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.

Skeletal dysplasias (SkD) are a rare group of disorders characterized by abnormal growth and development of bone and cartilage, often causing limb deformity. Many patients also have ligamentous instability that can accentuate the malalignment. This ligamentous instability can present either a generalized ligamentous laxity or focal coronal plane intra-articular malalignment. Temporary hemiepiphysiodesis (HE) is a commonly employed minimally invasive surgical technique for correcting coronal plane limb deformities. This study evaluated the effectiveness of HE in the correction of knee coronal plane deformity in children with SkD and the correlation of concurrent joint laxity.

A retrospective cohort study was conducted to evaluate radiological outcomes of HE for coronal plane knee deformities in patients with SkD (aged <18 years) who had surgery between January 1, 2008 and December 31, 2020. Changes in distal femoral and proximal tibial mechanical angles, and knee joint line congruence angles (JLCA) prior to HE and at the final follow-up were analyzed. An increased JLCA of ≥±2° was considered a knee with ligamentous instability. Preoperative and postoperative patient-reported pain status was recorded.

Fifty-six tibial and 42 femoral HE procedures in 32 children (mean age at HE: 9.8 ± 2.8 years) were included. The deformity was fully corrected in 23/32 (72%) children, at an average annual rate of 6.3° at the distal femur and 3.3° at the proximal tibia, over 21.9 ± 12.6 months. The overall pre-HE JLCA improved by an average of 5.3° (P < .05). The improvement was more pronounced in varus knees (n = 45; P < .05) than valgus knees (n = 12; P = .11) but regardless of the severity of joint instability, pre-HE JLCA did not impede the rate of femoral (r = -0.22) or tibial (r = -0.21) corrections. Preoperative pain was reported by 78% of patients whereas only 25% of patients reported pain postoperatively at the final follow-up (mean follow-up: 26.4 ± 13.5 months).

The presence of coronal plane intra-articular malalignment did not affect the rate and the magnitude of correction with HE in this cohort. Coronal plane deformities and JLCA improve with deformity correction by HE in children with SkD.

(1)Intra-articular malalignment at the knee does not impede the success of hemiepiphysiodesis in children with skeletal dysplasia.(2)While all coronal plane knee deformities improved, a more significant improvement was noted in children with varus than valgus.(3)Joint line congruency angles improved with guided growth for coronal plane deformities.

III.

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.

Tension band plating is widely used in the surgical treatment of coronal plane deformities around the knee. The rebound phenomenon after implant removal is a common complication of this technique. Overcorrection of joint orientation angles is a method to minimize the effect of the rebound phenomenon. This study aims to investigate the natural course of overcorrected joint orientation angles after plate removal in patients with genu valgum deformity.

Patients who underwent hemiepiphysiodesis with tension band plating due to genu valgum deformity between 2010 and 2019 were retrospectively analyzed. Mechanical lateral distal femoral angles (mLDFA) and mechanical medial proximal tibial angles were calculated before plate application, before implant removal, and at the last follow-up. At the implant removal, mLDFA>90 degrees and mechanical medial proximal tibial angles <85 degrees were accepted as overcorrected.

Seventy-two segments from 45 patients were included. For femoral valgus deformities (n=59), the mean mLDFAs at index surgery, implant removal, and the last follow-up were 79.8±3.9 degrees, 95.5±3.7 degrees, and 87.3±5.1 degrees, respectively. In the more and less than 10 degrees rebound groups, the median age of patients at index surgery were 66 and 101 months (P=0.04), the mLDFA during implant removal were 97.8 degrees and 94.4 degrees (P=0.005), and the mean amount of correction in mLDFA was 17 degrees and 13 degrees (P=0.001), respectively. At the last follow-up, joint orientation angles were found to be still overcorrected in 16 (22%), within normal limits in 36 (50%), and undercorrected in 20 (28%) segments. Ten (13%) segments required additional surgery due to residual deformity.

Overcorrection with tension band plating is an effective modality in the treatment of genu valgum deformity. Rebound after plate removal increases as the age at index surgery decreases and the amount of conscious overcorrection increases. Most segments return to normal joint orientation angle limits after overcorrection. We recommend a mean of 5 degrees routine overcorrection in patients with genu valgum deformity to overcome the rebound phenomenon and to make future interventions easier if ever needed.

Level III.

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.

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.

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.

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.

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.