MONOARTICULAR SYNOVITIS OF KNEE DUE TO UNRECOGNISED INTRA-ARTICULAR PLANT SPLINTER

Introduction :

Monoarticular synovitis of knee secondary to penetrating splinter injuries of plant origin are rare but a well described entity which is usually under-recognised.1,2,3 This is apparently is due to the trivial nature of trauma and a very insidious onset of symptoms. The effusion may be sterile and is due to the irritation of the foreign body to the synovial tissue3, 4 but occasionally organisms may be isolated.5

Radiographs may be negative and MRI may show synovitis without a specific pathology.6

Arthroscopy is the most important diagnostic and therapeutic procedure along with radiographic examination in a case of suspicious history and clinical features.7

Case Report:

A 59 year old gentleman presented to us with alleged history of penetrating trauma at a bamboo plantation site when accidentally his sickle cut a wound over the anterior aspect of the knee one month ago. The wound had healed within two weeks without any complications but the knee pain and swelling which gradually progressed with disturbing his daily activities and sleep. He complained of throbbing type of pain, which was not relieved with analgesics and rest. He had no history of fever or chills or any other joint involvement.

He was clinically assessed and effusion was noted at the knee joint (Figure 1), with a fixed flexion deformity and terminally painful range of motion with local rise in temperature. The routine haematological evaluation was normal (total count: 9200, CRP: Negative) and no infectious pathology could be recognised.

X-ray was within normal limits with early features of osteoarthritis. MRI images showed significant effusion in the knee. Diagnostic arthroscopy of the left knee was performed under spinal anaesthesia. There was pale yellow colour clear synovial fluid about 120ml which was drained and sent for evaluation (Figure 2). Synovial tissue was inflamed with features of unhealthy fimbriae. A brown coloured 3-4 mm long slender foreign body was identified in the medial joint space overlying the meniscus (Figure 3) and was extracted (Figure 4). No other foreign bodies were recognised on probing the joint. Near total synovectomy of the knee was done.

Closure of the surgical site was done.

The synovial fluid analysis revealed, normal sugar and proteins. The culture reported no growth in the fluid sample. Intravenous antibiotics were stopped at five doses.

Knee exercises were started immediate post op and full range of motion was attained in two months and the operated knee appeared normal like the contralateral knee on review (Figure 5).

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Figure 1

Left knee showing suprapatellar and parapatellar effusion.

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Figure 2

Pale yellow synovial fluid drained from the knee.

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Figure 3

3-4 mm long slender foreign body identified in the medial joint space overlying the meniscus.

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Figure 4

4 mm long slender foreign body after removal from the knee.

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Figure 5

At 6 weeks post-op the operated knee appears normal just like the contralateral knee

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Discussion and Review of Litrature:

Arthritis caused by plant thorn penetration is well known, especially among children. Blackthorn or date palm thorns caused synovitis is reported in most cases8, but it can occur from thorns of several kind of plants9,10,11. The most commonly affected joint is the knee, but similar processes have been described in the hand, ankle, and wrist9,10,12,13.

Historically, failure to discover an organism in the joint fluid after a plant thorn injury led to the hypothesis, first published in 1953, that the synovitis after these injuries was an aseptic inflammatory reaction provoked by alkaloid compounds in the vegetable matter14. This disease at that time was known as “blackthorn inflammation” 15.

It was not until 1977 that the first positive culture specimen of synovial fluid after plant thorn injury was reported with growth of Staphylococcus albus, Streptococcus hemolyticus, and Gram-negative rods16. Joint infection caused by Pantoeaagglomerans was first reported in 197817.

In earlier reports, treatment consisted of arthrotomy and removal of all thorn fragments14,15,16. In 1980, the advantages of arthroscopy became clear18. Arthroscopy may allow complete observation of the joint and extraction of the foreign body, but there still are several pitfalls. Plant fragments usually are too small to be seen and a reactive hypertrophic plica can obscure the presence of an intraarticular foreign body and may be missed by the operating surgeon7. This led to the recommendation to remove all the macroscopically abnormal synovial lining. In most instances, this will involve complete synovectomy or recurrence of symptoms is possible1,7,10,16,19. O'Connell RL, Fageir MM, Addison A reported a case of synovitis of the knee due to trauma by a splinter of wood and also removal of the splinter by mini-arthrotomy20. Díaz-Martín AA et al; reported a case of arthroscopic removal of a projectile from the knee after a gunshot wound to the knee.21 Joris F. H. Duerinckx reported a case of subacute synovitis of knee after a rose thorn injury21. Muschol M, Drescher W, Petersen W, Hassenpflug J published on ‘Monarthritis of the pediatric knee joint: differential diagnosis after a thorn injury.’ Wherein the misdiagnosis of a foreign body of knee was made as monoarthritis and arthroscopic removal of the foreign body was done after confirming the diagnosis7.