Chapter 10 Hinged Dynamic External Fixation of the Elbow
Surgical Overview
• Dynamic hinged external fixation offers a solution for cases that responded poorly to other methods of contracture release. It is defined as a hinged device that separates and distracts the ulna from the humerus while providing varus and valgus stability to the elbow. The hinged fixator allows active and passive motion of the elbow joint and stretches the soft tissue capsule at the end range of both flexion and extension.
• Currently, two dynamic hinged fixators are widely used: the Mayo dynamic joint distractor and the Hotchkiss compass hinge.
• Use of a dynamic fixator may be indicated in several situations, including acute trauma with complex instability, recurrent instability after collateral ligament release, contracted stiff elbow that is mature and has failed conservative therapy, extreme tightness in the muscle tendon unit following a capsular release, and posttraumatic arthritis of the elbow.
• Following a contracture release, the hinged device is applied to maintain the ROM gains achieved intraoperatively and provide elbow stability if it was compromised during the contracture release surgery.
• Application of the hinge allows scar tissue to remodel in an environment that permits joint distraction, joint stability, joint motion, and promotes the healing of the articular surface.
• Through smooth, progressive adjustments of the device while in its locked position, the soft tissue is maintained at its available end range. Motion is performed to condition the muscles with the hinge unlocked.
• Once the underlying pathology has been addressed via contracture release or resurfacing of the joint, the hinge is applied. In most trauma cases, a posterior incision is made and the joint is exposed medially and laterally, depending on the pathology.
• For a stiff elbow both a posterior and an anterior incision may be required for a complete capsular release.
• A temporary axis pin is placed through the distal humerus to align the hinge with the axis of rotation.
• Two humeral pins (medial and lateral) are placed to secure the humerus in two planes. Two pins are placed in the ulna anterior and posterior to the axis of rotation.
Rehabilitation Overview
• Dynamic hinged fixators are used following complex elbow dislocation, traumatic elbow fracture, and complex contracture release.
• Despite the various indications for placing a dynamic hinge, the role of the hinge is always the same, that is, to stabilize the joint and permit immediate postoperative movement.
• The therapist must communicate with the surgeon and obtain the details of the original injury and the operative procedure, and confirm an appropriate plan of care.
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