The DCWCO changes the anatomical length of the calcaneus, and it elevates the distal insertional point of the calcaneal tendon to induce a mechanical advantage, consequently alleviating pain and permitting a fast recovery [1, 13, 24].
Our data demonstrated that a successful change of the CL angle, which is represented by the difference between the angle of verticalization (α) and the morphological angle (β) of the calcaneus (CL angle = α − β), could be achieved by different direction and a different size of the osteotomy direction in minimally invasive-dorsal closing wedge calcaneal osteotomy (MIS-DCWCO) (Table 1). We proved that the change of the alpha angle depends on the osteotomy direction and the alpha angle mostly affects the horizontal type of the osteotomy (dotted) (Fig. 2). On the other hand, the direction of the osteotomy does not affect the beta angle. We further showed that the size of the osteotomy affects the beta angle but does not affect the alpha angle. We could use this fact in preoperative planning, where we would consider the postoperative change depending on the morphology of the calcaneus.
The osteotomy changes the length of the plantar aponeurosis. The study measured the changing of the distance between the medial sesamoid bone of the first metatarsophalangeal joint and the lowest point of the calcaneus (Table 2). We proved that the vertical osteotomy (dashed one) has the greatest reduction in the plantar aponeurosis length. On the other hand, in the horizontal type of the osteotomy (dotted one) there has been a relative prolongation of the plantar aponeurosis. It is important to always assess the functional complex of the triceps surae muscle and plantar aponeurosis. If there is a large change in the length of the plantar aponeurosis, pain can occur in the area of the sole, known as plantar fasciitis.
The most significant elevation of the distal insertional point of the calcaneal tendon occurred in the horizontal (dotted one) type of the osteotomy. If we take into account the change in complex of the plantar aponeurosis and triceps surae muscle, the horizontal type of the osteotomy seems to be the most advantageous for DCWCO.
Insertional tendinopathy is caused by chemical attrition and bony mechanical abrasion [10]. The first-line treatment of the insertional tendinopathy is a conservative management. Operative treatment is indicated after six months of unsuccessful conservative treatment.
There are several operative treatments for refractory insertional tendinopathy. Surgical treatment can be divided into open and mini-invasive procedures. Open resection of the Haglund's deformity is still a standard procedure [12]. However, open procedures are associated with a high rate of complications. [10, 16]. The second group of surgical treatment consists in a minimally invasive procedure. The first option is the endoscopic bony and soft-tissue decompression with arthroscopic shaver [15, 23]. The second mini-invasive surgical treatment option is the minimally invasive-dorsal closing wedge calcaneal osteotomy (MIS-DCWCO), which we focused on in our study. We proved that certain types of the osteotomy affect the change of alfa and beta angles which should reduce pain.