【Orthopedic Arthroscopy】Arthroscopic drilling in the treatment of osteochondritis dissecans

1. Definition

Osteochondritis dissecans (OCD) is a relatively common cause of knee pain and dysfunction in children, adolescents, and young adults.

OCD is an acquired underlying idiopathic reversible lesion of subchondral bone that presents with delamination and sequestration, with or without articular surface involvement and joint instability.

2. Anatomy

In the early stage, subchondral osteomalacia appears but the articular cartilage is completely covered, followed by cartilage separation and then osteochondral exfoliation.

3. Pathogenesis

The exact pathogenesis of OCD is still unclear, but it is generally believed to be related to the following factors, including repeated trauma, ischemia, inflammation, subcenter of ossification, and genetic factors.

In general, chronic repeated microtrauma may lead to microfractures, resulting in focal subchondral bone ischemia or altered growth patterns. Some patients are considered to have genetic, biochemical, and behavioral predispositions.

The name of osteochondritis dissecans suggests that inflammation is the cause of the disease, but research does not support inflammation as the primary cause.

Although Ribbing proposed as early as 1955 that OCD rarely presents with abnormal ossification, occasional findings of spontaneous healing of injuries to the lateral femoral condyle in young children suggest the presence of ossification variants.

Based on anatomical and pathological studies, Green and Banks proposed that ischemia is an intrinsic factor in OCD, but further studies failed to find a relative boundary of ischemia on the lateral surface of the medial femoral condyle, indicating that it is not the main pathogenic factor.

Mubarak and Carroll reported 12 cases of OCD over 4 generations, and Petrie found that 86 OCD patients had 1 first-degree relative. Despite a familial predisposition, it is generally believed that the most common OCD is not familial.

In 1933, Fairbanks believed that OCD may be caused by "internal rotation of the tibia, pushing against the medial condyle against the intercondylar ridge of the tibia". However, pure acute trauma and impingement of the anterior tibial ridge may not be the cause, as the most common injury site is the posterolateral aspect of the medial femoral condyle. OCD patients are more likely to be present in those involved in sports impacting and, therefore, support the etiology of repeated microtrauma.

4. Natural process

Crawfurd and colleagues followed up 21 patients whose damaged cartilage remained in situ without separation for an average of 7.5 years.

It was found that 3 out of 10 cases healed at the medial femoral condyle; 10 of the other 11 cases healed in other parts.

5. History and physical examination

Physical examination results are often subtle.

Children and adolescents with stable OCD may have a mildly painful gait.

When cartilage flaps or loose bodies appear in the later stage, typical biomechanical symptoms include interlocking, entrapment, trip wires, and soft legs.

With careful palpation at different degrees of flexion, the most painful point is often located above the anteromedial aspect of the knee. The pain area coincides with the lesion area and is usually located on the lateral aspect of the distal medial femoral condyle.

In stable cases, knee effusion, crepitus, and extreme pain within the normal range of motion are rare.

Wilson's sign may be helpful, but it is rare. Wilson test: The knee is flexed to 90°, the tibia is internally rotated, and then the knee is extended from 90° to full extension.

A positive Wilson test presents pain anterior to the medial femoral condyle, which is thought to be caused by the contact of the medial tibial crest with the lesion of the OCD.

Mechanical symptoms are often seen in children or adolescents with unstable injuries. Painful gait is common during joint movement, and knee effusion may be associated with crepitus.

In both stable and unstable OCD, both knees should be examined to determine if bilateral disease is present. If the pain persists for a long time, there may be atrophy of the quadriceps on the affected side.

6. Imaging and other diagnostic tests

Imaging studies documenting the various successful outcomes of non-surgical treatments have been closely watched in literature reviews. The purpose is to judge the characteristics of the lesions, determine the prognosis of non-surgical treatment, and observe the healing of the lesions.

The first choice for imaging examination is plain X-ray, including anteroposterior (AP), lateral and tunnel views

The tunnel position is particularly valuable because typical OCD lesions are located on the flexion surface of the lateral aspect of the medial femoral condyle.

The Merchant view should be included to better visualize OCD lesions of the patella or trochlea.

Plain X-rays usually confirm the nature and location of the injury and exclude other skeletal pathological changes in the knee joint.

MRI is most valuable for determining the size of the lesion and the status of the cartilage and subchondral bone.

On early MRI, the extent of bone edema, hyperintense areas beneath the fracture fragments, and loose bodies are also important findings.

Although not commonly used, technetium bone scans are also used to provide information on the biological potential of OCD healing.

7. Differential diagnosis

irregular ossification

acute osteochondral fracture

Meniscus damage

8. Non-surgical treatment

Initial non-surgical treatment is for intact lesions in skeletally immature children.

The ideal non-surgical treatment is still controversial. Clinicians believe that the subchondral bone is the main source of the disease and treatment should be fixed for a period of time. And clinicians who believe that articular cartilage is the root cause of the disease tend to stay active.

Immobilization includes casts, braces, and standard knee immobilization.

The author recommends that the non-surgical treatment of OCD injury be divided into three stages.

Phase 1

1 to 6 weeks

Knee hinged brace brakes allow the patient to walk with the brace locked in extension. Can unlock joint activities 5 times a day, 5 minutes at a time.

Phase 2

6 to 12 weeks

If the patient is pain-free, radiographs show signs of healing after 6 weeks, weight bearing can be allowed to begin without immobilization, and physical therapy can be initiated to improve knee range of motion and quadriceps and hamstring strength.

Stage 3

This phase can be initiated if the patient continues to be pain-free, with radiographic evidence of healing.

Typically this phase begins 3 months after treatment. Running, jumping and emergency stops are possible under close observation.

High stress and activities that may cause shear stress in the knee should be limited until the child is pain-free for several months and until plain radiographs show that the injury has healed. Until the child has been pain-free for several months and the X-ray shows a healed lesion.

The goal of nonoperative treatment is to promote subchondral bone healing and to prevent potential cartilage collapse, secondary fractures, and crater degeneration.

9. Surgery

It is generally accepted that surgical treatment should be considered for unstable or dissociating lesions that remain uncured after reasonable non-surgical treatment, especially those with skeletal maturation.

Surgical treatment is recommended in the following cases: juvenile cases with persistent symptoms, presence of symptomatic loose bodies, epiphysis closure or bone fragment separation expected within 1 year.

The purpose of surgical treatment is to promote subchondral bone healing, maintain joint integrity, fix unstable bone fragments, and transplant chondrocytes to repair the defect.

Surgical treatment is selected to provide stable subchondral bone structure, calcified tide lines, and cartilage with viability and biomechanical properties equivalent to or similar to hyaline cartilage.

preoperative planning

Careful preoperative evaluation and preparation are prerequisites for successful surgery.

All imaging data should be reviewed before surgery. If the bony part of the avulsion fragment is relatively large, plain radiographs usually reveal the lesion. But X-ray films cannot show the actual size of the cartilage slices. The extent of cartilage damage can be determined by MRI to determine the extent of the lesion. Any other lesions shown on imaging should also be addressed.

Perform a thorough physical examination under anesthesia.

body position

For arthroscopic surgery, position is largely a matter of surgeon preference. Many asanas can be used.

The leg is placed on the lower limb barrier, and the knee joint is over the caudal side of the operating table, so that the knee joint can be flexed 90° and the calf can hang freely.

Lie supine on the operating table with your thighs flexed and knees 90°. The knee joint can be flexed, in which case the lower leg can hang freely over the side of the operating table.

approach

Use a standard arthroscopic parapatellar approach.

If the lesion is too large or in an atypical location, an auxiliary approach can be established slightly above or below the standard parapatellar approach.

Drilling through the articular surface can be used for complete 2.0 injuries, and is especially valuable when the injury is dislodged, partially dislodged, or unstable).

For complete injuries, epiphyseal drilling can be used

Arthroscopic drilling for complete OCD injury

A tourniquet on the knee joint.

The anterolateral approach serves as the observation approach, and the anteromedial approach serves as the operator approach.

Perform a complete arthroscopic knee examination. Record and manage other pathologies of the knee joint.

Drilling through the articular surface

Confirm damage

A 0.62in (1.57cm) Kirschner wire is placed vertically to the site of the injury, and its approach depends on the location of the defect.

The key to the surgery is to keep the Kirschner wire as vertical as possible. With knee flexion and extension, additional access is established to achieve the desired position.

Under arthroscopic surveillance, drilling was performed.

The proper penetration depth is determined by the blood or fat flowing out of the pores.

In immature patients, drilling should pass through the calcified tide line, taking care not to penetrate the bone marrow.

Epiphyseal drilling

After the examination was completed, a 0.62in (1.57cm) K-wire was arthroscopically pointed at the lesion in a proximal-to-distal direction using a guide. Guides help maintain the proper angle.

The origin of the Kirschner wire is from the distal end to the epiphysis to avoid any damage.

The Kirschner wire penetrates slowly into the subchondral bone, taking care not to penetrate the articular cartilage.

The Kirschner wire is kept as perpendicular to the lesion as possible.

The position and depth of the K-wires were confirmed arthroscopically.

The Kirschner wire penetrates a few millimeters of the lesion.

K-wires and instruments are removed and the knee joint is re-examined.

The knee joint was sutured, covered with a sterile dressing, and then a knee immobilizer was used.

Arthroscopic drilling in the treatment of torn OCD injury

Assess the entire lesion and prepare the tissue bed. Remove all granulation tissue and subchondral sclerotic bone until the subchondral bone is reached.

For deeper lesions, autologous or allogeneic cancellous bone grafts can be used to ensure that the torn lesion repairs no lower than the unaffected knee cartilage.

Lesion reduction is fixed with various implants, such as cannulated screws and Herbert screws. The immobilization device can be metal or bioabsorbable material. Implant use depends on the operator.

The author prefers the use of small, bioabsorbable, double-threaded compression screws for the treatment of torn lesions that require adequate subchondral bone support

Once the lesion is firmly fixed, drilling can be performed to enhance healing.

Arthroscopic drilling for unstable lesions

Inspect the knee joint and remove any loose bone fragments if necessary.

Examine the diseased bone bed and remove any granulation tissue and sclerotic bone.

For reversible lesions, trim the margins and fix the lesion to the bone bed. A variety of implants can be used to fix the lesion depending on the operator's preference.

Examine the knee joint before closing the incision.

The arthroscopic instruments were removed and the arthroscopic approach was closed.

Place the dumpling chain knee brace.

Key points and error prevention

surgical technique

Read the imaging data again before surgery to fully assess the lesion

Drilling through the articular surface

The Kirschner wire is as vertical as possible to the articular surface to avoid peeling or falling off of the lesion, and is only suitable for complete lesions

Postoperative treatment

For patients with intact lesions:

The author uses a hinged knee brace with mild flexion and extension for 4 to 6 weeks.

The patient was allowed to bear partial weight (week 1) and then fully bear with the brace locked in the extended position.

Compression is allowed to stimulate healing while high-intensity running and jumping activities are avoided.

After the dumpling chain brace is removed, the patient can undergo physical therapy, joint range of motion and muscle strength training.

Between 6 and 12 weeks, patients were restricted from running and jumping.

Review after 3 months (anteroposterior, lateral, intercondylar concave and tunnel).

Complete healing was observed in patients with intact lesions. If the lesion does not heal completely, exercise restriction for 2 to 3 months until complete healing.

For patients with full-thickness lesions:

For patients with full-thickness lesions postoperatively, use continuous passive motion (CPM) to accelerate articular surface healing. The author prefers to use CPM 6 weeks after surgery.

CPM can promote the healing of small lesions (>3mm in diameter) in rabbit articular cartilage. Rodrigo and colleagues found similar results in human lesions of 1 to 2 cm; they reported improved clinical outcomes using CPM 6 hours a day for up to 8 weeks.

Regardless of the treatment chosen, patients should have a rehabilitation program that combines protection of damaged articular surfaces and subchondral bone with preservation of muscle strength and range of motion.

Straight leg raises and isometric exercises can be performed after surgery or during the immobilization period. In general, straight leg raises start with no resistance and gradually increase the weight by 2 to 3 pounds (0.91 to 1.36 kg) per week, or tolerable weight, until 10% of the patient's body weight is reached.

Develop a 6 to 8-week home or formal physical therapy plan that includes range of motion, extension, progressive strength and function, or physical training.

Closed-chain training begins at week 6. During this time, the patient was prohibited from running and jumping but allowed low-intensity activities such as walking, cycling, swimming, and activities of daily living.

Patients with full-thickness disease should limit high-intensity activities until 6 months after surgery.

If patients resume activities before the cartilage becomes firm, they often complain of pain when doing exercises such as squat jumps.

Result

For patients with small stable defects and skeletal immaturity, conservative treatment is the first choice, and typical nonoperative treatment usually lasts 3 to 6 months, with many authors reporting success rates of 50% to 94%.

Non-surgical treatment is effective in patients with skeletal immature wide open epiphysis and no signs of instability on MRI.

Bradley and Dandy retrospectively analyzed 11 knee joints in 10 children, treated with arthroscopic drilling, and found that 9 knee joints healed 12 months after surgery.

Aglietti and collaborators retrospectively studied 16 knee joints of 14 patients after 1 year of conservative treatment, using arthroscopic drilling, and found that all patients gradually healed after treatment.

Kocher and collaborators retrospectively analyzed 30 knee joints from 23 patients who underwent arthroscopic drilling after 6 months of conservative treatment. All patients who failed non-surgical treatment experienced healing after drilling.

Complication

Potential barriers to healing, especially in older adolescents treated nonoperatively. Patients with skeletal maturity have a worse prognosis. Surgery should be performed to promote healing in these patients with non-surgical treatment without healing and with larger defects approaching skeletal maturity.