Calcaneous tuberosity joint angle

The calcaneal tuberosity joint angle, also known as the Bohler angle, is the angle formed by the upper edge of the calcaneal tuberosity and the talocalcaneal articular surface, which is normally 30-45 degrees. It is one of the important signs of the relationship with distance. What important physiological significance does the calcaneal tuberosity joint angle have in the human body? What role does it play in the human body? Let us take a closer look at the structure and function of the calcaneal tuberosity joint angle.

Introduction

The angle formed by the line connecting the calcaneal tuberosity and the posterior articular process of the calcaneus and the line connecting the anterior and posterior articular processes of the calcaneus. (Renwei seventh edition of surgery book, page 798)

Anatomical features of the calcaneus

1. The calcaneus is the largest tarsal bone in the foot. It is an irregular rectangular structure composed of a thin layer of cortical bone surrounding abundant cancellous bone.

2. The calcaneus is irregular in shape, with six faces and four articular surfaces. There are three articular surfaces on the top, namely the anterior talar, mid talar, and posterior talar articular surfaces. The three articulate with the anterior, middle and posterior articular surfaces of the talus respectively to form the subtalar joint. There is a wide groove between the middle and posterior subtalar joints that opens outward, called the tarsal sinus.

3. There is a protrusion in front of the calcaneus called the anterior calcaneal tubercle. The bifurcated ligament originates from this tubercle and ends at the cuboid bone and navicular bone. The anterior articular surface of the calcaneus is saddle-shaped and articulates with the cuboid bone.

4. The subcutaneous tissue on the outer side of the calcaneus is thin, and the bone surface is wide and flat. There is a tubercle in the front which is the peroneal trochlea, and there is an oblique groove in the lower back and upper front for the long and short tendons of the peroneus to pass through respectively.

5. The subcutaneous soft tissue on the medial side of the calcaneus is thick, and the bone surface is arc-shaped and concave. There is a flat protrusion in the middle 1/3, which is the load-bearing protrusion. Its cortical bone is thick and hard. The talar process is attached with the triangular ligament, plantar calcaneal ligament (spring ligament), etc. A bundle of blood vessels and nerves passes through the inner side of the calcaneus.

6. The posterior part of the calcaneus is wide and moves downward to the calcaneal tuberosity, where the Achilles tendon is attached. There are two protrusions on the plantar side, the medial process and the lateral process, which are the starting points of the plantar fascia and the small muscles of the plantar foot.

7. The calcaneal trabeculae are arranged into two fixed groups according to the direction of pressure and tension they bear, namely compression trabeculae and tension trabeculae. An osteoporotic area is formed between the two groups of trabeculae, which appears as a triangle on the lateral X-ray and is called the central triangle of the calcaneus.

8. After a calcaneal fracture, changes in two angles can often be seen on the lateral X-ray of the calcaneus. The calcaneal tuberosity joint angle (Bohler angle) is normally 25°~40°, which is the angle formed by the lines connecting the highest point of the posterior articular surface of the calcaneus to the calcaneal tuberosity and the highest point of the anterior tuberosity. The calcaneal intersection angle (Gissane angle) is the angle between the line from the bottom of the lateral groove of the calcaneus to the highest point of the anterior tuberosity and the posterior articular surface line, which is normally 120°~145°.