|Year : 2019 | Volume
| Issue : 1 | Page : 27-32
The “Sleeper” plate: A technical note
Muayad Kadhim1, Ahmed I Hammouda2, John E Herzenberg1
1 International Center for Limb Lengthening, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore, Baltimore, Maryland, USA
2 Department of Orthopaedic Surgery, Al-Azhar University Hospitals, Cairo, Egypt
|Date of Web Publication||23-Aug-2019|
Dr. John E Herzenberg
International Center for Limb Lengthening, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, Maryland 21215
Source of Support: None, Conflict of Interest: None
Context: A tension band plate (TBP) for guided growth of angular deformity is typically removed after the deformity is corrected to prevent overcorrection. After TBP removal, rebound deformity may occur, necessitating reinsertion of a new TBP. Aims: This study aims to describe a minimally invasive technique for partial removal of TBP to deactivate the TBP when correction is achieved. The technique also allows minimally invasive reactivation of the construct when desired. Settings and Design: This is retrospective case series study. Subjects and Methods: The surgery consists of removing the metaphyseal screw only and keeping the plate and the epiphyseal screw. The procedure is done through a 1-cm incision with fluoroscopy. The metaphyseal edge of the plate is elevated off the bone to break the seal between it and the bone, to prevent tethering. Bone wax is injected in the empty plate hole to prevent bone ingrowth, as this could also cause re-tethering. In case of a subsequent rebound deformity, the metaphyseal screw may be re-inserted percutaneously to reactivate (“wake-up”) the “sleeper plate”. Statistical Analysis Used: Descriptive analysis. Results: The sleeper plate technique was done in eight patients (three males and five females). Four patients had genu valgum and four had genu varum. Mean age at surgery was 11 years (7–14 years). Metaphyseal screw removal was done in a mean period of 14 months (range from 7.4 to 22 months) after the index procedure. Rebound of the deformity happened in three patients and required plate reactivation by reinsertion of the metaphyseal screw. Conclusion: The sleeper plate technique is a minimally invasive procedure and can be an alternative to the removal of the whole TBP construct if the patient is skeletally immature with a risk of deformity rebound.
Level of Evidence: IV
Keywords: Bone wax, growth modulation, guided growth, hemiepiphysiodesis, sleeper plate, tension band plates, tension band plate
|How to cite this article:|
Kadhim M, Hammouda AI, Herzenberg JE. The “Sleeper” plate: A technical note. J Limb Lengthen Reconstr 2019;5:27-32
| Introduction|| |
Lower extremity angular deformities in growing children can be managed with either bone osteotomy or growth modulation (“guided growth [GG]”). GG procedures can be accomplished using staples, transphyseal screws, or a tension band plate (TBP).,,,,, The concept of growth modulation is to temporarily inhibit physeal growth on the convex side of the deformity and to allow the physis on the concave side to gradually correct the deformity. Serial radiographs are important to monitor deformity correction and to avoid overcorrection.
Blount and Clarke reported using staples in children with tibia vara. Staples may cause damage to the growth plate at the site of insertion if the perichondrial ring of LaCroix is injured at the time of staple insertion or removal. In addition, staples are subject to migration and breakage.,, Stevens introduced the TBP, a nonlocking two-hole plate with screws on either side of the physis. TBPs have become widely used for angular deformities in children because of the ease and accuracy of insertion and resistance to spontaneous extrusion in young children, unlike staples.,,
The “rebound” phenomenon is a commonly encountered problem after the removal of a TBP., Recurrent deformity after TBP removal may necessitate repeat insertion of the TBP to correct the deformity again. The concept of partial TBP removal (metaphyseal screw removal) has recently gained popularity to halt the growth modulation effect of the TBP but maintain the plate and the epiphyseal screw in situ for future re-activation if needed. This strategy minimizes the trauma and magnitude of repetitive open surgeries to insert, remove, and reinsert the entire TBP.
TBPs are widely used at our institution to correct angular deformity in children. TBP removal is typically performed after deformity correction. If the patient is skeletally mature, the decision to remove the TBP is deferred to the patient and family if there is pain or hardware prominence. On the other hand, if the patient is still skeletally immature, the possibility of deformity rebound is discussed with families and they are asked to consider partial removal of the TBP (metaphyseal screw removal), particularly in cases in which the child is felt to be at high risk for rebound.
The aim of this study was to present a technique that the senior author has employed when rebound phenomenon was anticipated, by metaphyseal screw removal, and the technique to reactivate the TBP by reimplantation of the metaphyseal screw. The technique has been developed to prevent inadvertent retethering, which would lead to continue over correction.
| Subjects and Methods|| |
The sleeper plate technique was done in eight patients since 2012. We retrospectively reviewed the medical records after receiving an exemption letter from the institutional review board.
Surgical technique of percutaneous metaphyseal screw removal
Once the TBP has corrected the deformity, the patient is taken to the operating room. This procedure was done under image intensifier control through a 1-cm incision with no need of a tourniquet. A straight hemostat is used to dissect under fluoroscopic control down to the metaphyseal screw head. A small periosteal elevator is utilized to clean the scar tissue surrounding the metaphyseal screw head [Figure 1]a. A small curette is used to clean the screw head. For cannulated screws, a 1.5-mm guide wire may be inserted in the metaphyseal screw. The cannulated hex-driver is then applied over the wire to remove the screw. After removing the screw, the small periosteal elevator is used to gently elevate the metaphyseal end of the plate from the bone and the surrounding fibrotic scar tissue [Figure 1]b. This helps to “untether” the plate, which may otherwise continue to cause the GG effect by virtue of the metaphyseal end of the plate being tethered to the bone with scar tissue. It is easier to mobilize the plate if the epiphyseal screw is loosened by one or two turns. Once the metaphyseal screw is removed, there is a risk that the underlying metaphyseal bone could grow back into the empty screw hole of the TBP. In order to prevent this possible bone ingrowth into the empty hole of the TBP, 1 cc of surgical bone wax is injected into the hole with a tuberculin syringe [Figure 1]c. To facilitate visualization of the syringe by fluoroscopy, especially in obese patients, a 23- gauge needle is inserted and wrapped around the slip tip of the tuberculin syringe [Figure 2]. Simple wound closure with 4-0 Monocryl is done to close the wound. A gauze dressing and Tegaderm waterproof bandage are applied. Full weight bearing and return to activities are permitted.
|Figure 1: Metaphyseal screw removal from the tension band plates of the right distal femur. A small periosteal elevator is used to free the screw head (a). After screw removal, a periosteal elevator is used to elevate the plate from the bone (b). (c) shows a fluoroscopic image of bone wax injection into the plate hole after screw removal. Used with permission, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore|
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|Figure 2: The preparation of the tuberculin syringe to facilitate fluoroscopic visualization during bone wax injection. (a) An 18-gauge needle was inserted into the tuberculin syringe head and was bent to form a circle surrounding the syringe head. (b and c) The tuberculin syringe was filled with bone wax (by rolling a small piece of bone wax into the thin cylinder syringe). Used with permission, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore|
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Surgical technique of percutaneous metaphyseal screw re-insertion
In the event of rebound/relapse of the deformity, the patient is brought to the operating room. Metaphyseal screw re-insertion technique is presented in [Figure 3]. The surgery starts with imaging the metaphyseal hole of the TBP with cross-table lateral fluoroscopy. This is analogous to the “perfect circle” technique, commonly used for inserting interlocking screws into an intramedullary nail. Following that, a 1-cm incision is made, and then a straight hemostat is used to dissect the soft tissue down to the metaphyseal hole in the TBP. A 1.5-mm guide wire is inserted under fluoroscopic guidance through the metaphyseal hole of the plate (“perfect circles”). Next, a cannulated 3.2 mm drill bit is used to broach the cortex, no more than 5 mm deep. A cannulated 4.5-mm screw is then inserted over the guide wire. Alternatively, a solid screw can be inserted to increase the construct strength. In such cases, a cannulated screw is used to tap the screw path over the guide wire, the cannulated screw and the guide wire are removed, and a 4.5-mm solid screw is inserted through the metaphyseal hole of the TBP. To prevent the solid screw from getting lost in the soft tissue, especially in obese patients, an 0-vicryl suture is tied to the neck of the screw to secure it as an ersatz “capture” mechanism as described in the technique of submuscular plating for femoral shaft fractures.
|Figure 3: Reinsertion of the metaphyseal screw in the tension band plate of the distal femur. A 1.5-mm K-wire is used to identify the screw hole with fluoroscopic guidance (a). A 3.5-mm cannulated drill bit is used to create a path for the screw no more than 5-mm depth in the bone (b). A 4.5-mm cannulated screw is inserted over the guide wire to tap the screw trajectory (c). A 4.5-mm noncannulated screw is inserted after guide wire removal under fluoroscopy (d). Used with permission, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore|
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| Results|| |
The sleeper plate technique was done in 8 patients (3 males and 5 females) with 13 lower limbs (6 on the right and 7 on the left side) [Table 1]. Four patients had genu valgum (fibular hemimelia, congenital femoral deficiency, multiple hereditary exostoses, and idiopathic genu valgum) and four patients had genu varum (three had adolescent Blount disease and one had multiple epiphyseal dysplasia). Mean age at surgery was 11 years ranging from 7 to 14 years. Metaphyseal screw removal was done in a mean period of 14 months (range from 7.4 to 22 months). Deformity rebound happened in three patients, and therefore, metaphyseal screw re-insertion was done. We did not observe any case of loss of position or rotation of the retained TBP (after removal of the metaphyseal screw).
|Table 1: List of patients treated with TBP for lower extremity angular deformity who had metaphyseal screws removal strategy (Sleeper plate technique)|
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A 12-year-old obese male presented to the clinic with bilateral genu varum (adolescent Blount disease). The radiographic evaluation showed bilateral distal femoral and proximal tibial varus deformity [Figure 4]a. He was treated with bilateral distal femoral and proximal tibial lateral growth modulation using solid screws to increase the strength of the TBP construct. One year following the procedure, the patient achieved correction of the varus deformity on the right [Figure 4]b. We, therefore, removed the metaphyseal screw of the TBPs in the right distal femur and proximal tibia. After 16 months, the patient developed a recurrence of the varus deformity on the right side [Figure 4]c, and then the decision was made to re-insert the metaphyseal screw in each TBP. Eighteen months later, correction was achieved [Figure 4]d. The metaphyseal screws were then removed a second time.
|Figure 4: Radiographs of the right lower extremity in a 12-year-old boy. (a) Preoperative radiograph. (b) Varus deformity correction 1 year after the tension band plates insertion. (c) Varus deformity recurrence 16 months after metaphyseal screw removal. (d) Lower limb alignment correction 10 months after the metaphyseal screw re-insertion. Used with permission, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore|
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| Discussion|| |
The growth modulation procedure is a valuable tool to achieve gradual correction of lower extremity angular deformities in children. This can be permanent by doing open or percutaneous partial hemiepiphysiodesis near skeletal maturity, which is irreversible.,, Alternatively, a temporary effect that is reversible can be achieved using staples or TBPs.,, It is crucial to watch the patient closely with radiographic evaluation and remove the hardware once the correction is achieved in order to avoid excessive overcorrection. On a case-by-case basis, the surgeon may elect to allow some degree of overcorrection in anticipation of rebound.
Blount and Clarke observed that the physis becomes thin at the staple site, and once the staple is removed, growth becomes accelerated by the staple removal procedure. This physeal hyperactivity after staple removal may explain the rebound phenomenon. The rebound phenomenon may occur during the first few months after staple removal, especially in younger patients., In addition, Blount and Clarke observed that the physis closes earlier on the staple side. Zuege et al. have proposed a “safe rule” to achieve 5° of overcorrection, which will then be corrected (undone) by the rebound phenomenon. In children close to skeletal maturity, the GG hardware should be removed once the correction is achieved to avoid over correction.
Patients with certain dysplasias, such as fibular hemimelia, Morquio syndrome (type IV mucopolysaccharidosis) or multiple epiphyseal dysplasia, commonly develop a recurrence of the angular deformities after GG implants are removed., These cases required another surgery to correct the recurrent deformity. If the deformity relapses after a TBP and screws have been removed, re-insertion of the TBP and screws are required to prevent progression of the angulation., While not a huge operation to remove and replace such TBP constructs, it is certainly less invasive to simply percutaneously remove one screw and replace as needed. Recovery and return to function are nearly immediate.
Partial TBP removal surgery has been utilized by some orthopedic surgeons who specialize in deformity correction in children. The senior author has performed the described metaphyseal screw removal in eight patients since 2012. He modified the technique to include bone wax injection to prevent bone ingrowth into the screw hole. The metaphyseal screw is removed to de-activate the plate and prevent further growth modulation effect, and the epiphyseal screw is kept to prevent migration of the TBP proximally from the physis. The plate hence is “sleeping” at the physis level but can be “woken” and re-activated simply by inserting the metaphyseal screw.
This technique is minimally invasive and easy to perform under fluoroscopic guidance. At the time of screw removal, we recommend releasing the scar tissue surrounding the plate. This scar is commonly thick and could act as a tether on the plate, which in theory could lead to continuous tension forces over the growth plate, despite the absence of the screw. This could lead to continued correction and may explain why some children's limbs with broken metaphyseal screws continue to correct, despite the broken screw. Care must be taken not to injure the perichondrial ring of LaCroix. We are aware of a case at another hospital where a surgeon removed the metaphyseal screw and found that the correction continued. When the plate was later removed, the surgeon noticed bone had grown into the empty hole of the plate. Based on this discussion, the senior author added a further safety measure by injecting bone wax into the plate hole under fluoroscopy to prevent bone ingrowth into the hole of the plate.
The purpose of this study was to present the concept of sleeper plate as an option for GG treatment of angular deformity in children. The number of patients was small and did not allow us to perform a full cohort study. Future larger studies, possibly multi-center studies, are needed to examine the efficacy and efficiency of the sleeper plate technique compared with the removal of the entire TBP construct. In addition, we could not examine the rate of TBP re-insertion after partial TBP removal (sleeper plate). There are no specific indications to remove the metaphyseal screw instead of TBP removal as there are no data available to allow prediction of deformity rebound after TBP removal. It is up to the clinician to determine who may be at greater risk for rebound and for those patients to consider the sleeper plate technique. While most pediatric orthopedic surgeons may elect total removal of the TBP construct, some may consider the possibility of rebound and therefore will find the sleeper plate technique useful. The described technique is not difficult, though some fluoroscopy is required to both remove the metaphyseal screw and also to find the TBP screw hole for metaphyseal screw re-insertion. If the sleeper plate technique is done in young patients, the surgeon may need to consider the size of the retained plate, because a longer plate could possibly be required by the time the metaphyseal screw re-insertion would be needed.
A recent study demonstrated that rebound deformity occurred in only 18% after TBP removal compared with 22% after metaphyseal screw removal. The authors also described a tethering pattern of the TBP construct after removal of the metaphyseal screw. We have heard of such cases, and therefore we added bone wax injection into the empty screw hole after metaphyseal screw removal to prevent bone ingrowth into the empty hole. As shown in our case series, the sleeper plate technique was primarily done for patients with congenital femoral deficiency and adolescent Blount's disease. Once deformity correction is achieved and when hardware removal is indicated, we discuss with the parents the possibility of having to re-insert the TBP if deformity rebound happens. We counsel the parents to consider the sleeper plate option (removing only the metaphyseal screw) if patients are not close to skeletal maturity. We acknowledge that after the metaphyseal screw removal, not all patients develop rebound of the angular deformity and that an additional procedure may be needed to remove the entire construct.
We think that TBP metaphyseal screw removal and re-insertion are minimally invasive procedures that simplify the treatment of deformity rebound or recurrence. Metaphyseal screw removal and re-insertion are easy outpatient procedures with minimal soft tissue dissection and easy postoperative recovery.
Declaration of Institutional Review Board Exemption
The institutional review board of the senior author (JEH) determined this retrospective study to be exempt.
Financial support and sponsorship
Conflicts of interest
Dr. Kadhim and Dr. Hammouda have no conflict of interest. Dr. Herzenberg is a consultant for Smith & Nephew, Orthofix, NuVasive Specialized Orthopedics, WishBone Medical, Bonus BioGroup, and OrthoPediatrics. The following organizations supported the institution of Dr. Herzenberg: Arthrex, Avitus Orthopaedics, CyMedica Orthopedics, DePuy Synthes, Johnson Controls, Metro Prosthetics, MHE Coalition, NuVasive Specialized Orthopedics, Orthofix, OrthoPediatrics, Paragon 28, Smith & Nephew, Stryker, Supreme Orthopedic Systems, Vilex, and Zimmer Biomet.
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