Revision Hip & Knee Replacement: How Dr. Ali Sobh Corrects Failed Joint Surgeries
When a previous joint replacement fails, revision surgery rebuilds the joint. Dr. Ali H. Sobh, MD explains the causes of implant failure and his fellowship-trained approach to complex revision arthroplasty.
A joint replacement is one of the most reliable operations in medicine, with modern implants designed to last two to three decades. But no lasts forever, and a previous replacement can fail for reasons that have nothing to do with the original surgeon's skill. When a hip or knee replacement becomes painful, unstable, stiff, or infected, the solution is revision — one of the most demanding procedures in orthopedics. Dr. Ali H. Sobh, MD, whose fellowship at Rush University Medical Center included dedicated training in complex revision, is recognized across Metro Detroit for correcting problems from joint replacements performed elsewhere.
Why a Previously Successful Replacement Fails
Patients are often surprised that a replacement which worked perfectly for years has begun to hurt again. Revision is rarely a sign that something went wrong at the time of the original surgery. Instead, it reflects the long, slow biology of a joint living with an . Understanding the cause is the first step in planning the reconstruction, because each failure mode demands a different strategy.
Aseptic Loosening and Osteolysis
Over decades of use, microscopic wear particles shed from the 's bearing surface can trigger the body to resorb surrounding bone — a process called osteolysis. As the bone thins, the loses its grip and loosens, even without infection. This is the most common reason a well-functioning replacement eventually becomes painful. Aseptic produces a characteristic start-up pain — discomfort with the first few steps that eases as the joint warms up — and is clearly visible on X-rays as a gap between and bone.
Instability and Recurrent Dislocation
A hip that repeatedly dislocates, or a knee that feels wobbly and gives way, often indicates that the soft tissues or components can no longer provide stability. This can stem from wear, component malposition, or gradual ligament laxity. Revision restores stability by repositioning components, restoring leg length and offset, or, in the knee, upgrading to a more constrained that mechanically stabilizes the joint.
Stiffness and Arthrofibrosis
Some knee replacements develop excessive scar tissue that blocks motion despite dedicated . When a knee replacement cannot bend enough for stairs or sitting, or cannot fully straighten, the itself or the balance of the joint may be the problem. Revision can address the mechanical cause, sometimes combined with manipulation or scar-tissue release, to restore functional .
Periprosthetic Infection
Infection is among the most challenging complications. A low-grade infection can smolder for years, causing pain, swelling, or warmth around the joint without obvious systemic signs. Treatment typically follows a two-stage protocol: Dr. Sobh removes the infected , places an antibiotic-loaded cement spacer to maintain joint space and deliver high-dose local antibiotics, and works with infectious disease specialists to clear the infection before re-implanting a new, clean joint. This staged approach offers the best long-term chance of eradicating infection and restoring function.
Periprosthetic Fracture
A fall or trauma can fracture the bone around an , particularly if osteolysis has weakened the bone. These fractures often require revision to stabilize the bone with long-stemmed implants, plates, or grafts — sometimes addressing the that predisposed the bone to fracture in the first place.
A well-functioning, painless joint replacement does not need revision. 'Preventive' revision is never recommended — the risks of surgery outweigh any hypothetical benefit. Revision is indicated only when a replacement has become genuinely painful, unstable, stiff, infected, or fractured. The first step is always an accurate diagnosis of why the joint has changed.
Why Revision Is Far More Complex Than the Original Surgery
Primary joint replacement places implants into native bone with predictable anatomy. Revision begins by removing an that is often cemented or bone-grown into bone that has become fragile, deficient, or deformed. Every gram of bone preserved during removal is bone Dr. Sobh can use for the reconstruction; every bit lost must be rebuilt. This is why revision takes longer, demands specialized instruments, and requires a surgeon trained specifically in complex — not every orthopedic surgeon performs revisions.
- extraction: Specialized tools remove the old components without fracturing weakened bone, preserving as much bone stock as possible for the reconstruction.
- Bone stock restoration: Lost bone is rebuilt with morselized or structural allograft, metal augments, sleeves, or cones that integrate with remaining bone to create a stable foundation.
- Component selection: Modular revision stems, cups, and constrained or hinged implants are assembled intra-operatively to match the specific pattern of bone loss and ligament insufficiency.
- Soft tissue and : In the knee, if ligaments cannot stabilize the joint, a more constrained provides mechanical stability so the revision functions reliably.
- Infection protocol: For infected joints, a staged two-stage approach eradicates infection before the new is placed, maximizing long-term success.
Dr. Sobh's Fellowship-Trained Revision Expertise
Dr. Sobh's subspecialty fellowship at Rush University Medical Center specifically included complex revision — training that goes well beyond a standard orthopedic residency. He uses advanced CT imaging and 3D modeling to map bone loss and plan each reconstruction before ever entering the operating room, because in revision, surprises in the OR are the enemy of a good outcome. Patients are referred to him from across Metro Detroit when a previous hip or knee replacement becomes painful, stiff, unstable, or infected, including cases other surgeons have declined to take on.
His revision philosophy mirrors his primary replacement philosophy: preserve tissue, restore biomechanics, and protect long-term survival. You can read more about his revision hip and revision knee services, or explore how his expertise in complex adult reconstruction extends to congenital and post-traumatic deformity.
What Recovery From Revision Looks Like
Revision recovery is longer and more gradual than primary replacement — typically three to six months rather than six to twelve weeks. Your weight-bearing status and range-of-motion limits depend on the extent of bone reconstruction and the stability achieved. Dr. Sobh provides a personalized recovery plan and a dedicated program to protect the reconstruction while restoring strength and mobility. The investment in careful, staged rehabilitation is what makes a durable revision result possible.
When to Seek a Revision Evaluation
If you have a hip or knee replacement that has developed new pain, instability, stiffness, warmth, or a change in your ability to walk, do not wait. Early diagnosis of the cause — whether , instability, infection, or fracture — preserves more options and more bone for the reconstruction. Dr. Sobh sees revision patients at his Royal Oak and Southfield offices and welcomes referrals. Call (833) 667-3627 or book an appointment to schedule an evaluation.
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Sources & References
Editorial Note: This article was last reviewed and updated on September 2, 2025 by Dr. Ali H. Sobh, MD. It is intended for general educational purposes only and does not replace personalized medical advice. Always consult Dr. Sobh or your qualified healthcare provider for guidance specific to your condition.
The Sobh Orthopedics editorial team publishes news, awards, and educational content reviewed by Dr. Ali H. Sobh, MD to keep patients informed and empowered.
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