“The study data is clear”

After a primary dislocation, a non-surgical procedure should be the first treatment step for the patella, emphasizes Professor Philippe Hernigou from Henri Mondor University Hospital in Paris. GenuTrain P3 is a key tool for the orthopedic surgeon. He also uses the brace after surgery, following repeated dislocations.

life: Why is patellofemoral instability an acute and recurring problem?

Prof. Hernigou: Patellar dislocation caused by patellofemoral instability mainly affects young and active people, with a peak incidence of 30 per 100,000 per year. The high rate of recurrence is quite dangerous: 49 percent of patients with more than one dislocation will suffer from another one1. This usually results in chronic pain, osteo­arthritic changes and loss of function in the patellofemoral joint. In order to understand dislocation events, more in-depth insights into anatomy and biomechanics are helpful. The patellofemoral joint consists of the patella and femoral trochlea. It is stabilized by the grooves of the trochlea, the medial patellofemoral ligament and the tendon insertions of the vastus medialis muscle. Under normal circumstances, the joint moves in its natural trochlear grooves without causing problems, and it is stable in the different movement sections – from flexion to extension.

What causes dislocations?

Prof. Hernigou: A high-riding patella, i.e. patella alta, trochlear dysplasia, pronounced lateral patellar tilt or an excessive distance between tibia and trochlear groove, resulting in impaired biomechanical function. Lateral tibia rotation as well as hyperlaxity also play a role, as does excessive strain during exercise. Valgus misalignment, as is typical for many young women, increases the risk. The instability is usually lateral. Direct impact or trauma, however, is only a very rare intermediate trigger of dislocation. An awkward movement is usually enough.

What do you recommend in terms of non-surgical or surgical management?

Prof. Hernigou: Patellofemoral instability requires multidisciplinary management. When it’s the first, uncomplicated dislocation of the patella, without osteochondral fragments, the study data is clear: the condition is treated conservatively2. Treatment with a brace is the usual process. The objective is to center the kneecap in the trochlear groove. This alleviates the symptoms and improves joint function. With Bauerfeind’s GenuTrain P3, we have a brace that exerts medial force and can be individually adjusted using a corrective strap. It’s the perfect product to prevent patellar subluxation or dislocation during recovery. Plus, patients can effectively move their knee while wearing it. A study, conducted using a dynamic MRI test setup, showed that patellar tilt significantly decreased when a brace like this was worn3. Joint proprioception also improved. In cases of recurring dislocations, surgical management is indicated. The appropriate procedure will depend on the anatomical features of the patient and the cause of the instability. I treat 25 percent of patella patients who come to see me at the hospital with non-surgical options, 75 percent with surgery.

Do you use the GenuTrain P3 after surgery as well?

Prof. Hernigou: The brace allows me to restrict patellar lateralization right after reconstructing a ruptured medial patello­femoral ligament. In this way, I am protecting the transplanted ligament, which is subject to strong tension. A similar example is the modification of the bone architecture around the tibial tuberosity. The GenuTrain P3 can reduce tension exerted on the operated structures here, too. Trochleoplasty is another application option. After this procedure, the brace helps to maintain the result of the surgery, alleviate post-operative pain and improve sensorimotor function. In all three cases, repair processes are accelerated and early functional training achieved more quickly. After surgery, the brace should be worn for three to five weeks.

Which of the GenuTrain P3’s properties are critical for patellofemoral stability?

Prof. Hernigou: A brace must be comfortable and fulfill its purpose to ensure the patient will wear it. The GenuTrain P3 meets these requirements in different ways. It is made of lightweight, breathable material that fits well and doesn’t slip. The patella is surrounded and centered by a massage pad with a special shape. This pad extends as far as the vastus medialis muscle. Muscle activation can increase pull on the patella, which additionally improves the position of the patella in the trochlear groove. A study with medical aids showed that they positively influence thigh muscle activation patterns, and patients experience significant pain reduction4. Two spots on the pad exert slight compression on the infrapatellar fat pad, which also reduces pain. A muscle relaxation pad on the thigh compensates for tendofascial imbalance. A corrective strap that can be adjusted depending on the strain counteracts lateral shift. This ensures that the GenuTrain P3 reliably guides the patella during movement.

1 Fithian D.C., Paxton E.W., Stone M.L., et al. Epidemiology and natural history of acute patellar dislocation. Am J Sports Med, 2004;32: 1114–21.
2 Cherf, J. and L. E. Paulos. Bracing for patellar instability. Clin. Sports Med. 9: 813–821, 1990.
3 Powers, C. M., F. G. Shellock and M. Pfaff. Quantification of patellar tracking using MRI. J. Magn. Reson. Imaging 8: 724–732, 1998.
4 Gilleard W., McConnell J., Parsons D. The effect of patellar taping on the onset of vastus medialis obliquus and vastus lateralis muscle activity in persons with patellofemoral pain.
Phys Ther 1998 Jan; 78(1): 25–32.

Bilder: Bauerfeind, Hôpital Henri Mondor/Hernigou