Bow legs in adults show up on my standing X-rays almost every clinic day, and most people have no idea the shape of their leg matters. Some have been bowlegged since childhood; others notice their knees drifting apart as the inner knee starts to ache.
After more than twenty years of practice and more than 700 joint replacements a year, here’s what I tell my patients: the shape of your leg and the health of your knee are tied together. Let’s walk through what causes bowing, when it matters, and what actually fixes it.
What are bow legs in adults?
Bow legs in adults means your knees stay apart when you stand with your feet and ankles together. The medical name is genu varum. “Varus” means the lower leg angles inward below the knee, so the leg curves outward like an archer’s bow.
In young children, bowing is a normal stage that usually corrects by age 3 or 4. Adult bones have finished growing, so adult bowing will not correct on its own; with arthritis, it slowly gets worse.
Some bowing is simply how you’re built, called constitutional varus. In a study of healthy adults in their twenties, about one in three men and one in six women had a natural bow of 3 degrees or more.
Straight, bowed, and knock-knee alignment. In bow legs, the weight line passes inside the knee.What causes bow legs in adults?
The most common cause in adults is osteoarthritis on the inner side of the knee. The other main causes are bowing left over from childhood, an old fracture that healed out of line, soft bones from low vitamin D, and loose or injured ligaments.
1. Knee arthritis: the most common cause of bow legs in adults
The inner side of the knee (the medial compartment) carries most of your weight when you walk. As its cartilage wears thin, that side loses height and the leg tips into a bow. You can see how that looks in my guide to knee arthritis on X-ray.
2. Bowing left over from childhood
Childhood causes such as Blount’s disease (a growth plate problem at the top of the shinbone) and rickets can leave bowing that never fully straightens. The American Academy of Orthopaedic Surgeons explains how bowing is treated in children.
3. An old fracture that healed out of line
A break near the knee can heal with a slight angle. Even a few degrees of tilt changes how weight passes through the joint for decades.
4. Soft bones from low vitamin D
Osteomalacia, the adult version of rickets, softens bone so the legs can slowly bend. A simple blood test checks for it.
5. Loose or injured ligaments
If the ligaments on the outer knee are torn or stretched, the knee can shift outward with each step, so the bow looks worse when you walk.
What symptoms do bowed legs cause?
Many adults with mild bowing have no symptoms at all. When symptoms do appear, the most common one is an ache on the inner side of the knee that gets worse with walking, stairs, or long days on your feet.
Other signs I look for include:
- A visible gap between the knees that seems wider than it used to be
- A sideways lurch of the knee with each step (surgeons call this a varus thrust)
- Shoes that wear down faster on the outer edge
- Bowing in one leg that is clearly worse than the other
Do bow legs cause knee arthritis?
Bowing does not guarantee arthritis, but it can make existing arthritis get worse faster. It works like a vicious cycle: bowing pushes more of your weight onto the inner knee, that cartilage wears faster, and the worn side collapses into more bowing.
A well-known study followed 237 people with knee arthritis for 18 months. Those with bowed knees were about four times more likely to see the inner side of the knee get worse.
That’s why I never dismiss bowing once you have knee pain. The alignment is part of the problem, and it shapes which treatments make sense.
How do doctors diagnose bowed legs?
A standing X-ray is the key test. A full-length image from hip to ankle lets me measure your alignment in degrees and see exactly where the bow comes from: the thighbone, the shinbone, or the worn joint itself.
In the exam room, I watch you walk, check your ligaments, and gently try to straighten the knee. A bow that corrects with gentle pressure (a flexible deformity) opens up different options than a stiff one. Here is how to read a knee X-ray.
A standing X-ray shows where the bow comes from and how much joint space remains.Can bow legs be corrected in adults without surgery?
No. Once you stop growing, exercise, braces, and shoe inserts cannot straighten the bone. What they can do is take pressure off the inner knee, ease pain, and help you stay active longer.
What nonsurgical treatment helps bowed legs?
- Hip strengthening. In one study, people with stronger hip muscle action while walking were about half as likely to see inner-knee arthritis worsen.
- Weight loss. Each pound you lose takes about four pounds of load off the knee with every step.
- An unloader brace. It shifts weight toward the healthier outer knee.
- A cane in the opposite hand. Simple, and it takes real load off the knee.
- Low-impact activity. Cycling and swimming are easier on a bowed knee than running.
- Injections. A cortisone shot can calm a flare while you build strength.
We build these into a plan through our nonsurgical joint pain treatment program.
Do bow leg exercises or insoles straighten the legs?
No. Stretching videos can build strength, but they cannot reshape adult bone. And a review of 12 trials found wedge insoles relieved pain no better than a plain, flat insole.
What surgery corrects bow legs in adults?
The three main options are a high tibial osteotomy, a partial knee replacement, and a total knee replacement. The right one depends on your age, how much arthritis you have, and whether the bow comes from the bone or from the worn joint.
| Option | Best fit | Straightens the leg? | Typical recovery |
|---|---|---|---|
| Nonsurgical care | Mild bowing, mild to moderate pain | No | Ongoing; no downtime |
| High tibial osteotomy | Younger, active adults with wear mostly on the inner side | Yes, by reshaping the shinbone | Several months while the bone heals |
| Partial knee replacement | Arthritis in one compartment, flexible bow | Partly, by restoring lost joint height | Often the fastest of the surgical options |
| Total knee replacement | Advanced arthritis or a stiff, severe bow | Yes, as part of the operation | Most daily activities in about 6 to 12 weeks |
High tibial osteotomy
The surgeon cuts the shinbone below the knee, opens or closes a small wedge, and holds it with a plate. This shifts weight to the healthy outer side and saves your own knee. It suits younger, active people, and if that’s you, we’ll connect you with the right specialist.
Partial knee replacement
When arthritis is limited to the inner compartment and the bow corrects with gentle pressure, a partial knee replacement resurfaces only the worn side. A severe or stiff bow usually rules it out.
Total knee replacement
For advanced arthritis, a total knee replacement resurfaces the whole joint and corrects the bow as part of the operation. I plan many of these with the Mako® robotic system, which maps your knee in 3D so I can balance the ligaments before the first cut. I am a paid consultant for Stryker, which makes Mako.
I don’t always make the leg perfectly straight. If you’ve been slightly bowed your whole life, keeping a little of that shape can help the knee feel like yours; see personalized knee replacement.
When should you see an orthopaedic surgeon about bowed legs?
See an orthopaedic surgeon if your bowing is getting worse, is clearly worse on one side, or comes with knee pain that limits walking, sleep, or daily life. Mild, lifelong bowing with no pain does not need treatment.
Book a visit sooner if you notice:
- A bow that has changed noticeably in the past year or two
- A knee that buckles or suddenly gives way
- Inner knee pain that no longer settles with rest
I see patients from Franklin, Nashville, Columbia, and across Middle Tennessee at the Bone and Joint Institute of Tennessee, 3000 Edward Curd Lane, Franklin, TN 37067. Davidson County patients can visit my knee replacement page for Nashville patients.
Schedule a consultation with Dr. Calendine or call (615) 791-2630.
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Medical disclaimer: This article is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified orthopaedic surgeon or healthcare provider about your specific condition. Individual results vary.
References
- Sharma L, Song J, Felson DT, et al. The role of knee alignment in disease progression and functional decline in knee osteoarthritis. JAMA. 2001;286(2):188-195. doi:10.1001/jama.286.2.188
- Bellemans J, Colyn W, Vandenneucker H, Victor J. Is neutral mechanical alignment normal for all patients? The concept of constitutional varus. Clin Orthop Relat Res. 2012;470(1):45-53. doi:10.1007/s11999-011-1936-5
- Chang A, Hayes K, Dunlop D, et al. Hip abduction moment and protection against medial tibiofemoral osteoarthritis progression. Arthritis Rheum. 2005;52(11):3515-3519. doi:10.1002/art.21406
- Messier SP, Gutekunst DJ, Davis C, DeVita P. Weight loss reduces knee-joint loads in overweight and obese older adults with knee osteoarthritis. Arthritis Rheum. 2005;52(7):2026-2032. doi:10.1002/art.21139
- Parkes MJ, Maricar N, Lunt M, et al. Lateral wedge insoles as a conservative treatment for pain in patients with medial knee osteoarthritis: a meta-analysis. JAMA. 2013;310(7):722-730. doi:10.1001/jama.2013.243229
