Arthroscopic Treatment of OCD of the Capitellum

Sterile Instruments/Equipment

30-degree arthroscope

2.7-mm arthroscope for working in direct lateral compartment

4.0-mm arthroscope for routine anterior and posterior compartments; inflow is from cannula of the arthroscope, and, because it is larger, it allows better inflow, joint distension, and hemostasis

Self-locking limb positioner (eg, Arthrex Trimano, Smith & Nephew SPIDER) 2.9-mm full-radius shaver blade without teeth

Microcurettes

Allows better movement in tight lateral compartment Small joint obturator and cannulas

Small slotted cannula

5.5-mm disposable cannula with stop cock Microfracture awls

Smooth .062-in Kirschner wire Sterile tourniquet

1.6- and 2.0-mm smooth drills

1.6- or 2.0-mm absorbable nails for osteochondritis dissecans (OCD) fixation (1.6 mm most commonly used)

Positioning

Figure 21-1 Prone positioning with self-locking limb positioner improves working space in smaller patients.

Lateral decubitus for patients over 150 lb (Fig. 21-2)

Figure 21-2 Lateral decubitus positioning preferred for larger patients or those with difficult airways.

Self-locking limb positioner allows control of arm within tight space between elbow and table.

Surgical Approach

Diagnostic arthroscopy is done with anteromedial, anterolateral, posterior, and posterolateral portals.

Direct lateral and accessory lateral portals are created specifically for management of OCD lesions of capitellum.

An inflow pump system allows better visualization while working with 2.7-mm arthroscope in the lateral compartment.

To obtain adequate fluid pressure, pump pressure can be increased to 90-100 mm Hg to offset the small diameter of the 2.7-mm arthroscope.

OCD fragment are identified, and the competency of the overlying cartilage is evaluated.

Although uncommon, fragments over 1 cm in diameter and with sufficient underlying bone may be suitable for fixation.

Small, multifragmented, and/or inadequate underlying bone should be removed.

Typically there is loose, unstable cartilage overlying the lesion, which is easily recognized arthroscopically.

However, lesions with intact overlying articular cartilage but unstable underlying bone require careful probing to identify soft, ballotable articular cartilage indicating location of the lesion.

For grade I or II chondral lesions, in situ drilling with a .062-in smooth Kirschne wire should be considered.

Debridement/Microfracture

This is recommended for OCD fragments that are not suitable for fixation (mos grade III and IV elbow OCD lesions).

Unstable cartilage flaps are removed with a shaver and curettes (Fig. 21-3).

Figure 21-3 Loose, unstable cartilage overlying capitellar OCD. Most lesions are easily identifiable arthroscopically, but some require careful use of a probe to localize the defect.

The base of the OCD lesion is debrided of overlying fibrous tissue (Fig. 21-4).

Care is taken to avoid removing excess subchondral bone.

Loose or unstable cartilage edges that can propagate into loose bodies or chondral flaps should be removed.

Figure 21-4 Fibrous tissue under OCD fragment should be debrided with a curette and/or shaver.

After a healthy bone base is obtained, microfracture of the capitellum is done to promote fibrocartilage healing (Fig. 21-5).

Microfracture awls usually are adequate for bone marrow stimulation. Chronic, avascular lesions may require the use of a .062-in Kirschner wire for deeper drilling.

Drilling is performed perpendicular to the cartilage surface to avoid chondral penetration. This may require additional incisions or skin punctures to obtain correct trajectory.

Figure 21-5 Microfracture of the base of the lesion to stimulate fibrocartilage healing.

OCD Fixation

If the OCD fragment appears suitable for fixation, templating is recommended before surgery (Fig. 21-6).

The length of the proposed nail/fixation device is templated on MRI images. The maximal length of the nail is used for fixation while avoiding the opposite cortex or physis.

The number of nails that will fit within the OCD fragment is estimated (ideally 2).

Figure 21-6 Template of proposed OCD fixation.

The recipient capitellar lesion is prepared with microcurettes and a 2.9-mm full-radius shaver without teeth (Fig. 21-7).

The surrounding border of articular cartilage should be smooth and stable.

It is helpful to microfracture the base of the lesion to assist with healing after fixation (Fig. 21-8).

Figure 21-7 OCD lesion is opened to reveal fibrous tissue overlying base.

Figure 21-8 Base of recipient lesion is debrided and prepared with microfracture to improve healing potential. Note that the OCD lesion remains hinged to the base (arrow) to allow easier reduction.

The recipient lesion often needs to be deepened and enlarged to allow the OCD fragment to be fully seated and avoid difficulty with reduction.

If possible, the defect should be left hinged to the surrounding cartilage because complete detachment will increase the difficulty of reduction and fixation (Fig. 21-9).

Figure 21-9 Hinged OCD lesion beneath probe remains attached to remaining articular cartilage to prevent difficult reduction of a detached fragment.

A 1.5-in 25-gauge needle is used to identify percutaneous placement of fixation nails perpendicular to the joint surfaces

A small stab wound is made with a no. 11 blade scalpel, and a drill or insertion cannula with impactor is placed percutaneously against the OCD lesion.

A nail length is selected that will place fixation barbs well within the capitellum and past the base of the lesion while avoiding open physes.

Often the physis will be penetrated to afford adequate strength of fixation.

Smooth, nonthreaded, bioabsorbable nails generally do not result in growth arrest.

When using nails, we recommend overdrilling with a 2.0-mm drill for a 1.6-mm nail, unless the underlyling bone is atypically osteoporotic.

This avoids difficulty when inserting the nail.

A skilled assistant is necessary when inserting nails to manage the arthroscope and inflow.

The guide for a 1.6-mm nail is placed over the fragment (Fig. 21-10).

If the fragment remains proud, it is tapped gently with the guide and inserter to further reduce the fragment.

Repetitive or aggressive impaction of the fragment should be avoided to prevent chondrocyte damage.

If the fragment cannot be fully reduced, the guide is removed and the recipient lesion is prepared further.

Figure 21-10 Guide is placed perpendicular to reduced articular cartilage surface. Percutaneous placement of the guide may be required to obtain correct trajectory.

Once the lesion is appropriately reduced with the guide in place, inflow is turned

off.

The backflow of fluid can displace the nail out of the guide during insertion.

The nail is placed carefully in the guide to avoid the nail being washed out of the inserter (Fig. 21-11).

A small needle driver is used to place the nail in the end of the inserter and is covered with a finger (Fig. 21-12).

Figure 21-11 Example of an arthroscopic OCD fixation system.

Figure 21-12 After placement of fixation nail into the device, the surgeon)s finger should be held over the opening to prevent backing out of the nail due to backflow through slots in the guide.

The finger is replaced with the impactor, and the nail is pushed until its tip is positioned in the slot of the guide (Fig. 21-13).

Figure 21-13 The surgeon)s finger is carefully replaced with impactor to prevent the nail from backing out of the guide.

The inflow is turned on to observe nail insertion through the open slot in insertion guide (Fig. 21-14).

Figure 21-14 Fixation nail (shown in inset) is visualized through slot in guide to ensure proper insertion (barbs of transparent nail noted with arrow).

The nail is tapped into the fragment until the head of the nail is flush with the articular cartilage (Fig. 21-15).

Figure 21-15 The nail is impacted into the lesion with care to avoid fragmentation or loss of reduction.

After the nail is seated with the 1.6-mm impactor, a 2.0-mm impactor can be used to further seat the head of the nail at or slightly below the level of surrounding articular cartilage (Fig. 21-16).

Figure 21-16 The nail should be slightly countersunk to the articular surface after insertion.

These steps are repeated for each additional nail.

Most lesions will have space for only one or two nails.

The OCD lesion should be level with, if not countersunk to, intact articula cartilage.