Protocol for a pragmatic randomized controlled trial evaluating a care pathway incorporating ultrasound-guided platelet-rich plasma injection plus physiotherapy versus physiotherapy alone in patients with L5/S1 lumbar disc herniation

Background: Lumbar disc herniation (LDH) causes low back pain and lower-limb neurological symptoms. Conservative and surgical treatments have similar outcomes and recurrence rates within two years. Anti-inflammatory drugs or opioids reduce inflammation but are unsuitable for long-term use. Physiotherapy improves mobility and function, but has limited evidence for reversing disc herniation. Platelet-rich plasma (PRP) is emerging as a regenerative therapy for LDH. Combining ultrasound-guided PRP with McKenzie therapy may enhance disc repositioning, tissue repair, and sustained recovery. This pragmatic trial evaluates whether adding an ultrasound-guided PRP injection pathway to standard McKenzie therapy improves clinical and neurophysiological outcomes compared with McKenzie therapy alone in a low-resource setting. In the absence of a sham control, it assesses real-world effectiveness rather than the isolated biological efficacy of PRP. Methods: This single-center, randomized controlled trial will recruit patients with L5/S1 LDH confirmed by clinical examination and MRI, following North American Spine Society (NASS) criteria. Participants will be randomized via concealed block randomization to receive PRP with McKenzie therapy or McKenzie therapy alone. McKenzie therapy, by a certified practitioner, will be delivered for 30-40 min, three times weekly for four weeks. PRP will be injected once by a spine surgeon under GE LOGIQ P5 ultrasonography. The co-primary outcomes are pain intensity and disc morphology. A hierarchical testing approach will be used, with confirmatory analysis of disc morphology performed only if the between-group difference in pain is significant (p < 0.05); otherwise, it will be considered exploratory. The study is powered for the pain outcome. Pain will be assessed using a 10-cm Visual Analogue Scale and Pressure Pain Thresholds, whereas disc morphology will be evaluated using musculoskeletal ultrasonography. Neurophysiological recovery (Straight Leg Raise, Electromyography, and Nerve Conduction Studies) and functional disability measured by the Oswestry Disability Index will be evaluated as secondary outcomes. Because participants and therapists are not blinded, subjective outcomes are susceptible to expectancy effects. Objective disc morphology is the primary unbiased endpoint. Post-tests will be obtained 4 weeks from baseline, and follow-up will be obtained after three months and six months. Significance: This study addresses a real-world evidence gap by comparing a PRP-injection care-pathway with usual physiotherapy alone. The findings will inform clinical decision-making in low-resource settings, without attempting to isolate the specific biological effect of PRP.