Review Question - QID 219831

The patient has sustained a spiral periprosthetic humerus fracture in the setting of a stable, well-fixed humeral implant, which can best be addressed with ORIF using a hybrid locking plate and cerclage cable construct (answer choice 3).

Shoulder periprosthetic fracture management involves either ORIF or revision shoulder arthroplasty, depending on the location of the fracture and the stability of the prosthesis. Post-operative fractures often occur as a result of a fall or fatigue fracture through a stress riser; given that the tip of a stemmed humeral prosthesis acts as a stress riser, most postoperative fractures occur at or adjacent to the tip of the prosthesis stem. Fractures well distal to the stem can be treated without surgery as would any other humeral shaft fracture; however, those adjacent to the stem are at high risk for nonunion given that the prosthesis disrupts the endosteal blood supply, impairing fracture revascularization and healing. Wright and Cofield created a classification system (Illustration A), dividing peri-implant fractures into three subtypes: Type A - centered near the tip of the stem and extends proximally, Type B - centered near the tip of the stem and extends distally, and Type C - located distal to the tip of the stem. Though Type C and long spiral or oblique Type A and B fractures can be treated with immobilization and fracture bracing in the setting of stable implants, union rates have been cited as < 50%. Type A and B fractures with stable implants are more often treated with ORIF, while loose implants of any subtype should be treated with revision arthroplasty that bypasses the fracture by at least two cortical diameters.

Jonas et al. provide a case report involving the management of a periprosthetic fracture after a humeral head resurfacing total shoulder replacement. The authors note that with an aging population and a higher prevalence of osteoporosis, there is an increased risk of periprosthetic fractures. In the setting of stemmed anatomic total shoulder arthroplasty, the prevalence of periprosthetic fractures is between 1.5% and 3% and accounts for 20% of all complications; however, few reports of post-operative fractures following stemless implants have been reported. The authors concluded that fixation into the humeral head was made possible by the unique shell-like structure of the humeral surfacing component that was used.

Wright et al. reviewed humeral fractures after shoulder arthroplasty. The authors retrospectively looked at 499 shoulder arthroplasties that had been performed between December 1978 and November 1987 at the Mayo Clinic and found a total of nine humeral fractures. Six of the fractures were centered at the tip of the prosthesis, with one fracture (type A) extending proximally and five (type B) extending distally. The three remaining fractures (type C) involved the humeral shaft distal to the implant and extended into the distal humeral metaphysis. They ultimately found that three of the fractures treated with immobilization in a splint failed to heal, with two of those fractures eventually uniting after a revision of the prosthesis and bone-grafting was performed and one fracture remaining un-united post-operatively.

Figures A and B demonstrate AP and oblique radiographs of a right shoulder status post reverse total shoulder arthroplasty with a Type B, long spiral periprosthetic fracture involving the tip of the stem and extending distally, and a stable implant without gross evidence of loosening. Illustration A demonstrates the Wright and Cofield classification system. Illustrations B and C demonstrate post-operative radiographs showing ORIF with a proximal humeral locking plate and cerclage cable construct.

Incorrect Answers:
Answers 1 and 2: Though Type C and Type A/B fractures with stable implants can be treated non-operatively with success, this typically involves the use of a fracture brace, not a hanging arm cast or a simple sling, and would not be the best treatment for this patient wishing to get back to his physical activities as soon as possible.
Answers 3 and 4: Revision arthroplasty is not indicated in this patient given the stable metaphyseal prosthesis. Furthermore, an APC would not be indicated given the patient's good bone quality and lack of radiographic bone loss.