MRI‑guided neurolysis for the treatment of chronic refractory knee pain: a novel technique

Chronic refractory pain poses a significant challenge in knee joint pathologies, especially after exhaustion of conservative, arthroscopic, and endoprosthetic therapy options. This case report by Alexander W. Marka et al illustrates an innovative approach using MRI-assisted chemical neurolysis of a genicular nerve to manage persistent knee pain after arthroscopy.

The authors opined – “MRI guidance can facilitate the targeting of nerves that are traditionally more challenging to approach, such as the inferolateral genicular nerve, which is often spared due to its proximity to the common peroneal nerve, and the patellar branch of the saphenous nerve. By providing clearer visualization of these nerves, MRI guidance could expand the range of treatable targets, leading to more comprehensive and effective pain management strategies.”

The CASE

A 62-year-old male had been experiencing chronic knee pain for several years, which was attributed to deep cartilage damage on the medial condyle, as shown by MRI and confirmed by arthroscopy. Despite undergoing matrix associated autologous chondrocyte transplantation (MACT), the patient continued to experience persistent pain in the inferomedial aspect of the knee. The pain (8/10 on a numeric rating scale (NRS) for pain) was exacerbated in knee flexion and accompanied by peripatellar tension. The patient reported significant impairment of daily activities, especially while walking stairs, leading to a reduction of quality of life and limitation of rehabilitation training.

After unsuccessful attempts to manage the pain through a multidisciplinary approach, including physiotherapy and infiltration with local anesthesia and corticosteroids, the patient was referred for further evaluation and management.

The authors performed a high-resolution planning MRI (acquisition time: 5:30 min, slice thickness: 2.5 mm, in-plane resolution: 0.33 × 0.29 mm, acceleration technique: compressed sensing with a sense factor of 6 and deep learning based reconstructions) of the knee to visualize the genicular nerves innervating the knee capsule.

The procedure was conducted using a standard 3 T MRI scanner, with a routine diagnostic MRI slot blocked off for approximately 30 min. No dedicated procedural MRI suite was required. They used MRI-compatible equipment, including non-ferromagnetic needles, to ensure safety within the MRI environment. The procedure involved precise nerve localization using high-resolution MRI, followed by realtime guided administration of the neurolytic agent.

After obtaining informed consent, the exact location of the inferomedial nerve was targeted for chemical neurolysis. For this, limited-coverage navigating scans were used (acquisition time: 33 s, slice thickness: 3 mm, in-plane resolution: 0.33 × 0.29 mm, acceleration technique: compressed sensing with a sense factor of 3 and deep learning-based reconstructions). Initial injection of 1 ml Bupivacaine 1% confirmed the patient’s pain reduction without any impact on muscular function.

The patient returned the following week for a targeted ethanol neurolysis procedure, during which 1 ml of 97% ethanol mixed with 0.5 ml of Bupivacaine was administered. Postprocedural STIR images confirmed that ethanol deposition.

After the procedure, the patient reported significant pain reduction (8/10 -> 1/10 on an NRS) which persisted until the end of follow-up after 4 months (1/10 on an NRS). While there was still a feeling of slight peripatellar tension, the knee function, especially the ability to climb stairs, was regained.

The authors opined – “Further studies are needed to explore the long-term outcomes and safety of this treatment in larger populations. While this case report provides initial insights into the potential benefits of MRI-assisted chemical neurolysis, more comprehensive data is required before considering its inclusion in management algorithms for refractory knee pain.”

Further reading:

MRI‑guided neurolysis for the treatment of chronic refractory knee pain: a case report

Alexander W. Marka et al

Skeletal Radiology

https://doi.org/10.1007/s00256-024-04819-9