More than a sprain: What the astute GP needs to know about wrist injuries

Wrist sprains are rather like ankle sprains. Most recover in a few weeks with load reduction, physiotherapy and NSAIDs. However, when recovery does not occur as expected, you should be suspicious of something else going on.

First, a reminder about anatomy. The wrist joint is comprised of the radius and ulna bones extending down the forearm and two rows of carpal bones held together by ligaments.

If your patient has persistent pain down the radial side of the wrist, a scaphoid fracture needs to be excluded. Typically, this will present with pain and tenderness in the anatomical snuff box.

Plain x-rays need to include specific scaphoid views. If these are normal and the clinical suspicion is high, then the recommended management is immobilisation in a scaphoid cast and another x-ray in 10 to 14 days. If doubt remains, you should refer the patient to a specialist, and an isotope bone scan or an MRI scan may be required to clarify the diagnosis.

Once a scaphoid fracture is confirmed, the wrist should be immobilised in a scaphoid cast for six weeks to allow for fracture healing. Recent evidence suggests it is not necessary to immobilise the thumb for a scaphoid fracture. Very occasionally, there will be non-union, in which case operative intervention will be required.

Also on the radial side of the wrist, a distal radius fracture can sometimes show only subtle radiological features. These fractures may have an intra-articular component. If your patient presents with persistent tenderness over the distal radius and x-rays are normal, they may need specialist review and consideration of high-technology imaging (eg, MRI).

Tendons passing over the radial side of the wrist often cause problems. This is known as De Quervain tenosynovitis. Typically, there will be pain and swelling in the line of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons, and there may be crepitus on movement of the thumb.

The most provocative test is the Finkelstein sign, which is performed by tucking the thumb under the flexed fingers and moving the hand into ulna deviation (Figure 1). It frequently produces quite severe pain, so this test should be left until the last part of your examination.

If De Quervain tenosynovitis is picked up early on, good results are often obtained from splinting the thumb. The condition usually responds very well to ultrasound-guided cortisone injection to the APL and EPB tendon sheaths.

Moving to the mid-portion of the wrist, you may see patients who complain of pain in the line of the third ray (middle finger and third metacarpal). If this occurs after injury, there may have been sufficient force to cause scapholunate ligament rupture.

The scapholunate ligament is as important to the wrist as the anterior cruciate ligament is to the knee. If it is ruptured, then there is separation of the scaphoid and lunate, and it is virtually inevitable that the patient will develop post-traumatic arthritis. Therefore, you need to have a high index of suspicion for an injury to the scapholunate ligament.

It is important to arrange stress x-ray views of the wrist. These usually include a clenched fist and ulna and radial deviation views (Figure 2). These may show increased separation of the scaphoid and lunate compared with the gaps between other carpal bones in the wrist. If there is increased separation, referral to a specialist to arrange an MRI may be indicated.

Depending on what is found on further imaging, referral to an orthopaedic surgeon with expertise in managing these injuries may be required. If the ligament rupture is diagnosed early and treated actively, then post-traumatic arthritis can usually be prevented.

Over on the ulna side of the wrist, there are a few pathologies you should be aware of. The most common is a small avulsion fracture of the tip of the ulna styloid. While this may not look good from the patient’s point of view, it does not, of itself, require specific treatment. It merely indicates a moderately high-energy injury.

Of more importance is an injury to the triangular fibrocartilage complex (TFCC) and its attachments. This structure fills a potential space between the distal ulna and the lunate and triquetrum (Figure 3). It is similar to the meniscus in the knee and aids stability in the wrist.

There may be a central perforation in the TFCC, or one of its attachments may be damaged. Unless there is a high-grade tear, surgery is not usually required. In most cases, specific splinting plus a cortisone injection to the wrist joint followed by specific hand therapy exercises will be very helpful. You only need to involve a surgeon if this treatment has not helped after a couple of months.

Another issue that may cause problems arises when the ulna bone is longer than the radius. This is called positive ulna variance, and it can result in the ulna knocking into the proximal pole of the lunate. This process is called ulna impaction and is analogous to trying to manoeuvre a large car into a standard parking space in a concrete parking building – collisions are painful!

In advanced cases, there will be extra evidence of bony damage to the lunate. You should refer the patient to a specialist as there may be a need for surgical intervention in some cases.

So, there you have it. Not all wrist “sprains” are benign. However, if you are aware of these few conditions, you will manage wrist injuries to a much higher level.

Be aware of the advanced skillset of our hand therapy physiotherapists. These people have several years of advanced training in the management of hand and wrist injuries. Collaboration with them can bring excellent results and is very rewarding. Get to know your local hand therapist and you will be rewarded with a great partnership in the care of your patients.

Chris Milne is a sports physician in Hamilton

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