Efficacy and Safety of “Sleeper Plate” in Temporary Hemiepiphysiodesis and the Observation of “Tethering”

Abstract

Background: Guided growth is commonly performed by placing an extraperiosteal 2-hole plate across the growth plate with one epiphyseal and one metaphyseal screw. Recent studies investigated the efficacy of the removal of the metaphyseal screw only (sleeper plate) after correction. They concluded the practice to be unnecessary as only 19% of patients showed recurrence of deformity. This study aims to examine the incidence of rebound and undesired bony in-growth of the plate (tethering) after metaphyseal screw removal only. Methods: In this retrospective case series, patient data on 144 plates inserted around the knee were obtained. Plates still in situ (n=69) at the time of study and full hardware removal (n=50) were excluded. The remaining 25 plates had only the metaphyseal screw removed after completed deformity correction. We analyzed the rate of tethering, rebound, and maintenance of correction in 2 age groups at latest follow (mean of 3.5 y). The Fisher exact test with Freeman-Halton extension was used to analyze categorical data and the Student t test for descriptive variables. Results: Twenty-five plates were identified as “sleeper plates” in our series. Thirteen plates (52%) maintained the achieved correction after a mean of 21 months (range: 4 to 39 mo), 9 plates (36%) required screw reinsertion due to rebound after a mean of 22 months (range: 12 to 48 mo) from screw removal, and 4 plates (16%) showed tethering with undesired continuation of guided growth after a mean of 14 months (range: 7 to 22 mo) from screw removal. Younger patients (<8 y at time of plate insertion) had higher rates of rebound and tethering (P=0.0112, Fisher exact test). All tethering occurred in titanium plates, none occurred in steel plates. Conclusions: The sleeper plate is an acceptable treatment strategy for coronal deformities around the knee, however, tethering and rebound may occur, especially in younger patients. Titanium plates may increase the risk of tethering, however, further long-term follow-up is needed as there were only 6 steel plates versus 19 titanium in this study. We stress the importance of close postoperative follow-up to identify signs of tethering and rebound early to prevent over-correction. Level of Evidence: Level IV—retrospective case study.

Efficacy and Safety of “Sleeper Plate” in Temporary Hemiepiphysiodesis and the Observation of “Tethering”: Are the Benefits Worth the Risks?

“…They note a 22% rate of rebound requiring replacement of the screw, and 2 complications (1 soft tissue irritation, 1 progression of angular deformity), both of which required unplanned surgery. Taken together, these 2 studies2,3 and that of the authors1 show the common theme of complications of this technique and the need for unnecessary surgery. With this information, removal of only the metaphyseal screw seems to be high risk, low reward, and should not be recommended for routine use based on the available evidence.…”

“…I do appreciate that the authors acknowledge the potential complications of removing only the metaphyseal screw 1. Concerns regarding the possibility of harm using this technique have been raised previously in at least 2 studies 2,3.…”

“…I read with interest the article entitled “Efficacy and Safety of ‘Sleeper Plate’ in Temporary Hemiepiphysiodesis and the Observation of ‘Tethering’.”1 With respect to the authors, I believe they are drawing the wrong conclusions from their results.…”

“…In 25 children, at the time of deformity correction only the metaphyseal screw was removed, leaving the plate and epiphyseal screw in place, the so called “sleeper plate.” Thirty-six percent of these patients required replacement of the metaphyseal screw due to rebound, 16% developed tethering and deformity progression, and all patients, including those that did not require metaphyseal screw reinsertion, underwent routine implant removal at skeletal maturity. They conclude that removal of the metaphyseal screw is an acceptable strategy in growing children 1…”

What’s New in Limb Lengthening and Deformity Correction

“…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 .…”