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Slipped capital femoral epiphysis: Controversies and current treatment options

Issue: October 2012

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Slipped capital femoral epiphysis is the most common hip abnormality in the adolescent patient. The most commonly quoted classification was supplied by one of our panelists and is based on the patient’s ability to bear weight, even with aids. The current surgical management of stable slips is percutaneous fixation with a single, cannulated screw crossing the physis. However, the management concepts for the treatment of unstable slips has been subjected to criticism.

This Orthopedics Today Round Table discusses slipped capital femoral epiphyses from diagnosis to surgery and the current standard of care. We also discuss the preoperative, perioperative and postoperative protocols and parental counseling.

Jose Herrera-Soto, MD

Moderator

J. Eric Gordon, MD: When a stable slip is identified at our institution, we always admit the patient whether the slip is identified in the emergency room (ER) or in the office. It seems that at least once a year we will have a patient who presents to the ER with a stable slip diagnosed by an orthopedic surgeon or pediatrician and has been scheduled for surgery within a few days who has either tripped or fallen and converted a stable slip to an unstable slip. In my mind, this is real disaster and we do everything we can to avoid this situation in our patients. The patient is kept nonweight-bearing once admitted.

If the patient has a stable slip, then he or she is admitted immediately. Then there is a decision made about the surgical timing of whether to treat the slip with in situ screw fixation that day or the next day semi-electively. As long as the slip is stable, the decision is based on the patients NPO status and the availability of the surgeon and operating room. If the patient is admitted and scheduled for pinning the next day, then I allow patients, if they are mildly uncomfortable and the pain level has not changed in the last few weeks, to weight bear back and forth to the bathroom with assistance. I do not have these patients use crutches. The patients who I have seen with a stable slip that has become unstable following diagnosis almost always trip over crutches causing them to fall and displace the slip. I think children who are not terribly coordinated may be more at risk trying to learn to maneuver with crutches than allowing them to weight-bear as tolerated for short distances with supervision.

Wudbhav N. Sankar, MD: I admit patients that night and schedule surgery for the next day. I keep the patients on bedrest until the surgery can be completed. While I realize that many stable slips have been present for months, I think the risks of conversion to an unstable slip, while small, are important. I am aware of several cases that converted to an unstable situation while waiting for elective surgery.

Randall T. Loder, MD: I admit patients that night, keep them on strict bedrest and then do surgery the next day. If they refuse admission, then I document the refusal in their chart. I have seen stable SCFEs become unstable just by walking in the hall.

Herrera-Soto: I admit patients the same day and even place them on bathroom privileges. Unfortunately, I have seen several cases of patients are sent home and return after a fall with an unstable slip.

Gordon: My preferred method to treat an unstable slip is to perform an emergent, closed, gentle reduction in the operating room and then to stabilize the hip percutaneously with two, large fully threaded screws. I place these screws so they are both relatively central, although neither is completely central. After the hip has been stabilized, I perform a percutaneous arthrotomy. These results have been published in the Journal of Pediatric Orthopaedics and, at least in our experience, this treatment approach seems to have about a 10% to 15% rate of avascular necrosis (AVN). However, the rate increases somewhat if the patient is treated more than 24 hours after the traumatic event. Unstable slips at our institution that are identified within 24 hours of the unstable event are surgical emergencies and are treated as soon as we can get the patient to the operating room.

The key portion of this procedure is that the slip is reduced in a gentle fashion. I always perform this reduction with both the hip and knee in extension. The knee in flexion provides too large a lever arm and the reduction maneuver tends to be too forceful. When reducing the hip, it needs to be reduced back to the pre-unstable position, which is usually not a completely anatomic reduction. This point can usually be identified if the image is carefully examined looking for evidence of callus formation. I usually term this either a positional or a gentle reduction. I dislike the term “inadvertent reduction,” which has been used in some settings to minimize the surgeon’s responsibility for reducing a hip, and has had a bad connotation. I think somehow this gives people the idea that we have placed the patient on the table and were extremely surprised when the hip reduces. In reality, the surgeon realized all along that he or she was doing this by positioning the patient. Again, this reduction has to be gentle.

The fixation has to be stable. The placement of a single screw allows motion at the physis, and I think adding an additional screw allows for stability and improves the later outcome as well as decreasing late progression of the slip.

I think the capsulotomy has to be performed in order to decompress the hip to allow venus outflow from the head. Although I think some of these slips will do well without a capsulotomy, there is a substantial percentage that have a high pressure after reduction. This is one of the theoretical causes of a vascular necrosis. Hips that present more than 3 days or 4 days after the unstable event have a much poorer prognosis. In these situations, I have recommended patients consider surgical hip dislocation to fully evaluate the blood supply and do everything we can to maintain it. I personally do not do this, but would enlist the aid of one of my partners to treat these patients on a little more elective basis within the next 24 hours to 48 hours.

Sankar: If the plan is for in situ fixation with capsular decompression, then I try to do the cases as soon as possible, in the middle of the night if need be. However, I generally prefer doing the modified Dunn procedure (open reduction via surgical dislocation) for these slips and I find it safer and easier to perform these surgeries during daylight hours with the appropriate staff available. This may mean having to wait until the next morning, but no longer than that as I will cancel my other obligations so the case can be done as soon as possible.

Loder: I treat within 24 hours with simple, repositioning, two-screw fixation and decompressive capsulotomy.

Herrera-Soto: Based on my experience and results, I prefer to do a gentle manipulation, capsulotomy and fix with two screws.

Gordon: I use a fracture table for all of my SCFEs, even for bilateral slips. If I am planning on pinning both hips, then I will perform a pinning on one side with the fracture table and then reposition the patient and re-prep and drape to perform the second side. I believe this method gives me the best view of the hip and is the best way for me to get orthogonal views while I am placing pins.

Sankar: I use a flat top Jackson table for stable slips. For unstable slips, I do the modified Dunn procedure in the lateral position on a Jackson table. If I were going to treat an unstable SCFE with percutaneous fixation, then I would choose a fracture table.

Loder: I use a fracture table. I have no real tricks. Do not prep/drape before you make sure you can get good flouro pictures.

Herrera-Soto: I prefer the flat top table to the fracture table. It gives me plenty of flexibility and allows bilateral cases to be done easier. I like to flex the hip once the guidewire is in and have the C-arm come from “under the top” to do a lateral. You can also abduct the thigh and externally rotate the hip and do the same maneuver with the C-arm. This will give a good lateral without the risk of bending or breaking the wire.

Herrera-Soto: When do you allow a patient with a stable slip to walk? When do you allow a patient with an unstable slip to bear weight? When will you allow patients to play sports?

Gordon: For a stable slip, I allow patients to be weight-bearing as tolerated immediately after surgery. We usually give them crutches, and my normal first follow-up is at about 2 weeks. Probably three-quarters of the patients at that time are fully weight-bearing and ambulating without crutches. In the distant past, I had patients use the crutches for at least 2 weeks. I have not seen an increased rate of slip progression or other problems since changing my protocol and allowing patients to weight-bear as tolerated right away.

Unstable slips are kept non-weightbearing for at least 6 weeks. Following an unstable slip, my protocol is to treat the patients with emergent reduction, stable screw fixation and arthrotomy and then mobilize them to non-weight-bearing afterwards on crutches. I usually see those patients 2 weeks postoperatively to check radiographs to make sure the position has not changed. At 6 weeks postoperatively, I will see patients back with both a plane radiograph as well as a bone scan with pinhole views of the hip to evaluate for AVN. If the patient has no evidence of AVN on the bone scan, then I will progress them to weight-bearing as tolerated and start physical therapy for some abductor strengthening and to progress them off of crutches. However, if the bone scan shows evidence of AVN, then I will progress much more slowly. I usually allow them to be partial weight-bearing on the hip at 6 weeks and discontinue the crutches 10 weeks to 12 weeks postoperatively. Following that, I will follow the radiographs along for the next year or so on an every 6-week to 8-week basis gradually progressing their activity.

For stable slips, I will allow to resume sports usually at 3 months to 4 months after the in situ screw fixation. For unstable slips, I will hold off sports for at least 6 months postoperatively if there is evidence on the bone scan of AVN. If there is evidence on the bone scan of AVN but no radiographic evidence by 6 months to 8 months postoperatively, then I will allow them to gradually resume some light sporting activities.

Sankar: I allow patients with stable slips to partially bear weight with crutches (four-point gait for bilateral slips or toe-touch weight-bear [TTWB] for unilateral slips) for 6 weeks before progressing their weight-bearing. Unstable slips I generally keep TTWB for 8 weeks, which is when I can usually see radiographic signs of healing. Expected healing is 6 months for both assuming there are no complications.

Loder: If the hip is stable, then the patient can walk at 6 weeks. If the hip is unstable, then I keep the patient in a wheelchair for 6 weeks, then crutches partial weight-bearing for an additional 6 weeks. If the X-rays look good, then the patient can progress to normal weightbearing. I do not recommend sports until physeal closure, but most patients go ahead anyway.

Herrera-Soto: Patients with stable slips can walk partially the next day and progress as tolerated in a couple of weeks. Patients with unstable hips can only do toe-touch for 6 weeks and then progress their ambulatory status. Sport participation is allowed around 6 months after surgery.

Herrera-Soto: What are your indications for prophylactic fixation?

Gordon: On occasion, I will perform prophylactic fixation of a contralateral slip. I strongly encourage prophylactic pinning in patients who have unilateral slip with metabolic bone disease, such as known untreated hypothyroidism or those undergoing growth hormone therapy. I also encourage it strongly for patients who have had an unstable slip on one side, but have had little in the way of prodromal symptoms associated with it. Finally, for younger patients, I will explain the options to the family and talk about prophylactic fixation situations when the girls are 9 years old or younger and the boys are 11 years old or younger. I think these patients have a substantially higher risk of having a second slip and families often elect to proceed with prophylactic fixation at the time of fixation of the initial slip.

Sankar: I have a long discussion with the family regarding the pros and cons of observation vs. prophylactic pinning and engage the family in the decision-making process. In general, I lean toward prophylactic pinning if the triradiate cartilage remains open.

Loder: All endocrine SCFEs and the immature child (e.g., younger than 8 years old) are my indications.

Herrera-Soto: I always used an open triradiate cartilage as a guide. Now I also use the modified Oxford table to determine. Anything more than a 50% chance will get it.

Gordon: My fixation protocol for unstable slips that present within 24 hours of the acute event involves emergent surgery with gentle reduction in extension of the slip to the pre-unstable point, percutaneous fixation of the SCFE using two 6.5-mm or 7-mm screws that are fully threaded and a percutaneous capsulotomy performed with a drill bit. During follow-up, I keep the patients non-weight-bearing and I see them again 2 weeks postoperatively for a radiograph. I see them back at 6 weeks postoperatively with a bone scan with pinhole views of the hip to assess for evidence of AVN.

Sankar: I prefer the modified Dunn procedure for unstable slips. This is performed in the lateral position through the surgical dislocation approach. I pin the head with threaded K-wires temporarily so I can dislocate the head. After developing the retinacular flap, I remove the pins and reduce the head. Then I pin the head provisionally through the fovea. I reduce the head into the joint and check fluoroscopic views. If the reduction is adequate, then I place either two 4.5-mm solid screws or two 6.5-mm cannulated screws before removing the threaded K-wire. As part of the surgical dislocation, the trochanteric osteotomy is fixed with three 4.5-mm cannulated screws.

Loder: I do agentle repositioning on the fracture table and take flouro shots. If the position is acceptable to allow two screws to be placed, I perform no more maneuvers. I then performed fixation with two screws, and decompress the joint with a capsulotomy .

Herrera-Soto: I place the patient in the radiolucent table and usually hold the leg myself while the nurse preps. I still use the intracompartmental needled to monitor the pressure. I make my gentle reduction maneuver and insert the guide based on my alignment and check the lateral as described previously in this discussion. I then place the other guide prior to drilling and placing the first screw to avoid rotation of the unstable epiphysis. I use fully threaded screws for added stability and do my capsulotomy percutaneously with a periosteal elevator. The needle helps me judge if I performed a good decompression. An alternative is to inject dye into the joint and verify the extravasation of the contrast on the fluoroscopic view.

Gordon: I do not typically remove screws after fixation of SCFE. I remove them in situations where they are symptomatic or causing an impingement for the patient after the physis is completely closed. I will also remove the hardware if a situation arises or a patient develops severe AVN and has collapse with penetration of the screw through the femoral head.

Sankar: I do not routinely remove SCFE screws unless the patient is having symptoms and needs advanced imaging like an MRI. I remove the trochanteric screws placed in the modified Dunn procedure as these can cause iliotibial band tendonitis.

Loder: I remove the screws if there is AVN or chondrolysis. If the physis is still open, then you need to reposition the screws.

Herrera-Soto: I remove all of my prophylactic fixations once the growth plate has closed. I remove the prominent and symptomatic screws on the affected side.

Gordon: I routinely follow patients with SCFE who have stable slips for at least 2 years and patients with unstable SCFE for 5 years if possible.

Sankar: I follow the patients as long as possible to learn about their long-term outcomes and follow for the development of secondary problems, such as femoroacetabular impingement (FAI).

Loder: I stop following when both proximal femoral physes are shut and if asymptomatic.

Herrera-Soto: I tell all my patients and parents that I follow them for along as they want to see me. I explain to them the chance of FAI, especially for severe deformities, so they are aware that another procedure may be needed.

Gordon: For patients with SCFE, I usually counsel the family at the time of screw fixation regarding the risks of impingement. I recommend in situ screw fixation, and if the patients have discomfort, then I would recommend treatment of the impingement.

Sankar: I discuss the normal risks and benefits of surgery and spend a lot of time discussing that in situ fixation (for stable SCFEs) does not restore normal anatomy and that depending on the slip severity, the patient may be at higher risk for developing FAI due to the now distorted proximal femoral anatomy. I also discuss the pros and cons of prophylactic pinning of the contralateral side. In the case of unstable SCFEs, I spend a lot of time discussing the issue of AVN, including showing the families a representative X-ray of AVN. I then discuss the options of pinning vs. modified Dunn.

Loder: I always talk about the bilaterality issue.

Herrea-Soto: I explain what has happened and the risks of osteonecrosis if we forcefully reduce the slip. I also explain that residual deformity may lead to FAI, especially on severe deformities. They understand that another procedure to realign the joint may be needed.

Gordon: I do not order ancillary radiographic studies in the postoperative period with the exception of a bone scan with pinhole views of the hip in patients with unstable slips at the 6-week follow-up. Patients who have impingement symptoms and findings of impingement, I will routinely obtain a Dunn view in the follow-up.

Sankar: If the patient starts to complain of FAI symptoms, then I may get false profile views or Dunn lateral views in addition to the AP and frog views.

Loder: I might do a CT scan if am concerned about the screw tip position.

Herrera-Soto: I do a CT scan to evaluate screw proximity to the joint in cases of severe obesity and difficulty getting a good approach-withdrawal technique. I also do single-photon emission tomography for all the unstable slips at 3 months postoperatively to verify circulation or the need for a core decompression.

Gordon: I do not attempt reduction in a severely displaced stable slip. Although the modified Dunn procedure has been proven efficacious in significant slips, the rate of AVN is between 10% and 20%. I typically recommend a bumpectomy with intertrochanteric osteotomy for later reconstruction in patients with significant impingement. Patients with severe SCFE may benefit from a modified Dunn procedure, but I believe these are best performed in a more elective setting.

Sankar: I will attempt reduction in select circumstances if the family is well-educated and has researched capital realignment through the modified Dunn. The slip angle would need to be severe, and the family would need to be well aware of the potential risks. Since the risks of AVN are essentially zero from in situ fixation of a stable slip and we know the biggest predictor of needing a total hip arthroplasty from a SCFE is the development of AVN, I think you have to be absolutely sure you are not increasing the risk of AVN as a result of your treatment.

Loder: I will never attempt reduction as there is a risk of AVN.

Herrera-Soto: For stable slips, I will never attempt reduction. There is always the time to perform a proximal femoral osteotomy to realign the joint. Any type of reduction on a stable slip will lead to osteonecrosis.

Gordon: I do reductions of unstable slips and typically do these positionally with a gentle reduction. I never flex the hip or the knee. I position the patient on the fracture table and internally rotate the hip approximately 30% with gentle traction applied through the fracture table. Typically, the hip reduces palpably or is already reduced even with positioning on the fracture table and external rotation.

Sankar: I always do a reduction through the modified Dunn approach. The reason is that in certain circumstances the risks of AVN can be lessened through this procedure. Even if the risks of AVN are no different than in situ fixation, then at least the procedure offers the chance to restore normal anatomy. I think the high baseline risk of AVN in unstable slips justifies a more aggressive approach for these types of SCFEs.

Loder: I do gentle repositioning on the fracture table, but no undue internal rotation. Usually just induction of anesthesia and putting the feet in the leg holders results in adequate reduction.

Herrera-Soto: In the unstable slips, I take into account the amount of posterior and medial callus and try to reduce to that pre-acute slip state. However, a forceful reduction will lead to osteonecrosis.

Disclosures: Gordon is a consultant for Orthopediatrics; Herrera-Soto, Loder and Sankar have no relevant financial disclosures.