Capsulitis is inflammation of the joint capsule, the tough connective tissue sleeve that surrounds and stabilizes a joint. It can affect any joint in the body, but the two most common locations are the shoulder (where it’s known as adhesive capsulitis or frozen shoulder) and the base of the second toe. The inflammation typically starts with pain and progresses to stiffness and restricted movement as the capsule thickens and tightens around the joint.
How Capsulitis Develops
Every movable joint in your body is enclosed in a capsule made of ligaments and connective tissue. This capsule holds lubricating fluid inside the joint and keeps the bones properly aligned. When the capsule becomes inflamed, the process follows a fairly predictable pattern: inflammation comes first, causing pain and swelling, then scar-like tissue (fibrosis) gradually builds up within the capsule walls. Specialized cells called fibroblasts multiply and deposit excessive collagen, which thickens and shrinks the capsule. The result is a joint that hurts and progressively loses its range of motion.
Capsulitis in the Shoulder
Adhesive capsulitis of the shoulder, commonly called frozen shoulder, is the most well-known form. It typically unfolds in stages over many months. The first phase is dominated by pain, sometimes severe enough to disrupt sleep, with motion gradually becoming more limited. In the second phase, pain may ease somewhat but the shoulder becomes significantly stiffer. Reaching overhead, rotating your arm outward, or fastening a seatbelt can all become difficult. The final phase is a slow thaw, where range of motion gradually returns.
The entire cycle from onset to resolution typically takes 12 to 18 months with conservative treatment, though some cases drag on longer. Clinically, a diagnosis is made when you’ve lost more than 25% of your passive range of motion in at least two directions, combined with a 50% loss in rotation compared to your unaffected side. Imaging isn’t always necessary, but ultrasound or MRI can reveal telltale thickening of the capsule (greater than 4 mm in the lower portion of the shoulder capsule is a commonly used threshold).
Capsulitis in the Foot
The second most common site is the ball of the foot, specifically the joint at the base of the second toe. This form is sometimes called predislocation syndrome because, left untreated, it can progress until the toe drifts out of alignment. Capsulitis can also occur at the third or fourth toes, but the second toe bears the brunt in most cases.
Early symptoms include pain on the ball of the foot that feels like stepping on a marble or walking with a bunched-up sock. You may notice swelling around the base of the affected toe, pain when walking barefoot, and difficulty finding comfortable shoes. In advanced stages, the inflamed ligaments weaken enough that the toe becomes unstable, gradually drifting toward the big toe. The end stage is a “crossover toe” that sits on top of the big toe.
Because the pain is concentrated in the ball of the foot, capsulitis is often confused with Morton’s neuroma, a nerve condition that produces similar symptoms in the same area. The key difference is location: capsulitis pain centers directly at the base of the toe joint, while neuroma pain tends to radiate between the toes and may cause numbness or tingling.
Who Is Most at Risk
Diabetes is the strongest known risk factor for adhesive capsulitis of the shoulder. Up to 20% of people with diabetes develop frozen shoulder at some point, and some research has found rates as high as 67% in diabetic populations compared to roughly 9% in non-diabetics. The connection likely involves how chronically elevated blood sugar affects connective tissue, making it more prone to thickening and scarring.
Other conditions linked to shoulder capsulitis include thyroid disorders, autoimmune diseases, and cervical spine problems. Any period of prolonged shoulder immobilization, whether from a fracture, rotator cuff tear, or surgery, also raises the risk. For foot capsulitis, structural factors play a bigger role: a second toe that’s longer than the big toe, bunions that shift pressure distribution, and high arches all increase stress on the second toe joint. High heels and shoes with narrow toe boxes compound the problem.
Treatment for Shoulder Capsulitis
Most people with frozen shoulder recover with a combination of pain management and physical therapy, though patience is essential given the 12-to-18-month typical timeline. During the painful early phase, anti-inflammatory medications and gentle range-of-motion exercises form the foundation. Vigorous stretching at this stage can actually backfire by worsening inflammation and increasing pain.
Corticosteroid injections into the shoulder joint offer significant short-term relief. In studies comparing injections to physical therapy alone, 77% of patients treated with injections showed major improvement by seven weeks, compared to 46% with therapy alone. The benefit tends to level off by about six months, at which point outcomes are similar to those achieved with oral anti-inflammatory medications. Still, injections can serve as a valuable bridge, reducing pain enough to allow more effective physical therapy.
Once the intense pain subsides, structured rehabilitation becomes the priority. Guidelines recommend starting with 3 to 4 short sessions per day (10 to 15 minutes each) of assisted range-of-motion exercises, including forward elevation, rotation, and cross-body movements. Strengthening the muscles around the shoulder blade and rotator cuff comes next.
Cases that don’t respond to 6 to 9 months of conservative treatment may be candidates for surgical options, typically an arthroscopic capsular release (where the surgeon cuts through the thickened capsule to restore movement) or manipulation under anesthesia. Recovery from arthroscopic shoulder procedures generally involves wearing a sling for 1 to 6 weeks, returning to desk work in 2 to 3 weeks, and completing 4 to 6 months of rehabilitation. Physically demanding jobs usually require 3 to 4 months off.
Treatment for Foot Capsulitis
Treating capsulitis in the foot centers on reducing pressure on the affected joint before the ligaments stretch out permanently. Early intervention makes a meaningful difference because once the toe starts drifting, non-surgical options become less effective.
Footwear changes are the first line of defense. Shoes should have a wide toe box, a flat or low heel, and a thick sole that isn’t overly flexible. A rocker-bottom sole can help by reducing the bending force on the ball of the foot during walking. Metatarsal pads placed just behind the metatarsal heads (not directly under them) spread pressure across a wider area and take load off the inflamed joint. Custom orthotics can address underlying structural issues like high arches or abnormal foot alignment, and some designs include a small cup beneath the painful metatarsal head for targeted relief.
Taping the affected toe to hold it in a corrected position, icing the ball of the foot, and using anti-inflammatory medications all help manage symptoms during flare-ups. If these measures fail and the toe continues to destabilize, surgical repair of the damaged ligaments or realignment of the toe may be necessary.