Temporary hemiepiphysiodesis with blount staples and eight-plates in pigs

Percutaneous epiphysiodesis transphyseal screw versus tension-band plating as hemiepiphysiodesis in treating coronal angular knee deformities: a systematic review and meta-analysis of comparative studies

BACKGROUND

Angular knee deformities such as genu varum and genu valgum are common in children and can impact their functional mobility and quality of life. Although surgical interventions like guided growth plates or tension-band plates (TBP) and percutaneous epiphysiodesis transphyseal screws (PETS) are commonly used, comparative analyses of their efficacy and safety are limited. This study aims to evaluate the correction rates and safety profiles of TBP and PETS in treating pediatric coronal angular knee deformities.

METHODS

A comprehensive literature search was conducted in Scopus, Web of Science, and PubMed until November 2024. Only comparative clinical studies comparing PETS and TBP in pediatric patients with coronal knee deformities were included.

RESULTS

A total of five studies encompassing 473 physes were included. Their methodological quality was assessed using the MINORS criteria, with scores ranging from 18 to 19, indicating a low risk of bias. PETS demonstrated significantly higher correction rates compared to TBP, with an overall pooled mean difference in angular correction of 0.17°/month (p < 0.0003). In the femoral subgroup analysis (LDFA), the mean difference correction rate was 0.21°/month in favor of PETS (p = 0.01). Additionally, the PETS group achieved a statistically significant mechanical axis deviation mean difference correction rate of 1.02 mm/month (p = 0.006). Complication rates were relatively lower with PETS across all included studies.

CONCLUSION

PETS achieves faster angular and mechanical axis deviation correction rates compared to TBP, highlighting its efficiency in treating pediatric coronal angular knee deformities. Additionally, PETS demonstrates relatively fewer complications, reinforcing its position as a more effective and cost-efficient option for guided growth in children.

CLINICAL TRIAL NUMBER

Not applicable.

LEVEL OF EVIDENCE

II.

Comparison of histomorphometric and radiographic effects of growth guidance with tension-band devices (eight-Plate and FlexTack) in a pig model

Background and purpose - Temporary hemiepiphysiodesis for growth modulation in skeletally immature patients is a long-known technique. Recently the use of tension-band devices has become popular. This study compares 2 tension-band implants (eight-Plate and FlexTack) regarding their effects on the growth plate.Animals and methods - 12 pigs in 2 equally sized groups (A and B) were investigated. The right proximal medial tibia was treated with either eight-Plate or FlexTack. The left tibia of the same pig was treated with the opposite implant. After 9 weeks all implants were removed. Animals in group B were then hosted for another 5 weeks. Histomorphometric analysis of the growth plate was carried out after 9 and 14 weeks, respectively. Radiographs were taken at implantation, removal, and after 14 weeks.Results - Both tension-band devices achieved a statistically significant and clinically relevant growth inhibition, whereas the effect appeared to be more distinct after the use of FlexTack. Implant-related complications or physeal damage was not observed. After implant removal, rebound phenomenon was radiologically observed in all cases. The growth plates treated with eight-Plate showed a paradox reversal of the zonal distributions, with an increase of the proliferative zones at the previously arrested medial aspect of the physis and a decrease laterally.Interpretation - Both eight-Plate and FlexTack proved to be appropriate devices for growth-guiding treatment. The radiographic evaluation showed a change in angular axes after treatment with each implant, while the correction appeared to be faster with FlexTack. The paradox cartilaginous reaction observed after removal of the eight-Plate might be a histopathological correlate for rebound phenomenon.

Tension band plate-guided growth of knee-flexion deformity in arthrogryposis multiplex congenita in which metaphyseal funnelization induced screw encroachment upon the neurovascular bundle

Knee-flexion deformity in arthrogryposis multiplex congenita is treated by serial casting into extension, distal femoral osteotomies, distal femoral-guided growth, hemiepiphysiodesis, external fixation, capsulotomy, and soft-tissue releases. We are aware of four cases treated by distal anterior femoral-guided growth with tension band plates in which an unreported complication occurred: the screws of the tension band plates penetrated the posterior cortex of the femur during remodeling with metaphyseal funnelization risking the neurovascular bundle. Inclusion criteria were cases with arthrogryposis multiplex congenita and knee-flexion deformity, treatment at our institution by distal anterior femoral-guided growth with tension band plates, and radiographic evidence of posterior cortex screw penetration during remodeling from growth. Six knees (four cases) met the inclusion criteria. The average age at the distal anterior femoral-guided growth with tension band plate operation was 5.8 years. Radiographs after 6.6 years of follow-up showed that the screws of the tension band plates, which at surgery were intrametaphyseal, had penetrated the posterior cortex of the femur. Four knees (two cases) had diffuse pain around the knee to lower leg area, and instrumentation removal alleviated the symptoms. During distal anterior femoral-guided growth with tension band plate operation for knee-flexion deformity in arthrogryposis multiplex congenita, we found that the screws of the tension band plates, which were initially located inside the metaphysis, may protrude through the posterior bone cortex during metaphyseal funnelization with growth, and may encroach upon the neurovascular tissues. Level of evidence: Level IV - case series.

Hemiepiphysiodesis using tension band plates: does the initial screw angle influence the rate of correction?

PURPOSE

When using tension band plates for angular deformity correction, the literature is unclear regarding the most effective screw insertion angle to use. This study evaluates the correlation between initial screw angle and the average rate of correction during hemiepiphysiodesis using tension band plates.

METHODS

This retrospective study includes 35 patients (47 physes) with genu valgum deformity (17 idiopathic and 18 fibular hemimelia) who underwent insertion of Eight-Plates between 2010 and 2015. Initial screw angle was determined from the intraoperative fluoroscopic images. Radiographs were obtained within three months of surgery, and follow-up films were obtained every three to six months. Change in mechanical lateral distal femoral angle, medial proximal tibial angle and screw angle was obtained from each follow-up radiograph. Initial screw angle was correlated with the average rate of correction during the entire treatment period. The average rate of angular correction during first and last follow-up periods was also compared.

RESULTS

The relationship between the initial screw angle and the mean rate of angular correction was not statistically significant (p = 0.2). The rate of angular correction during the first follow-up period (mean of 4.7 months) was 0.86° per month compared with 0.71° per month during the last follow-up period (mean of 5.1 months).

CONCLUSION

Application of a tension band plate with a divergence angle ranging from 0° to 30° results in similar rates of angular correction. For surgeons inserting screw-plate tension band devices, there does not seem to be any necessity to make the screws parallel or divergent. We recommend that screw placement be anatomically correct, i.e. not impinging on the physis, rather than favouring any particular divergence angle.

LEVEL OF EVIDENCE

IV.

Tension band plating is less effective in achieving equalization of leg length

PURPOSE

Little data is available on the efficiency of different implants for epiphysiodesis. The purpose of this study is to compare the efficacy between plates and staples in decreasing leg-length discrepancy.

METHODS

A retrospective review of 19 children who underwent temporary epiphysiodesis of the legs was conducted, with a minimum of two years of follow-up. The bone length and length ratio to the short side were measured at six months, one year and two years postoperatively. The change in discrepancy was compared between staples and plates by an independent t-test, and the shortest time to a significant decrease in discrepancy was determined using a paired t-test.

RESULTS

Ten patients underwent 13 staple procedures in nine femurs and four tibias for a 2.8-cm discrepancy at age 11.8 years, and nine patients underwent 14 plate procedures in seven femurs and seven tibias for a 3.1-cm discrepancy at age 12.4 years. Patients were followed up to skeletal maturity, except two. The use of staples decreased the discrepancy in the bone ratio from +4.8% to +1.2% in two years, and the use of plates decreased this ratio from +5.1% to +3.3% in two years. The change in the length ratio was significantly greater after stapling. Six months were required after stapling before the first significant decrease in discrepancy; it took two years after plating.

CONCLUSIONS

This study showed a significantly lower efficacy for decreasing leg-length discrepancy by tension band plating. Orthopaedic surgeons should be aware of the limitations of using plates for suppressing bone growth.

LEVEL OF EVIDENCE

III.

Radiographic Results and Complications of 3 Guided Growth Implants

BACKGROUND

Temporary, implant-mediated hemiepiphysiodesis (ie, guided growth) is an effective and popular treatment method for lower extremity angular deformities. The purpose of this study was to retrospectively evaluate the safety profile of 3 different implants used to correct lower extremity angular deformities in pediatric patients.

METHODS

We retrospectively reviewed a consecutive series of pediatric patients with lower extremity angular deformities who underwent implant-mediated guided growth by 2 surgeons at our institution between 2004 and 2014. Implants were selected according to surgeon preference and included the Biomet peanut plate, Orthofix eight-plate, and Pega Medical hinge plate. Medical records and radiographs were reviewed to assess deformity correction, implant integrity, and complications.

RESULTS

During the study period, 115 plates (63 Biomet peanut plates, 30 Orthofix eight-plates, and 22 Pega Medical hinge plates) were implanted in 52 patients (24 males, 28 females). Average age at implantation was 11.7 years (12.3 y in males, 11.1 y in females). Average length of follow-up was 18.4 months. There was no significant difference in rate of deformity correction between the implant types (P=0.08).Three broken screws (2.6%) were observed, all of which involved cannulated screws in peanut plates. Four peanut plates (6.3%) had an implant-related complication: 3 broken screws and 1 screw pullout. Three eight-plates (10.0%) had screw pullout. No complications were observed within either the hinge plate or solid screw groups. Implant-related complications were significantly associated with increased body weight and cannulated screw use (P=0.02 and 0.03, respectively), but not bone age, sex, plate type, or rate of deformity correction. No deep infections, premature growth arrests, or plate breakages were observed.

CONCLUSIONS

Implant-mediated guided growth is a safe technique for pediatric lower extremity angular deformity correction with a low complication rate. This study demonstrated that overweight patients had a significantly higher rate of implant-related complications. Screw breakages were only observed with cannulated screws in peanut plates. Thus, we recommend using solid, noncannulated screws in overweight children who are at an increased risk of implant failure.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

Growth modulation for coronal deformity correction by using Eight Plates-Systematic review

Introduction

Coronal deformities are commonly encountered in paediatric orthopaedics and surgical treatment is indicated for severe deformities causing pain, function and cosmetic problems. In a growing bone, major surgical intervention like osteotomy with internal or external fixation can be avoided by growth modulation (hemiepiphysiodesis) using 8-plates. Our aim is to review the published literature on the use of 8-plates for deformity correction.

Methods

We conducted a systematic review on 8-plate growth modulation for coronal deformity correction. We carried out detailed literature search on PubMed, Google Scholar, EMBASE, and Cochrane databases. We analysed selected studies for patient demographics, rate of deformity correction, clinical outcome and complications.

Results

We identified seven studies using 8-plate for deformity correction involving 215 patients (350 Limbs). The mean age was 9.5 years (2-16 years M/F Ratio 1.1:1); underlying aetiology was Idiopathic in 33% and Pathological 67% cases. The deformities were successfully corrected in 196/215 patients (91.2%) and partial/no correction in 19/215 patients (8.8%). The mean time to correction was 15.3 Months (10.3-25) and follows up of 18.9 months (12.4-24). The deformity corrected at 1.28 °/month (0.93-1.53), lateral distal femoral angle changed at 0.87°/month (0.65-1.0) and medial proximal tibial angle changed at 0.72 (0.5-1). Complications were reported in 12/215 patients (5.6%) including hardware failure in 5, overcorrection/leg length difference in 5, infection 1 and stiffness 1. The rebound was reported in 8 patients (3.7%).

Conclusion

Growth modulation with 8-plates has high efficacy and low complications for deformity correction; and has been used widely across all paediatric age groups and aetiology. The literature is mostly retrospective and heterogeneous to develop age and aetiology specific recommendations.

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.

A comparison between a hinged plate and screw system and a conventional tension-band plate and screw system used for correction of an angular deformity of the lower limb: an animal study

BACKGROUND

The purpose of the animal study is to introduce a newly designed hinged plate and screw system for correction of angular deformities of the lower limbs. The technique was compared with the use of a conventional tension-band plate and screw system.

METHODS

This is a randomized controlled animal trial. Eight 3-month-old Bama miniature pigs were used to establish animal models. In each animal, one leg was randomly allocated into study group and another leg into control group. Legs of the study group were corrected with a hinged plate and screw system, and legs of the control group were corrected with a conventional tension-band plate and screw system. The corrective rates of medial slope angle, medial proximal tibial angle, and angle of the two arms of the hinged plate were measured. Residual stress on the implants was also evaluated. A P < 0.05 was statistical significant.

RESULTS

At the final measurements of 18 weeks, the mean corrective rates of medial slope angle, medial proximal tibial angle, and angle of the two arms of the study group were 0.71°/week, 0.85°/week, and 2.18°/week, respectively; the data in the control group were 0.84°/week, 0.89°/week, and 2.13°/week, respectively. No significant difference was found between the groups regarding the mean corrective rates of the angles (P < 0.05). The mean residual stress in the study group was 643.35 MPa, and measurement in the control group was 1,273.63 MPa, with a significant difference (P < 0.05).

CONCLUSIONS

Compared to the conventional tension-band plate and screw system, the hinged plate and screw system may be more reliable for correction of angular deformities of the lower limb.

Temporary hemiepiphysiodesis of the distal medial femur: MPFL in danger

INTRODUCTION

Temporary hemiepiphysiodesis (TH) with plate fixation is a well-accepted and common treatment for correcting leg malalignment in skeletally immature patients. The purpose of this study was to investigate any soft tissue damage caused during TH at the distal medial femur with a plate and two screws. We hypothesized that correct plate placement can affect the integrity of the medial stabilizing structures of the knee, especially the medial patellofemoral ligament (MPFL), the medial collateral ligament (MCL) or result in arthrotomy of the knee joint itself.

MATERIALS AND METHODS

In eight cadaveric knees of five adult humans a TH was performed with a plate and two cancellous screws at the distal medial femur using a standardized surgical technique. Subsequently the medial capsular and ligamentous structures were systematically exposed and assessed. Capsular and synovial tissue was also inspected for impingement by the plate or screws.

RESULTS

In all knees the MPFL was present. In two specimens the MPFL was intact and the plate was lying over the dorsal part of the MPFL close to the MCL. The MPFL was completely cut in two cases in the central part of the ligament. In four cases the MPFL was partially dissected or perforated by a screw and fixed to the femur by the plate. The MCL was intact and not impinged by the implant in any case. In total four of eight knees the capsule was transected or perforated by a screw or by a part of the plate, resulting in intraarticular implant placement.

CONCLUSIONS

Standard plate placement during TH on the distal medial femur frequently leads to damage to the MPFL, impingement of the MPFL, the capsular and synovial tissues or exposure of the knee joint.

Controlled longitudinal bone growth by temporary tension band plating

Permanent growth arrest of the longer bone is an option in the treatment of minor leg-length discrepancies. The use of a tension band plating technique to produce a temporary epiphysiodesis is appealing as it avoids the need for accurate timing of the procedure in relation to remaining growth. We performed an animal study to establish if control of growth in a long bone is possible with tension band plating. Animals (pigs) were randomised to temporary epiphysiodesis on either the right or left tibia. Implants were removed after ten weeks. Both tibiae were examined using MRI at baseline, and after ten and 15 weeks. The median interphyseal distance was significantly shorter on the treated tibiae after both ten weeks (p = 0.04) and 15 weeks (p = 0.04). On T1-weighted images the metaphyseal water content was significantly reduced after ten weeks on the treated side (p = 0.04) but returned to values comparable with the untreated side at 15 weeks (p = 0.14). Return of growth was observed in all animals after removal of implants.

Temporary epiphysiodesis can be obtained using tension band plating. The technique is not yet in common clinical practice but might avoid the need for the accurate timing of epiphysiodesis.

Cite this article: Bone Joint J 2013;95-B:855–60.

Similar growth plate morphology in stapling and tension band plating hemiepiphysiodesis: a porcine experimental histomorphometric study

The tension band plating technique for hemiepiphysiodesis is new and advocated because it is believed to reduce the risk of premature closure of the growth plate compared to stapling. The benefit of the tension band plating technique has not yet been proven in experimental or randomized clinical studies. Ten weeks old domestic pigs in two randomized, paired studies were used. Right proximal tibia was randomized to medial epiphysiodesis by either stapling or tension band plating. Left side received the opposite treatment. Study A (n = 10): 9 weeks treatment. Study B (n = 8): implant removal after 9 weeks of treatment and 5 weeks of housing. Fractions of the chondrocyte layers were determined using quantitative histomorphometry. Mean heights of the growth plates were measured. No significant changes were observed between histomorphometric parameters in neither study A or B. Areas with disorganized cartilage tissue were abundant in 13/16 samples from study B and observed after both treatment with tension band plating and staples. Chondrocyte zone fractions did not differ between tension band plating and staple treatment in this randomized, paired animal study. The growth plate responded to release of hemiepiphysiodesis with abundant disorganized cartilage tissue in both groups. The histological response to hemiepiphysiodesis by tension band plating and staples appear to be similar.

Hemiepiphysiodesis: similar treatment time for tension-band plating and for stapling: a randomized clinical trial on guided growth for idiopathic genu valgum

BACKGROUND

In children with angulating deformities of the lower limbs, hemiepiphysiodesis can be used to guide growth to achieve better alignment at skeletal maturity. Traditionally, this has been performed with staples. The tension-band plating technique is new and it has been advocated because it is believed to reduce the risk of premature closure of the growth plate compared to stapling. The benefit of the tension-band plating technique has not yet been proven in experimental or randomized clinical studies.

METHODS

We performed a randomized clinical trial in which 26 children with idiopathic genu valgum were allocated to stapling or tension-band plating hemiepiphysiodesis. Time to correction of the deformity was recorded and changes in angles on long standing radiographs were measured. Pain score using visual analog scale (VAS) was recorded for the first 72 h postoperatively. Analgesics taken were recorded by the parents.

RESULTS

Mean treatment times for stapling hemiepiphysiodesis (n = 10) and for tension-band plating hemiepiphysiodesis (n = 10) were similar. Postoperative VAS scores and consumption of analgesics were also similar in both groups. No hardware failure or wound-related infection was observed.

INTERPRETATION

Treatment time for the 2 treatment modalities was not significantly different in this randomized clinical trial. Tension-band plating and stapling appeared to have a similar effect regarding correction of genu valgum. We cannot rule out type-II error and the possibility that our study was underpowered. ClinicalTrials.gov Identifier: NCT01641354.

Screw length in the guided growth method

BACKGROUND

The appearance of the 8-plate as a method for hemiepiphysiodesis has renewed the interest for the use of this technique. However, many questions remain unanswered about the way of action of the guided growth method. Although screw length has been said to play no role, to our knowledge, no clinical or experimental evidence exists.

METHODS

An experimental prospective randomized study with 40 WNZ Rabbits aged 8 weeks was conducted. Four experimental groups were established. Each tibia was randomly allocated to one of the following groups: Staples (group 1), 8-plate either using self-taping screws of 9 mm (group 2), or 5 mm lengths (groups 3) and control (group 4). Radiological assessment of the tibial deformity was done in a weekly fashion, and ALDA (articular line-diaphyseal angle) variations at 6 weeks were used as the control variable.

RESULTS

The 8-plate as a whole produced a significant bigger deformity than the staples (10°). No significant differences between the two models of the 8-plate were found along the study (3.7°).

CONCLUSIONS

The 8-plate has shown to be more efficient in producing angular deformity than staples. However, the length of the screw has showed no role in the 8-plate function.