When cracking your knuckles, one tends to hear a “pop” noise that is loud, sharp, and irritating to most. This noise can be addicting in the sense that it makes others want to crack their knuckles. The main questions that I focused my research on were “Does cracking your knuckles or joints cause potential health issues for your future?” and “ Why does cracking a joint such as your knuckles make a “pop” noise?”Continue reading “Why Do Your Fingers Make A “Pop” Noise When You Crack Your Knuckles?”
While regenerative medicine may not be time travel, recent research advances have given hope for using scaffolds as a potential treatment for osteoarthritis, a common form of arthritis.
Scaffolds for Cartilage Regeneration
3-dimensional structures called scaffolds can be designed to foster the growth of cartilage in areas where it has worn down, such as the areas within the body suffering from arthritis. These scaffolds are designed to imitate the natural properties of human cartilage, most importantly, the stiffness. Additionally, in order for new cartilage to be able to grow within these scaffolds, pores are incorporated to allow for necessary nutrients to flow and growth to occur. The ability for water to flow through the scaffold, or the permeability, is a mechanical property utilized as a way to measure the potential nutrient flow through and cartilage ingrowth into the scaffold. Research on the manufacturing processes of these scaffolds provides information on how to achieve the necessary stiffness and permeability of the scaffold so that it is as similar as possible to that of natural cartilage.
Making the Scaffolds
Multiple techniques for making scaffolds are considered: Freeze-Extraction Porogen Leaching and 3D Fiber Deposition. For both of these methods, mechanical testing was conducted to conclude what design parameters affect the properties of the scaffold. There exists a correlation between the stiffness of the scaffold and the porosity; that is, a greater porosity corresponds to a less stiff scaffold. Freeze Extraction Porogen Leaching consists of mixing the scaffold material with a porogen material and freezing the mixture to create a distribution of pores after the porogen is removed. A higher porosity, and consequently higher permeability but lower stiffness, can be achieved by increasing the content of the porogen.
3D Fiber Deposition is an additive manufacturing process similar to 3-D printing which extrudes the scaffold layer-by-layer according to a predesigned model which allows for the distribution, size, and amount of pores to be explicitly defined. Various parameters of this process can be changed to produce different scaffolds. Increasing the size or amount of pores increases the permeability but decreases the stiffness of the scaffold, similarly to Freeze Extraction Porogen Leaching. Additionally, the thickness of each layer, orientation of each new layer relative to the previous layer, and size of the fiber being extruded can be altered to achieve the same trends in porosity.
Implementing the Scaffolds
So how exactly are these scaffolds used to turn back the clock on cartilage deterioration? Scaffolds can be seeded with stem cells and inserted into the area of the body where cartilage has worn down. Finite Element Analysis has modeled the insertion of a scaffold into a defected area, proving the effectiveness of the scaffold at regenerating cartilage when the properties of the natural cartilage are achieved by the scaffold. Cartilage stiffness varies depending on the location within the body, suggesting the importance of being able to tailor these scaffolds to have varying properties and motivating the study of trends between design parameters and material properties.
Rheumatoid arthritis (RA) is a chronic autoimmune disease that, according to the Arthritis Foundation, affects 1.5 million people in the US. Women are 3 times more likely to develop RA and are usually diagnosed between ages 30 and 60, while men are rarely diagnosed before the age of 45 . Unlike osteoarthritis which is caused by wear and tear on joint cartilage over time, RA is caused by an overactive immune system that triggers unnecessary inflammation responses. One effect of this is that the body attacks its own joints causing swelling, stiffness, and chronic joint pain as well as irreversible damage. This limits joint mobility and decreases the quality of life for those impacted by it, especially those diagnosed as children or young adults.
This disease cannot be cured but treatments like medicine or dietary/ lifestyle changes are most effective when diagnosis happens early. When joint damage occurs it is irreversible, meaning the only treatment option is surgery. The joints most commonly affected in the early stages of this disease are finger joints which are usually the first sign of inflammation and will be the focus of this article. The image below shows the progression of finger joint damage in a patient with RA starting with no damage (a) to severe damage (c).
As an RA patient, a typical visit to your doctor would always include a pain/inflammation assessment. With a focus is on early stages of RA, fingers and hands would be the most important areas to look at. Each joint of focus would be felt by your doctor to check for swelling and tenderness, but the most important aspect is the patient’s self-assessment of inflammation and pain. It is important for patients to accurately assess their pain and mobility in order to find a medicine or treatment that works effectively. This was the focus of a study that was conducted on 52 RA patients (33 women and 19 men) which used a variety of tests in an attempt to quantify arthritis damage and compare it to the predictions made my patients.
The first test looked at range of motion for fingers flexed (in a fist) and extended (straightened). The next test measured grip strength in different positions like using a pencil, opening a jar or turning a key by using a device that measured the force produced by the hand in each position. Stiffness was measured visually, and pain levels were also recorded, but it should be noted that pain cannot accurately be quantified because pain tolerances vary among patients. The result of this study was that the patients predictions on grip strength and stiffness best correlated to the real results and were therefore the best predictors of hand function. This means that patient reports of strength and stiffness are the most accurate and helpful to be used by doctors when choosing medications or treatment plans.
Because joint damage from RA cannot be reversed, surgery is usually the only option to repair damaged joints, and even surgery will not bring back full mobility. Because RA treatments (both medicines and surgery options) are still very new there isn’t widely available or reliable data on the impact of hand surgery. Additionally, with the increasing use of the newer class of biologic drugs there has been a noticeable decrease in damage to the synovial tissue (the specialized tissue between the bones in any given joint) and the need for hand surgery has significantly decreased because of this. Overall, a variety of surgeries are available and there is almost always a tradeoff between mobility, vanity and elimination of pain. It is up to the patient, doctor, and surgeon to decide the best treatment option.
Overall, it is important to listen to your body and look out for early signs of RA to avoid lasting joint damage. This is especially important if you have a family history of RA. Early symptoms include, redness, pain, stiffness and swelling at joints, a lack of muscle strength, decreased range of motion/mobility, and even unexplained fatigue or fever.
References and Further Reading
How does someone go from being the youngest NBA MVP one year to barely making headlines the next? Ask Derrick Rose. After being named the youngest MVP in the NBA, Derrick Rose tears his ACL the next year and then tears his right meniscus twice in the span of three years. Knee injuries have not been kind to Derick Rose, but how does one tear their meniscus and how does it get repaired?
The meniscus is shown in Figure 1.
According to Sports Health, the meniscus is a type of cartilage that provides cushioning between the bones in the knee. The meniscus main role is to absorb shock and the impact on the leg and knee when it is in motion. It allows for stability and smooth motion between the joints.
In a game of basketball, one of the biggest sports in the United States, there is plenty of running, jumping to shoot the ball into the basket, jumping up to catch a rebound, and doing sharp cuts during the game to shake off a defender. All these movements cause high loading on the knee, and if there is an over-rotation on the knee during these movements, then it can cause a tear in the meniscus. The video below shows when Derrick Rose tore his meniscus.
In the video, it shows Derrick Rose doing a relatively easy movement, he plants his foot in order to change direction to chase after the ball. It is a non-contact movement, but due to an awkward landing on his foot, he gets injured and misses games for the rest of the season.
When the meniscus is torn, there are two options in terms of healing the tear. The options are getting the meniscus removed or getting it repaired. Both options have their own recovery time. If you get the meniscus removed, then the recovery time would be from four to six weeks. However, there are setbacks to getting the meniscus removed such as leading to early arthritis. If the meniscus is repaired, then the timetable to return to play is around six months. According to USA Today , he chose to get the meniscus repaired in order to not have future complications around his knee, which is why he had to sit out for the rest of the season. Going this route also gave Derrick Rose the chance to return to his playing form before injury. According to Stein, 96.2% of athletes that undergo meniscal repair go to pre-injury level of activity after the repair, which is good news for Derick Rose.
However, Derrick Rose tore his meniscus again the following season in 2015. He would then have surgery to remove the damaged part of the meniscus and would return in a couple of weeks. This would then be his third surgery to repair his knee, and his surgeries must have an effect on his playing performance. After these surgeries, the world waits to see if Derrick Rose can reach MVP status again during his career. It would be tragic to see that these knee injuries would ruin someone’s career.
Sources and Additional readings:
Canine hip dysplasia (CHD) is a degenerative hip disease that tends to develop in large breed dogs, such as the Bernese Mountain Dog, affectionately referred to as Berners. CHD significantly decreases the quality of life of a dog and often leads to complete immobility if left untreated. Experts estimate that about 28% of Berners are affected by dysplastic hips, making them the 8th most susceptible dog breed.
At birth, puppy skeletal structures are largely composed of cartilage that is much softer than bone. This softer cartilage is able to adapt much more easily to the rapid growth that occurs during the early months of a dog’s life. In their first few months, Berners will typically gain 2-4 pounds per week, which adds increasingly large stresses to their developing bones and joints. While genetics play a large role in the susceptibility of a dog to develop CHD, the loading cycles and forces on the cartilage greatly shape the development of the dog’s hip.
The hip is a ball and socket joint, where the head of the femur, the very top of the dog’s leg, should fit perfectly into a socket in the pelvis. If the ligaments that hold the femur in the hip socket are too weak or damaged at all, the positioning of the
hip joint will be off and the hip will be subjected to unbalanced forces and stresses over the course of the dog’s life. The distribution of forces experienced by the hip joint in normal hips is evenly spread, while dysplastic hips are subjected to a stress concentration on the tip of the femur. These unnatural forces will cause laxity in the hip joint, leading to instability, pain, and often times the development of osteoarthritis.
There are also a number of environmental factors, many of which are inherent to large dog breeds, that dramatically increase a dog’s susceptibility to CHD. A study by Dr. Wayne Riser concluded that factors such as oversized head and feet, stocky body type with thick, loose skin, early rapid growth, poor gait coordination, and tendency of indulgent appetite all contributed to the development of CHD. All of these features are generally inherent to large breed dogs, such as Berners, so great care must be taken in order to mitigate their effects on the quality of life for these dogs.
Multiple studies have shown that treatment that is implemented early in the dog’s life is much more effective than late-in-life treatments. CHD warning signs can be seen in puppies as young as 4 months old, and most veterinary professionals agree that if scans occur at 2 years of age, the most optimal time for treatment has passed. Since larger stresses will be put on the hip joint as the dog grows, surgical repairs, or changes in diet and exercise, are most effective if implemented before the dog’s skeletal frame is completely developed.
Don’t knee problems only plague old people or people who have run for a lifetime? I questioned this when, for the seventh time in a row, my knee was hurting only a mile and a half into my run. I’m too young for this! However, a plethora of information suggests that knee pain is perhaps not so uncommon in younger runners and athletes as I thought.
The American Family Physican published an article detailing one form of knee injury informally called “Runner’s Knee”. A shockingly high number, between 16 and 25 percent, of running related injuries fall into this categorization. Medically termed patellofemoral pain syndrome (PFPS), the ailment manifests in pain or stiffness in the knee, particularly when bent in load-bearing scenarios such as walking, running, jumping, or squatting. The patellar region experiences shocking loads even in the day to day: in walking alone the region experiences up to a half the person’s body weight while in an activity like squatting it can experience up to seven times one’s body weight. Often the pain is hard to pinpoint but occurs in or around the front of the knee within a circular range. It can inhibit or put a stop to training, however, if addressed early on, can often be healed or corrected much more quickly.
In PFPS, the patella (the kneecap) moves abnormally within the groove on the end of the femur (called the femoral trochlear groove) due to imbalanced or unusual loads on the joint. This results in over-stressing the joint and causing pain. Several possible causes exist for PFPS; here, I will focus on three of most commonly cited: increased intensity of activity, weak hip muscles, and overpronation.
One review explored that women are more likely to suffer from PFPS. In this study they saw that women of higher activity levels were not necessarily more likely to experience pain due to PFPS than women who had a lower activity level. Rather, a substantial increase in activity level seemed to be the cause of pain. Therefore, more than overuse of muscles or joints, PFPS often develops with increased amounts of activity, or temporary overuse, such that the body is not prepared to handle the increased and repetitive forces on the knee.
Weakness in Hip Muscle Strength
This study shows that lower extremity mechanics and motion can be affected by hip strength. For example, inward rotation of the hip can be lessened through strengthening of hip muscles that counteract that rotation. With less internal hip rotation, the knee abduction moment (the tendency of the knee, due to reaction forces from the ground, to rotate inward and away from the balanced midline of the knee joint) decreased which often resulted in less stress in the knee. Therefore, the review suggests that strengthening hip muscles can lower the patellofemoral joint stress and help treat PFPS.
Pronation refers to the natural movement of one’s foot and ankle slightly inward while stepping. When the ankle rotates too far inwards, it is called overpronation. Overpronation can lead to further improper structural alignment in the lower body as the tibia rotates improperly in response to the ankle rotation. The tibia’s rotation then disrupts the natural movement of the patellar joint and can contribute to PFPS. In many cases, overpronation can be corrected through use of orthotic shoe inserts that prevent the over-rotation of the foot and ankle.
In conclusion, while we may often associate knee problems with older people or arthritis, PFPS affects many athletes, particularly runners, at any age. Often, proper training programs that do not accelerate activity too quickly, strengthening exercises that focus on the hip muscles, and proper, overpronation-correcting footwear can treat or prevent an individual from being affected by PFPS. Check out some strengthening exercises here.