Disclosures: Daniel T. Kuo, DO: Nothing to disclose

Case Description: The patient presented with 14 months of right foot pain after a fall. MRI revealed grade 1 strain of the extensor digitorum brevis and abductor digiti minimi, and complete plantar plate tear at the 3rd MTP joint. She had previously tried PT, bracing, and cortisone injections around the extensor tendons without relief. Exam demonstrated tenderness at the base of the 4th-5th webspace. A solution of 0.4 mL of dexamethasone (10mg/mL) and 0.5 mL of 1% lidocaine was injected into the right 4th-5th metatarsal base using ultrasound guidance. Patient reported complete relief for 1month following the procedure. Review of her MRI revealed a small signal abnormality within the interossei muscle at the proximal insertions concerning for a small interstitial tear. Repeat injection with 0.5 mL of 5% ropivacaine was used to confirm diagnosis after which patient elected to proceed with plasma-rich platelet (PRP) therapy. Preparation of the autologous PRP was performed using an EmCyte PurePRP® closed centrifuge system. A peripheral blood volume of 30 mL yielded 3 mL of leukocyte-rich PRP. Under ultrasound guidance, a mixture of 1% lidocaine and 0.25% bupivacaine was used for local anesthesia, followed by injection of the plasma concentrate into the right 3rd-4th and 4th-5th interossei muscles and tendons.

Setting: Private orthopedic practice.

Patient: A 45-year-old female with chronic right foot interossei tendinopathy.

Assessment/Results: At 6 weeks post-injection, the patient reported 1/10 pain on the numeric rating scale (NRS) and 80% symptom improvement. At 12 weeks post-injection, the patient reported 0/10 pain on the NRS. Exam unrevealing for tenderness over the 3rd-4th/4th-5th webspace. Patient was able to return to the gym without any recurrent symptoms.

Discussion: This is the first reported case, to our knowledge, of interossei tendinopathy that was successfully treated with PRP therapy.

Conclusion: Autologous PRP therapy maybe a potential treatment alternative for chronic interossei tendinopathy that is unresponsive to traditional conservative measures.

Level of Evidence: Level IV

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/treatment-of-chronic-foot-interossei-tendinopathy-with-platelet-rich-plasma-a-case-report/