The Rule of Threes: Simplifying Complex Hand Conditions in Medicine

Can simplifying complex medical diagnoses be as easy as one, two, three? Join me, Dr Gavin Nimon ( Orthopaedic Surgeon ), as we uncover the secrets of the rule of threes in tackling musculoskeletal hand conditions. Journey through the labyrinth of traumatic, elective, and mixed hand presentations with a new lens that promises clarity for both seasoned practitioners and eager medical students. Discover how categorizing fractures, dislocations, and nerve injuries into structured classifications can transform the way we assess and treat these intricate conditions, making them more approachable and less daunting.

Delve into the world of arthritis, tendon issues, and nerve conditions, and learn how to effectively assess ailments like primary osteoarthritis, rheumatoid arthritis, and carpal tunnel syndrome. From the telltale signs of Heberden's nodes to the vexing symptoms of trigger finger, I offer practical knowledge that translates to real-world medical applications. Whether you're a curious listener or a medical professional, this episode delivers valuable insights into the effective management of hand health, enhancing your understanding and approach to these common yet complex conditions.

(This bepisode was also partially produced on the traditional lands of the Jagera people and the Turrbal - Meanjin (Brisbane CBD) as well as Kaurna Land)

Aussie Med Ed is sponsored by OPC Health, an Australian supplier of prosthetics, orthotics, clinic equipment, compression garments, and more. Rehabilitation devices for doctors, physiotherapists, orthotists, podiatrists, and hand therapists. If you'd like to know what OPC Health offers.

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Chapters

• 0:00 The Rule of Threes in Medicine
• 10:19 Common Hand Conditions and Treatments

Transcript

Dr Gavin Nimon: 0:21

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. Well, 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 about 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 Aussie Med Ed. G'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 Nimon, an orthopaedic surgeon based in Adelaide, and I'm broadcasting from Kaurna Land. 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. I'd also like to remind you that if you enjoy this podcast, please subscribe or leave a review or give us a thumbs up as I really appreciate the support and it helps the channel grow. I'd like to start the podcast by acknowledging the traditional owners of the land on which this podcast is produced, the Kaurna people, and pay my respects to the elders both past, present and emerging. Well, you may have seen my prior podcast on the rule of threes and how it can help you in 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 can 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 diagoses, We can 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 percent of the common things I see as a hand surgeon. And I hope this 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, or revulsions As well as nerve injuries. Therefore, if we categorise the five main traumatic hand conditions, we have fractures, dislocations, infections, tender injuries and nerve injuries. Let's start with fractures. When thinking of fractures, we'd start with the bones of bone, that being the distal radius and ulna, or the carpal bones, or the metacarpals and phalanges. If we look at the distal radius and ulnar, when we 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 Colle's fractures, where there's dorsal displacement of the wrist, or Smith's fracture where there's volar displacement. Or the fractures can be intra articular, such as Barton's fracture, which is a volar intra articular fracture, where the volar fragment is displaced all the way along with the carpus, as well as a radial styloid fracture. We can have grossly commutated 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 fractures of 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 an important injury. And due to his 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 triquetrum, 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 triquetrum. This is really a type of wrist sprain, with an avulsion If we move on to the metacarpal and palangeal fractures, metacarpal fractures often involve 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 and they cut the metacarpal neck, volar flexes. Fractures can also occur at the base of the metacarpal, and this can be like a fracture dislocation pattern, where the bone is tried subluxated at the carpal metacarpal joint and fractured at the same time. Fractures at the base of the thumb are also common, and one that's important is known as a Bennett fracture, which is intra articular, where the fragment stays with the ligaments and the rest of the bone subluxates radial wards. You can also get fracture in the whole base of the thumb as a Rolando fracture, and these can lead to instability and secondary arthritis. Phalangeal fractures involve the distal prolongs of common, and often quite simple, but the phalangeal fractures can be more complicated if they're involved with the joint surface, particularly around the PIP joint. When looking at dislocations on the hand, these can occur at any of the joint's levels, including carpal dislocations, where you might get a dislocation of the lunate bone, or the bones around the lunate called perilunate. These are considered surgical emergencies because the bones then push up the median nerve and can lead to compression of the nerve and also vascular compromise. Because of the number of bones involved in the carapace, it's often difficult in interpreting x rays and they can be easily missed. It's important you're aware of them and be checked for the four C's on the lateral x ray of a wrist. That being the distal surface of the radius, the proximal surface of the lunate, lunate and the proximal capitate. These four C's should all line up in the lateral x ray. These dislocations scaphoid fracture, when you get trans scaphoid peri linear dislocation. When we move on to the metacarpophalangeal joints and interphalangeal joints, these dislocations are particularly common on the sports field, and are often replaced by trainers, but need to be aware of them as well, and may result in swollen hands. Associated with that, you can get an avulsion of the volar plate. It 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 olicolateral ligament of the metacarpopiladial 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 the adductor aponeurosis and doesn't sit back next to the bind in many situations, not all, and that can lead to chronic instability of the thumb and pain and secondary arthritis. The other injury is the scapho-lunate ligament injury, which is a similar injury to fracturing of the scaphoid and really is a minor version of carpal dislocation that we discussed earlier in the start of the plan. Really. Given that the ligament itself can't be seen on x ray, it's often missed. And as people are more concerned about scaphoid fracture, it could actually 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 on the hand can involve bones, joints, or soft tissues. Infections of the joints are called septic arthritis. And the infections of these areas are also considered a surgical emergency. One type of infection that should not be missed is what I call a fight bite, where a laceration occurs over the knuckle, someone punches someone in the face, leading to a cut over the metacarpopalangeal joint. And during this time, it enters the joint, introducing oral bacteria into the joint. Each time there's a tooth wound over a knuckle, you should let it go a full wash out of the wound in surgery. Flexor tendon sheath infections are also quite important because this is another orthopaedic measure because a flexor sheath infection can lead to result in scarring, which leads to stiffness, and because it's a localised compartment, the issue of the localised compartment syndrome associated with it. Therefore, 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 abortion 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 Seddon's Classification or the Sunderland Classification. The Seddon's Classification is easier, and ironically, it is divided up into three main grades. Neuropraxia, Axontomesis and Neurotmesis. Compression injuries, such as those caused by a lunate dislocation or another bone or fractured or pushed out of the median nerve, can lead to acute syndromes 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. 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 like to divide these into three main areas. Primary osteoarthritis, this is the wear and tear variety, often from repetitive use or degeneration of the ears. The more interpalaneal joints, where it's associated with pain. Deformities, particularly seen in middle aged patients and with the developments of Heberden's nerves at the DIP joint and Bouchard's joint, these are the 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 scapho trapezoid or trapezoid joint, STT joint. These lead to pain and reduce group 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 in the joint surface. It 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 arthropathy, and these are systemic in nature and affect multiple joints. As well as other tissues, including tendons, leading to deformities like aorta drift or swan neck deformities, etc. We've covered this a lot previously in an interview with Sam Whittle on the podcast. Now any of these types of arthritis can lead to the production of fluid. Injuries anywhere can lead to the production of fluid, including soft tissues and tendons, but what's more common in joint surfaces 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 tumours or bone cysts, and this will be covered in a separate podcast. But another bone issue which you may not have heard about, but which is worth knowing about, is Keinboch's disease. It's avascular necrosis which occurs spontaneously. If 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, What? And then you might see signs of the, part of the joint collapsing, leading, uh, secondary to the apase necrosis. And that can eventually lead to after ibis. 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 DeQuervain's tenosynovitis. Trigger finger happens when the tendon enlarges and gets caught in the tendon sheath, or flexor sheath, causing the finger to lock, and you might, the patient might have trouble flexing the finger down because it's catching just approximately the A1 pulley in the flexor sheath on the palmar side. Or once it does flex down, yet they might not be able to straighten it out and suddenly they have to force it out straight . DeQuervain's Tenosynovitis similar condition of this that involves inflammation tendons on the right side of the wrist, the first extensor compartment, often with a second repetitive thumb movement. It is 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 intersections where you get pain on the dorsal wrist where the EPL, tendon extensor pollicis longus, crosses over the second extensor tendons, extensor causing pain. And tendinitis in the fourth extensor compartment, that involving the extensor digitorum and with the associated crepitus. Tendonitis can happen just about anywhere in the hand and is often associated with swelling and crepitus when the tendon moves. We move on to nerve conditions, where 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 median nerve is compressed and the carpal tunnel leads to numbness. Tingling, a weakness of the thumb, index finger, and middle finger, and 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, often quite worse than holding a phone or riding their bicycle. You can get similar symptoms affecting the only nerve as well, with paracesia affecting the only nerve, the middle finger, and half the ring finger. If a nerve compression can occur, the glios can now have a wrist that's superficial to the flexor adenaculum. or 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 tunnel syndrome, it's always a good idea to rule out any cervical spine issues as nerve compression further up could be a part, a part to play. As we mentioned previously, nerve entanglement can be a complication of acute traumatic condition. Then we get ligament injuries. Ligament injuries can occur electively, such as chronic stretching, All secondary ligament is laxity, but a more common scenario is a choroid presentation of a prior acute injury. An important type of ligament injury is a scapho-lunate ligament injury, secondary to trauma or delayed presentation. This is what we discussed earlier, but when left untreated, this can lead to scapho-lunate advanced collapse, which can cause long term instability and lead to secondary arthritis in the wrist. Patients often report a clunking feeling when they're gripping or loading the wrist and then they get pain. Scaphoid fracture non unique also leads to this scenario as well. This is known as scaphoid non unique 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 ulna, what's known as the ulna fovea. And as the hand supinates and pronates, the radius swings around the tip of the ulna along this soft tissue envelope. It can lead to injuries, but on bulls, when the ulna doesn't fracture, this ligament can tear. It often tears as we 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 will present with ulnar sided pain and definitely with supination and pronation of a wrist. And it may cause a clicking sensation. This is something we keep aware of as well. Finally, we move on to those miscellaneous groups of conditions that don't fit neatly anywhere. These include benign and malignant tumours, congenital issues, and certain soft tissue problems. I intend to discuss tumours in a later podcast, but I think there are two conditions worth going down. The first is Dupuytren's contracture. This is a genetic condition where the palmar passive thickens leading to Gradual bending of the fingers, particularly the ring of little fingers over time. This makes it difficult to fully straight the hand out and the hat, the fingers get stuck in the palm as it slowly gets worse. Once you've seen a Dupuytren's contracture is pretty obvious. Giant Cell tumor of tend sheets. Another benign type of tumor, which is a nodular growth on the tend sheet. It often looks like a ganglion, but tends to be firm and doesn't fluctuate in size like ganglion be. 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, but I'm sure there are other conditions that may have been missed. This covers 95 percent 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 and hand conditions. The most important thing is, 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 could help target specific diagnoses. Starting with pain, it's a common symptom both in traumatic and elective presentations. Nor from the primary reason patients seek medical attention. The location, type and duration of the pain can provide critical 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. The 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 the likely presentation of pain, arthritis and tendinitis are the most common diagnoses for the possible rare presentation of avascular necrosis or instability. Once again, a site of pain can help you assess where the condition is arising, and if associated with cryptis, the site of origin will also assist. In primary osteo arthritis, patients may experience a deep aching pain, a pain While conditions such as DeQuervain's tenosynovitis will cause pain when the attendant is stretched or moved. For the latter, fixation is excluded afteritis and ultrasound can confirm attendant itis. 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 as in dislocation of the metacarpo-phalangeal joint, are usually easily seen, whilst the inability to extend or flex the joint suggests tendon injury. In an elective scenario, rheumatoid arthritis can lead to classic deformities, such as swan necking and boutonniere 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, X 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 Dupuytren's contracture will get progressive flexion and deformity 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 symptoms such as numbness, tingling or weakness are often pointed towards compression or injury. These symptoms can be seen in both acute traumatic conditions as well as chronic repressive syndrome. The trick here is to diagnose the correct nerve affected and exclude other causes such as cervical radiculopathy. The appropriate investigation here would be nerve conduction studies. And I've recently done a podcast with Jessica Hafner on peripheral neuropathy. Instability or joint or ligament instability can be a sign of both traumatic and elective conditions. Often leading to recovery injuries or long term dysfunction. This is where x rays will help diagnose chronic pathology, consistent with elective presentation 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 ulnar. Patients finally may present with lack of motion due to both joint, tendon 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, technically pain and an x ray making a diagnosis. whilst electively, the most common cause is arthritis and getting an x ray being the first investigation. In conclusion, while evaluating hand conditions, the combination of symptoms such as pain, deformity, neurological deficits, instability, and lack of motion 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 lengthy 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 pain conditions. Thanks for listening to me, the Aussie Med Ed. 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. Also, if you have any concerns about the information raised today, please speak to your GP or seek assistance from health organisations such as Lifeline in Australia. Thank you very much for listening to our podcast today. I'd like to remind you that the information provided is just general advice and may vary depending on the region in which you are practising or being treated. If you have any concerns or questions about what we've discussed, you should seek advice from your general practitioner. I'd like to thank you very much for listening to our podcast and please subscribe to the podcast for the next episode. Until then, please stay safe.