Metallic Radial Head Research Articles

Anthropometric Study of Proximal Radius in Below-Average Height Thai Women and Its Correlation with Commercially Available Radial Head Prostheses.

Background: Most radial head prostheses were designed in Western countries based on the anatomical characteristics of Western populations. We hypothesised that these prostheses are too large for below-average height Thai women. The objective of this study is to evaluate the anthropometric parameters of the proximal radius in such a population and its correlation with commercially available prostheses. Methods: Dominant elbows of 124 Thai women whose height was <155 cm were studied. Using the standard anteroposterior and lateral radiographic images, the head diameter and thickness, the distance between the articular surface and radial tuberosity, the narrowest intra-medullary canal diameter and the narrowest outer diameter of the radial neck were measured. Correlations between body height and each radiographic parameter were assessed using the Pearson correlation coefficient (PCC). The specifications of the commercial metallic radial head implants were reviewed and used to evaluate the relevant radiographic parameters. Results: Mean of the minimum and maximum head diameter was 18.54 ± 1.11 mm and 19.13 ± 1.17 mm, respectively; the thickness was 7.43 ± 0.69 mm, the distance between the articular surface and tuberosity was 19.05 ± 1.45 mm, the intra-medullary canal diameter was 7.63 ± 1.2 mm and the outer diameter of the radial neck was 11.13 ± 1.26 mm. There is a poor correlation between the participant's height and each parameter (PCC ≤ 0.50). In 24.2% of the participants, the smallest size of prosthetic designs with a head diameter of 20 mm is larger than +2 mm in reference to minor diameter. The minimum prosthetic head thickness is greater than the average value of the participants in 12 out of 15 designs. One participant has an outer neck diameter smaller than the smallest stem diameter of three designs. Conclusions: Surgeons must be aware that commercially available radial head replacement implants may be too large for below-average height Thai women. Level of Evidence: Level IV (Prognostic).

Clinical long-term results of radial head arthroplasty in comminuted radial head fractures.

Modern radial head prostheses have recently become more common in the treatment of comminuted radial head fractures. The goal of this study was to evaluate how well the EVOLVE® modular metallic radial head implant prosthetic restores the functional range of motion and stability of the elbow. 30 patients with comminuted radial head fractures received an arthroplasty with an EVOLVE® prosthesis in our institution. 20 of those patients were available for long-term follow-up (mean > 10years). The outcomes were assessed on the basis of pain, motion, and strength. The overall outcome was scored with functional rating scores. According to the Broberg-Morrey elbow evaluation score, after a mean follow-up period of 10.2years, ten (50.0%) patients were rated as very good, four (20.0%) as good, six (30.0%) as satisfactory, and none as poor. In the long-term results the Broberg-Morrey score increased from 79 (in short-term results) to 89 points. The Disabilities of the Arm, Shoulder, and Hand (DASH) outcome measure questionnaire showed an average of 16.2 points. Initially, patients had an extension deficit of 20°, which was reduced to 5° at the latest follow-up. In our long-term results, an improvement in the function of the elbow was observed after arthroplasty using a metallic modular radial head implant. Comminuted radial head fractures with elbow instability can be treated effectively with the EVOLVE® radial head prosthesis, which restores stability in acute treatment. Our long-term results after 10.2years demonstrate good functional outcome and low major complication rate. IV.

Silicone radial head prostheses: the clinical course and treatment of failure—a case series

Silicone radial head prostheses (SRHP) have a reputation of acceptable initial function but failure in the medium to long term as a result of the disintegration of the silicone material. Damaged SRHP can result in a silicone-induced synovitis and destruction of the joint. Early removal of damaged SRHP may prevent joint destruction. Literature is scarce; there are no studies describing early symptoms associated with clinical failure of SRHP and very few studies on appropriate treatment of destructed SRHP. The aim of this study was to describe the clinical course of failing SRHP and to provide practical guidance for treatment. Fifteen consecutive cases of failed SRHP, operated between 2005 and 2020, were retrospectively reviewed, using patient logs, radiographic results, and a questionnaire. Relevant data concerning pre- and postoperative complaints, function, and surgical details were gathered. Using the questionnaire, retrospective and current patient reported outcomes including Single Assessment Numeric Evaluation (SANE) scores, pain, instability, and range of motion were analyzed. The average time between implantation of the SRHP until outpatient presentation was 16 years. The average recalled SANE score before start of complaints was 8.6 out of 10 points. In 4 patients, the onset of complaints was preceded by a trauma. Five patients had symptoms for more than a year, and 9 patients for several months. Progressive pain in the elbow and/or wrist and mechanical symptoms were early and prominent symptoms of failure. Clinical signs of synovitis were frequently present. The majority of patients had a slow but progressive onset of complaints over several months before presentation. Twelve of 15 cases of failed SRHP were surgically treated. Fragmentation of the implant, osteoarthritis, and synovitis were found in all surgically treated cases. Both surgical removal and synovectomy alone, and revision to a new radial head prosthesis resulted in good medium-term outcomes with a mean SANE score of 7.3 points at 8.4 years of follow-up. Postoperative extension lags and mild instability were frequently mentioned as a reason for reimplantation of a metallic radial head implant and removal of the radial head alone, respectively. Both patients and physicians should be aware of early symptoms of a failing SRHP. Adequate recognition, radiographic evaluation, and early intervention may favor outcomes of failing SRHP. Surgical removal is easy to perform. In selected cases, revision of the radial head prosthesis may be considered. Both of these treatment strategies resulted in satisfying outcomes.

Comparative Study between Surgical Excision of Radial Head Fracture versus Arthroplasty, a Systematic Review of Literature

Abstract Background Radial head fracture is the most frequently diagnosed fracture of the elbow in adults. The radial head is a secondary valgus stabilizer of the joint and it is involved in transmission of axial force load through the elbow during flexion. It is also a varus and external rotatory constraint. Aim of the Work to compare the functional outcome between excision of head radius and Arthroplasty in surgical management of radial head fractures (Mason types III and IV) and to assess the complications of both techniques. Patients and methods This systemic review included subjects suffered comminuted radial head fracture Mason type III or type IV treated by radial head excision or arthroplastyin the last 14 years from 2004 till 2018. Results: The database search identified 152 potentially relevant articles. Abstracts have been analyzed following inclusion and exclusion criteria and a total of 17 papers were selected for the present review. Most of retrospective studies on metal radial head prosthesis have been published in the last ten years in comparison to a lack of studies for radial head excision in the last two decades. Moreover, few articles on comparison of the two surgical techniques have been found. Because of heterogeneity in level of evidence, surgical technique, type of implants, and rehabilitation protocol, we did not perform statistical data analysis. Conclusion No clinical differences between radial head excision and arthroplasty as both methods are considerable regarding complication on long &amp; mid-term follow up and functional outcome assessed by DASH, VAS, MEPS &amp; ROM.

Evaluation of two different types of radial head prosthesis in practical use. Using either Evolve® or MoPyC® radial head prosthesis in the treatment of comminuted radial head fractures.

The aim of this retrospective study was to undertake a comparative evaluation of the Evolve® modular metallic radial head implant prosthesis and the MoPyC® pyrocarbon prosthesis in acute care. Seventyfive patients having a comminuted radial head fracture with an Evolve® prosthesis (=G1) and 11 with a MoPyC® prosthesis (=G2) were available for a follow-up. Postoperative patient outcomes were evaluated according to a standardized follow-up protocol which included the Morrey rating system. Assessment criteria were range of motion (ROM), functional scores, and rate of complications. G1 showed a mean Morrey score of 86 points. Four direct prosthesis complications were observed in this group (n=75). The average achieved Morrey score in G2 was 84 points. In this group (n=11), 2 direct prosthesis complications were diagnosed. The average range of motion did not differ greatly between both groups. Radial head replacement with either prosthesis yielded sufficient to satisfactory results in a mid-term perspective regarding the range of motion and function of the elbow joint when performed in carefully selected patients. The Evolve® Prothesis appears to show a slightly lower rate of complication by way of a similar functional outcome.

Treatment of Radial Head Fractures with a Modular Metallic Radial Head Replacement.

Radial head arthroplasty with a smooth-stemmed metallic modular implant is a reliable treatment option for patients with acute unreconstructible radial head fractures, and good clinical outcomes may be expected beyond 5 years of follow-up (Video 1). Obtain a careful history and perform a physical examination along with appropriate imaging to facilitate appropriate treatment decisions. Perform proper operating room setup and patient positioning, as they are required to gain access to all affected structures around the elbow in a safe and efficient manner. Make a midline posterior skin incision with development of a full-thickness lateral fasciocutaneous flap or use a direct lateral incision; the deep interval is determined on the basis of the integrity of the LCL. Remove and preserve all fragments of the radial head for implant sizing. Implant a prosthesis that closely replicates the dimensions of the native radial head, which is the primary goal of the procedure. Sequentially broach the canal until good cortical contact is achieved and undersize the definitive stem by 1 mm to allow implant movement within the canal and appropriate articulation with the capitellum. With the selected trial in place, assess the radial head diameter, height, and articular congruency. Ensure proper repair of the LCL as it is essential to maintaining or restoring elbow stability. Postoperative rehabilitation depends on the status of the collateral ligaments. In a review of the cases of 55 patients at a mean follow-up of 8 years after radial head arthroplasty with a smooth-stemmed modular metallic prosthesis, Marsh et al.9.

Clinical and radiographic outcome of revision surgery of radial head prostheses: midterm results in 16 patients

Little is known about revision surgery of radial head arthroplasty. The aim of this study was to report on the clinical and radiographic outcome of revision arthroplasty of the elbow with a bipolar metallic radial head prosthesis. Between 2006 and 2013, we used either a press-fit or cemented RHS bipolar radial head prosthesis for revision surgery of radial head arthroplasty in 16 patients. Patients were prospectively enrolled in the study. Differences in outcome parameters before and after revision surgery were compared. At a mean follow-up of 75 months (range, 36-116 months), none of the revised radial head prostheses needed a second revision. None of the stems showed radiographic signs of loosening. In 1 patient the head was dissociated from the prosthesis. The average flexion-extension arc was 127° (range, 105°-140°), and the average pronation-supination arc was 138° (range, 90°-160°). Stability scores improved after revision surgery, resulting in 13 stable elbows (P = .01). In 8 patients the Oxford Elbow Score was between 37 and 48 points. The percentage of patients with either good or excellent results according to the Mayo Elbow Performance Score was 63%. The mean score on the EQ-5D (EuroQol Five Dimensions) was 80 (range, 63-100), and the visual analog scale scores both for pain at rest and for pain with activity improved to 3 (range, 0-9) and 4 (range, 0-9), respectively (P < .001). All but 1 patient was satisfied with the results of the revision procedure. The clinical and radiographic outcomes of revision surgery of a radial head prostheses are favorable.

Radiocapitellar contact characteristics during prosthetic radial head subluxation

Metallic radial head prostheses are often used in the management of comminuted radial head fractures and elbow instability. We hypothesized that during radiocapitellar subluxation, the contact pressure characteristics of an anatomic radial head prosthesis will more closely mimic those of the native radial head compared with a monopolar circular or a bipolar circular radial head design. With use of 6 fresh frozen cadaver elbows, mean radiocapitellar contact pressures, contact areas, and peak pressures of the native radial head were assessed at 0, 2, 4, and 6 mm of posterior subluxation. These assessments were repeated after the native radial head was replaced with anatomic, monopolar circular and bipolar circular prostheses. The joint contact pressures increased with the native and the prosthetic radial head subluxation. The mean contact pressures for the native radial head and anatomic prosthesis increased progressively and significantly from 0 to 6 mm of subluxation (native, 0.6 ± 0.0 MPa to 1.9 ± 0.2 MPa; anatomic, 0.7 ± 0.0 MPa to 2.1 ± 0.3 MPa; P < .0001). The contact pressures with the monopolar and bipolar prostheses were significantly higher at baseline and did not change significantly further with subluxation (monopolar, 2.0 ± 0.1 MPa to 2.2 ± 0.2 MPa [P = .31]; bipolar, 1.7 ± 0.1 MPa to 1.9 ± 0.1 MPa [P = .12]). The pattern of increase in contact pressures with the anatomic prosthesis mimicked that of the native radial head. Conversely, the circular prostheses started out with higher contact pressures that stayed elevated. The articular surface design of a radial head prosthesis is an important determinant of joint contact pressures.

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

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

Long-Term Follow-up of Modular Metallic Radial Head Replacement: Commentary on an article by Jonathan P. Marsh, MD, FRCSC, et al.: "Radial Head Fractures Treated with Modular Metallic Radial Head Replacement: Outcomes at a Mean Follow-up of Eight Years".

Radial head arthroplasty is used to stabilize the joint after a complex acute radial head fracture that is not amenable for fixation or to treat sequelae of radial head fractures. Most of the currently used radial head prostheses are metallic monoblock implants that are not consistently adaptable and raise technical challenges since their implantation requires lateral elbow subluxation. Metallic modular radial head arthroplasty implants available in various head and stem sizes have been developed to improve adaptability and facilitate implantation. Bipolar radial head arthroplasty implants were developed to improve articular tracking of the prosthesis on the capitellum. Previously published studies do not allow comparisons across implants, as no comparative studies are available and indications vary with each type of implant. A meta-analysis of the published case series suggested that the outcomes are satisfactory for 81% of patients managed in the acute setting and for 73% of those managed at the stage of sequelae, after a mean follow-up of three to four years1. The outcomes do not seem to differ significantly for monoblock prostheses (50% to 94% with satisfactory outcomes), modular prostheses with a fixed radial head (61% to 97% with satisfactory outcomes), and bipolar radial head arthroplasty implants (50% to 100% with satisfactory outcomes). …

Radial Head Fractures Treated with Modular Metallic Radial Head Replacement: Outcomes at a Mean Follow-up of Eight Years.

Radial head arthroplasty is commonly used to treat acute unreconstructible radial head fractures. The purpose of this study was to report on the clinical and radiographic outcomes at a minimum follow-up of five years after radial head arthroplasty with a modular metallic implant for the treatment of acute radial head fractures. The cases of fifty-five patients with unreconstructible radial head fractures treated acutely with a smooth-stemmed modular metallic radial head implant were retrospectively reviewed. A wide variety of injuries, which ranged from isolated radial head fractures to so-called terrible triad injuries, were included. All patients returned for an interview, physical examination, and radiographic evaluation at a mean of eight years (range, five to fourteen years) postoperatively. Elbow and forearm motion, elbow strength, and grip strength were measured. Radiographs were evaluated, and validated patient-rated outcome questionnaires were completed. A longitudinal subgroup analysis was performed for thirty-three patients who were previously evaluated at two years postoperatively. At a mean of 8.2 ± 2.9 years, the mean arc of flexion (and standard deviation) of the affected elbow was 11° ± 14° to 137° ± 15°. Elbow strength and motion were significantly diminished compared with the unaffected elbow (p < 0.05). The mean Mayo Elbow Performance Index (MEPI) was 91 ± 13 points. Twenty-five patients (45%) had stem lucencies; twenty-one (38%), ulnohumeral arthritis; and twenty (36%), heterotopic ossification, including one with radioulnar synostosis. Two patients underwent secondary elbow surgery, but no patient required implant removal or revision. In the subgroup evaluated longitudinally, there was a significant improvement in MEPI scores from the two-year to the eight-year follow-up (p = 0.012), with no loss of motion or strength (p > 0.05). The mid-term outcomes of radial head arthroplasty with a smooth-stemmed modular metallic prosthesis are comparable with previously reported short-term outcomes, with no evidence of functional deterioration. Radial head arthroplasty with a smooth-stemmed metallic modular implant is a good treatment option for patients with acute unreconstructible radial head fractures, and sustained clinical outcomes may be expected beyond five years of follow-up. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Outcome of Radial Head Arthroplasty in Comminuted Radial Head Fractures: Short and Midterm Results.

Background:Comminuted radial head fractures are often associated with secondary injuries and elbow instability.Objectives:The aim of this retrospective study was to evaluate how well the modular metallic radial head implant EVOLVE® prosthesis restores functional range of motion (ROM) and stability of the elbow in acute care.Patients and Methods:Eighty-five patients with comminuted radial head fractures and associated injuries received treatment with an EVOLVE® prosthesis between May 2001 and November 2009. Seventy-five patients were available for follow-up. On average, patients were followed for 41.5 months (33.0: 4.0 - 93.0). Outcome assessment was done on the basis of pain, ROM, strength, radiographic findings, and functional rating scores such as Broberg and Morrey, the Mayo elbow performance index (MEPI), and disabilities of the arm, shoulder and hand (DASH). Our study is currently the largest analysis of clinical outcome of a modular radial head replacement in the literature.Results:Overall, there were 2 (2.7%) Mason II fractures, 21 (28%) Mason III fractures, and 52 (69.3%) Mason IV fractures. Arbeitsgemeinschaft fur osteosynthesefragen (AO) classification was also determined. Of the 85 patients in our study, 75 were available for follow-up. Follow-up averaged 41.5 months (range, 4 - 93 months). Average scores for the cohort were as follows: Morrey, 85.7 (median 90.2; range 44.4 - 100); MEPI, 83.3 (85.0; 40.0 - 100); and DASH 26.1 points (22.5; 0.0 - 75.8). Mean flexion/extension in the affected joint was 125.7°/16.5°/0° in comparison to the noninjured side 138.5°/0°/1.2°. Mean pronation/supination was 70.5°/0°/67.1° in comparison to the noninjured side 83.6°/0°/84.3°. Handgrip strength of the injured compared to the non-injured arm was 78.8%. The following complications were also documented: 58 patients had periprosthetic radioluceny shown to be neither clinically significant nor relevant according to evaluated scores; 26 patients had moderate or severe periarticular ossification, and scored substantially worse according to MEPI and Morrey. Four patients required revisional surgery due to loosening of the prosthesis and chronic pain. In addition, one patient required a neurolysis of the ulnaris nerve, one developed a neobursa, and one had extensive swelling and blistering. The time interval between injury and treatment appeared to have an effect on results. Thirty-five patients were treated within the first 5 days after accident and showed better results than the 40 patients who were treated after 5 days.Conclusions:Comminuted radial head fractures with elbow instability can be treated well with a modular radial head prosthesis, which restores stability in acute treatment. The modular radial head arthroplasty used in this study showed promising findings in short to midterm results.

Radial head replacement or repair for the terrible triad of the elbow: which procedure is better?

The terrible triad of the elbow comprises an ulnar coronoid process fracture, a radial head (RH) fracture and posterior dislocation of the elbow. It is considered severe by many clinicians because it is difficult to repair and has a poor prognosis; therefore, it deserves more attention. Thirty-nine patients with terrible triad of the elbow characterized by a Mason type-III RH fracture were randomly divided into either an RH repair group (n = 19) or an RH replacement group (n = 20). The complication rates, radiological outcomes, Mayo Elbow Performance Score and range of motion of the elbow were analysed. Follow-up demonstrated no subluxation or recurrent dislocation of the elbow. Differences in surgery duration between the groups were significant (P < 0.001). The outcomes in terms of Mayo Elbow Performance Score (P = 0.009), flexion-extension arc (P = 0.01) and pronation-supination arc (P = 0.04) were significantly better in the RH replacement group. In addition, patients in the RH replacement group displayed significantly fewer post-surgery complications than those in the RH repair group (P = 0.04). Treating Mason type-III RH fracture in a terrible triad of the elbow with a metal RH prosthesis resulted in better clinical outcomes and fewer post-surgery complications than treating a terrible triad of the elbow by repairing it with screws or plates. RH replacement might be a more effective approach to better managing a terrible triad of the elbow.

Imaging of elbow replacement arthroplasty.

Elbow replacement arthroplasty has become a standard surgical treatment for a variety of diseases of the elbow. First popularized for the treatment of late-stage rheumatoid arthritis and other debilitating forms of joint disease, the current indications have expanded to include primary treatment of elbow trauma. The most commonly used total elbow replacements are linked semiconstrained chromium-molybdenum alloy or titanium alloy prostheses with polyethylene bearing surfaces. These are inserted after resection of the ulnotrochlear joint and typically cemented in place; the radial head is often sacrificed. Modular metal components or massive osteoarticular allografts may be used when there is extensive bone deficiency. Metal radial head replacements are increasing being used for primary fracture treatment and in posttraumatic elbow reconstructive surgery. Long-term outcomes for total elbow replacement are similar to those of other joints, with 10-year survivals of ∼ 90%. Complications specific to elbow implants include infection, aseptic loosening, prosthetic failure, and periprosthetic fracture.

Influence of radial head prosthetic design on radiocapitellar joint contact mechanics

Our aim was to test whether anatomically designed metallic radial head implants could better reproduce native radiocapitellar contact pressure and areas than nonanatomic implants. The distal humerus and proximal radius from 6 cadaveric upper extremities were serially tested in supination with 100 N of compression force at 4 angles of flexion (0°, 30°, 60°, and 90°). By use of a thin flexible pressure transducer, contact pressures and areas were measured for the native radial head, an anatomic implant, a nonanatomic circular monopolar implant, and a bipolar nonanatomic implant. The data (mean contact pressure and mean contact area) were modeled using a 2-factor repeated-measures analysis of variance with P ≤ .05 considered to be significant. The mean contact areas for the prosthetic radial heads were significantly less than those seen with the intact radial heads at every angle tested (P < .01). The mean contact pressures increased significantly with all prosthetic radial head types as compared with the native head. The mean contact pressures increased by 29% with the anatomic prosthesis, 230% with the monopolar prosthesis, and 220% with the bipolar prosthesis. Peak pressures of more than 5 MPa were more commonly observed with both the monopolar and bipolar prostheses than with the anatomic or native radial heads. The geometry of radial head implants strongly influences their contact characteristics. In a direct radius-to-capitellum axial loading experiment, an anatomically designed radial head prosthesis had lower and more evenly distributed contact pressures than the nonanatomic implants that were tested.

The effect of excision of the radial head and metallic radial head replacement on the tension in the interosseous membrane

We measured the tension in the interosseous membrane in six cadaveric forearms using an in vitro forearm testing system with the native radial head, after excision of the radial head and after metallic radial head replacement. The tension almost doubled after excision of the radial head during simulated rotation of the forearm (p = 0.007). There was no significant difference in tension in the interosseous membrane between the native and radial head replacement states (p = 0.09). Maximal tension occurred in neutral rotation with both the native and the replaced radial head, but in pronation if the radial head was excised. Under an increasing axial load and with the forearm in a fixed position, the rate of increase in tension in the interosseous membrane was greater when the radial head was excised than for the native radial head or replacement states (p = 0.02). As there was no difference in tension between the native and radial head replacement states, a radial head replacement should provide a normal healing environment for the interosseous membrane after injury or following its reconstruction. Load sharing between the radius and ulna becomes normal after radial head Replacement. As excision of the radial head significantly increased the tension in the interosseous membrane it may potentially lead to its attritional failure over time.

Can Ulnar Variance Be Used to Detect Overstuffing After Radial Head Arthroplasty?

Overstuffing of the radiocapitellar joint during metallic radial head arthroplasty has been reported to cause loss of elbow flexion, capitellar erosion, and early-onset osteoarthritis. Although this is known, there is no agreed-on measurement approach to determine whether overstuffing has occurred. We therefore hypothesized that overlengthening the radial head during radial head arthroplasty changes the ulnar variance in the wrist. Seven cadaveric radii were implanted with radial head prostheses of increasing thickness. Each specimen was implanted successively with increasingly thick radial head prostheses measuring 2, 4, and 6 mm thicker than the native radial head, and radiographs were taken after implantation of each prosthesis. The ulnar variance with each prosthesis was measured using the method of perpendiculars. The ulnar variance of the native and 2-mm (p = 0.04), 4-mm (p = 0.008), and 6-mm (p = 0.008) overly thick radial head prosthesis-implanted states decreased significantly with each incremental increase in prosthetic head thickness. Implantation of thicker radial head prostheses decreased the ulnar variance. Our results indicate ulnar variance could be used to detect overstuffing of radial head prostheses. The simplicity and reliability of ulnar variance make it a potentially useful indicator of overlengthening after radial head arthroplasty.

Clinical and radiographic comparisons of two different radial head implant designs

There is little comparative data to guide implant choice for radial head replacements. The purpose of this study was to evaluate the clinical and radiographic results between patients who received a smooth-stemmed bipolar radial head implant and patients who received an in-growth monopolar prosthesis. Twenty-seven patients requiring a metallic radial head implant in the management of acute or chronic elbow trauma were evaluated. Fourteen patients received a smooth-stemmed bipolar prosthesis and 13 patients received a press-fit monopolar prosthesis. Patients returned for follow-up at an average of 33 months (range, 18-57). Outcome assessments included joint motion, elbow stability, grip strength, pain, the Mayo Elbow Performance Index, and the Disability of Arm, Shoulder and Hand questionnaire. Radiographs were reviewed for joint congruence, ectopic bone, periprosthetic osteolysis, degenerative arthritis, and capitellar wear, and selected patients were tested for inflammatory markers and metal ion levels. The differences between patient groups for elbow flexion and forearm pronation averaged 10° or less. There were no other pertinent differences between groups for standardized patient and examiner-determined outcomes. There was a trend for ectopic bone to develop more commonly around the smooth-stemmed implants, while periprosthetic osteolysis was more pronounced in cases with the press-fit design. Inflammatory markers were normal, and metal ion levels did not exceed values reported for a well-functioning hip arthroplasty. Outcomes at short- to mid-term follow-up were similar with either implant design. Loosening of a press-fit prosthesis may lead to extensive osteolysis, but of undetermined clinical consequence.

Radial Head Arthroplasty: A Radiologic Outcome Study

The purpose of this study is to provide a radiographic outcome assessment of radial head arthroplasty in correlation with clinical outcomes and to determine whether there is an association between certain patient factors and clinical and radiographic outcomes. A 10-year retrospective review was performed to identify patients with metal radial head arthroplasty. At least two follow-up radiographs were reviewed for each patient and were correlated with clinical information. Statistical analysis included calculation of complication rates, phi coefficient for variable association with complications, and Kaplan-Meier survival. A total of 258 radial head implants in 244 patients were reviewed. The mean patient age was 46 years, with mean follow-up time of 12.8 months. Two hundred nineteen (84.9%) implants were unipolar in design, whereas 39 implants were bipolar. The most common indication for arthroplasty was trauma (94% acute and 2% failed internal fixation). Radiographic abnormalities included nonbridging heterotopic ossification (38.0%), secondary radiocapitellar joint osteoarthritis (27.9%), loosening (19.8%), bridging heterotopic ossification (8.9%), fracture (2.3%), and hardware dislocation (2.7%). Overall, there were 62 second surgeries for either revision or removal. Reasons for second surgery included heterotopic ossification (53.2%), synovectomy or capsulectomy (43.5%), and infection (3.2%). There was a statistically significant association between radiographic complications and the presence of patient symptoms (p < 0.05). There was no association between radiographic or clinical complications with age, sex, side, or type of arthroplasty (R < 0.001). There is a positive association between radiographic findings and patient symptoms for postoperative complications after radial head arthroplasty. By 9 months, 50% of implants showed radiographic complications.

요골두 치환술의 임상적 적용

Purpose: Installing a radial head prosthesis has developed into a reliable procedure to replace the native radial head for treating unreconstructible radial head fracture when this is associated with an unstable elbow or forearm. A variety of implants have been developed and these are now commercially available. This article reviews the literature related to the indications, the available implants and the surgical techniques of radial head replacement arthroplasty. Materials and Methods: The main indication for a metallic radial head prosthesis is a comminuted fracture that is not amenable to reconstruction, and particularly if it is associated with complex elbow injuries. Excision of the radial head should be avoided in the presence of combined injured ligaments or interosseous membrane injury. Three different implants are available in Korea, including the bipolar, press fit monopolar and loose fit monopolar radial head prostheses. A primary technical goal of radial head arthroplasty is the insertion of an implant that closely replicates the native radial head. The major pitfall when using a metallic radial head prosthesis is the insertion of a longer implant, which results in overstuffing of the radiocapitellar joint. Results and Conclusion: Satisfactory clinical results can be anticipated when a radial head prosthesis is used for the correct indications and when a systemic approach is undertaken to ensure proper sizing. For the future studies, we need data regarding the long term outcomes and comparison of the various types of prostheses.