Hemiepiphysiodesis Technique

Key Points:

  • Hemiepiphysiodesis, also known as guided growth, is a surgical technique used to gradually correct angular limb deformity in skeletally immature patients.
  • This surgical option is an alternative to corrective osteotomies that is associated with less pain, shorter immobilization, decreased cost, and less surgical risk.
  • Temporary hemiepiphysiodesis, by plating or stapling, can be complicated by premature physeal closure, a rebound period of accelerated growth or hardware migration; complications appear to be lower using the extraperiosteal, 2-hole plate method.
  • Although controversial in the literature, 2-hole plates with parallel screw configuration appear to be more efficient in slowing growth than divergent screw configuration. Screw size and plate size have not been shown to affect rate of angular correction.

Description:

Pathological angular deformities of the lower extremities cause children and adolescents activity-related pain, altered gait mechanics, and joint instability, and these are exacerbated by periods of growth. Angular deformities can be corrected gradually with growth by performing permanent hemiepiphysiodesis with physeal ablation or temporary hemiepiphysiodesis using Blount staple(s) (Blount, 1945) or a tension band plate (Stevens, 2007) across one side of the physis. Through guided growth, the patient can often obtain the end-result of equal limb lengths, neutral mechanical axes, and horizontal knees by skeletal maturity without destruction of any part of the physis or major surgery. As opposed to ablation of the physis, temporary hemiepiphysiodesis allows the entire physis to resume growth after hardware removal. Precise timing and surgical technique is required in order to avoid undercorrection or overcorrection.

Epidemiology:

Clinical Findings:

Etiology:

Treatment:

Complications:

Pathophysiology:

Although the clinical results can be similar for guided growth using the Blount staples and the tension band plate, the pathophysiology and biomechanical effect on the physis differs. With the staples, the physis is compressed, thereby creating a rigid fulcrum for correction within the physis; the moment arm for the remainder of the physis to produce angular correction is relatively short. (Stevens, 2007) The tension band plate, with screws on either side of the physis, creates a non-rigid fulcrum outside of the physis, relatively lengthening the moment arm.

Alternative Treatments:

Corrective osteotomy remains the classic treatment for pathological angular deformities of the extremities. Osteotomies sometimes need to be repeated as the child grows if the deformity recurs, and these surgeries carry the risks of compartment syndrome, malunion, and nonunion. Osteotomies are more likely than hemiepiphysiodesis to damage neurovascular structures and muscles. Guided growth is less likely to produce acute nerve palsies, as angular correction is gradual with growth.
 
Another valuable surgical option is permanent hemiepiphysiodesis; mechanical or thermal destruction of one side of the physis enables correction of angular deformity as growth continues through the remaining healthy physis. Ablative hemiepiphysiodesis is only an option in adolescent patients due to the permanence it brings, and is generally considered in growth plates where implants are difficult, such as the first metatarsal for hallux valgus deformity.(Davids, 2007)

Contraindications:

Physiological angular deformity generally resolves with observation, and surgery should be postponed for 6-months in order to reassess the natural history of the patient’s deformity.(Stevens, 2007) A relative contraindication is a lack of enough remaining physeal growth necessary for the required deformity correction. Lack of remaining growth potential is even more important to consider if the patient has an underlying illness affecting bone health, such as rickets, osteogenesis imperfecta, neurofibromatosis, or in skeletal dysplasias.(Burghardt, 2010)

Preoperative Assessment:

The preoperative assessment should include measurement of limb lengths and clinical deformities (both angular and rotational). Physical exam should include assessment of patellar tracking, long bone torsion, ligamentous laxity, and gait pattern. For genu varum one also measures the intercondylar distance and for genu valgum one also measures the intermalleolar distance.(Stevens, 2007) Radiographic assessment of leg lengths is by a hip to ankle standing AP image with the patellae facing forward, and a lateral view of each extremity. More detail is provided in the section on radiographic assessment of knee deformity. Skeletal maturity in adolescent patients should be assessed by analysis of ossification centers; this is most often completed with hand radiograph(s) using the Greulich and Pyle atlas.(Greulich, 1959)

Intraoperative Details for Tension Band Plate Placement:

Surgical details were first described by Stevens.(Stevens, 2007) Fluoroscopy is recommended to verify the precise location of the targeted physis, and subsequent plate positioning in both the AP and lateral planes. Through a 2.5-4 cm incision, the plate is placed in a submuscular or subfascial plane; the periosteum is protected. The plate is centered on the physis by slipping the plate over a Keith needle that is first placed into the physis. Two 1.6 mm K-wires are inserted into the screw holes, the cortex is drilled (5 mm), and the self-tapping cannulated screws are inserted. In order to avoid genu recurvatum, the plate should be placed in or just posterior to the midsagittal plane. Care is taken to avoid penetrating the physis or the articular joint surface during screw placement.
 
In a modified technique, the first K-wire is inserted percutaneously, using fluoroscopic guidance, into the epiphysis 6-8 mm distal to the physis.(Masquijo, 2015) The plate is slid over this K-wire, and then a second K-wire is inserted through the plate’s proximal screw hole into the metaphysis. The skin incision is made between these 2 wires, and the remaining steps are continued as listed above. This modification has been shown to lead to significantly shorter operative time (45% decrease), significantly less radiation exposure (77 % decrease), and incision sizes on average were found to be 4 mm smaller.
 
Screws placed parallel to the physis have been shown to provide more efficient angular correction than divergent screws.(Schoenleber, 2014) This effect is more evident shortly after plate placement, which is important when considering guided growth in patients nearing skeletal maturity. Screw size and plate size have not been shown to affect rate of angular correction.

Postoperative Care:

Early ambulation and activity is recommended, with physical therapy only as deemed necessary for regaining range of motion and strength for return to normal activities. Follow-up radiographs are recommended every 3-6 months. Plate and screws or staple(s) should be removed when full correction of the deformity is obtained, and some recommend slight overcorrection to account for some expected rebound. Depending on the patient’s age, intermittent follow-up should continue for at least 1-2 years after the index procedure, and then continued at least annually to monitor for undercorrection or overcorrection.

Complications:

Complications include permanent or premature physeal arrest, rebound period of accelerated growth, iatrogenic limb length inequality, overcorrection of deformity, hardware migration, hardware fatigue failure, and physeal bar formation after stapling. The Blount staple may cause premature physeal arrest due to altered biology from physeal compression (Stevens, 2007), and is felt to have higher mechanical complication rates as compared to plates and screws. Staple migration requiring revision surgery has higher incidence in children younger than 10 years.(Stevens, 2007) The treatment of late onset tibia vara with temporary hemiepiphysiodesis has a high surgical failure rate, particularly with morbid obesity and severe deformity.(Funk, 2016) There are multiple reports of mechanical failure of both titanium and stainless steel screws of tension band plates when utilized for late onset tibia vara.(Schroerlucke, 2009; Burghardt, 2010; Mignemi, 2013) Rebound growth can often be successfully treated with repeat staple or plate hemiepiphysiodesis if skeletal maturity has not yet been reached.(Stevens, 2007) Overcorrection or undercorrection of angular deformity requires salvage by osteotomy. 

References:

  • Blount WP, Clarke GR. Control of bone growth by epiphyseal stapling: a preliminary report. J Bone Joint Surg Am. 1949;31:464–478.
  • Burghardt RD, Herzenberg JE. Temporary hemiepiphysiodesis with the eight-plate for angular deformities: mid-term results. J Orthop Sci. 2010;15:699–704.
  • Burghardt RD, Specht SC, Herzenberg JE. Mechanical failures of eight-plateguided growth system for temporary hemiepiphysiodesis. J Pediatr Orthop. 2010;30(6):594-597.
  • Davids JR, McBrayer D, Blackhurst DW. Juvenile hallux valgus deformity: surgical management by lateral hemiepiphyseodesis of the great toe metatarsal. J Pediatr Orthop. 2007;27:826-30.
  • Funk SS, Mignemi ME, Schoenecker JG, Lovejoy SA, Mencio GA, Martus JE. Hemiepiphysiodesis
  • Implants for Late Onset Tibia Vara: A Comparison of Cost, Surgical Success, and Implant Failure.
  • J Pediatr Orthop. 2016;36(1):29-35.
  • Greulich W, Pyle S. Radiographic atlas of the skeletal development of the hand and wrist, Stanford, CA: Stanford University Press; 1959.
  • Masquijo JJ, Lanfranchi L, Torres-Gomez A, Allende V. Guided Growth With the Tension Band Plate Construct: A Prospective Comparison of 2 Methods of Implant Placement. J Pediatr Orthop. 2015;35:e20-5.
  • Mignemi ME, Martus JE. Mechanical Failure of the OrthoPediatrics PediPlate in Late-Onset Tibia
  • Vara with Moderate Deformity. A Report of Three Cases. 2013;3(2):e48.
  • Schoenleber SJ, Iobst CA, Baitner A, Standard SC. The biomechanics of guided growth: does screw size, plate size, or screw configuration matter? J Pediatr Orthop B. 2014;23:122–125.
  • Schroerlucke S, Bertrand S, Clapp J, Bundy J, Gregg FO. Failure of Orthofix eight-Plate for the treatment of Blount disease. J Pediatr Orthop. 2009;29(1):57-60.
  • Stevens PM. Guided growth for angular correction: a preliminary series using a tension band plate. J Pediatr Orthop. 2007;27:253–259.

Top Contributors:

James C. Kyriakedes, M.D.
Raymond W. Liu, M.D.