Knee revision can be divided into several stages: preoperative preparation, intraoperative technique, and postoperative treatment and rehabilitation, which we also discuss in this order. To avoid repetition, we suggest that the reader read the literature on hip revision.
Although there are different fixation methods for knee revision prostheses, in this article I recommend the cemented fixation method.
Preoperative planning
Different diagnoses
When a patient complains of pain after total knee replacement, the surgeon should identify the cause of the pain, whether it is caused by bone, the implanted prosthesis, the periarticular soft tissue, the periprosthetic nerve, or by other regional derangements.
Pain caused by the internal fixation and the bone is usually due to loosening of either or both, with non-restrictive prostheses often causing tibial pain and posterior stabilized prostheses often causing femoral pain. Loosening of non-cemented prostheses includes failure of biomechanical fixation and secondary loosening, with asymptomatic prosthesis loosening being less common. Even with biomechanical fixation, patients with non-cemented semi-restricted knee prostheses with medullary stems can experience pain, but this does not occur as frequently as with non-cemented total hip replacements. Failure of a nonrestricted prosthesis replacement is not due to loosening, but rather to ligament weakness and/or overstressing of the ligaments causing pain in that area.
In patellofemoral replacements, pain in this region is most often a sign of patellar prosthesis loosening or fracture; in patellofemoral replacements without replacement, arthritis may be the cause of pain. However, even with radiological changes, pain is usually absent or rare. Pain may also occur in cases where the patellofemoral surface has not been cleaned and repaired. Other causes of pain are prosthetic design, mismatch of the implanted prosthesis, etc. Relative anterior displacement of the patellofemoral joint or anterior displacement of the axis of flexion can cause pain when the patella moves laterally.
Although pain can cause abnormal pressure on the bone and soft tissue tension, subluxation of the femoral and tibial prostheses primarily causes sensory instability. A variety of factors can contribute to subluxation, including.
-Insufficient ligament and joint capsule strength following implantation of a non-restrictive prosthesis.
-Insufficient strength of the reconstructed joint capsule, lateral collateral ligaments and periarticular muscles or defective material for implantation of a semi-restricted total knee prosthesis
-material defects after implantation of a fully restricted prosthesis.
Fractures of the femur or tibia in posterior stabilized prostheses, usually near the end of the femoral stalk; fractures of parts of metal prostheses such as prosthetic stalks, condylar prostheses, and articular joint attachments may be the source of pain caused by bone and prosthesis.
Pain associated with soft tissue changes may be the result of scarring, fascial fissures, or tenosynovitis; improper fitting techniques or implantation of insufficiently stable prostheses that cause excessive tension in weak muscles can create nonphysiologic stresses and thus cause pain.
Heterotopic ossification can also occur, but rarely; symptoms similar to sympathetic dystrophy reflex (Sudeck post-traumatic reflex atrophy) may occur after total knee replacement.
Local alterations of the peripheral nerve are one of several major causes of pain; the infrapatellar branch of the saphenous nerve (or anterior branch of the femoral cutaneous nerve, less commonly) may have been severed during a previous surgery and formed a neuroma; or the peripheral nerve may be trapped by the scar of a previous surgery. This can impair sensation in the anterior and infrapatellar regions and present with a positive Tinel’s sign. Pain is reduced with local anesthesia in the painful area and can also occur with common common peroneal nerve injury.
Pain from other parts of the body, especially proximal derangements of the torso, can affect the knee joint. Sometimes pain is caused by hip arthritis or failed hip replacement surgery. Painful symptoms arising from hip replacement can also be attributed to the sacroiliac joint and lumbar spine. Nerves that supply sensation through the hip joint to the skin and planes below the knee may have been damaged during previous hip surgery, producing knee pain. This includes the femoral nerve and its branches, the saphenous nerve, the foraminal nerve, and the sacral nerve.
Every knee surgeon encounters knee difficulties that manifest as persistent pain that is difficult to describe and difficult to localize, both for the patient and the internist. Such pain may have been present prior to the first surgery, persist after surgery and revision, or even persist after joint stiffness. Such patients often experience having psychosomatic abnormalities. The knee joint is more susceptible to psychosomatic problems than the hip joint. However, objective evidence for this suspicion is difficult to find, and this presumed diagnosis is only appropriate for patients who lack a firm conclusion.
As with the hip, periprosthetic infections can be acute or chronic. Chronic infections can include atypical pain or no pain at all, and other typical features of infection may be absent.
The main causes of total knee replacement revision include.
-Aseptic loosening of one or both of the prostheses.
-semi-dislocation or instability between the femur and tibia.
-deformity.
-abnormally increased friction and plastic deformity after polyethylene fitting, which is usually a sequel to excessive weight-bearing after subluxation or deformity and usually occurs when the weight-bearing surface is too small, especially if the articular surfaces are mismatched
-Fatigue fractures of metal components.
-femoral and tibial fractures that are not amenable to internal fixation
-patellofemoral joint pain due to anterior displacement of the patellofemoral joint (whether the patella is not replaced, partially or fully replaced)
-limited movement of the limb, which is not relieved by massage, and limited movement of the joint, which can only be resolved by a second tibial osteotomy
-Uncomfortable for the patient when the knee is hyperextended
-Infection around the prosthesis, which cannot be controlled by irrigation and requires a phase I or II revision to replace the prosthesis.
Revisions that do not include prosthetic replacement are.
-Second hemipelvectomy or total patellar resection
-Surgeries that do not require replacement of the patella after prosthetic replacement, such as osteotomy, drilling, and cartilage grinding
-relaxation of the lateral patellar support band.
- manual release.
-re-excision of the bursa; (mechanism of patellar popping syndrome and surgical clean-up)
-excision of the infrapatellar neuroma with the management of other nerves
-removal of heterotopic ossification
-replacement of the broken prosthetic component
-Placement of a flushing device to attempt to control acute periprosthetic infection, or to control sepsis.
Evaluation of laboratory tests, control of blood products, radiological evaluation
In addition to standard preoperative testing, total knee revision requires biological microscopic testing, blood product control, and certain radiologic studies.
Arthroscopy is important prior to the initial total knee arthroplasty to determine whether there is an indication for replacement or osteotomy and the need for revision. Arthroscopy does not play an important role in total knee replacement revision, and in most cases it is valuable to take a biopsy in cases where periprosthetic infection is suspected and arthrocentesis is not certain.