Therapeutic algorithm
- Acute and unstable fractures must be treated by open reduction and internal fixation.
- Stable fractures or those with surgical contraindications may be treated conservatively.
Controversy lies in the management of non-displaced or minimally displaced fractures.
This is a subject of recurrent debate and multiple studies have reviewed surgery versus casting for acute scaphoid fractures with dissimilar results.
Two pairwise meta-analysis [3,4] concluded that there is no evidence from prospective randomized controlled trials to favor surgical or conservative treatment for acute scaphoid fractures.
On the other hand several studies suggest that surgical management with percutaneous screws demonstrate satisfactory outcomes,
with reduced immobilization period,
earlier time to union and better range of motion at the wrist with minimal complications [5]
Steinmann and Adams [5] considered that if a scaphoid fracture is identified on plain films,
it represents displacement,
and recommend surgery with percutaneous placement of a cannulated screw. They also refer that in proximal pole fracture,
percutaneous operative fixation should be undertaken to lessen the chance of non-union.
In our opinion,
an individual assessment of each case must be made,
bearing in mind the risks and benefits,
and considering that surgical management decreases the immobilization time in young patients.
Complications
- Non-union. Non-union of a scaphoid waist fracture is considered in the absence of radiographic sings of healing after 12 weeks and a clear gap on CT [6].
These features at 6 weeks may suggest delayed bone healing.
In fractures of the proximal pole,
the average healing is between 3 and 4 months.
This type of fracture has a high rate of osteonecrosis,
thus surgical management is the treatment of choice.
- Mal-union.The most charactseristic is flexion deformity of the scaphoid (humpback deformity) but ulnar translation or pronation of the distal fragment may also occur.
- Osteonecrosis. It occurs more frequently in fractures of the proximal pole,
related to the retrograde blood supply and the small size of the fragment: 100% when the fracture involves the proximal fifth and 30% when it involves the proximal third [6].
MRI is the best imaging technique for assessing osteonecrosis.
- SNAC (Scaphoid Non-union Advanced Collapse)wrist.
Non-union may evolve into carpal malalignment and progressive radiocarpal osteoarthritis.
SNAC wrist stages depending on the progression of arthritic changes (Vender)
- Stage I. Osteoarthritis between the distal scaphoid fragment and the radial scaphoid fossa
- Stage II.
Same as stage I with addition of osteoarthritis between the scaphoid and the capitate
- Stage III.
Same as stage II with progression to the lunocapitate
Imaging techniques in diagnosis
According to the American College of Radiology (ACR),
radiography is the most appropriate technique in the initial evaluation of suspected acute scaphoid fracture [7].
Initial scaphoid series include posteroanterior (PA),
lateral,
semipronated oblique,
and PA with ulnar deviation views (Fig.
5).
![](https://epos.myesr.org/posterimage/esr/ecr2019/147278/media/809918?maxheight=300&maxwidth=300)
Fig. 5: Initial scaphoid series
References: Deparment of Radiology, Hospital Universitario 12 de Octubre, Madrid
A large meta-analysis [7] revealed that 84% of initial radiographs correctly identified a scaphoid fracture or no fracture .
The following diagnostic algorithm (Fig.6),
reflects the proper procedure for that 15% of inconclusive radiographs
![](https://epos.myesr.org/posterimage/esr/ecr2019/147278/media/809243?maxheight=300&maxwidth=300)
Fig. 6: Diagnostic algorithm
References: Deparment of Radiology, Hospital Universitario 12 de Octubre, Madrid
Accordingly,
if the radiographs are negative and a fracture is clinically suspected,
MRI is the imaging modality of choice for detection of occult fractures.
Early MRI avoids unnecessary immobilization,
reducing lost productivity cost for patients who are potentially immobilized.
MRI also offers the benefit of providing alternative diagnoses ( Fig. 7 ).
The following table (Fig.
8) compares the accuracy of repeat radiographs,
computed tomography (CT) and bone scintigraphy and the aim of the ultrasound and dual energy CT in the diagnosis of occult scaphoid fractures [8,9,10].
![](https://epos.myesr.org/posterimage/esr/ecr2019/147278/media/809370?maxheight=300&maxwidth=300)
Fig. 8: The following table compares the accuracy of repeat radiographs, computed tomography (CT) and bone scintigraphy and the aim of the ultrasound and dual energy CT in the diagnosis of occult scaphoid fractures [8,9,10]
References: Deparment of Radiology, Hospital Universitario 12 de Octubre, Madrid
Imaging techniques in diagnosis and follow-up
CT
- Bone healing.
90% - 95% of scaphoid waist fractures will predictably heal in 6 to 8 weeks [6].
In a proper healing we would see obliteration of the fracture line with normal trabeculae bridging the fracture (Fig. 9).
According to the literature,
bridging trabeculae across more than 25% of the cross-section of the scaphoid on CT often progresses a total healing without the need of additional immobilization.
[1,6] (Fig. 10)
- Non-union.
CT images demonstrate sclerosis of the fracture margins,
cyst formation and bone resorption (Fig. 11) (Fig. 12).
- Mal-union. Usually a flexion deformity of scaphoid (Humpback deformity)(Fig. 13).
CT measurements defining a "humpback" deformity are an intra-scaphoid angle > 45º (normal = 24º) and scaphoid height / length > 0.64.
Importantly,
residual flexion deformity of the scaphoid does not influence the outcome [1]
- Osteonecrosis. CT features of osteonecrosis are sclerosis,
collapse and / or fragmentation of the involved fragment.
Isolated sclerosis does not exclude fragment viability.
- SNAC wrist comprises osteoarthritis of the radiocarpal joint,
which may be accompanied by osteoarthritis of the midcarpal joint (Fig. 14).
The joint preservation of the scaphoid will depend on the state of the periescafoideas articular surfaces.
Isolated involvement between the radial styloid and the distal fragment of the scaphoid (SNAC stage I) is viable but stages II and III are not viable.
- Post -percutaneous surgery features
- Optimal positioning: centered on the axial axis of the scaphoid (Fig. 15)·
- Screw protrusion ( Fig. 16 )·
- Soft tissue injury·
- Fracture reduction or not.
Persistent displacement and abscence bone or screw integration (Fig. 17)·
- Screw loosening (Fig. 18)
MRI
MRI features of osteonecrosis are decreased signal on T1-weighted images and lack of enhancement on contrast-enhanced MRI (Fig. 19) (Fig. 20).
MRI is the imaging modality of choice for assessing osteonecrosis,
but the most useful imaging protocol remains controversial.
There are few controlled studies and there is disagreement regarding the sensitivity,
specificity and accuracy of gadolinium-enhanced MRI.
Fox et al [15],
conclude that unenhanced MRI was slightly more accurate than contrast-enhanced MRI in diagnosing scaphoid proximal pole AVN.
A few studies have shown that static,
contrast enhanced MRI can predict the viability of the fragment better than a non-contrast enhanced examination [7].
A recent study [7] compared static contrast-enhanced MRI with dynamic contrast-enhanced MRI finding poor correlation of dynamic contrast -enhanced with the histopathological findings.
However,
some investigators [7] have postulated that late contrast enhancement may be a result of invasion of fibrous tissue into the areas of osteonecrosis.
In our institution the scaphoid imaging protocol includes T1 – weighted images,
T2 fat-saturated or STIR and static contrast-enhanced sequences.