Archives: News

Cracking the Thin Shell Surrounding the Causes of Adolescent Scoliosis

Which came first–the chicken or the egg? Thin bones, or adolescent idiopathic scoliosis (AIS)? According to this study, the answer to the last question seems to be thin bones.

AIS is an abnormal side-to-side curving of the spine that occurs in adolescence. “Idiopathic” means that the cause of the problem is not understood. This study looked closely at the bones of youngsters with AIS to try to understand the condition’s cause. The 24 girls and four boys in this study were between the ages of 11 and 20. Researchers used two different methods to study the bones. Bone density was measured with a scan that uses low-radiation X-rays. Bone samples from an earlier back surgery were also studied using a high-powered electronic microscope.

Although bones seem hard and dull, they are actually very much alive. Bones are in a constant state of change. Osteoclasts are cells that break down bone tissue, while osteoblasts rebuild new, healthy bone. In this study, the microscopic look at AIS bone showed an imbalance in the way bone was being broken down and built up, resulting in abnormal bone growth.

The bone density scan confirmed this as a thinning of the bone, a condition called osteopenia. The bones of all 28 children showed both the imbalance and osteopenia. This is pretty typical of girls with AIS, as they show less bone and lower body height for their ages.

The authors believe that bone thinning was likely one of several factors that led to AIS. Heredity, hormones, and nutrition are also known to contribute to the development of AIS. The authors hope this research contributes to answering the puzzling question about the possible causes of AIS.

The Foundations of Back Pain

Back pain: common, often recurring, difficult to treat. Medical science continues to search for clues about how to predict who will develop chronic back problems later in life.

These authors tried to find predictors for back pain by looking back twenty years. They followed up on more than 6000 Swedish men who had enlisted for the military at age 18, in 1979 and 1980. At that time the men had gotten physical exams and answered questions about their health habits, type of work, and back condition. By the time they were nearly 40 years old, they filled out a questionnaire with the same types of questions.

The authors found that the men who currently had back, neck, or shoulder problems were much more likely to have done heavy work at age 18. They were also more likely to have had everyday back pain when they were younger. Being overweight also related to back pain. So did smoking. The 18-year-olds who smoked more than 10 cigarettes a day were more likely to have back pain in middle age.

This study may not have provided doctors with a clear blueprint of how to predict chronic back pain. But it does suggest that heavy labor, being overweight, and smoking, even at young ages, can lay the foundations for lifelong back problems. 

Epidural Injections Give a Knock-Down Punch to Low Back Pain

Injections of steroids such as cortisone are widely used to ease joint pain. The use of epidural steroid injections in the spine, however, is more controversial.

The spinal cord travels in a tube within the bones of the spinal canal. The spinal canal is covered by a material called dura. The space between the dura and the spinal cordis the epidural space It is thought that injecting steroid medicaiton into this space fights inflammation around the nerves, the discs, and the facet joints of the spine.

These researchers used epidural steroid injections in 50 patients to try to assess the injections’ usefulness. All 50 patients had low back pain, many with pain into their legs (sciatica). All had tried conservative treatments–such as rest, ice, and anti-inflammatory medications–for at least two months without relief. All 50 patients experienced some pain relief soon after the injection. An average of two years later, 68% of the patients had no pain, 12% had less pain than before the injection, and 20% had the same symptoms as before the injection.

The authors conclude that epidural steroid injections may be helpful for some patients who don’t get relief from conservative treatment. They suggest that injections are generally less helpful for patients with degenerative facet joint disease and disc space narrowing, among other conditions. But for many patients, an epidural injection might be just what the doctor orders to knock down the symptoms of low back pain.

Searching for Clues to the Mystery of Cauda Equina Syndrome after Lumbar Disc Surgery

Surgery for lumbar disc herniation is fairly common. As with all other surgeries, there can be complications afterwards. One of the rare complications is postoperative cauda equina syndromei (CES). CES happens when there is pressure or injury to the lower spinal nerves. It can cause paralysis in the legs, along with loss of bladder and bowel control. Doctors aren’t sure why it happens after lumbar disc surgery.

The authors of this article wanted to shed some light on this mystery. Learning the causes of this complication might help doctors identify patients who are at risk. They studied five patients who developed CES after surgery for lumbar disc herniation. All five patients had uneventful surgeries but developed CES soon after surgery. All of the patients needed another operation to relieve the pressure on the spinal nerves. Two patients recovered completely, and the other three improved but still had some leg weakness and a loss of bladder and bowel control.

One theory why CES can happen after lumbar disc surgery is called the venous congestion theory. This is thought to happen when extra swelling builds up and puts pressure on the spinal nerves, leading to CES. 

All the patients had narrowing in the spinal canal before they went into surgery. The authors suggest that the narrower space may have made these patients more susceptible to venous congestion. The narrow space combined with swelling from the surgery may have put too much pressure in the area, causing a shortage of blood to the spinal nerve cells.

The authors consider that people who have narrowing in their spinal canal may be at more risk of CES after a lumbar disc surgery. If symptoms do occur, the authors emphasize that surgery to relieve the pressure should be done within 48 hours of the first operation.

Promising Treatment Found Ineffective for Discogenic Back Pain

About 39% of patients with chronic low back pain have problems that arise from the disc in the spine. Doctors call this condition discogenic back pain. In an earlier study, these authors found that patients were helped by a technique called percutaneous intradiscal radiofrequency thermocoagulation (PIRFT). PIRFT involves putting a needle directly into the painful disc and then using a set radiofrequency for a specific amount of time. The idea is that the heat inside the disc will build up enough to stop the nerves around the disc from sending pain impulses.

This study was designed to test the effectiveness of PIRFT. Researchers chose 28 patients with specific symptoms of discogenic pain in the low back. All patients were tested for pain levels using two different scoring systems, and they filled out a form about their functional abilities. The patients were divided into two groups. The treatment group received a specified PIRFT treatment. The control group got a fake treatment.

The authors then followed up on the patients’ symptoms after treatment. Success was based on whether patients showed at least a 50% improvement in their scores on the first pain questionnaire and if they had at least a two-point drop in pain on the other system.

Eight weeks after treatment, only one patient in the treatment group had a successful result, compared to two patients in the control group. At eight weeks the two groups had no real difference in their pain levels or functional abilities.

Unlike the earlier study, this new research suggests that PIRFT treatment is not helpful in treating discogenic low back pain. However, the authors note that PIRFT might have been successful if the technique had been done differently or if it had been done only in patients with certain types of symptoms. They conclude that more research is necessary to determine the role of PIRFT in treating low back pain.

The Sticky Truth about Taping Knee Caps

Taping the knee has become a standard method of treating pain caused by a poorly aligned kneecap (patella). The idea is that the tape helps hold the kneecap in better alignment. But does the tape actually improve the position of the kneecap? Past research is unclear.

This study involved 16 young women with alignment problems of their patella. Researchers took pictures of the bones of the subjects’ knees using computed tomography (CT). The CT scans were used to see the position of the knee caps before and after taping the knee, and with or without having the subject tighten the quadriceps muscle.

Only four knees showed even a slight improvement in patellar alignment with taping. In the rest of the knees, taping made no difference in alignment at all.

Patellar taping may indeed help ease pain or provide support for the knee cap. But the authors conclude that the benefits from taping do not seem to be from correcting the alignment of the patella.

Time Heals Everything–Except, Apparently, the ACL

Time heals everything. Or does it? A group of orthopedists in Australia set out to discover the relationship between the passage of time after a knee injury and the extent of knee damage. The researchers looked specifically at meniscus and cartilage damage in patients after an anterior cruciate ligament (ACL) injury.

The ACL connects the thigh bone with the tibia in the lower leg. The ACL plays a key role in stabilizing the knee. Injury to the ACL has been tied to damage of the cartilage surfaces and menisci of the knee. When the ACL is injured, the knee may become unstable, putting more strain and wear on these other knee structures.

Using an arthroscope, researchers looked inside the knees of 130 patients with known ACL damage. (All subjects were scheduled for surgery to repair their damaged knee ligament.) The subjects ranged from one month to a couple of years past the initial knee injury.
Researchers found that the more time that passed since the initial injury, the greater the damage to the cartilage and meniscus. Most patients (72%) showed meniscal damage or loss, with an average of three inches of cartilage damage.

To keep these other knee structures from being damaged, the authors conclude that ACL injuries should be surgically repaired sooner rather than later. The researchers caution that these findings may not apply to all ACL injuries, since many don’t require surgery.

Damage to the cartilage and meniscus may also have something to do with how badly the knee was initially injured. And it is possible some of the subjects already had damage to these other knee structures before they injured their ACL. Still, this study shows that the passage of time can do more harm than good.

The Knee Ligament’s Connected to the . . . Spinal Cord?

Ligaments attach bones to bones. The anterior cruciate ligament (ACL) connects the femur to the tibia. In a way, it also connects the knee to the brain, and to the hamstring muscles of the thigh.

Animal research has shown a nerve pathway that goes from the ACL to the spinal cord and back to the hamstring muscles. This is called the ACL-hamstring reflex arc. Recent studies have shown that the human ACL sends nerve signals to the spinal cord. This study was designed to test whether humans also have the ACL-hamstring reflex arc.

Researchers attached electrodes to the hamstring muscles of nine men with healthy knees. They also inserted electrodes into their ACLs. The muscle reactions were then monitored as the ACL was electrically stimulated. The hamstring muscles of all nine subjects had reflex reactions when the ACL was electrically stimulated.

The ACL was then numbed with an anesthetic, and the tests were repeated. The hamstring muscles showed no reaction after anesthesia. These results support the theory that humans also have an ACL-hamstring reflex arc.

These signals that go from the ACL to the spinal cord help keep the knee in safe alignment. This “sixth sense” is called proprioception. Our sense of proprioception alerts the body about the position of its joints and muscles. Research such as this suggests that proprioception may be one of the most important factors in knee function.

New information like this is important. It can help surgeons develop more effective ACL surgeries, and it can help therapists design better rehabilitation programs for their patients with ACL problems.

The Seven-Year Hitch: Osteoarthritis after ACL Reconstruction

Reconstruction of the anterior cruciate ligament (ACL) of the knee is a common surgery. One of the reasons for ACL reconstruction is to prevent the development of osteoarthritis (OA) of the knee. In an attempt to fix the ligament, though, OA can sometimes develop where the patella (kneecap) and femur (thigh bone) meet. This joint is called the patellofemoral joint.

The authors of this study followed up on 100 patients who had undergone ACL reconstruction surgery about seven years earlier. All patients had a follow-up physical examination, answered questions about their pain and function, and had knee X-rays taken. These latest results were compared with the patients’ records from before and just after surgery.

Of the 100 patients, follow-up X-rays showed that 53% had no sign of OA. Of the remaining patients, almost half ended up with some amount of degeneration. Mild degeneration was seen in 34%. Another 12% had moderate degeneration, and 1% had severe degenerative changes. Not everyone who had signs of OA felt pain or significant symptoms, however.

The X-rays showed a link between patellofemoral OA and a shortened patellar tendon. The worse the OA, the shorter the patellar tendon. The authors suggest the two may go hand-in-hand. There also tended to be a connection between patellofemoral OA and the spot where the tendon graft was placed. The incidence of OA was higher when the graft was placed slightly forward on the femur and further back on the tibia. 

It is impossible to tell from this study how much the original knee injury, the type of surgery, or immobilization after surgery affected the development of OA. It is possible that newer surgical techniques using the arthroscope could show a lower rate of post-surgical OA in the patellofemoral joint. Patients usually don’t immobilize their knees during rehabilitation anymore, either. This study can help give a baseline to see if newer techniques are any better at preventing the “seven-year hitch” of post-operative OA in patellofemoral joint.

Eye Love to Play Football

Adults are usually quick to screech advice when kids run with sticks or scissors. But it might be just as good advice for professional football players. Nineteen NFL football players were followed after fracturing the bones surrounding the eye. Most often a finger in the eye was the culprit, although less often the injury was caused by blunt trauma. It seems that offensive linemen needed to “watch out” more than any other position. Some injuries resulted in permanent vision problems, most commonly double vision. Coaches and players are more aware of the risk of injury to the eyes, and certain players are now wearing protective eye shields in the NFL.

Putting the Squeeze on Old Yeller’s Discs

It is commonly believed that heavy physical loads on the spine cause the discs between the vertebrae to degenerate. The authors of this article tested that theory. They used screws and coil springs to compress the discs of dogs for up to one year. Then the dogs’ spines were studied for signs of degeneration.

The X-ray results showed no visible signs of degeneration. Researchers noticed no disc bulging, disc space narrowing, or cracks in the spine. However, they did see some microscopic changes in the cells of the discs. According to the authors, these microscopic changes might be early indicators of degeneration, which “supports the commonly held belief that high compressive forces play a causative role in disc degeneration.”

A year is an ample time to see if compression really has an affect on the spinal discs. And even though there were no visible changes, the microscopic changes suggests that care should still be taken when it comes to heavy and repeated loads on the spine. So although these new findings don’t add support for the old theory about disc compression, the old theory shouldn’t be discarded on this evidence alone.

A+ Results Long after Rotator Cuff Repair

Doctors and researchers know a lot about the short-term benefits of repairing rotator cuff tears. But how do these repairs hold up over time?

The authors followed up on 105 surgeries done between 1975 and 1983. All the surgeries repaired a full-thickness rotator cuff tear. All the patients also had an acromioplasty, which involves removing a part of the acromion (top edge) of the shoulder blade. The authors found that the surgeries successfully eased pain and greatly improved shoulder range of motion and strength in most cases. Overall, about 80% of the shoulders had an outcome rated excellent or satisfactory an average of 13 years after surgery.

When the authors analyzed the patient information, they discovered that large tears had worse outcomes than medium or small tears.
Patients with small tears had 94% excellent or satisfactory results. Patients with medium tears had 85% excellent or satisfactory results. This compares to 74% of patients with large tears and only 27% of patients with massive tears. In general, older patients had larger tears. For some reason, women also had somewhat worse results than men overall.

The authors give rotator cuff surgery an “A” on the test of time. They suggest that new technology and surgical methods should focus on better repair of large rotator cuff tears.

Piecing Together the Disability Puzzle

“Low back pain remains a thorn in the side of modern medicine,” write the authors of this article. It’s no wonder. The causes of low back pain (LBP) can be difficult to diagnose, and LBP can be expensive and frustrating to treat. It also causes problems on the job with absenteeism, lost wages, and workers’ compensation costs.

Determining the level of disability caused by LBP is an ongoing problem for health care providers. Tests such as X-rays and MRI scans don’t always help doctors make a diagnosis. Research shows that the results of these tests can’t predict levels of pain or disability. As a result, much research has focused on finding reliable ways to measure the disability caused by LBP. The researchers of this study looked at spine degeneration shown on X-rays to see if it related to levels of pain or disability.

This study included 172 patients with LBP. They answered questions about their pain and ability to do certain tasks. Patients also reported if their back pain was caused by an injury. Patients then had X-rays of taken of their lower back.

The authors found that the patients who reported a past back injury tended to have more degeneration in the joints of their spine. However, no differences were found in disability or pain levels between patients who had an injury and those who hadn’t. There was also a weak link between how much pain a person had and the amount of degeneration seen on X-ray.

The authors conclude that much more research is needed to put together the pieces of the LBP disability puzzle. Researching disability is especially hard because there are often other factors involved. Consciously or unconsciously, patients commonly exaggerate their symptoms. In some cases, patients may want disability status in order to get time off work or to gain the upper hand in a lawsuit. The authors note that disability studies done in countries where lawsuits are common may influence research results.

The Older They Get, the More Comfortable the Couch

A lot of our lifestyle choices and habits are set when we are in our 20s: career paths, marriage and family, diet, exercise. It is common for physically active teenagers to become sedentary adults by age 30. Health professionals are constantly urging adults to get off the couch and get moving. If they knew when and why young adults stop exercising, health professionals could better target a solution.

Researchers in Australia looked at surveys of the physical activity of more than 7000 young adults. The subjects were divided into three age groups: 18 and 19, 20 to 24, and 25 to 29. The groups were rated according to vigorous exercise, moderate exercise, sufficient exercise for health benefits, and how much they walked.

The older the group, the less often they took part in all four categories of exercise. The results showed up to a 21% decrease in exercise from age 18 to age 21. Researchers also looked at the difference between exercise styles in men and women. For all age groups, men had higher rates of vigorous and moderate activity. However, the results suggest that men get more sedentary than women as they age. Women had much higher rates of walking than men–and the rates of walking dropped off less in the older groups of women.

A study done in the United States might show different results. Still, this type of knowledge is useful to doctors and other health professionals who want to help their younger patients find ways to keep exercising as they start their careers and families. Based on this evidence, doctors should encourage many young women to add some moderate-intensity workouts to the walking they already do. And men should be encouraged to find more moderate types of activities, such as walking and biking, as they move away from the high-intensity activities of their youth. The authors suggest that helping people develop healthy exercise habits in their youth might be more successful than trying to get middle-aged and older adults off the couch.

Nasal Dilators: The Sweet Smell of–Nothing

If you watch the Super Bowl or any other professional football game, you will see players wearing nasal dilators. Nasal dilators are the little strips that stick on the skin over the bridge of the nose. The idea is that they expand the nasal airways, making it easier to breathe. Nasal dilators are sold in drugstores as devices to decrease snoring. Football players and other athletes wear them with the goal of improving their athletic performance.

This study suggests that all nasal dilators really do is look sort of funny. Earlier research has shown that there is less resistance when breathing through the nose while wearing a nasal dilator. But improving athletic performance would require that they actually reduce the amount of work it takes to breathe. But no research has measured whether nasal dilators decrease the work of the breathing muscles–the muscles surrounding the lungs. Until now.

For this study, researchers tested 14 untrained young subjects as they rode an exercise bike. Each subject did two exercise tests. During one test subjects wore nasal dilators; during the other, they wore fake nasal dilators. The resistance on the bike was continuously increased until the subjects couldn’t keep going. The subjects swallowed a special type of balloon, which was placed just above the stomach. The balloon was attached to a machine that measured the efforts of the breathing muscles during exercise. The subjects’ air flow was also measured.

The results showed no real differences in the work of breathing or air flow during exercise. Based on this study, pro football players might as well take off their nasal dilators–or perhaps they could just use them as another spot to sell advertising.

Predicting the Future of Low Back Pain

Low back pain (LBP) is unpredictable. It can go away within a few weeks, or it can become an ongoing, lifelong problem. People with LBP (and their doctors) would love to have a crystal ball to show them what to expect for their back in the future.

These authors don’t supply a crystal ball. But they did look for ways to predict which patients with LBP will have long-term problems. They looked at records of more than 1200 patients with LBP to see if there were common factors in those whose pain became chronic. They interviewed patients six times over 22 months.

Patients answered questions about their pain levels, medical care, work status, and ability to do certain tasks. Patients who were still having symptoms after three months were considered to have chronic LBP. Patients who had symptoms throughout the 22 months were considered to have unremitting LBP.

The authors found that the 96 (7.7%) patients who had chronic LBP were more likely to be nonwhite and in a lower income bracket when they developed LBP. They were more disabled by their back pain and more likely to have pain that affected their legs (sciatica). The authors also found that the prognosis for these patients was poor. At 22 months, only 16% had no back symptoms. And 67% of patients still had symptoms that limited their ability to function normally.

Surprisingly, the authors found that patients with the worst LBP often got the least medical care. Of the 59 patients categorized with unremitting LBP, only 58% sought health care for their back problems from month three to month 22.

The authors conclude that, in their study, only two variables seemed to be of much use in predicting chronic LBP. Patients with less ability to function on their first doctor visit were especially likely to develop chronic LBP. And patients’ functional ability at the four-week mark was also strongly related to having future problems with chronic LBP. 

More research is needed to know exactly how these results can be used. And though it’s no crystal ball, this study can help doctors give their low-back patients an idea of what to expect in the future.

Making Low Back Pain Measure Up

Low back pain is one of the most common–and most costly–conditions in the U.S. Every year, about 2% of all workers suffer low back injuries on the job. Yet low back pain is one of the hardest conditions for doctors to measure and understand. Common tests, such as X-rays and MRI scans, can’t always pinpoint the underlying problem. They also don’t tell much about a patient’s level of disability.

To make matters worse, patients often don’t give a good idea of their symptoms in the doctor’s office. Consciously or unconsciously, they exaggerate their symptoms. This can happen when patients want disability status, or when they are nervous, scared of causing themselves pain, or depressed. But this makes it even harder for doctors to determine if the back condition is just painful, or if it is actually causing disability.

These researchers were looking for a way to measure spine function that isn’t consciously influenced by the patient. They studied test results of 91 patients with low back pain. Patients answered questions about their pain and their ability to do certain tasks. Patients then underwent standard tests of spine range of motion and strength. In addition, they also had a spinoscopic exam. A spinoscope measures coordination of the spine through movements of the individual vertebrae. Unlike range of motion or strength, it is nearly impossible for patients to influence these movements consciously.

Researchers then compared the results of the different kinds of tests. They found a weak relationship between disability, functional status showed by the tests, and patients’ reports of pain. Patients who rated their pain and disability highly tended to do somewhat worse on the standard range-of-motion and strength tests. However, there was a much smaller link between patients’ reports and the results of the spinoscopic examination.

The authors conclude that the weak link between the questionnaires and the functional tests means that doctors need to be careful in using patients’ self-reports to determine disability levels. They suggest that more complex measurements of spinal coordination, such as those from the spinoscope, could prove helpful in getting a better idea of patients’ disability levels.

The Dark Side of the Knee

The posterolateral (back and outside) corner of the knee has been called “the dark side of the knee.” Much less is known and understood about its complex structure than about the rest of the knee joint. This author sheds some light on injuries of the posterolateral part of the knee.

Posterolateral knee injuries don’t happen often. When they do occur, they can cause severe disability. Usually they happen along with damage to the central knee ligaments. In many cases, the injured ligaments are treated, but the injury to the posterolateral structures goes undiagnosed. When this happens, surgery for the central ligaments may eventually fail.

Posterolateral knee injuries are difficult for doctors to diagnose. There may be pain in the back and outside part of the knee. Damage to nerves is fairly common, so there may also be tingling or numbness in the leg. The author lists some ways for doctors to examine the knee and suggests imaging tests that can help identify damage to this part of the knee. Arthroscopy may be necessary for accurate diagnosis. This involves inserting a tiny TV camera into the joint.

Mild or moderate tears in the outer portion of the knee may heal without surgery. Complete tears usually require surgery. Surgery is more likely to be successful when it is done soon after a severe injury. Surgery is less successful when posterolateral problems develop over a long period of time. The author concludes that future research should focus on improving ways to repair the posterolateral corner of the knee, now that we are learning more about the knee’s “dark side.”

Putting the Kneecap in Its Place

When the kneecap is out of whack, doctors call the condition patellar malalignment. (The patella is the kneecap.) Patellar malalignment often goes undiagnosed. The author suggests that, when it is diagnosed, doctors are sometimes too quick to use surgery as the first treatment.

There are two kinds of symptoms related to patella problems, slipping and pain. Patients who feel the patella slip, or even dislocate, usually have mechanical problems with their knee. Patellar pain, on the other hand, isn’t fully understood by doctors. Many patients with patellar malalignment don’t feel any pain. Others do. Factors such as an injury or overuse seem to trigger the pain. Other disorders may cause the pain, such as nerve or blood vessel problems or inflammation of the patellar tendon. And some conditions can cause patellar pain even when the patella is correctly lined up.

The author discusses a number of ways to identify patellar malalignment. Foot problems, tightness of the muscles around the kneecap, and pain in certain knee positions can all suggest patellar malalignment. Most cases of patellar malalignment don’t require fancy testing or surgery. The pain usually goes away with conservative treatments including ice, rest, anti-inflammatory drugs, and physical therapy. Stretching and strengthening exercises have proven helpful as a way to keep the kneecap in better alignment. Knee braces or taping the kneecap may also help center the kneecap, easing pain. In some cases, abnormal foot positions cause the problems in the knee. Orthotics to better align the feet may help in these cases.

When their patients end up needing surgery, doctors have several ways to help. Most types of surgical procedures for this problem are used to improve the alignment of the patella.

Update on the Use of Arrows in Meniscus Surgery

In the past decade there have been many advances in the way surgeons repair the meniscus of the knee. New methods of surgery and new technology have helped make the surgery easier for patients and surgeons.

An absorbable implant is one type of technology that has become widely used in meniscus surgery. These biodegradable pieces can be placed through a tiny incision. A type of absorbable implant called an arrow is used to hold together healing tissues. It works sort of like a staple or a pin. The tissues heal together, and the implant slowly dissolves over a period of about three years.

These authors reported case studies of problems with arrows used in meniscus surgery. Four of 28 patients developed cysts over the arrows 10 to 12 weeks after surgery. The cysts all went away in 18 weeks by themselves. Another patient had the arrowheads break off the shaft of the arrow, causing small indentations in the cartilage on the surface of the thigh bone. The authors commented on other instances where the arrowheads had broken.

None of these patients had lasting difficulties. However, the authors suggest that more study is needed on the long-term effects of using arrows for repairing the knee meniscus. They were especially concerned that the broken arrowheads could indicate a design problem that may need to be corrected.