The man was left with injuries to his face following an attack on on August 17 at around 6pm on the pathway from Straiton Pond to the Loanhead Railway Path.
The Scottish Ambulance Service attended the scene and the man was taken to the Edinburgh Royal Infirmary for treatment.
Police are now appealing to the public for information regarding this incident.
Police Sergeant Bryan Jones said: “This man sustained a painful injury and we are eager to establish the full circumstances of this incident.
“Anyone who was in the Straiton Pond area last night and saw anything relevant to our enquires is asked to contact police immediately.”
Those with information can contact Police Scotland on 101 or anonymously through Crimestoppers on 0800 555 111