[Growth modulation through hemiepiphysiodesis : Novel surgical techniques: risks and progress]. / Kniegelenksnahe Wachstumsmodulation durch Hemiepiphysiodese : Neue Operationstechniken: Fortschritte und Risiken.

The correction of angular deformities of the lower limb is a key task in paediatric orthopaedic surgery. The growth potential of the physis can be employed for the correction of these malalignments in childhood and adolescence. Hemiepiphysiodesis (HED) is a surgical technique used for growth modulation by permanent or temporary asymmetrical arrest of the growth plate. In permanent HED, exact timing of the procedure is mandatory to achieve optimal correction. Temporary HED through tension band devices such as two-hole-plates or flexible staples has been established as the treatment of choice for growth guidance with excellent results. Implant-associated complications have been significantly reduced through implant modifications. Several experimental procedures have the potential to achieve growth modulation even without the requirement of surgical intervention.

Growth modulation in idiopathic angular knee deformities: is it predictable?

PURPOSE: To evaluate the temporal and spatial sequence of events following temporal hemiepiphysiodesis in idiopathic knee varus/valgus. METHODS: This is a retrospective multicentre study on 372 physes in 206 patients. The average rate of correction (ROC) was calculated; univariate and multivariate analysis were performed. RESULTS: In all, 92% of the femoral physes were followed for more than one year/reached skeletal maturity. Of those, 93% were corrected to a mechanical lateral distal femoral angle (mLDFA) of 85° to 89°; 2% did not, while 5% were over-corrected. A total of 92% of the tibial physes were followed for more than one year/reached skeletal maturity. Of those, 92% were corrected to a mechanical medial proximal tibial angle (mMPTA) of 85° to 89°; 2% did not, while 6% were over-corrected. Factors significantly influencing success and ROC were age, direction and magnitude of deformity. Femoral ROC was significantly faster than tibial ROC: 0.85° versus 0.78°/month, respectively (p = 0.05). Femoral valgus ROC was significantly faster than varus ROC: 0.90° versus 0.77°/month, respectively (p = 0.04). A constant was derived to calculate the amount of correction. Significant correlation was found between calculated and actual mLDFA in valgus deformity during the first year (r = 0.58 to 0.87, p < 0.01). Calculated mLDFA of varus deformity did not correlate with actual mLDFA. Significant correlation was found when calculating mMPTA correction in all deformities. CONCLUSIONS: Femur corrects faster than tibia; valgus femoral deformities are corrected faster than varus. Valgus correction in the distal femur/proximal tibia as well as varus correction in the tibia in idiopathic patients is highly predictable. The constant derived is the first tool which enables predicting and monitoring amount of correction in hemiepiphysiodesis when correcting angular deformities around the knee. LEVEL OF EVIDENCE: IV.

[Application of motorized intramedullary lengthening nails in skeletally immature patients : Indications and limitations]. / Anwendung motorisierter Verlängerungsmarknägel am wachsenden Skelett : Indikationsspektrum und Limitationen.

BACKGROUND: Limb lengthening and deformity correction with motorized intramedullary lengthening nails is a more comfortable and equally safe procedure than the use of external fixators. While this treatment is a well-established method in adults, intramedullary nailing for skeletally immature patients remains a challenge and is the focus of current clinical investigations. OBJECTIVE: Elucidation of the indications for the application of femoral and tibial lengthening nails in skeletally immature patients, presentation of essential characteristics and limitations of the treatment. MATERIAL AND METHODS: Treatment of skeletally immature patients up to 16 years old who had a lengthening nail inserted was retrospectively clinically and radiologically evaluated (2016-2018). RESULTS: A total of 60 procedures were performed on 54 patients. Mean age at the time of surgery was 13.6 years and the mean follow-up time was 10 months. Different nailing approaches were used: antegrade femoral (n = 42), retrograde femoral (n = 10) and antegrade tibial (n = 8). The average amount of lengthening was 45 mm. In 58 of the 60 cases (96.7%) the desired amount of lengthening was achieved, while 2 patients experienced complications that required interruption of the treatment. None of the patients developed growth disorders associated with the nailing approach. CONCLUSION: Different approaches for intramedullary lengthening nails can be used in children and adolescents to correct leg length discrepancy with or without concomitant deformities. The treatment is limited by the size of the available nails, the residual growth and extent of the deformity. Larger trials will be needed to further validate the application of lengthening nails in skeletally immature patients.

Guided growth: preliminary results of a multinational study of 967 physes in 537 patients.

BACKGROUND: Guided growth by tension band plating is commonly used to correct coronal plane deformity. The purpose of this study was to measure the effect and further define parameters that influence results in coronal plane deformity around the knee. METHODS: The retrospective multicentre study included data on 967 physes in 537 patients, with an average follow-up of 16 months after plate insertion. Alignment analysis was compared preoperatively and in at least two measurements postoperatively, as well as with parameters that influence the rate and amount of correction. RESULTS: Average age at plate implantation was 11.35 years (SD 3.29).Of those with femoral deformities, 85% of the patients finished the treatment and of those, 70% were corrected to standard alignment, while 14% have not yet achieved correction, and are still growing.Of those with tibial deformities, 75% of the patients finished the treatment and of those 80% were corrected to standard alignment, while 25% have not yet achieved correction and are still growing.The calculated rate of correction was 0.77°/month for the femur and 0.79°/month for the tibia.In terms of complications, the overall rate of infection was 1.48%. In three patients (0.55%) screw breakage was recorded.Factors found to significantly influence the amount of correction were age at plate implantation and direction of deformity. CONCLUSION: Temporary hemiepiphysiodesis takes the advantage of physiological physeal growth to effectively treat angular deformities. Success of treatment is influenced by the age of the patient at plate implantation and direction of deformity. LEVEL OF EVIDENCE: IV.

Evaluation of the SMALL nail: Drive technology and behavior in situ.

Although clear advances have been made during the last 5 years, practical difficulties persist for patients and surgeons in procedures for intramedullary lengthening of long bones. In particular, precise adjustment of the desired amount of lengthening and technically reliable checking of the length actually achieved are problematic. An intramedullary nail with a new type of drive that exploits the shape memory effect has been constructed. The drive technology and the behavior of the intramedullary nail in situ were evaluated in a cadaver experiment. Three shape memory alloy limb lengthening (SMALL) nails were implanted in a body donor. The SMALL nail contains a spring coupled to a shape memory element consisting of a nickel-titanium alloy. This shape memory element "remembers" its initial state before the lengthening through the spring and can return to it when it is warmed. A cartridge heater inside the lengthening nail is warmed using transcutaneous induction with high-frequency energy via a subcutaneously implanted coil. For evaluation, two SMALL nails were implanted into the femora (antegrade on the left and retrograde on the right) and one SMALL nail was implanted into the left tibia. Lengthening by 50mm was attempted using repeated activation of the drive mechanism. At the same time, test parameters for temperature increases and cooling periods were continually monitored and the data were subsequently analyzed. The nail's mechanism worked in principle, but was inadequate in view of success rates (number of lengthening steps attempted versus number of lengthening steps achieved) of 21% for the SMALL nail in the tibia and left femur and 14% for the nail in the right femur. The temperature values measured during the distraction experiments show that high-frequency energy induction in the SMALL nail gives no cause for concern for patients.

[Special topics in pediatric orthopedics: options and limits of growth guidance]. / Spezielle Themen der Kinderorthopädie : Möglichkeiten und Grenzen der Wachstumslenkung.

BACKGROUND: A main task of pediatric orthopedics is the treatment of legs of different lengths or misshapen legs. Whereas for adult patients complicated and invasive operative interventions are necessary, the growth potential of the epiphysial plate can be utilized in childhood and adolescence to correct leg length differences and leg axis deformities. THERAPY: Epiphysiodesis leads to a guidance of growth via a temporary or permanent and partial or complete blockade of the epiphysial plate depending on the indications. This method is principally a less invasive procedure with few complications. CONCLUSION: Careful preoperative assessment of the indications and planning, precise operative technique and attentive postoperative control investigations are absolutely essential for successful treatment.

[Guided growth in children and adolescents. Correction of leg length discrepancies and leg axis deformities]. / Wachstumslenkung bei Kindern und Jugendlichen. Korrektur von Beinlängendifferenzen und Beinachsendeformitäten.

The treatment of crooked legs and unequal leg length is one of the key tasks of orthopedic surgery. While mature patients usually require complex and invasive surgical interventions, the growth potential of the physes can be used to advantage for correction of these leg length discrepancies and axis deformities of the legs in growing children and adolescents. This guided growth is induced by temporary or permanent and partial or complete arrest of the growth plate, depending on the indications. This technique is called epiphysiodesis. Although these procedures are principally less invasive with few complications, accurate preoperative indications and planning, precise surgical techniques and careful postoperative follow-up examinations are mandatory prerequisites to achieve the desired therapeutic target.

[Spectrum of indications for intramedullary or external fixators for axis correction and limb lengthening]. / Indikationsspektrum intramedullärer oder fixateurgebundener Achskorrekturen und Extremitätenverlängerungen.

Corrective osteotomy is a well established operative option for correction of predominantly congenital skeletal deformities on the growing skeleton. The indications for the use of a suitable corrective instrument result partly from the location, severity of the deformity and the presence of concomitant leg length discrepancies. External fixators are predominantly used for correction of combined deformities. For isolated leg length differences limb lengthening nails can be implanted but only after growth plates have become closed; however, only a few combined deformities can be addressed in this way. Often several surgical steps are necessary. A careful treatment plan can only be created if the analysis of the deformity is carried out with appropriate parameters and a correct prognosis of the further development. The aim of this paper is to describe the indications for the corrective instruments, the planning of corrections and the presentation of typical indications for axis correction and limb lengthening.

Walking ability of children with a hexapod external ring fixator (TSF®) and foot plate mounting at the lower leg.

Wearing an external fixator for several months can be expected to profoundly affect the ability to walk, but, in principle, full weight-bearing is possible during corrective procedures with the Taylor Spatial Frame (TSF). The present prospective cohort study was conducted to assess whether patients are able to walk with or without crutches during treatment with a TSF on the lower leg. Twenty-four patients (10 girls, 14 boys; average age 11 years, range 6-17) scheduled for fixator surgery with osteotomies in the lower leg and foot mounting were included. Dynamic foot loading during free walking was measured with plantar pressure measurements. The contact area, contact time and contact pressure on the foot plate were recorded and normalized to body weight. In the first postoperative week, all patients needed crutches and 67% showed partial weight-bearing. At the second measurement, about 6 weeks after surgery, 21% of the patients could walk without crutches and 58% were partially weight-bearing with crutches. On the day before fixator removal, 50% of the patients were fully weight-bearing without crutches and 38% were partially weight-bearing, but 12% could not bear any weight or were unable to walk. When a ring fixator is used to correct lower leg deformity and prevent equinus, there is minimal risk of complete dependence and abasia. This study shows that up to 88% of the pediatric patients are able to walk while wearing the fixator. Already a few days after surgery, two-thirds of the patients were partially weight-bearing with crutches, and only 12% needed a wheelchair and were not able to walk with the fixator.

Intramedullary limb lengthening with the Intramedullary Skeletal Kinetic Distractor in the lower limb.

We report the results of intramedullary leg lengthening conducted between 2002 and 2009 using the Intramedullary Skeletal Kinetic Distractor in 69 unilateral lengthenings involving 58 femora and 11 tibiae. We identified difficulties that occurred during the treatment and assessed whether they were specifically due to the implant or independent of it. Paley's classification for evaluating problems, obstacles and complications with external fixators was adopted, and implant-specific difficulties were continuously noted. There were seven failures requiring premature removal of the device, in four due to nail breakage and three for other reasons, and five unsuccessful outcomes after completion of the lengthening. In all, 116 difficulties were noted in 45 patients, with only 24 having problem-free courses. In addition to the difficulties arising from the use of external fixators, there were almost the same number again of implant-specific difficulties. Nevertheless, successful femoral lengthening was achieved in 52 of the 58 patients (90%). However, successful tibial lengthening was only achieved in five of 11 patients (45%).

[Pedicle screw augmentation from a biomechanical perspective]. / Pedikelschraubenaugmentation aus biomechanischer Sicht.

Severe osteoporosis is a serious problem in the instrumentation during spine surgery. Besides kyphosis, adjacent vertebral fractures and of course pedicle screw loosening and implant pullout are frequent challenges in instrumentation of the osteoporotic spine. In addition to screw diameter and length, bone mineral density has the most important impact on the stability of a pedicle screw. In cases of severe osteoporosis cement augmentation increases the stability of a pedicle screw. Pullout force can be increased with augmentation by 96-278%. Nowadays, there are two different procedures for augmentation: cement augmentation of the vertebra before inserting the screw into the soft, fresh cement or augmentation via a perforated screw that has already been inserted.The main problem in augmentation techniques are cement leakages. In both techniques leakages may occur. The problem of leakages seems to be less severe in the augmentation technique via the perforated screw, because cement application can be stopped immediately if the onset of leakage is noticed. Even surgical revision of cement augmented screws is not a major clinical problem based on recent biomechanical studies. The revision screw can be chosen 1 mm thicker and can be cement augmented again without technical problems.

Physical activity levels after limb salvage surgery are not related to clinical scores-objective activity assessment in 22 patients after malignant bone tumor treatment with modular prostheses.

BACKGROUND: The aim of the present study was to objectively assess the physical activity levels of patients after tumor prosthesis implantation with two objective measurement devices. METHODS: The DynaPort ADL monitor permitted up to 24 hr monitoring of lower-extremity physical activities in daily life with respect to posture and locomotion. The step activity monitor (SAM) was worn for a whole week to collect the daily number of gait cycles. The devices were worn during the waking hours by 22 patients with knee prostheses after wide tumor resection. RESULTS: In the MSTS and TESS scores the patients achieved over 80% of the maximum score indicating a good clinical outcome. The most prominent activity was sitting which accounted for 54 +/- 18% of the recorded time, followed by standing (27 +/- 16%), locomotion (10 +/- 6%), and lying (8 +/- 6%). During locomotion, the average walking activity accumulated to 4,786 +/- 1,770 step cycles per day (range 2,045-8,135) corresponding to a yearly 1.75 million steps. There was no significant correlation between clinical scores and step count measures. CONCLUSIONS: Even though this activity level was lower than for a group of healthy adults it was comparable to the activity level for other patients, for example, with hip arthroplasty as reported in the literature.

[Treatment of acute and chronic osteomyelitis in children]. / Behandlung von akuter und chronischer Osteomyelitis im Kindesalter.

AIM: Different studies in the past have reported about the treatment of osteomyelitis. None of these analysed the long-term results and complications after surgical treatment of acute and chronic osteomyelitis. The aim of this study was to analyse the recurrence rate and sequelae of osteomyelitis patients. PATIENTS AND METHODS: We analysed 53 children who were treated surgically between 1992 and 2004 for acute (n = 13) and chronic (n = 40) osteomyelitis. The histopathology was used for differentiation. With an average follow-up of 7.1 years (2 - 12.5 years) we examined the recurrence rate and the medical condition. RESULTS: A causative organism was identified in 53.9 % of the children with acute (AOM) and in 17.5 % of the children with chronic osteomyelitis (COM). In most cases Staphylococcus aureus could be isolated. Local antibiotics were applied intraoperatively to 92.3 % of the children with AOM and to 90 % of the children with COM. Additionally, the children with AOM were treated for 56.7 days (14 - 104 days) and the children with COM for 49.1 days (6 - 130 days) with parenteral/oral antibiotics. 2 (15.4 %) children with AOM and 6 (15 %) children with COM had a recurrence. At the time of the last examination all children were free of recurrence. One of the patients with AOM had a painless motion deficit of the shoulder. 5 children with COM complained of either pain and reduced range of motion of the affected extremity or minor deformities. CONCLUSION: Infantile osteomyelitis requires a selective diagnostic approach and an immediate parental antibiosis. If the antibiotic treatment fails, abscesses or sequestra are formed, an operation is indicated. With an adequate multidisciplinary cooperation, recurrence and sequelae can be avoided.

[Fibrous dysplasia]. / Fibröse Dysplasie.

Fibrous dysplasia is a tumorlike, benign lesion, caused by sporadic mutation during early embryogenesis. The skeletal involvement becomes increasingly visible during growth. The number and extent of dysplastic lesions increase until the age of 15. The polyostotic form is often associated with endocrine dysfunction, which should be diagnosed and treated early. Malignant transformation of fibrous dysplastic lesions is less than 1%; therefore, treatment or resection of the lesion itself is not necessary. The progress of the lesions during growth can lead to pain, fractures, and deformities. Bisphosphonates are effective for pain relief, but have no assured effect on the natural history of the disease. Fracture healing is not compromised by the disease. Conservative treatment with casts is therefore effective, especially for the upper limbs. The surgical approach with deformity correction and stabilization remains challenging particularly with regard to the proximal femur. Intramedullary devices should be preferred to plates, if possible.

[Is there a need of an additional extramedullary fixation in transverse subtrochanteric shortening in primary total hip arthroplasty for patients with severe hip dysplasia? Short-term experience in seven patients with congenital dislocation]. / Erfordert die transverse Osteotomie bei der subtrochantären Femurverkürzungsosteotomie in der Hüftprothesenimplantation hoher Dysplasiekoxarthrosen eine additive Osteosynthese? Kurzfristige Erfahrung bei 7 Hüften mit kongenitaler Luxation.

AIM: Total hip arthroplasty for high developmental hip dislocations should restore the anatomic hip centre by implanting the acetabular cup in the true acetabulum. The normalisation of the position of the hip may require femoral shortening to avoid the risk of neurological traction injury. In this study group a subtrochanteric transverse shortening with a cement-free stem (Alloclassic-SL) with a rectangular square diameter was used to secure rotation stability. METHOD: With this technique seven primary hip arthroplasties were performed in Crowe grade types III and IV. The age at time of operation averaged 41.7 years (range: 29 to 64 years). Average follow-up was 18 months. An average subtrochanteric resection of 4.2 cm (range: 3 to 5 cm) by a transverse subtrochanteric osteotomy without external fixation was performed. RESULT: There was one symptomatic stem loosening 15 months postoperatively. The average Harris hip score preoperatively of 43 points (range: 29 to 61 points) improved to a mean of 77 points (range: 66 to 90 points) at the time of follow-up. The hemispherical cups were implanted in all cases at the place of the original acetabular site. Meanwhile, there was no loosening on the acetabular side. All transverse osteotomies healed with evidence of union at the osteotomy site. At the last follow-up six of the seven Alloclassic-SL stems presented a secondary osseointegration. CONCLUSION: The subtrochanteric transverse shortening osteotomy in total hip arthroplasty is a safe and predictable method for restoring the anatomic centre in high development hip dislocation. The intramedullary stability will be secured by the distal rotation stability of the inherent cross-sectional geometry of this stem design without external stabilisation. A Z-shaped osteotomy of the subtrochanteric shortening or additional augmentation with allograft struts and cables is not necessary.

[Minimally invasive treatment of osteoid osteoma with CT-guided radiofrequency ablation in long-term follow-up]. / Die minimalinvasive Therapie beim Osteoidosteom mittels CT-gesteuerter Thermokoagulation im Langzeitverlauf.

AIM: We treated 74 patients with symptomatic osteoid osteoma by CT-guided radiofrequency ablation (CT-RF) and investigated the rate of success and complications. PATIENTS AND METHODS: 74 patients were treated by CT-RF between March 1997 and August 2001. The nidus was first located by thin-cut CT sections and then penetrated by a 2 mm coaxial drill or an 11-gauge Jamshidi needle followed by insertion of the RF probe and heat application for a period of 4-6 minutes at 90 degrees C. We investigated the recurrence of pain, complications, hospital stay, duration of postoperative pain and function. RESULTS: Nine recurrences occurred after the initial procedure, and one after a second CT-RF (rate of primary success 87.8 %, rate of secondary success 88.8 %; 98.6 % success rate in all). There was one minor complication in one case. CONCLUSIONS: CT-guided RF ablation cured 73 of 74 patients (98.6 %). It is a safe, simple, cost effective and minimally invasive treatment, which has stood the test of a long-term follow-up and we suggest it to be the treatment of choice in most cases.

[Corrective osteotomy of the humerus using perivascular axillary anesthesia according to Weber in a patient suffering from McCune-Albright syndrome]. / Oberarmkorrekturosteotomie bei einem Patienten mit McCune-Albright-Syndrom unter perivaskulärer axillärer Plexusanästhesie nach Weber.

We report on a 20-year-old patient with McCune-Albright syndrome suffering from global respiratory insufficiency who required continuous mask ventilation and where intubation had to be avoided. Perivascular axillary anesthesia according to Weber was performed for a double corrective osteotomy of the humerus. During plexus anesthesia the patient was positioned on the non-anesthesized side in a 15 degrees Trendelenburg position. An extension of analgesia was observed up to the complete upper arm region. Using the modified positioning an extension of brachial plexus anesthesia is possible.

Surgical treatment of symptomatic osteochondroma. A three- to eight-year follow-up study.

Our aim was to investigate the outcome of excision ofosteochondromas. Between 1994 and 1998, 92 symptomatic osteochondromas in 86 patients were excised. There were 40 women and 46 men with a mean age of 20 years (3 to 62). Of these, 56 had a solitary osteochondroma and 30 had multiple hereditary tumours. The presenting symptoms were pain (79.1%), swelling (23.3%), reduced range of movement (19.8%), cosmetic abnormalities (17.4%), and bursitis (12.8%). The most common site (37.6%) was around the knee. Four patients had major complications (4.7%) including one intra-operative fracture of the femoral neck and three nerve palsies which resolved after decompression. Six patients had minor complications. Overall, 93.4% of the preoperative symptoms resolved after excision of the tumours. Excision is a successful form of treatment for symptomatic osteochondromas with a low morbidity.

Tumors of the pelvis: complications after reconstruction.

INTRODUCTION: Complications after pelvic sarcoma surgery are frequent; however, the reports on complications are limited. Results of the authors' experience with 110 primary pelvic tumor resections and methods to achieve low complication rates for pelvic reconstruction are reported. MATERIALS AND METHODS: From 1982 to 1996, 110 patients with pelvic sarcoma (42 Ewing sarcomas, 40 chondrosarcomas, 21 osteosarcomas, and 7 other malignant tumors) underwent surgery. Sixteen patients underwent implantation of a hemipelvic megaprosthesis, 13 patients had implantation of an allograft for sacroiliac arthrodesis, 12 patients had implantation of an autograft for sacroiliac arthrodesis, and 17 patients underwent hip transposition. There were 9 hindquarter amputations, 6 implantations of allograft and total hip endoprosthesis, 1 implantation of prosthesis with autograft, and 1 implantation of allograft and autograft. No skeletal reconstruction was done in 35 patients. RESULTS: Postoperative function was as follows: 37% in patients with prosthesis, 60% in allograft, 66% in autograft, 66% in hip transposition, 37% in amputation, and 79% without reconstruction. In total, 10/16 patients with prosthetic replacement, 9/13 with allograft implantation, 4/12 with autograft implantation, 7/17 with hip transposition, 5/9 with amputation, 6/6 with prosthesis and allograft, and 12/35 without skeletal reconstruction had complications. Frequent complications depending on the reconstruction were infection in 6/10 prostheses and in 5/13 allografts, leg length discrepancy in 2/12 autografts and 4/17 hip transpositions, hematoma in 3/9 amputations, and infection (6) and skin problems (5) in 6 prostheses with allograft. CONCLUSION: Because of the small number of complications and good function, autograft implantation after iliac resection and hip transposition after acetabular resection are advisable.

[Correction of deformities with conventional and hexapod frames--comparison of methods]. / Deformitätenkorrektur mit Ringfixateuren und Hexapoden--Ein Methodenvergleich.

AIM: Distraction osteogenesis for the correction of deformities with an external fixator is well established. The hexapod principle of robotic technique was invented for the Ilisarov apparatus (e. g. Taylor-Spatial-Frame/TSF). Treatment with conventional frames needs a patient-customised frame mounting. This demanding procedure is markedly reduced using this technology. The aim of this study was to analyse the value of the hexapod principle in external fixation. METHOD: The potential of a frame to correct deformities is limited by its work space. The geometry of a conventional frame is different from the geometry of a hexapod frame, which is the reason for their different work spaces. The work space of the hexapod frame is compared to the work space of a conventional frame. Important parameters for this analyses are minimal and maximal frame heights and the potential of correction. RESULTS: The minimal frame height of hexapod fixators is higher compared to conventional Ilisarov fixators. The standard hexapod frame (TSF 155 mm ring diameter) can correct 23 degrees of angulation, 36 mm of shortening, 71 mm of translation and 43 degrees of rotation without changing the telescope rods. The standard conventional frame (160 mm ring diameter) can correct 90 degrees of angulation, 100 mm of shortening, 25 mm of translation and 12.5 degrees of rotation without remounting of the frame. CONCLUSION: The different work spaces of the different frames result in consequences for their clinical application. The hexapod frame has more power to correct translation and rotational deformities than a conventional frame. Correction of extensive angulation and shortening deformities almost always needs an exchange of telescopic rods. Conventional frames are usually able to correct these deformities with the primary mounting. Because of its increased minimal frame height, the indication for hexapod constructs in child orthopaedics can be limited.