Temporary hemiepiphysiodesis using an eight-plate implant for coronal angular deformity around the knee in children aged less than 10 years: efficacy, complications, occurrence of rebound and risk factors

Removal of the Metaphyseal Screw From Tension Band Constructs After Hemiepiphysiodesis: High Rates of Physeal Tethering and Subsequent Implant Removal

BACKGROUND

Removal of the metaphyseal screw from tension band plate constructs after correction of angular deformity in patients treated with hemiepiphysiodesis has been suggested as an alternative to removing the plate and both screws. While this has the potential benefit of easier implant removal and reinsertion in the event of rebound, there is debate in the literature regarding the benefits and risks of leaving the epiphyseal screw and plate in place.

METHODS

Patients treated with hemiepiphysiodesis at the distal femur and/or proximal tibia with tension band plates and screws who underwent subsequent removal of the metaphyseal screw after correction were included. Charts and radiographs were reviewed for the need for metaphyseal screw reinsertion, subsequent removal of deep implants, and evidence of physeal tethering. Tethering was defined as progressive overcorrection in the treated bone segment after removal of the metaphyseal screw with the mechanical axis moving one full mechanical axis zone or more. Patients with tethering were compared with those without.

RESULTS

A total of 215 patients with 387 limbs treated met inclusion criteria. Of those, 175 patients were treated for idiopathic genu valgum, while 40 were treated for other conditions. Fifty-nine individuals (27%) underwent replacement of the metaphyseal screw for repeat angular correction. Fifty-one percent of patients underwent secondary procedures for reasons other than metaphyseal screw reinsertion (74 symptomatic implant removal, 7 elective implant removal, 29 due to tethering). There were 44 cases of tethering in 36 patients (17%). In cases of tethering, 7 patients were treated with observation, 11 with implant removal only, 16 with hemiepiphysiodesis on the opposite side, and 2 with osteotomy. Patients with tethering were significantly younger, more likely to be male, and more likely to have had the metaphyseal screw removed more than once ( P < 0.05).

CONCLUSION

Removal of only the metaphyseal screw after hemiepiphysiodesis has high rates of tethering and further surgery for iatrogenic deformity correction and implant removal. This technique is not recommended.

LEVEL OF EVIDENCE

Therapeutic Level III, case-control study.

Gait Analysis in Patients After Hemiepiphysiodesis Due to Valgus or Varus Knee Deformity

Background: Developmental knee joint deformities are a common problem in pediatric orthopedics. Children with a valgus or varus deformity of the distal femur or the proximal tibia are commonly treated with hemiepiphysiodesis. Gait analysis in patients with lower limb deformities plays an important role in clinical practice. The purpose of our study was to assess gait parameters in patients who underwent hemiepiphysiodesis procedures of the distal femur or proximal tibia due to a knee deformity and to compare them with those in healthy controls. Methods: We prospectively evaluated 35 patients (14 females and 21 males) after hemiepiphysiodesis and compared the results with a healthy control group (26 participants). Gait was analyzed with a G-Sensor device (BTS Bioengineering Corp., Quincy, MA, USA). We assessed the following gait parameters: gait cycle duration, step length, support phase duration, swing phase duration, double support duration, single support duration, cadence, velocity, and step length. We assessed these gait parameters in a group of patients before and after treatment with hemiepiphysiodesis. We compared the patients' results before and after treatment to those of a healthy control group. The level of significance was set at p < 0.05. Results: The mean follow-up period was 13 months. There was no difference in the results of gait assessments in patients prior to and after treatment. The median step length was 47.09% in the treated limb after treatment and 54.01% in the intact limb (p = 0.018). There were no other differences in gait parameters in the treated limbs and the healthy, intact limbs in the patient group after treatment. There were no significant differences in the patients before and after treatment compared with those in the healthy control group in all gait parameters. Conclusions: Valgus or varus knee deformity correction with the use of hemiepiphysiodesis does not significantly improve preoperative gait parameters. The biomechanical outcomes of hemiepiphysiodesis in the treatment of valgus or varus knee deformity are good. We observed no differences in gait cycle duration, step length, support phase duration, swing phase duration, double support duration, single support duration, gait velocity, cadence, or step length between the experimental and healthy control groups.

The Effectiveness of Growth Modulation Using Tension Band Plates in Children With Achondroplasia in Comparison to Children With Idiopathic Frontal Axial Deformities of the Knee

BACKGROUND

Achondroplasia is the most common form of rhizomelic dwarfism. Aside from disproportionally short extremities, frontal knee malalignments are common. We assessed the effectiveness of guided growth via tension band plates in children with achondroplasia in comparison to patients with idiopathic knee deformities using radiography.

METHODS

Twenty children with achondroplasia (8 valgus/31 varus knees) and 35 children with idiopathic knee malalignments (53 valgus/12 varus knees) which underwent temporary hemiepiphysiodesis at the distal femur and/or proximal tibia were retrospectively compared. Radiographic outcomes (mechanical lateral distal femoral angle, medial proximal tibial angle, and mechanical axis deviation) were compared before surgery and plate removal. Correction rates according to plate location were compared as change per implant duration and per growth in leg length.

RESULTS

Achondroplasia patients were younger (9±2 vs.12±2 y), femoral and tibial growth rate was 43.3% and 48.5% lower and implant duration lasted longer: 36.9±8.9 months in valgus knees and 23.0±14.3 months in varus knees versus 13.4±7.9 months in idiopathic valgus and 11.7±4.6 months in idiopathic varus knees. Significant improvements in joint orientation angles and mechanical axis deviation were achieved but femoral and tibial plates achieved slower correction per months in achondroplasia ( P ≤0.031). When normalized to bone growth, the rate of correction in joint orientation angles was no longer significantly different for the femur ( P =0.241), with a trend for slower correction in the tibia ( P =0.066). The corrections in MAD per leg growth (mm/mm) remained smaller ( P =0.001). In achondroplasia, older age correlated with slower MAD correction ( r =-0.36, P =0.022), femoral plates corrected faster than tibial ( P =0.024) and treatment of valgus was less successful than varus involving longer treatments ( P =0.009). More complications occurred in achondroplastic knees ( P =0.012).

CONCLUSIONS

Skeletally immature patients with achondroplasia can benefit from growth modulations, but they need longer treatments and face more complications. Their slower growth does not solely determine the more tenacious success.

LEVEL OF EVIDENCE

Therapeutic Level III-case-control study.

Hemi-Percutaneous Epiphysiodesis Using Transphyseal Screws at Lateral Proximal Tibias After Epiphyseal Fusion of Distal Phalanges in the Hand Results in Undercorrection of Genu Varum

Background and Objectives: To investigate postoperative courses after hemi-percutaneous epiphysiodesis using transphyseal screws (PETS) for genu varum. We especially focused on the degree of skeletal maturation that results in undercorrection. Materials and Methods: We identified patients with idiopathic genu varum treated with hemi-PETS at the proximal tibia and followed-up to the completion of skeletal maturation. The acceptable correction was defined as the (1) final deformity < varus 1.0° or (2) final correction angle obtained by surgery (f-CA) > mean value of preoperative deformity. Results: In our cohort of 29 patients and their 29 lower limbs (one side was randomly selected in bilateral cases), the mean hip-knee-ankle (HKA) alignment was varus 6.5 ± 1.3° at the time of hemi-PETS. The mean f-CA was 5.8 ± 2.0° with a rebound of 0.3 ± 1.0°. Ten patients showed the finding of partial or complete fusion of the epiphysis of distal phalanges in the hand at the time of hemi-PETS (the fusion group, FG). Their f-CA was 4.0 ± 1.9° (with preoperative deformity of 6.9 ± 1.4°), which was significantly smaller than that (6.7 ± 1.3°, p = 0.001) of remaining 19 patients (the open group, OG). The acceptable correction was obtained in all 19 patients of the OG. Otherwise, it was obtained in two patients in the FG (p < 0.001). The other two patients in the FG preoperatively showed a complete epiphyseal fusion of the distal phalanges in the hand, and their f-CA was 0.7 and 1.1°, respectively. Conclusions: The degree of skeletal maturation corresponding to epiphyseal fusion of distal phalanges in the hand results in undercorrection after the hemi-PETS performed at the proximal tibia for genu varum.

Lower limb coronal malalignment correction by percutaneous osteotomy and schanz screws fixation

Pediatric knee deformities are common, and the classic treatment is corrective osteotomy. The aim of this study to assess the safety and efficacy of percutaneous low-energy osteotomy and casting with shanz screws fixation in treatment of Genu varum in children equal or younger than 7 years. This is a prospective nonrandomized case series study was conducted. A total of 38 patients (total of 60 limbs: 36 varus and 24 valgus) were treated by percutaneous low-energy osteotomy and casting with shanz screws fixation and observed over 2-5 years. Clinical and radiological outcomes were evaluated at the end of follow-up period by standing scanogram which enabled tibiofemoral angles and the mechanical axis to be measured and the rate of complications. There was a statistically significant improvement of the radiographic parameters in the form of tibiofemoral angle and MAD. Clinically, all the cases were completely corrected just one patient (two limbs) complicated by over-correction but statically non-significant and. pin tract infection in shanz screws fixation was noticed in one Patient. Percutaneous low-energy osteotomy and casting with shanz screws fixation is a simple, safe, and effective method in dealing with 7 years and younger children with pathological knee deformities. Level of evidence: Therapeutic level IV.

Guided Growth for Correction of Elevated Tibial Posterior Slope in Pediatric ACL Deficiency: A Case Report

CASE

Fourteen-year-old boy, history of autism presented with bilateral knee instability. Imaging revealed bilateral anterior cruciate ligament (ACL) insufficiency, 20° of posterior tibial slope (PTS) on the right and 18° on the left. A guided growth technique using anterior placed tension band plates was used to correct the PTS. At 22 months, the PTS corrected to 5.5° on the right and 6° on the left. The patient's knee stability improved, and he resumed activities at 30 months.

CONCLUSION

Pediatric ACL insufficiency in the setting of elevated PTS can be successfully corrected with a guided growth technique.

The Effectiveness of Temporary Hemiepiphysiodesis for Non-idiopathic Coronal Angular Deformity of the Knee in Children: A Comparison of Hinge Eight-Plate and Traditional Eight-Plate

OBJECTIVE

Temporary hemiepiphysiodesis (TH) is a very common technique for coronal angular deformity of the knee in children, especially non-idiopathic. However, there is currently a dearth of comparative research on the hinge eight-plate (HEP) and traditional eight-plate (TEP). This study aimed to assess the clinical effectiveness and implant-related complication rates of TH using TEP and HEP for non-idiopathic coronal angular deformity, as well as to identify clinical factors affecting correction velocity.

METHODS

We retrospectively observed a consecutive series of patients with non-idiopathic coronal angular deformity of the knee who underwent TH using HEP or TEP and completed the deformity correction process from July 2016 to July 2022. According to the kind of eight plates, we divided those patients into the HEP group and the TEP treatment group. Relevant clinical factors, including the mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), screw divergence angle (SDA), angle of plate and screw (APS), hinge angle of HEP (HA), and the knee zone location of the lower extremity mechanical axis, were documented. Additionally, deformity correction velocity, complications, and clinical efficacy were assessed. Categorical variables were analyzed using the chi-squared test, Fisher exact test, or Wilcoxon test, while continuous variables were evaluated using the t-test or analysis of variance (ANOVA).

RESULTS

There were 29 patients in the HEP treatment group (seven girls and 22 boys) and 33 patients (12 girls and 21 boys) in the TEP treatment group. In all, 91.86% (79/86 knees) of the genu angular deformities were completely corrected, 6.98% (6/86 knees) had the overcorrection condition, and 10.47% (9/86 knees) had screw loosening. The swayback HEP rate was 11.29% (7/62 HEPs), which was related to the screw loosening in the HEP group (p < 0.001). The overall correction velocities and screw divergence angle change speeds in the HEP group were all significantly faster than those in the TEP group (p < 0.05). The initial APS of the HEP implanted was higher than that of TEP (p < 0.01), and multisite changes of APS during deformity correction of the HEP group were smaller than that of the TEP group.

CONCLUSION

HEP proved to be an appropriate device for TH for non-idiopathic coronal angular deformities of the knee with high correction velocity in children. Avoiding the occurrence of the swayback phenomenon may reduce the complications of HEP.

Factors influencing correction rate following hemiepiphysiodesis using tension band plates for deformities around the knee: a multivariate analysis study

PURPOSE

The aim of this study was to appraise various factors influencing the correction rate in temporary hemiepiphysiodesis (THE) around the knee joint. Specifically, the study analysed the relationship of correction rate with age, gender, aetiology, type and location of deformity.

METHODS

The retrospective study included children who underwent THE for a coronal plane deformity (genu valgus or varum) around the knee joint (distal femur or proximal tibia) over a ten year period (2010-2020). The primary outcome of interest was the correction rate of the deformity.

RESULTS

Thirty-three children (27 females and 6 males) with a mean age of 8.1 years involving 86 plates were included in the study. The mean correction achieved was 12.2° over a treatment period of 13.3 months. Subgroup analysis showed significant differences between the type (varus (0.8° per month), valgus (1.1° per month)) and the location of deformity femur (1.2° per month) and tibia (0.7° per month)]. On multivariate analysis, the location and the duration of treatment showed significant associations with the correction rate.

CONCLUSION

The correction of coronal deformities following temporary hemiepiphysiodesis is influenced by several factors. Valgus, femoral and deformities in younger children correct at a faster rate. Location of deformity and duration of treatment emerged as potential factors affecting the correction rate.

Factors Affecting Postoperative Courses After Removal of Transphyseal Screws Inserted for Correction of Genu Valgum

BACKGROUND

The aim of this study was to investigate factors determining the final outcomes of hemipercutaneous epiphysiodesis using transphyseal screw (PETS) for the genu valgum, especially focusing on postoperative courses after screw removal.

METHODS

Fifty-five patients with idiopathic genu valgum treated with hemi-PETS were included. The mechanical lateral distal femoral angle (mLDFA) and medial proximal tibial angle (MPTA) were measured to calculate the degree of correction and rebound. Regarding factors related to surgical techniques, the number of screw threads beyond the physis, the moment arm of the screw, and screw insertion angles were measured.

RESULTS

In 54 femoral segments (randomly selected in bilateral cases), hemi-PETS was performed with a growth remaining of 2.0±0.6 years. The screw was removed after 6.5±2.1 months, and the degree of correction was 5.0±1.5 degrees. The mean rebound angle was -0.4±2.4 (the negative value means further correction after screw removal). A late time of surgery and an extreme peripheral position of a screw were associated with the growth inhibition. In 50 tibial segments (also randomly selected in bilateral cases), a screw was inserted with a growth remaining of 2.0±0.6 years and removed after 6.3±1.9 months. The degree of correction was 2.9±1.7 degrees during the interval, and the rebound angle was 0.8±1.7 degrees. An earlier time of surgery and a greater correction angle before screw removal were associated with the rebound phenomenon.

CONCLUSIONS

Growth inhibition of >1.6 degrees was observed in about one-fourth of femoral segments. An extreme peripheral position of a screw should be avoided when performing hemi-PETS at the distal femur. We also recommend not performing hemi-PETS at distal femur with too short a period of growth remaining.

LEVEL OF EVIDENCE

Level III-retrospective comparative series.

An Innovative Plate Concept for Rotational Guided Growth: A Porcine Pilot Study

Background Rotational deformities in children are currently treated with an osteotomy, acute de-rotation, and surgical fixation. Meanwhile, guided growth is now the gold standard in pediatric coronal deformity correction. This study aimed to evaluate the feasibility of a novel implant intended for rotational guided growth (RotOs Plate) in a large porcine animal model. Methodology A submuscular plate was inserted on the medial and lateral aspect of the distal femoral physis of the left femur in 6 pigs. Each plate was anchored with a screw in the metaphysis and epiphysis respectively. The plates were expected to rotate the femur externally. The right femur acted as a control in a paired design. The animals were housed for 12 weeks after surgery. MRI scanning of both femora was performed before euthanasia after 12 weeks. Rotation was determined as the difference in the femoral version on MRI between the operated and non-operated femur after 12 weeks. Results External rotation in all operated femurs was observed. The mean difference in the femoral version on MRI between operated and non-operated femurs was 12.5° (range 9°-16°). No significant changes in axial growth were detected. Conclusions This study shows encouraging results regarding rotational guided growth, which may replace current invasive surgical treatment options for malrotation in children. However, further studies addressing potential secondary deformities are paramount and should be carried out.

Robot-assisted Temporary Hemiepiphysiodesis With Eight-plates for Lower Extremity Deformities in Children

PURPOSE

This study was performed to compare the radiographic results of robot-assisted and traditional methods of treating lower extremity deformities (LEDs).

METHODS

From January 2019 to February 2022, 55 patients with LEDs were treated by temporary hemiepiphysiodesis with eight-plates. They were divided into a robot group and a freehand group. The fluoroscopy time and operation time were recorded. The accuracy of screw placement was measured after the operation using the following parameters: coronal entering point (CEP), sagittal entering point (SEP), and angle between the screw and epiphyseal plate (ASEP). The limb length discrepancy (LLD) and femorotibial angle (FTA) were measured before the operation, after the operation, and at the last follow-up. Patients were followed up for 12 to 24 months, and the radiographic results of the 2 groups were compared.

RESULTS

Among the 55 patients with LEDs, 36 had LLD and 19 had angular deformities. Seventy-six screws were placed in the robot group and 85 in the freehand group. There was no difference in the CEP between the 2 groups ( P >0.05). The robot group had a better SEP (2.96±1.60 vs. 6.47±2.80 mm) and ASEP (3.46°±1.58° vs. 6.92°±3.92°) than the freehand group ( P <0.001). At the last follow-up, there was no difference in the LLD or FTA improvement between the two groups ( P >0.05). The incidence of complications was significantly lower in the robot group than in the freehand group (0/27 vs. 5/28, P <0.05).

CONCLUSION

Robot-assisted temporary hemiepiphysiodesis with eight-plates is a safe and effective method for treating LEDs in children. Robotic placement of screws is superior to freehand placement with respect to the entering position and direction. Although the correction effect for LLD and angular deformity is similar, screw dislocation is less common when using robot assistance.

LEVELS OF EVIDENCE

Level-III. Retrospective comparative study.

Effective time, correction speed and termination time of hemi-epiphysiodesis in children

In children with asymmetric growth on the medial and lateral side of limbs, if there still remains growth potential, the guided growth technique of hemi-epiphysiodesis on one side of the epiphysis is recognized as a safe and effective method. However, when the hemi-epiphysiodesis start to correct the deformities, how many degrees could hemi-epiphysiodesis bring every month and when to remove the hemi-epiphysiodesis implant without rebound phenomenon are still on debate. This article reviews the current studies focus on the effective time, correction speed and termination time of hemi-epiphysiodesis.

Isolating factors for the prediction of rebound after guided growth with tension band plating for the valgus deformity of the knee

Purpose

The conditions leading to growth rebound after hemiepiphysiodesis are still poorly understood. This article analyzes the radiographical outcomes after guided growth with tension band plating, using plates in idiopathic genu valgum patients and attempts to generate a predictive model of growth rebound.

Methods

Patients with idiopathic genu valgum deformity who received tension band plating were selected for evaluation. We only analyzed coronal plane deformities. Only patients with a long-standing X-ray before tension band plating surgery, a long-standing X-ray at tension band plating removal, and a long-standing X-ray at the latest follow-up after tension band plating removal were considered for this study. The change of mechanical axis deviation between the tension band plating removal and the last follow-up was evaluated for rebound, and ordinal logistic regression was performed to determine the relevant variables for predictive modeling rebound growth.

Results

Overall, 100 patients (189 legs) were analyzed. The mean mechanical axis deviation at tension band plating removal was 8.4 mm in varus direction, and the mean mechanical axis deviation at the last follow-up was -3.4 mm (p ≤ 0.001). However, 111 legs (59%) showed rebound growth, 57 (30%) stayed stable, and 21 (11%) showed a continuous correction. Six significant factors significantly influencing rebound were isolated which are clinically relevant: sex, age, baseline mechanical axis deviation, mechanical lateral distal femoral angle, and mechanical medial proximal tibial angle, and mechanical axis deviation correction rate. Mechanical axis deviation correction rate had the highest odds ratios. The machine learning classification model for predicting rebound growth built from the study data showed a misclassification rate of 39%.

Conclusion

There was a high rate of rebound growth in this cohort, especially for patients at a young age at implantation. The highest risk factors for rebound growth were male sex, and high correction rates, such as found during peak growth spurt. The proposed classification model needs more data to improve its predictive power before it can be used in clinics.

Level of evidence

Level III.

Does the Sleeper Plate Application for Temporary Epiphysiodesis Make Life Easier or Complicated? Increased Risk of Tethering

BACKGROUND

The present study aims to investigate the frequency of recurrence and tethering effect after only metaphyseal screw removal (sleeper plate technique) compared with the conventional complete plate removal in the treatment of lower extremity deformities with guided growth surgery.

METHODS

Seventy-two patients (107 limbs) treated by an 8-plate hemiepiphysiodesis technique around the knee joint were evaluated. After the desired correction, only metaphyseal screw was removed (sleeper plate group) in 35 limbs (25 patients), whereas both screws and plate were removed (plate removal group) in 72 limbs (47 patients). An increase of 5 degrees or more in joint orientation angles in the direction of the initial deformity was considered as recurrence. The rate of rebound, tethering, and maintenance of correction in groups was analyzed at the latest follow-up (mean of 49 mo).

RESULTS

The mean age of the patients was 97 months (range: 80 to 129 mo) at the time of index surgery. After a mean of 49 months (range: 16 to 86), 17 (48.5%) limbs maintained the desired stable correction in the sleeper plate group compared with 59 stable limbs (72.2%) in the plate removal group ( P <0.001). There was no statistically significant difference regarding recurrence between the sleeper plate group and the plate removal group (34.3% vs. 27.8%, respectively) ( P =0.216). Reinsertion of the metaphyseal screw was possible 8/12 limbs, and the remaining 4 limbs underwent further surgeries. There were 6 limbs (17.3%) of tethering in the sleeper plate group, and 4/6 limbs required further corrective surgeries. The remaining 2 limbs with slight tethering did not require further surgeries.

CONCLUSIONS

Removing only metaphyseal screw increases the risk of tethering. In addition, reinsertion of the screw may not be possible in all cases due to bony growth, and further corrective surgeries may be necessary. Close follow-up is required if the sleeper plate technique is to be applied.

LEVEL OF EVIDENCE

Level III.

Faster Rate of Correction with Distal Femoral Transphyseal Screws Versus Plates in Hemiepiphysiodesis for Coronal-Plane Knee Deformity: Age- and Sex-Matched Cohorts of Skeletally Immature Patients

BACKGROUND

Hemiepiphysiodesis (guided-growth) procedures have become the primary method of treatment for coronal-plane knee deformities in skeletally immature patients. Two leading techniques involve the use of a transphyseal screw or a growth modulation plate. However, clinical references for the estimation of correction are lacking, and no consensus has been reached regarding the superiority of one technique over the other. Therefore, the purpose of this study was to compare the rates of correction for distal femoral transphyseal screws and growth modulation plates in age- and sex-matched cohorts with coronal deformities.

METHODS

Thirty-one knees were included in each cohort on the basis of propensity scoring by chronological age and sex, and radiographic images were retrospectively reviewed preoperatively and postoperatively. Each case was measured for limb length, mechanical axis deviation (MAD), mechanical lateral distal femoral angle (LDFA), and bone age.

RESULTS

Both the MAD and LDFA rate of correction significantly differed between the screw and plate cohorts. The MAD rate of correction was observed to be 0.42 ± 0.37 mm/week (1.69 mm/month) in the plate cohort and 0.66 ± 0.51 mm/week (2.64 mm/month) in the screw cohort. The LDFA rate of correction was observed to be 0.12° ± 0.13°/week (0.50°/month) in the plate cohort and 0.19° ± 0.19°/week (0.77°/month) in the screw cohort.

CONCLUSIONS

The current study provides simple clinical references for the rate of correction of MAD and the LDFA for 2 methods of hemiepiphysiodesis. The results suggest that transphyseal screws may correct coronal knee deformities during the initial treatment stage more quickly than growth modulation plates in distal femoral guided growth.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Predicting Rates of Angular Correction After Hemiepiphysiodesis in Patients With X-Linked Hypophosphatemic Rickets

PURPOSE

Patients with X-linked hypophosphatemic rickets (XLH) often develop coronal plane knee deformities despite medical treatment. Hemiepiphysiodesis is an effective way to correct coronal plane knee deformities in skeletally immature patients, but a full understanding of the rate of angular correction after hemiepiphysiodesis in XLH patients, compared with idiopathic cases is lacking.

METHODS

We retrospectively reviewed charts of 24 XLH patients and 37 control patients without metabolic bone disease who underwent hemiepiphysiodesis. All patients were treated with standard-of-care medical therapy (SOC=active vitamin D and phosphate salt supplementation) in our clinical research center and had a minimum of 2-year follow-up after hemiepiphysiodesis. Demographic data as well as complications, repeat procedures, or recurrence/overcorrection were recorded. Standing lower extremity radiographs were evaluated before the surgical intervention and at subsequent hardware removal or skeletal maturity, whichever came first. Mean axis deviation, knee zone, mechanical lateral distal femoral angle (mLDFA), and medial proximal tibial angle were measured on each radiograph. The rate of angular correction was calculated as the change in mLDFA and medial proximal tibial angle over the duration of treatment.

RESULTS

The magnitude of the initial deformity of the distal femur was greater in XLH patients as compared with control for varus (XLH mLDFA 97.7 +/- 4.9 vs. Control mLDFA 92.0 +/- 2.0 degrees) and valgus (XLH mLDFA 78.7 +/- 6.2 vs. Controls mLDFA 83.6 +/- 3.2 degrees). The rate of correction was dependent on age. When correcting for age, XLH patients corrected femoral deformity at a 15% to 36% slower rate than control patients for the mLDFA (>3 y growth remaining XLH 0.71 +/- 0.46 vs. control 0.84 +/- 0.27 degrees/month, <3 y growth remaining XLH 0.37 +/- 0.33 vs. control 0.58 +/- 0.41 degrees/month). No significant differences were seen in the rate of proximal tibia correction. XLH patients were less likely to end treatment in zone 1 (55.0% XLH vs. 77.8% control). XLH patients had longer treatment times than controls (19.5 +/- 10.7 vs. 12.6 +/- 7.0 mu, P value <0.001), a higher average number of secondary procedures than controls (1.33 +/- 1.44 vs. 0.62 +/- 0.92 number of procedures), a higher rate of overcorrection than controls (29.2% vs. 5.4%), and a higher rate of subsequent corrective osteotomy than controls (37.5% vs. 8.1%). There was no significant difference in the rate of complications between groups (8.3% vs. 5.4%).

CONCLUSIONS

Patients with XLH undergoing hemiepiphysiodesis have a 15% to 36% slower rate of femoral deformity correction that results in longer treatment times, a higher likelihood to undergo more secondary procedures, and a lower likelihood to reach neutral mechanical alignment.

SIGNIFICANCE

This study provides important information to guide the timing and treatment of patients with XLH and coronal plane knee deformities. In addition, results from this study can be educational for families and patients with respect to anticipated treatment times, success rates of the procedure, complication rate, and likelihood of needing repeat procedures.

Temporary hemiepiphysiodesis using eight-plates for angular deformities of the lower extremities in children with X-linked hypophosphataemic rickets

PURPOSES

Temporary hemiepiphysiodesis (TH) using eight-plates is one of the most frequently performed surgeries for correcting angular deformities of the lower extremities in adolescents. Rarely have studies examined children with X-linked hypophosphataemic rickets (X-LHPR) treated with TH using eight-plates. This study was conducted to investigate the efficacy, the endpoint, and the complications of TH using eight-plates to correct angular deformities of the lower extremities in skeletally immature children.

METHODS

We reviewed a total of 26 children (86 physes, 52 knees) with X-LHPR (mean age of 6.2 years, range from 2 to 13 years) who underwent TH using eight-plate to correct angular deformities of the lower extremities. Radiographs and clinical records of these patients were evaluated for demographic data and related clinical factors.

RESULTS

The average correction of the mechanical lateral distal femoral angle (mLDFA) was 11.7 ± 8.7° (range from 1.0 to 29.7°), and the average correction of the mechanical medial proximal tibial angle (mMPTA) was 8.4 ± 5.0° (range from 0.3 to 16.7°). The mean deformity correction time was 22.7 months (range from 7 to 60 months), and the mean follow-up after eight-plate removal was 43.9 months (range from 24 to 101 months). Overall, 76.9% (20/26 patients) of the angular deformities of the knee were completely corrected and 15.4% (4/26) of the patients received osteotomy surgery. The femoral correction velocity (0.9° per month) was significantly higher than the proximal tibial (0.6° per month) (p = 0.02). The correction velocity of the mLDFA and mMPTA with the TH procedure was faster than that in the absence of intervention (0.9° vs. 0.2°, 0.7° vs. 0.4° per month, p < 0.05). The correction velocity of the mLDFA (1.2° vs. 0.5° per month, [Formula: see text]) and mMPTA (0.7° vs. 0.5° per month, p = 0.04) of patients whose age ≤ five years old was faster than that of patients whose age > five years old. A total of 69.2% (18/26) patients experienced one TH procedure using eight-plates only. Two patients had screw loosening (2/26, 7.7%). One patient (1/26, 3.8%) had a rebound phenomenon after the removal of eight-plate and had the TH procedure again. There was no breakage, infection, physis preclosure, or limited range of movement found in the follow-up.

CONCLUSION

TH using eight-plates is a safe and effective procedure with a relatively low incidence of complication and rebound, and it could be used as part of a streamlined treatment for younger X-LHPR patients with resistant or progressive lower limb deformity despite optimal medical treatment. Early intervention can achieve better results.

Guided growth for coronal lower limb deformities in skeletal dysplasia

Coronal angular deformities of the lower limbs are common in young children with skeletal dysplasia . The guided growth technique has been applied to correct deformities in children, but there are few comprehensive reports on the effectiveness of the procedure in skeletal dysplasia. We reviewed 44 limbs of 22 patients with various types of skeletal dysplasias who underwent guided growth surgery. Fifteen varus and 29 valgus limbs were treated with 102 epiphysiodesis. The average age at surgery, at implant removal, and at the latest examination was 10.4 ± 3.6 years, 11.8 ± 3.7 years and 14.1 ± 4.4 years, respectively. The mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (mMPTA), lateral distal tibial angle (mLDTA) and mechanical axis deviation (MAD) were measured from standing anteroposterior radiographs of both lower limbs. The mLDTA, mMPTA and MAD were successfully improved after surgery. Moderate or severe deformities were observed in 100% of the varus and 83% of the valgus limbs preoperatively, whereas only 14% of the varus and 20% of the valgus limbs had residual deformities at the latest examination. Correction of deformities was limited in some older children. Fifteen limbs (34%) required repeated implantations due to recurrence or inverted deformity. The guided growth surgery is effective in correcting coronal angular deformities in children with skeletal dysplasia with a limited risk of complications. The timing of surgery and implant removal is critical in obtaining satisfactory correction and preventing recurrence or inverted deformities.

Indications and Timing of Guided Growth Techniques for Pediatric Upper Extremity Deformities: A Literature Review

Osseous deformities in children arise due to progressive angular growth or complete physeal arrest. Clinical and radiological alignment measurements help to provide an impression of the deformity, which can be corrected using guided growth techniques. However, little is known about timing and techniques for the upper extremity. Treatment options for deformity correction include monitoring of the deformity, (hemi-)epiphysiodesis, physeal bar resection, and correction osteotomy. Treatment is dependent on the extent and location of the deformity, physeal involvement, presence of a physeal bar, patient age, and predicted length inequality at skeletal maturity. An accurate estimation of the projected limb or bone length inequality is crucial for optimal timing of the intervention. The Paley multiplier method remains the most accurate and simple method for calculating limb growth. While the multiplier method is accurate for calculating growth prior to the growth spurt, measuring peak height velocity (PHV) is superior to chronological age after the onset of the growth spurt. PHV is closely related to skeletal age in children. The Sauvegrain method of skeletal age assessment using elbow radiographs is possibly a simpler and more reliable method than the method by Greulich and Pyle using hand radiographs. PHV-derived multipliers need to be developed for the Sauvegrain method for a more accurate calculation of limb growth during the growth spurt. This paper provides a review of the current literature on the clinical and radiological evaluation of normal upper extremity alignment and aims to provide state-of-the-art directions on deformity evaluation, treatment options, and optimal timing of these options during growth.

Indications and timing in isolated medial femoral hemiepiphysiodesis for idiopathic genu valgum: A systematic review

INTRODUCTION

Temporary isolated medial femoral hemiepiphysiodesis (TIMFH) represents a safe and effective technique widely used to treat idiopathic genu valgum. Recent studies mainly concentrated on comparing outcomes of different implants, while less attention has been reserved to the proper indications and timing for surgery. The aim of this systematic review was to provide evidence-based guidelines about indications for device implant and removal and postoperative management.

METHODS

A comprehensive literature search was performed across three databases to select articles concerning TIMFH in the treatment of idiopathic genu valgum. Studies involving other etiologies or concomitant surgical procedures were excluded. Quality assessment of the included studies was conducted through the Newcastle-Ottawa Scale.

RESULTS

Ten studies involving 237 patients for a total of 446 knees were included in the analysis. Mean age at surgery was 11,4 years. Patients were considered for surgery using various clinical and radiological parameters. Intermalleolar distance (IMD) and mechanical lateral distal femoral angle (mLDFA) were the most common evaluated. Mean treatment time was 12 months. Rebound of the deformity occurred in 6,7% of cases.

CONCLUSION

Results of this review showed good consensus among authors. Patients undergoing TIMFH for IGV should be minimum 8 years old, with an IMD greater than 8 cm and a mLDFA lower than 87°. Postoperative management should comprise of quarterly clinic evaluations, and follow-up should last until skeletal maturity. The application of more uniform parameters in clinical practice may improve the establishment of the optimal timing for implant removal.

Natural behaviours after guided growth for idiopathic genu valgum correction: comparison between percutaneous transphyseal screw and tension-band plate

BACKGROUND

Percutaneous epiphysiodesis using a transphyseal screw (PETS) or tension-band plating (TBP) has shown favourable correction results; however, the physeal behaviours in terms of rebound, stable correction, or overcorrection after guided growth have not been completely understood. In patients with idiopathic genu valgum, we therefore asked: (1) How is the correction maintained after implant removal of guided growth? (2) Is there any difference in the natural behaviours after PETS or TBP removal at the femur and tibia?

METHODS

We retrospectively reviewed 73 skeletally immature limbs with idiopathic genu valgum treated with PETS or TBP. PETS was performed in 23 distal femurs and 13 proximal tibias, and TBP was performed in 27 distal femurs and ten proximal tibias. Mechanical axis deviation (MAD), mechanical lateral distal femoral angle (mLDFA), and mechanical medial proximal tibial angle were measured at pre-correction, implant removal, and final follow-up. Changes of ≤ 3° in mechanical angles after implant removal were considered stable. Comparisons between the implant, anatomical site, and existence of rebound were performed.

RESULTS

The mean MAD improved from - 18.8 mm to 11.3 mm at implant removal and decreased to -0.2 mm at the final follow-up. At the final follow-up, 39 limbs (53.4%) remained stable and only 12 (16.4%) were overcorrected. However, 22 limbs (30.1%) showed rebound. TBP was more common, and the correction period was longer in the rebound group (p < 0.001 and 0.013, respectively). In femurs treated with PETS, the mean mLDFA increased from 86.9° at implant removal to 88.4° at the final follow-up (p = 0.031), demonstrating overcorrection. However, a significant rebound from 89.7° to 87.1° was noted at the femur in the TBP group (p < 0.001). The correction of the proximal tibia did not change after implant removal.

CONCLUSION

The rebound was more common than overcorrection after guided growth; however, approximately half the cases demonstrated stable correction. The overcorrection occurred after PETS in the distal femur, while cases with TBP had a higher probability of rebound. The proximal tibia was stable after implant removal. The subsequent physeal behaviours after each implant removal should be considered in the guided growth.

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.

Rebound phenomenon and its risk factors after hemiepiphysiodesis using tension band plate in children with coronal angular deformity

BACKGROUND

This study was performed to evaluate the rebound phenomenon after the correction of coronal angular deformity by hemiepiphysiodesis using tension band plate in children and to identify its risk factors.

METHODS

We reviewed 50 children (mean age, 11.0 ± 2.5 years) with 94 physes who had undergone hemiepiphysiodesis using tension band plate due to coronal angular deformity of the lower limb. Patients' demographic data including sex, age at initial surgery and plate removal, affected bone (distal femur or proximal tibia), affected side, and body mass index were collected. The mechanical lateral distal femoral angle (mLDFA) and the mechanical medial proximal tibial angle (mMPTA) were measured from the teleradiogram, Physes were divided into rebound and non-rebound group, and rebound group was defined as the physes which had  ≥  5° of mLDFA or mMPTA returning to its original deformity. Generalized estimating equation based multivariable analysis was used to identify the risk factors for the rebound phenomenon after the deformity correction.

RESULTS

A total of 41 physes classified into rebound group and 53 physes into non-rebound group. There were significant differences in the age at initial surgery (p = 0.004), the age at implant removal (p = 0.002), the amount of correction (p = 0.001), and the rate of correction (p < 0.001) between two groups. The rate of correction was significantly associated with the rebound phenomenon (p = 0.044). The risk of rebound phenomenon was 1.2-fold higher as the rate of correction increased by 1° per year. The cutoff values of the correction rate between the two groups were 6.9°/year (p < 0.001).

CONCLUSIONS

This study showed that the rebound group had younger age and faster correction rate than those in the non-rebound group. In addition, the correction rate for deformity was a significant risk factor for the rebound phenomenon after hemiepiphysiodesis using the tension band plate. Close monitoring after implant removal is required for children who have a rapid correction rate over 7°/year.

Risk Factors for Rebound After Correction of Genu Valgum in Skeletal Dysplasia Patients Treated by Tension Band Plates

BACKGROUND

Growth modulation using tension band plates (TBPs) is increasingly important for lower limb deformity correction in patients with skeletal dysplasia (SKD). Development of rebound deformity is a concern after TBP removal. Data regarding this complication are rare; therefore, we evaluated the prevalence and risk factors for rebound deformity in children with SKD undergoing correction of genu valgum using TBP.

METHODS

All patients with SKD with genu valgum treated by TBP at the distal femur or/and proximal tibia at a single center were reviewed. Inclusion criteria were: (1) minimum 2-year follow-up after TBP removal or having revision surgery for rebound deformity and (2) implant removal age for girls 14 years and below and boys 16 years and below. Exclusion criteria were any femoral/tibial osteotomies during TBP treatment or follow-up. A change of ≥3 degrees of mechanical lateral distal femoral and/or medial proximal tibial angle was accepted as rebound deformity and analyzed statistically.

RESULTS

Thirty-three patients (59 limbs; 52 femur and 29 tibia physes) met our criteria. Mean follow-up after implant removal was 43.7 months. Rebound deformities were seen in 43 limbs (39 femurs and 13 tibias). Boys had more rebound than girls; however, this was not influenced by body mass index. Femurs had more rebound than tibias. Patients in the rebound group were younger than the nonrebound group. Time from application to removal of TBP was shorter in the rebound versus nonrebound group. Overcorrected limbs had more rebound deformity than not overcorrected. The difference in growth velocity of lower limbs in the rebound versus nonrebound group was statistically significant. Patients with epiphyseal dysplasia had more rebound than metaphyseal dysplasia, but this was not statistically significant.

CONCLUSION

Risk factors for developing a rebound deformity after correction of genu valgum using TBP in SKD included male sex, TBP surgery at a young age, short duration of TBP implantation, overcorrected extremity (mechanical axis deviation ≤1), and high percent growth velocity after TBP removal.

LEVEL OF EVIDENCE

Level IV-retrospective study.

Factors Affecting Rebound Phenomenon After Temporary Hemiepiphysiodesis and Implant Removal for Idiopathic Genu Valgum in Adolescent Patients

BACKGROUND

The aim of this study was to investigate factors determining postoperative courses, especially focusing on the rebound phenomenon, in adolescent patients with idiopathic genu valgum who underwent temporary hemiepiphysiodesis and implant removal.

METHODS

We identified and reviewed patients with idiopathic genu valgum treated with temporary hemiepiphysiodesis [using tension-band plates (plate group, PG) or transphyseal screws (screw group, SG)] and followed-up to skeletal maturity.

RESULTS

In our cohort [68 patients and their 68 limbs (randomly selected in bilateral cases)], the mean hip-knee-ankle alignment was -5.4±1.8 degrees at the time of temporary hemiepiphysiodesis (negative means valgus), 2.6±2.1 degrees at the time of implant removal, and 0.7±2.6 degrees at the last follow-up, respectively. Regarding the implants, the correction speed was not significantly different (P=0.192-0.315) between the PG (total 1.29±0.37 degrees/mo, 0.71±0.23 degrees/mo at distal femur, 0.59±0.16 degrees/mo at proximal tibia, n=19) and the SG (total 1.22±0.49 degrees/mo, 0.65±0.25 degrees/mo at distal femur, 0.57±0.23 degrees/mo at proximal tibia, n=49). The magnitude of rebound phenomenon in the PG (4.1±1.9 degrees) was greater (P<0.001) than that in the SG (1.1±3.1 degrees). The use of plates and faster correction speed, rather than more severe preoperative deformity or greater correction angle, were positively associated with the rebound phenomenon in regression analyses. Among the 68 knees, 1 showed valgus alignment ≥5 degrees and 5 showed varus alignment ≥5 degrees at the last follow-up. All the 6 cases were observed in the SG. Surgical wound dehiscence was observed in 1 patient in the PG.

CONCLUSIONS

The use of plates and faster correction speed were positively associated with the rebound phenomenon. Careful attention will be needed with the corresponding conditions for optimal results. Progressive genu varum after transphyseal screw removal, which was observed in this study, should be explored in future research.

LEVEL OF EVIDENCE

Level III-retrospective comparative series.

[Prevalence and predictors of rebound deformity in the frontal plane : A literature review]

The present literature review presents the current state of the art on the prevalence and causes of the rebound phenomenon after successful correction of leg axis deformity using temporary epiphysiodesis in children and adolescents. A total of 20 studies was included by three independent reviewers. The validity of most studies regarding the rebound incidence is limited by a non-standardized follow-up after plate removal, heterogeneous patient groups with a small number of cases, and missing information on the definition of rebound. The rebound incidence in studies without fundamental limitations in study design is on an average about 50% and underlines the clinical relevance of the topic. Only four studies reported reasons or risk factors for the occurrence of a rebound. In particular, a young age at the beginning of treatment with high residual growth potential after implant removal represents an increased rebound risk, which can be minimized by appropriate overcorrection of the leg axis.

Outcomes of Temporary Hemiepiphyseal Stapling for Correcting Genu Valgum in Children with Multiple Osteochondromas: A Single Institution Study

Background: Multiple osteochondromas is a rare skeletal disorder characterized by the presence of osteocartilaginous protrusions causing bony deformities, especially around the knee. Guided growth by temporary hemiepiphyseal stapling is the treatment of choice to correct the deformity by modulating the residual physeal growth of the lower limbs. Although this procedure is increasingly practiced, inconclusive evidence exists regarding its effectiveness in children with multiple osteochondromas. The study aims to compare the outcomes of temporary hemiepiphyseal stapling for correcting genu valgum in children with multiple osteochondromas vs. idiopathic cases. Methods: In this retrospective cohort study, we included patients admitted at a single institution from 2008 to 2018. A total of 97 children (77 idiopathic, 20 multiple osteochondromas) were enclosed, accounting for 184 limbs treated by temporary hemiepiphyseal stapling. We investigated if children with multiple osteochondromas had a similar successful rate of correction, rate of complications, and correction velocity compared to children with idiopathic genu valgum. Results: Overall, 151 limbs (82%) achieved complete correction or overcorrection, with idiopathic cases having a significantly higher rate of success compared to pathologic cases (88% vs. 55%; p < 0.001). In addition, multiple osteochondromas children sustained a higher rate of major complications (p = 0.021) and showed significantly lower correction velocity (p = 0.029). Conclusion: Temporary hemiepiphyseal stapling is effective in both idiopathic and multiple osteochondromas children, although the latter often achieved incomplete correction, had a higher risk of complications, and required a longer time of stapling. We suggest to anticipate the timing of intervention; otherwise, children with multiple osteochondromas and severe valgus deformity, approaching skeletal maturity, could undergo combined femoral and tibial stapling.