Functional Anatomy of the Hip - Neural and Vascular

Original Editor - Rishika Babburu

Top Contributors - Rishika Babburu, Ewa Jaraczewska and Kim Jackson  

Introduction

The hip joint is a synovial joint with articulation between the femoral head and the acetabulum of the pelvis. The rounded femoral head sits within the cup-shaped acetabulum of the pelvis.

Sciatic Nerve

Nerve Supply

Hilton's law states “The same trunks of nerves, whose branches supply the groups of muscles moving a joint, furnish also a distribution of nerves to the skin over the insertions of the same muscles; and – what at this moment more especially merits our attention – the interior of the joint receives its nerves from the same source.” A joint tends to be innervated by a branch of a motor nerve which also supplies a muscle extending and acting across the joint, another branch of the nerve often supplies the overlying skin.

• The obturator nerve is considered the primary source of innervation to the hip.

Femoral Nerve

• Branches of the femoral and sciatic nerves contribute to its sensory innervation.

• The hip joint receives multiple innervations primarily involving the hip capsule.
• The posterior articular nerve, a branch of the nerve to the quadratus femoris provides the most extensive nerve supply to the hip joint, including the posterior and inferior regions of the capsule and the ischiofemoral ligament.
• Superiorly, the hip capsule is innervated by the superior gluteal nerve.
• Anterior innervation of the capsule is provided by direct branches of the femoral nerve.
• The anteromedial and anteroinferior regions are supplied by the medial articular nerve, which arises from the anterior division of the obturator nerve.
• The ligamentum teres is innervated by the posterior branch of the obturator nerve .
• Acetabular labrum consists of sensory nerve end organs and ramified free nerve endings, suggesting that the labrum may provide nociceptive and proprioceptive feedback to and from the hip joint

Femoral artery

Arterial Supply

Arterial supply of the hip joint is by the cruciate and trochanteric anastomoses supply. A branch from the posterior branch of the obturator artery may also be present in the ligamentum teres.

Cruciate anastomosis

• Transverse branch of medial circumflex femoral artery
• Transverse branch of lateral circumflex femoral artery
• Ascending branch of first perforator artery from profunda femoris artery
• Descending branch of an inferior gluteal artery
• Obturator artery.

Trochanteric anastomosis

• Descending branch of a superior gluteal artery
• Ascending branch of medial circumflex femoral artery
• Ascending branch of lateral circumflex femoral artery
• Inferior gluteal artery

Clinical Importance

Avascular necrosis of the hip is a condition characterized by the death of the femoral head due to disruption of its vascular supply, mainly by Medial Femoral Circumflex Artery. It leads to insidious onset of hip pain, usually with movement, and can be the result of a variety of factors. Some of the most common causes can be remembered by the mnemonic “ASEPTIC”:

• Alcohol/AIDS
• Steroids, sickle cell disease, SLE
• Erlenmeyer flask (Gaucher disease)
• Pancreatitis
• Trauma
• Idiopathic (Legg-Calve-Perthes disease), infection, iatrogenic
• Caisson disease

The neurologic injury usually is associated with traumatic dislocation and fracture-dislocation of the hip. The sciatic nerve, usually the peroneal branch, is most often injured, and this complication can be seen after all types of posterior fracture-dislocations and simple posterior dislocations. The sciatic nerve can be acutely lacerated, stretched, or compressed, or later encased in heterotopic ossification. Neurologic examination at the time of injury often is difficult but is extremely important. Rehabilitation of patients with sciatic nerve injury must begin as early as possible and should focus on the prevention of an equinus foot deformity.

Intramuscular injection is one of the complications and the sciatic nerve is the most frequently affected nerve, especially in children, the elderly and underweight patients. The neurological presentation may range from minor transient pain to severe sensory disturbance and motor loss with poor recovery. Management of nerve injection injury includes drug treatment of pain, physiotherapy, use of assistive devices and surgical exploration. Early recognition of nerve injection injury and appropriate management is crucial in order to reduce the neurological deficit and maximize recovery. If the injection has to be administered into the gluteal muscle, the ventrogluteal region (gluteal triangle) has a more favourable safety profile than the dorsogluteal region (the upper outer quadrant of the buttock).