Magnetically driven antegrade intramedullary lengthening nails for tibial lengthening.

Aims: As an alternative to external fixators, intramedullary lengthening nails (ILNs) can be employed for distraction osteogenesis. While previous studies have demonstrated that typical complications of external devices, such as soft-tissue tethering, and pin site infection can be avoided with ILNs, there is a lack of studies that exclusively investigated tibial distraction osteogenesis with motorized ILNs inserted via an antegrade approach. Methods: A total of 58 patients (median age 17 years (interquartile range (IQR) 15 to 21)) treated by unilateral tibial distraction osteogenesis for a median leg length discrepancy of 41 mm (IQR 34 to 53), and nine patients with disproportionate short stature treated by bilateral simultaneous tibial distraction osteogenesis, with magnetically controlled motorized ILNs inserted via an antegrade approach, were retrospectively analyzed. The median follow-up was 37 months (IQR 30 to 51). Outcome measurements were accuracy, precision, reliability, bone healing, complications, and patient-reported outcome assessed by the Limb Deformity-Scoliosis Research Society Score (LD-SRS-30). Results: A median tibial distraction of 44 mm (IQR 31 to 49) was achieved with a mean distraction index of 0.5 mm/day (standard deviation 0.13) and median consolidation index of 41.2 days/cm (IQR 34 to 51). Accuracy, precision, and reliability were 91%, 92%, and 97%, respectively. New temporary range of motion limitations occurred in 51% of segments (34/67). Distraction-related equinus deformity treated by Achilles tendon lengthening was the most common major complication recorded in 16% of segments (11/67). In 95% of patients (55/58) the distraction goal was achieved with 42% unplanned additional interventions per segment (28/67). The median postoperative LD-SRS-30 score was 4.0 (IQR 3.6 to 4.3). Conclusion: Tibial distraction osteogenesis using motorized ILNs inserted via an antegrade approach appears to be a reliable and precise procedure. Temporary joint stiffness of the knee or ankle should be expected in up to every second patient. A high rate and wide range of complications of variable severity should be anticipated.

Evaluation of simultaneous bilateral femoral distraction osteogenesis with antegrade intramedullary lengthening nails in achondroplasia with rhizomelic short stature: a retrospective study of 15 patients with a minimum follow-up of 2 years.

BACKGROUND AND PURPOSE: Bilateral femoral distraction osteogenesis in patients with achondroplasia is insufficiently reported. We aimed to perform the first study that exclusively analyzed simultaneous bilateral femoral distraction osteogenesis with motorized intramedullary lengthening nails via an antegrade approach in patients with achondroplasia focused on reliability, accuracy, precision, and the evolving complications. PATIENTS AND METHODS: In this retrospective singlecenter study we analyzed patients with achondroplasia who underwent simultaneous bilateral femoral lengthening with antegrade intramedullary lengthening nails between October 2014 and April 2019. 15 patients (30 femoral segments) of median age 14 years (interquartile range [IQR] 12-15) were available for analysis. The median follow-up was 29 months (IQR 27-37) after nail implantation. RESULTS: The median distraction length per segment was 49 mm (IQR 47-51) with a median distraction index of 1.0 mm/day (IQR 0.9-1.0), and a median consolidation index of 20 days/cm (IQR 17-23). Reliability of the lengthening nails was 97% and their calculated accuracy and precision were 96% and 95%, respectively. The most common complication was temporary restriction of knee range of motion during distraction in 10 of 30 of the lengthened segments. 1 patient was treated with 2 unplanned additional surgeries due to premature consolidation. CONCLUSION: The method is reliable and accurate with few complications.

Morphology of the knee after guided growth using tension-band devices: a retrospective multicenter study of 222 limbs and 285 implants.

BACKGROUND AND PURPOSE: Temporary hemiepiphysiodesis by tension-band devices is commonly applied to correct angular limb deformities in children. We aimed to evaluate knee joint morphology after guided growth using these devices. PATIENTS AND METHODS: In a retrospective multicenter study we analyzed standardized anteroposterior long-leg radiographs of 222 limbs (285 implants) of patients treated by temporary hemiepiphysiodesis with either eight-Plates or FlexTacks for coronal angular deformities of the knee joint between 2013 and 2019. Femoral floor angle (FFA), femoral notch-intercondylar distance (FNID), and tibial roof angle (TRA) were measured pre- and postoperatively to assess the central knee joint morphology. Statistical exploratory analyses were performed using linear mixed models, t-tests, Wilcoxon signed-rank test, and Mann-Whitney U test. RESULTS: 217 FlexTacks (femur 106, tibia 111) in 104 children and 68 eight-Plates (femur 61, tibia 7) in 35 children were identified. Median time period under growth guidance was 11 months (range 4-42). No statistically significant change in the FFA was detected (eight-Plate: P = 0.2; FlexTack: P = 0.3). A statistically significant difference of the FNID was found in the eight-Plate group (P = 0.02), but not in the FlexTack group (P = 0.3). While TRA increased in both groups, a statistical significance was observed only in the FlexTack group (P < 0.01). CONCLUSION: We found minor but clinically irrelevant changes in knee morphology after the treatment.

Antegrade Intramedullary Femoral Lengthening and Distal Temporary Hemiepiphysiodesis for Combined Correction of Leg Length Discrepancy and Coronal Angular Deformity in Skeletally Immature Patients.

Leg length discrepancies (LLD) are frequently associated with coronal malalignment. Temporary hemiepiphysiodesis (HED) is a well-established procedure for the correction of limb malalignment in skeletally immature patients. For treatment of LLD > 2 cm, lengthening with intramedullary devices gains increasing popularity. However, no studies have investigated the combined application of HED and intramedullary lengthening in skeletally immature patients. This retrospective single-center study evaluated the clinical and radiological outcomes of femoral lengthening with an antegrade intramedullary lengthening nail combined with temporary HED performed in 25 patients (14 females) between 2014 and 2019. Temporary HED through the implantation of flexible staples of the distal femur and/or proximal tibia was either performed prior (n = 11), simultaneously (n = 10) or subsequently (n = 4) to femoral lengthening. The mean follow-up period was 3.7 years (±1.4). The median initial LLD was 39.0 mm (35.0-45.0). Twenty-one patients (84%) presented valgus and four (16%) showed varus malalignment. Leg length equalization was achieved in 13 of the skeletally mature patients (62%). The median LLD of the eight patients with residual LLD > 10 mm at skeletal maturity was 15.5 mm (12.8-21.8). Limb realignment was observed in nine of seventeen skeletally mature patients (53%) in the valgus group, and in one of four patients (25%) in the varus group. Combining antegrade femoral lengthening and temporary HED is a viable option to correct LLD and coronal limb malalignment in skeletally immature patients; however, achieving limb length equalization and realignment may be difficult in cases of severe LLD and angular deformity, in particular.

Guided growth: angular deformity correction through temporary hemiepiphysiodesis with a novel flexible staple (FlexTack).

Temporary hemiepiphysiodesis (HED) is applied to children and adolescents to correct angular deformities (ADs) in long bones through guided growth. Traditional Blount staples or two-hole plates are mainly used for this indication. Despite precise surgical techniques and attentive postoperative follow-up, implant-associated complications are frequently described. To address these pitfalls, a flexible staple was developed to combine the advantages of the established implants. This study provides the first results of guided growth using the new implant and compares these with the established two-hole plates and Blount staples. Between January 2013 and December 2016, 138 patients (22 children, 116 adolescents) with genu valgum or genu varum were treated with 285 flexible staples. The minimum follow-up was 24 months. These results were compared with 98 patients treated with 205 two-hole plates and 92 patients treated with 535 Blount staples. In long-standing anteroposterior radiographs, mechanical axis deviations (MADs) were measured before and during treatment to analyze treatment efficiency. The evaluation of the new flexible staple was performed according to the idea, development, evaluation, assessment, long-term (IDEAL) study framework (Stage 2a). Overall, 79% (109/138) of patients treated with flexible staples achieved sufficient deformity correction. The median treatment duration was 16 months (interquartile range (IQR) 8 to 21). The flexible staples achieved a median MAD correction of 1.2 mm/month/HED site (IQR 0.6 to 2.0) in valgus deformities and 0.6 mm/month/HED site (IQR 0.2 to 1.5) in varus deformities. Wound infections occurred in 1%, haematomas and joint effusions in 4%, and implant-associated complications in 1% of patients treated with flexible staples. Valgus AD were corrected faster using flexible staples than two-hole plates and Blount staples. Furthermore, the median MAD after treatment was lower in varus and valgus AD, fewer implant-associated complications were detected, and reduced implantation times were recorded using flexible staples. The flexible staple seems to be a viable option for guided growth, showing comparable or possibly better results regarding correction speed and reducing implant-associated complications. Further comparative studies are required to substantiate these findings.

Preliminary results of two novel devices for epiphysiodesis in the reduction of excessive predicted final height in tall stature.

BACKGROUND: In the treatment of tall stature, the reduction of excessive predicted final height can either be achieved by hormonal treatment or surgically by temporary (tED) or permanent (pED) epiphysiodesis. The present study evaluates the preliminary results of two novel devices for tED and pED around the knee to reduce the predicted final height. MATERIALS AND METHODS: A retrospective analysis was performed to evaluate the clinical and radiographic outcome after bilateral epiphysiodesis for the treatment of tall stature. A cohort of 34 patients (16 girls, 18 boys) who underwent either tED or pED between 2015 and 2020 were eligible for analysis based on the electronic patient records and picture archiving and communication system of our orthopaedic teaching hospital. tED was conducted in 11 patients (32%) through bilateral implantation of four RigidTacks™ (Merete, Berlin, Germany) around the knee. Twenty-three patients (68%) received pED, performed with an EpiStop™ trephine (Eberle, Wurmberg, Germany). The mean overall follow-up time was 2.9 years. RESULTS: The mean age at surgery was 12.3 years in girls and 13.2 years in boys. Patients had a mean body height of 175.2 cm in girls and 184.7 cm in boys at surgery. The mean predicted final height was 191.4 cm in girls and 210.4 cm in boys. At the last follow-up, 26 patients (76.5%) had achieved skeletal maturity. The mean height of skeletally mature patients was 187.2 cm in girls and 198.5 cm in boys. A mean reduction of the predicted final height of 5.9 cm in girls and 8.7 cm in boys was achieved, corresponding to a reduction in remaining growth of 46% in girls and 38% in boys. Secondary frontal plane deformities of the knee were detected in 5/11 patients (45.5%) in the tED group and 1/23 treatments (4.3%) in the pED group. CONCLUSIONS: tED and pED have both proven to be efficient at achieving growth inhibition to reduce excessive predicted height. However, tED has been associated with an increased risk of secondary angular deformities of the knee. Furthermore, the risk of implant-related complications and the necessity of a subsequent surgical intervention for implant removal have led our study group to abandon tED when treating tall stature. Long-term results of both procedures are pending.

Reconstructive Approaches in Surgical Management of Congenital Pseudarthrosis of the Tibia.

Treatment of congenital pseudarthrosis of the tibia remains a major challenge in pediatric orthopedics. Ideal timing and preference of surgical procedures are discussed controversially. A variety of reconstructive treatment strategies have been described in literature, but so far none has proven its superiority. The aim of treatment is to obtain long-term bone union, to prevent refracture, and to correct angular deformities and leg length discrepancies. This study retrospectively evaluates the outcome of different reconstructive strategies. Sixty-nine patients were identified who presented to our outpatient department between 1997 and 2019. Twenty-six of these patients underwent reconstructive surgical treatment and were included in this study. The study cohort was divided into three groups. Excision of the pseudarthrosis was performed in all patients in Group A and B, and in two patients of Group C. Group A (six/26 patients) received subsequent bone transport through external fixation maintaining original length. In Group B (15/26 patients), patients underwent either previous, simultaneous, or subsequent extrafocal lengthening through external fixation to reconstitute length. In Group C (five/26 patients), internal fixation with intramedullary nails was applied. Radiological and clinical evaluation was performed to assess bone union and complication rates. Results varied considerably between the study groups. Overall, the primary bone fusion rate was 69.2%. There were four refractures, all occurring in Group B. The long-term bone union rate without refracture was 53.8%. The overall complication rate was 53.8% and 23.1% showed persistent pseudarthrosis. Two secondary amputations were performed due to failed bone fusion. In conclusion, excision of the pseudarthrosis and extrafocal lengthening achieves a satisfying bone union rate and limb reconstruction, while bone transport does not offer significant advantages but shows higher complication rates. Intramedullary stabilization should be applied to maintain bone union, but shows lower bone union rates when used as a stand-alone treatment regimen. Regardless of the primary bone fusion rates, the probability of long-term bone union remains unpredictable.