Sonographic investigation of anatomical specimens of infant hip joints.

The anatomical foundations of infant hip sonography techniques are ill-defined. We investigated anatomical specimens of infant hip joints in a water bath, with Graf's and Terjesen's methods. Acetabular position was varied in defined increments, with respect to the ultrasound beam. The alpha angles and the femoral head coverage were measured. Plastic acetabular casts were sawn along the sonographic section planes, and the cut sections compared with the sonographic sections. For images to be obtained, which were analysable by the two methods, the ultrasound beam had to intersect with the acetabular inlet plane at defined angles. The acetabular notch had to be anteriorly rotated from the ultrasound beam plane by at least 20 degrees. Beam entry within a 50 degrees sector posterior to the perpendicular on the inlet plane gave analysable images. The alpha angles and femoral head coverage were much affected by coronal-plane transducer tilt. Caudad tilts were associated with lesser values, a fact that should be borne in mind in clinical ultrasound investigations.

[A long-term follow-up study of high tibial osteotomy in medial compartment osteoarthrosis].

OBJECTIVE: To observe long-term outcome of high tibial osteotomy (HTO) in treating the medial compartment osteoarthrosis of the knee. METHODS: A retrospective study was made between 1985 and 1996, of 194 patients (215 knees) who had HTO in medial compartment osteoarthritis at the Orthopaedic Hospital of Kiel University. RESULTS: One hundred and sixty-one knees were reviewed at an average follow-up of 7.5 years (range, 1.5 - 12 years). 97.3% good and excellent results up to two years postoperatively; 93.6% good and excellent results up to five years postoperatively; at over five years, 78.2% good and excellent. Nineteen (11.8%) knees had required conversion of their HTO to a total knee arthroplasty (TKA). The survive rate of HTO taking as TKA as an end point is 98.7% in 2 years; 95.0%, 5 years and 84.1%, 10 years. CONCLUSIONS: We believe that the high tibial osteotomy is one of good methods in treating the medial compartment osteoarthritis of the knee, overcorrection the femorotibial alignment is the key step of the operation. Postoperatively, there is a trend of the results to get worse with time and a part of the patients had been revised to total knee arthroplasty because of a poor result.

Modulation of vitamin d status and dietary calcium affects bone mineral density and mineral metabolism in göttingen minipigs.

Calcium and vitamin D deficiency impairs bone health and may cause rickets in children and osteomalacia in adults. Large animal models are useful to study experimental osteopathies and associated metabolic changes. We intended to modulate vitamin D status and induce nutritional osteomalacia in minipigs. The control group (n = 9) was fed a semisynthetic reference diet with 6 g calcium and 6,500 IU vitamin D3/kg and the experimental group (n = 10) the same diet but with only 2 g calcium/kg and without vitamin D. After 15 months, the deficient animals were in negative calcium balance, having lost bone mineral density significantly (means ± SEM) with -51.2 ± 14.7 mg/cm(3) in contrast to controls (-2.3 ± 11.8 mg/cm(3)), whose calcium balance remained positive. Their osteoid surface was significantly higher, typical of osteomalacia. Their plasma 25(OH)D dropped significantly from 60.1 ± 11.4 nmol/L to 15.3 ± 3.4 nmol/L within 10 months, whereas that of the control group on the reference diet rose. Urinary phosphorus excretion and plasma 1,25-dihydroxyvitamin D concentrations were significantly higher and final plasma calcium significantly lower than in controls. We conclude that the minipig is a promising large animal model to induce nutritional osteomalacia and to study the time course of hypovitaminosis D and associated functional effects.

The dimensional accuracy for preparation of the femoral cavity in HIP arthroplasty. A comparison between manual- and robot-assisted implantation of hip endoprosthesis stems in cadaver femurs.

INTRODUCTION: The aim of the study was to determine the precision of the preparation of the femoral cavity in cementless hip arthroplasty. We compared the bone-prosthesis interface after manual- and robot-assisted implantation of the stems. MATERIAL AND METHODS: After plastination the specimens were cut to slices of 2.5 mm and documented by microradiography. The interface between prosthesis and bone was measured digitally with a specially designed software. RESULTS: The manually implanted prostheses showed an average full-contact area of 60% and an average area of gaps of 40% with an average height of 0.8 mm. The robot-assisted implanted stems had a significantly higher bone-prosthesis interface area of 93% and gap areas of less than 0.2 mm depth. Destructions of the spongeous bone were seen with the manually implanted stems but not after robot-assisted implantations. There was one stem fracture during the manual preparation of a stem. Microradiographic examination showed microfractures in the region of the lesser trochanter in two femora after robot-assisted implantation CONCLUSION: The robot-assisted technique highly increased the fitting area at the bone-prosthesis interface. The main reason for the fractures might be the absence of a robot done marker for the ideal implantation height with the applied type of prosthesis.

The objective determination of compliance in treatment of adolescent idiopathic scoliosis with spinal orthoses.

STUDY DESIGN: Prospective study using a specifically developed microelectronic technology. OBJECTIVE: To establish new technical methods for the objective measurement of brace use without patient involvement. SUMMARY OF BACKGROUND DATA: Effectiveness of spinal bracing clearly depends on the compliance of the patient. For further improvement of spinal bracing, reliable data are needed concerning the brace use. Questionnaires or clinical judgment usually estimates subjectively the compliance, which ranges from 20% to 90%. So far, only 1 study with 10 patients has investigated the compliance by objective time-stamped logging in a daily life environment, showing an average brace use of 65%. METHODS: There were 9 female patients (age 14.2 years, standard deviation 1.5) with adolescent idiopathic scoliosis who took part in the study. Their thoracolumbosacral orthoses (Chêneau braces OT-Kiel, Kiel, Germany) were equipped with a specifically developed discrete data logger to record temperature at the skin-brace interface over a period of 5.4 weeks (standard deviation 3.1), at 2-minute date/time-stamped intervals. RESULTS: Brace use ranged from 4.2 to 22.4 hours per day (average 15.4 hours). Underlying the recommended bracing time of 23 hours, average compliance rate was 67.5% (range 19.0% to 97.1%). No patient reached a complete 23-hour bracing. Patients with poor compliance usually removed the brace during the daytime. The individual bracing pattern did not change over the course of an evaluation period, and the compliance can be estimated after 2 weeks. CONCLUSIONS: Long-term logging of temperature within a spinal orthosis is a reliable and simple way to measure objectively the compliance. Thus, comparison of full-time and part-time bracing is made possible on an objective basis. Furthermore, knowing the bracing pattern provides a better focus on other variables of spinal bracing, such as the force distribution within the brace. This knowledge may help to improve further the shape and effectiveness of bracing.