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Complications of Genicular Nerve Blocks and Ablations

Kris Ferguson MD¹ and Hemant Kalia MD, MPH, FIPP, FACPM²

¹ Aspirus Hospital, Wausau, WI, USA
² Rochester Regional Health System, Rochester, NY, USA

Introduction

Knee pain is a common problem with a prevalence as high as 46.2% (32.2% in men and 58.0% in women). Degenerative joint disease is often the cause of pain in the knee [1]. The treatment for degenerative joint disease of the knee is often a total knee replacement. As of 2010, over 600 000 total knee arthroplasties (TKA) were being performed annually in the United States [2]. TKA consists of resection of the diseased articular surfaces of the knee followed by resurfacing with metal and polyethylene prosthetic components. While there are benefits to a TKA, there are also complications as well as a certain incidence of chronic pain. Complications of TKA include bleeding, post-surgical infection, thromboembolic disease, neural deficits, vascular injury, medial collateral ligament injury, malalignment, stiffness, deep joint infection, fracture, extensor mechanism disruption, patellofemoral dislocation, tibiofemoral dislocation, bearing surface wear, osteolysis, implant loosening, implant fracture/tibial dissociation, reoperation, revision, readmission, and death [3]. Despite a good outcome for many patients, approximately 20% of patients experience chronic pain after TKA [4]. Chronic pain after TKA can affect all dimensions of health-related quality of life, and is associated with functional imitations, pain-related distress, depression, poorer general health, and social isolation [4]. Geniculate ablations can help delay the need for a TKA, offer pain relief in patients not a candidate for TKA, and provide pain relief for persistent pain after a TKA.

Anatomy

The innervation of the knee is a web of nerves. There are branches from the tibial, common peroneal, femoral, and obturator nerves innervating the knee joint [5]. Nerves of relevance to the geniculate ablation are branches of the common peroneal and tibial nerves. The lateral superior geniculate nerve originates from the common peroneal division of the sciatic nerve 8–10 cm superior to the joint line [6]. The lateral superior geniculate nerve travels toward the superolateral aspect of the knee capsule deep to the biceps femoris muscle and the iliotibial band. The tibial nerve gives rise to three articular branches in the popliteal fossa, two of which are located on the medial aspect of the knee joint and are targets of the RF ablation: the medial superior and medial inferior geniculate nerves [6]. The lateral superior geniculate nerve and the medial superior and medial inferior geniculate nerves innervate the articular capsule of the knee joint [7]. These nerves are in close approximation to the lateral superior, medial superior, and medial inferior geniculate arteries. While the proximal anatomic course of the nerves is variable, all had a consistent distal contact on the femur and tibia [8]. Of note is Hilton’s law which states the nerve supplying the muscles extending directly across and acting at a given joint not only supplies the muscle, but also innervates the joint and the skin overlying the muscle [9–11].

Like the nerve supply to the knee joint, the arterial supply is a lattice with numerous anatomic variations. Relevant arterial vessels to the geniculate ablation are the: lateral superior genicular, medial superior genicular, and the inferior genicular arteries. These arteries also supply the patella. The medial superior genicular artery supplies the transverse suprapatellar portion of the peripatellar arterial ring. The lateral transverse patella arterial ring is partially supplied by the lateral superior genicular artery. The transverse infrapatellar portion receives partial perfusion from the medial inferior genicular artery [6].

The lateral superior artery arises proximal to the lateral condyle of the femur, deep to the tendon of the biceps femoris. It provides a superficial branch that supplies the vastus lateralis muscle and anastomoses with the lateral inferior genicular artery [6]. The lateral superior artery anastomoses with the descending branch of the lateral circumflex femoral artery [6]. The deep branch of the lateral superior genicular artery supplies the knee joint and anastomoses with the descending genicular and medial superior genicular arteries across the anterior aspect of the femur [6].

The medial superior genicular artery has two branches. One branch supplies the vasus medialis muscle and anastomoses with the descending genicular and medial inferior genicular arteries. The other branch supplies the knee joint and anastomoses with the lateral superior genicular artery [6].

The medial inferior genicular artery has two branches. The first courses along the upper border of the popliteus muscle. On the medial side of the knee, it anastomoses with the descending genicular and medial superior genicular arteries [6]. The second branch crosses the tibia under the patellar ligament to anastomose with the lateral inferior genicular and the anterior recurrent tibial arteries [6]. The medial inferior genicular artery is found in close proximity to the posterior horn of the medial meniscus [6].