In this article, I'd like to talk about pseudoarthrosis after an avulsion fracture.
In clinical practice, it is not always easy to determine that a fracture is an avulsion fracture, but it can be overlooked as fasciitis or tendonitis.
In this case, the patient was treated after an avulsion fracture of the sciatic tuberosity, which resulted in a pseudoarthrosis.
Please take a close look at this case as it gives you a hint on how to avoid overlooking the possibility of pseudoarthrosis from an avulsion fracture.
What is an avulsion fracture?
An avulsion fracture of the sciatic tuberosity occurs when the hamstrings contract and mechanical loading occurs.
It is a pelvic disorder that has been reported in adolescent athletes, and about 30% are said to be epiphyseal avulsion fractures.
It is also reported that the incidence in males is twice that of females.
Due to the similarity in the mechanism of injury, it is often misdiagnosed as a hamstring injury, and as a result of conservative treatment, often develops a pseudoarthrosis, causing chronic pain and weakness in the leg muscles.
However, it becomes unclear whether surgical treatment is indicated in the treatment of avulsion fractures of the sciatic tuberosity.
Despite an accurate diagnosis, it often leads to the development of pseudoarthrosis after conservative treatment.
Although this is a relatively common occurrence, few reports discuss the treatment of pseudoarthrosis.
Cases
A 14-year-old female.
Informed consent was obtained from the patient and her parents for the release of her data in this scientific study.
She belonged to an athletic club in junior high school. While running as fast as she could in a relay race, she suddenly experienced pain in her left buttock and difficulty walking.The next day, she visited a nearby hospital where she was diagnosed with an avulsion fracture of the left sciatic tuberosity.
The orthopedic surgeon decided to observe her without any treatment.
However, 11 months after the injury, her pain had not improved and the fracture had not healed.Due to these circumstances, she was referred to the hospital with the author for treatment.
On the first visit, she was found to have localized tenderness in the left buttock just above the sciatic tuberosity.
She was unable to sit for 10 minutes due to the tenderness and pain in the same area.Her hip and knee joints showed no limitation in range of motion.
There is no difference in the circumference of her thighs and tibias between her two legs.
There were no abnormal neurological findings in either leg.
The radiographs revealed a dislocation of the bone fragment which was 12 mm at the time of injury.It had now enlarged to 23 mm and the fragment was enlarged.
Bone scintigraphy showed strong uptake, sciatic nodules, and bone fragments on both sides of the pseudoarticular site.
She was diagnosed with a pseudoarthrosis occurring after an avulsion fracture of the left sciatic nodule, and surgical treatment was performed one year after the injury.
The surgery was performed in the supine position under general anesthesia.
A 10 cm incision was made along the glenoid groove, and after lifting the gluteus maximus muscle, the pseudoarticular site was exposed.
The unstable bone fragment was connected to the sciatic bone by a capsule of fibrous tissue, from which approximately 1 ml of bloody synovial fluid was withdrawn by puncture.
After the tissue around the bone fragment was removed, it was fixed with two cancellous bone screws with a 6.5-mm diameter cannula inserted.
Next, the hamstring tendon was fixed to the sciatic tuberosity with three suture anchors of 2.3 mm in diameter.
From the first postoperative day, range of motion exercises of the hip and knee joints were allowed, and weight bearing on the left leg was prohibited for the first four weeks.
Thereafter, one-third partial weight-bearing was allowed, and every two weeks the load was increased in increments of 1/2 PWB, 2/3 PWB, and full weight-bearing.
Jogging was started 3 months after the surgery when radiographic bone fusion was observed.A hand-held dynamometer was used to measure hamstring strength before and after surgery at 90 degrees of knee flexion.
Six months after surgery, the hamstring strength at 90 degrees of knee flexion on the affected side had improved to more than 97% of that on the unaffected side, and maintained more than 85% of the strength with less frequent rehabilitation.
Nine months after surgery, she was able to run at full speed and returned to competitive levels of athletics.
At her follow-up three years after surgery, she continued to exercise in high school and was pain free.
Nakamatsu Y, Fukui T, Oe K, et al. Surgically Treated Nonunion following Ischial Tuberosity Avulsion Fracture of a 14-Year-Old Athlete. Case Rep Orthop. 2020;2020:8531648. Published 2020 Jun 12. doi:10.1155/2020/8531648
Conclusion
From this case, the pseudoarthrosis was the result of "conservative treatment" for an avulsion fracture of the sciatic tuberosity.
It seems that conservative treatment is the cause of most pseudoarthrosis in fractures of the same site, and treatment methods need to be considered.
However, even if surgical treatment is performed early, the outcome will be the same as in this case, and there seems to be no difference in the speed of the process whether it is early or late.
According to the report, the indication for surgery is determined by the size of the bone fragments, and although this case was 12mm at the initial diagnosis, there seems to be a belief that surgery should be indicated at 15mm.
Nevertheless, when I think about the girl who endured the pain for 11 months, this case made me think about what I would do if a similar case occurred.
