Hip and Knee Replacement Surgery

Hip and knee replacement surgery replaces a joint destroyed by end-stage osteoarthritis with an artificial implant. Dr. Ramkinkar Jha, an orthopaedic surgeon with a special interest in joint replacement, ligament reconstruction and arthroscopy, offers it from age 18 with no fixed upper age limit, selects patients by pain and disability rather than X-ray grade, and puts the average life of a primary implant at 20 to 25 years.

Joint replacement is the last rung of a long treatment ladder, not the first answer to a painful joint. Dr. Jha frames the operation around a single test: does it return the patient to the life and work the arthritis took away? Everything else, from the choice of implant to the use of a robot, is judged against that outcome.

This guide sets out how he decides who needs a new joint, which joints can be replaced, what can go wrong, how long an implant lasts and what life looks like afterwards. Two companion articles go deeper: one on osteoarthritis diagnosis and treatment before replacement, and one on complex and revision joint replacement, implants and robotics.

Why joints need replacing: end-stage osteoarthritis

Almost every joint replacement treats the end stage of osteoarthritis, a disease in which the cartilage lining the joint is eroded and the joint space it occupied is lost for good. Treatment escalates in three tiers: non-invasive care (physiotherapy and medication), less invasive measures (injections into the joint), and surgery. Surgery itself runs from keyhole arthroscopy, through corrective osteotomy (cutting and realigning the bone) and partial knee replacement, to total joint replacement. How the disease is diagnosed, and the clinical judgement that moves a patient up that ladder, are covered in the osteoarthritis article.

What hip and knee replacement is meant to achieve

Joint replacement aims to relieve pain, improve quality of life and preserve or improve joint function. Dr. Jha separates the goals of the operation into two perspectives that converge on one destination.

• The surgeon's goals are technical: restore alignment, build a stable construct, and increase the range of motion.
• The patient's goals are practical: walking that is pain-free, early and independent.
• The shared destination is functional: restored motion and a return to the patient's own working and personal life.

The framing matters because it sets the standard for technology later in the pathway. A tool that improves the surgeon's measurements without changing the patient's function is, in his view, not a reason on its own to pay more.

Which joints can be replaced?

The hip and the knee are the most commonly replaced joints. In Dr. Jha's region the two are performed in roughly equal numbers, a ratio of about 1 to 1. Then come the shoulder and the elbow, with finger joints replaced only rarely, mostly in rheumatoid arthritis. Hip, knee, shoulder and elbow together account for about 95 per cent of replacements, by his account.

The ankle is the notable gap. Ankle replacement is not offered in his setting: an earlier implant design was used in the past, but its outcomes were poor and it was withdrawn. For an ankle destroyed by an old fracture, the treatment he describes as both the simplest and the most durable is ankle arthrodesis, a fusion of the joint that relieves pain and leaves the ankle stable.

Who is a candidate for joint replacement?

A candidate is a patient whose pain and disability persist despite medical therapy and physiotherapy, who is at least 18 and who is medically fit for surgery.

Is there an age limit for joint replacement?

The lower limit today is 18, once growth is complete. There is no fixed upper limit: the ceiling is set by medical fitness, not by the calendar. Asked about patients over 85, Dr. Jha was unequivocal: a 100-year-old who is fit for surgery can have the operation.

The rule was once different. When implants were less developed, replacement was reserved for patients over 60 or 65. Two things changed that: implants improved, and patients' expectations rose. Dr. Jha's example is a 25-year-old with advanced arthritis who cannot move. Asking that patient to wait 40 years for a new hip or knee would sacrifice their working life and their personal life.

Disability and pain decide, not the X-ray

The decision to operate rests on a detailed clinical evaluation of two things: how much pain the patient has, and how far it restricts their activities. Several disability scoring systems exist to quantify it, but the judgement is clinical. A patient with high disability is a candidate for total joint replacement. A patient whose activities of daily living remain intact usually is not, however the joint looks on film.

Dr. Jha is explicit that the X-ray grade does not select patients for surgery, a point developed in the osteoarthritis article. Medical therapy and physiotherapy are the first line. When they fail and the activities of daily living are disturbed, surgery is justified.

Risks and complications of joint replacement

The main complications of joint replacement are infection, loosening, dislocation of the hip, anaesthetic complications and fracture. Outcomes have improved substantially worldwide, provided the operation is well indicated, well planned and well executed.

• Infection. Periprosthetic joint infection, an infection around the implant, affects roughly 1 to 2 per cent of primary hip and knee replacements.
• Loosening. Either septic, driven by infection, or aseptic, a mechanical failure that tends to appear many years after the operation.
• Dislocation. A risk specific to the hip.
• Anaesthetic complications and fractures, which can occur with any major operation on a joint.

The treatment of infection is set out in detail in the complex and revision article.

Persistent pain after joint replacement: what to rule out first

Unexplained discomfort after a replacement should be investigated for infection, loosening and malpositioning before implant allergy is considered. Surgeons are sometimes tempted to blame the metal when a patient reports persistent pain, and Dr. Jha's advice is to treat the implant as inert until proven otherwise. True allergy to implant material is very rare and should not be the first item on the differential diagnosis. The known causes come first: infection, including low-grade subclinical infection, aseptic loosening, and malpositioning of the implant at the original operation. Only when those are excluded is a material reaction worth pursuing.

How long does a hip or knee replacement last?

For straightforward primary replacements, Dr. Jha puts average durability at 20 to 25 years. The range is wide. Some implants fail at around 15 years, and some last 40 or 45. Durability falls in revision and complex cases.

He attaches a condition to those numbers. They assume the patient has looked after the joint: followed the precautions they were given and kept up the physiotherapy and exercises. A survival figure quoted without that prerequisite overstates what any implant can promise.

Activity is the other variable. Every artificial joint wears, and wear accumulates with load. The general counsel to replacement patients is therefore to avoid running and jumping for the sake of the implant's lifespan, because more activity means more wear and a higher chance of revision, a second operation to replace the implant. Athletes who cannot accept that trade-off need a different implant strategy, discussed in the revision article.

Life after hip and knee replacement

Is a joint replacement permanent?

Yes. Joint replacement is an irreversible procedure. A well-functioning implant does not need to be removed or exchanged on a schedule; it stays for life unless a complication intervenes.

Follow-up schedule after joint replacement

Dr. Jha's review schedule is fixed:

1. Two weeks, to remove the stitches.
2. Six weeks after surgery.
3. Three months.
4. Six months.
5. Annually thereafter.

The 90-degree rule after hip replacement

For the first six to eight weeks after a hip replacement, patients are asked not to bend the hip beyond 90 degrees. The restriction protects against dislocation while the joint capsule heals. Dr. Jha notes that the rule is not found in textbooks but is a widely taught convention in training. His fuller answers on follow-up, durability and the 90-degree rule are in the live discussion from his masterclass.

Can you have an MRI after joint replacement?

In most cases, yes. A patient with a replaced joint can have an MRI of that joint or of any other part of the body. Modern joint replacement implants are non-ferromagnetic and are generally safe in standard scanners, within the conditions set out in the implant's MRI labelling. Radiologists sometimes refuse to scan a patient who has a joint replacement, and Dr. Jha regards this as unnecessary in most cases. When the replaced joint itself needs imaging, the scan should use an implant-specific protocol, with adjusted coils and sequences that suppress the artefact the metal creates.

Cost of joint replacement in India

Dr. Jha puts the cost of joint replacement at almost one-third of the price in developed nations. Two factors drive the gap: implants cost less in the Indian market, and so does the surgery itself. Indicative prices are listed for total knee replacement and total hip replacement. Related articles from other surgeons are collected on the orthopaedics specialty page.

Where to go next

• Osteoarthritis diagnosis and treatment before replacement: grading, the clinical gold standard, physiotherapy, medication, the four classes of joint injection, arthroscopy, osteotomy and partial knee replacement.
• Complex and revision joint replacement: implants and robotics: implant materials and bearings, conventional versus navigated and robotic surgery, complex primary and revision cases, tumour reconstruction, shoulder and elbow replacement, athletes and infection.