Cartilage defects of the knee joint surface are more common in young and middle-aged patients and are more difficult to treat, and there is no uniform method for the repair and treatment of cartilage defects. Arthroscopic surgery can not only improve the diagnosis rate of cartilage injury, but also treat cartilage defects with minimally invasive surgery. In our hospital, we carried out arthroscopic autologous mosaic osteochondral transplantation for the treatment of cartilage defects in the knee joint from June 2004 to December 2010, and the clinical results were satisfactory.
1. Data and methods
1.1 General information
There were 60 patients in this group, 42 males and 18 females, aged 21-50 years old, average 36 years old. 39 cases had a clear history of trauma, and the main clinical manifestations were knee swelling and pain, which increased after activity, especially when walking under weight. 7 cases had knee popping. All of them had different degrees of knee swelling and fluid accumulation and quadriceps atrophy. 12 of them had blood accumulation in the knee joint.
The Brittberg-Peterson functional score was used: it included 13 aspects of rest pain, activity pain, joint strangulation, claudication, degree of joint swelling, difficulty walking, difficulty running, difficulty squatting, difficulty climbing stairs, joint pain, joint stiffness, knee flexion pain, and joint instability. Each item is scored 0-10, with 0 indicating no symptoms and 10 indicating severe symptoms. The total score was 0-130. The mean score was (87.63±8.19).
1.2 Arthroscopy
All patients in this group underwent arthroscopic examination, and the degree of cartilage injury was classified according to Johnson-Nurse: type I: total cartilage separation subchondral bone exposed; type II non-total cartilage separation, part of the cartilage floating like a ping-pong ball, subchondral bone not exposed. 60 patients, including 39 cases of type I, 21 cases of type II, 33 cases of weight-bearing surface defect of the femoral inner condyle, 27 cases of weight-bearing surface defect of the femoral outer condyle. The extent of the lesion: 10-40 mm. 12 cases were associated with meniscal injury and 3 cases were associated with cruciate ligament injury.
1.3 Surgical method
After routine arthroscopic examination, the damaged lesions were cleaned and repaired, and the extent of cartilage defects was clarified. The diseased cartilage and subchondral bone were removed under direct arthroscopic view to normal bone tissue, and the base of the lesion was flattened. Depending on the size of the defect, a 6-8 mm diameter hollow drill was used to drill the holes at an interval of 1-2 mm, perpendicular to the articular surface and parallel to each other, for traumatic cartilage defects of younger age, the graft hole was cut 15 mm deep, and for osteoarthritis, 20 mm deep. normal cartilage from the non-weight-bearing area at the edge of the femoral condyle was selected, and a bone cartilage block of the same size as the recipient area was drilled and placed in wet saline gauze.
The donor bone hole was filled with the corresponding bone block from the recipient area, and the gap could be closed with bioprotein gel. Place the osteochondral bone block into the corresponding size of the graft peg propeller, and push the bone block slowly and evenly into the corresponding size of the bone hole in the recipient area. After placing all the grafted bone blocks, the grafted bone blocks can be gently tapped with a flat-tipped stick to make the grafted bone blocks in the recipient area blend into the same arc with the joint surface and maintain the same curvature of the joint surface.
1.4 Postoperative rehabilitation
After surgery, the affected limb should be wrapped with elastic bandage, and on the first day after surgery, the patient should be encouraged to practice straight leg elevation, and on the third day after surgery, the CPM machine should be used for functional exercises. At 6 weeks after surgery, the knee could be partially weight-bearing with the help of crutches, and at 12 weeks, the knee function was basically normalized and the knee was walking on the ground normally.
2. Results
All 60 patients in this group were followed up for 12-36 months, with an average of 25 months. The MRI of the knee joint was reviewed 1-2 years after surgery, and the cartilage surface of the cartilage defect area was basically flat, and the grafted osteochondral column grew well. Postoperative Brittberg-Peterson score below 20 was considered as cure, 20-40 as effective and >40 as ineffective. In our group, 54 patients had a score of 0 at 3 months after surgery, 4 cases had a score of 4 due to slight pain when going up and down stairs, and 2 cases had a score of 2. The cure rate was 100%, and there was a statistically significant difference (P<0.01) in the preoperative and postoperative statistics using paired measures t-test.
3. Discussion
In recent years, articular cartilage defects caused by trauma and various diseases (such as osteoarthritis, exfoliative osteochondritis, osteonecrosis, etc.) are very common and more difficult to manage. Normal articular cartilage is mainly composed of chondrocytes and cellular matrix, lacking direct blood, lymphatic fluid and nerve supply, and mature chondrocytes cannot undergo mitosis, so articular cartilage has poor self-repair ability, and cartilage defects or injuries are difficult to repair.
Traditional treatments for articular cartilage defects include cleaning and drilling, microfracture, and arthroplasty, but instead of hyaline cartilage, they induce the generation of fibrocartilage with poor wear resistance, whose biomechanical and mechanical properties are much lower than those of hyaline cartilage and cannot prevent degenerative changes in articular cartilage, with poor long-term efficacy. Autologous osteochondral grafts are not suitable for the repair of major joints due to the limited source of donor and the difficulty of fixation, and the mechanical properties and long-term tolerability of the new tissue are not clear. Allogeneic cartilage grafting can treat large cartilage defects, but there are immune rejection, disease transmission, subchondral bone collapse, joint instability, and graft cartilage resorption, etc. The early and mid-term results are still satisfactory, but there are different degrees of degeneration in the long term.
Autologous onlay osteochondral grafting is an arthroscopic procedure in which bone is taken from the cartilage surface of the non-weight-bearing area and grafted to the cartilage defect to fill the defective area and restore the flexion of the joint surface. The purpose is to fuse the subchondral cancellous bone of the donor and the recipient area after transplantation to provide the necessary blood supply for the transplanted cartilage as soon as possible. Due to the presence of subchondral bone, the transplanted cartilage block is embedded in the bone cavity of the recipient area to obtain reliable fixation without collapse. The surgery has the following advantages.
a. Reduction of disease transmission through autologous tissue grafting.
b. The grafted cartilage is simple to obtain, the bone block is stable, and the subchondral bone has sufficient strength to maintain the integrity of the articular cartilage without internal fixation, avoiding secondary surgery.
c. The graft has sufficient length to be embedded with the recipient area, and it is not easy to become a free body in the early stage of the graft.
d. Arthroscopic operation is less traumatic, facilitates early functional exercise and rehabilitation, prevents joint adhesions, and conforms to the minimally invasive cosmetic viewpoint.
Autologous inlay osteochondral grafting is suitable for patients with limited cartilage defects, generally under the age of 50. Joint lesions such as anterior and posterior cruciate ligaments, medial and lateral collateral ligaments, and meniscal injuries must be treated before cartilage transplantation. X-ray and MRI must be perfected before surgery to fully estimate the surgical approach and the conditions that may be encountered intraoperatively. Intraoperative attention should be given to.
a. Revision of the recipient area, complete removal of diseased articular cartilage with radiofrequency plasma knife and planer, edge up to normal cartilage. When taking the osteochondral block and bone graft bed, it is necessary to make the holes drilled in the osteochondral block and bone graft bed perpendicular, so as to avoid cross drilling to make the bone block unshaped.
b. The size of the graft should be 15-20 mm long and 6-8 mm in diameter, too thin is easy to fracture and make the operation more difficult, too thick is easy to cause complications in the donor area.
c. The implanted osteochondral block should be adjusted to the same curvature as the femoral condylar surface, which is the key to ensure the flatness of the cartilage surface in the recipient area.
d. After successful transplantation, a 1-1.5 mm diameter Kirschner needle can be used to drill holes in the graft gap to cause microfractures, which is more convenient for the growth and healing between the grafts.
e. The donor area cartilage should be normal, without softening, hyperplasia and other lesions. Patients with defect area <3 cm2 can prefer the donor area of the medial and lateral talus, and patients with defect >4 cm2 can choose the donor area above the posterior aspect of the medial femoral condyle, which is in contact with the posterior part of the meniscus only when the knee is hyperflexed and has low compressive stress, which can reduce the complications of the donor area and increase the range of donor area selection.
The study proved that autologous mosaic osteochondral transplantation for knee cartilage defects obtained good clinical results, and we used this method to repair cartilage defects on the articular surface of the femoral condyle in 60 cases with good postoperative results, little trauma, few complications, and low cost, which is a reliable method to repair limited osteochondral defects and restore the integrity of the articular surface.