Many people are born with that extra little bone in the ankle called the os trigonum or os trig for short. Studies show that up to 50 per cent of all people have this anatomic anomaly.
Without an X-ray or other imaging study, they might never know about it. It doesn’t cause any problems until and unless the person is involved in activities that require full and repeated foot and ankle plantarflexion (toe pointed downward). Ballet dancers and soccer players fall into this category most often.
When the foot and ankle is plantarflexed, the os trigonum (and soft tissues attached to it) get pinched between the tibia (lower leg bone) and the calcaneus (heel bone). Ankle pain can develop that is so severe, the dancer must stop all activities and motions that aggravate the problem. Running, jumping, and rising up on toes are out of the question until the inflammation has subsided. Physical therapy may be needed to address postural and alignment issues that could be contributing.
If conservative (nonoperative) care is not successful in treating the problem, then surgery to remove the bone may be needed. In the past, surgeons used an open incision technique to cut the bone out but problems developed. Permanent nerve damage occurred in some patients and the large, visible scar was a problem for professional dancers.
As smaller surgical instruments became available and more precise surgical techniques were developed, it became possible for this procedure to be done using an arthroscope. That is the minimally invasive method your surgeon mentioned.
In 2000, a new technique called posterior endoscopy was introduced. Surgeons can choose between using the arthroscopic or endoscopic technique to excise (take out or remove) the os trigonum.
In a recent study, surgeons from Korea reported their results comparing these two surgical techniques. It is the first study published making direct comparisons. Their goal was to “clarify the efficacy and safety of each surgical procedure.” Patients between the ages of 17 and 55 who had this surgery (os trigonum excision) were followed for three years. Results were measured using a variety of outcomes including pain, motion, function, length of time in surgery, time to return to sports participation, and patient satisfaction.
Patients in both groups improved significantly and were pleased with the results. Both techniques were considered “safe and effective.” Certainly, the length of time for the surgery and recovery were much shorter when compared with the open incision technique. In fact, these minimally invasive methods reduced full return to sports (or dance) from five months down to three months. Some patients are able to participate fully in a month’s time. And the dancers in the study were able to dance up on pointe with full motion and without pain.