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

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.

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.

Transphyseal Hemiepiphysiodesis: Is it Truly Reversible?

BACKGROUND

Although numerous studies reported the efficacy of percutaneous epiphysiodesis using transphyseal screws (PETS) in correcting angular knee deformities, many surgeons refrained from using it in younger children because of a lack of objective evidence of reversibility. Our hypothesis is that PETS is both truly reversible and effective.

METHODS

Twenty-one patients aged 8 to 13 years (36 lower limbs LL) with coronal plane knee deformity were enrolled into this prospective case series from January 2021 to September 2023. Besides the routine monitoring of PETS efficacy, low dose CT knee of 32 treated physes was done 6 months after screw removal. In addition, lower limb length, mechanical lateral distal femur angle (mLDFA), and medial proximal tibial angle (MPTA) were recorded preoperatively and 6 to 17 months after screw removal for 24 LL to investigate physis behavior, technique reversibility, and resumption of bone growth after screw removal.

RESULTS

The mean mechanical axis deviation (MAD) correction rate was 3.46 mm/mo and 1.78 mm/mo for genu valgum and genu varum patients, respectively. No physeal bony bars could be detected 6 months after screw removal for all patients. Out of 24 physis that underwent computerized radiography (CR) of the whole lower limb, 12 LL resumed their growth, 4 were stationary, while 8 were excluded due to inadequate calibration. A single physis showed rebound deformity, and another showed overcorrection in the genu valgum group.

CONCLUSIONS

In addition to being a highly effective method of hemiepiphysiodesis, PETS was found to be reproducible, safe, and reversible when used in the juvenile and early adolescent pediatric population.

LEVEL OF EVIDENCE

IV-Prospective case series.

What's new in pediatric lower limb reconstruction?

The last years brought many advances relevant to lower limb reconstruction. It feels like guided growth has been looked at from every angle, and still there are new emerging concepts like rotational guided growth waiting to be validated. New hexapod external devices are more accurate and easier to use, and new unilateral fixators allow for more versatile and stable fixation and lengthening. Intramedullary nail lengthening has found its place as a standard procedure for various diagnoses in children and young adults. First results of new and exciting approaches like extramedullary implantable nail lengthening and lengthening plates have been reported. Pharmaceutical treatment has changed the course of certain diseases and must be integrated and considered when making a reconstructive treatment plan. As reconstructive surgery is rapidly advancing so are the technical options for prosthetic fitting, which makes it difficult for caregivers as well as for parents to make the decision between reconstruction and amputation surgery for the most severe cases of congenital deficiencies. This review is highlighting new developments of lower limb reconstruction and is reviewing the current literature.

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.

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.