Subchondral bone failure in an equine model of overload arthrosis

Gross examination of metacarpo-/metatarsophalangeal (fetlock) joints from racehorses revealed defects on the condylar surface that ranged from cartilage fibrillation and erosion to focal cartilage indentations and cavitation in subchondral bone characteristic of traumatic osteochondrosis. Because these lesions represented a spectrum of mechanically induced arthrosis in which microdamage is thought to play a role, a histologic study of sagittal sections was made to study the morphogenesis. Subchondral bone failure developed beneath a flattened section of the condyle where the margin of the sesamoid bone produces compression as well as shear on impact of the foot with the ground. Milder lesions had thickening of subchondral bone and underlying trabeculae. With advancing sclerosis an increased amount of osteocyte necrosis was present. Occasional vascular channels with plugs of matrix debris and cells were present just beneath the cartilage. There was increased prominence of subchondral vessels, and osteoclastic remodeling was seen in and around the sclerotic zone. Apparent fragmentation lines in the subchondral bone suggested increased matrix fragility. Irregular trabecular microfractures developed at a depth of a few millimeters. Increased vascularity with hemorrhage, fibrin, and fibroplasia could be seen in enlarged marrow spaces at this more advanced stage. The overlying articular cartilage was variably indented but remained largely viable with degeneration and erosion limited to the superficial layers. Focally, breaks in the calcified layer appeared to lead to collapse and cartilage infolding. In metacarpal condyles from experimental horses run on a treadmill, there were milder changes at the site. The subchondral bone was increased in volume and there was increased diffuse staining with basic fuchsin, but no increase in the number of microcracks was seen. The findings in the racehorses indicate that the equine fetlock condyle is a consistent site of overload arthrosis in which microfracture and failure in subchondral bone may occur. Controlled exercise in treadmill horses may provide a model in which to study the pathogenesis.

Destruction of the first carpometacarpal joint behaves differently from that of the entire carpus in rheumatoid arthritis. A 20-year follow-up study

The aim of our study was to examine the radiographic changes of the wrist and the first carpometacarpal (CMC I) joints in rheumatoid arthritis (RA) occurring over 20 years. The wrists of 83 RF positive RA patients with recent (< or = 6 months) arthritis were evaluated radiographically at onset, at 1, 3, 8, and 15 years and of 68 patients 20 years from entry. In hands where wrist fusion was performed, follow-up continued until the arthrodesis. Larsen grading for the wrist joints and modified grades for the ipsilateral CMC I joints were compared. Larsen grades of both wrists differed highly significantly (p < 0.001) from the grades of the ipsilateral CMC I joints after 3 years and up to end of the study. In conclusion destruction of the CMC I does not proceed uniformly with destruction of the entire carpus and it would be beneficial to classify it separately.

Recognition of sickle cell anemia in skeletal remains of children

The present study discusses in detail the osteological changes associated with sickle cell anemia in children and their importance in differential diagnosis. Posterior calcaneal and specific articular surface disruptive metacarpal lesions are diagnostic for sickle cell anemia. Calvarial thickening, tibial and femoral cortical bone thickening, and bowing are of more limited utility in differential diagnosis. Granular osteoporosis, pelvic demineralization and rib broadening are nonspecific. Localized calvarial "ballooning," previously not described, may have diagnostic significance. Bone marrow hyperplastic response (porotic hyperostosis) in sickle cell anemia produces minimal radiologic changes contrasted with that observed in thalassemia and blood loss/hemolytic phenomenon. Two other issues, the osteological criteria for discriminating among the anemias and the purported relationship between porotic hyperostosis and iron deficiency anemia, are also discussed. There is sufficient information to properly diagnose the four major groups of anemias, and further, to establish that iron deficiency is only indirectly associated with porotic hyperostosis. The hyperproliferative bone marrow response (manifest as porotic hyperostosis) to blood loss or hemolysis exhausts iron stores, resulting in secondary iron deficiency.

Hypertrophic osteoarthropathy in a blesbok (Damaliscus dorcas phillipsi)

A 4.5-yr-old female blesbok (Damaliscus dorcas phillipsi) was radiographed following the appearance of lameness and swelling of the right front fetlock. Radiographic interpretation at that time was osteoarthritis caused by periosteal proliferation of the right metacarpus with periarticular osteophytes surrounding the fetlock. No treatment was initiated. Gradual abdominal enlargement over several months was interpreted as evidence of pregnancy. Six months after the initial lameness complaint, the blesbok suddenly collapsed and was unable to stand. Physical examination revealed a large firm mass occupying most of the abdomen that was found to be inoperable. Following exploratory laporotomy, the blesbok was euthanized. At necropsy, the mass weighed 17 kg. It had probably caused the animal's collapse. Histologically, the bony lesions of the right metacarpus, seen radiographically at the previous examination, were consistent with hypertrophic osteoarthropathy and may have been a sequela of the intra-abdominal mass.

Multiple aneurysmal bone cysts in a foal

Multiple aneurysmal bone cysts (ABCs) are previously unreported in horses. An ABC was diagnosed in the left 3rd metacarpal of a Thoroughbred foal, which partially resolved following surgical curettage. A 2nd ABC developed in the left tibia, 7 wk postoperatively, and the foal was euthanized.

["Secondary" chondrosarcoma of the hand. Case report and review of the literature]

Rapid growth of a painful and often recurrent bone tumor of the hand, is suspicious of low malignant chondrosarcoma, even despite previous histological identification as an enchondroma. The difficulty of differential diagnosis of enchondroma and chondrosarcoma is demonstrated in two cases and discussed in a review of the literature.

The radiographic stage of giant cell tumor related to stromal cells' proliferation. Tissue cultures in 13 cases

The clinical behavior of giant cell tumor is related to the radiological appearance. To test the hypothesis that in vitro proliferation of the neoplastic stromal cell population of giant cell tumors is related to the radiological appearance, this study was undertaken. A prospective analysis of the cells migrating from 13 consecutive tumors was conducted. Growth curves and population doubling-times (PDT) for first and fifth passages were calculated and alkaline phosphatase levels were measured and compared to preoperative radiographic staging. A strong negative correlation was found between PDT and the radiographic stage. Tumors in stages I and II (low aggressiveness) were found to have an average cell population doubling-time of 11 (SD 2.2) days, while those in stage III (high aggressiveness) showed a doubling-time of 6 (SD 2.2) days. Low alkaline phosphatase activity was noted in all cultures, a finding consistent with the putative preosteoblastic potential of these stromal cells. This putative origin is also indicated by the differentiation response to retinoic acid. The findings suggest that the in vitro proliferation of the mononuclear stromal cell population of giant cell tumors is related to the radiographic stage and may predict the clinical behavior of these tumors.

Is anatomical reduction of fractures of the fourth and fifth metacarpals useful?

Most fractures of the fourth and fifth metacarpals are treated conservatively. How necessary it is to pursue anatomical reduction of these fractures has not been determined. In order to evaluate whether anatomical reduction will result in a better outcome, two groups of one hundred patients each, were compared. One group had been treated with near-anatomical reduction. Only partial reduction had been accomplished in a control group with similar fractures. The residual radiographic angulation of the subcapital fracture at the four-week follow-up was measured in both groups, but no significant difference could be demonstrated. In shaft fractures, however, the anatomical reduction group showed significantly less residual angulation. Only reduction of shaft fractures is worthwhile in order to achieve a better anatomical outcome.

The interaction of the zone of calcified cartilage and subchondral bone in osteoarthritis

The zone of calcified cartilage (ZCC) forms an important interface between cartilage and bone for transmitting force, attaching cartilage to bone, and limiting diffusion from bone to the deeper layers of cartilage. The height of the ZCC is a relatively constant percent of articular cartilage and the height is maintained by a balance between progression of the tidemark into the unmineralized cartilage and changing into bone by vascular invasion and bony remodeling. During its formation, the cells that form the ZCC have properties similar to the cells of the growth plate. In the adult, the ZCC becomes quiescent but not inactive. The ZCC may be reactivated in osteoarthritis and may progressively calcify the unmineralized cartilage. This might contribute to cartilage thinning which would increase the concentration of forces across the uncalcified cartilage leading to more damage. Although the subchondral bony plate remodels extensively in osteoarthritis, there is little evidence that a change in the biomechanics of the plate directly initiates the osteoarthritic process in cartilage. However, increased repair by endochondral ossification of vertical cracks in the ZCC that penetrate into the marrow space could contribute to progression via changes in the ZCC.

[Angiosarcoma of the hand. Case report]

Angiosarcoma is a very rare malignant bone tumour. The case of a 45-year-old man is presented with a primary epithelioid hemangioendothelioma in the fourth metacarpus. After radical extirpation of the tumour radiation followed. The function of the hand was fully preserved. Five years after operation the patient is free of disease.

Cortical bone resorption in osteoporosis

A study was made of 110 women: 35 healthy premenopausal, 40 healthy postmenopausal, and 35 women diagnosed as having postmenopausal osteoporosis. The postmenopausal women had similar ages and years since menopause (YSM). In all of the women, total bone mass was evaluated by dual-energy X-ray absorptiometry and metacarpal morphometry was evaluated by radiogrammetry on the second metacarpal of the nondominant hand, performed by computed radiography. An external metacarpal diameter of >/=7.4 mm was required as proof of having developed an adequate peak bone mass. The endosteal diameter, which is indicative of bone resorption in both groups of postmenopausal women, obtained in the postmenopausal groups was subtracted from the endosteal diameter obtained in the premenopausal group and the resulting figure was divided by the years since menopause to calculate the rate of cortical bone resorption/year for each group. The endosteal diameters values differed in the three groups studied (P < 0.0001): 3.2 +/- 0.7 mm in the healthy premenopausal women; 3.9 +/- 0.6 mm in the healthy postmenopausal women; and 4.7 +/- 0.5 mm in the osteoporotic postmenopausal women. The rate of cortical bone resorption was 0.068 +/- 0.002 mm/YSM (years since menopause) in the osteoporotic postmenopausal women and 0.033 +/- 0.003 mm/YSM in the healthy postmenopausal women (P < 0. 0001). These figures reflect the importance of bone resorption, as opposed to deficient bone formation, as a cause of osteoporosis.

Age-related cortical bone loss at the metacarpal

In order to evaluate in vivo the entity of endosteal and periosteal changes with age in the two sexes, and their relative contribution to age-related cortical bone loss, we undertook a cross-sectional study on a population of normal Caucasian subjects. The group included 189 women and 107 men who were studied by photodensitometry and radiogrammetry of the second metacarpal bone, derived from the same standard hand X-ray. Of the subjects, 134 were 65 years of age or older (75 women and 59 men). Metacarpal bone mineral density (BMD) correlated with age in both sexes, with an annual bone loss rate of 0.5% in women and 0.15% in men. In the over 65 group, correlation was significant only in women, who underwent an acceleration in the rate of bone loss (1% per year). Marrow cavity width (M), cortical index at the second metacarpal shaft (MI) and external width (W) all correlated with age in both sexes, although generally better in the female than in the male sex. M almost doubled from the fourth to the ninth decade in women and increased 50% in men. In the same age interval, MI showed an annual decrease of 0.49% in females and 0.33% in males. In the over 65 group, cortical thinning rate was significant in women (0.39% per annum) but not in men (0.14% per annum), whereas correlation of W was not significant in either sex. Finally, MI correlated with BMD in the whole study population and in the over 65, with a female prevalence in correlation strength maintained throughout life. The following conclusions can be derived for metacarpal aging: (1) an acceleration in cortical bone loss occurs in females after age 65; (2) age-related growth in periosteal diameter, although significant in the whole population, is negligible in the elderly of both sexes; (3) age-related cortical bone loss is generally more dependent on cortical thinning in women than in men.

[Metastasis of an adenocarcinoma of the colon to the 1st metacarpal bone]

The authors report a clinical case of metastasis to the first metacarpal arising from carcinoma of the colon, treated surgically four years previously. Clinical examination revealed painful swelling over the right thenar eminence. The diagnosis was established by radiology and needle biopsy. No treatment was administered and the patient died one month later. Metastases of the hand are uncommon and, according to the review of the international literature concerning bone metastases in the hand conducted by Kerin (1987), are usually secondary to lung, renal and breast cancers. Only a few cases have been described in the literature of bone metastases of the hand from carcinoma of the colon. The authors feel that some of these cases probably remain undiagnosed, as they are of secondary importance in view to the severity of the disease.

Investigation of bone developmental and histopathologic changes from intraosseous infusion

STUDY OBJECTIVE

To evaluate clinical and cellular changes of bone through the rapid growth phase of development after intraosseous infusion of hypertonic or isotonic solutions at slow or fast infusion rates in a pig model.

METHODS

This was a prospective, randomized, partially blinded, comparative study using a porcine model in an urban teaching hospital laboratory with further development in a local farm environment. Sixty pigs weighing 12 to 30 kg were anesthetized and endotracheally intubated, and a no. 15 Jamshidi bone marrow needle was inserted into a front forelimb. Hypertonic (mannitol) or isotonic (saline) solutions of 8 mL/kg were infused through the intraosseous site at a rapid or slow infusion rate. Animals were observed for approximately 6 months, after which they were killed and the front forelimbs harvested for gross pathologic and histologic evaluation.

RESULTS

No clinical complications were noted in any of the animal groups. No substantial histologic differences were found between the hypertonic and isotonic groups. Although gross pathologic lesions were found in 32% of the hypertonic groups and in fewer than 5% of the isotonic groups, this difference was not statistically significant. Equal bone changes were found in the slow- and rapid-infusion groups.

CONCLUSION

The rate of intraosseous infusion and the osmolarity of the infused fluid did not appear to be related to any gross pathologic or histologic cellular or marrow changes or to any clinical complications in animal development in this study.

Hypertrophic osteopathy (Marie's disease) in Equidae: a review of twenty-four cases

The case records of 23 horses and one donkey affected by hypertrophic osteopathy (HO) (Marie's disease) were reviewed. All affected animals presented with limb swellings, which were bilaterally symmetrical and usually involved both fore- and hindlimbs. Associated signs included stiffness/lameness and weight loss. Radiological features included periosteal new bone formation over the diaphyses and metaphyses of affected bones. The metacarpal and metatarsal bones were most frequently affected. Articular surfaces remained free of disease. Seventeen animals were destroyed on humane grounds, 3 horses recovered after successful treatment of the primary disease, 3 horses recovered after symptomatic treatment and one horse was lost to follow-up. Significant primary diseases that were believed to predispose to HO were identified (pre- or post mortem) in 14 cases. In each of these cases, an intrathoracic disease was identified, although co-existing extrathoracic disease was present in 3 cases. Granulomatous inflammatory lesions were present in 9 of these 14 cases. In 4 horses, which underwent necropsy examination, no significant underlying disease was identified.

Results of scaphotrapeziotrapezoid fusion for isolated idiopathic arthritis

Scaphotrapeziotrapezoid (STT) joint fusion was carried out for pain relief in eight patients with isolated arthritis. Seven patients had satisfactory relief of symptoms. The subjective results were excellent in five, good in two and bad in one patient, who had non-union of the arthrodesis and was also the only patient to develop trapeziometacarpal arthritis. Average grip strength was 0.8 and lateral pinch strength was 0.7 of that in the other hand. There was a very small relative difference in dexterity. There was an average difference of 9 degrees of flexion-extension and 13 degrees of radio-ulnar deviation. It is concluded that for isolated idiopathic STT arthritis, fusion gives very satisfactory results with minimal complications.

Rhabdomyosarcoma of the hand. Two case reports and a review of the literature

Two cases of rhabdomyosarcoma (RMS) of the hand are reported.

Giant cell tumour of metacarpal with pulmonary and skeletal metastases

A case of giant cell tumour of the left fifth metacarpal with pulmonary and skeletal metastases is reported with follow-up of 14 years. The pulmonary metastases were treated by chemotherapy, but the size of the metastatic nodules continued to increase, and no further treatment was given. The pulmonary metastatic nodules started to regress 8 years after the diagnosis without any treatment, and had disappeared after 14 years. The skeletal metastases were unchanged at the latest follow-up. Both pulmonary and skeletal metastases have been asymptomatic for the 14 years after they were diagnosed. It is suggested that pulmonary metastases of benign giant cell tumour has a good long-term prognosis and these patients should be kept under observation only, avoiding extensive lobectomy, chemotherapy or radiotherapy.

Incidence and distribution of scaphotrapezotrapezoidal arthritis in 73 fresh cadaveric wrists

The STT joint was examined in 73 fresh cadaveric specimens (25 male and 48 female with an average age of 84 years) with a view to study the incidence and characteristics of degenerative changes in this joint. The articular degeneration was graded from 0 to 3 according to increasing loss of cartilage and the location of the changes was noted. At the same time, the presence and extent of concomitant trapezio-metacarpal arthritis was noted. 61 of the 73 hands (83.3%) were found to present STT arthritis. Degeneration of the trapezoid articular surface was:- more frequent: 53 hands (72.6%) as compared to 48 (65.7%),-of greater severity: 40 cases (55%) of grades 2/3 as compared to 25 (34%), than that of the trapezium. Concomitant or isolated arthritis in the trapezometacarpal joint (90.4%) was present in 66 of the 73 hands (79%) examined with grade 3 changes in 13 cases. The apparent predominance of degeneration in the scapho trapezoidal articulation could, perhaps, lead us to assume that this might be the site of origin of STT arthritis. It could also explain the persistence of symptoms following prosthetic replacement of the trapezium.