Intracapsular Pressure Research Articles

A Rabbit Model for Capsular Contracture: Development and Clinical Implications

Capsular contracture remains one of the most common complications involving aesthetic and reconstructive breast surgery; however, its cause, prevention, and treatment remain to be fully elucidated. Presently, there is no accurate and reproducible pathologic in vitro or in vivo model examining capsular contracture. The purpose of this study was to establish an effective pathologic capsular contracture animal model that mimics the formation of capsular contracture response in humans. New Zealand White rabbits (n = 32) were subdivided into experimental (n = 16) and control groups (n = 16). Each subgroup underwent placement of smooth saline mini implants (30 cc) beneath the panniculus carnosus in the dorsal region of the back. In addition, the experimental group underwent instillation of fibrin glue into the implant pocket as a capsular contracture-inducing agent. Rabbits were euthanized from 2 to 8 weeks after the procedure. Before the animals were euthanized, each implant was serially inflated with saline and a pressure-volume curve was developed using a Stryker device to assess the degree of contracture. Representative capsule samples were collected and histologically examined. Normal and contracted human capsular tissue samples were also collected from patients undergoing breast implant revision and replacement procedures. Tissue samples were assessed histologically. Pressure-volume curves demonstrated a statistically significantly increased intracapsular pressure in the experimental group compared with the control group. The experimental subgroup had thicker, less transparent capsules than the control group. Histologic evaluation of the rabbit capsule was similar to that of the human capsule for the control and experimental subgroups. The authors conclude that pathologic capsular contracture can be reliably induced in the rabbit. This animal model provides the framework for future investigations testing the effects of various systemic or local agents on reduction of capsular contracture.

Automated Irrigation/Aspiration Before Phacoemulsification in Eyes With White Cataracts

A white mature cataract still presents a significant challenge for the cataract surgeon. Because of the reduced visibility and increased intracapsular pressure in such cases, it is difficult to consistently achieve controlled continuous curvilinear capsulorhexis. Several simple procedures for treatment of eyes with white mature cataract are described. Seven consecutive patients (7 eyes) with white cataracts were enrolled for cataract surgery from July 2002 to February 2003. A small, central anterior capsular opening was created after carefully filling the anterior chamber with viscoelastic agents. Automated irrigation/aspiration by lowering of a connected bottle of balanced salt solution was used to aspirate the liquefied milky lens contents and decrease intracapsular pressure. All patients obtained controlled capsulorhexis, safe cataract phacoemulsification, and in-the-bag intraocular lens implantation. Automated irrigation/aspiration before phacoemulsification is safe and effective for eyes with white cataracts.

Increased intraarticular pressure reduces blood flow to the femoral head.

Hemarthrosis leading to increased intracapsular pressure after an undisplaced femoral neck fracture is suspected to impair blood flow to the femoral head and may lead to osteonecrosis. We hypothesized that an increase of intraarticular pressure would reversibly decrease the blood flow to the femoral head. Eleven patients having surgical dislocations for treatment of femoroacetabular impingement were included in this study. Saline was injected into the intact intracapsular space while the blood flow to the femoral head was recorded using laser Doppler flowmetry. Injection of saline resulted in an increase in the intracapsular pressure. The injected volume of normal saline until disappearance of the pulsatile signal was on average 20 mL (range, 10-35 mL) with an average intraarticular pressure of 58 mm Hg (range, 25-88 mm Hg). Aspiration of the joint resulted in a return of the pulsatile flow. Hemarthrosis after undisplaced intracapsular fractures of the femoral neck are likely to cause an increase in intracapsular pressure. Decompression of the hematoma to reduce the intracapsular pressure is strongly advocated to optimize blood flow to the femoral head in acute fractures.

Topical, single dose bisphosphonate treatment reduced bone resorption in a rat model for prosthetic loosening

Fluid pressure, instability or particles have been suggested to cause peri-prosthetic bone resorption. High intracapsular pressures have been reported in hip joints with loose prosthetic components, and oscillating fluid pressure has been shown to cause dramatic bone resorption in animal models. Resorption can be reduced by systemic bisphosphonate treatment in rat models with oscillating fluid pressure, but this has required higher doses than needed to inhibit normal remodelling. Bisphosphonates have high affinity to bone mineral. Topical application of the drug is therefore feasible. We used a previously described rat model where oscillating fluid pressure causes bone resorption. Before pressurization, a 1 mg/ml solution of alendronate was applied onto the bone surface for 1 min, after which excess bisphosphonate was rinsed away. Bone resorption was measured on histological slides as soft tissue area at the interface. Rats treated with topical alendronate had soft tissue areas reduced by half. Topical bisphosphonate treatment before cementing a joint implant could possibly reduce the risk of later loosening.

Continuous curvilinear capsulorhexis in intumescent or hypermature cataract with liquefied cortex

We describe a technique to prevent milky liquefied cortical matter from obscuring the view of the anterior chamber and radial tears caused by high intracapsular pressure in eyes with hypermature or intumescent cataract. The continuous curvilinear capsulorhexis (CCC) is created in a sealed anterior chamber without capsule staining or viscoelastic material. Ninety-four consecutive CCCs were performed by a single surgeon over 24 months using the method. A successful CCC was achieved in all eyes. Four cases had complications that occurred late in the surgery and were not related to the CCC.

Muscles may contribute to shoulder dislocation and stability.

Joint instability is one of the most common human afflictions, affecting not only the hip, knee, and shoulder but all joints of the body. Surgical repair for joint instability is done commonly, yet has not been able to restore function consistently. Pain, recurrence of instability, joint stiffness, muscle injury, and degenerative joint disease are all too common sequelae. Because the glenohumeral joint is most commonly dislocated, efforts have been directed to understanding shoulder instability. Study has included not only the static restraints (capsulolabrum, articular surfaces, intracapsular pressure), but also their important interplay with the dynamic restraints (shoulder muscles). Furthermore, not only were muscles known to stabilize the joint studied but also may have contributed to dislocation. An in vitro, cadaveric model that included relevant shoulder muscles and a mechanism of dislocation similar to an in vivo mechanism was developed. The capsulolabral pathoanatomy that occurred after dislocation was studied. Increased understanding of joint dislocation may improve functional results after rehabilitation and surgical repair, not only at the shoulder, but also at all other joints.

In Situ Fixation of Nondisplaced Intracapsular Fractures of the Proximal Femur

The Garden classification of femoral neck fractures is used most commonly in the literature. However, there is difficulty in differentiating the four types of fractures as shown by studies of interobserver reliability. Therefore, it may be more accurate to classify femoral neck fractures as nondisplaced (Garden Types I and II) or displaced (Garden Types III and IV). Nondisplaced femoral neck fractures (Garden Types I and II) should be stabilized internally using multiple (two to four) lag screws. Care should be taken to avoid any loss of reduction during the surgical procedure. Decompression of the hematoma by needle aspiration or capsulotomy has been shown to reduce intracapsular pressures and improve blood flow in the femoral head. However, from the practical point of view, there currently is insufficient evidence to justify capsulotomy. Complications after in situ fixation of nondisplaced femoral neck fractures can be divided into two categories: general complications relating to comorbidities, surgery, or anesthesia; and complications after the use of cannulated screws such as unrecognized screw penetration of the hip, infection, nonunion, and osteonecrosis.

Ovarian bivalving after detorsion

Objective: To assess the efficacy of a new technique, ovarian bivalving, on facilitating adnexal recovery after adnexal torsion. Design: Retrospective case series. Setting: Academic medical center. Patient(s): Five patients undergoing conservative surgical management of adnexal torsion at the Children’s Hospital, Boston, Massachusetts, from May 1999 to April 2000. Intervention(s): Performance of ovarian bivalving after untwisting of adnexal torsion. Main Outcome Measure(s): Sonographic appearance of adnexa after ovarian bivalving, and postoperative complications. Result(s): After surgical treatment, four of five patients undergoing untwisting of adnexa and ovarian bivalving had sonographically confirmed normal follicular function; in three of five cases, it was confirmed with Doppler arterial flow. There were no postoperative complications. Conclusion(s): After the untwisting of ischemic adnexa, ovarian bivalving is an effective technique to decrease ovarian intracapsular pressure, increase arterial perfusion, and facilitate adnexal reperfusion and recovery.

Cataract surgery and the "Blue Miracle"

Continuous circular capsulorhexis enabling safe phacoemulsification and implantation of the PC-IOL in the bag is extremely difficult to perform in the absence of red reflex. Staining of the anterior capsule with a vital dye (Vision blue(R); DORC, The Netherlands) allows easy capsulorhexis under such conditions. Because of missing or poor red reflex Vision blue(R) was applied to allow capsulorhexis in 26 eyes of 25 patients (aged 24 - 86 years). Sixteen patients had mature cataracts, two patients had dense vitreous opacities and 8 patients had pronounced anterior subcapsular opacifications. Continuos circular capsulorhexis was easy to perform in 22/26 eyes after staining the anterior capsule with Vision blue(R). Due to increased intracapsular pressure two eyes developed an uncontrolled tearing of the anterior capsule towards the periphery, and in two eyes capsulotomy had to be completed with high-frequency capsulotomy or scissors. Ten of sixteen eyes with mature cataracts had extremely hard nuclei requiring extended phacoemulsification time (more than 90 seconds calculated for 100 % power). There was no rupture of the posterior capsule nor vitreous loss. All PC-IOL's (23 x Acrysof(R); Alcon; 3 x 6.5 mm PMMA) were implanted into the capsular bag. Preoperatively 19/26 eyes had visual acuity of handmotions or less, postoperatively 18/26 eyes achieved 20/30 or better visual acuity. In the absence of red reflex staining of the anterior capsule with Vision blue(R) allows continuous circular capsulorhexis and implantation of the PC-IOL in the bag. An extremely hard nucleus requiring extended phacoemulsification time must be expected in elderly patients with mature cataracts.

Traumatic transepiphyseal fracture of the femoral neck in early adolescence

Acute traumatic fractures of the femoral neck in children and adolescents with a separation of the upper femoral epiphysis are very rare. Due to the vulnerability of the supplying femoral circumflex artery the prognosis is bad, with avascular necrosis and coxa vara leading to permanent deformity. We describe a case of a 12-year-old boy who sustained a left transepiphyseal fracture with complete separation (Delbet's type I) of the femoral head at the epiphysis. Reduction was achieved under general anaesthesia, capsular haematoma was removed and the displaced epiphyseal fragment was fixed by Kirschner wires. To guarantee a fast recovery of the blood supply for the femoral head an immediate and cautious treatment in this rare fracture type is proposed. If closed reduction is insufficient, only minor traumatizing techniques such as Kirschner wires should be used for the fixation of the epiphyseal fragment in ordner not to cause more intracapsular pressure.

Early postoperative capsular block syndrome related to saccadic-eye-movement-induced fluid flow into the capsular bag

PurposeTo determine the relationship between saccadic eye movements and the development of early postoperative capsular block syndrome. SettingFundacion Oftalmologica, Los Andes, Santiago, Chile. MethodsAn artificial experimental setup was designed to reproduce the anatomical, hydrodynamic, and kinetic conditions of an early postoperative pseudophakic eye with a capsulorhexis and intracapsular intraocular lens (IOL) implantation. An electromechanical transducer driven by a digital-to-analog converter was used to mimic saccadic eye movements at physiological speeds and accelerations. Position information and differential pressure measurements between the intracapsular space and the extracapsular space were digitized. Various anterior capsule–IOL configurations were tested including partial adhesion of the anterior capsule to the lens. ResultsSaccadic movements increased intracapsular pressure by displacing fluid into the capsular bag. This finding was inconstant and only observed when the capsular rim adhered to the IOL optic by more than 70%. Development of positive intracapsular pressure was noted above 4 mm Hg. ConclusionA valve-like mechanism formed by the capsulorhexis rim partially adhered to the IOL optic can occur postoperatively. Under these conditions, saccadic eye movements can increase intracapsular pressure by a unidirectional inertial displacement of fluid into the capsular bag.

Effect of circumferential plasma-spray porous coating on the rate of femoral osteolysis after total hip arthroplasty.

Osteolysis of the femur has been a serious problem associated with some designs of total hip-replacement implants; it frequently leads to failure of the femoral component. We evaluated the effect of a circumferential plasma-spray porous coating on the rate of osteolysis in a study that included two groups of hips, each of which received an implant with the same design except for the extent of the porous coating. Our goal was to determine the possible role of circumferential porous coating in protecting the bone-implant interface from osteolysis. A series of consecutive primary total hip replacements performed with insertion of the Mallory-Head implant without cement was divided into two study groups. The first 126 hips (Group 1) were treated with a femoral stem that had a noncircumferential plasma-spray porous titanium coating. The next ninety hips (Group 2) were treated with a circumferentially coated stem of the same design. The average duration of radiographic follow-up was 7.8 years in Group 1 and 7.5 years in Group 2. The average rate of polyethylene wear was similar for the two groups (0.187 millimeter per year in Group 1 and 0.189 millimeter per year in Group 2). The prevalence of osteolysis in Group 1 (40 percent; fifty of 126 hips) was significantly higher than that in Group 2 (10 percent; nine of ninety hips) (p < 0.001). Osteolysis remote from the joint space (distal to zones 1 and 7) was found in 11 percent (fourteen) of the hips in Group 1 but in none of those in Group 2 (p = 0.0004). The average total area of osteolysis in Group 1 (5.0 square centimeters) was significantly larger than that in Group 2 (2.9 square centimeters) (p < 0.05). A circumferential plasma-spray titanium porous coating on the femoral component of a total hip-replacement prosthesis inserted without cement appears to provide an effective barrier preventing wear debris from gaining access to the endosteal surface of the femur and the greater trochanter. This finding supports the hypothesis of the so-called effective joint space, which predicts that wear debris from the joint bearing can migrate, driven by intracapsular pressures, to all areas to which joint fluid has access and thus can result in osteolysis. The reduction of the prevalence of osteolysis and the elimination of osteolysis from the zones remote from the joint space by the use of a circumferential plasma-spray porous coating indicates that the femur was effectively sealed off from the joint space. We believe that the durability and longevity of the femoral component should be enhanced by the use of such a coating.

Significance of Synovitis in Legg-Calve-Perthes Disease

Synovitis is an important feature in Legg-Calvé-Perthes disease (LCPD) with a significant prognostically negative impact on clinical symptoms, cartilage biochemistry, mechanical properties of the cartilage, joint biomechanics, and prognosis toward healing with a congruent, spherical head of femur. Synovitis causes cartilage edema, deterioration of the cartilage's mechanical properties, cartilage hypermetabolism, and, subsequently, cartilage hypertrophy. This sequence of events could explain the clinical course, which consists of cartilage hypertrophy, lateral subluxation, anterolateral deformation of the head, and, subsequently, joint incongruence in prognostically poor cases of LCPD. A factor in the deformation of the hypertrophic cartilage of the epiphysis is decreased range of motion of the hip, because of pain caused by the increase in intracapsular pressure and the subsequent decrease in the "molding" ability of the acetabulum. Synovitis in LCPD causes an increased intracapsular pressure, the magnitude of which may, in some patients, intermittently compromise the blood supply to the proximal femoral epiphysis. Whether synovitis is the consequence of, or precedes, the loss of blood supply and epiphyseal necrosis is not yet established. Significant and persistent synovitis during the entire course of the disease emphasizes the importance of magnetic resonance imaging as the method of choice for the diagnosis and the prognosis, as well as the monitoring of therapy. The prognostically negative effects of synovitis suggest that more therapeutic efforts should be focused on the treatment of synovitis, from a palliative and prognostic point of view.

Surgical techniques for difficult cataracts.

This article reviews some of the advances that have taken place in the surgical techniques for difficult cataracts such as rock-hard, white, and posterior polar cataracts. Fashioning a central space, modified chopping maneuvers, and creation of multiple small fragments have enabled the surgeon to consistently achieve a successful outcome. A judicious combination of chop and separation movement in a step-by-step manner reduce the stress of the procedure and make it safer. Raised intracapsular pressure and poor visibility are dealt with through various innovative techniques. Use of high-viscosity sodium hyaluronate and double capsulorhexis allow the surgeon to achieve capsulorhexis with a high success rate. A controlled and gentle approach to phacoemulsification has proven to be the key factor for success in posterior polar cataracts.

Phacoemulsification of white mature cataracts

Purpose: To evaluate the intraoperative difficulties associated with phacoemulsification of white mature cataracts and develop a strategy for consistently achieving continuous curvilinear capsulorhexis (CCC) in these cases.Setting: Raghudeep Eye Clinic, Iladevi Cataract & IOL Research Centre, Ahmedabad, India.Methods: This prospective study comprised 60 eyes of 60 patients with senile white mature cataract. Mean follow-up was 7 months. Detailed preoperative and intraoperative notes were made including intraoperative subjective assessment of the intracapsular pressure and cataract hardness. A small capsulorhexis was attempted initially. Endophacoemulsification was performed using the stop, chop, chop, and stuff technique. The capsulorhexis was enlarged before intraocular lens implantation. An initial cut in the capsulorhexis margin was made with a cystotome needle while a spatula supported the anterior capsule. The capsulorhexis was then enlarged with forceps.Results: A CCC was achieved in 57 eyes (95%). Intracapsular pressure was judged to be raised in 24 eyes (40%). Of these, CCC was accomplished in 21 eyes (88%). Statistical analysis confirmed that raised intracapsular pressure was a significant factor. Capsule opacification or plaque was detected at the end of the surgery in 20 eyes (33%); 50% of the nuclei were of grade 5 hardness.Conclusion: If a CCC can be achieved, the results of white cataract phacoemulsification are comparable to those of routine cataract surgery. When using the two-stage technique, one should be prepared to deal with a hard cataract through a small capsulorhexis.

Intracapsular pressure in congenital dislocation of the hip.

Intracapsular hip joint pressure was measured in six infants with congenital dislocation of the hip (CDH) or acetabular dysplasia with hip joint instability diagnosed at an average of 4.3 months of age (range: 3-8 months). In the extension and neutral rotation position, the mean pressure was 8.9 mm Hg. After reduction, obtaining stability with the hip joints in the "frog-leg" position (i.e., maximum flexion around the axis of the neck of the femur), the mean pressure was 74.6 mm Hg. When obtaining stability with the hip joints in 20 degrees of flexion, abduction, and inward rotation, the mean pressure was 104 mm Hg, and in approximately 20 degrees of flexion, abduction, and forced inward rotation it was 160 mm Hg. We conclude that these rotational positions, often used to retain the joint in CDH or hip joint instability, induce intracapsular pressures that may cause occlusion of epiphyseal-physeal vessels and thus may be responsible for the avascular epiphyseal necrosis and growth disturbance seen in these patients.

Biomechanics of the hip joint capsule —a mathematical model and clinical implications

Objective. Our aim was to develop a mathematical model to calculate forces, tension and stretching in the hip joint capsule, under conditions caused by the joint effusion usually accompanying hip disease. Design. A mathematical model was developed, based on experimental data from cadaver studies. Background. Intracapsular pressure is important with respect to the degree of painless movement in the hip. Previously, we established the relations between the rotation around the axis of the neck of the femur, joint effusion, intracapsular pressure and joint stability. Methods. In six cadaver adult hips the joint distraction, the traction force along and the rotation around the axis of the neck of the femur and the intracapsular pressure, were simultaneously monitored as the volume of intracapsularly infused saline was increased. The elasticity-constants included in the extracted formula for the fluid pressure were calculated in a designed computer software based on these experimental data. Results. Presented in Figures 3–12. Conclusions. In the normal joint there is no increase in intracapsular pressure, nor any tension in the hyperboloid shape capsule within the normal range of rotation around the axis of the neck of the femur. This shape is distorted in a hip with effusion, rotation then resulting in an increased intracapsular pressure and tension in the capsule, with potential risk of ruptures.

Intracapsular hip pressure after femoral neck fracture.

A consecutive series of 34 patients with femoral neck fractures was included in a prospective study aimed at evaluating preoperative variations in intracapsular pressure after changes in hip position, hip traction, and aspiration of hemarthrosis and their influence on the development of femoral head necrosis. Patients were observed for 7 years after surgery. Before aspiration, the mean intracapsular pressure in the antalgic physiologic position was 44.4 mm Hg. There were no differences between displaced and undisplaced fractures. The pressure was a maximum (mean value, 124.8 mm Hg) with the hip in extension and inward rotation, this pressure being greater than the blood systolic pressure in most cases. Hip traction of 3 kg in the antalgic physiologic position was found to be highly effective in preventing any bone flow tamponade effect in displaced and undisplaced femoral neck fractures: the mean intracapsular pressure decreased to 28.5 mm Hg. Aspiration of the hemarthrosis induced a significant decrease in intracapsular pressure only in cases with impaired vascularity of the femoral head as measured by scintigraphy using 99mTc labeled methyldiphosphonate. Aspiration of the hemarthrosis therefore is indicated only in the above cases, although it is less effective than hip traction in the antalgic position. There was no significant correlation between intracapsular pressure and the scintigraphy ratio. Avascular necrosis of the femoral head was detected in six cases. Among these, five patients had an intracapsular pressure below their diastolic blood pressure. This could indicate that vascular damage related to the fracture could be an important cause of bone necrosis despite that blood supply can be decreased by a tamponade effect.

Intracapsular pressure and loosening of hip prostheses. Preoperative measurements in 18 hips.

We measured the intracapsular pressure preoperatively in 18 hips (17 patients) before revision of a total hip arthroplasty because of aseptic loosening. Distension of the joint capsule was measured with sonography in 13 cases. In extension, the mean intracapsular pressure was 26 (0-60) mmHg, in extension and inward rotation it was 159 (24-280) mmHg, in extension and outward rotation it was 30 (3-67) mmHg and in 45 degrees of flexion it was 12 (0-28) mmHg. A mean of 6 (0.5-20) mL of joint fluid was aspirated after the pressure measurements. Sonography showed increased joint fluid/synovial edema and/or increased capsular thickness, as compared to 34 unrevised, radiographically not loose prosthetic hips, and that the capsular distension correlated to intracapsular pressure during extension and inward rotation. We conclude that the intracapsular pressure usually is elevated in a hip joint with loose prosthetic components, that the intracapsular pressure varies with the position of the hip and that capsular distension reflects increased intracapsular pressure. The increased and often very high pressure, varying during gait, may pump debris away from the joint along the interfaces and even by itself cause osteolysis and loosening.

Legg-Calvé-Perthes' disease—synovitis, cartilage, remodeling

This thesis evaluates and correlates the findings in a series of children with Legg-Calve-Perthes´ Disease at the Departments of Orthopedics, University Hospitals in Lund, Sweden and Odense, Denmark during 1984-1993. It focuses on the importance of synovitis and its effect on the cartilage, on the shape of the femoral head in the early phases of LCPD and on femoral head remodeling after proximal femoral varus derotation osteotomy. Synovitis, i.e.inflammation and edema of the synovium with or without joint effusion, can be diagnosed sonographically in LCPD. Significantly increased concentrations of proteoglycan fragments and stromelysin-1 in hip joint effusions, confirms the presence of synovitis. It causes an increase in intracapsular pressure, the magnitude of which may intermittently compromise the blood supply to the proximal femoral epiphysis and metaphysis. Synovitis persists late in the course of the disease and seems to be an important factor as regards symptoms and prognosis; It causes pain and decreased range of motion and, if persistent, contracture of the joint. Moreover, synovitis may be responsible for the cartilage hypertrophy and subsequent lateral subluxation with poor containment, deformation and incongruency. Consistent signs of fat necrosis in the proximal metaphysis with reactive, reparative changes, indicates previous episodes of ischemia in a prognostically poor subset of LCPD. The bony shape seen on conventional radiography does not adequately reflect the cartilage shape of the femoral head on MRI or on arthrography. MRI provides early and reliable information about the cartilaginous outline of the head of the femur, thus constituting a potential, early prognostic tool. MRI also provides earlier and more reliable information on the remodeling of the femoral head in LCPD than conventional radiography does. In a subset of prognostically poor cases of LCPD, there is an early, continuous spherical remodeling of the femoral head following proximal femoral varus derotation intertrochanteric osteotomy.