[Radial head prosthesis with floating cup in recent and old injuries of the elbow: preliminary results].

PURPOSE OF THE STUDY: In recent traumatology (complex radial head fractures with severe sprain of the medial collateral ligament), as well as in sequellae (extensive release for severe elbow stiffness), the implantation of a radial head prosthesis may be necessary to stabilize the humero-ulnar joint and the radial shaft. Its major advantage consists of allowing immediate postoperative mobilization. Swanson first proposed a silastic replacement of the radial head which turned out to have serious mechanical and biological disadvantages.

MATERIAL AND METHODS: We propose a new Titanium implant, which is stiffer, and made of 2 parts connected by a spherical joint, thus maintaining an optimum congruence between the prosthetic component and the humeral condyle in any position of the joint (flexion/extension or pronosupination). This prosthesis was implanted in 4 recent fractures and reviewed after an average follow-up of 23 months [12-36].

RESULTS: Results were excellent in 2 cases, and good in 1 case: functional assessment was fair in the last case, in which the initial lesion consisted of a complex ulnar fracture associated with a Mason 3 fracture of the radial head. An osteosynthesis of the ulnar shaft and olecranon had preceeded implantation of the radial head prosthesis. In 5 additional cases with severe posttraumatic elbow stiffness, the prosthesis was implanted during elbow release, regularly allowing durable stabilization of the joint in an anatomic position, and in 2 of these cases, permanent correction of the radio-ulnar index. In these last cases, proximal migration of the radial shaft had occurred after resection of the radial head. In one case, this migration had resulted in ulnar fusion complicating a Sauve-Kapandji procedure. In the other case, proximal migration of the radius had resulted in painful distal radio-ulnar dislocation. In this second group, patients were followed-up an average of 31 months [12-46]. No complication has yet been recorded (no osteolysis, no stem breakage, no wear, no loosening).

DISCUSSION: Indications for implantation of a radial head prosthesis were deduced from these observations: in recent trauma, implantation of the prosthesis should only be indicated in those fractures, in which osteosynthesis appears not to be possible (Mason 3 or 4), with the following associations: radial head fracture with severe sprain of the medical collateral ligament--patients with positive radio-ulnar index--extensive lesions of the interosseous membrane (Essex-Lopresti, or Monteggia affecting the ulnar shaft)--associated fracture of the proximal ulna (olecranon, coronoid process...). In sequellae, we propose the following indications: extensive elbow release compromising elbow stability--painful inferior radio-ulnar dislocation complicating resection of the radial head--valgus instability complicating radial head resection.