Thiemann disease, familial form, is a very rare inherited joint and bone condition that usually affects the fingers and sometimes the toes. Early signs of Thiemann disease often appear in late childhood or the teen years and can include swelling, stiffness, pain, and slowly changing finger shape. The condition is usually lifelong, but not everyone will have the same experience. Thiemann disease does not usually affect life expectancy, but many living with Thiemann disease can have ongoing hand discomfort and trouble with fine tasks such as writing or opening jars. Treatment focuses on managing pain and protecting joint function, often with pain relief, hand therapy, activity changes, and follow-up with a specialist.
How many people live with Thiemann disease, familial form?
There is no direct headcount for familial Thiemann disease, but Orphanet classifies it as affecting fewer than 1 in 1,000,000 people (Orphanet, 2024), which suggests fewer than about 8,100 people worldwide (United Nations, 2024; estimate based on Orphanet, 2024). Using that same upper-bound estimate, fewer than about 340 people may be living with it in the United States (U.S. Census Bureau, 2024; estimate based on Orphanet, 2024).
Overview
Thiemann disease, familial formSymptoms
Thiemann disease, familial form, usually causes swollen finger joints, especially near the fingertips, with stiffness, reduced movement, and fingers that gradually look shorter or crooked. Signs often begin in childhood or the teen years and can also affect the toes.
Outlook and prognosis
For many living with familial Thiemann disease, finger swelling, stiffness, and shape changes often progress during the teen years, then stabilize. Overall health and life span are usually normal, though some people have lasting hand discomfort or reduced motion.
Causes and risk factors
Familial Thiemann disease is linked to an inherited genetic change, though the exact gene is often unknown. Risk is highest when it runs in a family; lifestyle and environmental factors are not known to cause it.
Genetic influences
Genetics likely play an important role in familial Thiemann disease, because it can run in families. Inheritance is often thought to be autosomal dominant, meaning one altered gene copy may be enough, but the exact genetic cause is still not clearly defined.
Diagnosis
Diagnosis of familial Thiemann disease usually starts with the pattern of finger and toe changes, exam findings, and hand or foot X-rays. Doctors may confirm it with family history and, in some cases, genetic tests.
Treatment and drugs
Familial Thiemann disease is usually managed by easing joint pain and protecting finger function. Doctors may suggest anti-inflammatory pain relief, splints, and hand exercises. Surgery is uncommon, but may help severe joint deformity or stiffness.
Symptoms
Changes often show up in the fingers during late childhood or the teen years, when schoolwork, sports, or music can make hand stiffness easier to notice. For many people with the familial form of Thiemann disease, the early features of Thiemann disease are swelling around the finger joints and trouble bending them fully. Pain is often mild or comes and goes, but the shape and motion of the fingers can slowly change over time.
The finger joints, often the middle ones, can look puffy or enlarged. Rings may feel tighter, and the fingers can seem broader even when pain is minimal.
Affected fingers may feel stiff, especially after rest or first thing in the morning. Everyday tasks like buttoning clothes, typing, or gripping a pen can take more effort.
Some people with Thiemann disease cannot fully bend or straighten certain fingers. This reduced movement may become more noticeable during writing, sports, or playing an instrument.
Aching, tenderness, or soreness can happen, but the discomfort is often mild and may come and go. Day to day, it can feel like the hands get irritated after heavy use.
How people usually first notice Thiemann disease, familial form?
The first signs of familial Thiemann disease are usually noticed in late childhood or the teen years, when one or more finger joints begin to look enlarged, especially near the middle and end joints, and the fingers may slowly start to curve or seem unusually stiff. Many people with Thiemann disease do not feel severe pain at first, so it is often first picked up because families notice a change in finger shape or because a doctor sees swelling and limited movement during an exam or on hand X-rays. Because it tends to run in families, how Thiemann disease is first noticed is often shaped by that family history, with relatives recognizing that the hand changes look similar to what other family members developed.
Types of Thiemann disease, familial form
Thiemann disease, familial form, is a rare inherited bone condition that mainly affects the end parts of the finger and sometimes toe bones. In practice, doctors do not use well-established clinical variants for it, and the condition is usually described by the pattern and severity of bone changes rather than by separate subtypes. At this point, no distinct types of Thiemann disease are widely recognized.
Can I slow down the onset of symptoms?
For familial Thiemann disease, there is no good evidence that lifestyle changes or medical treatment can meaningfully delay when symptoms start. Because it is a rare inherited condition that affects the small bones and joints, things like diet, exercise, vitamins, or other habits have not been shown to prevent the condition, although avoiding repeated hand strain and getting early care may help with swelling, stiffness, and pain after symptoms begin; there is also no well-established preventive medicine or screening plan that is known to stop onset. Even so, regular follow-up with a bone or joint specialist can still be worthwhile, because early support may help protect hand function and make day-to-day symptoms easier to manage.
What genetics can tell you about symptoms
In the familial form of Thiemann disease, genetics can sometimes help explain why the condition runs in a family and why symptoms often start in late childhood or the teen years, usually with swelling, stiffness, or changes in the finger joints. In some families, changes in a gene called TRPV4 have been linked to this type of hand bone and joint problem, and these genetic differences may influence which joints are affected and how mild or severe the changes become. Even so, genetics cannot yet predict symptoms with certainty, because people in the same family can still have different patterns and degrees of symptoms.
Causes and risk factors
Familial Thiemann disease is mainly caused by a gene change that runs in a family, and changes in the TRPV4 gene have been found in some affected families. The strongest risk factor is a family history of Thiemann disease. Some risks are written in our DNA, passed down through families. Age also matters, because the early symptoms of Thiemann disease often begin in childhood or the teen years. Lifestyle, diet, and everyday activities do not cause familial Thiemann disease, but hand injuries or repeated joint strain may make symptoms more noticeable in someone who already has the genetic risk.
What are the most common causes or risk factors?
Familial Thiemann disease is mainly caused by an inherited gene change that affects the small bones and joints, so the biggest risk factor is having a parent or other close family member with the condition. In many families, a child can develop it if just one parent carries the changed gene, and there are no well-proven lifestyle, diet, injury, or environmental causes.
Environmental and biological risk factors
Familial Thiemann disease is extremely rare, so scientists have not identified many confirmed environmental or body-based risk factors. Doctors often group risks into internal (biological) and external (environmental). When people look for risk factors for familial Thiemann disease, the clearest finding is that common outside triggers have not been proven.
No specific chemical, infection, injury, or everyday exposure has been proven to increase the chance of familial Thiemann disease. Because so few families have been studied, the lack of proof does not completely rule out every possible influence.
No well-established link has been shown with routine maternal illness, diet, or common medication exposure during pregnancy. Harmful exposures in pregnancy can affect development in general, but they have not been confirmed as a cause of familial Thiemann disease.
Prematurity, low birth weight, and delivery complications are not recognized risk factors for familial Thiemann disease. At this time, there is no consistent evidence that birth events make this condition more likely.
Reported cases include both males and females, and no reliable sex-based pattern has been established. This means sex is not considered a proven biological risk factor.
Genetic risk factors
Inherited factors are the main reason familial Thiemann disease appears in some families. When doctors look at the genetic causes of familial Thiemann disease, changes in a gene called TRPV4 are the best-known finding, although not every family has an identified gene yet. Some risk factors are inherited through our genes. In families where it is passed down, the pattern is often dominant, meaning one altered copy of the gene can be enough to increase risk.
TRPV4 changes: Changes in TRPV4 have been found in some families with familial Thiemann disease. This gene helps regulate cartilage and bone development around the ends of small bones.
Family history: Having a parent or close relative with familial Thiemann disease raises the chance that it runs in the family. Sometimes the pattern only becomes obvious when several relatives compare similar finger or joint changes.
Dominant inheritance: In many reported families, one altered copy of the gene is enough to pass on risk. If a parent carries the change, each child has a 1 in 2, or 50%, chance of inheriting it.
Variable expression: People in the same family can be affected differently, even when they share the same genetic change. One relative may have mild finger changes, while another may develop earlier or more noticeable joint problems.
Unknown genes: Some families with Thiemann disease do not yet have a confirmed gene identified. This suggests that other rare inherited gene changes may also cause the condition.
Lifestyle risk factors
In the familial form of Thiemann disease, lifestyle habits do not cause the condition, but they can influence pain, stiffness, hand and foot function, and the pace of secondary joint wear. Because this disorder mainly affects the small joints, daily patterns of loading, movement, and recovery can matter more than broad generic wellness advice. Evidence is limited because the condition is rare, but clinicians still use practical principles from joint protection and musculoskeletal care to guide how lifestyle affects Thiemann disease.
Frequent gripping, pinching, tool use, or high-force hand tasks can increase pain and swelling in already affected finger joints. Pacing activity, using larger grips, and taking regular breaks may reduce flare-ups and protect function.
Too little movement can worsen stiffness and reduce range of motion, while heavy impact or forceful joint loading may aggravate symptoms. Gentle strengthening, stretching, and low-impact aerobic exercise may help maintain mobility without overloading vulnerable joints.
Extra body weight does not cause Thiemann disease, but it can increase stress on affected toe and foot joints and make walking pain worse. Keeping weight in a healthy range may lower mechanical strain and improve day-to-day mobility.
Smoking can impair blood flow, tissue repair, and bone health, which may worsen joint discomfort and recovery after overuse. Avoiding tobacco is one of the more important lifestyle risk factors for Thiemann disease when the goal is to limit secondary joint damage.
Risk prevention
If Thiemann disease runs in your family, there is usually no proven way to fully prevent the condition itself because the risk is tied to inherited genes. In practice, prevention is more about lowering the chance of pain, stiffness, joint injury, and long-term hand or foot problems in people living with Thiemann disease. Some prevention also centers on family planning and early monitoring, especially when early symptoms of Thiemann disease start in childhood or the teen years. Prevention is flexible—it adapts to your life and health background.
If Thiemann disease is known in a family, genetic counseling can help you understand who may be at risk and what inheritance may mean for children. This can support informed family planning and earlier evaluation when symptoms appear.
Regular follow-up with a clinician can help spot changes in finger, thumb, or toe joints before they cause bigger daily problems. Prevention works best when combined with regular check-ups.
Repeated heavy gripping, forceful pinching, and high-impact strain on small joints may worsen pain or stiffness over time. Using supportive tools, pacing hand tasks, and taking breaks can help protect joints affected by Thiemann disease.
Hand and foot injuries can add stress to already vulnerable joints and may lead to more swelling or discomfort. Many living with Thiemann disease do better with safer sports choices, well-fitted shoes, and prompt care for sprains or finger injuries.
Can you prevent Thiemann disease, familial form?
Because familial Thiemann disease is an inherited condition that runs in families, there is no known way to prevent it with diet, exercise, or other lifestyle changes. If it runs in your family, talking with a genetics specialist can help you understand the chance of passing it on, but it cannot fully prevent the condition.
Transmission
Familial Thiemann disease is not contagious, so it cannot spread from person to person through the air, touch, food, or everyday contact. Instead, how Thiemann disease is inherited is the key issue: in affected families, it is thought to often follow an autosomal dominant pattern, which means a parent with the gene change may pass it on to a child.
Many living with familial Thiemann disease have relatives with similar finger or toe joint changes, but the condition can look milder or more noticeable from one family member to another. Because this is a very rare disorder, a genetics specialist can help explain the chance of it being passed on in a specific family.
When to test your genes
Consider genetic testing if several relatives have had childhood or teen onset swelling, stiffness, or shape changes of the finger or toe joints, especially when the diagnosis is unclear. Testing can help confirm an inherited cause, separate it from look-alike conditions, and guide family counseling and monitoring.
Diagnosis
Symptoms often begin with slowly changing finger joints, such as stiffness, swelling, or fingers that seem to look broader over time. The diagnosis of Thiemann disease usually comes from the pattern of joint changes, especially in the hands and sometimes the feet, together with imaging findings. It’s natural to worry when symptoms don’t have a clear explanation.
Doctors ask when joint changes began, which fingers or toes are affected, and whether pain, stiffness, or reduced movement has been getting worse. This helps them tell Thiemann disease from more common causes of swollen finger joints.
The clinician looks closely at the end and middle finger joints for swelling, thickening, tenderness, and limited motion. They also check whether the pattern is fairly symmetric and whether other joints seem involved.
X-rays are one of the main tools used in how Thiemann disease is diagnosed. They can show characteristic changes in the small bones near the finger joints, such as flattening, irregular bone shape, or early joint damage.
If toes are affected, X-rays of the feet may also be helpful. Similar bone and joint changes can support the diagnosis when hand findings alone are not the full picture.
How is Thiemann disease, familial form diagnosed?
Doctors usually diagnose familial Thiemann disease by the pattern of symptoms and joint changes, especially in the fingers and sometimes toes, along with a family history and X-rays that show typical changes at the ends of the bones near the joints. Blood tests may be done to rule out more common problems, such as inflammatory arthritis, because there is no single routine blood test that proves this condition. In some families, genetic testing can help support or confirm the diagnosis, but it is usually used alongside the exam and X-ray findings, not instead of them.
Stages of Thiemann disease, familial form
Thiemann disease, familial form does not have defined progression stages. This is because it is usually described by when symptoms begin and which finger or toe joints are affected, rather than by a standard step-by-step worsening pattern over time. Doctors usually start with a conversation about joint pain, swelling, stiffness, and changes in hand function, especially when the early symptoms of Thiemann disease begin in the teen years. Diagnosis is usually based on the pattern of symptoms, a physical exam, family history, and imaging such as X-rays to look for the typical bone and joint changes.
Outlook and prognosis
The outlook for familial Thiemann disease is generally favorable in terms of survival, because it is usually confined to the small joints of the hands and feet and is not known to affect life expectancy. Symptoms often begin in childhood or adolescence and may progress slowly over years, with persistent swelling, stiffness, reduced range of motion, and gradual bony deformity in some people. Pain is often mild to moderate, but hand function can become limited, especially when multiple interphalangeal joints are involved. The severity is variable even within families, so some people remain only mildly affected while others develop more noticeable functional impairment. There are no well-established reports of increased mortality from familial Thiemann disease itself, and prognosis is driven mainly by the degree of joint damage and its effect on daily activities.
Long-term effects
For many people with familial Thiemann disease, the main long-term effects involve the fingers and sometimes the toes, especially after the growth years. Changes often begin in adolescence and may leave joints looking broad, shortened, or slightly bent, even if day-to-day discomfort is limited. Long-term effects vary widely, but familial Thiemann disease is often more about lasting shape and movement changes than serious illness affecting the whole body.
The small joints of the fingers, and less often the toes, may stay visibly enlarged over time. Many living with familial Thiemann disease notice that rings fit differently or finger joints look wider than expected.
Stiffness and a reduced range of motion can persist into adult life. This can make fine hand tasks, such as gripping small objects or straightening the fingers fully, more difficult for some people with Thiemann disease.
Some fingers or toes may end up slightly shorter than usual because the bone ends develop differently during growth. This is one of the long-term features that may follow the early symptoms of Thiemann disease.
Affected digits can gradually develop a bent or angled appearance. For many, this is mild, but in others it can become a lasting hand shape difference.
How is it to live with Thiemann disease, familial form?
Living with familial Thiemann disease often means growing up with swelling, stiffness, and gradual shape changes in the finger joints, especially in the middle joints of the hands, which can make writing, buttoning clothes, gripping tools, or playing instruments more awkward. For many, pain is mild or absent, but the visible changes and reduced hand flexibility can still be frustrating, especially during school, work, or social situations. Around you, family members may need to help with some hand-heavy tasks and may also wonder about their own risk, since this form can run in families, but many people continue to lead active, independent lives with the right support and practical adjustments.
Treatment and drugs
Thiemann disease, familial form is usually treated by focusing on symptoms and protecting hand function, because there is no medicine that reverses the underlying bone changes. Many people with Thiemann disease do well with simple measures such as activity changes, hand exercises or therapy, splints if a joint needs support, and pain relief medicines like acetaminophen or anti-inflammatory drugs when symptoms flare. Treatment often looks different for each person, since some have mild stiffness or swelling while others develop more pain, reduced motion, or joint wear over time. If Thiemann disease becomes more severe, a hand specialist may consider procedures to improve function or treat damaged joints, but surgery is not needed for most people.
Can you cure Thiemann disease, familial form?
No, there is no cure for the familial form of Thiemann disease at this time. Treatment does not remove the condition, but it can help ease pain, reduce stiffness, and support hand and foot function with things like pain relief, splints, hand therapy, and sometimes surgery if joint damage becomes severe. For many living with Thiemann disease, care is mainly about managing symptoms and protecting the joints over time.
Non-drug treatment
Daily life with Thiemann disease, familial form, often centers on stiff, sore finger joints that can make writing, typing, buttoning clothes, or opening jars more tiring. There is no single non-drug treatment that fixes the underlying bone changes, so care usually focuses on protecting joints, easing pain, and keeping hands and feet working as well as possible. Managing this condition often means combining therapy, home strategies, and regular follow-up rather than relying on one approach alone. Not every approach works the same way for everyone, especially because symptoms and joint changes can vary from person to person.
Hand therapy can teach gentle exercises and practical ways to reduce strain during daily tasks. For many, treatment begins not at the pharmacy, but with learning easier ways to grip objects, pace activities, and protect sore joints.
Gentle range-of-motion and stretching exercises may help keep affected fingers or toes from becoming even stiffer. These exercises should stay comfortable, because pushing through pain can sometimes make symptoms worse.
Joint protection strategies focus on using larger, stronger joints when possible and avoiding repeated pinching or heavy gripping. Simple routines—like taking short breaks or switching tools—can have lasting benefits.
Soft or custom splints may help support painful joints during certain activities or rest. Some non-drug options are delivered by specialists, and a hand therapist can help decide when a splint may help and when too much support could increase stiffness.
Your genes may have an impact on how drugs work for you
For people living with the familial form of Thiemann disease, there is no well-established proof that inherited changes affect how the usual medicines for pain or swelling work in a predictable way. In day-to-day care, treatment is usually based more on symptoms, age, and how much the joints are affected, so one person may get good relief from a medicine while another may need a different approach. As research grows, this may become clearer, but right now doctors do not usually use genetic testing to choose common medicines for this condition.
Pharmacological treatments
For many living with Thiemann disease, familial form, medicines are mainly used to ease joint pain and stiffness rather than change the course of the condition itself. There is no well-established drug that has been shown to stop or reverse the bone and joint changes in Thiemann disease. Finding the right medication can be a process of trial, patience, and adjustment, especially when symptoms flare after writing, typing, or using the hands for long periods.
There is no approved disease-specific medicine for Thiemann disease, familial form. Treatment usually focuses on symptom relief, especially pain in the fingers and hand joints.
Ibuprofen, naproxen, and similar nonsteroidal anti-inflammatory drugs can help reduce pain and stiffness. These are often used when hand joints are sore after activity or during symptom flares, which can be part of the early symptoms of Thiemann disease. Side effects, if they occur, can often involve the stomach, kidneys, or blood pressure, so long-term use should be reviewed with a doctor.
Acetaminophen, also called paracetamol, may help with mild to moderate pain when inflammation is not the main issue. It does not reduce swelling, but some people find it easier on the stomach than NSAIDs.
Diclofenac gel is sometimes used on painful finger or hand joints to give more local relief. This may be useful when only a few joints hurt and people want to limit whole-body side effects from tablets.
Genetic influences
If several relatives have had stiff, enlarged finger joints or shortened fingers, that pattern can point to Thiemann disease, familial form. Family history is one of the strongest clues to a genetic influence. This named familial form has a clear genetic basis: it is linked to changes in the TRPV4 gene and usually follows an autosomal dominant inheritance pattern, so one altered copy from either parent can be enough. TRPV4 helps cartilage and bone respond to growth and everyday physical stress, so a harmful change can affect the small joints of the fingers and sometimes the toes. Even within one family, symptoms can vary, which is why the early symptoms of Thiemann disease may be mild in one relative and more noticeable in another.
Is Thiemann disease, familial form genetic?
Genetics likely play an important role in familial Thiemann disease, because it can run in families. Inheritance is often thought to be autosomal dominant, meaning one altered gene copy may be enough, but the exact genetic cause is still not clearly defined.
Having a genetic risk is not necessarily a diagnosis
Genetic variants are a usual part of human biology, and they are common across the general population. Most do not have a direct effect on health and are simply part of natural human diversity. For many genes, having a variant associated with a condition suggests a possible link rather than a definite diagnosis, especially when several genes and environmental factors are involved. In some cases, though, a single well-characterized variant in a specific gene is enough to confirm a diagnosis.
Pharmacogenetics—how genetics influence drug effects
For many living with Thiemann disease, familial form, treatment is still aimed at day-to-day problems such as finger pain, stiffness, and trouble using the hands, rather than at a specific gene. In some families, genetic changes linked to bone and cartilage development can help confirm the diagnosis, but at this point they usually do not point to a proven gene-targeted medicine. That means treatment for Thiemann disease often relies on symptom relief, such as pain medicines, hand therapy, splints, and sometimes orthopedic care if joint damage becomes more severe. Genetics is only one factor, and there are no well-established pharmacogenetic rules showing that people with Thiemann disease need a different pain drug based on their gene result alone. Still, genetic testing for Thiemann disease may help doctors distinguish it from other inherited hand and joint conditions, which can make treatment decisions and family counseling clearer. If symptoms are changing or standard treatments are not helping, it is worth asking a specialist whether the genetic diagnosis has been fully reviewed.
Interactions with other conditions
For many living with familial Thiemann disease, the main issue is not that it directly causes other illnesses, but that it can look a lot like other joint conditions. Swollen, stiff finger joints and changes on hand X-rays can resemble inflammatory arthritis, especially juvenile forms of arthritis, so early symptoms of Thiemann disease are sometimes mistaken for a different diagnosis. Certain diseases may overlap, meaning doctors may need to sort out whether joint pain is coming from this rare inherited condition or from another problem such as inflammatory arthritis, prior injury, or less commonly an infection. This matters because Thiemann disease is usually not driven by the kind of body-wide inflammation seen in autoimmune joint disease, so treatment plans may differ. In some families, it also shares features with other inherited disorders that affect the ends of the fingers and toes, which can make genetic evaluation helpful when the diagnosis is unclear. If more than one joint condition is suspected, careful follow-up with a rheumatology or genetics team can help make sure nothing important is missed.
How genes can cause diseases
Humans have more than 20,000 genes, each carrying out one or a few specific functions in the body. One gene instructs the body to digest lactose from milk, another tells the body how to build strong bones and another prevents the body's cells from beginning to multiply uncontrollably and developing into cancer. As all of these genes combined are the building instructions for our body, a defect in one of these genes can have severe health consequences.
Through decades of genetic research, we know the genetic code of any healthy/functional human gene. We have also identified that in certain positions on a gene, some individuals may have a different genetic letter from the one you have. We call these hotspots "Genetic Variations" or "Variants" in short. In many cases, studies have been able to show that having the genetic letter "G" in the position makes you healthy, but having the letter "A" in the same position disrupts the gene function and causes a disease. Genopedia allows you to view these variants in genes and summarizes all that we know from scientific research, which genetic letters (Genotype) have good or bad consequences on your health or on your traits.
What other conditions can cause similar symptoms to Thiemann disease, familial form?
Other conditions that can look similar to familial Thiemann disease include juvenile arthritis and other joint inflammation problems, because they can also cause swollen, stiff, painful finger joints. Doctors may also consider hand osteoarthritis, past injury to the finger joints, and rare inherited disorders that affect the growth of the finger bones and can make the fingers look short, bent, or enlarged.
History
Families sometimes first noticed Thiemann disease in a very ordinary way: a child or teenager developed stiff, enlarged finger joints, and an older relative had hands that looked much the same. Long before modern imaging and genetics, doctors were mainly guided by these patterns and by what they could see on exam. Early reports focused on swelling and limited movement in the ends of the fingers, which could look a bit like arthritis but often followed a different course.
Thiemann disease was described in the medical literature in the early 1900s, when physicians began linking these hand changes into a recognizable condition rather than treating them as isolated joint problems. At first, understanding was limited because the condition is uncommon and symptoms can overlap with other causes of finger pain, swelling, or reduced motion. In recent decades, awareness has grown, and better X-rays and broader study of families have helped doctors separate Thiemann disease from more common joint disorders.
As knowledge improved, it became clearer that Thiemann disease often starts in youth and tends to affect the small joints near the tips of the fingers, though the exact pattern can vary from one family member to another. Some people have mostly cosmetic changes, while others may find writing, gripping small objects, or playing an instrument more uncomfortable over time. This variation is one reason the condition was probably underrecognized in the past.
Later research supported that Thiemann disease has a genetic basis in familial cases, but the history of the condition is really a story of careful observation first. Doctors moved from simply describing unusual finger joints to recognizing a distinct inherited disorder with a characteristic pattern on examination and imaging. Knowing this history helps explain why early symptoms of Thiemann disease may still be mistaken for other hand conditions, especially when only one or two joints are involved at the start.