Diagnostics and indications for surgery
Before referring a patient for arthroplasty, it is necessary to confirm the end-stage of the disease. The main reason for surgery is osteoarthritis (OA) or rheumatoid arthritis (RA).
The diagnosis is based on clinical presentation (pain, limp, flexion contracture) and objective data. Physical examination reveals limb axis deviation (malalignment), effusion (effusion), and range of motion restriction. It is important to remember pseudolaxity of the ligaments: the loss of medial cartilage creates a false impression of collateral ligament injury during stress testing.
The gold standard for diagnostics is weight-bearing radiography. There are 4 cardinal signs of osteoarthritis:
- Joint space narrowing (joint space narrowing) — usually asymmetric, often leading to varus deformity.
- Subchondral sclerosis (subchondral sclerosis) — bone densification in the zone of maximum load.
- Osteophyte formation (osteophyte formation) — marginal bony spurs.
- Subchondral cysts (subchondral cysts).
Ordering an MRI when the diagnosis of arthrosis has already been established is unjustified. Tomography does not affect surgical tactics and is indicated only to exclude osteonecrosis or to search for the source of atypical pain.
The place of surgery in the treatment algorithm
First-line treatment for arthrosis is always conservative: patient education, physical therapy (physical therapy), weight loss, mild analgesics (opioids are not indicated), and intra-articular injections.
Surgical treatment is considered only in case of ineffectiveness of conservative measures AND the presence of severe, disabling symptoms. The lack of response to pills in itself is not a direct reason for surgery if the patient can adapt to the condition.
Important fact: Arthroscopic lavage and debridement for osteoarthritis have been proven ineffective (no better than a sham surgery). Mechanical smoothing of the altered cartilage does not solve the problem of subchondral sclerosis. Arthroscopy is justified exclusively for mechanical symptoms (joint locking) or for the removal of loose bodies.
Essence and options of arthroplasty
If arthritis is isolated to a single compartment (most commonly medial), an alternative to total replacement is unicompartmental knee replacement (uni-compartmental knee replacement).
In case of total involvement, total knee arthroplasty (total knee arthroplasty - TKA) is used. Procedure steps:
- The affected articular ends of the femur (femur) and tibia (tibia) are resected.
- Metal components are installed on the prepared surfaces.
- A plastic spacer (polyethylene insert) is fixed between them to ensure smooth sliding.
- The articular surface of the patella (patella) can be replaced with an artificial one or preserved as native.
Efficacy and prognosis
Although total knee arthroplasty is highly effective, about 20% of patients remain dissatisfied with the results (most often due to unrealistic expectations or persistent residual pain).
The artificial joint is subject to mechanical failure (mechanical failure) and loosening (loosening), which limits its lifespan. Therefore, it is critically important to select patients correctly: the ideal candidate is an elderly person with confirmed end-stage arthritis who has exhausted non-surgical treatment methods.
Briefly: answers to topical questions
What are the absolute and relative contraindications to knee arthroplasty?
Contraindications are described only for partial knee arthroplasty, without division into absolute and relative. They include:
- Frontal deformity — fixed deformity, typically exceeding 15 degrees.
- Contracture — fixed limitation of extension greater than 15 degrees and flexion greater than 90 degrees.
- Widespread process — significant involvement of other compartments of the knee joint in the pathological process.
What early and late complications are possible after total knee arthroplasty?
The following complications are possible after total knee arthroplasty:
- Severe complications — in approximately 1% of patients: infection, thrombosis, cardiovascular events.
- Mechanical failure (mechanical failure) of components over time.
- Component loosening (loosening).
- Perioperative mortality — approximately 0.1%.
Sources do not specify which of the listed complications belong specifically to early or late ones.
What surgical approaches are used in total knee arthroplasty?
Specialized approaches are used for surgical interventions on the knee joint. The materials mention the use of the following options:
- Quadriceps snip approach (quadriceps snip) — approach according to J.N. Insall.
- Osteotomy — approach with tibial tubercle osteotomy.
Other specific surgical approaches for total knee arthroplasty are not described.
To memorize the 4 radiological signs of arthrosis, use the acronym JODS: Joint space narrowing, Osteophytes, Dense bone (subchondral sclerosis), Subchondral cysts.
Class and exam questions
Is it necessary to get an MRI to make a decision on arthroplasty?
No, if the diagnosis of osteoarthritis is confirmed radiologically. Meniscal tears in the setting of arthrosis are part of the degenerative process, and MRI will not change the treatment tactics.
Can one manage with arthroscopy ("joint cleaning") instead of replacement?
In pronounced arthrosis, arthroscopic debridement is ineffective. The procedure is indicated only to eliminate mechanical locking or to remove "joint mice".
Which knee symptoms require urgent attention ("red flags")?
Acute deterioration of symptoms, appearance of effusion, and sharp pain during passive movements. They raise suspicion of septic (infectious) arthritis.
What else to study on this topic
- High tibial osteotomy as a treatment method for localized arthritis
- Differential diagnosis of knee pain (anserine bursitis, iliotibial band syndrome)
- The role of synovial fluid analysis in ruling out gout and infectious arthritis
- Radiological and laboratory differences between rheumatoid arthritis and osteoarthritis
- Basic first-line conservative therapy (physical therapy, lifestyle modification)
Master the entire topic in the "Traumatology" course
This is a summary. The course covers everything tested in classes and exams.
- Full textbook on the topic "Knee Arthroplasty" and 812 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 35 video lessons on the subject
Other Topics in "Orthopedics"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.