Abstract
Periprosthetic fractures occur in approximately 1–3% of case series. Periprosthetic fractures are associated with revision surgery with difficult exposure, osteoporosis, large canal filling non-cemented stem design, overreaming of the medullary canal, and excessive external rotation with inadequate exposure. Periprosthetic fractures can be intentional when removing a well-fixed humeral stem. In this circumstance a longitudinal unicortical osteotomy along the anterior length of the stem will allow for stem and cement removal without fragmentation of the humeral bone.
Periprosthetic fractures are classified as occurring intraoperative versus postoperative as well as the location of the fracture in relation to the stem. Most intraoperative humeral fractures and all diaphyseal fractures should be x-rayed at the time of their occurrence to determine the fracture configuration, the best exposure for repair, and the length of the stem required to internally fix the fracture. Under ideal circumstances the stem should be of sufficient length to extend two cortical widths past the distal most extent of the fracture site. For fractures limited to one or both of the tuberosities, the surgical neck, or metaphyseal-diaphyseal junction, a standard length prosthetic is sufficient. For diaphyseal fractures a long stem prosthetic is necessary. In the vast majority of fractures in which the fracture fragment is displaced, open reduction and cerclage fixation with heavy suture or wire is needed. For fractures in which the proximal bone is intact and of good quality thereby providing good prosthetic fixation and rotational stability, the diaphyseal fracture can be anatomically reduced and secured with two or three cerclage wires (Dall Meyers cables or the equivalent). In this case a non-cemented long stem prosthetic is preferred. When a cemented stem is used, it is necessary to insure that cement is not extruded from the fracture site. This is accomplished by having adequate surgical exposure of the fracture, an anatomic reduction, and secure fixation before you place the cement and stem. Extruded cement may result in nerve injury or nonunion.
Intentional longitudinal fractures require direct exposure of the length of the osteotomy to control its length and displacement. It is advised to pass the cerclage wires prior to making the osteotomy. In the humerus, the osteotomy is best made just lateral to the biceps groove with an osteotome. The osteotome is placed to the depth of the stem and through the cement mantle when this is present. When the osteotomy is nearly to the length of the stem the osteotome is placed at the proximal extent of the osteotomy at approximately the mid-level of the biceps groove to a depth of the stem and then turned. This will crack the cement mantle of the opposite side of the medullary canal and open the anterior cortex. It results in a stable fracture of the humeral shaft but allows easy removal of the stem and facilitates removal of the stem from both the proximal aspect of the medullary canal and from the osteotomy site. After completion of the stem and cement removal the cerclage wires are tightened and the new stem is inserted. When secure fixation is achieved with a periprosthetic fracture, regardless of the type of fracture, the postoperative rehabilitation is the same as a routine arthroplasty and the results and time for recovery is unchanged.
Nonoperative treatment of periprosthetic fractures are reserved for the postoperative fracture occurring below the stem in a patient with a well-fixed and a functioning prosthetic, or in patients that have medical contraindication to revision surgery. A functional hinged brace can be used to help in reduction of these fractures and immobilisation of the fracture site. The braces are difficult to use and are less effective in patients with a large soft tissue envelope. Skin problems and nonunions or malunions can occur. In most cases when there is an inadequate reduction, difficult immobilisation, or stem involvement, it is best to operate soon after the fracture as late revisions in the setting of a nonunion or malunion are difficult surgical challenges.
The abstracts were prepared by Mrs Dorothy L. Granchi, Course Coordinator. Correspondence should be addressed to her at PMB 295, 8000 Plaza Boulevard, Mentor, Ohio 44060, USA.
