When Is Joint Replacement Needed? A Complete Guide

Joint replacement is needed when arthritis of the hip or knee has reached stage three or four on X-ray and the patient's walking, stair climbing and sleep are steadily getting worse. Earlier stages call for activity modification and medicines, not surgery. In children and young adults the trigger is a joint destroyed by disease or injury, and in the very old the deciding factor is physiological fitness, not age.

That framework opened the masterclass on recent advances in joint replacement given on 12 May 2024 by Dr. Ishwar Bohra, Senior Director - Joint Replacement Programme, BLK-Max Super Speciality Hospital, New Delhi, India, to international doctors, with live French translation for francophone colleagues. Before turning to technology, he set out how a referring doctor decides that a damaged joint has moved beyond conservative care, because the most advanced implant is only as good as the decision to use it.

This guide covers that decision: the two tests that establish it, the stages of disease, the indications beyond osteoarthritis, age at both ends of life, and what a patient can expect afterwards. Two companion articles go deeper. One covers AI, navigation, robotics and the direct anterior approach to the hip, along with arthroscopic shoulder stabilisation. The other covers preparing a patient for joint replacement, from screening and haemoglobin to infection risk and nutrition. The questions doctors asked during the session, including on clubfoot, spinal cord injury and nerve conduction studies, are answered on the Live Discussion page.

The two tests that decide: an X-ray and a careful history

Most orthopaedic problems, in Dr. Bohra's view, can be worked out with the first investigation: a plain X-ray. The film shows three things that together indicate how significant the arthritis is:

• Alignment: whether the limb still runs straight through the joint or has drifted into a deformity.
• Degeneration: the changes in bone that mark worn cartilage.
• Joint space: the gap between the bone ends, which narrows as the cartilage that normally fills it is lost.

The X-ray is read alongside the patient's own account. The symptoms that matter are functional: difficulty walking, climbing stairs up and down, and getting in and out of a car, together with resting pain at night. The most useful question is what the patient could do before. Dr. Bohra's example was a patient who walked 8 kilometres a year ago and now develops stiffness, discomfort or pain in the knee, hip or shoulder after 2 or 3 kilometres. Any loss of a previously normal activity of that kind is, in his words, among the earliest clinical signs of the disease.

Neither test is sufficient alone. An X-ray with mild changes in a patient with severe disability, or a badly worn joint in a patient who still walks freely, each calls for a different conversation. Taken together, the history and the film tell the doctor whether the patient has early arthritis or a joint that has run out of options.

Early arthritis: a stage where the patient can still change course

When the history and the X-ray show the beginning of arthritis, the first step is not a prescription but a change in behaviour. Dr. Bohra advises the patient to modify activity and stop overstretching the joint in the way he or she did before, to give it time to heal. He regards this as the stage at which progression can be slowed and symptoms relieved.

Alongside activity modification, he uses medicines intended to support cartilage healing, which are widely available under different brand names: glucosamine, chondroitin and collagen peptides, combined with exercise. Major guidelines take a more cautious line on these supplements: the 2019 American College of Rheumatology and Arthritis Foundation guideline recommends against glucosamine and chondroitin for knee and hip osteoarthritis, because trials have not shown consistent benefit. The exercise and load management that accompany them are, by contrast, core recommendations in the major guidelines.

How arthritis progresses: the limp and its knock-on effects

Many patients do not present at this early stage. A patient who carries on with pain eventually begins to limp, and Dr. Bohra described the limp precisely: the gait changes so that the patient tilts with every step, one hip dropping while the other rises.

The limp is not a local problem. Once a patient starts limping, the abnormal gait begins to affect other joints of the body, the spine in particular. The X-ray at this point looks different, with more deformity, and the patient's day-to-day quality of life is poorer. This is the stage two to three arthritis at which, in his words, the patient needs some intervention, and it affects the shoulder, hip and knee alike.

When is joint replacement needed?

The most common indication for hip and knee replacement is age-related osteoarthritis at stage three and above. Dr. Bohra describes stages three and four as the stage at which joint replacement is indicated in both the hip and the knee, when symptoms justify it.

At this stage the X-ray confirms the damage, and when pain and loss of function persist despite non-surgical treatment, surgery is the only option that restores the joint. The doctor's job is to counsel the patient honestly that waiting will not help, and that the choice is either to live with the joint as it is or to have the operation. One of the radiographs he presented was of a very young patient with a defect on the medial (inner) side of the joint who, he said, needed some support as well as the knee replacement itself.

Indications beyond osteoarthritis

Osteoarthritis is not the only route to a replaced joint. Dr. Bohra listed the other indications he sees:

• Rheumatoid arthritis, the autoimmune inflammatory arthritis that erodes several joints at once.
• Trauma: post-traumatic malalignment of the hip or knee can lead to arthritis.
• Other autoimmune arthritis and gout.
• Systemic illness and coagulopathies (bleeding disorders such as haemophilia, in which repeated bleeding into a joint wears it out).
• Avascular necrosis of the hip, the death of bone in the femoral head when its blood supply fails. He sees a large number of post-COVID cases, which have become another major reason for hip replacement.

Three joints, two different problems

Dr. Bohra's practice covers the three major joints, the hip, knee and shoulder, and his framework applies equally to all three. The shoulder, however, presents differently with age: younger patients tend to present with instability, such as a traumatic tear of the labrum (the rim of cartilage that deepens the socket), while older patients present mainly with pain. The surgical answer to recurrent instability is covered in the article on advances in technique.

Joint replacement at any age: young adults, children and the very elderly

Age is not a fixed barrier to joint replacement in Dr. Bohra's practice: at the younger end the criteria are driven by the durability of the implant and the completion of bone growth, and at the older end by physiological fitness. Patients routinely ask whether they are too young or too old. Early knee replacements lasted only about 10 years. Modern implants are in what he described as the third generation of knee replacement, and registry data show about 82% of knee replacements still functioning at 25 years. That change has moved the lower limit of age considerably.

Young adults

Younger patients generally need a knee replacement for post-traumatic arthritis, where an accident has destroyed cartilage that cannot be reconstructed. The same applies to the hip when the joint can no longer be kept congruent and its cartilage is completely damaged.

Hip problems are more frequent than knee problems at a young age, from conditions such as congenital (developmental) dislocation of the hip and Perthes disease (a childhood loss of blood supply to the femoral head). Hip replacement can be done once bone growth is complete, which Dr. Bohra placed at 18 years of age; after that, it can be done at any time. He sometimes replaces hips earlier still in special cases, such as sickle cell disease and haemophilia, where the joint is badly damaged and painful.

His arithmetic for the knee is simple. Because most implants now last 25 years or more, a patient with severe difficulty walking at 20 can have a knee or hip replaced and, if needed, revised in middle age. In his words, that is not a bad deal: the patient spends those decades walking, productive and pain-free.

Children

Joint replacement in children is uncommon, but Dr. Bohra does perform it. The hip conditions that can lead to it include slipped capital femoral epiphysis (SCFE, in which the head of the femur slips off the neck at the growth plate), avascular necrosis, Perthes disease, a traumatic hip fracture, and septic arthritis of infancy (Tom Smith arthritis). In such a joint there is no growth potential left, so the bone will not grow, and a replacement at least gives the child a painless life.

The difference in growth between the two legs is then managed on the other side. Arresting growth at the opposite limb's growth plate, an operation known as epiphysiodesis, prevents a limb length discrepancy.

The knee can be affected in the same way. Haemophilia, sickle cell disease, viral arthropathy, other infections and injuries can wear out a child's knee completely. In those cases replacement is sometimes unavoidable, and in his experience the children do very well.

The very elderly

At the other end of life, the decision depends entirely on the patient's medical condition. Dr. Bohra's team has performed hip replacement in a patient aged 104. His conclusion is that age is only a number: it is the physiological age, not the numerical one, that matters. For a different surgeon's view of the same question, see Dr. Subhash Jangid on the age limit for joint replacement.

Outcomes after joint replacement: implant life and high flexion

About four in five knee replacements, and more than half of hip replacements including older designs, are still functioning 25 years after surgery, so for most patients the operation is a long-term solution rather than a temporary one. The prognosis today, in his view, is very good, because patients can do everything they need to.

Function has improved as much as durability. Dr. Bohra now performs hip replacement designed for high flexion, and many of his patients are back to praying in the kneeling position, and squatting, three months after surgery. For patients whose daily and religious life depends on deep bending, that is a meaningful change from older implants.

Alternatives to joint replacement surgery

Not every patient with an indication wants an operation. For a patient who is afraid of replacement or declines it, Dr. Bohra outlined the alternatives:

• Braces, and a cane or stick in hand.
• Lifestyle modification.
• Medicines such as analgesics.
• Supplements to support the bone: calcium, vitamin D, glucosamine and collagen peptides.
• Alternative therapies the patient may wish to try.

These measures relieve symptoms; they do not restore a joint that has reached stage four. The cost of waiting is the limp, the strain it places on the spine and other joints, and a steadily narrower life.

Joint replacement cost and the pathway to treatment

Dr. Bohra explained that the cost of a joint replacement at BLK-Max is set by the hospital's commercial team once the surgical team has studied the case and decided which procedures the patient needs, so it varies from case to case. For standard cases, the hospital has packages for unilateral and bilateral knee and hip replacement. Indicative costs are on Jivo Healthcare's pages for unilateral total knee replacement and unilateral total hip replacement.

Dr. Bohra returned to the same subject the following year, in a separate masterclass on degenerative joint disease, which goes further into diagnosis and staging, joint-preserving surgery and revision. More orthopaedic masterclasses are collected on the orthopaedics specialty page.