I. Arthroscopic Management of the Arthritic Knee
A. Overview
1. The use of arthroscopy for the treatment of early-stage osteoarthritis of the knee is growing in popularity as it may delay major reconstructive procedures.
2. Various techniques are described, including lavage and debridement, chondroplasty (laser, radiofrequency), abrasion arthroplasty, and subchondral penetrating procedures (drilling, microfracture).
3. Prognostic factors are listed in
Table 1.
a. Arthroscopic procedures are contraindicated in the knee with advanced arthritis, especially when varus or valgus malalignment is present.
b. The literature is lacking in well-designed studies to evaluate the efficacy of these arthroscopic procedures, and the surgeon must realize the limitations of arthroscopic treatment of the knee.
B. Lavage and debridement
1. Arthroscopic lavage and debridement of the arthritic bone is controversial but effective when properly indicated. The indications are limited to specific mechanical symptoms caused by loose bone, cartilage flaps or particles, meniscal tears, or synovial impingement.
2. The knee is irrigated and debridement of loose cartilage, meniscus, and/or synovium through the arthroscope is performed.
3. The irrigation dilutes the joint fluid, which reduces the concentration of degradative enzymes.
4. The removal of soft tissue reduces mechanical symptoms and removes a source of irritation to the synovial tissue.
C. Chondroplasty
1. Diseased cartilage is removed or stabilized through the use of a shaver, laser, or radiofrequency probe.
2. The potential for thermal damage with the use of a laser or radiofrequency probe has led to decreased use of these techniques.
D. Abrasion arthroplasty
1. An arthroscopic shaver is used to debride cartilage defects and penetrate the subchondral bone plate to cause bleeding.
[Table 1. Prognostic Factors for Arthroscopic Treatment of Degenerative Arthritis of the Knee]
[
Figure 1. Techniques for valgus-producing high tibial osteotomy. A, Lateral closing wedge. B, Medial opening wedge. C, Dome osteotomy.]
2. The goal is to have a blood clot form; this will undergo metaplasia into fibrocartilage, which is estimated to occur in 8 weeks.
E. Subchondral drilling or microfracture
1. Cartilage defects are debrided to a stable rim, and the resulting exposed subchondral bone is penetrated with a small drill or awl.
2. The goal is to create bleeding bone, which will produce a blood clot and subsequent fibrocartilage.
3. The biomechanical and physiologic differences between fibrocartilage and hyaline cartilage are concerning for lasting effectiveness.
II. Osteotomy
A. Overview
1. Osteotomy of the knee is effective for treating arthritis due to a varus or valgus malalignment and can delay the need for total knee arthroplasty (TKA).
2. Currently, osteotomy of the knee is frequently combined with cartilage restoration procedures to provide a better mechanical environment for the biologic repair.
3. Osteotomy of the knee is ideal for the young, active patient with isolated medial or lateral compartment disease because it realigns the limb and reduces stresses on the articular cartilage of the diseased compartment.
B. High tibial osteotomy
1. Medial compartment arthritis (common) in the varus malaligned limb is treated with a valgus-producing high tibial osteotomy.
2. Techniques include lateral closing wedge, medial opening wedge, and dome osteotomy (Figure 1).
3. Slight overcorrection of the varus deformity to 8° to 10° of valgus has produced good results.
C. Distal femoral osteotomy
1. Lateral compartment arthritis (less common) in the valgus malaligned limb is usually treated with a varus-producing distal femoral osteotomy to avoid an oblique joint line (
Figure 2).
2. The goal is to correct the deformity to 0° to 2° of valgus.
D. Contraindications
1. Valgus-producing high tibial osteotomy
a. Lateral compartment arthritis
b. Patellofemoral arthritis
c. Inability to accept cosmetic appearance of leg
d. >15° flexion contracture
e. Range of motion <90°
f. Loss of lateral meniscus
2. Varus-producing distal femoral osteotomy
a. Medial compartment arthritis
b. >15° flexion contracture
c. Range of motion <90°
d. Loss of medial meniscus
e. Patellofemoral arthritis
E. Complications
1. Compartment syndrome
2. Peroneal nerve palsy (usually in high tibial osteotomy)
3. Nonunion or malunion
4. Undercorrection or overcorrection
5. Patella baja
F. Results
1. Valgus-producing high tibial osteotomy has been successful in approximately 50% to 85% of patients at 10 years.
2. Varus-producing distal femoral osteotomy has been successful in 87% of patients at 10 years.
G. TKA after osteotomy
1. TKA after osteotomy is technically challenging because of previous incisions, scar tissue, retained hardware, tibial abnormalities, and femoral abnormalities.
2. Patella baja and increased need for lateral release are common.
3. Survivorship of TKA does not seem to be affected, as several studies have shown excellent long-term results.
III. Cartilage Reparative/Restorative Procedures
A. Overview
1. Patients with large, full-thickness cartilage defects are often symptomatic and present a challenge to the treating orthopaedic surgeon.
2. Techniques that have become available to treat these patients include autologous chondrocyte transplantation, osteochondral autograft, and osteochondral allograft (
Table 2).
3. These procedures are generally limited to the younger patient without global osteoarthritis of the knee.
4. These procedures should be performed on an individualized basis (
Figure 3).
[Figure 2. A varus-producing high tibial osteotomy (A) results in obliquity of the tibiofemoral joint line (B). A varus-producing distal femoral osteotomy (C) results in a horizontal tibiofemoral joint line (D).]
[Table 2. Goals and Source of Chondrocytes for Surgical Treatment of Articular Cartilage Lesions]
[Figure 3. Algorithm for the treatment of articular cartilage lesions. ACI = autologous chondrocyte implantation; OAT = osteochondral autograft transfer.]
B. Autologous chondrocyte implantation
1. Autologous chondrocytes are harvested, manipulated, and expanded in culture and then reimplanted under a periosteal flap.
2. Second-look arthroscopy has shown hyalinelike tissue repair in most patients.
3. This technique is indicated for active patients with a stable, well-aligned knee and a cartilage defect >2 cm.
4. Best results have been with isolated femoral condyle lesions.
C. Autologous osteochondral plug transfer (mosaicplasty)
1. In mosaicplasty, single or multiple small plugs of autologous cartilage and the subchondral bone are transferred to the cartilage defect.
2. Donor sites include the non-weight-bearing regions of the knee (area near the intercondylar notch, lateral femoral condyle superior to the sulcus terminalis).
3. This technique is best suited to lesions that are 1 to 2 cm in diameter.
4. Good results have been obtained on both femoral and tibial defects (usually the anterior third).
D. Osteochondral allograft transplantation
1. Allografts of bone and overlying hyaline cartilage are transplanted into cartilage defects.
2. This technique is often used for large defects (>4 cm) usually due to trauma or osteochondritis dissecans.
3. Concerns include supply of allografts, cell viability, and disease transmission.
4. Several authors have reported good to excellent results in 80% of patients with femoral allografts at 5 years.
IV. Knee Arthrodesis
A. Overview
1. Arthrodesis is usually the last option available to the surgeon to obtain a painless stable knee when the knee is not amenable to a reconstructive procedure.
2. Successful fusion is achieved in >90% of patients.
B. Indications
1. The most common indication is the unrevisable TKA (usually because of infection).
2. Less common indications include septic arthritis, osteomyelitis, posttraumatic arthritis in a young manual laborer, painful ankylosis, neuropathic knee, and paralytic deformity.
C. Contraindications
1. Bilateral knee involvement
2. Ipsilateral hip arthrodesis
D. Surgical techniques
1. External fixation, plates, intramedullary rods (
Figure 4), and combined modalities are used in knee arthrodesis.
2. Position of fusion
a. If the limb-length discrepancy is <2 cm, place the knee in 5° to 7° of valgus and 15° of flexion.
b. If the limb-length discrepancy is 2 to 4 cm, place the knee in extension, because it will be able to clear the ground.
c. If the limb-length discrepancy is >4 cm, consider bone grafting or a prosthetic spacer to limit gait abnormalities.
E. Complications
1. Complications include painful nonunion (most common), infection, deep venous thrombosis, peroneal nerve palsy, and wound dehiscence.
2. Long-term complications include hip, spine, and ankle pain due to the altered gait pattern.
[Figure 4. AP (A) and lateral (B) views of a long antegrade intramedullary nail.]
Top Testing Facts
1. Acute onset of pain, twisting mechanism, mechanical symptoms, recent effusion, and normal mechanical alignment are good prognostic factors for successful arthroscopic treatment of arthritis of the knee.
2. Arthroscopic lavage and debridement of the arthritic knee is controversial but effective when properly indicated.
3. Subchondral drilling/microfracture procedures produce fibrocartilage.
4. Valgus-producing high tibial osteotomy is indicated for the varus knee.
5. Varus-producing distal femoral osteotomy is indicated for the valgus knee.
6. Survivorship of TKA does not seem to be affected by previous osteotomy.
7. Cartilage reparative/restorative procedures are contraindicated in global knee arthritis.
8. The best results with cartilage reparative/restorative procedures are seen in knees with isolated femoral condyle lesions.
9. The unrevisable TKA is the most common indication for knee arthrodesis.
10. The position of knee arthrodesis should be 5° to 7° of valgus and 15° of flexion unless significant (≥2 cm) limb-length discrepancy is present.
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