Doctor Gets Plant Thorn Arthritis

One patient's story

Medical Author: William C. Shiel Jr., MD, FACP, FACR
Medical Editor: Melissa Conrad Stöppler, MD

In a reasonable attempt to better the lives of my daughter, Cara, and son-in-law, Jim, as well as enjoy their company during a concentrated effort, I assisted them in landscaping one fine weekend day. With the primary goal of building a retaining wall and secondary goal of tidying up overgrown greenery, I attacked a palm tree grouping with pruning shears. The palm tree group of three (Phoenix roebelenii to be scientifically precise) hadn't been pruned since they moved in some two years ago. It was well overgrown and in serious need of shaping.

Picture of the Phoenix roebelenii palms with the thorn that caused the plant thorn arthritis
This is the actual grouping of three Phoenix roebelenii palms that had the thorn causing plant thorn arthritis.

Jim was industriously off at the store purchasing cement blocks, and I was in a hurry to get the pruning completed so as not slow the construction of a block retaining wall upon his return. I was wearing gloves that had extra padding over the knuckles. I finished the pruning in a timely manner and was available to help Jim unload the blocks when they arrived.

We installed the blocks regularly along a well-designed foundation that Jim and his boyhood friend Andrew built. While lifting the blocks, I felt a soreness in my right hand and at first wondered if I had strained the tendons of my fingers by pruning too rapidly. I removed the work glove on my right hand to find two thorn tips embedded in it! One was in the back of first segment (proximal phalanx) of my middle finger. The other was stuck directly in the joint at the base of the middle finger, the knuckle joint (third metacarpophalangeal joint).

A thorn on this Phoenix roebelenii measures 3 ½ inches in length.
A thorn on this Phoenix roebelenii measures 3 ½ inches in length.

I gently removed the two thorns and was hopeful that all would be well. Understand that having a thorn in tissue like the finger is usually not a serious problem. Also understand that having any remnants of thorn within a joint is a very serious problem.

Over the next day, the finger was fine, but the knuckle joint became slightly reddened. It did not hurt. The redness resolved within 48 hours and I attributed it to either blood inflammation from the trauma of the thorn, inflammation from the resin on the thorn, or both.

My hand was normal for the subsequent four days. After this "delay period," it then became stiff and swollen. At that time, a first order of concern was the possibility of bacterial or fungal infection in the joint. Accordingly, I consulted with my three partners, Catherine Driver, MD, Al Wehrle, MD, and Hernan Castro-Rueda, MD. They all agreed that I should have fluid removed from the joint immediately for culture and analysis and take an anti-inflammatory medication for pain and swelling. I also took an antibiotic until the bacterial cultures returned. Al very skillfully removed the fluid with a needle and syringe and I took it to the hospital laboratory for study. The fluid was full of an abnormally high amount of white blood cells but had no bacteria or fungus growing in it. (The actual bacteria culture takes three days and the fungus culture takes four weeks.)

When all cultures returned "no growth," because of persisting swelling and stiffness of the joint, I suspected that I had tiny thorn remnants within the joint. This is in spite of the fact that radiology imaging studies did not detect a thorn fragment. Also, the swelling of the joint did not have the appearance of what I was familiar with in cases of bacterial infection. With bacterial arthritis of a joint (septic arthritis), the joint is very hot, very red, and very painful. There is often accompanying inflammation of the adjacent skin tissues. My joint, however, was not perceptibly warm and was stiff but not really painful. These features as well as the delay period of nearly a week from the initial thorn puncture until developing the arthritis are classic features of plant thorn arthritis.