[Comparison of Modifications of Femoral and Tibial Lengthening in Children]. / Srovnání modifikací prolongace femuru a bérce u detí.

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.

[Correction of Valgus Knee Deformity by Hemiepiphyseodesis: a Restrospective Analysis]. / Korekce valgózní deformity kolena u detí pomocí hemiepifyzeodézy: retrospektivní analýza.

PURPOSE OF THE STUDY Hemiepiphyseodesis is commonly used to correct a coronal plane knee deformity during childhood. Since 2007 Blount staple method has been replaced by the eight-Plate Guided Growth System. We retrospectively analysed the indications, results and complications of the older Blount staple method so as to compare them with the newer eight-Plate Guided Growth system. MATERIAL AND METHODS In the period from 2009 to 2019, a total of 98 lower extremities of 54 patients were treated by hemiepiphyseodesis. Lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA) and mechanical axis deviation (MAD) were measured before and after the correction. We focused on the location of hemiepiphyseodesis (distal femur/proximal tibia/both), the operative time and compared the results of implanting 2 or 3 Blount staples. RESULTS The primary correction of valgus knee deformity was achieved in 97%, of which only partial correction was observed in 9.2% and slight overcorrection in 6.1%. A total of 4 patients (4.1%) underwent subsequent corrective osteotomy. The mean LDFA increased from 80° to 86°, while the mean MPTA decreased from 94° to 92°. The mean MAD decreased from 23 mm to 3 mm. The reported complication rate was 5.1%, including four cases of loosening of staples and one case of superficial infection. DISCUSSION It has been verified that the LDFA reduction correlates with staple implantation into the distal femur, conversely the increase in the MPTA correlated with the implantation of staples into the proximal tibia or into both locations. The number of implanted staples (2 or 3) did not affect the size of the resulting correction, but the operative time was statistically significantly shorter when 2 instead of 3 staples were implanted. CONCLUSIONS Blount staple hemiepiphyseodesis is an older method, but it still gives very good results with a low rate of complications. The operating time can be shortened by using 2 staples only, with the same correction effect. The LDFA and MPTA parameters are helpful in identifying the location of hemiepiphyseodesis. The key to success of treatment still remains in correct timing of the implantation of staples with sufficient growth potential. Key words: hemiepiphyseodesis, guided growth, valgus knee deformity, Blount staple.