Removal of the Metaphyseal Screw From Tension Band Constructs After Hemiepiphysiodesis: High Rates of Physeal Tethering and Subsequent Implant Removal.

Background: Removal of the metaphyseal screw from tension band plate constructs after correction of angular deformity in patients treated with hemiepiphysiodesis has been suggested as an alternative to removing the plate and both screws. While this has the potential benefit of easier implant removal and reinsertion in the event of rebound, there is debate in the literature regarding the benefits and risks of leaving the epiphyseal screw and plate in place.

Methods: Patients treated with hemiepiphysiodesis at the distal femur and/or proximal tibia with tension band plates and screws who underwent subsequent removal of the metaphyseal screw after correction were included. Charts and radiographs were reviewed for the need for metaphyseal screw reinsertion, subsequent removal of deep implants, and evidence of physeal tethering. Tethering was defined as progressive overcorrection in the treated bone segment after removal of the metaphyseal screw with the mechanical axis moving one full mechanical axis zone or more. Patients with tethering were compared with those without.

Results: A total of 215 patients with 387 limbs treated met inclusion criteria. Of those, 175 patients were treated for idiopathic genu valgum, while 40 were treated for other conditions. Fifty-nine individuals (27%) underwent replacement of the metaphyseal screw for repeat angular correction. Fifty-one percent of patients underwent secondary procedures for reasons other than metaphyseal screw reinsertion (74 symptomatic implant removal, 7 elective implant removal, 29 due to tethering). There were 44 cases of tethering in 36 patients (17%). In cases of tethering, 7 patients were treated with observation, 11 with implant removal only, 16 with hemiepiphysiodesis on the opposite side, and 2 with osteotomy. Patients with tethering were significantly younger, more likely to be male, and more likely to have had the metaphyseal screw removed more than once (P < 0.05).

Conclusion: Removal of only the metaphyseal screw after hemiepiphysiodesis has high rates of tethering and further surgery for iatrogenic deformity correction and implant removal. This technique is not recommended.

Level of evidence: Therapeutic Level III, case-control study.