A comparative study comparing area of extension of posterior knee capsule via posteromedial injection: a cadaveric study

• Published in: European journal of orthopaedic surgery & traumatology 2019-07, Vol.29 (5), p.1095-1100
• Main Authors: Tubtim, Chatnarong, Laupattarakasem, Pat, Laupattarakasem, Wiroon, Chaisiwamongkol, Kowit
• Format: Article
• Language: English
• Subjects: Arthroplasty, Replacement, Knee - adverse effects; Cadaver; Humans; Injections - adverse effects; Injections - methods; Joint replacement surgery; Joint surgery; Knee; Knee Joint - blood supply; Knee Joint - innervation; Knee Joint - surgery; Medicine; Medicine & Public Health; Models, Anatomic; Original Article • KNEE - ARTHROPLASTY; Pain; Pain, Postoperative - diagnosis; Pain, Postoperative - drug therapy; Peripheral Nerve Injuries - etiology; Peripheral Nerve Injuries - prevention & control; Surgical Orthopedics; Traumatic Surgery; Vascular System Injuries - etiology; Vascular System Injuries - prevention & control
• ISSN: 1633-8065; 1432-1068
• DOI: 10.1007/s00590-019-02399-2

Background 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. Purpose 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. Methods 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. Results 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. Conclusion 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.