Autologous adipose tissue injection versus platelet-rich plasma (PRP) injection in the treatment of knee osteoarthritis: a randomized, controlled study – study protocol

All activities related with the study will be performed at the Department of Spine Disorders and Pediatric Orthopedic Surgery, Poznan University of Medical Sciences and Rehasport Clinic in Poznan, Poland. These include patient identification, explanation of all procedures, treatment and functional assessment. The same inclusion criteria have been established for an Experimental Group (subjects treated with autologous fat tissue) and a Control Group (subjects treated with PRP). Those criteria consist of: symptomatic knee OA, age between 45 and 65 y.o., Kellgren- Lawrence grades I – III OA, no or minimal positive effects of previous conservative treatment (rehabilitation, hyaluronic acid injections, steroid injections), VAS pain level minimum 4 in one knee, VAS pain < 2 in the contralateral knee. Those patients who meet inclusion criteria will be allocated to Fat Tissue Group or PRP Group randomly (Fig. 1). The exclusion criteria were as follows: use of local corticosteroids up to 3 months or hyaluronic acid injections up to 6 months prior to the study, past or present joint infection, previous knee arthroscopy surgery up to 1 year prior to examination, peripheral inflammatory diseases (rheumatoid arthritis, spondyloarthropathies, etc.), total arthroplasty and osteotomy, ankylosis of the joint, dermatitis or dermatological disease at the intended injection site, coexistence of degenerative changes in other limb joints (hip, foot), cancer, oral corticosteroid therapy, use of medicines that affect blood clotting, pregnancy or breast-feeding. Before randomization, patients will sign a suitable consent form. All participants will be obliged not to use any anti-inflammatory drugs for the entire duration of the study. Moreover, every volunteer will receive a brochure approved by Research and Development Department which contains all of the information regarding protocol (procedures, outcomes assessments, schedule of visits, researchers team, possible complications). Draw is made at the Doctor’s room after subject’s qualification and the participant choose the number of the group 1 or 2, Fat Tissue Treatment or PRP treatment, respectively. At the stage of treatment there is no possibility for patients to be blinded because the procedure requires adipose tissue harvesting. However, during all other stages, the procedure will be blinded, in a database each participant will have a special code to minimize the risk of identification as well as reporter biases.

Lipoaspiration will take place in the operating room under general anesthesia for patient’s and doctor’s comfort. The most frequent donor site is abdomen [14, 15]. The patient will be placed in a supine position. At first, two small incisions at the level of umbilicus will be made by the trained orthopaedic surgeon (TP or PB). Then Klein solution (saline with lidocaine and epinephrine) will be infused to reduce bleeding. Ten minutes is required for infiltration. Next step is a liposuction performed with a thin cannula inserted through incisions. Finally, skin sutures and the pressure dressing will be applied. To minimize risk of bleeding and hematoma, an elastic belt will be recommended, as well as partial weight bearing within first 2 weeks. Harvested adipose tissue will be prepared in a Lipogems kit [14]. The final product will be transferred into 10-ml syringes. About 10 ml of the product will be injected into the affected knee joint. After several hours of observation, the patient will leave the clinic with 2 elbow crutches. For the first 2 weeks, partial weight-bearing will be allowed as tolerated. After 2 weeks, full-weight loading will be allowed. Patients will be instructed to perform physical exercises, including cycling, swimming and full-body exercises. No physical therapy will be recommended.

PRP preparation takes place in an outpatient clinic. The whole process, from blood collection to PRP injection, takes approximately 10 min. It takes places in the treatment room at room temperature and day light exposure. No commercial kit are used. 10-ml sterile collecting tubes containing citrate will be placed in a centrifuge (Centrifuge MPW- 223e) with a tilting rotor. Rotation will last 7 min at 2320 * g. After centrifugation, PRP will be collected up to 3 ml for separate 10-ml syringe. 3 ml of PRP will be injected into the knee joint. Procedure will be repeated three times in 7 day interval.

Joint injection will be performed by TP or PB in the same manner for both groups: patient placed in supine position, affected knee extended, a 21-Gauge needle inserted into the suprapatellar pouch, in case of joint effusion – aspiration of synovial fluid and finally administration of autologous fat tissue or PRP.

For the first 2 weeks after injections patients will be asked to limit their activity. 2 weeks after the third injection, normal activity will be allowed. Patients will be instructed to perform physical exercises, including cycling, swimming and full-body exercises. No physical therapy will be recommended.

Patients will be assessed five times: before treatment and 1, 3, 6 and 12 months after the treatment (Table 1). The PROMs consist of the four questionnaires: The Knee injury and Osteoarthritis Outcome Score (KOOS) [16‐18], International Knee Documentation Commitee 2000 (IKDC 2000) [19, 20], the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) [21, 22], the Health Questionnaire EQ- 5D- 5 L [23, 24].

Moreover, three functional tests will be performed to assess patient’s functional status: The Timed Up and Go Test (TUG) [25], The 5 Times Sit to Stand Test (5xSTS) [26], The 10 m Walk Test (10mWT) [27]. To assess strength parameters of the knee flexors and extensors the Maximal Voluntary Isometric Contraction (MVIC) will be measured. Each test will be supervised by the same one physiotherapist to avoid any interexaminer bias and discrepancies during testing.

The Knee injury and Osteoarthritis Outcome Score is currently culturally adapted in 39 languages, including polish [18, 28]. The polish version has already been validated [17]. It is used for knee OA assessment and for the evaluation of the effect of many orthopedic surgeries as well [16].

International Knee Documentation Committee 2000 has been developed to assess function, symptoms and sports activity in patients with variety of knee joint conditions such as: OA, meniscal and/or ligamentous injuries, patellofemoral pain [19]. This questionnaire also has been adapted to the polish language [20].

The Western Ontario and McMaster Universities Osteoarthritis Index has been developed for knee and/or hip joints OA symptoms assessment. This questionnaire has been extensively tested for reliability and validity in measuring changes in patients’ symptoms in affected joints [21, 22]. There is no polish cultural adaptation of WOMAC that is why WOMAC index will be calculated from KOOS [29].

The Health questionnaire EQ- 5D- 5 L measures general health status including function, physical symptoms and emotional dimensions which are relevant even for healthy individuals. EQ- 5D- 5 L is 5- level, more sensitive version of the original 3- level version (EQ- 5D- 3 L) [24]. Polish population norms for the EQ- 5D- 5 L has already been established [23].

MVIC measurement is performed with Forcemeter FB 500 (AXIS, Gdansk, Poland). The patient sits on a bench with the belt around waist and legs placed freely beyond the table. The measuring belt is placed parallel to the floor just above the ankle joint with knee flexed to 90 degrees. The measuring belt length is strictly specified: for MVIC of extensors 160 cm, for MVIC of flexors 60 cm.

The procedure starts with the measuring belt pretension, then the patient is asked to extend/flex the knee as hard as he/she can and hold it for 6 s. The force is measured in Newtons [N]. The results is divided by the patient’s weight [kg] for data analysis.

Nowadays, PRP is commonly used in medicine to enhance expression of growth factors and cell rebuilding process not only in orthopedics but dermatology and dentistry as well [30, 31]. In OA treatment PRP is thought to have an influence on the whole joint environment by increasing chondrocyte proliferation [32], reduction of the inflammatory process [33, 34] and enhancing the secretion of hyaluronic acid (HA) as well [35]. It is well established that PRP is more effective in knee OA treatment than placebo (saline intra-articular injections) [12, 36‐39]. More discrepancies among researchers exist when it comes to comparing the effectiveness of PRP and HA treatment. Some authors have found no differences between the groups treated with PRP and HA [34, 36], others [40‐42] prove PRP injections alone or in combination with HA to be more effective than HA injections alone.

The autologous fat tissue, which contains numbers of pericytes [37, 38], serves as a kind of drugstore after the injection into the affected joint. It is thought that they secrete bioactive molecules and stimulate other type of cells by cell- cell contact [37]. The effects of autologous fat tissue activity are apoptosis inhibition, enhancement of angiogenesis and stabilization of the new vessels, stimulation of the progenitors to appropriate differentiation [37, 39]. Some authors combine intra-articular injections of autologous fat tissue with arthroscopic debridement [15, 43, 44] or microfractures [45‐47], but autologous fat tissue alone may also improve degenerated joint condition [42, 48‐51].