Complex Total Hip Arthroplasty

Complex total hip arthroplasty (complex hip replacement) is hip replacement in a joint that trauma, disease or earlier surgery has distorted: a fractured or eroded acetabulum (the hip socket), a dead femoral head, a dysplastic hip or a failed implant. Unlike a routine replacement for simple osteoarthritis, which takes 40 to 45 minutes, it demands days of planning, specialised implants and two to two and a half hours of surgery.

Dr. Rakesh Mahajan, Vice Chairman & HOD - Orthopedics, BLK-Max Super Speciality Hospital, New Delhi, India, has practised orthopaedics since his postgraduate training in 1986 to 1987 and now performs 400 to 500 hip replacements a year, a substantial share of them complex. This guide sets out how he defines a complex hip, how he decides between replacement and joint preservation, what patients can expect from the implant, and what the operation costs. Two companion articles go deeper: one on how acetabular reconstruction in complex hip replacement is planned, from 3D CT to custom implants and the surgical approach, and one on revision hip replacement and the conditions and failed implants behind it.

Why hip disease is so disabling

A damaged hip disables more completely than other degenerating joints, because it compromises walking itself. Dr. Mahajan draws a sharp line here: a patient can carry on, for a time, with knee arthritis or a degenerative spine, but a damaged hip, in his words, never allows the patient to move freely. That is why hip pathology so often ends in surgery, and why getting the first operation right matters.

The specialty has changed around him. When he trained, orthopaedic surgeons were generalists, and arthroscopy in the 1990s meant looking through a lens with the naked eye. Today there are dedicated hip, knee and shoulder replacement surgeons, and arthroscopy runs on high-resolution cameras and monitors that magnify every structure. Complex hip arthroplasty is a product of that refinement: it depends on imaging, implants and surgical experience that did not exist a generation ago.

Complex total hip arthroplasty versus simple hip replacement

A primary total hip replacement (THR) for straightforward osteoarthritis is, in Dr. Mahajan's description, a very straightforward operation that an experienced surgeon finishes in 40 to 45 minutes. Complex primary and revision hip replacements are different in kind. They can take two to two and a half hours, require hardware that must be ordered in advance, and leave little margin for improvisation once the joint is open.

He observes that primary osteoarthritis of the hip is comparatively less common in India than in Western, African and CIS countries, and a steady stream of complex cases reaches him from those regions.

What makes a hip complex

The conditions that turn a hip replacement into a complex operation fall into four groups:

• Trauma. Acetabular fractures that heal out of position or fail to unite, and femoral neck or intertrochanteric fractures whose fixation has failed, leading to post-traumatic arthritis.
• Loss of blood supply. Avascular necrosis of the femoral head, where the bone dies and collapses, including the avascular necrosis seen in sickle cell disease.
• Abnormal development. Developmental dysplasia of the hip (a hip that is dislocated or unstable at birth), the after-effects of a childhood hip infection, and bony growths such as osteochondromas that distort the anatomy.
• Previous surgery. Aseptic loosening, dislocation, osteolysis (bone loss around the implant), fracture around an implant, infection and retained hardware.

Of these, Dr. Mahajan identifies dysplastic hips, avascular necrosis and post-traumatic arthritis as the most common indications for complex hip replacement. Severe deformity, a stiff or fully fused (ankylosed) hip, earlier unsuccessful treatment and significant muscle weakness add further layers of difficulty. Each condition, with the cases he presented, is covered in the article on complex and revision hip replacement.

Diagnosis before hip replacement: pain is a symptom

Pain is a symptom, not a diagnosis, so the cause must be found before any operation is chosen. The principle that runs through Dr. Mahajan's approach is that a patient's request does not set the operation. If a patient arrives asking for a total hip replacement, he will not simply do it, because identifying the actual problem comes first. The cause may be instability, or a leg length discrepancy that is troubling the patient and loading the spine, and each calls for a different solution.

His advice to surgeons is blunt: take your time, do not hurry, plan for everything and think beyond the obvious. Complex hip replacement, he says, is complex mathematics; the surgeon has to work out the best combination of implant and approach before the first incision.

Alternatives to hip replacement: arthroscopy and stem cells

Not every painful hip needs a new joint: where the joint space is preserved, Dr. Mahajan prefers hip arthroscopy with stem cell therapy. His first step is therefore a plain X-ray to assess the joint space.

Pain with preserved joint space

Where pain has started but the patient remains mobile because the joint space and cartilage are maintained, he does not recommend hip replacement straight away. The alternative is hip arthroscopy (keyhole surgery through small portals), in which he clears away the extra bone formation and the damaged part of the cartilage, then repairs the cartilage with stem cell therapy.

Once CT or MRI shows that the cartilage is completely destroyed and there is no blood flow to the femoral head, hip replacement is the only answer.

Femoroacetabular impingement and sports injuries

Femoroacetabular impingement (FAI) is a mismatch in shape between the femoral head and the acetabulum that makes them pinch against each other. It takes two forms: cam, where the head-neck junction is not round, and pincer, where the socket rim over-covers the head. In young, active people, sports such as football, basketball and hockey can damage the cartilage or the labrum (the ring of cartilage around the socket), and Dr. Mahajan describes how that damage, in the setting of cam or pincer impingement, progresses to irreparable cartilage loss and arthritis.

Dr. Mahajan's treatment for FAI is arthroscopic: he removes the impingement, cleans the cartilage and adds stem cell therapy, then allows the hip about six months to regenerate before a repeat MRI. He reports wonderful results with this approach.

He distinguishes these injuries from hip arthritis. Most sports damage involves ligaments or osteochondral defects (injuries to cartilage and the bone beneath it), not arthritis. He treats such injuries with platelet-rich plasma (PRP) injections, stem cell therapy and arthroscopic repair of ligament injuries, and athletes are typically back to high-level sport after about six months.

How stem cell therapy works in the hip

Stem cells, as Dr. Mahajan explains them, are progenitor cells that can turn into the cell type a tissue needs: bone-forming osteoblasts or cartilage-forming chondroblasts. In the hip the target is small islands of damaged cartilage. He cleans these arthroscopically and injects the cells. On follow-up MRI the cartilage begins to fill in, which he likens to grass growing, and over about six months the patient's symptoms ease.

In orthopaedics the cells are harvested from the iliac crest, the upper rim of the pelvis. A needle is passed into the bone from the back or the front, about 120 ml is aspirated from the marrow, and the aspirate is spun in a centrifuge for 45 minutes to an hour. The resulting concentrate is then injected. This preparation is generally known as bone marrow aspirate concentrate (BMAC).

Evidence for cell-based cartilage repair in the hip is still developing, and major orthopaedic guidelines do not yet include it as standard care for hip arthritis.

Children and adolescents

Dr. Mahajan does not recommend hip replacement below 17 or 18 years of age; his rule is to wait. In younger patients, including children with sickle cell disease, he relies on hip arthroscopy to clean up the damage, or on osteotomy: cutting and realigning the bone, as in a valgus or varus osteotomy, to change the weight-bearing surface of the hip. MRI shows where the main damage lies, and the osteotomy shifts load away from it onto healthier cartilage, which relieves pain markedly.

Sport after hip replacement

Most athletes can return to most of their activities after hip replacement, but not to high-impact sport. How much depends on the underlying pathology and on the activity: a long-distance runner, for example, needs a different type of hip replacement. Dr. Mahajan does not promise certainty. Sports with heavy jumping and impact, such as football and basketball, are not ones to continue after a total hip replacement; he advises such athletes to change their sport.

For most patients the measure of success is simpler. Arthritis destroys the cartilage, deforms the anatomy and stops the patient carrying out daily routine activities. A pain-free hip that restores that routine, he says, gives enormous satisfaction.

How long a hip replacement lasts

Pooled registry data show that about three in five hip replacements, including older designs, are still functioning 25 years after surgery, and a well-fixed modern uncemented hip may last longer. Asked whether, since most hip replacement patients are older, most will never need a second operation, he agreed.

Longevity depends partly on the patient. Certain positions load the implant in ways that can loosen it, and Dr. Mahajan advises patients after hip replacement to avoid:

• sitting on the floor;
• sitting cross-legged;
• squatting;
• high-energy and high-impact sports.

Patients who follow these precautions, he says, protect the implant and extend its life.

Hip replacement cost in India

Dr. Mahajan put the cost of a hip replacement at about 7,000 to 8,000 US dollars, down from roughly 10,000 to 12,000 US dollars previously. He attributes the fall to the implant market. International manufacturers once supplied most of the revision and complex hip hardware used in his practice but have since withdrawn much of it, which he links to duties and government policies. Two or three Indian manufacturers, working in collaboration with the international firms, now supply cost-effective alternatives.

Two further factors shape the bill. Cemented implants cost less than uncemented ones, a trade-off discussed in the planning article. And where a patient's finances are stretched, Dr. Mahajan reduces his own surgical fee. For indicative package prices, see the cost of unilateral total hip replacement.

How to refer a complex hip case from abroad

A brief clinical history and basic X-rays are enough to start. For doctors in countries where complex revision hardware or experience is scarce, the question is when a patient needs care abroad, and Dr. Mahajan's answer is to share the case early. With the history and X-rays, he can advise on the best option, the approximate length of stay and the approximate cost. He also sees value in regular case-discussion sessions, once a month or once every two months, at which doctors bring their patients' X-rays and reports for a view on whether surgery will help and what the total stay and expense would be. The questions doctors put to him during this masterclass, on cost, athletes, sickle cell disease and stem cells among others, are collected in the Live Discussion.

Related reading

Dr. Mahajan has also taught separate masterclasses on robotic knee replacement and on joint pain in younger patients. More hip and joint content sits in the orthopaedics specialty hub.