Microvascular obstruction in avascular necrosis. Immunohistochemistry of 14 femoral heads.

14 femoral heads with late stage avascular necrosis of different etiologies were histologically examined, with special attention to vascular structures. Decalcified slices were stained with hematoxylin-eosin, safranin-O, van Gieson stain, and Martius Scarlet Blue. Immunohistochemical techniques with antibodies against Factor VIII, and Ulex Europeus Lectin were used to visualize the endothelium of the blood vessels. 5 distinct zones of the necrotic femoral head could be identified. The necrotic zone contained areas with richly vascularized connective tissue. In the transitional zone, several areas with intravascular aggregations of newly formed and older fibrin clots were noticed, mainly on the venous side of the vascular system. Other small vessels were collapsed, with a few endothelial cells clumped together in the center of a concentric fibrous tissue. We suggest that obstruction to the venous outflow due to intravascular thrombosis as well as to perivascular fibrosis is important in the pathogenesis of non-traumatic avascular necrosis of the femoral head.

Blood perfusion uneven in femoral head osteonecrosis. Doppler flowmetry and intraosseous pressure in 12 cases.

We measured the microvascular regional perfusion in 12 hips with non-traumatic osteonecrosis of the femoral head, using laser Doppler flowmetry (LDF). Simultaneously, the intraosseous pressure (IOP) was measured in the femoral head. For comparison, the same 2 parameters were measured in 6 normal femoral heads during surgery of the contralateral hip. In osteonecrosis, the regional blood cell flux in the intertrochanteric area was 165 mV, at the rim of the lesion 430 mV, and in the necrotic lesion 35 mV. In the same areas, the IOP was 38 mmHg, 61 mmHg and 55 mmHg. In the normal hips, the LDF signal was 221 mV and 224 mV, and the IOP was 21 mmHg and 19 mmHg intertrochanterically and in the femoral head, respectively. We conclude that the microvascular blood perfusion is uneven in an osteonecrotic head.

Arthroplasty for congenital hip dislocation. Techniques for acetabular reconstruction.

We investigated a series of 63 arthroplasties for chronically dislocated hips or severe dysplasia with at least two thirds of the femoral head uncovered. Direct cementation into the neoacetabulum at the pelvic wing was followed by 6/20 revision arthroplasties and 3/20 impending failures. Cups supported by cortical bone grafts were revised in 8/16 and found loose in 2/12 arthroplasties. The best technique was restoration of the rotational center of the hip joint and roof reconstruction with a femoral head graft with 2/25 revisions and signs of loosening in 2/25.

Osteotomy of the patella in the patellofemoral pain syndrome. The significance of increased intraosseous pressure during sustained knee flexion.

In 40 patients with patellofemoral pain, intra-osseous pressure measurements were recorded under anaesthesia with the knee first in extension and then in flexion prior to performing a longitudinal osteotomy of the patella. There was a statistically significant increase of pressure in painful knees compared with normal knees (29 mm Hg. vs 15 mm Hg.), and a marked increase when compared during sustained flexion (97 mm Hg. vs 60 mm Hg.). However wide variability of individual results made the diagnostic value of a single pressure measurement unreliable. A clinical test, based on reproduction of the characteristic pain by sustained knee flexion, proved to be reliable in predicting a good response to operation. The effect of the operation was encouraging, with significant relief of pain as measured by a visual analogue scale.

Experimental osteoarthritis in the rabbit. A study of 133xenon washout rates from the synovial cavity.

Synovial perfusion in 6 rabbit knees, with experimentally induced osteoarthritis (joint instability), was studied by recording the initial 133Xe washout rates from the joint space. The unstable osteoarthritic knee was compared with the contralateral sham operated control knee at intervals of 6 to 96 weeks postoperatively. Within the first half year the ratio between the 133Xe washout rates in the osteoarthritic and control joints was significantly increased. These findings were supported by the increased blood flow to the joint region, visualized by scintigraphy of osteoarthritic rabbits given 99mTc-microspheres intracardially. However, methodological sources of error do not allow any conclusions regarding the much less increased 133Xe washout rates found in advanced osteoarthritis. The initially increased synovial blood flow coincided with the existence of joint effusion and the early development of osteophytes, all conditions supposed to be a consequence of posttraumatic synovitis. Attention is drawn to these pathogenic phenomena in studies dealing with the initial changes in experimental models of osteoarthritis and to a possible etiological significance.

Resurfacing of depression fractures of the lateral tibial condyle. A report of five cases.

Five patients with fractures of the lateral tibial condyle were treated operatively by resurfacing of the lateral tibial plateau by means of a Marmor polyethylene tibial prosthesis. The indications were persistent pain and valgus deformity. In four patients, in whom the cartilage of the lateral femoral condyle was normal at the time of operation, the results were excellent. One patient with osteoarthritic cartilage degeneration of the femoral condyle was not improved by the operation.

The effect of joint position on juxta-articular bone marrow pressure. Relation to intra-articular pressure and joint effusion--an experimental study on horses.

Six metacarpo-phalangeal joints of adult horses were studied. Pressure measurements were made in the joint and the metacarpal bone with simultaneous measurement of the systemic arterial blood pressure. Investigations performed to study the effect of joint position on juxta-articular bone marrow pressure showed that an increase in joint flexion was always followed by a rise in intraosseous pressure with a significant increase at flexion above 60 degrees. Increase in intra-articular pressure which was achieved by injection of saline was always followed by a slower rise in intraosseous pressure. Furthermore, it was shown that even a few millilitres of saline in the joint caused a rise in intra-articular pressure. The findings indicate that changes in joint position as well as effusion may block the drainage vessels from the bone marrow as they pass through the joint.

The synovial membrane in human coxathrosis: light and electron microscopic studies.

Changes of the synovium are in integral part of osteoarthritis. Most authors regard these changes as secondary to cartilage degeneration. However, synovitis is a very early feature in osteoarthritis, and increased knowledge of changes in the chemical composition of the synovia focused our attention on the histologic characteristics of osteoarthritic synovium. Light and electron microscopic studies of the synovial membrane from patients with osteoarthritis and rheumatoid arthritis of the hip joints were performed. Two distinct types of osteoarthritic synovitis were observed: an early proliferative from characterized by venous stasis with edema, free erythrocytes and hemosiderine deposits in the interstitial tissue, that suggested increased capillary permeability. In the late form, fibrous synovitis, the microscopic picture was dominated by dense fibrous tissue. Synovium from rheumatoid arthritis showed the same vascular changes as in osteoarthritis. In addition, the histologic picture was characterized by severe inflammatory changes. In osteoarthritis the signs of inflammation were moderate or absent. The development from proliferative into fibrous synovitis is probably the result of long-standing chronic venous insufficiency. The essential feature of osteoarthritic proliferative synovitis--venous stasis with increased capillary permeability--correlates well with most of the known changes in the composition of the synovial fluid.

Permeability of synovial membrane to plasma proteins in human coxarthrosis: relation to molecular size and histologic changes.

The ratios of synovial fluid concentration to serum concentration (SF/S) for 4 nonimmunoglobulin proteins were higher in osteoarthritic synovia than in normal. The difference increased with increasing molecular weight and was highly significant for the largest molecules. An almost inverse linear relationship was observed between SF/S ratios of the proteins and their molecular weight. As only slight signs of inflammation were found in the osteoarthritic synovium, no correlation could be demonstrated between ratio and the degree of synovial inflammation as assessed by histologic methods. Two types of synovitis were encountered in patients with osteoarthritis: an early "proliferative" stage, characterized by synovial edema and large numbers of dilated venules and capillaries and a later "fibrous" stage characterized by scarring of the synovium. The highest ratios corresponded to the proliferative type. The abnormal protein pattern in osteoarthritic synovia is a result of increased capillary permeability in the synovial membrane owing to capillary dilation and stasis.

Intraosseous phlebography, intraosseous pressure measurements and 99mTC-polyphosphate scintigraphy in patients with various painful conditions in the hip and knee.

Twenty-five patients with pain in the knee or hip were examined by means of bilateral intraosseous phlebography, intraosseous pressure measurements and 99mTechnetium polyphosphate scintigraphy. All patients with typical rest pain--either due to osteoarthritis or to the intraosseous engorgement-pain syndrome--showed venous stasis and increased pressure in the bone marrow near the painful joint and abnormally high uptake of the radiotracer. In patients with other types of pain this correlation was absent. The results indicate that 99mTechnetium polyphosphate scintigraphy can be used as a screening method in the diagnosis of the intraosseous engorgement-pain syndrome in patients with a typical history. However, increased isotope uptake in a joint region may be due to a variety of other causes. The identical findings with all three methods of investigation in patients with the intraosseous engorgement-pain syndrome and osteoarthritis suggest a common pathomechanism.

The significance of intraosseous pressure in normal and diseased states with special reference to the intraosseous engorgement-pain syndrome.

When investigating a patient whose main symptom is pain aggravated by activity, or rest pain in the area of the knee (and perhaps other joints as well) the intraosseous engorgement-pain syndrome should be kept in mind. This type of pain can also be present in patients with osteoarthritis. In such patients intraosseous angiography and intraosseous pressure measurement can be useful guides when deciding the type and site of treatment. As regards the knee joint, these investigations must always be made in both tibia and femur. A drainage time of 10 and more minutes after injection of 2 ml radiopaque dye in a prone patient, and retrograde filling of intramedullary veins from a metaphyseal injection is abnormal. Concomitant intraosseous pressure measurement may be useful when made under well controlled conditions. Pressure values of more than 30--40 mm of mercury above the venous pressure are probably pathological. Rest pain can successfully be treated by a simple fenestration operation.

Fracture of the femoral neck. II. Relative importance of primary vascular damage and surgical procedure for the development of necrosis of the femoral head.

The opinion is widely held that interruption of the arterial flow through the retinacular arteries to the femoral head is the main cause of avascular necrosis after fracture of the neck. In this study the state of the vascular supply to the femoral head was assessed--prior to osteosynthesis--by means of intramedullary pressure measurements in the femoral head and neck in 72 patients with medial neck fractures. The patients were followed 2 or 3 years or until avascular necrosis became evident. The relative importance of primary avascularity and surgical technique for the development of necrosis suggests that damage to the retinacular arteries may not be the single decisive factor in the pathogenesis of femoral head necrosis. Proper fracture reduction with extensive contact between the cancellous bone surfaces and stable fixation seemed to be more important, probably because they offer the best possibilities for re-establishment of transosseous blood flow across the fracture site.