Revision may be inevitable after THA in children for tumors, fractures and necrosis

It is rare when a child needs to undergo total hip arthroplasty, and the current indications pose unique challenges for surgeons who perform the procedure in pediatric patients compared to adults, according to sources who spoke with Orthopaedics Today Europe.

Robert J. Grimer, FRCS, of The Royal Orthopaedic Hospital, in Birmingham, United Kingdom, told Orthopaedics Today Europe he has replaced the hips of 84 children due to tumors. Because the procedure is so rarely done, techniques for the preservation of hip function in children are somewhat limited, and there are few standard methods used, he said.

“Over the years, our policy has been to put in the least-invasive hip replacement possible in terms of the initial operation. As they get bigger, they will need something else. It is inevitable. Almost always, I have had to remove quite a lot of muscle around the hip joint. This leads to problems with instability as they grow older, so they will have an increased risk of dislocation and revision compared to conventional hip replacement,” he said.

THA indicated for sarcoma

The most common tumors Grimer has seen in pediatric patients who need to undergo THA are Ewing’s sarcomas in the proximal femur and osteosarcomas.

A tumor is just one indication for total hip arthroplasty in pediatric patients, according to Ketil Holen, MD, of the University Hospital of Trondheim, in Trondheim, Norway. He told Orthopaedics Today Europe orthopaedic surgeons at his institution will also perform THA in children due to sequelae of developmental dysplastic hip, Perthes disease or slipped capital femoral epiphysis.

About 800 THAs and total knee arthroplasties (TKAs) in adults are performed annually at the hospital where Holen works, and 200 additional THAs and TKAs are performed at a nearby satellite hospital.

Traumatic and arthritic issues

“In addition, we treat children with femoral neck fracture complications and sequelae after septic arthritis of the hip. We do not perform tumor prosthetic surgery for children. This is centralized in Norway,” Holen said.

The center in Poznan, Poland, where Jacek Kruczyski, MD, works also performs THA in children due to sequelae of septic arthritis, but surgeons there also perform THA for juvenile chronic arthritis and post-traumatic hip deformity. They have been performing THA in children since 2005.

“We have also seen cases of post-steroid necrosis following treatment of leukemia and very few with femoral head necrosis as the result of slipped capital femoral epiphysis,” he told Orthopaedics Today Europe.

No best fixation technique

Although the indications for THA in children are many, Philippe Hernigou, MD, PhD, told Orthopaedics Today Europe, the fixation used for THA in these cases is also varied. There is no one perfect technique, he said, and the technique the surgeon uses may depend on his or her own comfort and skill level.

“Indications for total hip replacement in children are rare and exceptional and can include tumors, juvenile rheumatoid arthritis and osteonecrosis. Fixation techniques also depend on the age of the patient. Cementless fixation is sometimes the favorite option of the surgeon, but in some situations cement is necessary,” Hernigou said.

Holen said his standard fixation technique for THA in a pediatric patient usually involves a cementless stem and acetabular component.

Implant selection can be difficult

According to Holen, selecting the best implant for a pediatric patient can be challenging because many times these patients who need THA have already undergone multiple surgeries during their lifetime, and that can lead to proximal femoral deformities.

“At our clinic, we often use the Unique prosthesis (Scandinavian Customized Prostheses). This is a custom-made femoral stem developed by Prof. Emeritus Pål Benum at our hospital for patients with deformed anatomy in the proximal femur. Many of these patients have been through several surgical procedures during childhood, and proximal femoral deformities are common. If there is normal anatomy in the proximal femur, we now prefer to use the Hactiv femoral component (Evolutis). In the acetabulum, we use the Reflection Cup (Smith & Nephew). We are very comfortable with all these components,” Holen said.

In the acetabulum, Kruczyski said he uses press-fit fixation of the component and sometimes additional screw fixation. Because of the small stature of pediatric patients, they need implants with smaller stems and acetabular components to ensure a proper fit.

“Implant selection is [based on] the type of deformity of the hip. In most cases we use fully hydroxyapatite-coated conventional stems with the smallest sizes available, such as a Corail (DePuy Synthes) bantam, or short stems in selected cases. In cases with metaphyseal deformity, Wagner (Zimmer) round, conical stems should be considered,” Kruczyski said.

Age determines cup material used

In younger children, often all the surgeon can do is use a 28-mm femoral head, which can fit into the acetabulum of the patient’s own hip. Their hips undergo lateral subluxation over the course of several years, which is common in pediatric hip replacement, Grimer said.

Children who receive a unipolar or bipolar head during THA will often have hip subluxation at some point and a revision procedure will be required, he said.

“Depending on how old the child is, if [he or she] is very young, you will try do an osteotomy of the pelvis to contain the femoral head better. But in an older child, you will probably revise it to a conventional hip replacement. Because of the problems of instability, we now tend to use a tripolar cup, or a Serf Acetabular Cup (Omni), which we have been very pleased with in our revisions of these kids, because of the low dislocation rate,” Grimer said.

Age affects implant material used

When a child undergoes THA for a tumor, 10 cm to 25 cm of the femur must be removed, according to Grimer. Therefore, he and his colleagues typically use custom-made implants from Stanmore Implants in such cases.

For younger and smaller patients, unipolar cups are used on the acetabular side and bipolar cups are used for older children. Grimer said he uses uncemented Serf cups in teenagers.

According to Hernigou, the best bearing to use for THA in pediatric patients are ceramic-on-ceramic.

However, if a ceramic-on-ceramic bearing is unavailable because of the patient’s size, Kruczyski said a ceramic head on a polyethylene acetabular liner will work well.

Holen said orthopaedists at his institution use ceramic heads in all procedures when they can — preferably a 32-mm head, but in some cases a 28-mm head is used for a narrow acetabulum, and the acetabular component choices in these cases are made of cross-linked polyethylene.

Revisions to be expected

Because children are still growing, Grimer said most of these patients will absolutely have to undergo a THA revision in the future. In a 2011 study he and colleagues conducted, 40 pediatric patients with proximal femoral tumors underwent THA. Thirteen patients underwent a revision THA and three patients had an amputation. One child later required an amputation after multiple failed revisions.

According to results of the study, the overall survival of all THAs with failure defined as revision for any reason, was 74% at 5 years and 47% at 10 years postoperatively. The investigators saw better results in the 22 children who were older than 11 years of age at the time of the primary procedure.

It is important for parents and for families to understand their children are going to be mobile for several years, but revisions will happen, Grimer said.

“It is such an unusual indication. I have done 84 in less than 30 years. That is less than three a year in a very busy unit. Most of the kids do very well, though. The problems arise when you have to remove a lot of muscle around the hip and you have to remove the abductor. They will have a very weak leg, of course. The main message from all of this is that revision is inevitable. You have to sit the family down and let them know that what you are doing will keep them mobile for a few years, and then it will fail,” Grimer said.

Complications to be expected

Complications can be associated with these procedures and, according to Grimer, the most common complication is infection following pediatric THA for a tumor.

“That is a reflection of the extent of the operation and the size of the bone that you have to remove. However, it is also a reflection of the patients undergoing off and on chemotherapy and some of them having had radiotherapy. That is definitely one of the issues,” he said.

Kruczyski and Holen have not observed many complications among their young patients undergoing THA, although Kruczyski said one child had a dislocation and another child had a femoral fracture.

Hernigou said in his experience the two most common complications arising from these procedures are loosening and osteolysis, both of which can lead to revisions in the future for a young patient.

PROMs are important

Although THA can offer patients positive outcomes and can restore mobility in children, Holen said it is important for a physician to understand how patient satisfaction and patient-reported outcome measures (PROMs) apply to the overall procedure and its results.

A limping child in need of a hip replacement can be bullied and ostracized, he said, which can lead to unwanted psychological effects.

“Children with disabling hip disorders need special attention. Lack of participation in physical activities may lead to social isolation, and some are bullied because of limping. It is very important to be aware of this, and therefore, one should not wait too long for a hip replacement in children. Our youngest patient is a 13-year-old girl with a Perthes sequelae. She was on crutches and in a wheelchair before the operation just a few weeks ago. She is now very happy with a pain-free hip and she can socialize with her friends again. I think PROMs for children operated with total hip replacement are very important,” Holen said. – by Robert Linnehan

• References:
• Daurka JS, et al. J Bone Joint Surg Br. 2012;doi:10.1302/0301-620X.94B12.29124.
• Kampen MV, et al. J Bone Joint Surg Am. 2008;doi:10.2106/JBJS.F.01182.

• For more information:
• Robert J. Grimer, FRCS, can be reached at The Woodlands, Bristol Road South, Birmingham, West Midlands B31 2AP, United Kingdom; email: robert.grimer@nhs.net.
• Philippe Hernigou, MD, PhD, can be reached at 51 Avenue du Maréchal de Latte de Tassigny, 94010 Créteil, France; email: philippe.hernigou@wanadoo.fr.
• Ketil Holen, MD, PhD, can be reached at Department of Orthopaedic Surgery, Institute of Neuroscience, University Hospital of Trondheim, N-7006 Trondheim, Norway; email: ketil.holen@gmail.com.
• Jacek Kruczyski, MD, can be reached at Department of Orthopaedics, Orthopaedic Oncology and Traumatology, Poznan University of Medical Sciences, 28 Czerwca 56 St. No. 135/147, 61-545 Poznan, Poland; email: jacek@man.poznan.pl.

Disclosures: Grimer, Hernigou, Holen and Kruczyski report no relevant financial disclosures.

 

What bearings do you prefer for total hip arthroplasty performed in patients younger than 20 years old?

Metal-on-metal is out

First of all, we prefer non-cemented implants, both on the acetabular and femoral side. Usually, the material used these days is titanium, so there are very few circumstances where we might change that planning. Our standard would be non-cemented titanium implants.

If the children perform normal sport activities and do not participate in risky sports, such as parachuting or kickboxing, we would prefer ceramic-on-ceramic for articulation. If the patient, family or anyone else feels the risk is too great for the ceramic to crack, we then prefer to use a ceramic head and a highly cross-linked (vitamin E) polyethylene liner for the socket. Metal-on-metal is more or less gone.

Rüdiger Krauspe, MD, PhD, is the Director of the Orthopaedics Department at the University of Düsseldorf, in Düsseldorf, Germany.
Disclosure: Krauspe reports no relevant financial disclosures.

Bearing less important than implantation

The outcomes of total hip arthroplasty (THA) in the young patient varies, largely because of the wide spectrum of diagnoses associated with hip disease in this group of patients, such as sequelae of developmental dysplastic hip, osteonecrosis or juvenile rheumatoid arthritis. The complexity of deformities associated with the need for prolonged durability requires a dedicated approach be used.

For the young active patient who needs a THA, wear in the long run is still a major concern. Although tremendous advancements have been made in developing alternative bearing surfaces, problems persist even with the newest technology. Polyethylene has been the preferable bearing surface for the acetabulum, but is associated with more wear debris. Highly crosslinked polyethylene has decreased wear by about 94%, including a substantial decrease in pitting and delamination. It can be used in combination with a metal head or a ceramic head.

Although expensive, ceramic-on-ceramic (CoC) bearings have been a valid alternative, especially in the young patient, due to the fact they offer biocompatibility, very low friction and high wear resistance, making this a valid alternative. However, the incidence of squeaking or noise may be higher with CoC bearings, and some patients find it intolerable.

There is still a lack of evidence for what would be the best bearing surface for THA in the young patient, but I would still select metal on highly cross-linked polyethylene. But, the type of bearing surface probably is not as important as how the device is inserted and who does the surgery. Given the frequent complexity of THA in the very young patient, special attention should be given to the preoperative planning, anatomical implantation of the prosthesis and careful implant selection, in order to improve the long-term result.

Manuel Cassiano Neves, MD, MSc, is the Chairman of the Pediatric Orthopaedics Department of CUF Descobertas Hospital, in Lisboa, Portugal.
Disclosure: Neves reports no relevant financial disclosures.