Tubtim Chatnarong, Laupattarakasem Pat, Laupattarakasem Wiroon, Chaisiwamongkol Kowit
Department of Orthopedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
Bangkok Hospital Khon Kaen, Bangkok Dusit Medical Services, Khon Kaen, Thailand.
Eur J Orthop Surg Traumatol. 2019 Jul;29(5):1095-1100. doi: 10.1007/s00590-019-02399-2. Epub 2019 Feb 12.
Periarticular multimodal drug injection (PMDI) has gained popularity as common postoperative pain protocols in knee arthroplasty. PMDI sites can vary, but posterior capsule (PC) is a common injection site because of its abundance of pain nociceptors.
To prove the hypothesis whether posteromedial drug injection alone is sufficient to provide enough effect covering the PC in order to reduce risks of neurovascular injury. Secondary outcomes are to find proper volume of injection and safe zone for PMDI injection.
Ten fresh cadaveric knees were allocated into two equal groups, which differed in volume of dye injection: 25 ml and 50 ml. Dyes were injected into posteromedial capsule compartment, and the limbs were stored in a freezer for 2 weeks. Then the posterior compartment was carefully dissected to examine spreading of the dye solution.
No dye staining was seen superficially beneath subcutaneous tissue of the knees. In deeper layer, the dye mostly occupied medially along the fascia covering semimembranosus muscles. However, dispersion was limited distally by intermuscular septa and popliteal vessels. The 50-ml injection group provided wider extension in the superficial layer, but not in the deep layer.
The intermuscular septa and the fascia of popliteal vessels were shown to be the boundary between posteromedial and posterolateral compartments of the knee. Separate PMDI for both compartments is necessary to occupy the entire PC. We suggest that 1.5 cm lateral to lateral border of PCL insertion, just above popliteus tendon, is the safe zone for injecting PMDI into the posterolateral capsule.
关节周围多模式药物注射（PMDI）作为膝关节置换术后常见的疼痛处理方案已越来越受欢迎。PMDI的注射部位可能各不相同，但后关节囊（PC）因其富含疼痛感受器而成为常见的注射部位。
验证仅在内后侧进行药物注射是否足以覆盖PC并产生足够的效果，从而降低神经血管损伤的风险。次要目的是确定PMDI注射的合适剂量和安全区域。
将10个新鲜尸体膝关节平均分为两组，两组的染料注射量不同：25毫升和50毫升。将染料注射到内后侧关节囊腔，然后将肢体置于冰箱中保存2周。之后仔细解剖后关节腔，检查染料溶液的扩散情况。
在膝关节皮下组织表面未见染料染色。在更深层，染料主要沿覆盖半膜肌的筋膜向内侧分布。然而，其扩散在远端受肌间隔和腘血管限制。50毫升注射组在浅层的扩散范围更广，但在深层并非如此。
肌间隔和腘血管筋膜是膝关节内后侧和后外侧腔室的边界。为了覆盖整个PC，两个腔室都需要单独进行PMDI。我们建议，在PCL插入点外侧缘外侧1.5厘米处、恰好在腘肌腱上方，是将PMDI注射到后外侧关节囊的安全区域。
