You are examining a 65 year old lady who has been brought in by ambulance with suspected hip dislocation. Which of the following ligaments is most significant in resisting hyperextension of the hip joint:
The hip joint is a multiaxial synovial ball and socket joint occurring between the head of the femur and the acetabulum of the pelvis.
Joint | Hip |
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Type | Synovial ball and socket joint |
Articulations | Head of femur with acetabulum of pelvis |
Stabilising factors | Acetabular labrum, thickened fibrous capsule, extracapsular ligaments (iliofemoral, ischiofemoral, pubofemoral), medial rotator muscles (effectively ‘pull’ head of femur into acetabulum) |
Movements | Flexion/Extension, Abduction/Adduction, Medial/Lateral rotation, Circumduction |
Blood supply | Branches of obturator artery, medial and lateral circumflex branches of profunda femoris artery and superior and inferior gluteal arteries |
Innervation | Femoral nerve, obturator nerve, superior gluteal nerve and nerve to the quadratus femoris |
The acetabulum is formed by the fusion of the three bones, the ilium, the ischium and the pubis.
The rim of the acetabulum is raised slightly by the fibrocartilaginous acetabular labrum which increases its depth, improving stability of the joint. The acetabular labrum continues inferiorly as the transverse acetabular ligament which bridges the acetabular notch and converts the notch into a foramen for the passage of nutrient vessels and nerves.
The intracapsular ligament of the head of femur (ligamentum teres) runs from the fovea on the head of the femur at one end to the acetabular fossa and the transverse acetabular ligament on the other. It carries a small acetabular branch of the obturator artery.
There are three main stabilising extracapsular ligaments; the iliofemoral (the largest and strongest ligament), the pubofemoral and the ischiofemoral ligament.
The hip joint receives its blood supply primarily from branches of the obturator artery, the medial and lateral circumflex arteries (branches of the profunda femoris artery) and the superior and inferior gluteal arteries. The articular branches of these vessels form a network around the joint.
The hip joint is innervated by articular branches from the femoral nerve (anteriorly), obturator nerve (inferiorly), superior gluteal nerve (superiorly), and the nerve to the quadratus femoris (posteriorly).
The hip joint allows the movements of flexion and extension, abduction and adduction, medial and lateral rotation and circumduction.
Movement | Muscles Involved |
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Flexion | Sartorius, Iliacus, Psoas major, Pectineus, Rectus femoris |
Extension | Hamstrings, Gluteus maximus |
Abduction | Gluteus maximus, medius and minimus, Obturator internus, Gemelli, Piriformis, Sartorius |
Adduction | Adductor longus, magnus and brevis, Gracilis, Pectineus |
Medial rotation | Gluteus medius and minimus, Adductor longus, magnus and brevis, Semitendinosus and Semimembranosus |
Lateral rotation | Obturator externus, Sartorius, Iliacus, Psoas major, Biceps femoris, Piriformis, Gluteus maximus, Obturator internus, Gemelli, Quadratus femoris |
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Biochemistry | Normal Value |
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Sodium | 135 – 145 mmol/l |
Potassium | 3.0 – 4.5 mmol/l |
Urea | 2.5 – 7.5 mmol/l |
Glucose | 3.5 – 5.0 mmol/l |
Creatinine | 35 – 135 μmol/l |
Alanine Aminotransferase (ALT) | 5 – 35 U/l |
Gamma-glutamyl Transferase (GGT) | < 65 U/l |
Alkaline Phosphatase (ALP) | 30 – 135 U/l |
Aspartate Aminotransferase (AST) | < 40 U/l |
Total Protein | 60 – 80 g/l |
Albumin | 35 – 50 g/l |
Globulin | 2.4 – 3.5 g/dl |
Amylase | < 70 U/l |
Total Bilirubin | 3 – 17 μmol/l |
Calcium | 2.1 – 2.5 mmol/l |
Chloride | 95 – 105 mmol/l |
Phosphate | 0.8 – 1.4 mmol/l |
Haematology | Normal Value |
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Haemoglobin | 11.5 – 16.6 g/dl |
White Blood Cells | 4.0 – 11.0 x 109/l |
Platelets | 150 – 450 x 109/l |
MCV | 80 – 96 fl |
MCHC | 32 – 36 g/dl |
Neutrophils | 2.0 – 7.5 x 109/l |
Lymphocytes | 1.5 – 4.0 x 109/l |
Monocytes | 0.3 – 1.0 x 109/l |
Eosinophils | 0.1 – 0.5 x 109/l |
Basophils | < 0.2 x 109/l |
Reticulocytes | < 2% |
Haematocrit | 0.35 – 0.49 |
Red Cell Distribution Width | 11 – 15% |
Blood Gases | Normal Value |
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pH | 7.35 – 7.45 |
pO2 | 11 – 14 kPa |
pCO2 | 4.5 – 6.0 kPa |
Base Excess | -2 – +2 mmol/l |
Bicarbonate | 24 – 30 mmol/l |
Lactate | < 2 mmol/l |