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Cactus Knee
Reported by
Myles Clough |
| A 14 year old
boy presented 24th March 1999 with inability to straighten his left knee. 3 weeks
previously while on holiday in Mexico he had fallen against a cactus which had punctured
his knee in three places on the superolateral aspect. When asked if any spines had broken
off, he was reasonably sure that none had. He was able to continue walking though his knee
swelled and hurt. He attributed that to "poison" on the spines. 5 days before I
saw him his knee locked. He was able to flex quite well and could still walk but couldn't
straighten his knee less than 40 degrees. When I saw him he was afebrile, the puncture
wounds had healed without inflammation, he had a significant effusion and wasting of the
quads and painful locking with the pain being at the medial joint line. Xrays of the left
knee were normal. I admitted him on suspicion of a medial meniscus injury having teased
out of him the notion that perhaps he did twist his knee when he fell but didn't notice it
due to the pleasure of the encounter with the cactus! As an afterthough I said to him and
his parents that I would treat an infection if I found that the penetration of the spines
had caused one. Honestly I didn't expect that; however, I did persuade the anaesthetist
that the possibility of infection did exist and that we had better do him in the middle of
the night. |
| I scoped his knee and found
this gigantic broken off cactus spine. It was about 2 cms long and 2mm in diameter. It had
broken off from the entry point in the suprapatellar region, floated round the knee then
impaled itself into the medial meniscus. There was some blood stained slightly turbid
fluid which I sent for culture. I retrieved the spine. There was none of the purulent
exudate which you see in an infected knee, although there was some hyperaemia of the
synovium. I placed suction/irrigation drains and ran 200cc saline /hour with 1 gram of
Cefazolin per 3000cc through his knee for 24 hours. I also placed him on IV Cefazolin
pending cultures. |
 |
 |
In the lateral wall of the suprapatellar pouch I could distinguish the entry point of the
spine. There was a small punture wound with a fibrinous clot hanging down from it. (Seen
at 2 o'clock in the illustration at left) This illustration also shows the degree of
hyperaemia of the synovium. The spine is shown just prior to removal below. It had been
impaled into the meniscus seen to the left and had been withdrawn into the joint to free
it up. A pituitary rongeur holding the blunt end on the spine is seen in the top of the
picture.
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Over the next 4 days he was afebrile and comfortable, taking no analgesics and wanting to
go home. The drains were removed after 48 hours. On 29th March the infectious disease
consultant told me they have cultured Aspergillus from the fluid. He advised against
antifungal agents (Amphotericin) as he thought the patient would clear it up himself now
that the contaminating spine was removed. I discharged him with review in 2 weeks at which
time I am planning to aspirate the knee, if there is an effusion, and repeat the fungal
culture. |
2 weeks later I reviewed him in the orthopaedic clinic. He had 1 cm wasting of the
quadriceps and a very small synovial effusion. There is full range flexion and about 5
degrees quads lag. He is non-tender. Considering the length of time he was symptomatic
pre-op and the period of irrigation I felt his knee showed no signs of on-going infection
or chronic synovitis. I did not repeat the aspiration. He is to undertake a physiotherapy
rehabilitation programme.At 3 month
follow-up he was asymptomatic and had normal examination and function. |
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