When is a wrist sprain not a wrist sprain? More often than you might think as it turns out! A nasty little injury to the scaphoid bone often masquerades as a simple sprain but can have more sinister consequences. This is a common injury in cyclists which occurs when you break your fall with an outstretched hand.
Here’s an example of how difficult a scaphoid injury can be to pick. I once got asked by the fullback on my first-grade hockey team to take a look at a wrist that had been troubling him for 2 months. He had a scaphoid fracture and simply didn’t believe me until he eventually went for an MRI. Yes, a first-grade fullback holding a hockey stick, playing at a high level and putting tremendous forces through his wrist using that stick to tackle other players. His wrist could handle hard impacts and rapidly rotate the stick the way hockey players do despite a scaphoid fracture. It just caused ongoing pain. Unfortunately, by the time he decided to ask and investigate, not only had the fracture not healed but half of the bone had died and required surgery and bone grafting. He didn’t play first grade hockey again.
Most scaphoids, which are one of 8 small “carpal” bones in the wrist, are injured by falling onto the hand. Pretty much anyone can fracture a scaphoid at any age, including sports people, kids and the elderly but they are most commonly seen in young males.
Most people don’t think too much of the injury at the time as the bone is small and doesn’t cause the crippling pain that a large bone fracture causes (such as a broken leg). “It’s nothing, just a sprain”. I’ve heard that dismissal more times than I can recount but often that’s what it feels like - a trivial thing. If this happens to you, ALWAYS get a professional to check it out, as my hockey playing mate should have done when he first injured it.
Why is the scaphoid bone “special”, or maybe “difficult” might be a better word? It comes down to the fact that it has a poor blood supply, so a fracture can cut the blood supply off to the proximal section of bone (ie the part of the bone closest to your shoulder). About 70% of fractures in the carpal bones involve the scaphoid, and a fair number of these won’t heal due to the poor blood supply. More on this later.
What’s it like if you break the scaphoid? Often there’s some mild pain, not a whole lot of swelling, it might be tender to touch in certain spots on your wrist near the base of your thumb or might hurt to load your wrist like doing a push up or lifting. Often, it’s not as remarkable in terms of pain and disability as you might expect for a broken bone. But don’t be fooled, get it checked out by someone who knows about this injury. I’ve seen doctors and physio’s alike miss it or fail to look hard enough to find the correct diagnosis. A clinical examination and history give a high degree of suspicion for scaphoid fracture, and this should always be confirmed with imaging. Plain X-rays are often the starting point but miss around 30% of scaphoid fractures. Currently MRI is regarded as the single best test although CT scan is also very accurate, and these more advanced imaging modalities should be used if the initial X-ray is negative.
If you miss the diagnosis, it’s highly unlikely the fracture will heal without treatment. It’s also possible that the proximal part of the bone dies, and progressively collapses causing permanent arthritis and pain. This requires a much more significant surgical procedure. The moral of the story is to check it out early and prevent these more serious complications.
To manage the injury, we come back to understanding the blood supply and the likelihood of healing to guide our decision making. Whether we manage the fracture conservatively (in a cast) or surgically depends on exactly where and how bad the fracture(s) is located. Around 70% of all scaphoid fractures involve the waist (middle of the bone), and if these are undisplaced with no associated ligament injury approximately 90% of them heal with a short arm cast for 6 weeks (Clementson et al 2020).
Waist fractures which are displaced or comminuted (multiple fracture lines) have very high non-union rates if managed conservatively (around 50% fail to heal with a cast). These require surgical fixation for healing, again with a cast for around 6-8 weeks post-operatively.
Fractures in the proximal scaphoid (proximal 1/5) are uncommon (around 5% of scaphoid fractures) but tend to require surgery in order to heal.
Whichever treatment approach is chosen, to assess healing we use both a clinical examination and CT scan to assess the extent of bony growth across the fracture line(s). Once adequately healed, Physiotherapy to restore motion and strength is begun and loading gradually resumed. It can take some time before unlimited loading is possible (think of the impact loads on the wrist of rugby players, or a cyclist riding 4hrs a day with hands on the handlebars bouncing over the tarmac and potholes).
How quickly you can return to sport or to jobs that require a high demand on the wrist depends on the exact injury and whether conservative or surgical management was chosen. Both can afford excellent healing but returning to sport in a cast isn’t recommended as it causes high non-union rates (Goffin et al 2019). In a recent review (Goffin et al, 2019) most athletes return to sport about 6-8 weeks after removing their cast, and somewhat sooner following surgery. The healing rate is, on average, a little faster with surgical fixation for athletes however consideration of the risks associated with any surgery should also be discussed with the surgeon. In either case thorough rehab of range of motion and strength is highly recommended with your Physiotherapist.
References:
Clementson M et al (2020): Acute scaphoid fractures: guidelines for diagnosis and treatment. EFORT Open Reviews 5:96-103.
Goffin JS et al (2019): Return to sport following scaphoid fractures: A systematic review and meta-analysis. World J Orthop 10:101-114.
Duckworth, A. D. , Jenkins, P. J. , Aitken, S. A. , Clement, N. D. , Court-Brown, C. M. & McQueen, M. M. (2012). Scaphoid fracture epidemiology. The Journal of Trauma and Acute Care Surgery, 72 (2), E41-E45.