Knee arthroscopy in children and adolescents.

We report a series of 77 skeletally immature patients (41 children aged < or = 13 years and 36 adolescents aged 14-16 years) who underwent knee arthroscopy. The purpose of the study was to assess the accuracy of clinical diagnosis and the value of arthroscopy. The correlation between clinical and arthroscopic diagnoses was analyzed in 54 patients. Arthroscopy confirmed the clinical diagnosis in 46.29% (25) of the patients. The accuracy of clinical diagnosis in patients aged 13 years and younger was 31.25%, whereas the accuracy in patients aged from 14 years to 16 years was 68.18%. Paediatric knee arthroscopy is a safe procedure that significantly improves the accuracy of clinical diagnosis, allows the definitive treatment of a variety of conditions and often prevents an unnecessary arthrotomy.

Biomechanical evaluation of hip joint after Salter innominate osteotomy: a long-term follow-up study.

The biomechanical state of the hip after a Salter innominate osteotomy was investigated by using the radiographic data of 38 operated and 21 contralateral nonoperated hips from our archives. The centre-edge angle of Wiberg was determined from the radiographs taken shortly after the operation. From the radiographs of the latest follow-up (7-13 years after the operation), we also determined the peak value of contact hip joint stress normalized by the body weight, and the functional angle of the weight-bearing area. A mathematical model was used. We show that the geometrical parameters aside from the centre-edge angle may considerably influence the contact hip stress distribution. We also show that the functional angle of the weight-bearing area is a more relevant parameter than the normalized peak stress if the exact magnification of the images is not known and if there is considerable variation of the image size within the sample. The development of the centre-edge angle of the operated hips and of the contralateral hips was also studied. We found that the centre-edge angle increases on average during the follow-up time in the operated hips as well as in the contralateral nonoperated hips, but the average increase is smaller in the former. It is shown that an unfavorable stress distribution is connected to the decrease of the centre-edge angle over time. Finally, we found a weak positive correlation between the centre-edge angle shortly after the operation and the functional angle of the weight-bearing area at the of the latest follow-up.

The effect of electrostimulation and high load exercises in patients with patellofemoral joint dysfunction. A preliminary report.

Traditional conservative treatment for patellar disorders is successful in about 80 percents of cases. We introduced two new conservative treatment protocols for patellar pathology in order to further improve the success rate. The first protocol consisted of high load/low repetition quadriceps femoris training (10 patients) while the second enclosed selective electrostimulation of vastus medialis muscle (7 patients). Results were evaluated clinically and neurophysiologically. High load/low repetition training resulted in significant increase of maximal voluntary contraction of quadriceps muscle (P < 0.001). Significant gain of Activity (P = 0.017) and Kujala scores (P = 0.07) was observed in group with high load/low repetition quadriceps training compared to patients with electrostimulation. There was no significant change in neurophysiological or clinical status between the beginning and the end of treatment with electrostimulation. Our results indicate that high load/low repetition quadriceps femoris training poses an important alternative to traditional conservative treatment protocol for patellar disorders.

The assessment of contact stress in the hip joint after operative treatment for severe slipped capital femoral epiphysis.

We determined contact stress on the articular surface of the hip joint in a group of patients who underwent operative treatment for severe slipped capital femoral epiphysis. Two different procedures were considered: the modified osteotomy of Dunn-Fish and the osteotomy of Imhäuser. In order to determine the stress distribution, a three-dimensional mathematical model was used taking into account the geometrical parameters of the pelvis and hip, which were measured from standard antero-posterior radiographs. We found that the Dunn-Fish procedure produced lower peak stress than the Imhäuser procedure.

Measurements of cardiac output of an isolated heart using a specially designed turbine.

Cardiac output is one of the important parameters used in evaluation of heart function. A turbine which works on mechanical principles was designed. It is also suitable for cardiac output measurements on isolated pig hearts in cases where some other equipment is not, like on doppler effect based transducers. The basic principle of measuring liquid flow through a turbine is based on measurement of the time that elapses when the rotor rotates by one degree. For this purpose, the rotor is fitted with transparent foil with a ring of 360 short black lines printed close to its circumference. Two infrared light-emitting diodes are mounted on one side of the foil and two photo-transistors, used as sensors of the transmitted infrared light, are mounted on the other. Voltage-regulated output ranging from 0 to +/- 2048 V at one revolution per second gives 500 mV at the output (changeable by programming), calculating time 2 ms, 1 mV resolution (11 bits), with an external power supply of 5 V. The turbine showed a linear response at a continuous saline flow up to 3000 ml min-1 at pressure loads of between 20 and 220 cm H2O. Pressure drop across the turbine depends on the volume flow and was 1 mm Hg at 100 ml min-1 and 3 mm Hg at 7000 ml min-1. A rotating movement 1.25 x 10(-4) kg m2 s-1 was calculated. The lowest volume change of a bolus of saline solution, detected by the turbine, was 1.6 ml.

Biochemical aspects of Salter's osteotomy for treatment of acetabular dysplasia.

The center-edge (CE) angle was measured on serial antero-posterior radiographs of 44 hips treated by Salter's innominate osteotomy for developmental dysplasia of the hip. Radiographic examination according to Severin was performed and the peak hip joint pressure was calculated using geometrical parameters determined from radiographs at the most recent follow-up examination, 7 to 13 years postoperatively. At the latest follow-up assessment, there was a positive correlation between the postoperative CE angle and radiographic results. Negative correlation was found between the postoperative CE angle and peak hip joint pressure at the latest follow up. In conclusion, Salter's osteotomy performed to treat developmental dysplasia of the hip should involve radical acetabular correction resulting in maximum increase of the CE angle.

Different operative treatment of slipped capital femoral epiphysis: a comparative study of biomechanical status of the hip.

The biomechanical status of the hips subject to two different operative treatments was studied. The biomechanical status was determined by the peak stress on the weight bearing area using the 3-d mathematical model. It was found that the procedure according to Imhäuser yields considerably and statistically significantly higher peak stress than the procedure according to Dunn-Fish.