Upper Arm Fracture After Shoulder Replacement
With the increasing number of total shoulder replacements, periprosthetic (near the implant) fractures are more likely. In this article, surgeons from Mayo Clinic review the types of fractures that can occur in the humerus (upper arm bone) after shoulder replacement and their treatment.
The risk of periprosthetic humerus fractures is increased with any of the following risk factors:
Revision arthroplasty refers to a second operation after the first or primary shoulder replacement. Cement used in the first operation can make it more difficult to repair or replace a loose or broken implant. Soft tissue contractures (adhesions or scar tissue limiting motion) may also complicate revision procedures.
Fractures may be above, just at, or down below the tip of the implant stem. Delayed healing or failure to heal is called nonunion. Nonunion is more likely when blood supply is disrupted. Increased force passing through the fracture site is another reason why the fracture doesn't heal quickly or properly.
Treatment depends on how bad the fracture is. If the two ends of the bone have not separated, then it is considered nondisplaced. This type of break can be treated with a fracture brace. If the fracture still doesn't heal after using a brace, then surgery may be needed. Surgery may not be possible if there is infection or medical problems preventing the use of general anesthesia.
If the stem of the implant down into the humeral shaft is loose, it must be removed and replaced. A longer stem (one that extends past the fracture site) is needed. Sometimes additional metal plates, wires, and/or screws are used to help stabilize the fracture site. This is called rigid fixation with instrumentation.
The authors discuss various types of surgical repair for humeral fractures. The choice may depend on whether or not the fracture occurred during or after the initial shoulder surgery. Likewise, the type of fracture makes a difference (above, at, or below the tip of the implant stem).
Specific patient positions and surgical approaches are presented. Some of these decisions are based on the location of the fracture. Care must be taken to avoid further nerve damage when inserting drills, plates, screws, and wires.
Rehab after surgery to foster early motion of the shoulder and elbow is often advised. The surgeon decides on the best postoperative course of action. Some of this depends on how stable are the implant, repair, and soft tissues around the fracture and shoulder. The quality of bone makes a difference, too. Active motion is allowed when there is X-ray evidence of fracture healing. This takes about six weeks but may be delayed by several months.
The authors offer suggestions for surgeons to prevent periprosthetic humerus fractures. Being aware of the risk factors is the first, and most important, step. Releasing the shoulder capsule and any soft tissue adhesions will help reduce the risk of fracture.
The shoulder and arm must be moved during surgery carefully to avoid dislocation or further fracture. X-rays should be taken in the operating room to make sure no further damage has been done. Specific surgical techniques such as endosteal notching and hand reaming are also outlined. Proper patient positioning is reviewed.
References: Scott P. Steinmann, MD, and Emilie V. Cheung, MD. Treatment of Periprosthetic Humerus Fractures Associated with Shoulder Arthroplasty. In Journal of the American Academy of Orthopaedic Surgeons. April 2008. Vol. 16. No. 4. Pp. 199-207.
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