Your questions, answered.

Impingement means the space between the bony tip of the shoulder blade (the acromion) and the rotator cuff tendons narrows as you raise your arm, so the bone can irritate the tendon and the bursa under it. It causes pain at the front or side of the shoulder, pain lifting the arm overhead, and often night pain. It is common in swimmers, throwers and racquet-sport athletes, and in people who work with their arms overhead. AAOS OrthoInfo

Treatment starts without surgery: activity changes, anti-inflammatory medicine, physical therapy to restore motion and then strengthen the cuff, and sometimes a steroid injection. The evidence for surgery is limited. In the UK CSAW trial of 313 adults, decompression surgery was only slightly better than no treatment at 6 months, and the difference was below the threshold the researchers considered meaningful. CSAW summary (NIHR)

Younger patients mostly have injury and overuse problems. Overhead athletes and workers develop impingement and tendon irritation. A fall or collision can dislocate the shoulder, and a shoulder that has dislocated once is prone to dislocating again; ligaments or the labrum (the rim of the socket) may be torn. Rotator cuff tears in young adults are more often caused by trauma than by wear. OrthoInfo: instability · OrthoInfo: rotator cuff tears

Treatment usually begins with activity changes, anti-inflammatory medicine and physical therapy. Surgery to repair or tighten the ligaments is recommended for repeated dislocations or when therapy does not control the instability, and it can often be done arthroscopically.

Wear and tear becomes the main cause. Rotator cuff tears become more common with age: in a screening study of 683 people in Japan (average age 58), about 21% of shoulders had a full-thickness cuff tear, and the rate rose with age. Many tears cause no symptoms, but people with shoulder pain were more likely to have one (36%) than people without pain (17%). Yamamoto et al., J Shoulder Elbow Surg 2010

Osteoarthritis of the shoulder and AC joints, biceps tendon irritation, and arthritis from a long-standing cuff tear (cuff tear arthropathy) also become more common after about age 50. Most can be treated with exercise, medicine and injections first; shoulder replacement is for advanced arthritis. OrthoInfo: arthritis of the shoulder

The rotator cuff is four tendons that hold the ball of the shoulder in its socket and lift and rotate the arm. A tear means one or more of them has partly or fully come off the upper arm bone; the supraspinatus tendon is the most often involved. Tears can happen suddenly (a fall, or lifting something heavy) or wear gradually with age and overuse. Typical symptoms are pain at rest and at night, pain lifting the arm, and weakness. OrthoInfo: rotator cuff tears

About 80 to 85% of patients improve with non-surgical care (rest, therapy, medicine, sometimes an injection), according to AAOS. Surgery is considered for continued pain after 6 to 12 months, a large tear, significant weakness, or a recent injury in an active person. In a Finnish randomized trial of 180 shoulders with non-traumatic tears, adding surgery did not improve pain or function at 2 years compared with physical therapy alone, though surgically repaired tendons looked better on MRI. Kukkonen et al., J Bone Joint Surg Am 2015 · Rotator cuff tear page

It is irritation or swelling of the upper (long-head) biceps tendon where it enters the shoulder. It usually comes from age-related wear made worse by overhead activity, and often appears together with rotator cuff problems, arthritis or labral tears. It causes pain at the front of the shoulder, pain reaching behind you, and sometimes an ache down the upper arm or a snapping feeling. OrthoInfo: biceps tendinitis

Most people improve with rest, ice, anti-inflammatory medicine, therapy and sometimes an ultrasound-guided injection. Surgery, usually arthroscopic, is considered if symptoms persist or return. The tendon is either released (tenotomy, which can leave a "Popeye" bulge) or reattached to the arm bone (tenodesis).

The AC joint is where the collarbone meets the tip of the shoulder blade, at the top of the shoulder. Cartilage wear here is the most common disorder of this joint and often causes pain on top of the shoulder, especially when reaching across the body or lifting overhead. Menge et al., Southern Medical Journal · OrthoInfo

Treatment begins with anti-inflammatory medicine, therapy and sometimes a corticosteroid injection. If pain continues, the usual operation is distal clavicle resection, removing a small piece of the end of the collarbone so the bones no longer rub; it can be done arthroscopically.

In the main shoulder joint (glenohumeral), the smooth cartilage on the ball and socket wears away until bone rubs on bone. Besides ordinary wear (osteoarthritis), causes include rheumatoid arthritis, a past fracture or dislocation, a long-standing large cuff tear, and loss of blood supply to the bone. It causes aching, grinding, stiffness and night pain. OrthoInfo: arthritis of the shoulder · UW Orthopaedics (Matsen)

Treatment starts with activity changes, gentle motion exercises, anti-inflammatory medicine and sometimes injections, which often give only temporary relief. Arthroscopic cleaning is mainly for mild arthritis. When pain and loss of function are significant despite this, shoulder replacement (anatomic or reverse) is the option that reliably relieves pain.

An anatomic replacement copies normal anatomy: a metal ball on the arm bone and a plastic socket on the shoulder blade. It depends on a working rotator cuff. A reverse replacement flips the parts, putting the ball on the socket side and the cup on the arm bone, so the deltoid muscle can lift the arm when the cuff is torn or worn out. OrthoInfo: arthritis of the shoulder

When the rotator cuff is intact and arthritis is the problem, either type can work. The right choice depends on the health of your cuff, your bone quality, your age and your goals, and Dr. Stepanyan will talk through which fits you.

A frozen shoulder (adhesive capsulitis) is a stiff, painful shoulder in which motion is lost in every direction, not just one. In the study below it was defined as more than 50% loss of motion in all directions for at least 3 months. It usually has no clear cause, and it tends to run its course over many months rather than years.

A Dutch study of 77 patients compared "supervised neglect" (an explanation of the natural course, gentle pendulum and active exercises kept within the pain limit, and carrying on with normal activities) with intensive physical therapy that included passive stretching and manipulation. After 2 years, 89% of the gentle group had a normal or near-normal, pain-free shoulder, against 63% of the stretching group, and the gentle group got there sooner (64% within 12 months). The authors suggest that forceful stretching during the painful, inflamed early phase may slow recovery. Their patients took about 15 months on average to recover. Diercks and Stevens, J Shoulder Elbow Surg 2004

Limits of the evidence: this was a small study that compared two groups treated in successive years rather than a true randomized trial, and diabetic patients were excluded. Injections, manipulation under anesthesia and arthroscopic release are options for stiffness that does not improve.

Not necessarily. In a randomized trial at two university centers, 89 patients who had a reverse shoulder replacement were assigned either to supervised physical therapy (twice a week at first) or to a home exercise program, which was a one-page handout and a rope pulley. After 1 year there was no significant difference in range of motion, strength-related scores, pain, satisfaction or complications (13% with home exercises, 17% with therapy). One in five patients in the home group switched to therapy, usually because their surgeon thought they were recovering slowly. The authors concluded that supervised therapy may not be needed for every patient. Chalmers et al., J Shoulder Elbow Surg 2023

Limits of the evidence: the trial studied reverse replacement only and followed patients for one year. Everyone wore a sling for 2 weeks with elbow, wrist and hand motion only, and routine follow-up was with the surgeon.

Not always, but for young, active patients the risk of it happening again is high. In a Scottish randomized, double-blinded trial, 88 patients aged 35 or younger who dislocated a shoulder for the first time had either arthroscopic Bankart repair (reattaching the torn labrum) or an arthroscopic washout without repair. After an average of 14 years, the shoulder had dislocated again in 12% of the repair group and 47% of the washout group, and any instability (including partial slips) occurred in 21% versus 72%. Further surgery was needed in 9% versus 28%. The authors argue that washout alone only delays recurrence. Yapp et al., J Bone Joint Surg Am 2020

Patients whose shoulders stayed stable did well whichever treatment they had. The trial compared two operations, not surgery against therapy alone, although the paper cites earlier randomized trials in which surgery cut recurrence compared with non-surgical care (for example 9% versus 62% at 10 years in one trial it cites). Most patients were young men (60 of 65), so the results apply best to that group. Older patients, and patients with bone loss on the socket or a large humeral head defect, need individual advice.

An AC separation is an injury to the ligaments that hold the collarbone to the tip of the shoulder blade, usually from a fall onto the shoulder. In the more severe grades (III to V) the collarbone sits higher, which makes a visible bump. A Canadian multicenter randomized trial of 83 patients aged 16 to 60 compared surgery with a hook plate against a sling and rehabilitation. The non-surgical group did better early: disability scores were better at 6 weeks and 3 months, and 76% were back at work at 3 months versus 43% after surgery. From 6 months on the groups were the same, and by 2 years both had good to excellent results. Surgery gave a better X-ray alignment, but it led to more complications (including plate loosening and erosion of the acromion) and more second operations, since the plate is usually removed. Source: Canadian Orthopaedic Trauma Society, J Orthop Trauma 2015;29:479-487.

The cost of not operating is the bump: at 2 years, 5 of 23 non-surgical patients were unhappy with how the shoulder looked, versus 1 of 25 after surgery. Limits: the trial tested one older fixation method (a hook plate); other techniques, such as ligament reconstruction, were not tested.

Knee pain has many causes, and they fall into three groups. Injuries include ligament tears such as the ACL, meniscus tears, fractures, and tendon irritation such as patellar tendinitis. Mechanical problems include a loose piece of bone or cartilage, iliotibial band syndrome, and a dislocated kneecap. Arthritis, most often osteoarthritis but also rheumatoid arthritis, gout and infection, is the other major group. Pain from the hip or foot can also change how you walk and load the knee. Mayo Clinic: knee pain

A sudden twisting injury with a pop and swelling points toward a ligament or meniscus tear. Pain that builds slowly, is stiff in the morning, or hurts on stairs and after sitting points toward arthritis or kneecap problems.

The work-up starts with your story: when it began, what you were doing, where it hurts, and whether the knee swells, locks, catches or gives way. Then comes an exam that compares both knees, checking swelling, motion, alignment, tenderness along the joint line, and ligament and meniscus tests. Many ACL tears and meniscus tears can be diagnosed from the history and exam alone. OrthoInfo: ACL · OrthoInfo: meniscus tears

X-rays come first for chronic knee pain; they show arthritis, alignment and fractures. MRI is added when a soft-tissue problem is suspected. Blood tests or joint fluid testing are used when infection, gout or inflammatory arthritis is possible.

Usually yes, because they answer different questions. X-rays show bone, joint-space narrowing and alignment, and are the recommended first image for chronic knee pain. MRI shows cartilage, meniscus, ligaments and tendons, but X-rays do not show meniscus or ACL damage and MRI does not replace them. The American College of Radiology rates X-rays as the usual first test, and MRI as appropriate afterward when a tendon, meniscus or ligament problem is suspected. ACR Appropriateness Criteria: Chronic Knee Pain (2026)

Where the pain is helps point to the cause. Pain in the groin, sometimes spreading to the buttock or knee, is the classic sign of arthritis of the hip joint itself, along with stiffness, a limp and pain that is worse after sitting. OrthoInfo: hip osteoarthritis Pain on the outer side of the hip, which hurts when lying on that side, is commonly from the tendons attached to the bony point of the hip (gluteal tendinopathy or tear). A randomized trial in the BMJ compared education plus exercise, a steroid injection and watchful waiting for this problem. Mellor et al., BMJ 2018 · Gluteal tendon page

Hip pain can also come from the lower back or from labral tears, and some hip pain is felt in the knee, which is one reason an exam and an X-ray of the hip are part of the work-up for knee pain without a clear cause.

The menisci are two C-shaped pieces of cartilage that cushion the knee and help keep it stable. Tears happen with twisting injuries in sports or, in older knees, with a simple awkward movement such as getting up from a chair. Symptoms include pain, swelling over a day or two, catching or locking, and a sense of the knee giving way. MRI is the preferred test; X-rays are used to rule out arthritis. OrthoInfo: meniscus tears

Not every tear needs surgery. The outer third of the meniscus has a blood supply and can be repaired, while the inner two thirds generally cannot heal and is trimmed if it causes symptoms. In a Finnish trial of degenerative tears, arthroscopic trimming was no better than sham surgery at 12 months. Sihvonen et al., N Engl J Med 2013 · Meniscus tear page

The anterior cruciate ligament runs through the center of the knee and keeps the shin bone from sliding forward and the knee from twisting. It usually tears in a sudden stop, pivot, awkward landing or collision, often with a pop followed by swelling within 24 hours and a knee that feels unstable. The diagnosis can usually be made on exam; MRI confirms it and looks for meniscus damage. A torn ACL does not heal on its own. OrthoInfo: ACL injuries

Surgery (reconstruction with a tendon graft) is most likely needed for younger people who want to return to cutting and pivoting sports. Older or less active people with a stable knee may do well with a brace and therapy. A randomized trial in young active adults found that starting with structured rehabilitation, with surgery later if needed, gave results similar to early reconstruction at 2 years. Return to sport after surgery often takes six months or more. Frobell et al., N Engl J Med 2010 · ACL page

A root tear is a tear at the point where the meniscus anchors to the shinbone, and it stops the meniscus from cushioning the joint. In a Mayo Clinic matched comparison of 45 patients with medial meniscus root tears, none of the 15 who had a repair needed a knee replacement after an average of about six years, compared with 4 of 15 treated without surgery and 9 of 15 treated with partial meniscectomy (trimming). Arthritis progressed less after repair. Patient-reported scores were not significantly different between groups.

Source: Bernard et al., Medial meniscus posterior root tear treatment: a matched cohort comparison, Am J Sports Med 2020;48(1):128-132, doi 10.1177/0363546519888212.

Limits of the evidence: Small study (45 patients), retrospective, not randomized, and several authors disclose industry relationships (Arthrex and others). Better alignment and little arthritis may make trimming reasonable in selected patients, per the paper.

A systematic review of five studies (about 400 patients) compared microfracture with autologous chondrocyte implantation (ACI) at an average of seven years. Treatment failure was similar: 18.5% with ACI and 17.1% with microfracture, and most knee scores improved similarly in both groups. Microfracture is simpler and cheaper; ACI needs two procedures. Microfracture tends to work best on smaller defects.

Source: Kraeutler et al., Microfracture versus autologous chondrocyte implantation for articular cartilage lesions in the knee: a systematic review of 5-year outcomes, Am J Sports Med 2018;46(4):995-999, doi 10.1177/0363546517701912.

Limits of the evidence: Only five studies, mostly older first-generation ACI. The senior author discloses industry consulting.

Knee osteoarthritis is "wear-and-tear" arthritis: the smooth cartilage that cushions the thigh bone, shin bone and kneecap thins and roughens, and over time bone can rub on bone. It causes pain with walking, stairs and getting up from a chair, stiffness after rest, swelling, and sometimes grinding or a knee that feels like it gives way. X-rays show narrowing of the joint space and bone spurs. OrthoInfo: osteoarthritis of the knee · Van Manen et al., J Am Osteopath Assoc 2012

There is no cure, but treatment can control symptoms for years: weight loss if needed, exercise and physical therapy, acetaminophen or anti-inflammatory medicine, and sometimes injections. Knee replacement page

Hip osteoarthritis is the same wear process in the ball-and-socket joint of the hip. It mostly affects people over 50, and risks include family history, a past hip injury, obesity and hip dysplasia. The main symptom is pain that develops slowly, usually in the groin and sometimes spreading to the buttock or knee, with stiffness, a limp, and pain that is worse in the morning or after sitting. X-rays show a narrowed joint space and bone spurs. OrthoInfo: osteoarthritis of the hip

First-line treatment is activity changes, lower-impact exercise such as swimming or cycling, weight loss, physical therapy, a cane when needed, and medicines including acetaminophen, anti-inflammatories and sometimes a steroid injection. Hip replacement page

No. Many people with arthritis never need surgery, and X-ray findings alone do not decide it. Surgery is considered when pain is limiting daily life and has not responded to a real trial of non-surgical care. For the knee, commonly cited indications are advanced arthritis on X-ray, pain that limits daily activities or wakes you at night, and symptoms that persist after about 6 months of non-surgical treatment. For the hip, AAOS describes surgery as an option when arthritis pain causes disability and is not relieved by non-surgical treatment. Van Manen et al., 2012 · OrthoInfo: hip

When the arthritis is advanced, replacement works well. In a Danish randomized trial of people with moderate to severe knee arthritis, those who had knee replacement plus non-surgical treatment had more pain relief and better function after one year than those who had non-surgical treatment alone, though surgery also carried more serious complications. Skou et al., N Engl J Med 2015

Excess weight adds load to the knee and hip with every step, so even modest weight loss can reduce pain. The AAOS gives its strongest recommendation to a trial of diet and exercise for weight loss in knee osteoarthritis, and the authors of one review note that each knee carries several times body weight with every step, so a small loss substantially reduces joint load. Van Manen et al., J Am Osteopath Assoc 2012 Low-impact exercise such as swimming or cycling is a good way to stay active while protecting the joint. OrthoInfo: hip osteoarthritis

In the direct anterior approach (DAA), the surgeon reaches the hip from the front, working between muscles rather than cutting through them. Dr. Stepanyan performs direct anterior hip replacement. Studies (summarized in a JAAOS review by Post and colleagues) show that patients may have less pain and faster early recovery, with the advantage mostly gone by about six months. Dislocation after DAA is low, reported at roughly 1% to 1.5% in the studies reviewed, although the review notes that larger femoral heads have lowered dislocation rates with all approaches. Possible approach-specific issues include numbness on the outer thigh from irritation of a small skin nerve (usually improves), and a learning curve for the surgeon.

The review concluded that DAA is a viable, comparable alternative, but that it had not been shown to give better long-term results. Your surgeon's experience with a given approach is probably more important than the approach itself.

Source: Post ZD, Orozco F, Diaz-Ledezma C, Hozack WJ, Ong A. Direct anterior approach for total hip arthroplasty: indications, technique, and results. J Am Acad Orthop Surg 2014;22(9):595-603, doi 10.5435/JAAOS-22-09-595.

Limits of the evidence: 2014 review; several authors disclose industry relationships.

Traditional knee replacement aims to set the components square to the leg's mechanical axis, which gives every patient the same "neutral" alignment. But natural knees vary a lot. Many people are naturally slightly bow-legged, and forcing them to neutral can require releasing (cutting) ligaments to balance the knee. Kinematic and functional alignment aim instead to recreate each patient's own pre-arthritis knee position and joint line, using as few releases as possible. Dr. Stepanyan uses a functional alignment approach, matching the knee position in three dimensions to native anatomy within reason, making small adjustments when the knee needs them to balance, and minimizing releases.

The research so far is encouraging but not settled. A meta-analysis of nine studies (Courtney and Lee, J Arthroplasty 2017) found kinematic knees had higher Knee Society Scores (about 9 points) and similar complication rates at an average of about three years, with survival of 97.4%. A randomized trial from Auckland (Young and colleagues, Clin Orthop Relat Res 2017;475:9-20) found no difference in patient-reported function at two years, and its authors urged caution because the tibial component sat in more varus and long-term durability is unknown. Both papers stress that results are short-term and that large deviations from neutral performed poorly, which is why the goal is to match native anatomy "within reason."

Sources: Courtney PM, Lee GC. Early outcomes of kinematic alignment in primary total knee arthroplasty: a meta-analysis of the literature. J Arthroplasty 2017;32:2028-2032, doi 10.1016/j.arth.2017.02.041. Young SW et al. No difference in 2-year functional outcomes using kinematic versus mechanical alignment in TKA: a randomized controlled clinical trial. Clin Orthop Relat Res 2017;475:9-20, doi 10.1007/s11999-016-4844-x.

Limits of the evidence: Both papers are from 2017, before today's robotic and navigated techniques, and they study kinematic alignment with patient-specific guides, which is related to but not identical to the functional alignment Dr. Stepanyan performs. The meta-analysis includes single-surgeon series with disclosed financial conflicts, and the trial received Stryker funding.

Most people return to the low- and moderate-impact activities they enjoy. The American Association of Hip and Knee Surgeons (AAHKS) says low-impact sports are recommended after hip replacement, medium-impact sports should be approached carefully, and high-impact sports such as running should be avoided because they stress the implant and may contribute to loosening. It advises starting to return to sport within the first three months, and most patients in the studies it cites were back to their sports within 4 to 6 months. AAHKS: resuming sports after hip replacement

For the knee, AAHKS reports that the majority of doctors do not recommend high-impact sports, and that people who played high-impact sports before surgery more often return to medium- or low-impact ones. The right answer depends on your implant, your bone and your sport, so talk through your goals before surgery. AAHKS: resuming sports after knee replacement

For most people, no. In December 2024 the American Academy of Orthopaedic Surgeons (AAOS) and AAHKS, working with the American Dental Association and infectious disease groups, updated their guideline. It states that routine antibiotics before dental procedures in people with a hip or knee replacement may not reduce the risk of later joint infection, and no study they reviewed showed that they did. Whether an individual patient is an exception is a decision to make with your surgeon. AAOS press release

A 2025 pooled analysis of four studies covering 157,466 patients found infection rates of 0.07% to 0.3% with antibiotics and 0.07% to 0.18% without, with no meaningful difference. Good dental hygiene and regular dental care remain important. Journal of Arthroplasty meta-analysis, summarized by DrBicuspid

Dr. Stepanyan agrees with this guidance: antibiotics are not needed for a routine cleaning. If a dentist is treating a severe active infection, the dentist may prescribe antibiotics for that infection.

Blood clots in the leg veins, which can travel to the lungs, are one of the main risks after hip and knee replacement, because surgery and reduced movement make blood more likely to clot. A short course of blood-thinning medicine lowers that risk. In the large EPCAT II trial of 3,424 hip and knee replacement patients, low-dose aspirin (81 mg) was as effective as the prescription blood thinner rivaroxaban for preventing symptomatic clots: 0.64% with aspirin versus 0.70% with rivaroxaban, with similar bleeding rates. Anderson et al., N Engl J Med 2018 (via ACC summary)

In that trial aspirin was taken for 9 days after knee replacement and 30 days after hip replacement, after a few days of rivaroxaban. Aspirin is the current standard of care and is as effective as other drugs for preventing clots after joint replacement. Newer studies are asking whether some patients might do better on a different blood thinner such as apixaban (Eliquis), but so far aspirin remains the standard. Walking early, ankle pumps and staying hydrated also help. Patients who already take a blood thinner, or who have had clots before, may be given something different.

Sometimes, but only after a work-up. A Philadelphia surgeon reviewed 184 patients who had a cortisone injection into a replaced knee, usually a median of about 5 months after surgery, for a slow recovery or for lasting pain, swelling or stiffness. Every patient was examined, had X-rays and had infection blood tests (ESR and CRP) first, and an aspiration was done if those were abnormal. Of the 129 who answered a survey, 84% reported some improvement, 51% reported moderate or great improvement, and 56% had relief lasting more than a month. Six patients reported minor side effects, and none developed a joint infection within a year. Klement et al., J Arthroplasty 2019

Limits of the evidence: the study was retrospective, from one surgeon, and relied on patients recalling the injection. The authors do not endorse routine injections, and infection is the concern, so a painful or swollen replaced knee must be checked for infection before any injection.

A revision is an operation to replace or repair part or all of a hip or knee replacement that has worn out, loosened or failed. AAHKS lists the main reasons for knee revision as infection (the most common), loosening, instability, wear of the plastic liner, and a fracture around the implant. About 12,000 knee revisions were done in the US in 2019. AAHKS: revision knee replacement

Revision is usually longer and more complex than the first surgery. It may mean a larger incision, removing scar tissue and old cement, and using larger or stemmed implants; recovery typically takes 3 to 4 months, and some studies report 1 to 2 years for full recovery. AAHKS recommends a surgeon experienced in revisions. Revision knee page · Revision hip page