The Rule of Threes: Simplifying Complex Hand Conditions in Medicine
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The key to medicine is making a diagnosis. For it's a diagnosis that not only helps us to explain to the patient the cause of their sentence, but also allows us to give a prognosis and offer treatment options. While the key to a diagnosis is the history, examination and performing investigations, unless you know what you're looking for, choosing from a selection of diagnoses can be challenging and you won't be able to come up with an appropriate treatment plan. People in the past have used surgical mnemonics to try and remember the various options for making a diagnosis.

But these can be quite complicated. I've previously taught by using the rule of threes to divide things into simple categories. This works well for hips and shoulders, but how does it work for hands? But for so many different medical conditions. Today we're going to go through this and explain it, and at the end I will show you how this will make assessing a patient with a musculoskeletal hand condition much simpler. Welcome to Olsy Bedhead.

Good day and welcome to Aussie Med Ed, the Australian medical education podcast designed with a pragmatic approach to medical conditions by interviewing specialists in the medical field. I'm Gavin Diamond, an orthopaedic surgeon based in Adelaide and I'm broadcasting from Karnaland. I'd like to remind you that this podcast is available on all podcast players and is also available as a video version on YouTube.

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Well, you may have seen my prior podcast on the rule of threes and how it can help your medicine. In that, I talked about why dividing things into threes can be so useful. And the number three seems to repeat itself throughout life, literature, and in famous speeches. I use it all the time in medicine. If you think of a three as the most common number, then using a Gaussian distribution, you have to think about the rule of threes involving the rule of twos, threes, fours, or even fives as a simple way of dividing things up.

In my podcast on shoulder conditions, I explain how this method can not only help you remember the various diagnoses, but also make it as much simpler in assessing a patient and offering treatment options. Students, however, have asked me whether this can work in the hand because there's so many different things that can occur in the hand. The answer is yes. It gives us a structured approach. Let's break it down.

If we think of hand presentations as either being traumatic or elective, with traumatic presentations being those that may present to an emergency department and elective cases being those seen in a clinic, this is a starting point. Now the third type of presentations which are not quite as common in hands are the mixed picture, those elective type conditions that really have commenced after trauma.

Now I'll start off by saying this doesn't cover every possible diagnosis. From my experience, however, it does cover 90% of the common things that I see as a hand surgeon. And I hope it can be a good starting point for you to build upon. Let's start with traumatic conditions. My mantra is that traumatic conditions typically involve fractures, dislocations and infections. But when it comes to the hand, we also need to consider tendon injuries,

those being lacerations or evolutions of the tendon, as well as nerve injuries. Therefore, if we categorize the five main traumatic hand conditions, we have fractures, dislocations, infections, tendon injuries and nerve injuries. Let's start with fractures. When thinking of fractures, we'd start with the bones involved, that being the distal radius and ulna, or the carpal bones, or the metacarpals and phalanges. If we look at the distal radius and ulna, and focus on the radius, is this the main bone involving the wrist joint?

These can be extra-articular, and the two well-known ones are Colley's fractures, where there's dorsal displacement of the wrist, or Smith's fracture, where there's boulder displacement. Well, the fractures can be intra-articular, such as Barton's fracture, which is a boulder intra-articular fracture, where the boulder fragment is displaced all the way along with the carpus, as well as a radial solo fracture. We can have grossly commuted intra-articular fractures. These fractures may or may not have a distal ulnar fracture with it,

We go on to the carpal fractures. The most common and concerning fracture is the scaphoid, which can occur after a fall on an outstretched wrist. It can also occur after using a drill when your drill bit gets caught in the masonry and the hand twists. So the scaphoid is then poor to injury and due to its poor blood supply. This can lead to non-union, secondary to avascular necrosis. And later, it can lead to arthritis if the fracture has been missed.

Other carpal bones can also be injured as well, including the trichrecium, which is a common injury often seen on the lateral x-ray as the ligaments avulse the fragment of bone off the dorsal aspect of the trichrecium. This is really the type of wrist sprain with an avulsion of the dorsal ligaments.

If we move on to the metacarpal and palandral fractures, metacarpal fracture is often involved with the neck of the bone. This is one of the more common ones, it's known as a boxer's fracture, where someone punches something like a wall in the metacarpal neck, roller flex. Fractures can also occur at the base of the metacarpal, and this can be like a fracture dislocation pattern, where the bone is tried subluxating the carpal-metacarpal joint and fracture at the same time.

Fractures of the base of the thumb are also common. One that's important is known as a Bennett's fracture, which is intra-articular where the fragment stays with the ligaments and the rest of the bone sublux of the radio woods. You can also get fractures of the whole base of the thumb known as a Rolando fracture. And these can lead to instability and secondary arthritis. Phalangeal fractures involved in the distal phalanx are common and often quite simple, but the phalangeal fractures can be more complicated if they involve the joint surface, particularly around the PRP joint.

When looking at dislocations of the hand, these can occur at any of the joints levels, including carpal dislocations, where you might get a dislocation of the lunate bone or the bones around the lunate, or perilunate. These are considered surgical emergencies because the bones then push off the median nerve and can lead to compression of the nerve and also vascular compromise.

Because of the number of bones involved in the carpus, it's often difficult in interpreting x-rays, and they can be easily missed. It's important you're aware of the, of the 4Cs on lateral x-ray oboreas, that being the distal surface of the radius, the proximal surface of the lunate, the distal surface of the lunate, and the proximal capillate. And these 4Cs should all line up in the lateral x-ray. These dislocations can be associated with carpal fractures as well, such as the scaphoid fracture, when you transcaphoid perilunate dislocation.

We move on to the metacarpal phalangeal joints and interphalangeal joints. These dislocations are particularly common on the sports field and are often reduced by trainers. We need to be aware of them as well and leave the result in swollen hands. Associated with that, you can get an evulsion of the volar plate that stops the PIP joint hyperextending, and that's called a volar plate injury and often pulls off a fragment of bone with it.

Two important other ligament injuries are the gamekeeper's thumb, also known as the skier's thumb, the thumb when someone falls on the hand and the thumb is forced into radial deviation, tearing the oligolateral ligament or the metacarpoprolangeal joint, and this can lead to instability of the thumb. This injury is important because the ligament comes away from the joint and actually subluxates outside of what's known as the adductor upon neurosis and doesn't sit back next to the bone in many situations, not all, and that can lead to great instability of the thumb.

and pain and secondary arthritis. The other injury is the scapholina ligament injury, which is a similar injury to a fracture of the scaphoid and really is a minor version of carpal dislocation that we discussed earlier in the start. And really, given that the ligament itself can't be seen on x-ray, it's often missed. And people are more concerned about scaphoid fracture, but it should be similar to a scaphoid fracture in that it can result in chronic pain and development of arthritis later in life.

This is one of those conditions that's a traumatic presentation leading to an elective condition. And we'll go into that in further detail later. Infections in the hand can involve bones, joints or soft tissues. Infections in the joints are called septic arthritis. And the infections in these areas are also considered a surgical emergency. One type of infection that should not be missed is what I call a fight bite. When laceration occurs over the knuckle, someone punches someone in the face leading to a cut over the metacarpal palangeal joint.

and during this time the knuckle where she enters the joint introduces oral bacteria into her joint. Each time there's a tooth wound over a knuckle it should let her go a full wash out of the wound in surgery.

Flexor tendon sheath infections are also quite important because this is another orthopedic measure because the flexor sheath infection can lead to result in scarring which leads to stiffness and because it's a localized compartment the issue of the localized compartments in you associated with it. Therefore if not if it's not washed out early it can lead to a very poor puncture of the hand later on. This brings us into tendon injuries. Tendon injuries often result from lacerations or abortions.

Extensor tendon injuries may present a simple inability to extend the finger, with the common one being a mallet finger, which is an abulsion of the extensor tendon from the distal phalanx. The equivalent injury to the flexor tendon is known as a jersey finger and may result in loss of flexion. The former one is treated with a simple extension splint, while the latter requires surgical repair. If we get onto nerve injuries, these are critical in hand trauma, particularly when they're caused by lacerations.

Early assessment and repair of nerve injuries are crucial for recovery, and nerve injuries can be classified using the Settling Classification or the Sunderland Classification. The Settling Classification is easier, and ironically, it is divided up into three main grades, uropraxia, axontomiesis, and uropemiesis.

Compression injuries such as those caused by a leucatic dislocation or a mother bone fracture or lip push can lead to acute symptoms as well, requiring immediate intervention. Alright, we'll do the main traumatic conditions. What if we move on to elective pain conditions?

The elective issues are those that don't require an emergency trip to a hospital, but definitely require attention in a clinic. We can divide these into five key areas as well: joints, bones, tendons, nerves and ligaments. Plus, we've also got an extra category for those conditions that don't quite fit in anywhere else, like tumors and miscellaneous conditions. If we look at joint conditions, first let's talk about them. When it comes to the hands, arthritis is a real big one. There are a few main types we commonly see of arthritis. I want to divide these into three main areas.

Primary osteoarthritis, this is a wear and tear variety, often from repetitive use or degeneration over the years. The more common area obviously in the hand is the interpallanular joints where it's associated with deformities, particularly seen in middle-aged patients and where the development of the Heberden's nodes at the DIP joint and Bouchard's nodes at the PIP joint. These are just osteophytes producing the lump at those joints.

It also commonly affects the base of the thumb and the carpometacarpal joint, leading to carpometacarpal arthritis. Or the region just below that, the scaphotrapezoid or trapezoid joint, STT joint. These lead to pain and reduce grip strength and functional limitations. While primary osteoarthritis, the risk can occur is more commonly secondary and secondary to trauma, including ligament injuries, damage to the joint surface, post-inflammatory or metabolic disease.

That brings me on to secondary osteoarthritis. This type usually follows previous trauma with damage to the chondral tissue or incongruity of the joint surface and also can relate to post-inflammatory conditions such as rheumatoid arthritis or gout, etc.

Then we get our third type, and obviously this is a quite encompassing area, the inflammatory arthritic conditions. This covers conditions like rheumatoid arthritis and other inflammatory arthroplopies, and these are systemic in nature, affect multiple joints, as well as other tissues, including tendons, ladies, or formities like oral drift or swan neck deformities, etc. We've covered this a lot previously with an interview with Sam Whittle on the podcast. Now, any of these types of arthritis can lead to the production of fluids,

Injuries anywhere can lead to production of fluid including soft tissues and tendons but what's more common in joint surface and particularly in arthritis and this produces cysts that occur near the joints of the fingers or the wrist. This is what's known as a ganglion but near the DIP joints we call these lesions a mucous cyst. If we look at bone conditions, well the most common bone issues probably are tumors or bone cysts and this will be covered in a separate podcast.

Another bone issue which you may not have heard about but which is worth knowing about is Kleinbach's disease. It's Avastinocrosis of the luna which occurs spontaneously. You look at it on x-ray, initially you might not see much but then you might see some sclerosis as the bone becomes avascular and then you might see signs of part of the joint collapsing leaving a secondary to the Avastinocrosis and that can eventually lead to arthritis. It's rare but it's worth knowing about.

Moving on to tendon conditions, well, tendon problems are pretty frequent in the hand with conditions like trigger finger and the cuvee sinus fibromibus. Trigger finger happens when the tendon larges and gets caught in the tendon sheath or flexor sheath, pulls in the finger through the lock. And you might, the patient might have trouble flexing the finger down because it's catching just proximal to the A1 pulley and the flexor sheath on the palmar side. Well, once it does flex down, they might not be able to straighten out and suddenly they have to force it out straight in their ear, like in the PUSS.

To occur with tendinitis, there's a similar condition of this. It involves inflammation of tendons on the radial side of the wrist, the first extensive compartment, often with a secondary repetitive thumb movement. It's very commonly associated with a newborn child or a pet from lifting it up. People usually report pain when gripping or twisting, especially around the first dorsal compartment over the radial styloid. You can get tendinitis in other areas too, such as the intersection syndrome.

We get pain on the dorsal wrist where the EPL tendon extends the polliculus longus, crosses over the second extensor tendons, extensor carpi radialis longus and brevis, causing pain. And you also get tendonitis in the fourth extensor compartment, that involving the extensor digitorum and interstice with the sociopare and crepitus. Tendonitis can happen just about anywhere in the hand and it's often associated with swelling and crepitus when the tendon moves. We move on to nerve conditions. Well, nerve issues occur in the hand are pretty well known, with carpal tunnel syndrome being one of the most common diagnoses made.

Carpal tunnel syndrome occurs when the media nerve is compressed in the carpal tunnel leading to numbness, tingling, a weakness of the thumb, index finger, and middle finger, and then half the ring finger. It's often worse at night or with repetitive wrist movement. The patient often has to get up and shake their hand around. They often find it worse when holding a phone or riding their bicycle.

You can get similar symptoms affecting the ulnar nerve as well, with paresthesia affecting the ulnar dip, the little finger and half the ring finger. Golden nerve compression can occur at the glial canal of the wrist, just superficial to the flexor adenacula, or at the cubital tunnel behind the middle aspect of the elbow. Patients again will report tingling and numbness in the ring and little fingers, and make it tough to perform precise movements.

With carpal tunnel and cubital cell syndrome, it's always a good idea to rule out any cervical spine issues, as nerve compression further up could be a part to play. As we mentioned previously, nerve entrapment can be a complication of acute traumatic condition.

Then we get ligament injuries. Ligament injuries can occur electively, such as chronic stretching or secondary to ligamentous laxity. But a more common scenario is a chronic presentation of a prior acute injury. An important type of ligament injury is a scapulaeal ligament injury, secondary to trauma or with delayed presentation. This is what we discussed earlier, but when left untreated, these can lead to scapulaeal advanced collapse, which can cause long-term instability and lead to secondary arthritis and the rest.

Patients often report a clunky feeling when they're gripping or loading their wrist and then they get pain. Scaphoid Fracture Non-Uterine also leads to this scenario as well. This is known as Scaphoid Non-Uterine Advanced Collapse.

Another traumatic ligament type injury is an injury to the distal radial ulnar joint and the triangular fibrocartilage. The triangular fibrocartilage is a soft tissue that fixes the radius from the edge of the radius to the tip of the ulnar, what's known as the ulnar fovea. And as the hand supernates and pronates, the radius swings around the tip of the ulnar along this soft tissue envelope. In acute injuries, but on falls, when the ulnar doesn't fracture, this ligament can tear.

Often tears as they age anyway and it's part of the degeneration and that's where chronic conditions of these can occur as well. This is where patients present with ulnar-sided pain and differently with stipulation and pronation of the wrist and it may cause a clicking sensation. This is something to keep aware of as well.

Finally, we move on to those miscellaneous groups of conditions that don't fit neatly elsewhere anywhere. These include benign and malignant tumors and congenital issues and certain soft tissue problems. I intend to discuss tumors in a later podcast, but I think there are two conditions worth knowing about. The first is Jupiter's contracture. This is a genetic condition where the palmyroplasty thickens, leading to gradual bending of the fingers, particularly the ring of little fingers.

Over time, this makes it difficult to fully straighten the hand out and the fingers get stuck in the palm as it slowly gets worse. Once you've seen a Jupyter's contracture, it's pretty obvious.

Giant silver tumor of tendon sheath is another benign type of tumor, which is a nodular growth on the tendon sheath. It often looks like a ganglion, but tends to be firm and doesn't fluctuate in size like ganglions do. So there you have it, a rundown of hand conditions, which from my perspective, I would qualify this by saying this is my opinion. It's a simple way of thinking about the conditions. I'm sure there are other conditions that may have been missed. This covers 95% of the common conditions.

This breakdown can help keep things straight when it comes to diagnosis and management, making it a bit easier to narrow down the options when a patient comes in with a hand complaint. With this approach, you're better positioned to understand what's going on and more importantly, how best to treat it. I hope this simplifies things we have faced with the hand cases to assess in a clinic. The last thing I'd like to talk about is the symptom-based diagnosis in hand conditions.

The most important thing is that they present with specific symptoms which can guide the clinician towards the most likely diagnosis. By focusing on these key clinical presentations, which involve pain, deformity, neurological symptoms, instability and lack of motion, clinicians can quickly narrow down the differential diagnosis and determine the best course of action. Let's look at each of these symptoms and how they can help target specific diagnoses.

Starting with pain, it's a common symptom both in traumatic and electric presentations, and often the primary reason patients seek medical attention. The location, type and duration of pain can provide clinical clues. In traumatic injuries, pain is usually acute and directly follows an event such as a fall, blow or a cut.

Based on the diagnosis of a traumatic scenario presenting with pain, options usually are fracture, dislocation or infection. Nerve injuries and tendon lacerations are less likely, and localising the pain can direct you towards where you need to direct the investigation, of which the most important one would be an x-ray. A presenting case of a traumatic pain is less likely to be an acute nerve injury, and whilst a tendon laceration or injury can cause pain, it's more likely to present with loss of motion, and the story also will give it away.

Likewise, with electropresentational pain, arthritis and tendinitis are the most common diagnoses for the possible representation of avascular necrosis or irritability. Once again, a site of pain can help you assist where the condition is arising, and if associated with cryptitis, the site of origin will also assist. In primary osteoarthritis, patients may experience a deep aching pain, while conditions such as the quervate tendinocytobitis will cause pain when the tendon is stretched or moved.

For the latter, fixturase and accelerated arthritis and ultrasound can confirm the tendonitis. Another presenting symptom might be deformity. Visible deformities are more common in traumatic hand conditions but may also appear in advanced stages of elective conditions. With traumatic deformities, deformities such as angulation of the metacarpal, such as in a boxer's fracture, or dislocation of the metacarpal and philanderal joint, are usually easily seen. Whilst the inability to extend or flex a joint suggests tendon injury,

In elective scenario, rheumatoid arthritis can lead to the classic deformity, such as swan necking and butoneal deformities. But these may develop over time due to joint and tendon involvement, but actually due to the advances in rheumatological management, actually quite rare nowadays. For a patient presenting with deformity, H-rays are usually an initial investigation with an ultrasound being a close second. But if you're suspecting an inflammatory pathology, don't forget to order blood markers for rheumatoid arthritis.

As I've said before, patients with tubital contraction work on progressive flexion of the formative of the fingers, particularly at the ring and little finger, due to palmar fascia thickening. And the thickening of the palmar fascia is really quite obvious. Neurological syndromes, such as numbness, tingling, or weakness, are often pointed towards compression or injury. These syndromes can be seen in both acute traumatic conditions as well as chronic oppressive syndrome. The trick here is to diagnose the correct nerve affected, exclude other causes such as cervical radiculitis,

The appropriate investigation here would be nerve conduction studies, and I've recently done a podcast with Jessica Hafner on peripheral neuropathy. Insability or joint or ligament instability can be a sign of both traumatic and elusive conditions, often leading to recovery injuries or long-term dysfunction. This is where x-rays will help diagnose chronic pathology consistent with electropresentation of instability with developing secondary arthritis, whilst ultrasound or MRI scan may help with ligament injuries.

Sometimes, however, all these investigations are not that helpful because it may be dynamic and certainly a good examination is one of the best ways of assessing it. And this is particularly important when looking at distal radial ulnar joint instability of the distal ulnar. Patients finally may present with lack of motion due to both joint, tamponade or soft tissue pathology

Both traumatic and elective conditions can lead to restrictive movement, with fractures or dislocations being the most common traumatic cause for loss of motion, secondary pain, and an x-ray making a diagnosis. Or selectively, the most common cause is arthritis, and getting an x-ray would be the first investigation.

PT closure while evaluating hand conditions, a combination of symptoms such as pain, deformity, neurological deficits, instability and left arm motion can help narrow down the diagnostic possibilities. However, having a system to offer the possible diagnoses is extremely valuable. Therefore, the presentation of either a traumatic or an electric presentation, knowing anatomy and understanding the patient's symptomatology provides essential clues for accurate diagnosis and optimal management.

By systematically assessing these symptoms, I hope this can help tailor the physical examination and investigations to arrive at the most appropriate diagnosis, ensuring timely and effective treatment for patients with any conditions. Thanks for listening to me with Bozzie Midhead. I'd like to remind you that all the information presented today is just one opinion and that there are numerous ways of treating all medical conditions. Therefore, you should always seek advice from your health professionals in the area in which you live.

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