PHILOS stand for Proximal Humerus internal locking system. It is an anatomic fixation system for the proximal humerus which also provides angular stability. This plate was designed with an eye on eldery people as their bones are osteoporotic. A fixation with this system provides stability and reduces the number of complications.
It is a precontoured plate and broader on the proximal part than distal. Here is an image of the system.
Proximal Humerus Internal Locking System is used for fixation of upper humeral injuries and is indicated in
- Dislocated two-, three-, and four-fragment fractures of the proximal humerus, including fractures involving osteopenic bones
The plate comes in two lengths. One is 90 mm long and has 3 holes. Long PHILOS has a length of 140-270 mm and contains 5, 6, 8, 10, and 12 elongated holes in the shaft.
It has 9 proximal screw holes. It is available in pure titanium and implant steel.
The plate is contraindicated in acute infections and children during the growth phase.
The proximal Humerus Internal Locking System is put using deltopectoral or transdeltoid approach after temporary reduction and fixation with sutures and k-wires.
The plate is positioned at least 8 mm distal to the upper end of the greater tubercle. Roughly it is the insertion od rotator cuff. Placing the plate at too high a level increases the risk of subacromial impingement. Placing the plate too low can prevent the optimal distribution of screws in the humerus head.
Therefore it is pertinent that PHILOS is placed well. Also, the plate is centered laterally against the greater tubercle, ensuring that a sufficient gap is maintained between the plate and the long biceps.
If PHILOS is not available standard plates like modified cloverleaf plate are an option though there is some evidence that angular stable plate provides better outcomes.
The fixation provided by PHILOS is strong and allows early mobilization of the affected joint.