Table 1.

Summary of studies on human Achilles tendon rupture treatment assisted with platelet-rich plasma.

Study	Features of the Study	PRP Characteristics	Modality of Application	Outcome
Sanchez et al. [3]	Retrospective case–control PRGF and surgery n = 6 Control n = 6 only surgery	Citrate as anticoagulant Activation with CaCl2 Leukocyte- and erythrocyte-free Platelets 2–3×	Injection of 4 mL of PRGF into the suture and surrounding areas. A PRGF membrane to cover the rupture and sutured area	Faster recovery of motion, quicker return to sporting activities, and a smaller increase in cross-sectional area on tendons treated with PRGF after 18 months
Sanchez et al. [56]	Case study n = 2 Surgical repair	Citrate as anticoagulant Activation with CaCl2 Leukocyte-and erythrocyte-free Platelets 2–3×	Infiltration of 3 mL of PRGF into each tendon stump. A PRGF membrane covering the affected areas	Successful PRGF-assisted management and recovery of major post-operative Achilles tendon infection and necrosis after primary surgical repair.
Schepull et al. [14]	Randomized controlled trial PRP n = 16 Control n = 14 Surgical repair	Citrate phosphate dextrose as anticoagulant Double centrifugation Platelet concentrate Activation with CaCl2 White blood cells (WBC) unreported Platelets 10–17×	6 mL of PRP into the ruptured site through a cannula and 4 mL of PRP transdermally in the ruptured site.	No beneficial effect of platelet concentrate addition in terms of the biomechanical properties of the tendon assessed by elasticity modulus. Detrimental effect of PRP compared with control on Achilles tendon total rupture scores at 12 months.
Alsousou et al. [9]	Conservative treatment Immunohistochemical study PRP n = 10	Unreported PRP system	Locally applied PRP.	PRP promotes better Collagen I deposition, decreased cellularity, less vascularity, and higher glycosaminoglycans (GAGs) content compared with the control.
Keene et al. [12]	Randomized placebo-controlled trial PRP 113 n = 10 Control n = 116 Conservative treatment	Leukocyte-rich (LR) PRP No activation Not ultrasound-guided (US)-guided WBC 2.2× Erythrocytes Platelets 4.1×	Local anesthetic injection, then single percutaneous non-US-guided injection of 4 mL PRP into the center of the tendon gap	No functional or clinical benefit in terms of muscle tendon maximum work, limb symmetry index, heel rise endurance test, pain, and adverse effects of PRP injection compared with the placebo.
De Carli et al. [11]	Case series PRP and surgery n = 15 Control, surgery only n = 15	Leukocyte-poor (LP) PRP Liquid PRP, no activation Gel PRP, activation with thrombin and Ca-gluconate Platelets 2–3×	Addition of 2 mL of liquid PRP near the sutured tendon 2 mL of gelatinized PRP sutured to paratenon. A second injection of 4 mL of PRP 14 days post-operatively	The addition of PRP to the surgery did not offer superior clinical and functional outcomes in terms of Visual Analogue Scale (VAS) and isokinetic ankle plantar and dorsal flexor range of motion compared with the control at 6 and 24 months.
Alviti et al. [10]	Retrospective comparative study Platelet-rich fibrin (PRF) n = 11 No PRF n = 9 Healthy n = 8 Surgical repair	LR-PRP Activation with batroxobin and Ca-gluconate to generate a membrane	Application of fibrin glue over the sutured site	Almost complete restoration of the biomechanics of the gait at 6 months independently of the use of PRF or not. The PRF group showed significant improvement in efficacy of motion
Zou et al. [13]	Prospective randomized trial PRP n = 16 Control n = 20 Surgical repair	LR-PRP WBC 4× Platelets 6×	Injection of PRP into the paratenon sheath and the surrounding lacerated tissue	PRP group showed significant short and midterm improvement in the ankle range of motion, pain, stiffness, and subjective scores (Leppilahti). At 2 years of follow-up, there were no differences between the PRP and control group for these parameters.
Arriaza at et al. [8]	Case series n = 8 Surgical reconstruction	Citrate as anticoagulant Activation with CaCl2 Leukocyte-and erythrocyte-free Platelets 2–3×	PRGF injections into the quadriceps autograft as well as into the tendon stumps	Successful repair of neglected chronic Achilles tears with significant improvement in AOFAS score and Boyden functional score after 2 years of follow-up.
Kaniki et al. [15]	Retrospective comparative study PRP n = 73 Control n = 72 Conservative treatment	LP-PRP No activation Lidocaine as anesthetic Not US-guided Platelets 2–3×	One injection of 3–4 mL of PRP into the deep gap that was repeated 2 weeks afterwards with the same protocol	No measurable benefit of the addition of PRP to the conservative treatment in terms of strength or range of motion of the ankle.
Boesen et al. [57]	Randomized double-blinded prospective study PRP = 19 Placebo = 19 Conservative treatment	LP-PRP No activation US-guided Platelets 2–3× (2.5× in one sample)	One injection of PRP (4 mL) into the rupture gap that was repeated every 2 weeks to complete a total of four injections	No differences between placebo and PRP groups in term of clinical benefits assessed by ATRS score or functional outcomes at any point of follow-up (2, 3, 4.5, 6, 9, and 12 months)