Platelet-Rich Plasma Injection for Popliteus Tendon Rear: A Case Study

Daniel Giangrasso, DO, Jonathann Kuo, MD, Benjamin Bonte, MD, Thomas Pitts, MD, Hudson Medical, New York, NY.

A 40 year old male presented to Hudson Medical complaining of right knee pain and an acute onset of right foot drop, the inability to lift the front part of the foot. His pain and weakness reportedly began two weeks prior, after crossing his right leg over his left leg for ninety minutes during dinner. Physical examination confirmed a diagnosis of acute fibular nerve palsy, commonly presented as foot drop. Imaging of the right knee and right lower extremity revealed a ruptured baker’s cyst, active inflammation in the knee, and a tear in the popliteus tendon, which is important for unlocking the knee from a straightened position. Aspiration of the cyst did not provide pain relief or improvement in foot drop. Electromyography (EMG) results were consistent with a deep injury to the peroneal nerve, which normally controls the muscles involved in lifting the leg.

While acute foot drop is most often caused by a direct injury to the peroneal nerve, it appeared that the combination of the ruptured baker’s cyst and the ruptured popliteus tendon contributed to a hematoma, which compressed the peroneal nerve. Direct compression of the nerve while crossing his legs also likely contributed to the acute onset of foot drop.

The patient underwent a platelet-rich plasma (PRP) injection into the right popliteus muscle and was also given an electrical muscle stimulation unit programmed to help treat symptoms of foot drop. Patient was also instructed to begin a course of physical therapy.

At 2 weeks post-PRP injection plus physical therapy, the patient reported improvement in his pain but still complained of foot drop symptoms.  At 8 weeks, the patient admitted to complete resolution of knee pain and foot drop. Patient was able to compete in his surfing competition.

The results of this study suggest that acute right foot drop can be multifactorial. Aspiration of hematoma, avoidance of aggravating factors, and soft tissue repair with PRP led to complete resolution of acute foot drop.