[Radial Head Replacement: Management of Elbow and Forearm Instability after Comminuted Radial Head Fractures Associated with Elbow Dislocation].

Purpose of the study: This manuscript aims to identify an indication algorithm for the surgical treatment of radial head fractures associated with elbow dislocation. The study compares the mid-term functional outcomes of patients with multifragment radial head fracture treated by resection with the outcomes of patients treated with radial head replacement.

Material and methods: The cohort of 34 patients who sustained a radial head fracture at the mean age of 42.5 years (age range 20-81 years) was broken down into two groups by type of surgery. The EXT group consists of 20 patients with the radial head fracture treated by radial head resection. The END group includes 14 patients treated with the radial head replacement. In all patients, the radial head fracture was associated with elbow dislocation (type IV fracture according to the Mason-Johnston classification). The modified Kocher's surgical approach was used in all patients of both the groups. In the EXT group, resection of the fragmented radial head was performed. In the END group, the ExploR® Modular Radial Head System (Zimmer, Biomet, USA) was used, consisting of a CoCr (cobalt chromium) alloy head and a titanium stem. The pain and the range of motion of the elbow and forearm were evaluated after the completion of the outpatient rehabilitation (the mean follow-up period was 2.4 years). Simultaneously, the elbow joint stability was assessed. Radiographs were taken to detect heterotopic ossifications, proximalization of the radius, and any signs of prosthesis loosening. The frequency of reoperations was followed-up. The MEPS (Mayo Elbow Performance Score) was calculated.

Results: In the EXT group, the mean elbow flexion was 117.5° and the mean pronation/supination was 166.9°. In 50% of patients, the MEPS obtained was greater than 90 points, which means an excellent functional outcome. In 1 patient (5%), recurrent elbow dislocation occurred which was the reason for revision surgery (elbow transfixation with the Kirschner wires and medial collateral ligament suture). Revision surgery was also performed in 2 patients (10%) in whom not all the radial head fragments were removed. Moreover, also observed was elbow joint instability (2 patients) and temporary radial nerve paralysis (1 patient). In 1 case discrete proximalization of the radius developed. The patients in the END group showed the mean elbow flexion of 112° and the mean pronation/supination of 135°. The MEPS obtained from 69% of patients was greater than 90 points, which means an excellent outcome. The pain under load was reported by 3 patients (21%). In 5 patients (35%), the X-rays showed radiolucent zone around the stem of the prosthesis. Neither revision surgery, nor prosthesis removal has been performed yet in any patient. No instability, neurological complications or infections have been reported. In both EXT and END group heterotopic ossifications have developed in 4 patients.

Conclusions: Radial head replacement compared to the radial head resection in the management of multifragment fractures associated with elbow dislocations increase the elbow and forearm stability. The group of patients with an implanted radial head prosthesis shows a higher percentage of patients achieving excellent functional outcome than the group of patients with radial head resection.

Key words: radial head, elbow, fracture, dislocation, resection, prosthesis.