Hemiepiphysiodesis for Lower Extremity Coronal Plane Angular Correction in the Distal Femur and Proximal Tibia in Children With Achondroplasia

Abstract

Background: Achondroplasia is the most prevalent form of skeletal dysplasia, affecting more than 250,000 individuals. Lower extremity angular deformities, particularly genu varum, are common in children with achondroplasia, often resulting in pain and limitation of function. The authors aim to determine the utility of lower extremity growth modulation with hemiepiphysiodesis in children with achondroplasia for correction of coronal plane deformities about the knee. Methods: The authors performed a retrospective chart review of a single center from 1/1/2000 to 12/31/2020 to identify pediatric patients with achondroplasia treated with hemiepiphysiodesis as their initial procedure at the distal femur and/or proximal tibia. Patients with adequate records and who had completed their treatment were included. Data collected included duration of treatment, complications, need for osteotomy, and radiographic measurements including initial and final mechanical axis deviation, knee mechanical axis zone, mechanical lateral distal femoral angle and medial proximal tibia angle. Results: Ten patients with 17 limbs met our criteria. Nine patients (15 limbs) were treated for genu varum and 1 patient (2 limbs) was treated for genu valgum. Prior to treatment, the mechanical axis fell in zone 3 in 59% of limbs and zone 2 in 41%. Average correction in mechanical axis deviation was 26.1 mm. Average change in mechanical lateral distal femoral angle was 10.3 degrees per limb, and average change in medial proximal tibia angle was 7.1 degrees per limb. Average treatment duration was 909 days. At final follow up, 81% (14/17) of limbs had the mechanical axis in zone 1, with the remaining 18% (3/17) in zone 2. No patient/limb underwent subsequent distal femur or proximal tibia osteotomy for coronal plane alignment. Conclusions: Children with achondroplasia can successfully be treated with hemiepiphysiodesis to correct coronal plane deformities at the distal femur and proximal tibia. Using this technique, no patient in our series required an osteotomy for genu varum/valgum. Level of Evidence: Therapeutic level IV, Case series.

Do Patient Sex and Age Affect Hemiepiphysiodesis Outcomes?

“…Hemiepiphysiodesis is an acknowledged, minimally invasive, effective method of treatment for genu valgum and varum deformity correction in pediatric patients [ 1 , 2 , 3 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 21 , 22 , 23 ]. Previous studies focused either on the clinical and radiographic outcomes of hemiepiphysiodesis [ 1 , 2 , 3 , 9 , 10 , 11 , 12 , 13 , 18 , 21 , 22 , 23 , 24 ] or on the effects of the type of implants used [ 6 , 8 , 20 ]. However, the question of a potential impact of patient age and sex on hemiepiphysiodesis outcomes was not explored.…”

“…Another group of 26 patients had a mean deformity correction time of 22.7 months [ 23 ]. Makarewich et al reported removing implants in 10 patients after hemiepiphysiodesis after a mean of 30.3 months postoperatively [ 24 ]. In our patient population, we observed that patient sex affected deformity correction time, with the time being longer in females; whereas patient age at the time of surgery seemed to be of no consequence for this parameter.…”

“…Pediatric lower limb deformities are a considerable problem for orthopedic surgeons [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Genu valgum or varum may cause limping, pain, knee or patellar instability, gait disturbances, limited mobility, articular cartilage damage, accelerated joint degeneration, rapid fatigue, sports and physical activity limitations, meniscal injury, and cosmetic concerns [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 24 ]. Genu valgum or varum deformity treatment is indicated in cases with a mechanical axis deviation (MAD) of >10 mm or the inter-malleolar distance of >8 cm, or an angular deformity of >10° [ 1 , 3 , 7 , 11 , 12 , 14 , 16 ].…”

“…Since conservative treatment methods (rehabilitation, exercises, insoles, orthoses, plaster casts) for pediatric lower limb deformities are ineffective, surgical treatment is recommended in this patient population [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 17 , 22 , 23 ]. The techniques of pediatric lower limb deformity correction include the Ilizarov method osteotomy, osteotomy with plate fixation, osteotomy with external fixation, and hemiepiphysiodesis with the use of stapling or an O-plate (also known as an eight-plate) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Hemiepiphysiodesis is indicated for smaller deformities (less than 11 degrees) and in patients aged approximately 0.5–2 years prior to the predicted growth plate fusion or at an age of 14–16 years [ 6 , 7 , 8 , 10 , 11 , 14 ].…”

“…Little is known of the potential effects of patient sex and age on hemiepiphysiodesis outcomes. Previous research focused on the clinical and radiological outcomes of hemiepiphysiodesis [ 1 , 2 , 3 , 4 , 9 , 10 , 11 , 12 , 13 , 18 , 19 , 21 , 22 , 23 , 24 ]; other authors compared the outcomes of this procedure depending on the implant type used [ 6 , 8 , 17 , 20 ]. Some literature reports suggest that effective hemiepiphysiodesis that ensures complete deformity correction requires the procedure to be performed approximately 0.5–2 years prior to the predicted growth plate fusion or at an age of 14–16 years, at the latest [ 6 , 7 , 10 , 14 ].…”