The fate of hemiepiphysiodesis implants left in place after skeletal maturity in patients with idiopathic genu valgum.

Hemiepiphysiodesis using tension band plate and screws is a frequently used technique for the correction of lower extremity angular deformities. These implants are often left in place if patients have corrected their alignment on reaching skeletal maturity. There is little information regarding the rate of and reasons for subsequent removal of these deep implants. This retrospective case-control study included patients treated with hemiepiphysiodesis with tension band plate and screws at the distal femur and/or proximal tibia for idiopathic genu valgum and reached skeletal maturity with implants retained. Electronic medical records and radiographs were reviewed for patient characteristics and the need for subsequent removal of implants. Those who had implants removed were compared to those with implants not removed using Student's t-test for continuous variables and chi-square for categorical variables. Forty-six patients met inclusion criteria. Twenty-five of 46 patients (54%) underwent subsequent removal of deep implants, and all cases were due to symptoms related to the plate and screws. Factors associated with removal of deep implants included multiple vs. single rounds of hemiepiphysiodesis (76% vs. 43%, P = 0.02) and plates at the distal medial femur alone (P = 0.004). There were no differences between groups regarding sex, age at hemiepiphysiodesis, height, weight, and BMI. In conclusion, after skeletal maturity, there was a 54% rate of removal of symptomatic hemiepiphysiodesis implants. Factors associated with implant removal include repeat hemiepiphysiodesis and isolated distal medial femur plate position. This information can be used to guide patient and provider expectations as patients transition to adulthood.