Skoryk I. Restoration of knee joint extensor mechanism under conditions of proximal tibia modular endoprosthesis (experimental-clinical study).

Today, the most effective method of treating patients with proximal tibia tumors is removal of the tumor "en block" and replacing the post-resection defect with a modular tumor implant. However, the number of complications remain significant (from 40% to 70% in the period from 5 to 15 years after surgery), among them is the failure of the extensor mechanism of the knee joint accounts for about 5.8-12%. The objective of the study is: To increase the functional results of surgical treatment of patients with proximal tibia malignant tumors by improving the method of replacement of post-resection defects with modular endoprostheses and reconstruction of the knee joint extensor mechanism. The object of the study is surgical treatment of patients with proximal tibia tumors using modular endoprostheses. Methods: clinical; radiological (radiography, spiral computed tomography and magnetic resonance imagine); retrospective analysis; biomechanical; experimental modeling and histological; statistical. The indications and contraindications for proximal tibia modular tumor endoprosthesis are specified, an improved method of surgery is proposed, which allows to get better functional results and minimize a surgical complications rate in the complex therapy system of patients with proximal tibia malignant tumors. A method of fixation of knee extensor mechanism to implant module is proposed, which allows to obtain early knee joint function and to restore full limb weight bearing. Options for restoration of the extensor mechanism of knee joint and soft tissue defect depending on volume of tibia bone tumor mass removal have been optimized and implemented into clinical practice. Scientific novelty of the obtained results. For the first time, we researched the loading on the extensor apparatus of pig knee at physical biomechanical model and found that the attachment of patellar ligament to the tibia with microporous polyethylene terephthalate is 1.4 times (p < 0.01) stronger than fixation with nylon tape. For the first time, microporous polyethylene terephthalate was identified as optimal coating material for a modular endoprosthesis for knee extensor apparatus fixation, based on study of morphological features of patellar ligament regeneration using in-vivo experiment. The formation of tendon-like tissue in the area of patellar ligament injury and slightest manifestation of destructive changes in it at all observation in the case of microporous polyethylene terephthalate fixation was compared to titanium with or without corundum ceramics coating (p < 0.001). Based on the retrospective analysis of clinical material and literature data, it was determined that failure of the extensor apparatus of knee joint ranks second the place in frequency (5.8 to 12 %) among the complications of proximal tibia modular tumor endoprosthesis after periprosthetic infection (11 to 36 %). The usage of designed method of reconstruction of the knee extensor mechanism made it possible to avoid its failure in early and late postoperative period after primary proximal tibia modular endoprosthesis under full weight bearing and without usage of external fixators. The results of the manuscript were introduced into the scientific and clinical work of the Ukrainian National Academy of Medical Sciences “Sytenko Institute of Spine and Joint Pathology”, clinical practice of the Kharkiv Municipal non-commercial enterprise of the Kharkiv regional coundil “Regional Clinical Hospital”, of the Kharkiv Municipal non-commercial enterprise of the Kharkiv regional coundil “Regional Clinical Traumatologycal Hospital”, Municipal non-commercial enterprise " City Clinical Hospital of Ambulance and Emergency Medicine. prof. OI Meshchaninov ”of the Kharkiv City Council, National Cancer Institute of the Ministry of Health of Ukraine. Field of use - medicine (traumatology and orthopedics).