Radial Head Implants Research Articles

The effect of metallic radial head arthroplasty on radiocapitellar joint contact area

Objective. This study determined the effect of metallic radial head arthroplasty on radiocapitellar joint contact area. Design. The contact area of eight intact radiocapitellar joints was assessed during simulated compressive loading. Subsequently, the same experiments were repeated after reconstruction with three different radial head implant sizes. Background. There has been an increasing use of metal radial head implants relative to silicone implants. However, the contact characteristics with the metal reconstruction have not been determined. Methods. A 100 N compressive load was applied to the radiocapitellar joint at three different flexion angles for the native joint and three different sizes of a metal head implant. An impression material was employed to quantify joint contact area. Results. Following metallic radial head arthroplasty, the contact area decreased by approximately two-thirds relative to the native radiocapitellar joint ( P<0.001). Smaller implant sizes resulted in slightly larger contact areas ( P<0.05). In addition, contact area decreased as joint flexion angle increased ( P<0.04). Conclusions. Selection of radial head implant size is likely not a significant factor with regard to contact area mechanics of the radiocapitellar articulation. Relevance The effect of radial head implant size on the contact area produced with the native capitellum is not known. This study shows that the design or selection of a metallic radial head implant from the viewpoint of size is likely not an important factor with regard to minimizing joint contact stresses.

The “Terrible Triad” of the Elbow

The “Terrible Triad” of the Elbow

The functional outcome with metallic radial head implants in the treatment of unstable elbow fractures: a long-term review.

A long-term review of metal prosthetic radial head replacement in patients with radial head fractures associated with gross instability of the elbow has been performed. Twenty patients were reviewed using a modified Mayo Clinic functional rating index system. The mean follow-up was 12.1 years, with a range from 6 to 29 years. Results were excellent in 12 patients, good in 4 patients, fair in 2 patients, and poor in 2 patients. A metal radial head replacement restored elbow stability when fracture of the radial head occurred in combination with dislocation of the elbow, rupture of the medial collateral ligament, fracture of the proximal ulna, and/or fracture of the coronoid process. We conclude that a metal radial head prosthesis has select indications. We advocate its use when the radial head cannot be reconstructed in the setting of a clinically unstable elbow. Results suggest that it functions well on a long-term basis.

Early failure of silicone radial head implants in the rheumatoid elbow: A complication of silicone radial head implant arthroplasty

Three cases of early recurrent synovitis of the rheumatoid elbow following silicone radial head implant arthroplasty are presented. All three patients underwent synovectomy with silicone radial head implant for pain and loss of function due to rheumatoid synovitis. All three implants failed within 4–9 months after surgery. This failure was associated with radiographic medial joint space widening. At reexploration, recurrent synovitis with hemosiderin pigmentation was noted. Patterns of prosthetic failure included fracture, fraying, and compressive deformation or rotary wear (“motar and pestle”) of the silicone radial head; a prosthetic stem fracture was also present. Histologic examination of the synovium revealed evidence of silicone-induced synovitis; particulate, refractile silicone debris was associated with inflammatory and foreign body giant cells. The presence of rheumatoid destruction of the joint surface may have accelerated this process and may be a relative contraindiction to silicone radial head implant arthroplasty.

An anatomic and mechanical study of the interosseous membrane of the forearm: Pathomechanics of proximal migration of the radius

The interosseous membrane of the forearm of 12 fresh cadaver specimens was studied anatomically and mechanically to better understand its role in stabilization of the radius after radial head excision. A central band of ligamentous tissue, approximately twice the thickness of the membrane on either side was identified in all specimens. Mechanical studies determined the relative contribution to longitudinal stiffness of the forearm. The central band was responsible for 71% of the longitudinal stiffness of the interosseous membrane after radial head excision. The contribution of the triangular fibrocartilage complex was 8%. Silicone radial head implants were much less stiff than the intact interosseous membrane. Injury to the central band of the interosseous membrane may be crucial to the development of proximal migration of the radius after radial head excision.

Surgical Treatment of Displaced Olecranon Fractures by Tension Band Wiring Technique

Forty-five displaced olecranon fractures including 14 accompanying dislocated radial heads and seven radial head fractures were treated over a 13-year period by the tension band wiring technique. The use of supplemental internal fixation when necessary allows excellent results with the use of this technique, even in the presence of severe comminution or radial head dislocation. Primary silicone radial head implants fractured in all three patients in which they were used, necessitating repeat surgery in two patients to date. While loss of motion in terminal extension was a common aftermath of displaced olecranon fracture (59%), it was usually minor and functionally insignificant. True Kirschner-wire migration was not a common problem and can probably be eliminated by proper technique. The presence of gaps in the intraarticular surface of the semilunar notch of the ulna produced no ill effects and was compatible with excellent results. If only those cases with isolated olecranon fractures in this series are considered, there were good and excellent results in 29 of 30 cases (97%). Excision of the olecranon fragment(s) should be reserved for those cases when anatomic restoration cannot be achieved with internal fixation.

Use of acrylic prosthesis in the treatment of fracture of the head of the radius.

Use of acrylic prosthesis in the treatment of fracture of the head of the radius.