As mentioned above, the expression is wrong. However, the (gramatically) correct expression "lesiรณn de trabajo" doesnt make much sense either.
The proper translation for "work injury" should be "lesiรณn laboral", though it isnt really a common expression either.
More popular related expressions are "riesgo laboral" and "accidente laboral". The latter is what I would consider the match for the english "work injury" (even not being the exact translation) and it is the one you would use when suing, which is quite a lucrative business too, so I disagree with DomainNirvana on point 4 (as well as on point 3, spanish is the only domain market close to english).
This said, I would appraise lesiondeltrabajo.com as clearly a reg fee domain, not to talk about the hyphenated version.
Good luck in future, be careful when registering non-english names, my advice is always ask for a personal translation.
PS1: For the record and for everyone: when you translate any word together with "work" used as an adjective (such as in "work injury", "work offer" and so on) it is better to use "laboral" instead of "de trabajo".
PS2: my translations apply for spanish from Spain