Management of radial head fractures with implant arthroplasty

Pyrocarbon unipolar radial head prosthesis: clinical and radiologic outcomes at long-term follow-up

BACKGROUND

Several studies have already reported good short-term results with a pyrocarbon unipolar radial head prosthesis (Pyc-uRHP). The aim was to evaluate the evolution from mid- to long-term clinical and radiographic outcomes of a Pyc-uRHP.

METHODS

This was a retrospective, single-center study. We followed up all the patients who underwent Pyc-uRHP surgery in our original study at 2 years of follow-up (52 patients), reaching a minimum of 7 years of clinical and radiologic follow-up. This study included 26 patients who underwent a clinical examination assessing mobility, the Mayo Elbow Performance Score, and the visual analog scale score and radiologic evaluation with anteroposterior and profile radiographs at a mean follow-up of 110 months (range, 78-162 months). The radiologic study analyzed signs of proximal osteolysis, stem loosening, capitellar wear, and humeroulnar osteoarthritis.

RESULTS

No patients required revision. Eight patients required reoperation: coronoid screw removal in 1 and arthrolysis for stiffness in 7. The mean time to reoperation was 11 months. The mean Mayo Elbow Performance Score at last follow-up was 96 ± 9 (of 100), with a pain score of 42 ± 7 (of 45), mobility score of 19 ± 2 (of 20), stability score of 10 (of 10), and function score of 25 (of 25). Comparison with clinical data from the mid-term delay did not reveal any significant difference. All patients presented with proximal osteolysis around the neck but without progression. No stem loosening was noted. The rates of humeroulnar osteoarthritis (12% at mid-term vs. 80% at last follow-up, P < .0001) and capitellar lesions (34% at mid-term vs. 80% at last follow-up, P = .001) increased significantly.

CONCLUSION

We have shown that a Pyc-uRHP at 9 years' follow-up provided stable and satisfactory clinical results. Osteolysis of the radial neck was always present but it did not evolve, and no stem loosening was noted. Finally, we have shown a clear worsening of radiologic humeroulnar osteoarthritis and capitellar lesions that remained asymptomatic.

The Effect of Radial Head Hemiarthroplasty Geometry on Proximal Radioulnar Joint Contact Mechanics

PURPOSE

To compare the joint contact area and peak contact stress of different radial head (RH) hemiarthroplasty articular profiles for the proximal radioulnar joint (PRUJ) to the native radial head with the hypothesis that the side radius and side angle closest to the native mating ulnar articular profile would provide the best contact mechanics.

METHODS

Finite element models generated from the computed tomography geometry of 14 native elbows (73 ± 17.5 years) were subjected to 12 different RH profiles having varying side radii (flat [r = ∞ mm], 16.25, 8.12, and 4.50 mm) and side angles (0°, 5°, and 10°) under a constant compressive 20-N medial load. Contact areas and peak contact stresses were computed and compared with the native joint.

RESULTS

On average, RH implants significantly reduced PRUJ contact area by 55% ± 16% and increased peak contact stress by 337% ± 241% compared with the native RH. The prosthesis side radius had significant effects on both contact area and stress, but side angle did not. The 16.25-mm radii produced the largest contact areas, and the 4.50-mm radius model generated the smallest contact areas. As the side radius was decreased, peak contact stress was reduced as the contact migrated toward the center of the native ulnar articulation, although the 8.12-mm radius achieved the lowest peak contact stress.

CONCLUSIONS

Whereas RH hemiarthroplasty side radius can affect both contact area and peak contact stress, the magnitude of the effect on contact area is relatively small compared with that of the peak contact stress. Furthermore, although a flat RH side profile with a side angle of 5° more closely matched the side profile of the native ulnas used in the present study, the optimal profile was found to be a smaller radius of 8.12 mm.

CLINICAL RELEVANCE

Optimizing PRUJ contact mechanics after metallic RH hemiarthroplasty may contribute to better clinical outcomes by reducing the potential for native cartilage degeneration.

Clinical and radiologic outcomes of pyrocarbon radial head prosthesis: midterm results

BACKGROUND

The modular pyrocarbon (MoPyC) radial head prosthesis (Tornier, Saint-Ismier, France) is a monoblock modular radial head prosthesis. This study assessed midterm outcomes after implantation of the prosthesis.

MATERIALS

A retrospective study was conducted of a consecutive cohort of 65 patients who underwent radial head replacement with the MoPyC prosthesis from January 2006 to April 2013. Indications were fractures, early or late failures from orthopedic or fixation treatments, and revisions after another implant. Patients were observed for >2 years for range of motion, pain, and stability; function by the Mayo Elbow Performance Score (total score, 100) and grip strength were assessed. Quality of stem implantation, bone resorption around the neck, and periprosthetic lucency were noted and quantified on radiographs. Capitellum shape and density as well as humeroulnar aspect (river delta sign) were evaluated. Complications and revision procedures were noted.

RESULTS

We evaluated 52 of 65 patients (mean follow-up, 46 ± 20 months; range, 24-108). The Mayo Elbow Performance Score was 96 ± 7; pain score, 42 ± 7/45; and motion score, 18 ± 2/20. Function and stability were excellent. Radiology revealed 92% of patients with cortical resorption around the neck without mechanical failure. Bone resorption was mostly anterior and lateral; it resolved within the first year and thereafter was stable. Eight patients underwent revision surgery for stiffness. No implant failures were noted.

CONCLUSION

Results of the MoPyC radial head prosthesis appear to be satisfactory. Bone resorption around the neck (stress shielding) is frequent and stable after 1 year and does not impair stem fixation. The MoPyC prosthesis appears to be a reliable solution for replacing the radial head.

Contact analysis of the native radiocapitellar joint compared with axisymmetric and nonaxisymmetric radial head hemiarthroplasty

BACKGROUND

Radial head (RH) implants are manufactured from stiff materials, resulting in reduced radiocapitellar contact area that may lead to cartilage degeneration. Although the native RH is nonaxisymmetric, most implants are axisymmetric, potentially contributing to altered contact mechanics. This study compared the joint contact area (Ac) and maximum contact stress (σmax) of axisymmetric and nonaxisymmetric RH implants to the native radiocapitellar joint.

METHODS

The contact mechanics of intact elbows derived from cadaveric computed tomography data (n = 15) were compared with axisymmetric (size: 18, 20, 22 mm) and nonaxisymmetric (size: 16 × 18, 18 × 20, 20 × 22 mm) RH hemiarthroplasty reconstructed elbows using Abaqus finite element software. Under a 100 N load, Ac and σmax were computed for ±90° pronation-supination and 0°, 45°, 90°, and 135° flexion.

RESULTS

Compared with native, both hemiarthroplasty models produced significantly lower Ac and higher σmax (P < .001). In the best orientation, the nonaxisymmetric RH provided significantly larger Ac at 0° and 135° flexion (P = .03, P = .007) and reduced levels of σmax at 45° and 90° flexion (P = .003, P < .001). However, there was also a worst orientation that reduced Ac and increased σmax for all flexion angles (P < .003 for all). The native RH was less sensitive to rotation than the nonaxisymmetric RH in terms of σmax (P < .001). The axisymmetric RH was not sensitive to rotation.

CONCLUSIONS

Whereas a nonaxisymmetric RH can provide improved contact mechanics at certain forearm rotations and flexions, there are also orientations where Ac is reduced and σmax is increased. Axisymmetric designs are more consistent throughout forearm rotation and therefore may be more forgiving than the nonaxisymmetric RH implant design used in this study.

Surgical management of elbow dislocation associated with non-reparable fractures of the radial head

BACKGROUND

The "terrible triad" of the elbow is the combination of an elbow dislocation, radial head and a coronoid process fracture. Because of a combined sagittal, frontal and transverse instability, these injuries are notoriously difficult to treat. We report our results with a technique for reconstruction of "terrible triad" injuries with either no facture or a type I fracture of the coronoid process in addition to a non-reparable radial head fracture. The hypothesis of this study was that standard surgical treatment of this lesion using a "deep to superficial" stabilisation by a single lateral approach and radial head replacement enables early and reliable functional results.

PATIENTS

From June 2004 to January 2007, 13 patients with an average age of 40 years at the date of trauma (range 18-77) underwent reconstruction of a "terrible triad" injury of the elbow with the same technique. The mean follow-up was 25 months (range 15-48).

RESULTS

Eighty-four percent of the patients were very satisfied and satisfied. Average flexion was 131 degrees (110-140). Average extension was -11 degrees (-30-0). Average pronation was 72 degrees (40-80). Average supination was 70 degrees (50-80). The grip strength averaged 75% of that of the non-injured side (50-105). All elbows were stable at review. Eight complications occurred.

CONCLUSION

Our results suggest that some terrible triad injuries can be successfully managed with deep to superficial stabilisation by lateral approach, consisting in three-dimensional stabilisation done by anterior capsular reinsertion with absorbable anchors, radial head replacement and lateral collateral ligament repair. This standard management provides enough stability to allow early active rehabilitation, preventing post-operative instability and stiffness. This procedure appears to be reliable and reproducible.

Arthroscopic treatment of fractures of the radial head

An original technique for the arthroscopic diagnosis and treatment of the fractures of the radial head is proposed and described. The elbow arthroscopy is started with a 4.5-mm 30 degrees arthroscope from the proximal anteromedial portal and the anterior elbow is examined; then a proximal anterolateral portal is created and a full-radius blade inserted to take out the hematoma and to allow visualization of the radial head that is explored through the whole range of motion to visualize the fracture fragment. The fragment is manipulated by means of arthroscopic tools to reduce the anteromedial surface of the radial head. The arthroscope is now switched to the posterolateral portal and the posterior aspect of the humeral radial joint is visualized. The soft spot portal is used to insert a periosteal elevator to complete the reduction and firmly hold the fragment in the reduced position. An anterolateral portal is now created to allow the safe insertion of a guidewire, angled 45 degrees to the longitudinal axis of the radius, to pierce the fragment with. A 14-mm long cannulated screw is inserted along the guide after specific drilling. Finally, the reduction and the stability of the fixation are checked with during full rotation of the elbow. The described procedure has been performed in 6 patients. Short-term preliminary results show a satisfactory functional outcome. Among the advantages of the technique are the minimally invasive approach, the direct visualization of the fracture, and the benefits derived from the radiation-free procedure.

Radial head arthroplasty

Radial head fractures are a particularly common yet challenging problem facing orthopedic surgeons today. Over the years multiple treatment modalities have been used including conservative management, open reduction and internal fixation, head excision, and radial head arthroplasty. The clinical outcome studies of metallic radial head arthroplasty systems indicate that head replacement is a reasonable option to offer patients with comminuted radial head fractures and complex elbow trauma. Overall the results for this procedure are quite encouraging and appear durable given the severity of the elbow injuries treated with radial head arthroplasty. This article discusses the history, classification, and treatments of radial head fractures. A description of the stabilizing structures of the elbow as they relate to radial head fractures also is included. Surgical considerations that relate to radial head arthroplasty are detailed and encompass arthroplasty indications, surgical technique, postoperative rehabilitation, and complications. Finally the arthroplasty outcomes literature and a review of current implant options also are discussed.