Slipped-capital femoral epiphysis(SCFE)
SCFE is a condition that affects the femoral head at the level of the growth plate where the femoral head slips off the neck. In lay terms, can be described as the ice cream falling off the ice-cream cone. This most often happens in overweight adolescents between the ages of 10-16.
Signs and symptoms of a slip are
Hip (groin) or knee pain often associated with a limp. Parents may notice that the leg is slightly rotated externally with walking.
Treatment varies depending on the type of slip and severity. The severity is usually described as mild (0-30 degrees), moderate (30-60) or severe (over 60 degrees) slip (see figure 1). In situ fixation is only recommended for mild to moderate slips. For severe slips please see Surgical hip dislocation treatment.
Pinning in situ – closing the growth plate
Pinning in situ is the classic treatment for a SCFE (especially mild to moderate), where the femoral head is kept from further slipping off the neck by 1 or 2 large screws that eventually cause the growth plate to close. The in situ screw is fixated in a center-center position, perpendicular to the physis (growth plate) in order to stabilize it without any forceful reduction. (Figure 2a and 2b)
Closing the growth plate was classically believed to be the safest way to prevent the slip from further progressing (gold standard). The problem with this treatment is that does not correct the underlying slip deformity, which can lead to femoral-acetabular impingement (FAI) causing labral tears and pre-mature wearing of the hip (Figure 3). Furthermore, closing the growth plate on only one side can lead to an eventual difference in the leg lengths.
Surgical Approach for In-Situ pinning:
- Patient is placed on a radiolucent table
- The leg is placed with the knee cap (patella) pointing towards the ceiling. There are no attempts to reduce the position of the slip with any excessive rotation.
- A guide wire is placed in the hip, in the center-center position under radiographic guidance to be perpendicular to the physis.
- A skin incision is made on the guide wire, the length is measured and a cannulated drill is used over the guide-wire.
- The screw of the correct length is then positioned.
- Final radiographs are taken intra-operatively to ensure that the screw is not protruding into the hip joint and that its position is center-center (see figure 4A and 4B)
- The skin is closed.
Pinning in situ – Leaving the growth plate open
An alternative approach to treating slips is to stabilize the physis while leaving the growth plate open. This treatment allows the deformity to remodel and prevents any limb length discrepancies from occurring.
Figure 5a-d is an example of a laterally threaded screw that is placed through the femoral neck and attaching it to the femoral head. It prevents further slippage while allowing the neck to continue to grow (i.e. leaving the growth plate open) and allows for the deformity (bump) to remodel during the growth process. However, the pin is left outside of the bone laterally (proud) in order to allow for growth which can be hindering for certain patients. Other similar screws are medially threaded screws, Hanssen pin and smooth pins. All of these types of pins and screws involve either leaving the screw proud or having to return to the OR in order to extract them and replace them with longer ones during growth.
Pinning in situ – The Free Gliding Telescopic Screw
The Free gliding telescopic screw follows the same principle of stabilizing the physis (growth plate) while allowing continued growth. The FG screw is composed of two parts, a male and a female component that are reversed to allow for telescopic growth and stability of the physis (Figure 6a -c).
This screw avoids protruding screw placement as it is placed fully within the bony structures. It stabilizes the slip and allows for bump remodeling if sufficient growth remains Figure 7a and 7b.
The technique is very similar to the in situ pinning technique, see the video below for a more detailed explanation:
Immediately after surgery, patients are allowed to mobilize with crutches and partial weight bearing on the operated leg.
Follow-up at 1 week for dressing, no shower x 1 week
The dressing is removed at 1 week and showers are permitted.
Fu at 6 weeks, 3 months, 6 months, 12 months and then yearly with radiographs
Xrays are done post-operatively in order to ensure slip stabilization and correct hardware placement.
The patient is instructed to look out for signs and symptoms of a contralateral slip and is told to seek urgent medical care in such a case.
Resources are provided to the patient for weight reduction programs as sustained obesity is a risk factor for a contralateral SCFE.
Physiotherapy after surgery
Mobilisations of the hip joint must begin immediately. Strengthening and motion exercises begin progressively.
Total weight bearing can usually begin as of 6 weeks post-op.
- Progressive decline of hip function (mobility, strength)
- Joint space narrowing
- Nerve injury (Neuropraxia)
- Infection of bone or joint
- Neurovascular injury or Compartment syndrome (very rare)
- Fat embolism syndrome or Pulmonary embolism (extremely rare)
For a complete list of the risks and complications, please see Risk and Complications Pinning in situ tab.