**4.1 Lateral release**

In the lateral release procedure, a subcutaneous cavity from the AL portal up to the SL portal is needed. In cases of bipartite patella, careful probing to examine instability of the fragment, the status of articular cartilage underneath the patella, and the extent of the affected area to be treated is important. Viewing the lesion from inside the joint, firstly we pierce the lesion with 23-gauge needles at the proximal and distal edges of the lesion, to ensure the extent of release. It often involves not only the lateral retinaculum but also vastus lateralis muscle. We try to release only the attachment of the vastus lateralis muscle and lateral retinaculum to the fragment.

Basically the arthroscope is in the AL viewing portal. Under a magnified arthroscopic view, careful release should be performed, including the vastus lateralis muscle and lateral retinaculum, with a No. 11 blade through the SL portal. The release should be between the needle markers with a knife and arthroscopic scissor cutters. A 1-cm portal is sufficient to introduce both the lifter and an arthroscope, or the lifter and instruments, as the portal is stretched by the lifter. Authors prefer to debride the released edge of the vastus lateralis

Fig. 4. Operational field during surgery. A) The hanger lifts up the skin, affording the operator a view from outside the joint. B) Likewise, coil shaped lifter is creating the space.

In the lateral release procedure, a subcutaneous cavity from the AL portal up to the SL portal is needed. In cases of bipartite patella, careful probing to examine instability of the fragment, the status of articular cartilage underneath the patella, and the extent of the affected area to be treated is important. Viewing the lesion from inside the joint, firstly we pierce the lesion with 23-gauge needles at the proximal and distal edges of the lesion, to ensure the extent of release. It often involves not only the lateral retinaculum but also vastus lateralis muscle. We try to release only the attachment of the vastus lateralis muscle and

Basically the arthroscope is in the AL viewing portal. Under a magnified arthroscopic view, careful release should be performed, including the vastus lateralis muscle and lateral retinaculum, with a No. 11 blade through the SL portal. The release should be between the needle markers with a knife and arthroscopic scissor cutters. A 1-cm portal is sufficient to introduce both the lifter and an arthroscope, or the lifter and instruments, as the portal is stretched by the lifter. Authors prefer to debride the released edge of the vastus lateralis

Instruments (scissors) are introduced to the operative field. In these situations, the arthroscope is introduced from the AL portal and the hanger lifts the skin from the

superolateral portal.

**4.1 Lateral release** 

lateral retinaculum to the fragment.

muscle with a 4.5-mm shaver to create a gap between the muscle and fragment, which decreases the risk of the muscle scarring back down to the fragment (Fig.5).

Fig. 5. SL portal view. A 4.5 mm shavor is used in order to create a gap between muscle and fragment. VL, vastus lateralis muscle; P, patella.

It should ideally be done from outside the joint with care not to penetrate the joint, so that the joint capsule can be maintained intact to help minimize the postoperative leakage of the joint fluid.
