SINGAPORE – Seventeen-year-old Nur Insyirah twisted her right knee playing football when she was just 12. She fell hard and her knee swelled and hurt badly.
Following the incident, Insyirah went for physiotherapy but continued to experience a “funny feeling” in the knee whenever she ran. At times, it also felt like it might give way. She was even able to use her fingers to move her kneecap from side to side.
Undaunted, the sports enthusiast continued her pursuit, even picking up hockey and floorball when she entered secondary school, going on to represent her school in floorball. Unfortunately, she had to give up playing competitively at 15 after experiencing severe pain in her right knee.
A subsequent diagnosis showed recurring kneecap dislocations, and scans later revealed that she had suffered a cartilage injury to the inside of her kneecap.
Insyirah’s case has become increasingly common, with doctors seeing more cases of kneecap dislocations among active adolescents.
The National University Hospital (NUH) sees an average of four cases every two weeks, up from an average of one such case every fortnight back in 2016. Such dislocations usually occur in adolescents, with the NUH’s paediatric orthopaedics department seeing around 100 cases a year now.
The kneecap, otherwise known as the patella, is an oval-shaped bone that sits in a groove in the front of the knee and is held in place by muscles and ligaments.
Kneecap dislocations are typically caused by a blow or sudden change in the direction of movement when the leg is planted on the ground. This might cause the thigh muscle to contract and pull out the kneecap from its groove like a train being derailed from the track.
Such dislocations can happen during dancing or sports like football, basketball, Frisbee, tennis and volleyball. A sport like running, which usually does not require rapid or lateral changes in direction, is much less likely to cause patella dislocations, but patients who habitually dislocate their kneecap might still do so, especially if running on uneven surfaces.
Professor James Hui, head of the department of orthopaedic surgery and a senior consultant at the division of paediatric orthopaedic surgery in NUH, said: “Adolescents are getting more active and participating in more sports such as soccer and basketball. This may have potentially caused the upward trend of patella dislocations.”
Globally, around 40 in 100,000 children and adolescents a year suffer from this injury, with a peak for those aged 15.
It is relatively rare for such a dislocation to be suffered for the first time in adulthood as adults tend to be comparatively less active, Prof Hui said.
“Recurrent patella dislocation can occur in non-traumatic situations because of predisposing conditions such as bony and ligamentous imbalances,” he added.
After sustaining an acute injury, patients will experience severe pain and swelling in the knees. Patients might also experience difficulty straightening and bending their knees. In some cases, they will have difficulty walking without assistance, Prof Hui said.
To treat such dislocations, surgical and non-surgical options are considered.
Non-surgical therapy can achieve satisfactory results for patients with a single episode of kneecap dislocation.
However, in a small proportion of patients who also suffer cartilage injury after dislocating their kneecap, surgery is required to repair the cartilage. In cases of repeated patella dislocations, surgical treatment may also be needed.
In the case of Insyirah, surgery was performed to reconstruct the torn medial patellofemoral ligament in her right knee, and recreate the ligament that would prevent her kneecap from dislocating.
After her surgery, she followed up with physiotherapy to help with her recovery. She used crutches for about two weeks to help her move about and she wore a leg brace for about two months to lock and control the amount of bending in her knee. The brace also ensured that she was stable when moving.
Today, more than a year after her surgery, Insyirah can easily bend and straighten her knee with no pain.
Prof Hui said it is important to seek diagnosis and treatment as repeated kneecap dislocations could cause significant cartilage injuries.
“These patients (with repeated dislocations) have a higher chance of developing early arthritis especially at the kneecap joint. This risk appears to increase with the frequency of dislocations.”
To prevent a sports injury from happening in the first place, a good warm-up and stretch regime is helpful. However, it does not necessarily prevent kneecap dislocations from happening for the first time, Prof Hui said.
For those who have previously dislocated their kneecap, physiotherapy to strengthen the vastus medialis obliquus muscle (the muscle that sits above and centre to the kneecap) and the gluteal or buttock muscle could reduce the risks of repeated dislocations.
Patients with acute patellar instability would also have their knees immobilised during the acute period. Subsequently, taping of the kneecap or wearing of a brace can be helpful when they return to sporting activities.