The radiocapitellar joint, or the lateral column of the elbow, is an important stabilizer for axial and valgus loading.1 Integrity of this joint becomes crucial to elbow stability, especially in concurrent complex elbow conditions such as terrible triad injuries, complex elbow dislocations, and longitudinal radioulnar instability.2 The radial head has been recognized as an important stabilizer of the elbow and forearm in both clinical and biomechanical studies. Radial head fractures are the most common fractures in the elbow, accounting for an estimated 25% to 44% of all elbow fractures, and frequently are associated with ligamentous and bony injuries.3
Most patients with nonreconstructible radial head fractures present with associated lesions to the elbow.4,5 When internal fixation is not feasible, the surgeon must choose between radial head excision alone or excision followed by radial head replacement to allow healing of the damaged stabilizing soft tissues around the elbow. Implantation of a radial head prosthesis (RHP) restores the lateral column and ensures both elbow stability in the coronal plane and vertical stability of the forearm.1
Radial head prostheses have a definite place in the treatment of multifragmented radial head fractures associated with instability of the elbow or interosseous ligament disruption. Polished, loose-fit, stemmed prostheses and cemented bipolar prostheses for complex radial head fractures have been reported as having excellent mid- to long-term survival.6,7 Compared with these prostheses, press-fit prostheses have been reported as having a significantly worse survival. Various studies have reported early loosening of press-fit RHPs, which often results in revision or prosthesis removal.8–10 However, recent studies have shown a relatively good clinical result. The purpose of the current study was to review the literature for studies with mixed results and report the clinical, functional, and radiographic results in patients with radial head fractures who underwent treatment with a monopolar metallic press-fit RHP.8–10
Materials and Methods
The operative database at the current authors' institution was reviewed to identify all patients who had radial head fractures that were treated via radial head arthroplasty between 2007 and 2013. The inclusion criterion was patients who underwent monopolar metallic press-fit RHP with follow-up of at least 12 months. The exclusion criterion was patients with congenital elbow deformities. A total of 11 patients with comminuted radial head fractures were treated by a single orthopedic surgeon (B.S.K.). Two patients who did not meet the inclusion criterion were excluded (1 patient underwent cemented RHP and 1 patient underwent loose-fit RHP). The remaining 9 patients, including 6 men and 3 women with a mean age of 49 years (range, 24–76 years), comprised the study population.
The dominant arm was involved in 7 patients. All fractures were Mason type III radial head fractures. Six patients had acute radial head fractures, and 3 patients had chronic radial head fractures. Associated injuries included transolecranon fracture dislocation in 3 patients, lateral collateral ligament rupture in 4 patients, medial collateral ligament rupture in 3 patients, and coronoid process fracture in 5 patients. Patients who received a prosthesis immediately after injury comprised group A (n=6), and patients who underwent a second surgery for postoperative complications comprised group B (n=3). The RHP was implanted an average of 3.5 days after injury in acute radial head fractures in group A patients (primary RHP) and 160 days from injury in chronic radial head fractures in group B patients (secondary RHP).
All fractures were deemed nonreconstructible based on preoperative imaging and intraoperative findings. All patients were treated with Ascension Modular Radial Head (Ascension Orthopedics, Austin, Texas). Approval was obtained from the institution's human research ethics board, and all patients provided written informed consent prior to enrollment in the study.
A posterior approach was used in 3 patients who had associated olecranon fractures and dislocation, and a posterolateral (Kocher) approach was used in 6 patients with isolated radial head fracture and nonunion. For deep exploration of the annular ligament, a lateral capsular incision was performed. The annular ligament was cut longitudinally, and then a position 5 mm above the biceps tuberosity was chosen for osteotomy of the proximal radius neck. After the radial head was removed, ulnohumeral articulation was identified for further release of the anterior part of the elbow. Capsulectomy and arthrolysis of the coronoid fossa were performed in some patients. After satisfactory exposure was achieved, the radial head replacement was performed.
The implant head was made of cobalt-chrome and stainless steel, and the stem was made of titanium. To insert the prosthesis, the proximal medullary canal of the radius was prepared with rasps. Subsequently, a trial prosthesis was used to check the contact between the capitulum and the prosthesis. After a suitable match of the radial medullary canal with the prosthesis was demonstrated, the final stem was implanted. The annular ligament then was repaired using nonabsorbable sutures. After the lateral collateral ligament was avulsed from the lateral epicondyle, the ligament was repaired using a suture anchor. Following reattachment of the muscles, the wound was closed in layers.
Depending on the intraoperative findings, the elbow was immobilized with a posterior long-arm splint. Five patients with associated injuries required 2 weeks of immobilization, and 4 patients required 1 week of immobilization. At 4 weeks postoperatively, unrestricted active motion was allowed.
All patients were evaluated by an orthopedic surgeon (B.S.K.) every 3 months after radial head replacement. The physical examination included goniometric measurement of motion range of the elbow and wrist, patient report of the visual analogue scale (VAS) pain score, joint stability, and the patient's degree of satisfaction. The Mayo Elbow Performance Score (MEPS) was used to categorize the results. Function also was evaluated using the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire.11
The measurement technique used to estimate the radial head implant length was based on a comparison of the radiograph of the contralateral normal elbow and the radiograph of the elbow with the radial head implant. The most recent radiographs were evaluated for sclerosis and radiolucency at the radiocapitellar and ulnohumeral joints, signs of loosening, osteolysis of the radial neck, lucency, and periarticular ossifications.12,13
Capitellar osteopenia or erosion was graded as none, mild, moderate, or severe.8 The degree of degenerative change also was graded as none, mild, moderate, or severe.13
Periprosthetic radiolucent lines around the stem were measured in millimeters using the method described by Grewal et al.14 Radiolucencies around the stem were graded as mild (<1 mm), moderate (1–2 mm), or severe (>3 mm). Bone resorption of the proximal radius was assessed and measured in millimeters between the collar of the prosthesis and bone on both anteroposterior (AP) and lateral films if the prosthesis was considered well-fixed on radiographs at final follow-up.
The lateral and medial ulnohumeral joint spaces and position of the implant stem within the canal also were analyzed to determine implant overstuffing and eccentric position. Radiographs for ulnar variance of the wrist were obtained with the shoulder abducted, the elbow flexed to 90°, and the forearm in neutral rotation.
Differences in clinical results were compared using the Mann–Whitney U, Wilcoxon matched-pair tests, and chi-square test. In all cases, P=.05 was considered to denote statistical significance.
Mean follow-up was 38.7 months (range, 12–64 months). A total of 9 patients (6 patients in group A and 3 patients in group B) were included in the study (Table 1). All of the patients were satisfied with their postoperative results. One patient reported slight pain under heavy load to the affected elbow. None of the patients required implant removal due to overstuffing, elbow stiffness, or implant loosening.
Clinical Outcome Data for Patients Treated by Radial Head Prosthesis
In all patients, range of motion was within the functional range. Average postoperative flexion was 133° for both groups, and average postoperative flexion contracture was 5° (2.5° for group A and 10° for group B). Average postoperative supination was 70° (75° for group A and 60° for group B), and average postoperative pronation was 73° (78° for group A and 63° for group B). Mean postoperative MEPS was 90 points (range, 70–100 points; 92.5 points for group A and 85 points for group B). Four patients had excellent results, 4 patients had good results, and 1 patient had fair results. Mean postoperative MEPS in group B improved from 68.3 points to 85 points. Mean postoperative DASH was 21.9 points (range, 0–61 points; 13.9 for group A and 38.1 for group B). Mean postoperative DASH in group B improved from 46.8 points to 38.1 points. Mean postoperative grip strength was 70.3% (85.5% for group A and 55% for group B) of the contralateral side.
There were no persistent instabilities at follow-up. However, 3 medial collateral disruptions in group A patients were managed nonoperatively.
Radiographs showed osteoarthritis in 3 patients in the affected elbow. This was graded as mild in 1 patient and moderate in 2 patients at final follow-up. No capitellar erosion was observed in any patient (Figure 1).
Initial anteroposterior and lateral radiographs and 3-dimensional computed tomography scan of a 24-year-old woman (patient 5) showing a comminuted radial head fracture (A). Immediate postoperative anteroposterior and lateral radiographs showing a well-centered radial head prosthesis (B). Final follow-up anteroposterior and lateral radiographs show no loosening at 62 months postoperatively (C).
Of the 9 patients, 6 experienced osteolysis within 6 months. The lucent lines around the prostheses were mild in 1 patient, moderate in 3 patients, and severe in 2 patients; the lines appeared during the first 4 to 6 months postoperatively. However, at final follow-up, the lucent lines disappeared in 1 patient with a mild lucent line and were downgraded to mild in 1 patient with severe lucent lines (Figure 2).
Initial anteroposterior and lateral radiographs and 3-dimensional computed tomography scan of a 41-year-old man (patient 4) showing a comminuted radial head fracture with transolecranon fracture-dislocations (A). Immediate postoperative anteroposterior and lateral radiographs showing a well-centered radial head prosthesis and plate fixation for transolecranon fracture-dislocations (B). Eighteen-month follow-up anteroposterior and lateral radiographs after ulnar implant removal showing lucent lines around the prosthesis and stress shielding under the neck of the radius (C). Final 60-month follow-up anteroposterior and lateral radiographs showing downgraded lucent lines around the prostheses and stress shielding under the neck of the radius and periarticular ossifications (D).
Radiographs showed signs of stress shielding osteolysis under the neck of the radius in 6 well-fixed stems; the size of the osteolysis was 3 mm in 2 patients, 2 mm in 2 patients, 1.5 mm in 1 patient, and 0.5 mm in 1 patient, which appeared during the first 4 to 6 months postoperatively. However, at final follow-up, proximal radial neck bone resorption disappeared in the patient with 0.5 mm and was downgraded to 1.5 mm in 1 patient with 3 mm (Figure 2).
Five patients experienced ectopic ossification, which was classified as grade 1. These ossifications were located at the ventral aspect of the elbow in 3 patients, the lateral capsule in 1 patient, and the medial capsule in 1 patient.
Regarding joint space measurements, the mean lateral ulnohumeral space was 2.7 mm and the mean medial ulnohumeral space was 2.9 mm. Parallelism between the lateral and medial ulnohumeral space was preserved.
On AP radiographs of the elbow, the prosthetic stem was well-centered in 8 patients and had a varus tilt in 1 patient. On lateral radiographs of the elbow, the stem was well-centered in 7 patients and had a flexion tilt in 2 patients. Centering according to both the AP and lateral radiographs was noted for 6 of the 9 implants. The mean ulnar variance (UV) was 3.6 mm (range, 2–13 mm).
Of the 9 patients, 2 patients in group B experienced elbow stiffness that was managed with ulnar implant removal and a column procedure to release the anterior capsule, as described by Mansat and Morrey.15 Ulnar impaction syndrome (UIS) occurred in 2 patients in group B. In 1 patient, the initial UV was 4 mm; 9 months later at the time of RHP, the UV had progressed to 6 mm. Subsequently, the UV increased to 13 mm 5 years after RHP; this decreased to 2 mm after ulnar shortening osteotomy was performed. The second patient underwent a wafer procedure 1 year postoperatively, and the UV was reduced from 2 mm to 0 mm. After ulnar shortening and the wafer procedure, the symptoms disappeared (Figure 3). One patient had temporary sensory deficits of the ulnar nerve.
Initial anteroposterior and lateral radiographs and 3-dimensional computed tomography scan of a 33-year-old man (patient 8) showing comminuted radial head fracture with a terrible triad injury (A). Ten-month follow-up anteroposterior and lateral radiographs after internal fixation showing metal failure and nonunion of the proximal radius (B). Immediate postoperative anteroposterior and lateral radiographs showing stem tilting in flexion; the proximal end of the RHP is distal to the ulnar coronoid process (C). Final 56-month follow-up anteroposterior and lateral radiographs showing moderate lucent lines around the prosthesis and stress shielding under the neck of the radius and periarticular ossifications (D). Final 56-month follow-up wrist anteroposterior and lateral radiographs showing ulnar impaction syndrome with an ulnar variance of 13 mm, which was corrected to 2 mm after ulnar shortening osteotomy (E).
Comparison Between Groups A and B
Results were compared between groups A (n=6) and B (n=3). Flexion contracture, forearm rotation arc, and MEPS score were better in group A than in group B. The incidence of complications, including osteolysis, was lower in group A than in group B; however, this difference did not reach statistical significance (Table 2).
Comparison of Primary and Secondary Radial Head Prosthesis
This study examined the short- to mid-term clinical and radiographic outcomes of RHP. There was reestablishment of a congruent elbow joint and elbow stability, and the results were generally good. Osteolysis was observed within 6 months, but none of the patients experienced any loosening. However, there was a high rate of complications, especially in the secondary RHP group, including 2 patients who experienced elbow stiffness and UIS.
The results of the current study correspond well with those of earlier studies. Burkhart et al7 reported mid- to long-term results of 19 patients with a bipolar radial head. The results were similar to the current results in MEPS and DASH results, as well as in range of motion, but there were 2 dislocations and 3 cases of capitellar erosion.7
In their study of 42 patients with press-fit implantation of a metallic RHP, Flinkkilä et al8 reported good clinical results with an average MEPS of 86 points after mean follow-up of 50 months. The prosthesis had to be removed in 9 cases (24%) due to loosening and associated pain.8 The implant was removed to manage elbow stiffness at the surgeon's preference even though the implant was functioning. The pooled rate of RHP removal or revision was 10%, with mean follow-up of 38 months; removal of the RHP usually occurred within 2 years after implantation.
The use of bipolar vitallium prostheses with a longer stem and cemented fixation has yielded low revision rates.16 Vitallium is a trademark alloy of 65% cobalt, 30% chromium, 5% molybdenum, and other substances. In the current study, a nonce-mented unipolar modular prosthesis consisting of a vitallium head and a titanium stem was used in all of the patients; a long stem was used in 3 cases only for the primary RHP.
Maintenance of long-term fixation and stem stability depends on multiple factors, including initial stability and the presence of an environment that promotes bone in-growth. Stem sizing is also important to achieve stable bony fixation and ingrowth. New modular designs have advantages for sizing to reproduce the anatomy of the proximal radius. Proximal fill of the canal has been known to be the most important factor affecting the initial press-fit of an RHP.17 A variety of surface treatments are available for cementless press-fit RHP stems.
Eccentric loading of the stem may cause loosening of the prosthesis. However, in a study by Moghaddam et al,10 radiographic loosening around stem prostheses did not correlate with poorer clinical results. In cases with a loose-fitting RHP where radiolucent lines are common, proximal radial forearm pain usually occurs.18 Fehringer et al19 reported radiolucencies developed in 16 of 17 patients, and proximal radial forearm pain developed in 69% of patients.
Press-fit RHP has been associated with increased loosening compared with loose stems, as they do not allow for sufficient motion to adapt to capitellum anatomy.20 Proximal forearm pain after cementless press-fit prostheses has been discussed as a strong indicator for symptomatic loosening. If symptoms and radiolucent lines are severe with the threatened integrity of the proximal radius, removal is indicated.
The reason for the relatively lower implant removal rate in the current series is unclear. One possible explanation for the low removal rate might be associated with better ingrowth. The stem design or surface coating could affect ingrowth. When the bone was rasped, cancellous bone was left when possible to enhance ingrowth. In addition, the stem design was tapered rather than cylindrical, which increased contact to cancellous bone especially in the distal area. The stem design also was symmetrical rather than curved. The torque-induced prosupination at the distal tip of the stem may be less with the symmetrical tapered design than with the curved design when osteolysis around the stem would occur before bone ingrowth. The stem material and length of the prosthesis also may affect the revision rate. In the current study, a prosthesis with a vitallium head was used in all patients and a long stem was used in 3 patients. It also is possible that arthrolysis at the time of ulnar implant removal might reduce stem bone micromotion. In the current study, osteolysis or stress shielding was improved after arthrolysis in 2 patients.
Finally, the mean patient age of 49 years in this study was relatively younger than that of 56 years reported by Tejwani and Mehta.21 The overall complication rate was higher after secondary (4 of 3) implantation than after primary (3 of 6) implantation. Katthagen et al22 reported the differences in results and complications between primary and secondary RHP are not caused at the time of implantation, but rather by the condition of the elbow. Open arthrolysis and RHP are effective in treating elbow stiffness with associated rotation limitations after resection of the radial head. However, in the current study, elbow stiffness remained in 2 patients who underwent secondary RHP and open arthrolysis; these patients achieved less forearm rotation than after primary implantation.
In the current study, UIS occurred in 2 patients after secondary RHP. Cohen et al23 reported that up to 2 mm of over-lengthening may be tolerated under simulated loading conditions without significantly increasing contact pressures of the radiocapitellar joint. In the current study, 1 patient with UIS had bone loss in the radial neck, and therefore, the RHP was relatively shorter than the ulna, which may explain the progressive proximal migration of the radius.
Combined treatment of concomitant interosseous ligament disruption and early motion are essential for successful secondary RHP. The current study reports the clinical results of RHP, which effectively restores stability and congruency of elbows with comminuted and irreparable radial head fracture and valgus laxity. Further research with longer follow-up and more cases is needed to determine whether these results are maintained in the long term.
This study had several limitations. The study was retrospective, and the number of patients was relatively small. The study included only patients with at least 12 months of follow-up to enable identification of radiolucencies, considering that osteolysis often occurs early. In addition, the variability of the associated lesions in the patient population may have affected the results.
Satisfactory outcomes were obtained using a monopolar metallic press-fit RHP for nonreconstructible radial head fractures. None of the patients required RHP removal due to overstuffing, elbow stiffness, or loosening.
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- Hall JA, McKee MD. Posterolateral rotatory instability of the elbow following radial head resection. J Bone Joint Surg Am. 2005;87(7):1571–1579.
- Hobbs DL, Mickelsen W, Wertz CI, et al. Investigating orthogonal radiography in the diagnosis of radial head fractures. Radiol Technol. 2013;85(1):102–106.
- Ring D, Quintero J, Jupiter JB. Open reduction and internal fixation of fractures of the radial head. J Bone Joint Surg Am. 2002;84(10):1811–1815. doi:10.2106/00004623-200210000-00011 [CrossRef]
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- Broberg MA, Morrey BF. Results of delayed excision of the radial head after fracture. J Bone Joint Surg Am. 1986;68(5):669–674. doi:10.2106/00004623-198668050-00005 [CrossRef]
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Clinical Outcome Data for Patients Treated by Radial Head Prosthesis
|Patient No.||Primary/Secondary||FC||FF||Supination||Pronation||MEPS||DASH||UIS||Ulnar Neuropathy||Ectopic Ossification||Stiffness||Osteolysis, mm||Proximal Shielding, mm|
Comparison of Primary and Secondary Radial Head Prosthesis
|Type of Procedure||Flexion Contracture||Supination/Pronation||MEPS||Complications|
|Primary (n=6)||2.5°||75°/78°||92.5||Ulnar neuropathy (n=1)|
|Secondary (n=3)||10°||60°/63°||85||Ulnar impaction syndrome (n=2)|