PURPOSE OF THE STUDY Limb lengthening has always belonged to the most complex surgical techniques in paediatric orthopaedics. In our study, we compared the results of femoral and tibial lengthening using three different surgical techniques. The presented study aimed to shorten the duration of external fixation to a minimum and to reduce the complication rate. MATERIAL AND METHODS The retrospective study compared 74 patients (38 boys, 36 girls) who had undergone stepwise progressive lengthening of the femur or tibia between the years 2007 and 2019. The most frequent indication was the proximal focal femoral deficiency (PFFD, 33 patients). The total number of lengthening procedures was 130 (femur 72, tibia 58), the follow-up period was 2-14 years. The following modifications of surgical techniques were used: (i) standard approach, i.e. corticotomy with a two-stage removal of the fixator, (ii) preventive fixation with elastic stable intramedullary nails (ESIN) and also with a two-stage removal of the fixator, and (iii) standard approach with an early removal of the external fixator and plate osteosynthesis. RESULTS The mean lengthening achieved was 56 ± 18 (27-114) mm in femur and 54 ± 16 (25-110) mm in tibia. There was no statistical difference in the lengthening achieved by different modifications. The mean duration of external fixation in femur and tibia lengthening was comparable (166 and 164 days). The complications were observed in 60% of lengthening procedures, the most frequent being the pin release or axial malalignment of the lengthening (33 cases, 25%). The patients with ESIN displayed statistically the lowest complication rate (26%), the highest complication rate was seen in children with osteosynthesis using a plate (80%). CONCLUSIONS It follows from our results that fixation with intramedullary nails in comparison with the standard approach and plate osteosynthesis helped decrease the number of complications by more than 50%. The plate osteosynthesis is indicated in patients with repeated lengthening (achondroplasia, hypochondroplasia or PFFD with pronounced shortening) since it significantly reduces the duration of external fixation. Key words: limb lengthening, femur, tibia, surgical techniques, complications.

• MeSH
• dítě MeSH
• externí fixátory MeSH
• femur chirurgie   MeSH
• kostní hřeby MeSH
• lidé MeSH
• nestejná délka dolních končetin etiologie   chirurgie   MeSH
• prodloužení kosti * metody   MeSH
• retrospektivní studie MeSH
• tibie * chirurgie   MeSH
• výsledek terapie MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH

PURPOSE OF THE STUDY The purpose of the study was to evaluate tibio-femoral rotation during a simulated squat and to investigate the relationship between the rotational position of the femur in full extension and the amount of external rotation of the femur on the tibia during flexion. MATERIAL AND METHODS Part 1: MRIs of volunteers Data on healthy knees of 10 volunteers were obtained using 2D MRI measurements. The foot and the ankle were fixed to prevent rotation and adduction/abduction movements. Sagittal MRIs of the knees have been performed in 4 positions of flexion. The amount of longitudinal rotation in each position of flexion was calculated. Part 2: Mathematical model experiment a) The model of the femur has been positioned in the 3D coordinate system in full extension and at 12.8° of internal rotation and then flexed to 90° without longitudinal rotation. The distance between the centre of the femoral head and the sagittal plane passing through the centre of the knee was then measured. b) Subsequently, the femur was flexed and rotation allowed to retain femoral head within the sagittal plane. The amount of femoral rotation was then calculated. RESULTS Part 1: In full extension the femur was on average in 12.8° of IR relative to the tibia. By 90° flexion femur rotated on average 12.2° externally. Part 2: a)From full extension to 90° flexion the femoral head moved 93.1 mm laterally from the sagittal plane. b)Between full extension and 90° flexion the femur rotated 12.8° externally, a degree which corresponds to the amount of initial internal rotation of the femur in full extension. DISCUSSION The most important finding of the presented in vivo study lies in the fact that in normal knees with tibia rotationally fixed flexion is always coupled with femoral external rotation in order to keep the femoral head in the acetabulum. This rotation is obligatory. CONCLUSIONS We have demonstrated that if the tibia is rotationally fixed, the knee flexion is possible only when accompanied by femoral external rotation to keep the femoral head in the acetabulum. A mathematical description of the experiment has been proposed, the results of which confirm the stated premise. This finding can be explained by initial internal rotation of the femur in full extension of the knee and is allowed by the shape of articulating bones and tension of soft tissues Key words: knee, terminal extension, knee rotation, knee movement, MRI, hip joint.

• MeSH
• biologické modely MeSH
• biomechanika MeSH
• femur diagnostické zobrazování   fyziologie   MeSH
• kolenní kloub diagnostické zobrazování   fyziologie   MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• rotace MeSH
• rozsah kloubních pohybů MeSH
• tibie diagnostické zobrazování   fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE OF THE STUDY The aim of this paper was to compare terminal extension in normal and anterior cruciate ligament (ACL) deficient knees, and therefore to determine the role of the ACL during this motion. MATERIAL AND METHODS Ten knees with ACL tears (7 knees with recent ACL tears, 3 knees with long-standing tears) and 10 normal contralateral knees have been examined using MRI in passive hyperextension, 20° flexion and 20° flexion with a 9 kg posteriorly directed load on the femur. Movements of the femoral condyles on the tibia were calculated using previously described methods. RESULTS 1. Under the load at 20° flexion, knees with ACL tear showed posterior femoral subluxation (equivalent to a Lachman test), chronic tears being more unstable. Contralateral normal knees were antero-posteriorly stable. In hyperextension, both femoral condyles subluxed posteriorly in ACL tears but not in normal knees. 2. In all knees with ACL tear, the lateral femoral condyle moved posteriorly from hyperextension to 20°, equating to femoral external rotation. 3. The longitudinal rotation axis during terminal extension in normal knees was medial but in ACL tears it was central causing the medial femoral condyle to move forward from hyperextension to 20°. In normal knees, the medial femoral condyle did not move antero-posteriorly from hyperextension to 20° flexion. DISCUSSION Internal rotation of the femur during terminal extension has been recognized for 150 years. The question remains: what causes the usual combination of longitudinal rotation and extension? In the current literature ACL is considered to be responsible for internal rotation of the femur during terminal extension of the knee. So far, as we are aware, the kinematics of terminal extension, including hyperextension, have not been reported after ACL tear in the living knee. CONCLUSIONS Results of this study imply that: 1. The ACL prevents anterior tibial subluxation in hyperextension. 2. The ACL does not cause rotation in terminal extension. 3. The ACL locates the axis of longitudinal rotation in terminal extension. We hope that by studying living knees with and without ACL tear we may not only clarify the nature and mechanism of rotation in terminal extension, and hence the role of the ACL, but do so in a context of direct clinical relevance. Key words: knee, terminal extension, ACL tear, axis of longitudinal rotation, antero-posterior instability, MRI.

• MeSH
• biomechanika MeSH
• dospělí MeSH
• kolenní kloub * diagnostické zobrazování   patofyziologie   MeSH
• lidé MeSH
• ligamentum cruciatum anterius patofyziologie   MeSH
• magnetická rezonanční tomografie metody   MeSH
• nestabilita kloubu * diagnóza   patofyziologie   MeSH
• poranění předního zkříženého vazu * diagnóza   patofyziologie   MeSH
• rotace MeSH
• rozsah kloubních pohybů MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH