Autologous Peripheral Blood-Derived Stem Cells Combined with Platelet-Rich Plasma is Associated With Clinical and Radiological Improvement in Anterior Cruciate Ligament Ruptures—Preliminary Clinical and MRI Findings in 47 Consecutive Patients

Abstract Background Anterior cruciate ligament (ACL) ruptures are common injuries in young and active individuals and can lead to long-term functional impairment and early onset osteoarthritis. While ACL reconstruction remains the standard of care, recent evidence suggests that spontaneous healing may be possible in selected cases. Regenerative and biologic treatment concepts have therefore gained increasing interest. This study investigates the clinical and radiological outcomes of a stem cell–based regenerative treatment for traumatic ACL ruptures and presents findings as preliminary observational evidence. Methods In this single-center retrospective case series, 47 patients with isolated partial and complete traumatic anterior cruciate ligament (ACL) ruptures were treated using a biologic, non-surgical protocol. Diagnosis of an ACL rupture was confirmed by standardized clinical examination (Lachman test, anterior drawer test, and pivot shift test) and magnetic resonance imaging (MRI), which was additionally used to assess rupture morphology and synovial sheath integrity. All patients underwent an ultrasound-guided injection of autologous biologic products derived from peripheral venous blood, consisting of 8 mL of an autologous blood-derived stem cell preparation (BSC), comprising approximately 2–3 mL of concentrated mononuclear cells suspended in 6 mL of autologous platelet-containing plasma, injected directly into the torn ACL. Patients were allowed immediate full weight-bearing without bracing and followed a standardized physiotherapy program. Clinical follow-up was conducted for 12 months, including assessment of pain (VAS), functional outcomes (IKDC, Lysholm), return-to-sport timelines, and MRI-based evaluation of ligament morphology. Results The mean age of the cohort was 28.1 years (95% CI 26.0–30.2). Functional outcomes improved continuously throughout follow-up, with mean IKDC and Lysholm scores of 93.6 (95% CI 92.4–94.8) and 94.0 (95% CI 92.7–95.3), respectively, at 12 months. Pain levels decreased markedly, reaching a mean VAS score of 0.36 (95% CI 0.19–0.53). Patients returned to running after a mean of 2.19 weeks (95% CI 1.93–2.45), and most resumed their pre-injury activity level by one year. No infections or re-ruptures occurred and only one secondary ACL reconstruction was recorded. Patients with an intact synovial sheath demonstrated faster return to pivoting sports (26.8 vs. 33.2 weeks) compared with patients with a complete ACL rupture. MRI at 3 months showed evidence of improved ligament morphology in all but one patient. Conclusions This preliminary case series suggests that stem cell–based biologic stimulation may be associated with functional recovery and radiological improvement in selected patients with ACL ruptures. Prospective controlled trials are required to validate these findings.