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Background and Purpose: The role of synovitis and high fluid pressure in the loosening process after total hip arthroplasty has gained increasing attention. We investigated the correlation between head size, polyethylene wear, and capsular distention., Patients and Methods: We analyzed 39 unrevised, radiographically stable hips that had been operated with 28 or 32 mm femoral heads 10 years earlier because of osteoarthritis. We evaluated radiographic signs of loosening, linear and volumetric polyethylene wear, body mass index, activity level, and age. Sonographic examination was performed to measure capsular distance i.e. the distance between the prosthetic femoral neck and the anterior capsule., Results: Linear wear was 0.09 mm/year and 0.18 mm/year in the 28 mm and 32 mm groups, respectively (p < 0.001). The volumetric wear was 51 mm(3)/year and 136 mm(3)/year (p < 0.001) and the capsular distance was 13 mm and 17 mm, respectively (p < 0.001). There was a correlation between linear wear (r = 0.54), volumetric wear (r = 0.62), and capsular distance (p < 0.001)., Interpretation: Wear was greater for the larger femoral head and was correlated to capsular distension.

Objective: To compare implant survival rates after total hip arthroplasty with Exeter matte or polished stems and to determine the relationship of synovitis/joint effusion to signs of implant loosening and stem type., Material and Methods: The first part of the study included retrospective revision rate analysis of 118 primary hip replacements performed during 1991-1995. Two different designs of Exeter stems were used: matte surface stems during 1991-1995 (matte surface group--47 cases), and polished stems during 1992-1995 (polished stem group--71 cases). During the second part of the study, 24 patients (11 in polished stem group and 13 in matte stem group) were prospectively examined with radiography and sonography. Sonography was performed in order to evaluate capsular distension, i.e. the distance between prosthetic femoral neck and anterior capsule. Capsular distension depends on synovitis and/or synovia in prosthetic hip. The relationship between capsular distension, stem type, and radiographic signs of loosening was assessed., Results: For the first part of our study, total implant survival was 78% with matte stems and 61% with polished stems 13 years postoperatively (P=0.27). Stem survival was 82% for matte stems, and 88% for polished stems (P=0.54). In the second part of study, a significant relationship between increased capsular distension and cup loosening was determined (P=0.04). We did not find significant difference in capsular distension when compared matte and polished stems., Conclusion: Implant survival rates did not differ between the groups. The relationship between capsular distension and cup loosening was statistically significant.

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.

Forty-six patients (48 hips), operated on with cemented total hip arthroplasty (THA) because of arthrosis, were examined radiographically and sonographically at 10-year follow-up. Polyethylene wear of acetabular cups was measured on conventional non-weight-bearing pelvic radiographs, and the volume of polyethylene debris was calculated. Radiographic signs of loosening were identified. The capsular distance (ie, thickness of the synovium or synovial contents) was measured sonographically. We found a significant correlation between increased volumetric wear and increased capsular distance. Hips with radiographically loose acetabular components had significantly greater volumetric wear and capsular distance than those without signs of acetabular loosening. This relationship was not observed in hips with radiographically loose femoral components. In cemented THA, the volume of polyethylene wear debris and the thickness of the synovium and the synovial contents are related. In the event of radiographic loosening of the acetabular component, they are both increased.

Purpose: To evaluate, by means of MR imaging, the degree and persistence of synovitis in the hip joint in Legg-Calvé-Perthes disease and to correlate the degree of synovitis with the degree of epiphyseal necrosis., Material and Methods: A total of 170 MR images in 72 patients (84 hips) were examined. The T2-weighted MR images were taken in the coronal plane in order to evaluate the degree of synovitis in the hip joint., Results: MR revealed synovitis in all cases in the early phase of the disease. In Catterall group II, synovitis was discreet to moderate for up to 6 months after diagnosis. Hips with more severe necrosis, Catterall groups III and IV, had moderate or intense degrees of synovitis. There was a correlation between the degree of synovitis and the lateral pillar classification according to HERRING et al. Also, there was a good correlation between the extent of signal changes in the epiphysis on MR imaging and the degree of synovitis. There was no difference when signal changes were evaluated on T1- or T2-weighted images. Signs of synovitis could be seen for up to 30 months after diagnosis in Catterall group I hips, and in Catterall groups II and III for up to 36 months, and in 2 cases even longer. Some Catterall group IV hips had discreet or mild synovitis for 60 months or more, after diagnosis., Conclusion: The degree of synovitis on MR imaging correlates to the extent of epiphyseal necrosis seen on radiographs or MR imaging as well as to the lateral pillar classification, i.e. to a poor clinical outcome. In Catterall group IV hips, synovitis can even persist for up to 60 months after diagnosis.

Twenty-one children with transient synovitis of the hip were treated in two consecutive groups. In 12 patients aspiration of the synovial effusion was performed within 24 h of admission. In a second group of nine patients no aspiration was performed. There was no other difference in treatment. Joint effusion was studied sonographically in comparison with the nonsymptomatic contralateral hip. Sonography was performed immediately after admission, within 12 h after aspiration, and repeatedly during a follow-up period of up to 15 days. Following aspiration the capsular distention decreased to 49% but recurred within 24 h to 72% of the preoperative value. However, during the first 4 days of follow-up the capsular distention in the aspirated cases was significantly and permanently lower than in the nonaspirated cases. We conclude that arthrocentesis in the acute stage of transient synovitis of the hip in the child permanently reduces the intracapsular effusion.

39 children with Legg-Calvé-Perthes Disease (LCPD) and with a radiographically unsatisfactory development were examined with sonography regarding synovitis and with intracapsular pressure recording and aspiration performed 15 (2-36) months after the onset of symptoms. The mean anterior sonographic capsular distension was 3.0 (1.0-7.0) mm greater than that of the contralateral, asymptomatic hip. The mean intracapsular pressure was 4.5 (0-11.5) kPa with the hips in extension and neutral rotation, 9.7 (1.3-27.3) kPa with the hips in extension and inward rotation and 0.9 (-0.8-4.7) kPa in 45 degrees of flexion. We conclude that these children have synovitis as diagnosed sonographically. This synovitis is probably symptomatically and prognostically important in LCPD due to increased intracapsular pressure, with pain, a decreased range of motion and, potential joint contracture.

In a 7-year-old boy with clinical symptoms of transient synovitis of the hip, an intracapsular effusion was diagnosed with computed tomography and ultrasonography. An intracapsular pressure of 50 mmHg was recorded prior to aspiration of 5.5 ml of clear fluid. Repeated ultrasonography immediately after aspiration verified a reduction in effusion, and serial examinations on the following days did not reveal any recurrence of the effusion.

Fourteen consecutive children with symptoms of transient synovitis of the hip were examined with sonography regarding intracapsular effusion, with scintimetry regarding blood-flow in the proximal femoral epiphysis (PFE) and with intracapsular pressure recording and aspiration. All patients had an intracapsular effusion. Intracapsular pressure was found to depend on the position of the hip. The mean pressure with hips in extension and inward rotation was 22.6 kPa (170 mm Hg) whereas in 45 degrees of flexion it was 2.3 kPa. In two cases scintimetry demonstrated reduced blood flow to the PFE; after aspiration, isotope uptake returned to normal, indicating that increased intracapsular pressure has a harmful effect on circulation to the PFE. Children with transient synovitis should be treated with the hips in 45 degrees of flexion to reduce intracapsular pressure. Forcing the hip in extension causes a risk of ischaemia of the PFE.

Fifty-five consecutive children presenting with transient synovitis of the hip were examined with 99mTc-MDP scintigraphy and pin-hole collimator technique. Quantitative assessment was performed along a profile of interest across the hip joint. The criteria for the normal scintimetric pattern in the child's hip were established and the pathologic pattern of uptake in the acute phase, as well as in the follow-up after synovitis, was described. A decrease in isotope uptake in the proximal femoral epiphysis was observed in 13 children. This was correlated with a reduced uptake in the growth-plate, indicating a disturbance of blood supply to these regions. A characteristic pattern of isotope uptake with duration of symptoms was observed: a decrease in uptake during the first week followed by rebound hyperemia within 1 month. One child developed osteonecrosis (Legg-Calvé-Perthes disease).

Sonography was used successfully in the investigation of septic conditions in the hip region of four children. In two patients, septic arthritis of the hip was confirmed; in two patients, intracapsular involvement was excluded in osteomyelitis of the hip region.

The levels of proteoglycan antigen were measured in joint aspirates from the hip of children with transient synovitis, septic arthritis, Legg-Calvé-Perthes' disease and congenital and traumatic dislocation. Significantly increased levels were found in children with transient synovitis and septic arthritis as compared with other conditions. We propose that the proteoglycan antigens in the joint fluid were released from the articular cartilage in a partially degraded form as a result of an increased rate of proteolytic degradation. In transient synovitis, the source of proteolytic activity may be chondrocytes activated by factors released by synovial cells. The release of joint proteoglycan may cause a temporary increase in deformability of the hip cartilage of the child that could be an important pathogenetic mechanism in some of the sequelae of these diseases.

The normal and abnormal anatomy of the hip joint in childhood was evaluated by ultrasonography (US) with reference to examination technique and errors. When compared with computed tomography (CT), it was confirmed that the two sonographic echoes from the hip joint represent the femoral neck and the external surface of the capsule and that the thickness of the echo received from the capsule depends on the frequency of the transducer. Partial volume effects may simulate or increase the sonographic appearance of hip joint effusion. The normal relationship between joint capsule and femoral neck was established.

Sonography was successfully used to diagnose an effusion in the hips of three adults with septic arthritis and four with aseptic synovitis. The effusions were confirmed by aspiration. All the patients had markedly increased intracapsular pressure which, in the extended position, exceeded the systolic blood pressure and could well compromise the blood supply to the head of femur. Aspiration reduced pain and intracapsular pressure, as did flexion of the hip to 45 degrees.

Conventional radiography was performed at diagnosis and at follow-up 5 to 9 months later in 70 children with transient synovitis of the hip. Twenty-four of the patients also had CT examination at diagnosis. The cartilaginous and osseous reaction in the conventional antero-posterior radiographs was studied as was the relation between the radiographic and CT findings concerning fat planes, joint effusion, and position of the hip joint. At diagnosis there was significant increase in the medial joint space and at follow-up examination there was significant increase in medial and cranial joint space, metaphyseal width and acetabular roof width. There was a correlation of a bulging lateral 'capsular fat plane' to the position of abduction in the affected hip which explains the asymmetry in the lateral fat plane observed in these patients.

Nineteen consecutive children with transient synovitis of the hip were examined for intracapsular joint effusion using computed tomography (CT) and ultrasonography (US). The two techniques were highly correlated in measurements of the anterior displacement of the joint capsule, indicating both to be reliable diagnostic tools. Such an effusion is clinically important because of the increase in intracapsular pressure with ensuing disturbance in the vascular supply to the proximal femoral epiphysis, as demonstrated experimentally and clinically in transient synovitis.