Chronic neck pain, either after trauma (e.g. whiplash injury) or due to arthritis, is a significant issue for many Canadians. Steroid injections into the small joints of the neck can provide temporary pain relief, but patients require repeat injections every few months. The investigator will assess whether a different type of injection (platelet-rich plasma, PRP) can provide enhanced and longer-lasting pain relief compared to steroid. PRP is made from the patient's own blood but contains higher levels of components that promote healing. Patients with neck pain will receive either an injection of steroid or PRP into the small joints of the neck, but they won't know which one they are getting. After the injection they will be contacted to answer questions about their pain and function, up to 12 months after injection. The goal of this study is to determine if PRP is a viable alternative to current treatments to help reduce chronic neck pain and improve function after a whiplash injury. PRP may be a more permanent treatment for chronic neck pain which could reduce the need for repeated injections, thus reducing health care costs and wait times.

The project utilizes a randomized control trial design. Ethics approval was obtained from the Western Research Ethics Board. Participants with chronic neck pain will be recruited from the SJHC Pain Clinic.

Eligible candidates who consent to study participation will be block randomized using randomizer.org into two groups (A or B). All patients will be blinded both before and after injections as to which therapy they receive. Group A will receive an intra-articular (IA) injection of autologous PRP (0.5 mL per level) and Group B will receive IA injections of corticosteroid (1.5 mL per level).

PRP: PRP preparation will occur at St. Joseph's Hospital using a standard 2-step centrifugation method. The Co-Investigator will draw 5-10cc of venous blood under sterile conditions (all patients) and subsequently centrifuge these samples at 200g for 10 minutes at room temperature. The plasma will then be separated from the sedimented erythrocytes and centrifuged again at 400g for 10 min to remove additional platelet-poor plasma. Finally, 1-2cc of PRP will be prepared for intra-articular injection. To maintain blinding, those in Group B will also have blood collection done, although their samples will not be injected.

Corticosteroid: 0.5 cc saline and 0.5cc of 10 mg/mL dexamethasone per facet joint (up to 6 mL total volume for 4 facet injections) will be prepared by the Principal Investigator or Co-Investigator.

Depending on randomization, the appropriate syringe will be delivered to the SJHC Pain Clinci interventional suite immediately after preparation. All injections will be performed by the same physician under fluoroscopic guidance at the same level(s) as the prior successful medial branch blocks. A small amount of contrast will be injected to ensure IA placement. It is recognized that IA placement may not be possible in every situation. It will be noted by the physician whether the injection is felt to be peri- or intra-articular.

Follow-up: Primary and secondary outcomes will be collected via phone or in person, pre-injection, and at 1, 3, and 6 months post-injection. If there is ongoing benefit ≥2 points on the NRS at 6 months, additional follow-up of primary and secondary outcomes at 9 and 12 months will be done.

Inclusion Criteria:

• At least 18 years old
• Facetogenic neck pain at least 4/10 on NRS after whiplash injury
• At least 50% relief of familiar neck pain after dual cervical medial branch blocks

Exclusion Criteria:

• Suspected serious spinal pathology
• Fracture/dislocation at time of injury
• Nerve root compromise
• Spinal surgery or RFN in the past 12 months
• Prior corticosteroid cervical facet injection in past 6 months
• History of any uncontrolled mental health conditions
• Other contraindications to spinal injections

The participants as well as the individuals collecting and analyzing outcome data will be blinded. The Primary Investigator, who is also the physician delivering the study compound, will not be blinded but will have no role in data collection or analysis.