Histopathological prevalence of subchondral insufficiency fracture of the femoral head.

OBJECTIVE: Subchondral insufficiency fracture of the femoral head (SIF) is a recently recognised cause of acute onset arthritis mostly in older women, which previously had been commonly considered either as osteonecrosis or osteoarthritis. The purpose of this study is to report the histopathological incidence of SIF using surgically removed femoral heads. METHODS: We reviewed 7718 consecutive femoral heads from 7286 patients removed over a 4-year period (2001-2004). There were 4211 women and 3507 men. The age range was from 13 to 96, average age was 60. There were 7349 hips with a preoperative clinical diagnosis of osteoarthritis and 369 with a preoperative clinical diagnosis of osteonecrosis. RESULTS: SIF was diagnosed histologically as the primary process in 501 of 7718 resected femoral heads (6.5%). The age range in these patients was from 20 to 93, with an average age of 68, in which 79% (394 hips) were over 60. They were 305 hips in women and 196 in men. The affected side was the right one in 253 hips and left in 248. The prevalence of SIF in cases with a preoperative diagnosis of osteoarthritis was 6.3% (460 of 7349), and with osteonecrosis was 11.1% (41 of 369). In all cases, callus and granulation tissue were observed histologically along the fracture line. CONCLUSIONS: In this large series of total hip replacements SIF as the cause of disease was diagnosed histologically in 6.5% of the surgically removed femoral heads.

Photographic reproduction of anatomic specimens using ultraviolet illumination.

The black-and-white photographic reproduction of the surfaces of anatomic specimens is often difficult due to the uniformity of their color and their natural translucency. The standard illumination for black-and-white gross photographs, which uses white light with a broad range of wavelengths, results in a varying penetration of light into a translucent object; therefore, it precludes a sharp focus. The problem of translucency may be largely overcome by the use of ultraviolet illumination. Ultraviolet radiation (in the range of 320-400 nm provided by black-light sources) provides a more monochromatic light with limited penetration through the surface. As a result, the rays are either reflected or absorbed, and the scatter within the tissue layers is minimal. The combination of limited penetration and more regular reflection produces a sharper focus of the returned light. Thus it provides heightened image clarity and contrast.

Insufficiency subchondral fracture of the femoral head.

The authors recently encountered a 65-year-old osteoporotic woman who had had intractable pain in the hip joint that was diagnosed clinically as osteonecrosis. She was treated by total hip replacement. Histopathologically, the most striking finding was the presence of a subchondral fracture with associated callus formation and granulation tissue along both sides of the fracture line. There was no evidence of antecedent osteonecrosis. This case was diagnosed histopathologically as insufficiency subchondral fracture of the femoral head. This is the first case report to substantiate the presence of insufficiency subchondral fracture of the femoral head by both gross and microscopic examination. Because the treatment and management of insufficiency subchondral fracture are entirely different from osteonecrosis, it is important to differentiate between these two conditions.

Tophaceous pseudogout (tumoral calcium pyrophosphate dihydrate crystal deposition disease).

Most cases of calcium deposition seen radiologically in soft tissues are caused by calcium hydroxyapatite and occur either as a complication of trauma with associated necrosis (eg, fat necrosis), generalized connective tissue diseases (eg, scleroderma), metabolic disturbances (eg, hyperparathyroidism, familial hyperphosphatemia), sarcoidosis, myeloma, or metastases. Hydroxyapatite deposits are seen at many soft tissue sites, including joint capsules, ligaments, blood vessels, dermis, etc. On the other hand, deposits of calcium pyrophosphate are seen typically in the meniscus, articular cartilage, ligamentum flavum, and intervertebral disc. They usually are punctate or linear in distribution within the meniscus or parallel to the subchondral bone end plate. We report seven cases of massive focal calcium pyrophosphate dihydrate (CPPD) crystal deposition disease (tophaceous pseudogout) that occurred in atypical locations for CPPD. The ages of the patients ranged from 31 to 86 years (average, 60.7 years). One patient was male and six were female. The temporomandibular joint was involved in three patients and the metatarsophalangeal joint of the great toe was involved in two patients. The hip joint and cervical spine were involved in one patient each. A mass or swelling with or without pain was a common symptom. None of the patients in our series had clinical or radiographic evidence of CPPD crystal deposition disease in any other joints. Roentgenograms showed calcified lesions with a granular or fluffy pattern. Histologically, the lesions showed small or large deposits of intensely basophilic calcified material containing needle shaped and rhomboid crystals with weakly positive birefringence characteristic of CPPD. Foreign body granulomatous reaction to the CPPD deposition was constantly found. Chondroid metaplasia around and in the areas of CPPD deposition was observed commonly. Some of the chondroid areas showed cellular atypia in chondrocytes suggestive of a malignant cartilage tumor. It is important to recognize this rare form of CPPD crystal deposition disease and to identify the CPPD crystals in the calcified deposits, thus avoiding the misdiagnosis of benign or malignant cartilaginous lesions.

Primary and secondary synovial chondrometaplasia: histopathologic and clinicoradiologic differences.

One hundred thirty-six cases diagnosed clinically as either synovial chondrometaplasia or osteocartilaginous loose bodies were reviewed. On the basis of the histopathologic peculiarities, the cases were grouped into two distinct categories, primary and secondary synovial chondrometaplasia, comprising 10 and 126 cases, respectively. In each group there was synovial chondrometaplasia but the histologic patterns were dissimilar. In cases of secondary synovial chondrometaplasia the initiating factors were usually obvious and the lesions were nonaggressive. Primary synovial chondrometaplasia, on the other hand, was aggressive and was associated with a high incidence of recurrence.

Topographical variations in the morphology and biochemistry of adult canine tibial plateau articular cartilage.

Topographically, there are both morphological and biochemical differences in the articular cartilage of the tibial plateau of normal adult dogs when the cartilage covered by the meniscus is compared with that more centrally placed and not covered by meniscus. Histologically, differences are present in the surface morphology, in intra- and extracellular lipid content, and in the morphology of the mineralization front. Electron microscopy shows, in the covered cartilage, variability in collagen fiber size, with evenly spaced fibers apparently randomly distributed and an orderly relationship between the proteoglycans and collagen, whereas in the uncovered area, the collagen is aggregated into bundles and appears to be dissociated in large part from the proteoglycans. The most striking feature in the biochemistry of the two regions is an increased water content in the uncovered cartilage, as compared with the covered. In addition, there is an increased amount of proteoglycans that can be extracted in the uncovered cartilage. The heterogeneity of the cartilage on the tibial plateau should be taken into account when considering both the histologic and biochemical variations found in osteoarthritic cartilage; and when reflecting on the pathogenesis of osteoarthritis.

The differential diagnosis of geodes.

Lytic lesions close to or at the articular margins are secondary to a wide range of etiologies, including osteoarthritis, rheumatoid arthritis, hemophilic arthropathy, and crystal deposition disease as well as tumor and tumor-like conditions. In many cases the features of these "cysts" are distinctive, and the purpose of this article is to outline the characteristic hallmarks in some of the more frequently encountered arthropathies.

Spontaneous osteonecrosis of the knee: the result of subchondral insufficiency fracture.

BACKGROUND: Spontaneous osteonecrosis of the knee is a superficial subchondral lesion classically seen in the medial femoral condyle; in general, it is markedly different in its clinicopathological presentation from the classic wedge-shaped subchondral osteonecrotic lesions seen in the hip, knee, and other joints. Recent reports on subchondral insufficiency fracture of the femoral head, which has marked morphological similarities with spontaneous osteonecrosis of the knee, led us to reevaluate a series of patients who had had operative treatment because of a clinical and pathological diagnosis of spontaneous osteonecrosis of the knee. METHODS: We reviewed the cases of fourteen patients who had had operative treatment of spontaneous osteonecrosis of the knee in order to reevaluate the gross and histological morphology of this lesion. The patients included eight women and six men who ranged in age from fifty-nine to eighty-eight years. In all patients, the diagnosis of spontaneous osteonecrosis of the knee had been based on clinical presentation, imaging studies, and pathological findings. The appearance of the lesion on plain radiographs was categorized into four stages, which corresponded to the gross and histological findings. In stage 1, the radiographic appearance is normal; in stage 2, a radiolucent oval area is seen subchondrally or there is slight flattening of the convexity of the condyle, or both; in stage 3, the radiolucent area is expanded and is surrounded by a sclerotic halo; and in stage 4, secondary osteoarthritic changes are apparent. RESULTS: No patient had a stage-1 lesion. Three patients, all of whom had a stage-2 lesion, were considered to have a subchondral insufficiency fracture of the medial femoral condyle. Another six patients, all of whom had a stage-3 lesion, were considered to have a subchondral fracture and associated focal osteonecrosis that was confined to the area between the fracture line and the articular surface. The remaining five patients, three of whom had a stage-3 lesion and two of whom had a stage-4 lesion, had indeterminate findings because the lesion had become detached from the condyle. CONCLUSIONS: Our histopathological findings suggest that the primary event leading to spontaneous osteonecrosis of the knee is a subchondral insufficiency fracture and that the localized osteonecrosis seen in association with this disease is the result of a fracture.

Osteonecrosis of the knee. A clinicopathological study in twenty-eight patients.

Specimens from thirty-four knees in twenty-eight patients with histologically proved osteonecrosis were reviewed. Twelve knees had the clinical diagnosis of so-called idiopathic osteonecrosis; eight, osteoarthrosis; and fourteen, rheumatoid arthritis. Pathologically, the necrosis was localized in the subchondral region of the medial femoral condyle in 67 per cent of the knees. There were pathological fracture and collapse and fragmentation of the necrotic segment leading to marked deformities in most cases. The response to necrosis consisted of histiocytic resorption of necrotic material and formation of granulation tissue and reactive new bone surrounding it. The response was relatively less prominent in the knees with degenerative joint disease and rheumatoid arthritis.

Sensitivity to metal as a possible cause of sterile loosening after cobalt-chromium total hip-replacement arthroplasty.

We explored the possibility that wear products of cobalt-chromium alloy might lead to sensitivity to metal wear products and in turn to loosening of a component of the prosthesis after total joint replacement. Twenty patients with sterile, loose McKee-Farrar hip replacements had patch tests for sensitivity to cobalt, nickel, and chromium. All tests were negative in all patients. The histological findings from surrounding tissues in seventeen patients who had reoperation showed no signs of delayed hypersensitivity. In five patients, lymphokine assays for migration inhibition factor and blastogenic factor were done. Only one assay was positive. Our findings do not support the suggestion that hypersensitivity to metal is a cause of component loosening after McKee-Farrar total hip replacement.

Metallic wear in failed titanium-alloy total hip replacements. A histological and quantitative analysis.

We conducted extensive histological examination of the tissues that were adjacent to the prosthesis in nine hips that had a failed total arthroplasty. The prostheses were composed of titanium alloy (Ti-6Al-4V) and ultra-high molecular weight polyethylene. The average time that the prosthesis had been in place in the tissue was 33.5 months (range, eleven to fifty-seven months). Seven arthroplasties were revised because of aseptic loosening and two, for infection. In eight hips cement had been used and in one (that had a porous-coated implant for fifty-two months) no cement had been utilized. Intense histiocytic and plasma-cell reaction was noted in the pseudocapsular tissue. There was copious metallic staining of the lining cells. Polyethylene debris and particles of cement with concomitant giant-cell reaction were present in five hips. Atomic absorption spectrophotometry revealed values for titanium of fifty-sic to 3700 micrograms per gram of dry tissue (average, 1047 micrograms per gram; normal, zero microgram per gram), for aluminum of 2.1 to 396 micrograms per gram (average, 115 micrograms per gram; normal, zero micrograms per gram), and for vanadium of 2.9 to 220 micrograms per gram (average, sixty-seven micrograms per gram; normal, 1.2 micrograms per gram). The highest values were found in the hip in which surgical revision was performed at fifty-seven months. The concentrations of the three elements in the soft tissues were similar to those in the metal of the prostheses. The factors to which failure was attributed were: vertical orientation of the acetabular component (five hips), poor cementing technique on the femoral side (three hips), infection (two hips), and separation of a sintered pad made of pure titanium (one hip). A femoral component that is made of titanium alloy can undergo severe wear of the surface and on the stem, where it is loose, with liberation of potentially toxic local concentrations of metal debris into the surrounding tissues. It may contribute to infection and loosening.

Juxtacortical (parosteal) osteogenic sarcoma: histological grading and prognosis.

In twenty-four cases of juxtacortical osteogenic sarcoma, three histological grades of malignancy were identified and correlated with the prognosis. The eighteen patients with Grade-I or II tumors had a significantly better prognosis than the six with Grade-III lesions. The three grades could not be distinguished roentgenographically. Grade I and II tumors, which showed a high cure rate after amputation, may be amenable to en block resection, provided the entire tumor can be removed with a good margin of uninvolved soft tissue and underlying bone. Grade-III tumors, on the other hand, had a poor prognosis despite early radical surgery.

Incidence of ankylosing hyperostosis of the spine (Forestier's disease) at autopsy.

In a series of 75 spines studied at autopsy, the authors found 21 (28%) affected by ankylosing hyperostosis. The 21 cases included three in the cervical spine, 12 in the thoracic spine, and five in the lumbar spine. One case had both thoracic and lumbar spine disease. The average age was 65 years (range, 50-90 years). The mean weight was 85 kg, which was 20 kg more than the mean weight of the nonaffected subjects. Four cases had adult onset diabetes mellitus. No other endocrine or arthritic disease was noted either clinically or at autopsy. No abnormalities of calcium or phosphorus metabolism were found. The cause of death was unrelated to their spine disease, and clinical records were devoid of any major complaints referable to the spine.

Identification of calcium oxalate deposits in bone by electron diffraction.

Oxalosis involving bone secondary to prolonged chronic renal failure and long-term dialysis occurred in a living patient. The cystalline deposit in the small fragment of bone was identified by electron diffraction.

The morphology of the calcification front in articular cartilage. Its significance in joint function.

Biochemical and histochemical studies have indicated that there is specific cellular activity in the region of the calcification front of articular cartilage implying that a regulation process takes place there. Using scanning and transmission electron microscopy and light microscopy to examine tissue sections of both undecalcified and decalcified articular cartilage in the region of the calcification front, we have looked at its morphology with particular reference to its cellular control. Our observations show that physiological calcification is an active process under cellular control and is related to the presence of extracellular membrane-bound matrix vesicles.

Age-related changes in the thickness of the calcified zone and the number of tidemarks in adult human articular cartilage.

The thickness of the calcified zone of the articular cartilage and the number of tidemarks at the junction between articular cartilage and bone has been determined in specimens from 41 femoral heads and 42 humeral heads from cadavers aged between 25 and 93. The thickness of the calcified zone decreased with age but the number of tidemarks increased, particularly over the age of 60. These observations suggest that remodelling of the bone ends occurs and that this process is accelerated with increasing age.

The prevalence and clinicopathological appearance of extension of osteonecrosis in the femoral head.

In about 50% of cases, osteonecrosis of the femoral head is known to occupy more than one site. There is controversy as to whether a single focus may increase in size. We have reviewed 606 consecutive femoral heads which had been surgically removed for osteonecrosis. Extension of osteonecrosis was observed in only two (0.3%) and was confirmed histopathologically by the enlargement of the necrotic segment beyond the repair zone formed for the primary necrosis into the adjacent, previously uninvolved bone. In both cases, the necrotic regions were wedge-shaped and occupied over 80% of the femoral head. It appears that an increase in size is extremely rare and that osteonecrosis is due to a single event. Our findings may be of value in assessing the use of joint-salvage procedures for osteonecrosis of the femoral head.

The vascularity and remodelling of subchondrial bone and calcified cartilage in adult human femoral and humeral heads. An age- and stress-related phenomenon.

A quantitative study of the vascularity and a qualitative study of the remodelling of the calcified cartilage and subchondral bone end-plate of adult human femoral and humeral heads were performed with respect to age. In the femoral head the number of vessels per unit area was found to fall 20% from adolescence until the seventh decade and in the humeral head 15% until the sixth decade. Thereafter an increase was noted in the femur but none in the humerus. More vessels were present at all ages in the more loaded areas of the articular surfaces: 25% more for the femur and 15% more for the humerus. The degree of active remodelling by endochondral ossification declined 50% from adolescence until the seventh decade in the femoral head, and 30% until the sixth decade in the humeral head, rising thereafter to levels comparable to those found at young ages. More remodeling was noted in the more loaded areas at all ages.

Size of metallic and polyethylene debris particles in failed cemented total hip replacements.

Reports of differing failure rates of total hip prostheses made of various metals prompted us to measure the size of metallic and polyethylene particulate debris around failed cemented arthroplasties. We used an isolation method, in which metallic debris was extracted from the tissues, and a non-isolation method of routine preparation for light and electron microscopy. Specimens were taken from 30 cases in which the femoral component was of titanium alloy (10), cobalt-chrome alloy (10), or stainless steel (10). The mean size of metallic particles with the isolation method was 0.8 to 1.0 microns by 1.5 to 1.8 microns. The non-isolation method gave a significantly smaller mean size of 0.3 to 0.4 microns by 0.6 to 0.7 microns. For each technique the particle sizes of the three metals were similar. The mean size of polyethylene particles was 2 to 4 microns by 8 to 13 microns. They were larger in tissue retrieved from failed titanium-alloy implants than from cobalt-chrome and stainless-steel implants. Our results suggest that factors other than the size of the metal particles, such as the constituents of the alloy, and the amount and speed of generation of debris, may be more important in the failure of hip replacements.

The tissue diagnosis of metabolic bone disease. Role of histomorphometry.

Those aspects of bone histology and histomorphometry that need to be understood by clinicians to put histomorphometry into proper perspective are presented. An increasingly important component of the histologic diagnosis of the metabolic diseases of bone is the quantification of the various histologic features as seen in undecalcified bone biopsies. This article is intended to review some of the histologic features of the metabolic diseases of bone and their corresponding histomorphometric parameters as they are used in diagnosis. The methods of obtaining both direct and derived values as well as the reporting of the results are presented in detail.