connector, the basic intraarticular pressure was measured directly without injection of any physiological saline solution into the joint before measurement. The initial intraarticular pressures were all negative with a mean value of −67.8 mm Hg. During abduction-adduction movement the minimal intraarticular pressure was measured at 20° of humeral abduction. During rotation the minimal intraarticular pressure was observed at neutral humeral rotation. The intraarticular pressure decreased nearly linearly with increasing inferior load on the humerus. These results indicate that the intraarticular pressure takes part in stabilization of the glenohumeral joint, and the negative intraarticular pressure of the glenohumeral joint induces the maximal stabilizing effect at 20° of humeral abduction and neutral humeral rotation.

Influence of isokinetic and ergometric exercises on oxygen partial pressure measurement in the human knee joint.

We conducted the first in vivo investigation on the influence of joint movement on intraarticular oxygen partial pressure. The development of a special flexible microcatheter allowed measurements of intraarticular oxygen partial pressure under both physiological and pathological conditions. The aim of this study was to evaluate the influence of different knee joint stresses on intraarticular oxygen partial pressure under physiological (healthy patients) and pathological (patients with osteoarthritis) conditions. The results show that the different exercise patterns influence the intraarticular oxygen partial pressure. Patients with osteoarthritis showed a lower increase of intraarticular oxygen partial pressure compared with healthy patients. This phenomenon is directly correlated to the degree velocity of the isokinetic exercises. We found the same results under ergometric conditions. This method allows functional, intraarticular in vivo measurements under different exercise patterns. For the first time, we were able to measure the influence of joint movement on the intraarticular process of nutrition under physiological and pathological conditions. Also, to evaluate for the first time in vivo different concepts for osteoarthritis therapy.