This article originally appeared in the September 2024 issue of Parachutist, the official publication of the U.S. Parachute Association. It is reprinted here with permission. Written by Dr. Laura Galdamez.
There are three common types of knee injuries: fractures, dislocations and soft-tissue injuries. According to studies of military skydivers, soft-tissue injuries (strains, sprains and over-stretching) make up the majority, while roughly 15% involved an actual fracture or dislocation. Although the rate of leg injury was greater for jumpers over 30 years old, knee injuries occurred most often in jumpers aged 19-25 years old.
Not surprisingly, the vast majority of these occur in landing incidents—specifically related to the way in which the legs are positioned when touching down, which can lead to stress on different areas of the knee. Landing in a leg-wide stance leads to pressure on the inside knee ligament and can lead to medial collateral ligament (MCL) injuries, while landing with one leg reaching down can lead to hyperextension, outward pressure or twisting injuries to the knee ... can you say anterior cruciate ligament (ACL) tear? Landing with the balls of the feet extended can cause a sudden collapse of the feet when the jumper’s full weight hits, resulting in a fall forward onto the knees and over-flexing or bending of the knee.
Here’s what you knee’d to know about the three types of knee injuries, as well as how to treat, manage and prevent them!
Fractures
Three bones break most often with with knee injuries: the femur (largest upper leg bone), the tibia (shin bone) or the patella (kneecap). A femur fracture will not be subtle. These are quite obvious when the leg is angled in the wrong direction and pain is severe. You won’t be walking away from that fall.
Figure 1: Tibia Fracture
The tibia can break in a variety of ways. Sometimes it looks like a firecracker exploded and shattered the bone (see Figure 1). Again, you won’t be walking away from this one. However, it may be a subtle bone-compression fracture at the very top near the knee. This type of compression fracture, called a tibial plateau fracture (see Figure 2), happens most commonly from a fall or direct impact. Usually, the knee will be swollen and fairly tender, accompanied by difficulty bearing weight. Many tough sons-of-guns will keep walking on this fracture, doctors commonly miss it because the findings on X-ray are subtle. It is important to know whether you have this compression fracture, as having an associated ligament injury (i.e. ACL or posterior cruciate ligament, aka PCL) is common because these ligaments attach to the fractured bone.
Figure 2: Tibial Plateau Fracture
The patella is connected on top to the quad muscles via the quadriceps tendon and to the tibia on the bottom via the patella tendon. These tendons and muscles help to extend the knee joint. However, if the knee is forcefully bent (such as during a fall) when the quads are contracted, this can literally break and pull the kneecap bone apart (see Figure 3). A direct impact, such as falling directly onto the knees, can also fracture the kneecap. This injury is most common in 20-to 50-year-olds and occurs more frequently in males.
Figure 3: Patella Fracture (front and side views)
Dislocations
A dislocated kneecap is one injury that looks far worse than it actually is. This can happen from a direct blow to the knee; forcefully pushing the kneecap to the side; or from a twisting motion of the leg that causes the femur to rotate inward while the knee stays stationary, causing the kneecap to slide out of place. You may experience this as a “popping” sensation at the knee, and your first thought when you look will be, “My knee is totally jacked up!!” Luckily the fix is pretty easy, and it is actually one of the less severe injuries despite its startling appearance.
Figure 4: Knee Dislocation
The more severe trauma is a true knee dislocation. This is where the femur completely dislocates and moves off the tibia, out of the knee joint (see Figure 4). This requires a very high-speed impact, because it involves stretching and/or tearing of at least two (but usually more) of the knee ligaments. Usually both ACL and PCL are completely torn, and 50% of injured people tear the side ligaments, as well. Limb-threatening arterial injuries occur in one third of people who dislocate their knees, and a delay in repairing this artery greater than 8 hours post-injury results in an alarming 86% rate for leg amputation. Additional nerve injuries and fractures are common, as well. When there’s a knee at the drop zone the size of a Texas grapefruit, it’s time for a trip to the E.R.!
Soft-Tissue Injuries
Now is a good time to double check those tendons that connect the knee cap to the quad muscles and shin bone. Both of those can be either partially or fully torn, which usually occurs from a fall onto a flexed knee. These are rare injuries, and particularly the quad-tendon rupture tends to occur only if there is a predisposing factor such as older age, prolonged steroid use or use of specific antibiotics that weaken tendons (e.g., ciprofloxacin, levofloxacin). The patella tendon ruptures more in younger males with underlying medical issues, but even then, it can take a force of 17.5 times the person’s body weight to tear that tendon! So how can a skydiver know that it’s torn? The kneecap will be riding higher up the leg than normal (compare it to the other knee to be sure) and there will be difficulty straightening the leg.
Most people are more familiar with a few other soft-tissue injuries. The ACL is the most common ligament that needs surgery, and females are four times more likely to tear their ACLs compared to their male counterparts (see Figure 5). The injury is usually sustained during a twisting maneuver on a planted foot, and the classic popping sensation is followed by the knee giving way and a significant amount of joint swelling. The PCL can also be torn, but usually requires a higher mechanism of force and is caused by hyperextension. The MCL is the most common ligament injury of the knee and occurs from a direct blow to the outside of the knee. There is a similar popping sensation, but the resulting pain is focused on the inside of the knee. The meniscus can also tear, resulting in pain inside the joint and sometimes a clicking sensation with certain movements.
Figure 5: ACL and Meniscus Injury (Image: Creative Commons)
“But hey, Doc, I haven’t done anything to my knee and it still hurts!”
Well, “anything” means something much different for a person who consistently lands their body after a 14,000-foot fall from an airplane. One common issue that can occur with overuse of the knee (such as a day’s worth of landings) is bursitis. Our kneecaps essentially have a water-balloon-like structure (the bursa) that helps to cushion from direct trauma or prolonged pressure. When the trauma or pressure are too much (like kneeling at the door repeatedly on training jumps or during yet another go-around), it can cause irritation and inflammation of the bursa. Before you know it, it can look like you have a little red, pissed-off golfball sitting on your kneecap that screams at you if you even think of putting pressure on it. Overuse can also cause the tendons to become inflamed and irritated, resulting in tendinitis. The knee may look completely normal, but the inflamed tendons will cause pain with any movement of the knee joint.
When should I seek medical care?
Rule #1: If you can’t walk on it, see a medical professional. Outside of that simple rule, other indicators that signal a need to visit the emergency department include an inability to lift the knee straight, inability to flex the knee to 90 degrees, or tenderness specifically over the kneecap or the outside of the lower aspect of the knee joint. Sometimes tearing the ligaments can be far less painful than one would think, but one indication of this injury is significant swelling of the entire knee. If that happens and the initial X-rays are negative, consider getting an MRI through either a primary care doctor or an orthopedic surgeon.
Rule #2: Do not jump on an unstable knee! Pain is one thing, but instability can lead to further, more serious injuries.
What can I do in the field to help myself or a friend?
This is pretty straightforward (with one exception). If the knee is already straight, immobilize the joint using something stiff to prevent bending and help keep all weight off the leg before a visit to an urgent-care or emergency department. Use a rigid brace, SAM splints, thick cardboard, broomsticks with duct tape, ace wraps or fabric strips to secure a temporary splint around the injured leg at several points (see Figure 6).
Figure 6: Temporary Splint
The one exception is if you notice the knee is bent and the kneecap is dislocated to the side. It is best to wait for paramedics to provide medications for the pain. But what if you are in the middle of nowhere and help is hours away, if it’s coming at all? In that case, the best strategy is to gently straighten the leg and provide very gentle pressure on the outside of the knee cap until it slides back into place. It generally takes very little effort to relocate, and can provide a lot of pain relief, but the process of doing it can be fairly uncomfortable and scary for the victim. It’s important to keep them calm, using whatever distractions might be available.
How do I manage these injuries?
For all patients sent home with a soft-tissue knee injury, the three best things to do are to wrap tightly with an ace bandage to prevent/reduce swelling, elevate the knee above the level of the heart and apply an ice pack for 20-30 minutes every two to three hours.
Those with kneecap fractures are sent home in a straight knee immobilizer . Hairline fractures where the knee can still be extended likely won’t require surgery. But if the knee cannot be extended or if the broken halves have pulled apart or left a piece of bone in the joint, surgery (with tension bands, wires and screws) will likely be necessary. When a kneecap is shattered, there is a good chance that part or all of it will need to be removed.
Figure 7: Knee Immobilizer
Skydivers with a broken tibia (shinbone) or with hairline or compression fractures are typically sent home in a knee immobilizer or a splint from the back of the thigh to the toes, with outpatient orthopedic follow-up. If the joint is not involved in these hairline breaks, surgery can be avoided with 8-12 weeks of a long leg cast but healing can take up to 20 weeks. But, as is always the case, the necessity of surgery is determined by the significance of the injury.
Kneecap dislocations are quickly reduced in the emergency department. Those with first-time dislocations should start early range-of-motion exercises and return to normal activity. Recurrent dislocations may require surgical management, as it can help reduce the rate of dislocations, but at the end of the day, conservative management (no surgery) seems to work just as well as surgery.
Knee dislocations are a different story. These will still be reduced in the emergency department, but are much more difficult. They can be very unstable since the injury itself includes tearing of two or more of the stabilizing ligaments of the knee. If the knee is stable after reduction, several weeks in a knee immobilizer (to allow swelling to reduce), followed by surgery, may be necessary. If the joint is especially unstable after reduction, there may be immediate surgery. That also may be case if there is damage to the artery or the emergency department can’t reduce the dislocation..
Image: Lonnie Kirk
Aren’t these terrible visuals fun? Moving on to other soft-tissue injuries, what if the tendons that connect the kneecap to the leg are torn? Well, if there is a tear of the bottom tendon (patella tendon), the doctor should require a knee immobilizer (see Figure 7) or long leg splint, with orders to remain on crutches until surgery, about two weeks later. Recovery is around 16 weeks. For the top tendon (quadriceps tendon), an incomplete rupture requires six weeks in a cast and then physical therapy to recover range of motion and strength. A full rupture requires early surgery (within two to three days) to prevent the tendon from shrinking back. Then it’s the immobilizer for four to six weeks.
Next up are the very common ligament injuries (including the ACL)—basically, when the knee swells up significantly, feels super unstable and nothing’s broken. An MRI is the only way to diagnose, so if a skydiver has plans to follow up with an orthopedist, it’s smart to get an MRI first to verify the injury. ACL tears usually require surgery, whereas PCL, MCL and LCL injuries usually don’t. These non-operative tears are treated with a brace or cast, and some hardcore physical therapy. The exception would be if the knee is unstable, multiple ligaments are injured or if there is an avulsion/chip fracture associated with the tear. While the emergency department may offer a knee immobilizer, a hinged knee brace is both more comfortable and preferred by the orthopedic surgery community. Find one on Amazon and order immediately!
Lastly, what about bursitis—the angry, painful golf ball over the knee cap? For that sucker, think ibuprofen (Motrin, Advil), rest, ice, compression with an ace wrap and avoiding triggers, such as kneeling on it. Can’t avoid it? (Yep, typical skydiver.) Well, at least use a protective cushion with some stellar knee pads. It may be helpful and necessary to have the bursa drained, get a steroid shot directly into it or even have the fluid sac removed in extreme cases.
What if it’s the tendon that’s pissed off? Tendinitis is the cause of quite a bit of knee pain out there. Typically, this requires rest (no, not immobilization, just decrease of activity), ice at least three to four times daily (20 minutes each), good stretching of the quads, hamstrings and calves, and additional strength exercises to help build resilience as the symptoms improve. Steroid injections into the tendon are dangerous and can increase the risk of a tendon rupture.
I don’t want this junk! How do I prevent knee injuries?
The best thing to do is to strengthen the muscles that stabilize the knee. Those muscle groups are primarily the quads and hamstrings. There are plenty of exercises to build strength. Lateral walks involve placing a tension band around the ankles and walking sideways four to five steps back and forth. Lunges involve stretching one leg in front and squatting down so the front knee bends to 90 degrees and the back knee nearly touches the ground. Squats or wall squats (holding a squat with the back against a wall) are also great for the quad and core muscles. There are other exercises such as straight leg raises, step-ups, single leg dips, etc. Here is a great resource for knee-specific exercises: orthoinfo.aaos.org/en/staying-healthy/knee-exercises/.
The majority of skydivers stretch far less than they should, adding this simple act into the daily routine can make a huge difference. For knees specifically, stretch the quads with a standing stretch, raising each leg one at a time, pulling up from behind. For the hamstrings, stretch forward while standing, trying to touch toes with legs straight, or by lying down and using the hands behind the thigh to pull the straight leg up toward the head. Calf stretches are important too!
What about using a brace or an ace wrap? While they haven’t been proven to prevent injuries, both braces and ace wraps can help increase joint stability and prevent side to side movement. When both were tried in comparison, most skydivers reported that the semi-rigid knee brace felt more protective, but the elastic wrap was more comfortable.
Well, that about does it for knees and potential skydiving injuries. Keep an eye out for future articles on the hips, shoulders, elbows and beyond!
About the Author
Laura Galdamez, M.D., D-41824, began skydiving in early 2020. She works as an emergency medicine physician in Houston, Texas; is a Fellow of the Academy of Wilderness Medicine; and worked on the medical team for StratEx high-altitude balloon mission. She competes on several formation skydiving teams based at Skydive Arizona in Eloy.
Article written by Dr. Laura Galdamez.
This article originally appeared in the September 2024 issue of Parachutist, the official publication of the U.S. Parachute Association. It is reprinted here with permission.
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[Photo sources: Parachutist, Laura Galdamez, Creative Commons, Lonnie Kirk]