Developmental dysplasia of the hip: traction

Traction: what is it and what is its purpose?

In cases of hip dislocation, traction has always served the function of helping to return the head of the femur into the acetabulum, meaning the primary goal of treatment is to reduce the hip.

It is essential, however, that this reduction is performed in a non-forced manner and following all the basic rules of treatment, so as to reduce the main risk, avascular necrosis of the hip (see fact sheet).

Reduction can be performed in most cases on an outpatient basis using the appropriate retractor (Pavlik, flexion retractors, etc.), especially in cases diagnosed early.

If this fails and in older children (over 6 months, the hip retractors lose their effectiveness), the next level of treatment is “closed reduction” (with or without adductor tenotomy): with the child asleep, the hip is reduced to the correct position using appropriate maneuvers, centering is verified with appropriate diagnostic tests (ultrasound, fluoroscopy, X-ray, arthrography), and a cast is applied to keep the hip reduced.

Traction in hip dislocation consists of preceding this closed reduction with a period (from one week to several weeks) in which the child is placed in bed with his legs tractioned by small weights , connected to the legs themselves through a system of pulleys, ropes and a plaster fixation to the skin.

The purpose of this period of traction is multiple:

• It should make the reduction more effective, i.e. make the success rate higher: in case of failure of the closed reduction, it is necessary to proceed with the “open reduction” (=surgical), i.e. surgically free/lengthen the structures that prevent the reduction.
• It should make the reduction less forced: by progressively lengthening the shortened structures (muscles, tendons, capsules, etc.), theoretically less force should be needed (or less tension generated) to reduce the femoral head.
  This should consequently reduce the risk of avascular necrosis.

What are the risks of traction?

Traction for hip dislocation reduction is not without risks and issues , which should be evaluated when deciding to undertake this procedure. The main critical issues are:

• Vascular-nervous risks, compartmental system
• Skin bedsores: relatively common: experience is required to manage a child in traction
• Patient commitment (position intolerance, feeding difficulties, etc.)
• Employment for families (prolonged hospitalization, absence from work, etc.)

Features of traction for hip dislocation:

There is not just one type of traction but based on habits and schools there may be differences in:

Direction of traction:

• Longitudinal (Petit-Sommerville-Morel, etc.)
• At the zenith (overhead, Bryant): that is, upwards

Duration:

• 1 week to several weeks.

How is traction performed?

Typically, initially only the plaster bandage is applied to the limbs, allowing the bandage time to adhere and the circulation to adapt (risk of swelling of the extremities).
Over the next few days, the weight system is connected and the weight of the traction is gradually increased; a countertraction system is placed to prevent the weights from causing the child to slide toward the foot of the bed. Generally, the unaffected leg is also included in the traction to prevent traction on just one limb from causing the pelvis to rotate (though less weight is usually applied to the unaffected leg or the weight increase is stopped earlier).
Depending on habits, you continue to increase your weight up to 30% or 50% of your baby’s weight.
Periodic clinical or radiographic evaluations are scheduled to verify whether the traction is causing the femoral head to “descend” or is “softening” the structures, allowing for better centering.
Once the orthopedic surgeon considers the desired effect to have been achieved, he schedules the closed reduction in the operating room.
In some cases, having already verified the poor effect of traction, an attempt at closed reduction is planned, but with preparation for a possible open reduction.

How has traction changed over the years?

As the years have passed and society has changed (family needs, the need to reduce costs, etc.), the characteristics have also changed.

The first descriptions were based on a traction prolonged over time (weeks and weeks), in which in successive phases we meticulously and progressively tried to bring the head of the femur into the acetabulum already on the table: first the traction was longitudinal, then in progressive abduction, then in internal rotation and finally the weights were reduced to make the head enter the acetabulum.

More recently in most cases it is programmed

• Traction only for “softening” : the duration is reduced to a few days/a week; the duration is in fact already established at the start; it is performed only in the longitudinal direction and not on the other planes
• “Part-time” traction : babies are separated for a few hours to allow for breastfeeding
• Home traction : to limit hospital stays, instructions are provided for performing traction at home (in these cases it is difficult to verify that the traction is performed as prescribed)

This has certainly led to a notable reduction in the commitment for families and a reduction in hospitalisation costs but in some ways it has partially distorted the initial principles of the traction itself, weakening its theoretical effectiveness.

Is traction used by everyone?

Traction is currently not used equally across the world but is influenced by local customs. It is widely used in Europe (in a 2018 survey, 65% of EPOS members stated they use it when necessary) and Asia, but less so in the Americas (only 24% of POSNA members use it). However, the trend is declining compared to the past (Alves et al., JCO, 2018).

Is traction really effective for hip dislocation?

Several scientific studies have aimed to understand whether the use of traction could facilitate the reduction or protection of the hip from the risk of avascular necrosis.

The landmark work that questioned the usefulness of this procedure was Weinstein’s 1997 paper.

In his work, Weinstein approaches the effectiveness of traction in a methodical and extremely scientific way, providing strong arguments and also analyzing the limitations of previous scientific works.

Summarizing here the arguments of that work and the results of subsequent literature, we can underline that:

• Traction has not been proven to reduce the force required for reduction. It is difficult to quantify the force or tension in these cases. The relaxation that occurs during bloodless reduction is likely related to anesthesia rather than traction. Essentially, after traction in the operating room, the hip often feels “softer,” allowing for reduction. However, this sensation is similar in children who do not undergo traction, simply because they are fully relaxed due to the anesthesia.
  It is not uncommon in children who were indicated for traction and subsequently achieved a non-forced reduction at other centers, without the need for traction.

From an anatomical-pathological point of view we can say that:

• Intra-articular obstacles (transverse ligament, teres ligament, capsule, inverted labrum) are the main obstacles to reduction and are not affected by traction
• Extra-articular obstacles (adductors, iliopsoas): either are not stretched (for example, the iliopsoas in zenith traction, since the hip is flexed) or would require a lot of time and a specific position (for example, abduction to the bed). Furthermore, the surgical procedure of lengthening the adductors is simple and low-impact.

Traction has not been proven to reduce the rate of open reductions. The literature on this issue is conflicting.

Furthermore, it doesn’t necessarily mean that a non-operative reduction is superior to a surgical one , or that one should avoid surgery at all costs. Although the primary goal for inexperienced parents is often to “avoid surgery,” there are many factors to consider when judging a treatment, which are often more important than simply the difference between non-operative and surgical. For example, the quality of the reduction, the safety margin, the degree of subsidence, etc.

Traction in hip dislocation has not been proven to reduce the risk of avascular necrosis. The literature on this issue is also conflicting.

All things considered, there are many factors that can cause necrosis, it is difficult to understand what the role of traction really is .

Conclusions: When to use traction?

In the absence of demonstrated effectiveness of traction, we believe it is appropriate to:

• Avoid using traction at all “for school”: many of these children do not really need it
• Its use should be reserved for selected cases based on specific clinical (even very severe) or radiographic characteristics. For example, it is advisable to use standardized, international classifications, such as the International Hip Dysplasia Institute’s radiographic classification or the Graf classification (for example, if a selection is necessary, even Graf type 2c/D cases should not require traction).
  It goes without saying that, while the role of traction is controversial, there are treatment principles that have certainly proven effective in ensuring success and reducing the risk of necrosis, so we consider it counterintuitive to apply traction (with all the effort that this entails) if the other basic principles are not respected (for example, if a cast is then applied in a forced position, see the fact sheet on necrosis).

OrthoChildren center has an outpatient clinic that handles all aspects, from ultrasound diagnosis to the application of retractors or casts, to surgical procedures 

Please refer to other sheets for specific aspects

Bibliography:

• Li YQ, Li M, Guo YM, et al. Traction does not decrease failure of reduction and femoral head avascular necrosis in patients aged 6-24 months with developmental dysplasia of the hip treated by closed reduction: a review of 385 patients and meta-analysis. J Pediatr Orthop B . 2019;28(5):436-441. doi:10.1097/BPB.0000000000000586
• Park KB, Vaidya VN, Shin H, Kwak YH. Prereduction traction for the prevention of avascular necrosis before closed reduction for developmental dysplasia of the hip: a meta-analysis. Ther Clin Risk Manag . 2018;14:1253-1260. Published 2018 Jul 24. doi:10.2147/TCRM.S166531
• Waśko MK, Pietrzak S, Szarejko A, Przybysz W, Parol T, Czubak J. Radiological Outcomes of Overhead Traction Therapy for Developmental Dysplasia of the Hip in Non-ambulatory Children. Orthop Traumatol Rehabil . 2017;19(2):127-136. doi:10.5604/15093492.1238000
• Sucato DJ, De La Rocha A, Lau K, Ramo BA. Overhead Bryant’s Traction Does Not Improve the Success of Closed Reduction or Limit AVN in Developmental Dysplasia of the Hip. J Pediatr Orthop . 2017;37(2):e108-e113. doi:10.1097/BPO.0000000000000747
• Weinstein SL. Traction in developmental dislocation of the hip. Is its use justified?. Clin Orthop Relat Res . 1997;(338):79-85. doi:10.1097/00003086-199705000-00011
• Wicart P, Seringe R, Glorion C, Brassac A, Rampal V. Closed reduction in late-detected developmental dysplasia of the hip: indications, results and complications. J Child Orthop . 2018;12(4):317-322. doi:10.1302/1863-2548.12.180088
• Kaneko H, Kitoh H, Mishima K, Matsushita M, Ishiguro N. Long-term outcome of gradual reduction using overhead traction for developmental dysplasia of the hip over 6 months of age. J Pediatr Orthop . 2013;33(6):628-634. doi:10.1097/BPO.0b013e31829b2d8b
• Terjesen T, Horn J. Have Changes in Treatment of Late-detected Developmental Dysplasia of the Hip During the Last Decades Led to Better Radiographic Outcome?. Clin Orthop Relat Res . 2016;474(5):1189-1198. doi:10.1007/s11999-015-4491-7
• Alves C, Truong WH, Thompson MV, Suryavanshi JR, Penny CL, Do HT, Dodwell ER. Diagnostic and treatment preferences for developmental dysplasia of the hip: a survey of EPOS and POSNA members. J Child Orthop. 2018 Jun 1;12(3):236-244.