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

Abstract

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 followup, 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.

Faster Rate of Correction with Distal Femoral Transphyseal Screws Versus Plates in Hemiepiphysiodesis for Coronal-Plane Knee Deformity

“…Baghdadi et al reported 0.52°/month with plates 30 . In studying valgus deformity, Ko et al observed that screws achieved 0.65° ± 0.25°/month and plates, 0.71° ± 0.23°/month, but the plate group showed greater occurrence of rebound while the screw group showed progressive genu varum after implant removal 31 . Park et al reported a rate of correction of 0.92°/month with screws and 0.64°/month with plates 18 .…”

“…Recent studies of unmatched cohorts have suggested that screws may effect change more rapidly 18,20,21 . The authors of another study disagreed 31 ; however, that study did not observe MAD as an outcome. Since the first use of TS and GMP in studies published in 1998 3 and 2007 2 , respectively, much of the literature suggests that postoperative complications appear similar between the 2 methods 5-12 .…”

The Fate of Overcorrection After Hemiepiphysiodesis in Valgus Deformities Around the Knee

“…Deformity recurrence after implant removal, or the so-called rebound phenomenon, is a highly expected complication in the correction of the coronal plane deformities of the knee. 5 Although there is no uniform definition for this phenomenon, risk factors associated with deformity recurrence were studied in several publications [3][4][5]7,[13][14][15][16] proper methods to overcome this and their outcomes, however, were poorly investigated.…”

What’s New in Limb Lengthening and Deformity Correction

“…Male gender, a younger age at the time of the surgical procedure, a shorter duration of retention of implants, and overcorrection of deformity were identified as risk factors for the occurrence of rebound deformity of at least 3° in patients with genu valgum due to skeletal dysplasia who were treated with tension band plates 55 . The results of another study revealed a higher incidence of rebound with faster correction speeds and following tension band plating for growth modulation compared with transphyseal screw hemiepiphysiodesis 56 . Gerges et al reported a 36% rebound rate and a 16% incidence of tethering and undesired continuation of growth modulation in a cohort of patients in whom a guided-growth implant for angular deformity correction around the knee had been converted to a sleeper plate by removal of the metaphyseal screw 57 .…”