c. **Ultrasound-guided Hamstring block** [50, 51]**: (Figure 12)**


*Regional Analgesia for Knee Surgeries: Thinking beyond Borders DOI: http://dx.doi.org/10.5772/intechopen.99282*

#### **Figure 12.**

*Hamsting block injection sites.*

*I: First injection under the sartorius muscle in the adductor canal. II: Second injection below gracilis muscle. III & IV: Third and fourth injections around semotendinosus muscle. (SM: Sartorius muscle, VMM: Vastus medialis muscle, AMM: Adductor magnus muscle, RFM: Rectus femoris muscle, VIM: Vastus intermedialis muscle, VLM: Vastus lateralis muscle, BFM: Bicep femoris muscle, STM: Semitendinosus muscle, SMM: Semimembranosus muscle, GRM: Gracilis muscle, SN: Saphenous nerve, NVM: Nerve to vastus medialis, SCN: Sciatic nerve, Yellow color: Nerves, Red color: Artery, Blue color: Vein, Brown color: Muscles, Gray color: Femoral bone, Light blue area: Drug spread).*

	- i. 5–7 ml below the sartorius in the adductor canal
	- ii. 10–15 ml below gracilis muscle with probe over the posteromedial aspect of the distal thigh
	- iii. 15–20 ml around the semitendinosus muscle (above and below) with probe over the posterior aspect of the distal thigh

#### III.**Infiltration techniques**:

#### a. **I-PACK Block**:

The term i-PACK is described as a motor-sparing RA technique that consists of an infiltration of local anesthetic into the interspace between the popliteal artery and the posterior capsule of the knee [52–54]. It can be used as an adjunct to the femoral nerve or adductor canal blocks to cover the posterior knee pain. It creates field block (**Figure 13**), causing blockade of articular branches arising of the tibial, common peroneal, and obturator nerves in the popliteal region. Indications of I-PACK include postop analgesia for TKR surgeries, ACL repairs, and procedures involving the posterior aspect of the knee. The required LA volume for this block is 15–20 ml. This block needs to be given preoperatively due to loss of anatomical landmarks after surgery. It can be given using two approaches: medial approach and popliteal approach, as shown in **Figure 14**.

**Figure 13.** *Needle track and drug spread of i-PACK block. (PA: Popliteal artery, SCN: Sciatic nerve, Blue color: Needle track and drug spread between PA and femur).*
