The anterior branch of the medial femoral cutaneous nerve innervates the anterior knee: a randomized volunteer trial

A cadaveric study of the innervation of the anterior compartment of the knee

PURPOSE

Anterior knee pain can significantly affect the quality of life of those living with it. One approach to addressing anterior knee pain involves the selective denervation of the patella to reduce afferent pain transmission, but there has been no consensus on the number, location, or origin of the nerves innervating the patella. In this study, we review existing literature on anterior knee innervation and present findings from our cadaveric dissection to provide a detailed description of the innervation of the anterior knee joint.

MATERIALS AND METHODS

Two independent authors reviewed the literature on anterior knee innervation from PubMed and Embase, and a sub-search was conducted on the relationship between the infrapatellar branch of the saphenous nerve (IPBSN) and the anterior knee compartment. Subsequently, two fresh-frozen cadavers were dissected to determine whether the saphenous nerve innervates the anterior knee compartment and to confirm, through tissue biopsies stained with laminin and beta-III-tubulin, whether previously described nerves innervate the patella.

RESULTS

A total of 463 and 304 entries on patellar innervation and saphenous nerve anatomy, respectively, were identified through PubMed and Embase. Descriptions of the nerves innervating the patella were found to be inconsistent and are summarized. No studies identified branches of the IPBSN directly innervating the patella or patellar tendon. On cadaveric dissection, we found that anterior knee innervation comprised the nerves within the distal vastus medialis and lateralis muscles, the medial and lateral retinacular nerves, and occasionally a branch of the IPBSN that innervated the inferomedial anterior knee skin.

CONCLUSIONS

This study is the first to provide histological confirmation of patellar innervation by the IPBSN. Our findings suggest that an approach based on a positive response to differential nerve blocks, followed by resection of the nerves implicated in that anterior compartment knee pain, may be more effective in treating persistent anterior knee pain than circumferential electroablation of the patella or routine resection of the IPBSN.

LEVEL OF EVIDENCE

Level III.

Different peripheral nerve blocks for patients undergoing total knee arthroplasty: a network meta-analysis of randomized controlled trials

INTRODUCTION

To comprehensively compare the effect of different peripheral nerve blocks for patients undergoing total knee arthroplasty (TKA).

MATERIALS AND METHODS

PubMed, Embase, Cochrane Library, and Web of Science were comprehensively searched. The outcomes included postoperative pain, postoperative function, adverse events, oral morphine equivalent (OME), and perioperative indicators. Network plots, forest plots, league tables and rank probabilities were drawn for all outcomes.

RESULTS

Totally 30 studies were included. For postoperative pain, continuous adductor canal block (cACB) + genicular nerve block (GNB) was most likely to be the most effective block regarding rest pain score at 24 h; cACB + GNB was most likely to result in the lowest rest pain score at 48 h; patients undergoing cACB + infiltration between the popliteal artery and the capsule of the knee (IPACK) + GNB was most likely to have the lowest motion pain score at 24 h; patients undergoing cACB + GNB was most likely to have the lowest motion pain score at 48 h. For postoperative function, patients undergoing cACB + IPACK + GNB had the highest likelihood to exhibit the shortest time in Timed Up and Go test (TUG); cACB + tibial nerve block (TNB) was most likely to be the most effective block in terms of range of motion (ROM); cACB + IPACK was most likely to be the optimal block concerning the ambulation distance.

CONCLUSION

cACB combined with IPACK/GNB may be the most favorable block after TKA, continuous blocks may be better than single-shot blocks, and combined blocks may be better than separate blocks.

Distal subsartorial compartment block of the saphenous nerve - A dissection study and a patient case series

STUDY OBJECTIVE

A saphenous nerve block is an important tool for analgesia after foot and ankle surgery. The conventional midthigh approach to saphenous nerve block in the femoral triangle may impede ambulation by impairing quadriceps motor function.

PRIMARY OBJECTIVE

Developing a selective saphenous nerve block targeting the nerve distal to its emergence from the adductor canal in the subsartorial compartment.

DESIGN

This study consists of A) a dissection study and B) Data from a clinical case series.

SETTING

A) Medical University of Innsbruck, Austria (dissection of 15 cadaver sides) and. B) Aarhus University Hospital, Denmark (5 patients).

INTERVENTIONS

A) Five mL of methylene blue was injected into the subsartorial compartment distal to the intersection of the saphenous nerve and the tendon of the adductor magnus guided by ultrasound. B) Five patients undergoing major hindfoot and ankle surgery had a subsartorial compartment block with 10 mL of local anesthetic in addition to a popliteal sciatic nerve block.

MEASUREMENT

A) The frequencies of staining the saphenous and medial vastus nerves. B) Assessment of postoperative pain by NRS score (0-10) and success rate of saphenous nerve block by presence of cutaneous anesthesia in the anteromedial lower leg, and motor impairment by ability to ambulate.

MAIN RESULTS

A) The saphenous nerve was stained in 15/15 cadaver sides. A terminal branch of the medial vastus nerve was stained in 2/15 cadaver sides. B) All patients were fully able to ambulate without support. No patients had any post-surgical pain from the anteromedial aspect of the ankle and foot (NRS score 0). The success rate of saphenous nerve block was 100%.

CONCLUSION

The saphenous nerve can be targeted in the subsartorial compartment distal to the intersection of the nerve and the tendon of the adductor magnus. The subsartorial compartment block provided efficient analgesia without quadriceps motor impairment.