Table 2.

Comparative studies of PRP in the treatment of elbow pathologies. VAS (Visual Analogue Scale), PRTEE (Patient-Rated Tennis Elbow Evaluation questionnaire), DASH (Disabilities of the Arm, Shoulder and Hand score), ABI (Autologous Blood Injection)

Author	Year	PRP preparation	Study design	No. of cases (n)	Outcome scores	Comments
Palacio et al. [27]	2016	60 ml of blood was divided between six 10-ml tubes that contained sodium citrate. These tubes were then subjected to two cycles of centrifugation, under forces of 400g and 800g, for 10 min. Two thirds of the original volume (platelet-poor plasma) was discarded and only one third of the original blood sample consisted of PRP	PRP vs steroid	PRP (20), steroid (20)	DASH, PRTEE	No significant difference in scores among both groups
Gautam et al. [23]	2015	20 ml of blood was collected in an acid citrate dextrose vacutainer and centrifuged at 1500 rpm for 15 min to separate the blood into layers of red blood cells, buffy-coat of leucocytes, and plasma.	PRP vs steroid	PRP (15), steroid (15)	VAS, DASH, modified Mayo score, hand grip strength, ultrasound	All scores improved significantly from pre-injection to the 6-month follow-up in the PRP and CS groups. However, in the CS group, the scores generally peaked at 3 months and then deteriorated at 6 months indicating recurrence. Higher incidence of reduced tendon thickness and condylar erosions in the CS group
Khaliq [26]	2015	Not described	PRP vs steroid	PRP (51), steroid (51)	VAS	Significant improvement in VAS scores in the PRP group
Lebiedziński et al. [19]	2015	PRP prepared using (Double Syringe System, Arthrex)	PRP vs steroid	PRP (53), steroid (46)	DASH	Mean DASH score at 1 year was significantly better in the PRP group though at 6 weeks and 6 months it was significantly better in the steroid group
Yadav [24]	2015	Patients received a single injection of PRP (1 ml), with absolute platelet count of 1 million platelets/mm3 as confirmed by manual counting. PRP was injected into the common extensor origin at the lateral epicondyle of the humerus under aseptic conditions. PRP was prepared under aseptic conditions as per the procedure standardized in the departmental laboratory. A 9001:2000 ISO-certified R-23 centrifuge was used for the purpose of platelet concentration.	PRP vs steroid	PRP (30), steroid (30)	VAS, DASH, grip strength	At 3 months, significant improvement in pain and function scores in the PRP group (Steroid group had better initial pain relief which declined subsequently)
Behera et al. [25]	2015	100 ml blood was collected into an anticoagulant blood bag and centrifuged at 1500 rpm for 15 min. The supernatant fluid was transferred into another blood bag. Leukocytes were filtered out using a filter (Imuguard III-PL, Terumo Penpol, Thiruvananthapuram, India) to obtain leukocyte poor PRP, with the platelet count between 6 and 8 × 105/μL, and the leukocyte count a 3-log reduction. Under ultrasonographic guidance, 3 ml of type-4B PRP and 0.5 ml of calcium chloride was injected.	PRP vs bupivacaine	Leucocyte poor PRP (15), bupivacaine (10)	VAS MMCPIE score, Nirschl score	Significant improvement in all scores in the PRP group at 3 months (Steroid group had better initial results which declined subsequently)
Raeissadat et al. [31]	2014	The PRP processing was done using the Rooyagen kit (made by AryaMabnaTashkhis Corporation, RN: 312569). For preparing 2 ml of PRP with concentration of 4–6 times the average normal values, 20 ml of blood was first collected from the patient’ s upper limb cubital vein using an 18-G needle. Then 2 ml of ACD-A was added to the sample as an anticoagulant. One milliliter of the blood sample was sent for complete blood count. The rest of the sample passed two stages of centrifugation (first with 1600 rpm for 15 minutes for separation of erythrocytes and next with 2800 rpm for 7 min in order to concentrate platelets). The final product was 2 ml of PRP containing leukocytes (leukocyte-rich PRP). The PRP quantification and qualification procedure was performed using laboratory analyzer Sysmex KX 21 and swirling and if approved, the injection was performed	PRP vs autologous blood	Leucocyte-rich PRP (33) ABI (31)	VAS, MAYO score, pressure pain threshold	Although scores of both groups improved over 12 months, no significant difference between PRP vs ABI
Mishra et al. [29]	2014	30 mL of whole blood was drawn from a peripheral vein of each patient. In the PRP group, the blood was mixed with an anticoagulant (ACD-A) and placed into a sterile separator canister (GPS, Biomet Biologics, Warsaw, Indiana). The canister was then placed in a desktop-sized centrifuge and processed for 15 min at 3200 rpm producing type 1A PRP (leukocyte-enriched PRP with platelets 5 times the baseline used in an inactivated manner). The PRP was then removed and buffered to physiological pH using 8.4% sodium bicarbonate to neutralize the acidic ACD-A in the PRP.	Leucocyte-enriched PRP vs active control	PRP (116) Controls (114)	VAS with resisted wrist extension PRTEE scores	Significant pain improvement at 24 weeks compared with controls. No difference in PRTEE scores
Krogh et al. [20]	2013	For the PRP, 27 mL of whole blood was collected into a 30-mL syringe containing 3 mL sodium citrate (anticoagulant) and then placed in a disposable cylinder in a centrifuge for 15 min at a speed of 3.2 (31,000 rpm). Platelets were collected using the Recover GPS II system (Biomet Biologics Inc., Warsaw, Indiana) producing 3 to 3.5 mL of PRP, with a platelet concentration increased on average by 8-fold compared with whole blood. To achieve a physiological pH, the PRP was buffered with 8.4% sodium bicarbonate.	PRP vs steroids vs saline	PRP (20), steroid (20), saline (20)		No significant improvement in pain at 3 months compared to saline or steroids
Gosens et al. [21]	2011	The PRP preparation was done using the Recoversystem (Biomet Biologics, Warsaw, Indiana).	PRP vs steroids	PRP (51), steroid (49)	VAS DASH	Significant improvement in VAS and DASH scores at 2 years of PRP group (DASH scores of steroid groups returned to baseline levels while those of the PRP group improved)
Thanasas [33]	2011	For the PRP preparation, the Biomet GPS III was used. This system uses, under aseptic technique, 27 to 55 mL of autologous peripheral blood with 3to 5 mL of anticoagulant, centrifuges it at 3200 rpm for15 minutes, and finally extracts 3 to 6 mL of PRP. No activator was used.	PRP vs autologous whole blood injection	PRP (14), autologous whole blood (14)	VAS, Liverpool elbow score	Significant pain improvement at 6 weeks. No significant difference in function.
Creaney [30]	2011	Blood was collected using a 21-G needle from the antecubital fossa into an 8.5-ml vacutainer tube with citrate anticoagulant. For patients randomly assigned to plasma injection, the blood was spun in a centrifuge at 2000g for 15 min (LC6; Sarstedt, Numbrecht, Germany) and 1.5 ml was siphoned from the buffy coat layer.	PRP vs autologous blood injection	PRP (80), ABI (70)	PRTEE	No significant difference at 6 months. Higher conversion rate to surgery in ABI group
Peerbooms [12]	2010	The patient’s own platelets were collected with the Recover System (Biomet Biologics, Warsaw, Indiana). This device uses a desktop-sized centrifuge with disposable cylinders to isolate the platelet-rich fraction from a small volume of the patient’s anticoagulated blood, drawn at the time of the procedure. Approximately 3 mL PRP was obtained for each patient. The PRP was then buffered to physiologic pH using 8.4% sodium bicarbonate, and bupivacaine hydrochloride 0.5% with epinephrine (1:200000) was added. No activating agent was used.	PRP vs steroid injection	PRP (51), steroids (49)	VAS, DASH	Significant decrease in pain and improvement in VAS and DASH scores at 1 year in PRP group (Steroid group had better initial results which declined subsequently)