Long-term evaluation of blood silicon and ostecalcin in operatively treated patients with benign bone tumors using bioactive glass and autogenous bone.

In a study on 25 patients with verified benign bone tumors, bioactive glass (BG) and autogenous bone (AB) were used as bone-graft substitutes. The patients were randomized into two groups according to the filling material. Blood samples were taken both preoperatively, at 2 weeks, and 3, 8, 12, 24, and 36 months postoperatively, for evaluation of silicon concentration in blood. In the determination, direct current plasma atomic emission spectroscopy was used. No significant difference in blood silicon concentration between the BG group or the AB group could statistically be observed (p = 0.5400), and neither did the size of the bone tumor (p = 0.4259) nor the follow-up time affect the results (p = 0.2094). Concentration of osteocalcin in blood was significantly higher for large cysts (p < 0.0001). The filler material (BG or AB) did not affect the osteocalcin concentration level in blood.

Total proximal tendon avulsion of the rectus femoris muscle.

Total proximal avulsions of the quadriceps femoris muscle group are rare injuries. Between the years 2001 and 2004 five patients with a total proximal avulsion of the tendon of the rectus femoris muscle were treated surgically in Mehiläinen Hospital in Turku, Finland. The median age of the patients was 21 years (range, 19-27) and the patients were all men. There were four soccer players and one hurdler. In all cases an avulsion of the proximal tendon of the rectus femoris muscle was confirmed by MRI. All of the patients were operated on and the delay from the injury to surgery ranged from 18 to 102 days. The result of the surgical treatment was rated good in all cases. All of the patients were able to return to their pre-injury level of activity 5-10 months after surgery. The median follow-up time was 20 months (range, 9-38). Surgical treatment of a total proximal avulsion of the tendon of the rectus femoris muscle seems to result in return to the pre-injury activity level in most cases.

MR-guided core biopsies of soft tissue tumours on an open 0.23 T imager.

PURPOSE: To assess the feasibility of MR-guided soft tissue core biopsies on an open 0.23 T magnet. MATERIAL AND METHODS: Twenty-nine consecutive patients with known or suspected benign or malignant soft tissue tumours underwent MR imaging. A one-slice dynamic enhancement sequence was used to obtain an enhancement curve of the tumour. MR-guided core biopsy of the tumour was performed in the same session. RESULTS: All biopsies could be performed on an open 0.23 T magnet. Standard MR images and dynamic enhancement curves were used in deciding biopsy route and target. The MR-guided core biopsy specimens were sufficient for histopathological diagnosis in 27 of 29 cases. CONCLUSION: Open magnet configuration allows easy access to the patient and near real-time imaging guidance of soft tissue tumours. Minimally invasive MR-guided core biopsies of soft tissue tumours are feasible and help to avoid open surgical biopsies.

Dynamic contrast-enhanced MR imaging and MR-guided bone biopsy on a 0.23 T open imager.

OBJECTIVE: To assess the feasibility of MR (magnetic resonance)-guided bone biopsies. DESIGN AND PATIENTS: Thirty-six consecutive patients with known or suspected benign or malignant bone lesions underwent comprehensive MR imaging. A dynamic contrast-enhanced sequence followed by stationary T1-weighted sequences were obtained and MR-guided bone biopsy of the tumor at the site with fastest enhancement was performed using an open 0.23 T MR imager. RESULTS: All MR-guided bone biopsies samples were estimated to be sufficient by the pathologists. The biopsy specimens were diagnostic in 34 of 36 cases. CONCLUSION: MR-guided bone biopsies combined with dynamic contrast-enhanced imaging are feasible and safe for the diagnostic investigation of equivocal bone lesions.

Bone bank service in Finland. Experience of bacteriologic, serologic and clinical results of the Turku Bone Bank 1972-1995.

560 bones were harvested by The Turku Bone Bank between 1972-1995. It was started with massive allografts for bone tumor surgery, but today most are femoral heads for hip revision surgery. The increase in harvested bones nearly trebled from 1984-1989 to 1990-1995. Only 1 positive hepatitis C test was found. There were no hepatitis B or HIV positive donors. The incidence of discarding after screening was 24%, with positive bacterial growth (8%, usually Staphylococcus epidermidis) as the commonest reason. 2 massive grafts with negative cultures when harvesting were positive after thawing and resulted in deep infection. 369 allografts were transplanted. The infection rate of massive allografts for bone tumor surgery was 5/63 in 1973-1995, and 2/52 in 1985-1995. The infection rate for hip revision surgery was 3.4%. The clinical functional results correspond to those reported in larger international series.

Polymethylmethacrylate composites: disturbed bone formation at the surface of bioactive glass and hydroxyapatite.

The effects of polymethylmethacrylate on bone formation were studied alone and as composites in combination with hydroxyapatite and bioactive glass in the rabbit subchondral femur. Radiographs, histology, computer assisted histomorphometry, scanning electron microscopy and energy dispersive X-ray analysis were used for evaluation. A total of 60 cones were implanted for 3, 6 and 12 weeks. The composite cones consisted of granules of bioactive glass (S56.5P4) or hydroxyapatite embedded in polymethylmethacrylate. Pure polymethylmethacrylate cones served as controls. At the interface of the cones, bone contact was observed only when bioactive glass or hydroxyapatite was present at the cone surface. Fibrous tissue was always found at the polymethylmethacrylate-tissue interface. The osteoconductive bone formation at the surface of bioactive glass and hydroxyapatite was disturbed by polymethylmethacrylate. It seemed to resist bone formation at the interface of both bioactive glass and hydroxyapatite. However, bioactive glass was better able to withstand the detrimental effect of polymethylmethacrylate than hydroxyapatite.

Bone formation in rabbit cancellous bone defects filled with bioactive glass granules.

We examined new bone formation after filling cancellous bone defects with bioactive glass (BG) in granular form. Cylindrical defects in the trochanter area of 18 rabbit femora were filled with BG granules (diameter 600-830 microns) and compared with similar defects filled with morcellized autogenous bone. New bone formation and surface reaction of BG particles were evaluated by light microscopy, histomorphometry, and scanning electron microscopy. The chemical profile at the bone- material interface was studied by energy dispersive x-ray analysis (EDXA). In the BG group, 41, 32, and 38 percent of the defects were filled with new bone after 3, 6, and 12 weeks, respectively. The corresponding figures for the autogenous bone group were 36, 29, and 34 percent. The thickness of the reaction layer on the glass surface increased from 82 to 163 microns during the observation periods. An intimate contact without intervening soft tissue between new bone lamellae and BG granules was a constant finding. EDXA showed a chemical continuum between the granules and the new bone. No adverse reactions related to BG were observed. BG is a promising material for filling cancellous bone defects.

Massive osteoarticular knee allografts: structural changes evaluated with CT.

PURPOSE: To analyze the structural changes seen at computed tomography (CT), particularly the findings that precede insufficiency (fatigue) fractures in massive osteoarticular knee allografts. MATERIALS AND METHODS: The subchondral and cancellous bone of 12 allografts were retrospectively evaluated with repeat transaxial CT (mean follow-up, 53 months). RESULTS: Early cortical graft resorption was followed by slow thickening after 6 months. Formation of resorptive cysts increased the cortical irregularity, which leveled off after 2 years. Late remodeling was evident as a subcortical sclerotic rim, "neocortex." Initially, the cancellous graft bone showed higher attenuation than the host bone; this difference subsided gradually during the first 3 years. Four insufficiency fractures were detected after the 1st postoperative year. Poor remodeling preceded these fractures. CONCLUSION: CT effectively depicted the structural changes during allograft incorporation and was superior to plain radiography for the detection of insufficiency fractures. The use of CT for follow-up of massive osteoarticular knee allografts provides additional information concerning the readiness of the graft for weight bearing.

Bioactive glass versus hydroxylapatite in reconstruction of osteochondral defects in the rabbit.

We studied osseointegration of a bioactive glass (BG) and hydroxylapatite (HA) in rabbit femur epiphyseal and metaphyseal regions. 17 BG and 24 HA cones implanted in defects through arthrotomy were analyzed. The holes for implants were drilled through distal femur joint surfaces. The cartilage wound repaired generally by fibrous tissue. Histomorphometry showed that 61, 78, and 79 percent of BG surface was covered by bone at 3, 6, and 12 weeks, respectively. The corresponding figures for HA were 47, 67, and 78 percent. Chemical bonding between bone and implants of both types was confirmed by scanning electron microscopy (SEM) and energy-dispersive x-ray analysis (EDXA). Formation of a calcium phosphate-rich layer on the surface BG implant was demonstrated by EDXA. Our results indicate that the osseointegration rate of bioactive glass does not differ from that of hydroxylapatite.

Spinal deformity induced by radiotherapy for solid tumours in childhood: a long-term follow up study.

A group of 44 individuals were re-evaluated at a median follow up time of 19 years after radiotherapy for childhood cancer involving some part of the vertebral column. The median age at diagnosis was 2.6 years. The diagnosis included Wilms' tumour (n = 24), neuroblastoma (n = 9) and other solid tumours (n = 11). Scoliosis with or without kyphosis was the most common spinal deformity and was found in 40/44 patients. The apex of the major curvature was on the lumbar vertebral body 1-3 in 23 cases. The kyphosis and lordosis were greater in the subjects with tumour other than Wilms' (P = 0.04 both). Of the subjects restudied, 35 had detectable local soft tissue atrophy in the region of irradiation. Scoliotic deformity often enhanced cosmetic handicap/defect. Five subjects reported some symptoms related to the back; they had more severe scoliotic and kyphotic deformity (P = 0.02). Spinal abnormalities were common in these survivors, but subjective complaints were unusual.

Totally absorbable screws in fixation of subtalar extra articular arthrodesis in children with spastic neuromuscular disease: preliminary report of a randomized prospective study of fourteen arthrodeses fixed with absorbable or metallic screws.

Seven patients with spastic neuromuscular disease and severe hindfoot valgus deformity were treated by subtalar arthrodesis. Arthrodesis was performed in both feet at the same operation and fixed on one side with a self-reinforced poly-L-lactide (SR-PLLA) screw, and with a standard AO screw on the other side. The functional status state was improved, and radiographic union of the arthrodesis occurred in all feet. The radiograph showed better solid fusion in five feet treated with PLLA screws, similar fusion in both sides in one patient, and one slower fusion in the side treated initially with a PLLA screw. Totally absorbable SR-PLLA screws appear to be firm enough for fixation of subtalar extraarticular arthrodesis in children.