An orthopaedic surgical instrument assembly includes a clamp (12) comprising a first lever (20) pivotally coupled to a second lever (22). A proximal end of the first lever includes an upper handle (26) and a distal end of the first lever includes a retaining socket (28) secured thereto, and a proximal end of the second lever includes a lower handle (30) and a distal end of the second lever includes a connector (32). The assembly includes a patella drill guide and trial instrument (14) having a connector configured to be selectively secured to the connector of the clamp, a posterior trial bearing surface (52) configured to articulate with a condylar surface of a prosthetic femoral component, an anterior surface (62) opposite the posterior trial bearing surface and having a number of spikes (64) extending outwardly therefrom, and a number of drill guide holes (76) extending from the posterior trial bearing surface to the anterior surface. The assembly includes a compression socket (120) having a connector configured to be selectively secured to the connector of the clamp, the compression socket having a compressible cushion (124).
