I. Anatomical features The posterior 1/3 of the heel bone protrudes posteriorly and is called the heel tuberosity, which is saddle-shaped and covered by fat. The posterosuperior margin protrudes posteriorly and superiorly as the posterosuperior heel tuberosity, also known as the bursal eminence. The heel bone has an unsmooth protruding form posteriorly, below the bursal process, and protrudes posteriorly medially as the posterior lateral heel tuberosity. On the metatarsal side of the heel tuberosity, there is a larger medial tuberosity and a smaller lateral tuberosity. The Achilles tendon stops at the posterior heel tuberosity below the bursal process, and the width of the stop is 1.2 to 2.5 cm. There is a bursa between the Achilles tendon and the posterior superior heel tuberosity, called the Achilles tendon capsule. The anterior wall of the Achilles tendon capsule is the fibrocartilage tissue attached to the heel bone, and the posterior wall is the peritendinous tissue of the Achilles tendon. There is a fat pad in front of the Achilles tendon bursa and a bursa between the Achilles tendon and the heel skin, called the subcutaneous bursa. The bursa can play a lubricating role between the Achilles tendon and the heel tuberosity as well as with the skin when normal. When the foot is dorsiflexed, the Achilles tendon and Achilles tuberosity will squeeze the bursa; while in plantarflexion, the pressure on the bursa will be reduced. The etiology and pathology of achilles tendinopathy is not well understood. Such lesions can occur not only in athletes, but also in middle-aged and elderly people who do not exercise well. Achilles tendinitis in athletes may be caused by inadequate preparation for exercise, sudden changes in exercise volume, and frequent activity on uneven or sloped surfaces. The Achilles tendon is subjected to excessive abnormal and repetitive stresses and then micro-tears occur. In contrast, non-athlete stopping Achilles tendonitis, which is generally seen in middle-aged and older women who are overweight, may occur more as a result of degeneration rather than overactivity. In addition, abnormalities in the force lines of the foot are also causes of Achilles tendon injury and degeneration. For example, excessive rotation of the foot is an imbalance in the stress on the Achilles tendon, and the moment of the Achilles tendon increases, adding to the load on the Achilles tendon. The high arch of the foot weakens the foot’s role in absorbing ground stress during walking and increases the stress on the Achilles tendon. Posterior heel pain can also be caused by a number of systemic diseases, such as ankylosing spondylitis and gout. In patients with stopping point Achilles tendinitis, fibro-mucinous degeneration occurs at the stopping point of the Achilles tendon and eventually fibrosis and calcification, thickening of the Achilles tendon with nodule formation. More commonly, achilles tendinitis is combined with changes in other surrounding structures. For example, the posterior superior Achilles nodule may become hypertrophic and inflame the Achilles tendon capsule causing pain. Pain can also be caused by inflammation of the subcutaneous capsule caused by friction between the skin of the protruding area and the shoe upper after wearing narrow or stiff shoes. Since Patrick Haglund first described this lesion in 1928, the posterior superior heel node can be hyperplastic and hypertrophic and is also known as Haglund’s deformity. Clinical manifestations Stopping point Achilles tendonitis in athletes often manifests as pain in the heel during exercise. It usually does not affect daily activities. Non-athlete’s achilles tendonitis may gradually appear as pain in the posterior part of the heel. It starts as intermittent pain and may become constant pain. The Achilles tendon stop is normal or enlarged in appearance, with localized painful pressure. It makes it difficult or painful for the patient to lift the heel with one foot. In a small number of patients, rupture of the Achilles tendon may occur with activity and a positive Thompson test. Achilles tendon capsulitis usually develops in middle-aged and elderly people who do not exercise much. The typical course of the disease is sudden onset of pain and localized swelling in the posterior heel. Local skin temperature may be elevated, and there may be pressure pain on both the medial and lateral aspects of the Achilles tendon, which may be aggravated by passive dorsiflexion of the ankle. Haglund deformity usually occurs in young people. It presents as a posterior lateral protrusion of the heel tuberosity. If not combined with bursitis there may be no clinical symptoms. The skin of the bone protrusion and the abrasion of the shoe upper cause localized skin redness and pain. However, in many patients, stopping point Achilles tendinitis, Achilles bursitis and Haglund deformity are present together. Laboratory tests are performed to check blood uric acid, as well as HLA-B27 and other tests to determine the presence of gouty arthritis and ankylosing spondylitis. Radiographic manifestations: the loss of the anterior Achilles tendon capsule shadow was seen on the lateral X-ray, the widening of the Achilles tendon by more than 9 mm in the 2 cm above the bursal eminence, and calcification and bone formation were seen at the Achilles tendon attachment. There are three types of bursal prominence patterns, and an enlarged bursal prominence may cause irritation and inflammation of the Achilles tendon. Therefore, there are some X-ray measurements for evaluation. Posterior heel angle: On the heel radiograph, posterior to the heel tuberosity, the line connecting the posterior border of the bursal process to the posterior border of the posterior tuberosity and the line connecting the inferior border of the medial tuberosity to the inferior border of the anterior inferior tuberosity of the heel, the angle of intersection of the two lines becomes the posterior heel angle. This measurement was first proposed by Fowler and Philip in 1945 and is also known as the Fowler CPhilip angle. They concluded that this angle ranges from 44° to 69° in normal subjects, and that an angle greater than 75° indicates an abnormally large bursal process, which may cause heel pain. Pavlov concluded that the size of the posterior heel angle is not related to heel pain but to the degree of upward protrusion of the bursal process, and proposed the use of parallel spacing lines to measure the degree of protrusion of the bursal process. Parallel spacing line: On the heel x-ray, the line connecting the inferior border of the medial heel tuberosity and the inferior border of the anterior inferior heel tuberosity is made parallel to the above line through the posterior border of the articular surface of the heel talus. Under normal conditions, the bursal process does not go upward beyond the 2nd line. Chauveaux and Liet thought that the parallel inclined lines did not reflect the relationship between the bursal process and the Achilles tendon, and also proposed to measure the angle of intersection between the vertical line of the horizontal line and the line connecting the bursal process and the posterior lateral tuberosity (C-L angle) after weight-bearing of the foot to determine the relationship between the bursal process and the Achilles tendon. However, some other physicians have found no direct correlation between the magnitude of these angles and the patient’s symptoms. MRI is generally not used as a routine test. If non-surgical treatment fails and surgical treatment is needed, MRI can clearly show the protrusion of Achilles tendon, bursa and heel nodes for the convenience of surgical plan design. Treatment 1. Non-surgical treatment 95% of patients can achieve better results with non-surgical treatment. (1) For athletes with stopping Achilles tendonitis, the amount of exercise should be appropriately reduced and running and jumping on ramps or hard surfaces should be avoided. Severe symptoms may require rest or braking for 4 to 6 weeks. (2) Cold compresses can be used after exercise. (3) Non-steroidal anti-inflammatory and pain-relieving drugs (NSAIDs). Hormone injections may be used for Achilles tendon capsule inflammation, but do not inject into the Achilles tendon. For gout, colchicine and allopurinol are needed, and for rheumatoid arthritis, appropriate medical management is needed. (4) Wear soft shoes to reduce the compression of the Achilles tendon stop, and use Achilles tendon socks with silicone pads for protection. Heel elevation reduces the stress on the Achilles tendon. Orthopedic shoes or foot pads can correct the poor force line of the foot. (5) Physical therapy, gentle pulling exercises on the Achilles tendon. (6) For non-athlete stopping point Achilles tendonitis, the above non-surgical treatment methods can also be tried first. But generally bad activity of middle-aged and elderly patients, the effect of non-surgical treatment is poor, may need surgery. 2.Surgical treatment Surgical treatment can remove the degenerative and inflammatory tissues of Achilles tendon, bursa and hyperplasia of the posterior superior calcaneal nodes. The surgical approach can be medial, lateral, bilateral or trans-Angel tendon approach. A lateral incision is usually used to avoid injury to the medial calf sensory nerve. The inflammatory bursa tissue is first removed, and then a bone knife or bone saw is used to start approximately 1.5 cm anterior to the posterior border of the Achilles bone and proceed obliquely down to the Achilles tendon stop, taking care to completely remove the remaining bone crest in front of the Achilles tendon to avoid postoperative irritation of the Achilles tendon, which can cause pain. An excision of 2 cm above the Achilles tendon stop is generally safe. Occasionally, excision of too much of the posterosuperior tuberosity may involve the Achilles tendon stop; an attachment incision of the lateral border of the Achilles tendon can also be seen when needed to allow for excision of the Achilles tuberosity. The tendon tissue above the Achilles tendon stop is explored for degeneration and calcification, and the diseased tendon tissue is excised and repaired with 3-0 non-absorbable sutures. The cut Achilles tendon stop can be perforated on the heel bone and sutured with 2 non-absorbable thread or fixed with soft tissue fixation anchors. Achilles tendon debridement for stopping point Achilles tendinitis can also be performed via a median or oblique approach to the Achilles tendon (Dickinson approach). If the Achilles tendon stops are long and extensive, the Achilles tendon attachment is lost after removal of the diseased tissue, the Achilles tendon stops need to be reconstructed. If the stop cannot be reconstructed, tendon transposition is required to reconstruct the Achilles tendon. Post-operative complications include: 1. Wound non-healing infection. General wound dressing can be cured. 2.Peroneal nerve injury. The lateral heel is numb, but rarely causes long-term poor functional results. 3.Symptoms recur and remain painful after surgery. It is necessary to check whether the bone removal is sufficient and whether the clearing of diseased tissue within the Achilles tendon is complete. Those with severe symptoms may need to operate again to completely remove the diseased tissue and strengthen the Achilles tendon with flexor hallucis longus tendon or flexor digitorum longus tendon transposition. 4. Rupture of the Achilles tendon attachment point. It often occurs within 6 to 8 weeks after surgery and is caused by trauma again. Re-surgical suturing is required.