Screw length in the guided growth method

Anterior Distal Femoral Hemiepiphysiodesis Using Coronally Oriented 8-plates for the Correction of Fixed Knee Flexion Deformities in Children-Preliminary Results

INTRODUCTION

The original technique for guided growth of the distal femur for correction of pediatric fixed knee flexion deformities (FKFDs) involves the utilization of two 8-plates inserted on either side of the trochlear groove, a technique that has been frequently linked to the development of persistent postoperative knee pain and crepitus. The present study aimed to assess the preliminary results of a novel technique where the two 8-plates are fixed in the coronal plane, one on each of the medial and lateral surfaces, so that they occupy the anterior part of the distal femur.

METHODS

Our study was a prospective case series that included cases with FKFD of >10 degrees in children with at least 12 months of predicted growth remaining. The preoperative knee flexion contracture angle was documented. The surgical procedure entailed the insertion of 2 coronally oriented 8-plates on the medial and lateral surfaces of the distal femur as anterior as possible to the axis of the femur without encroachment on the trochlear groove. The duration of time required to attain full knee extension and any complications encountered were recorded. Wilcoxon signed-rank was used to compare the preoperative and final contracture angles. The level of statistical significance was set at P<0.05.

RESULTS

Thirteen knees in 8 patients (6 boys and 2 girls) were included. The median age was 11 years (6 to 14). There was a significant improvement in the FKFD for the whole cohort from 25 degrees (14 to 42) to 0 degrees (-9 to 8), P<0.05. The median rate of correction was 2.0 degrees/month (0.9 to 5.8). The time till full correction was 14 months (4 to 25). Postoperative knee pain and metalware-related complications were not reported by any patient during follow-up.

CONCLUSIONS

Guided growth of the distal femur using coronally oriented 8-plates is an effective procedure for the treatment of FKFDs in children. This modified technique may achieve faster correction while minimizing the risk of postoperative knee pain compared with the conventional technique.

LEVEL OF EVIDENCE

Level IV-case series.

Anterior Hemiepiphysiodesis of the Distal Tibia: A Step-by-step Surgical Technique Guide

Aim

This paper aims to serve as a guide for surgeons to prepare, execute, and perfect anterior hemiepiphysiodesis of the distal tibia (AHDT).

Background

Treatment of persistent or recurrent equinus deformity following multiple conservative and surgical interventions in patients with idiopathic clubfoot or neuromuscular conditions can be challenging, and multiple surgical options are presented in the existing literature. Anterior hemiepiphysiodesis of the distal tibia is an option that seems to be safe and efficient in treating this entity. To the best of our knowledge, there is not yet any detailed description of this surgical technique in the English literature.

Technique

The AHDT detailed surgical technique includes patient positioning, careful distal anterior tibial approach, placement of guided growth plates, fixation with epiphyseal and metaphyseal screws under fluoroscopic guidance, meticulous closure, and postoperative measures.

Conclusion

This guide can be used pre-operatively to plan the surgery, intra-operatively to aid in smooth and safe step progression, and post-operatively to assist in critical critiquing.

Clinical significance

By understanding the various stages of the surgery as well as the anatomy, pitfalls can be avoided and AHDT can be performed efficiently.

How to cite this article

Katz A, Dumas É, Hamdy R. Anterior Hemiepiphysiodesis of the Distal Tibia: A Step-by-step Surgical Technique Guide. Strategies Trauma Limb Reconstr 2023;18(3):174-180.

Application of three-dimensional printed navigation templates to correct lower limb deformities in children by the guided growth technique

Objective

Currently, individualized navigation templates are rarely applied in pediatric orthopedic surgery. This study aimed to explore the potential of navigation templates obtained using computer-aided design and three-dimensional (3D) printing to correct lower limb deformities in children by the guided growth technique.

Methods

We prospectively studied 45 children with leg length discrepancy (LLD) or lower limb angular deformities, who underwent guided growth surgery involving 8-plate. In total, 21 and 24 children were included in the navigation template (group A) group and in the traditional surgery (group B) group, respectively. Mimics software was used for designing and printing navigation templates. The operation time, X-ray radiation exposure, damage to cartilage, and postoperative complications were recorded.

Results

The mean operation time in groups A and B were 20.78 and 28.39 min, respectively, and the difference was statistically significant. Compared with group B, the intraoperative exposure of X-rays in group A was reduced by 25% on average. After 9–24 months of follow-up, the deformities were corrected in both groups. No significant differences in the treatment effect were noted between the groups, and no complications occurred.

Conclusions

Using the individualized navigation template in the guided growth technique made the surgical procedure convenient and simple to perform. In addition, the operation time and intraoperative exposure to X-rays were reduced. We consider that 3D printed navigation templates can facilitate the accurate completion of corrective surgeries for lower limb deformities in children, which is worthy of promotion and application.

Hemiepiphysiodesis for coronal angular knee deformities: tension-band plate versus percutaneous transphyseal screw

INTRODUCTION

Pediatric coronal plane knee deformities can be treated surgically using hemiepiphysiodesis. The two leading techniques used for hemiepiphysiodesis are: tension-band plates (TBP) and percutaneous transphyseal screws (PETS). We hypothesized that PETS would lead to faster guided correction of angular knee deformities than TBP.

MATERIALS AND METHODS

A retrospective cohort of 35 patients treated with either TBP or PETS in one medical institution was established. The cohort included both genu varum and genu valgum of both primary and secondary etiologies. We first compared the treatment groups for differences in demographic and malalignment characteristics. Then, we compared the treatment groups for differences in operation-related outcomes, radiological mechanical correction and complication rates.

RESULTS

We found that the use of PETS, compared to TBP, was associated with a faster implantation surgery and a shorter interval between implantation and removal, i.e., faster correction. Furthermore, PETS were associated with faster correction rates of the mechanical axis deviation, lateral distal femoral angle and medial proximal tibial angle. No significant differences in complication rates were found between the two treatments.

CONCLUSION

PETS provided a faster correction of angular knee deformities compared to TBP at similar complication rates. Hence, PETS could be considered a superior technique for hemiepiphysiodesis.

Finite element and biomechanical analysis of risk factors for implant failure during tension band plating

Objective

Tension band plating has recently gained widespread acceptance as a method of correcting angular limb deformities in skeletally immature patients. We examined the role of biomechanics in procedural failure and devised a new method of reducing the rate of implant failure.

Methods

In the biomechanical model, afterload (static or cyclic) was applied to each specimen. The residual stress of the screw combined with different screw sizes and configurations were measured and compared by X-ray diffraction. With regard to static load and similar conditions, the stress distribution was analyzed according to a three-dimensional finite element model.

Results

The residual stress was close to zero in the static tension group, whereas it was very high in the cyclic load group. The residual stress of screws was significantly lower in the convergent group and parallel group than in the divergent group. The finite element model showed similar results.

Conclusions

In both the finite element analysis and biomechanical tests, the maximum stress of the screw was concentrated at the position where the screws enter the cortex. Cyclic loading is the primary cause of implant failure.

Failure of tension band plating: a case series

Growth modulation with tension band plates (TBP) has been shown to be a very useful method for the treatment of angular deformities in growing children. Recently, we have observed cases of failure where the epiphyseal screw was drawn through the physis into the metaphysis. This study describes a series of children who developed this complication. Patients who developed TBP failure after operative treatment of lower limb angular deformities were identified from the databases at four institutions over a 5-year period. The medical records were reviewed to record demographics, primary diagnoses, details of the operative procedure, development of physeal arrest, and recurrence of the original deformity. Six patients (five girls) with nine implant failures were identified. The mean age of the children at the time of implant insertion was 7.2 years (range, 4-10 years). The primary diagnoses included hypophosphatemic rickets (n=7), congenital pseudoarthrosis of the tibia associated with neurofibromatosis 1 (n=1), and post-traumatic malunion after distal tibial fracture (n=1). Of the nine TBP that presented with the complication, four were inserted into the medial distal femur (one bilateral case), two into the medial proximal tibia (one bilateral case), two into the lateral distal tibia, and one into the medial distal tibia. None of these patients developed physeal growth arrest at the last follow-up as assessed on the latest radiographs. The use of TBP for guided growth in patients younger than 10 years old with rickets, neurofibromatosis, or other conditions that produce osteopenia leads to an increased risk for implant failure. In these cases, it is important to confirm that the epiphyseal screw has good purchase. Patients with these features should be monitored closely for early detection of this complication.

Poor Efficiency of Eight-Plates in the Treatment of Lower Limb Discrepancy

BACKGROUND

Among the numerous existing epiphysiodesis procedures, the eight-plate-guided growth technique, initially described for angular deformities correction, has progressively gained popularity among pediatric orthopaedic surgeons to treat lower limb discrepancy (LLD). The goal of this study was to assess the efficacy of eight-plates in LLD.

METHODS

All children treated for LLD with eight-plates were prospectively included and followed until skeletal maturity. Efficacy of the epiphysiodesis was calculated 6 and 18 months postoperatively and at latest follow-up, according to a method previously validated for percutaneous epiphysiodesis using transphyseal screws (PETS). Radiologic measurements were performed using 3-dimensional low-dose stereoradiography. Intraoperative and postoperative complications were reported.

RESULTS

Thirty-two patients were included (average age at surgery, 12.5 y). For femoral epiphysiodesis, efficacy was only 23% at 6 months and 68% at latest follow-up. The procedure was even less efficient on the proximal tibia, with only 42% of the expected growth arrest at latest examination. Eight patients (20%) experienced plate-related pain during follow-up, and 5 physes (12.5%) required unplanned revision surgery.

CONCLUSIONS

Results of the current series show that the eight-plate technique procedure was associated with few perioperative complications, but the growth arrest observed at follow-up was unpredictable and lower than that achieved with PETS in previous reports. Eight-plate procedures cannot be considered as an efficient epiphysiodesis technique in comparison with standard technique.

LEVEL OF EVIDENCE

Level IV.

Guided growth: mechanism and reversibility of modulation

In paediatric orthopaedics, deformities and discrepancies in length of bones are key problems that commonly need to be addressed in daily practice. An understanding of the physiology behind developing bones is crucial for planning treatment. Modulation of the growing bone can be performed in a number of ways. Here, we discuss the principles and mechanisms behind the techniques. Historically, the first procedures were destructive in their mechanism but reversible techniques were later developed with stapling of the growth plate being the gold standard treatment for decades. It has historically been used for both angular deformities and control of overall bone length. Today, tension band plating has partially overtaken stapling but this technique also carries a risk of complications. The diverging screws in these implants are probably mainly useful for hemiepiphysiodesis. We also discuss new minimally invasive techniques that may become important in future clinical practice.

Growth Retardation (Hemiepiphyseal Stapling) and Growth Acceleration (Periosteal Resection) as a Method to Improve Guided Growth in a Lamb Model

BACKGROUND

Guided growth corrects pediatric limb deformity by inhibiting growth on the convexity of the bone. Both modular and rigid implants have been used; we endeavor to determine whether a clear advantage of one implant exists. We further hypothesize that improved correction could be realized by accelerating growth with resection of the periosteum.

METHODS

Sixteen lambs underwent guided growth of the medial proximal tibia (the opposite limb served as a control). Group 1 used a rigid staple (n=5); group 2 a modular plate and screw construct (n=5), and group 3 had a similar device plus periosteal resection (n=6). Radiographs tracked the progression of deformity in the coronal plane. Before sacrifice, pulsed fluorochrome labels allowed for temporal and spatial growth rate analysis. At sacrifice, True Deformity was calculated (and compared with control tibia) from standardized radiographs in the coronal and sagittal planes. Device Efficiencies were normalized by dividing True Deformity produced (degrees) by the Expected Growth gain (mm) from the control limb.

RESULTS

Group 3 produced greater coronal plane deformity than group 1 by an average of 2.2 degrees per month (P=0.001) and group 2 by an average of 2.4 degrees per month (P=0.0007). At sacrifice, groups 1 and 2 were equally effective at limiting growth to 75% of control; no differences in growth retardation were noted. No differences in Device Efficiency were noted between groups 1 and 2. The Device Efficiency was significantly different between groups 1 and 2 with comparison with group 3 (P=0.05 and P=0.022); with a 2.5 degree/mm faster deformation in the stripped cohort.

CONCLUSIONS

Rigid implants initially produced deformity quicker than modular constructs; yet ultimately, both implants were equally effective at guiding growth. Device Efficiency for the modular group improved significantly with the addition of periosteal stripping as method to accelerate growth.

Rebound growth after hemiepiphysiodesis: An animal-based experimental study of incidence and chronology

Rebound growth after hemiepiphysiodesis may be a normal event, but little is known about its causes, incidence or factors related to its intensity. The aim of this study was to evaluate rebound growth under controlled experimental conditions. A total of 22 six-week-old rabbits underwent a medial proximal tibial hemiepiphysiodesis using a two-hole plate and screws. Temporal growth plate arrest was maintained for three weeks, and animals were killed at intervals ranging between three days and three weeks after removal of the device. The radiological angulation of the proximal tibia was studied at weekly intervals during and after hemiepiphysiodesis. A histological study of the retrieved proximal physis of the tibia was performed. The mean angulation achieved at three weeks was 34.7° (standard deviation (sd) 3.4), and this remained unchanged for the study period of up to two weeks. By three weeks after removal of the implant the mean angulation had dropped to 28.2° (sd 1.8) (p < 0.001). Histologically, widening of the medial side was noted during the first two weeks. By three weeks this widening had substantially disappeared and the normal columnar structure was virtually re-established. In our rabbit model, rebound was an event of variable incidence and intensity and, when present, did not appear immediately after restoration of growth, but took some time to appear.

Histological differences between various methods of hemiepiphysiodesis: is guided growth really different?

Traditional systems of hemiepiphysiodesis are based on the application of asymmetrical compression to the physis to correct angular deformities. The guided growth method claims to act as a tension plate avoiding compression. The aim of this study was to confirm or refute this claim. Twenty-four White New Zealand rabbits were subjected to a proximal tibial hemiepiphysiodesis using either staples or a plate and two-screws method. Both methods succeeded in producing deformity. The initial existent histological differences between systems became less apparent after 6 weeks of hemiepiphysiodesis, when histological results were very similar. The findings suggest that the eight-plate system produces, like staples, compression of the physis, but the forces are applied more gradually.

The biomechanics of guided growth: does screw size, plate size, or screw configuration matter?

Guided growth with the eight-plate is a commonly used technique to correct angular limb deformities in children. However, the optimal combination of plate size, screw size, and screw configuration has not been determined. Using osteotomized femoral sawbones and a rail frame, we developed a growth model to examine the effect of these variables at 6-month, 12-month, and 18-month growth increments. The mean annual coronal plane change was 11.3°. Screw size and plate size were not associated with the rate of angular correction. Screw configuration was important, with parallel screws resulting in optimal correction at all time points compared with divergent screws (P<0.05).