Can Milwaukee shoulder present with a large subacromial bursitis, or does it predominantly cause joint effusion/destruction?

This is an interesting question. Milwaukee shoulder is primarily considered an arthropathy due to basic calcium phosphate crystals (Halverson et al., PMID 2155593). So the effusion will be seen in the joint, but because of secondary damage to the capsule and rotator cuff, it will typically extend into the subacromial bursa as well. I do not know of any cases where the bursa is involved without the joint also being involved. However, calcific tendinitis of the rotator cuff can produce a subacromial bursa effusion without a GH joint effusion. It is also secondary to calcium crystal deposits but does not typically cause a bloody effusion or rapid tendon and bone lysis like Milwaukee shoulder can.