Properties of growing trabecular ovine bone. Part I: mechanical and physical properties.

Our aim was to determine the relationship between age and the mechanical and physical properties of trabecular bone, to describe the patterns in which the variations in these properties take place, and to investigate the influence of the physical properties on the mechanical characteristics of trabecular bone during growth. We used 30 lambs in three age groups and 20 sheep in two age groups. Cubes of subchondral bone were cut from the proximal tibia according to a standardised protocol. We performed non-destructive compression tests of the specimens in three orthogonal directions and compression tests to failure in the axial direction. The physical properties of the specimens were also determined. The data were correlated with age and compared in skeletally immature and mature animals. Multiple regression analyses were performed between the mechanical and the physical properties. Age correlated positively with elastic modulus, bone strength, energy absorption to failure, elastic energy, mechanical anisotropy ratio, tissue density, apparent density, apparent ash density, and bone mineral content, and inversely with ultimate strain, viscoelastic energy absorption, relative energy loss, the collagen content of bone and the percentage porosity. The values of all variables were significantly different in the skeletally mature and immature groups. The apparent density of trabecular bone tissue was found to be the major predictor of its compressive mechanical properties. Together with the content of bone muscle and bone collagen, the apparent density could explain 84% of the variation in the elastic modulus, whereas only a small portion of the variation in ultimate strain could be explained by the variation in apparent density.

Properties of growing trabecular ovine bone. Part II: architectural and mechanical properties.

We aimed to highlight the relationship between age and the architectural properties of trabecular bone, to outline the patterns in which the variations in these properties take place, and to investigate the influence of the architecture on the mechanical properties of trabecular bone in growing animals. We studied 30 lambs in three age groups and 20 sheep in two age groups. Cubes of subchondral bone were cut from the proximal tibia according to a standardised protocol. They were serially sectioned and their architectural properties were determined. Similar cubes were obtained from the identical anatomical position of the contralateral tibia and their compressive mechanical properties measured. The values obtained from the skeletally immature and mature individuals were compared. Multiple regression analyses were performed between the architectural and the mechanical properties. The bone volume fraction, the mean trabecular volume, the architectural and the mechanical anisotropy, the elastic modulus, the bone strength, the energy absorption to failure, and the elastic energy correlated positively with increasing age whereas the connectivity density, the bone surface density, the ultimate strain, the absorption of viscoelastic energy and the relative loss of energy correlated inversely. The values of all variables were significantly different in the skeletally mature and immature groups. We determined the patterns in which the variations took place. The bone volume fraction of the trabecular bone tissue was found to be the major predictor of its compressive mechanical properties. Together with the mean trabecular volume and the bone surface density, it explained 81% of the variations in the compressive elastic modulus of specimens obtained from the contralateral tibiae.

Survivorship analysis of cemented total condylar knee arthroplasty. A long-term follow-up report on 348 cases.

Survivorship analysis was used in the evaluation of 348 consecutive primary total condylar knee arthroplasties (total knee arthroplasties) performed on 253 patients in a 27-month period, with a maximum follow-up period of 12 years. The diagnosis was osteoarthrosis in 184 cases and rheumatoid arthritis in 164 cases. Ten patients (10 total knee arthroplasties) were lost to follow-up evaluation. The endpoint was defined as prosthesis not in situ. The variables considered were age, sex, body mass index, and diagnosis. The overall cumulative survival rate was 92%. The survival rate of the osteoarthrosis group was significantly higher (97%) than that of the rheumatoid arthritis group (87%). None of the other variables affected survival rate significantly.

[Femoral shaft fractures in children. An epidemiologic study in the Greater Arhus]. / Fractura corporis femoris hos børn. Et epidemiologisk studie i Stor-Arhus 1977-1986.

In a well-defined community, 144 cases of femoral shaft fracture in children (< 15 years old) were registered over a ten-year period. The cases were analysed epidemiologically. The variables taken into consideration were age, sex, aetiology of the fracture, and yearly and seasonal changes of the incidence rates of the fracture. The boy/girl ratio was found to be 2.8:1. The incidence rate was 28 per 100,000 child-years. Young children (< three years) had the highest incidence rates. The most common aetiology was traffic trauma (43.1%), fall trauma (41.7%) coming next. Falling off bicycles contributed with 41.9%, direct trauma with 3.5%, and jamming with 5.6%. An incidence peak was found in the summer months April through August. Involvement of children in traffic accidents and the number of femoral shaft fractures due to traffic trauma fell significantly over the ten-year period.

Indomethacin for prevention of heterotopic ossification. A randomized controlled study in 41 hip arthroplasties.

The effect of indomethacin 25 mg 3 times daily during the first 2 postoperative weeks in preventing heterotopic bone formation after cemented total hip arthroplasty was investigated in a randomized, double-blind and placebo-controlled clinical trial on 57 patients. 16 patients were secondarily excluded, leaving 19 patients in the indomethacin group and 22 patients in the placebo group. Evaluated from the 3-month radiographs, 18/19 indomethacin patients developed either no or only the milder Grade 1 ossification. In contrast, 11/22 placebo patients developed Grade 2 or 3 ossifications. Our observations favor indomethacin prophylaxis for 2 weeks in cemented arthroplasty of the hip.

Total condylar arthroplasty for gonarthrosis. A prospective 10-year study of 138 primary cases.

The results of 138 consecutive primary Insall-Burstein arthroplasties with an average observation period of 10 (9-11) years were assessed. Mean age at surgery was 71 (30-81) years. The patients were evaluated clinically, using the Hospital for Special Surgery knee rating scale, and radiographically, according to the radiolucency score of the Knee Society. At latest follow-up, the overall evaluation of the patients who completed the study was excellent or good in 86 percent, fair in 8 percent and poor in 6 percent. Residual functional pain was recorded in 12 percent of cases with prostheses in situ. An ability to walk more than 500 m was found in 62 percent. The median range of motion was 104 degrees. Arthrodesis was performed on 2 knees due to deep infection. There were 14 cases with substantial radiolucency around the prosthesis, but none of these patients had severe functional pain. The crude prosthetic survival rate was 98 percent. A correlation was found between the radiolucency score and both the total score and the intensity of the residual functional pain.

Long-term results of total condylar knee arthroplasty in rheumatoid arthritis.

We have reviewed at an average period of ten years the results of 71 consecutive primary arthroplasties with the Insall-Burstein total condylar knee prosthesis in patients with rheumatoid arthritis. Their mean age at surgery was 52 years (24 to 72). At follow-up the overall results (Hospital for Special Surgery knee rating score) were excellent or good in 77%, fair in 11% and poor in 11%. There was residual pain in only 5% of patients with prostheses in situ; 58% could walk more than 500 m, and the median range of motion was 108 degrees. Eight knees had been revised. Five underwent arthrodesis because of deep infection and three needed revision arthroplasty for mechanical loosening. The crude survival rate of the arthroplasties was 89%. The presence of radiolucency around the tibial component correlated significantly with the severity of residual pain.

Femoral shaft fractures in children: an epidemiological study in a Danish urban population, 1977-86.

We report 144 femoral shaft fractures (FSF) in 138 children less than 15 years old. The boy/girl ratio was 2.8:1. The incidence rate was 28 per 100,000 child-years. Young children (less than 3 years) had the highest incidence rates. The most common etiology was trauma due to traffic accidents (43.1%) and falls (42.2%). Falling off bicycles contributed to 4.9%, direct trauma to 3.5%, and jamming to 5.6% of fractures. Involvement of children in traffic accidents and the number of FSFs due to traffic trauma fell significantly during the study period. The resource consumption of FSF was very high compared to other childhood fractures. The mean length of stay for FSF was almost three times that of all other patients seen in the emergency unit.

The press-fit Kinemax knee arthroplasty. High failure rate of non-cemented implants.

We report the results of 75 consecutive primary press-fit Kinemax arthroplasties with an average follow-up of 14 months (three to 28). We reviewed 26 cemented and 49 non-cemented tibial components implanted into 72 patients (30 men and 42 women, median age 70 years). At the latest follow-up the overall evaluation (Hospital for Special Surgery knee rating scale) for cemented cases was excellent in 54%, good in 42% and poor in 4%. No cemented prosthesis loosened. Of the non-cemented cases 55% were excellent, 23% good, and 2% fair. Ten tibial implants (20%) loosened and required revision. Residual pain marred the result in 24% of the non-cemented prostheses and in 4% of the cemented group. We do not recommend the press-fit, smooth-surfaced Kinemax prosthesis for non-cemented use.

[Long-term results of total condylar knee alloplasty by the Insall-Burstein method. A follow-up after 9-11 years]. / Langtidsresultater af totalkondyl-knaealloplastik ad modum Insall-Burstein. 9-11 års opgørelse.

A total of 118 patients (164 knees) participated in this investigation. These consisted of 23 males (31 knees) and 95 females (113 knees). The average age was 63 years (24-80 years) and the average period of observation was 10 years (9-11 years). The patients were examined clinically and radiographically preoperatively and also 8-12 weeks postoperatively and at intervals of one year thereafter. The Hospital for Special Surgery knee rating scale was employed in the clinical assessment and The Knee Society recognized radiolucency index in the radiographic assessment. At the most recent control examination, 82% of the knees assessed showed excellent or good results, 9% had fair results and 9% poor. The median total score was 84 points (quartiles: 76 and 98). Complete freedom from pain or slight pain were found in 91%. The range of motion was increased by an average of 12 degrees. A considerable improvement in the walking ability was found. A significantly positive correlation was found between the varus positioning of the tibial component and the occurrence of translucent zones. Serious complications occurred in 10% but none proved fatal.

[Playground accidents among children in greater Arhus]. / Legepladsredskabsulykker blandt børn i Storårhus.

The aim of this study was to determine the incidence rate and to determine the etiology and the severity of accidents caused by playground equipment during the period 1.1.1989-31.12.1989 and to compare the results with the study made by Christensen et al (1-3). The number of children aged below 15 years was 42,635. A total of 270 playground accidents were registered, which resulted in an incidence rate of 6.3 per 1,000 children per year. This is a reduction from 9.3 per 1,000 children per year in 1981. The incidence rates between boys and girls were 7.0 and 5.6 per 1,000 children per year, as compared with respectively. The sex ratio for the population studied was 1.31 to 1 as compared with 1.44 to 1 in 1981. The sex ratio in the background population was 1.05 both in 1981 and 1989. The greatest number of accidents were seen in spring, especially in April and May. Swings, climbing frames, slides, playhouses and playcastles were responsible for 80% of the accidents. The etiologies were fall accidents in 211 cases, being caught between two objects in 17 cases, being kit by an object in 21 cases and different causes in 21 cases. The underlying surfaces were sufficiently soft in 24% of the cases. The severity of the injury was classified according to the Abbreviated Injury Scale and was found to be: no lesions 1.1%, minor lesions 70%, moderate lesions 25.1% and severe lesions 3.7%. A total of 17 patients were admitted and of these 13 patients had fractures. The possibilities of reducing the number of injuries resulting from playground equipment are discussed.

[Complications after osteosynthesis using Partridge's method in femoral fracture near the prosthesis]. / Komplikationer efter osteosyntese a.m. Partridge af protesenaere femurfrakturer.

The object of the investigation is to illustrate the results and complications following Partridge's osteosynthesis of proximal fractures in the neighbourhood of the prosthesis. During a period of 40 months, eight consecutive patients (two men and six women) with proximal fractures of the femur in the neighbourhood of a hip prosthesis were subjected to osteosynthesis by Partridge's method. All of the fractures resulted from low energy trauma. The average age was 72 years (51-84) and the average duration of observation was 2.3 years. Weight-bearing was permitted after an average of 14.5 weeks and the radiographically assessed healing time was 16 weeks on an average. In all of the patients, cortical erosion developed under the Partridge bands 10-16 weeks postoperatively. In five patients, the initial erosions were of limited extent and were stationary during the period of observation. In three patients, the osteolysis was progressive and reoperation with introduction of a long-shafted femur prosthesis proved necessary. In addition, homologous boney transplants were necessary in two of these patients. Stability and healing of the fracture are obtained by osteosynthesis by Partridge's method but, on account of the osteolysis which is frequently pronounced and progressive, the patients should be followed-up meticulously in view of the possibility of removal of the Partridge material and possible replacement by a long-shafted femur prosthesis before the bone is completely eroded.

[Osteochondritis dissecans of the calcaneus]. / Osteochondritis dissecans af calcaneus.

We report a case of osteochondritis dissecans located to the posterior calcanear articular surface of the talocalcaneal joint. The lesion was diagnosed by radiological tomography of the joint. The treatment was surgical excision of the affected segment. The patient was still symptomfree three years later.