Kinematics and stability of the fractured and implant-reconstructed radial head

Missed Monteggia Injuries in Children and Adolescents: A Treatment Algorithm

Monteggia injuries are rare childhood injuries. In 25-50% of cases, however, they continue to be overlooked, leading to a chronic Monteggia injury. Initially, the chronic Monteggia injury is only characterized by a moderate motion deficit, which is often masked by compensatory movements. Later, however, there is a progressive valgus deformity, neuropathy of the ulnar nerve and a progressive deformity of the radial head ("mushroom deformity") with ultimately painful radiocapitellar arthrosis. In the early stages, when the radial head is not yet deformed and there is no osteoarthritis in the humeroradial joint, these injuries can be treated with reconstruction procedures. This can be achieved either by an osteotomy of the proximal ulna with or without gradual lengthening. If there is already a severe deformity of the radial head and painful osteoarthritis, only rescue procedures such as functional radial head resection or radial head resection with or without hemi-interposition arthroplasty can be used to improve mobility and, above all, to eliminate pain. In this review article, we provide an overview of the current treatment options of chronic Monteggia injury in children and adolescents and present a structured treatment algorithm depending on the chronicity and dysplastic changes.

Preoperative and operative risk factors for failed lateral collateral ligament reconstruction

Repair or reconstruction of the lateral collateral ligament (LCL) using autograft or allograft is a well-accepted treatment of posterolateral rotatory instability. The prevalence and causes for failure of LCL reconstruction are not well documented in the literature. Any approach to the assessment and management of failed LCL reconstruction must begin with understanding the risk factors for failure in the first place. Such understanding would likely make many failures preventable as well. In our experience, there are a number of identifiable preoperative risk factors concerning bony and/or soft tissue constraints for failure of LCL reconstruction. There are also operative factors such as tunnel and graft placement as well as excessive lateral condyle stripping that play a role in risk of failure. This report is an attempt to provide a systematic approach to identifying and managing the preoperative and operative risk factors. Further studies are warranted to determine the indications for, and success rates of surgical intervention in managing these risk factors.

Trans-olecranon fracture posterior dislocation: a novel type of elbow injury

BACKGROUND

Based on our experiences, we found that a kind of elbow injury is characterized by an olecranon fracture accompanied by elbow joint posterior dislocation with the proximal radioulnar joint intact. The aim of this study was to better define this kind of severe elbow instability, which has not been previously reported.

METHODS

We retrospectively analyzed all patients with olecranon fractures who were treated at our institution from January 2013 to April 2021. Data on these patient demographics, injury characteristics, preoperative and postoperative imaging, surgical management, and outcomes were recorded and analyzed. We also made the inclusion criteria and exclusion criteria.

RESULTS

A total of 309 patients were diagnosed olecranon fractures in our institution, and ten patients met the inclusion criteria, 9 males and 1 female, with an average age of 40.6 ± 12.7 years (26-68 years). Eight patients (80%) were comminuted, and two were oblique olecranon fracture. Nine patients (90%) suffered coronoid process fractures, eight fractures were type III, and one was type II. Eight patients (80%) suffered radial head fractures, seven fractures were type II, and one was type III. All patients suffered lateral collateral ligament complex injury. All patients underwent surgical management and were followed up on average for 15.8 ± 3.2 months (12-20 months). The motion of the elbow and functional outcome were evaluated with several methods. The mean arc of the elbow movement was 131.6° ± 6.0° (124°-140°), and the mean arc of the forearm rotation was 158.5° ± 17.8° (128°-180°). Nine patients' functional results according to the Mayo Elbow Performance Score (MEPS) were excellent with a mean score of 96.5 ± 5.3 points (85-100 points), and another was good. The mean score according to the Broberg and Morrey functional rating index was 98.8 ± 2.5 points (92-100 points), nine patients were excellent, and another was good. The mean Disabilities of the Arm, Shoulder, and Hand (DASH) score was 0.75 ± 1.2 points (0-3.3 points).

CONCLUSIONS

Trans-olecranon fracture posterior dislocation is a rare injury and has unique characteristics, and it is a kind of complex elbow instability involving the coronoid process and radial head fractures. After bony structure is restored, the repairment of lateral collateral ligament complex is also important to the stability of the elbow joint. Correct understanding of this kind of injury and reasonable treatment plan can achieve good function.

Autologous replacement of the head of the radius-proximal fibula versus second metatarsal base: an anatomic feasibility study

INTRODUCTION

This study investigated the anatomic feasibility of a new surgical therapy option for radial head arthrosis using an autologous vascularized bone graft of the second metatarsal and proximal fibula to recreate the proximal radiohumeral joint.

MATERIALS AND METHODS

Upper and lower extremities of eleven body donors were evaluated using CT prior to anatomic dissection. Several distinct anatomic parameters were measured on the ipsi- and contralateral radial and fibular head and the second metatarsal base: bone diameter, articular surface diameter, head height, metaphyseal (neck) diameter, articular surface radius, total articular surface area, and angulation of the articular surfaces (facet). Each dissection phase was photographed in a standardized fashion and all measurements were repeated by direct caliper-measurements.

RESULTS

When comparing the proximal radius and fibula to search for anatomic similarities, similar values were found in the maximum articular surface diameter and minimum and maximum measures of the neck diameter. Comparing the proximal radius and the second metatarsal, statistically similar values were found in the maximum neck diameter performing direct measurements and CT evaluation, the maximum head diameter in CT evaluation and the articular facet angulation.

CONCLUSIONS

Neither the proximal fibula nor the base of the second metatarsal are ideal bone grafts for replacement of the head of the radius. The base of the second metatarsal might be a bit more suitable as a potential donor since the angulation of the proximal articular facet is similar to that of the radius.

LEVEL OF EVIDENCE

Level IV, anatomic study.

Surgical Management of Complex Adult Monteggia Fractures

Monteggia fractures classically involve a proximal ulna fracture with an associated radial head dislocation. The presence of radial head/neck fracture and comminution of the proximal ulna with coronoid involvement elevates the complexity of surgical reconstruction considerably. The Jupiter classification captures this injury pattern as a subgroup of Bado posterior Monteggia lesions. Access to the critical coronoid fragment can be problematic from the posterior approach and may result in tenuous reduction and fixation, directly affecting the functional outcome. Multiple operative techniques have been described to address the broad spectrum of injuries seen in Monteggia fractures. This article will cover commonly used fixation techniques for Monteggia fractures with a comprehensive literature review, including technical tips, outcomes, and complications.

Radiographic evaluation of partial articular radial head fractures: assessment of reliability

Background

Historically, treatment of partial articular radial head fractures has hinged on radiographic assessment and application of the Mason classification. The inter- and intra-rater reliability of radiographic assessment and classification of radial head fractures may be lower than previously reported. We hypothesized that radiographic assessment leads to an underestimation of the number of fragments, percentage of articular surface involved, and displacement in millimeters.

Methods

We performed a retrospective review of all Mason II radial head fractures treated at our institution. Four independent observers performed radiographic assessment of the cohort. An independent observer performed these measurements on high-resolution computed tomography (CT) imaging, the reference standard. Radiographic assessments were then correlated with the CT findings using Pearson's correlation coefficient and Kappa statistic, where indicated.

Results

Fifty-nine Mason II radial head fractures were reviewed. These results were not impressive, with all comparisons showing a Kappa statistic less than 0.5 (ie, weak agreement). Intra-rater reliability was similar: displacement (measured by Pearson's correlation coefficient) was 0.58, percent articular involvement was 0.74, and the number of fragments (measured by the Kappa statistic) was 0.28. Fracture displacement was generally underestimated on radiographic measurements when compared to CT scan. Nearly half (45%) of all cases demonstrated inaccurate fragment number assessment when compared to the reference standard.

Conclusion

Radiographs show poor inter- and intra-observer reliability for determining radial head fracture morphology. Assessment of the number of fragments was particularly inaccurate. High-resolution CT should be considered for patients with Mason II radial head fractures, especially in cases of poorly visualized fracture characteristics or borderline amounts of displacement, in an effort to appropriately indicate patients for the variety of treatment options available today.

Radial head excision and Achilles allograft interposition arthroplasty for the treatment of chronic pediatric radiocapitellar pathologies: A report of four cases

BACKGROUND

Severe radiocapitellar pathologies represent a unique problem in the pediatric population, as radial head excision can lead to substantial long-term complications. We present a case series of four pediatric patients treated by a novel technique-radial head excision followed by Achilles allograft interposition arthroplasty.

METHODS

Four children (ages 12-15 years) are described. Their clinical and radiographic outcomes were assessed by a visual analog scale, the Mayo Elbow Performance Score, the Disabilities of the Arm, Shoulder and Hand questionnaire, grip strength, and range of motion.

RESULTS

At a mean follow-up of two years, the average flexion-extension arc of motion improved from 107° to 131°, and the rotation arc improved from 100° to 154°. The average visual analog scale, Mayo Elbow Performance Score, and Disabilities of the Arm, Shoulder and Hand scores were 2, 92.5, and 11.5, respectively. Two patients required subsequent additional procedures-manipulation under anesthesia and ulnar shortening osteotomy. Proximal migration of the radius was observed in three out of the four patients.

DISCUSSION

Combined radial head excision and Achilles allograft interposition arthroplasty represents a viable option for the treatment of chronic pediatric radiocapitellar pathologies, with good results in terms of clinical and functional outcomes as well as patient satisfaction in the short-medium term.

Precision of computed tomography and cartilage-reproducing image reconstruction method in generating digital model for potential use in 3D printing of patient-specific radial head prosthesis: a human cadaver study

Background

A prosthetic replacement is a standard treatment for an irreparable radial head fracture; however, the surface mismatch of the commercially available designs is concerned for the long-term cartilage wear. The patient-specific implant created from 3D printing technology could be favorable in replicating the normal anatomy and possibly reduce such sequela. Our study aimed to assess the precision of the computed tomography (CT) and cartilage-reproducing image reconstruction method (CIRM) in generating digital models for potentially use in manufacturing the patient-specific prosthesis from 3D printing.

Methods

Eight intact  elbows (3 right and 5 left) from 7 formalin-embalmed cadavers (4 males and 3 females) with mean age of 83 years (range, 79–94 years) were used for this study. Computerized 3D models were generated from CT, and CIRM. The cartilage-reproducing image reconstruction method has compensated the cartilage profile based on the distance between the subchondral surfaces of the radial head and surrounding bones in CT images. The models of actual radial head geometry used as the gold standard was generated from CT arthrography (CTA). All models of each specimen were matched by registering the surface area of radial neck along with the tuberosity. The difference of head diameter, head thickness, and articular disc depth among three models was evaluated and analyzed by Friedman ANOVA and multiple comparison test using Bonferroni method for statistical correction. A p-value of less than 0.01 was considered statistically  significant. The difference of overall 3D geometry was measured with the root mean square of adjacent point pairs.

Results

The analysis displayed the difference of diameter, thickness, and disc depth across the models (p< 0.01). Pairwise comparisons revealed statistically significant difference of all parameters between CTA models and CT models (p< 0.01) whereas no difference was found between CTA models and CIRM models. The mean difference of overall 3D geometry between CTA models and CT models was 0.51±0.24 mm, and between CTA models and CIRM models was 0.24±0.10 mm.

Conclusions

CIRM demonstrated encouraging results in reestablish the normal anatomy and could be potentially used in production process of 3D printed patient-specific radial head prosthesis.

Indications and outcomes of radial head excision: A systematic review

BACKGROUND

Radial head excision has historically been a common surgical procedure for the operative management of radial head fractures and post-traumatic conditions. With recent advances in other surgical techniques, controversy exists regarding its indications. This review evaluates the indications and outcomes of radial head excision in traumatic and non-traumatic elbow pathology.

METHODS

Multiple databases were searched for studies involving radial head excision. Screening and data abstraction were conducted in duplicate. Only studies reporting outcomes for radial head excision were included.

RESULTS

Twenty-seven studies with 774 radial head excision patients were included. The most common indications involved acute excision of comminuted radial head fractures (n = 347) and rheumatoid arthritis (n = 201). Post-operative functional scores after acute excision were reported to be good to excellent. In the chronic setting of rheumatoid disease, radial head excision resulted in improved range of motion, although pain was not effectively relieved.

DISCUSSION

Outcomes of radial head excision for acute fracture are good to excellent; however, it should not be performed when concurrent or ligamentous injuries are present. Although some studies compared excision to open reduction and internal fixation or replacement, more data are needed to make proper conclusions. The strength of these conclusions is limited by the quality of included literature.

Indirect 3D printing technology for the fabrication of customised β-TCP/chitosan scaffold with the shape of rabbit radial head-an in vitro study

Background

With the development of indirect three-dimensional (3D) printing technology, it is possible to customise individual scaffolds to be used in bone transplantation and regeneration. In addition, materials previously limited to the 3D printing (3DP) process due to their own characteristics can also be used well in indirect 3DP. In this study, customised β-TCP/chitosan scaffolds with the shape of rabbit radial head were produced by indirect 3D printing technology.

Methods

Swelling ability, porosity, mechanical characterisation, and degradation rate analysis were performed, and in vitro studies were also implemented to evaluate the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (MSCs) on the scaffolds. CCK8 cell proliferation assay kit and alkaline phosphatase (ALP) staining solution were used to study cell proliferation and early ALP content at the scaffold surface. Moreover, the osteogenic differentiation of MSCs on scaffolds was also evaluated through the scanning electron microscopy analysis.

Results

β-TCP/chitosan scaffold has good performance and degradation rate, and in vitro cell experiments also confirm that the scaffold has adequate cytocompatibility and bioactivity.

Conclusion

This study provides a promising new strategy for the design of customised scaffolds for the repair of complex damaged tissues.

Reasons for surgical revision after conservatively treated radial head fractures-retrospective study of 70 patients

Background

An inadequate clinical outcome after conservatively treated radial head fractures is not uncommon. We analyzed the subjective limitations, objective complaints, and surgical procedures for radial head fractures initially treated conservatively.

Patients and method

Between 2007 and 2016, 70 patients (42 men, 28 women) who suffered from fracture sequelae after conservatively treated radial head fractures were examined. Demographic (age, 41.8 years, range, 16–75 years) and clinical data (pain, range of motion, instability) were retrospectively evaluated.

Results

The average time to surgery after trauma was 50 months (range, 5–360 months). In 38 cases, radial head fractures were initially treated with immobilization for 3.4 weeks (range, 1–8 weeks). Physiotherapeutic treatment was performed in 39 cases. In only half of the cases was retrospective Mason classification possible: 20 type I, 8 type II, 5 type III, and 2 type IV. Of the 70 patients, 53 had posttraumatic elbow stiffness; 34 had isolated lateral and four patients isolated medial ligament instability. There were eight cases with a combination of lateral and medial ligament instability and 27 cases of elbow stiffness combined with instability. An average of 1.2 (range, 1–4) surgical procedures per patient were performed. In all, 64 patients underwent elbow arthroscopy with arthrolysis and additional treatment depending on other injuries. The range of motion improved on average from preoperative flexion/extension of 131–15–0° to postoperative flexion/extension of 135–5–0° (gain in flexion: 4.2° and extension: 10.6°).

Conclusion

Conservative treatment of radial head fractures does not always yield good results. Reasons for a poor outcome include chronic instability, cartilage damage, stiffness, or a combination thereof. Improved outcomes can be achieved via arthroscopic arthrolysis.

Long-term outcomes of modular metal prosthesis replacement in patients with irreparable radial head fractures

BACKGROUND

The purposes of this study were to investigate the long-term outcomes of radial head replacement and to analyze the relationship between functional outcomes and periprosthetic radiolucency.

METHODS

We retrospectively reviewed 32 patients who underwent unilateral radial head replacement between 2004 and 2011. Data on patient characteristics including age, gender, injury complexity, associated trauma, injury chronicity, and number of surgeries were collected and analyzed. Of these patients, 14 had terrible triad injury, 14 valgus-type injuries, 3 Monteggia fracture, and 1 concomitant distal humerus fracture. Clinical survey was performed at 7 to 15 years after replacement surgery. The Mayo Elbow Performance Score (MEPS) and shortened Disabilities of the Arm, Shoulder, and Hand (quickDASH) score were used for functional evaluation. Residual elbow or forearm pain was evaluated using visual analog scale (VAS). Radiographs were reviewed by orthopedic and radiologic specialists, and periprosthetic radiolucency was measured based on the diameter of radial head prosthesis.

RESULTS

The 32 patients returned for follow-up at an average of 8.94 years. None underwent prosthesis revision or removal. MEPS averaged 83.4; good or excellent results were achieved in 26 patients. QuickDASH scores averaged 11.7. Significantly better MEPS (p = 0.023) and quickDASH scores (p = 0.026) were noted when replacement surgery served as the primary surgery instead of late salvage. VAS scores averaged 1.25, with residual pain noted in 24 elbows (75%). Periprosthetic radiolucency was noted in 21 patients (66%) with a mean thickness of 3.53 mm. The difference in functional outcomes was not significant between patients with and without radiolucency, with p values of 0.127 for MEPS and 0.135 for quickDASH scores. Spearman correlation analysis showed low correlation between the measured width of radiolucency and VAS scores (r = 0.143).

CONCLUSION

Sustained, encouraging clinical outcomes were reported in the present study. Although periprosthetic radiolucency did not correlate with functional or pain scores, surgical optimization and meticulous survey were warranted.

Results after radial head arthroplasty in unstable fractures

BACKGROUND

Whereas most radial head fractures are stable injuries, they sometimes occur as part of complex injury patterns with associated elbow instability. Radial head arthroplasty has been favored in patients with unreconstructable radial head fractures and unstable elbow injuries. The purpose of this study was to review radiographic outcomes, functional outcomes, and complications after radial head arthroplasty for radial head fracture in unstable elbow injuries.

METHODS

This study was a retrospective review of radial head fractures treated with radial head arthroplasty by a single surgeon during a 15-year period. Demographics of the patients, injury details, operative reports, radiographic and clinical outcomes, and any complications were recorded. Patients were divided into stable and unstable elbow injury groups.

RESULTS

A total of 68 patients were included. There were 50 unstable fractures that were compared with 18 stable fractures. Patients with unstable radial head fractures with associated elbow dislocation achieved mean flexion and mean forearm rotational arc of motion similar to that of patients with stable radial head fractures. However, supination loss was greater in the unstable group than in the stable fracture group, with a mean difference of 10°. Radiographic outcomes and complication rates did not differ between injury groups. There was no observed decrease in implant longevity in patients with unstable elbow injuries.

CONCLUSIONS

Radial head arthroplasty is an effective option for treatment of unstable elbow injuries, with recovery of functional elbow range of motion and no difference in complication rate or implant survivorship compared with those patients with stable injuries.

Treatment of Modified Mason Type III or IV Radial Head Fracture: Open Reduction and Internal Fixation versus Arthroplasty

BACKGROUND

The treatment of modified Mason Type III or IV fractures is controversial. Many authors report open reduction and internal fixation (ORIF) with reconstruction of the radial head, but others advocate radial head arthroplasty (RHA). This study compares the clinical and radiological outcomes of ORIF and RHA in modified Mason Type III or IV radial head fracture and evaluates correlations between prognostic factors and postoperative clinical outcomes.

MATERIALS AND METHODS

42 patients with modified Mason Type III or IV radial head fractures who were surgically treated between January 2010 and January 2014 were retrospectively analyzed (20 patients with RHA and 22 patients with ORIF group were selected). Clinically, the patient rated elbow evaluation (PREE), the disabilities of the arm, shoulder and hand (DASH), and the range of motion (ROM) were measured. Radiologically, plain radiographs and computed tomography scans were taken.

RESULTS

The mean PREE scores were 13.9 for the RHA group and 13.0 for the ORIF group, and mean DASH scores were 9.5 and 10.7, respectively. The differences were not statistically significant. When comparing ROM, the patients in the RHA group showed greater movement at all measured angles. In multiple regression analysis, age was the only variable significantly associated with both PREE and DASH.

CONCLUSION

Overall, there were no significant differences in clinical outcomes of modified Mason Type III or IV radial head fractures treated with ORIF or RHA. However, a subgroup of younger patients had better clinical outcomes with ORIF treatment. Therefore, ORIF should be the First line of treatment, particularly if the reduction is possible.

Effect of Concomitant Elbow Injuries on the Outcomes of Radial Head Arthroplasty: A Cohort Comparison

OBJECTIVES

To compare physical impairments and patient-reported outcomes in patients after simple and complex elbow injuries who were treated with radial head arthroplasty.

DESIGN

Prospective.

SETTING

Quaternary upper extremity referral hospital.

PATIENTS/PARTICIPANTS

148 patients with isolated elbow trauma and no previous injury to the elbow were prospectively enrolled after radial head arthroplasty for an acute unreconstructable fracture. Injury patterns were classified as simple or complex based on the presence or absence of associated elbow fractures and/or dislocation.

INTERVENTION

Radial head arthroplasty.

MAIN OUTCOME MEASUREMENTS

Patient-Rated Elbow Evaluation (PREE), Disability of the Arm, Shoulder, and Hand, range of motion (ROM), and Biodex measurements.

RESULTS

At a minimum 1-year follow-up PREE and Disability of the Arm, Shoulder, and Hand, and ROM and strength values were similar. Forty-four patients evaluated at a mean of 7 years demonstrated no effect of injury pattern on clinical outcomes at any time point. Continued statistical improvements in PREE, supination ROM, and flexion ROM at medium term compared with earlier follow-up were observed. Eight patients required secondary surgery, 2 in the simple injury group and 6 complex injury patients.

CONCLUSIONS

Concomitant elbow injuries do not affect the longer term outcomes of patients with unreconstructable radial head fractures requiring radial head arthroplasty. Patient outcomes continued to improve beyond 2 years of follow-up.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Radial head prosthesis: results overview

Background/purpose

Radial head replacement is frequently used in treatment of radial head fractures or sequela. Impossibility to restore a correct anatomy, acute elbow traumatic instability and failure of osteosynthesis hardware are the most common indications. The authors describe their case studies and results on the implantation of various radial head prostheses.

Materials

Between June 2005 and June 2016, 28 radial head prostheses were implanted in the same number of patients with an average follow-up of 49 months (6–104). Indications for implantation were: Mason type III and IV radial head fractures and post-traumatic arthritis due to failure of previous treatments. Monopolar prostheses were used and were press-fit implanted via Kaplan’s lateral access and Kocher’s anconeus approach to the humeroradial joint. At the follow-up, assessments were made of the pain, according to the visual analogic scale, range of motion (ROM), stability and functionality according to the Mayo Elbow Performance Score, presence of osteolysis and mobilization during radiography tests, personal satisfaction of the patients, Disabilities of the Arm, Shoulder and Hand and Patient-Rated Wrist Evaluation outcomes measurements.

Results

At the follow-up, we recorded an average level of pain of 1.8 in patients under acute treatments for radial head fractures and a marked reduction in the remaining cases from 6.7 to 2.1. ROM was found on average to be 107° of flexion–extension and 159° of pronosupination. Personal satisfaction was good–excellent in 23 cases. There was no case of infection; removal of the implant was necessary in three cases due to mobilization of the stem and oversized implants. In six cases, bone resorption was seen at the level of the prosthetic collar and it was in all cases asymptomatic.

Conclusions

The results of this study suggest that the use of prostheses, if well positioned, is a valid solution in the treatment of secondary arthritis and fractures of the radial head with poor prognosis, with good results in the reduction of pain, recovery of movement and improved quality of life.

[Locking plate osteosynthesis of the radial head fractures : clinical and radiological results]

BACKGROUND

Therapy of radial head fractures is still controversially discussed. Especially comminuted fractures are at risk of complications such as radial head necrosis, nonunion and secondary loss of reduction after open reduction and internal fixation. The aim of this study was to evaluate clinical and radiographic results of ORIF (open reduction internal fixation) of radial head fractures using a new radial head-specific locking plate system.

PATIENTS AND METHODS

A total of 21 patients (13 men and 8 women) were treated with locking plate osteosynthesis of radial head fractures. Mean age was 50 years (range 29-67 years). According to the Mason classification, 15 were type III and 6 type IV. Mean time between trauma and surgery was 5.6 days (range 0-23 days). These patients were reexamined using the Mayo Elbow Performance Score and x-rays in two planes.

RESULTS

In all, 21 patients were reexamined with a mean follow-up of 12.1 months (range 5-23 months). The mean Mayo Elbow Performance Score was 87.1. Excellent results were obtained in 12 patients, good results in 6 patients, and fair results in 3 patients. Mean extension deficit was 12.1°, mean flexion 135.2°, mean pronation 70.9°, and mean supination 63.6°. All fractures healed uneventfully. There was no complete radial head necrosis but one partial. Four cases of heterotopic ossification were detected: Hastings classification I (n = 2), IIb (n = 1), IIIb (n = 1).

CONCLUSION

ORIF of radial head fractures using locking plates can lead to good and excellent results. Modern implants may allow for reconstruction of comminuted fractures avoiding arthroplasty in these young patients.

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.

Resection arthroplasty after failure of a radial head prosthesis: a case report

Radial head represents a secondary elbow stabilizer for varus-valgus and postero-lateral stress. In complex fractures, that cannot be synthesized, the presence of associated ligament injuries makes radial head replacement necessary to restore elbow stability. This study evaluates how the elbow responds to a prosthetic removal after a complex injury repair.

Fractures of the Radial Head

Radial head fractures are the most common fractures around the elbow. Because they are often accompanied by ligamentous injuries, we recommend considering them to be osteoligamentous injuries rather than simple fractures, even in undisplaced or minimally displaced fractures. Surgeons should always suspect and actively exclude concomitant ligament tears. The incidence of these associated injuries increases with greater severity of the radial head fracture. However, the standard Mason classification system does not adequately address this problem, and all attempts to establish a new classification system that provides concise treatment algorithms have failed. This article discusses the current treatment options and the current controversies in nonsurgical therapy, open reduction and internal fixation (ORIF) and radial head replacement.

Adult Monteggia and Olecranon Fracture Dislocations of the Elbow

Monteggia fractures and olecranon fracture dislocations represent complex injuries with distinct patterns of bony and soft tissue involvement. Fractures of the proximal ulna and olecranon process may lead to disruption of the proximal radioulnar joint and/or ulnohumeral joint. The keys to treatment are recognition of the pattern of injury and formation of an algorithmic surgical plan to address all components of the injury process. Complications are common and may be related to the injury spectrum itself and/or inadequate fracture alignment or fixation.

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.

Open reduction and internal fixation versus radial head arthroplasty in the treatment of adult closed comminuted radial head fractures (modified Mason type III and IV)

BACKGROUND

The purpose of our study was to compare the outcome of radial head fractures (modified Mason type III and IV) treated by open reduction and internal fixation (ORIF) versus radial head arthroplasty (RHA).

PATIENTS AND METHODS

A retrospective review of 36 patients with closed comminuted radial head fractures treated either by ORIF or RHA with an average of 15-months' follow-up was undertaken. The primary outcome was the QuickDASH, the shortened version of the Dissabilities of the Arm, Shouler and Hand score. Other outcomes included regain of functional range of motion (ROM) of the elbow and duration of surgery. Surgical complications were noted.

RESULTS

Thirty-six patients with a mean age of 36 years were evaluated. Nineteen patients underwent ORIF and 17 RHA. The two treatment groups were comparable with regards to gender, side of injury, Mason type and mechanism of injury. Patients who underwent RHA were slightly older (p < 0.001). At follow-up, the QuickDASH score was similar between groups (p = 0.58). Regain of functional ROM of the elbow (p = 0.13) and complication rate (p = 0.57) were similar.

CONCLUSION

The treatment of closed comminuted radial head fracture (modified Mason type III and IV) with ORIF and RHA demonstrates similar findings despite less surgical time for performing RHA.

Unique model evokes the supination/pronation deficits found after Mason II fractures

A rapid prototyping model of Mason II fracture was used to investigate baseline recommendations for surgical intervention founded on kinematic forearm rotational blockage. Exact replicas of the radial heads in nine cadaveric specimens were produced and specimens were tested in a physiologic elbow simulator. After testing supination/pronation, the rotations were repeated with native replicas and with replicas modeling 3 mm depressed Mason II fractures with and without a gap of 1 mm between the body and fragment. The fragments were located circumferentially around the radial head at 10, 2 and 6 o'clock positions. There was no statistical difference between the range of motion of the native case and the native replica without fracture. After inclusion of the fracture, seven of the nine specimens showed rotational blockages. A two-way ANOVA found no statistical difference due to type of Mason II fracture (p > 0.87) or fracture location (p > 0.27). A χ-square analysis showed that presence of a kinematic deficit with a fractured radial head was significant (p < 0.03). The results support continued surgical intervention for a 3 mm depressed fracture and also establish the use of the rapid prototype as a model for kinematic investigation of fractures in a cadaveric model when ligamentous attachments are preserved.

Outcomes of bipolar radial head prosthesis to treat complex radial head fractures in 22 patients with a mean follow-up of 50 months

BACKGROUND

Radial head replacement is indicated to treat complex proximal radial fractures that are not amenable to internal fixation.

HYPOTHESIS

Implantation of a bipolar radial head prosthesis after radial head excision ensures stability of the elbow and forearm, thereby promoting ligament healing and restoring elbow function.

MATERIAL AND METHODS

Twenty-two patients managed with implantation of a bipolar radial head prosthesis (Guepar(®)) were evaluated after a mean follow-up of 50 months. The procedure was performed in the acute setting in 16 patients, including 13 with associated injuries; and at the stage of sequelae in 6 patients.

RESULTS

Prosthesis removal was required in 4 patients. Of the remaining 18 patients, 14 (77%) had satisfactory Mayo Elbow Performance Score values, 14 (77%) little or no functional impairment, and 11 (61%) little or no pain. Mean motion arcs were 100° in flexion-extension and 143° in pronation-supination. Mean elbow strength in flexion and mean wrist strength were 67% and 86%, respectively, of those on the contralateral normal side. Radio-lucent lines were visible around the prosthesis in 5 patients, radial neck osteolysis in 10 patients, and capitellar erosion in 7 patients. Seven patients each experienced a complication. Early revision surgery to treat elbow instability was required in 6 patients.

DISCUSSION

Outcomes after Guepar(®) bipolar radial head prosthesis implantation were disappointing in patients with complex radial head fractures seen in the acute or chronic setting. The associated injuries to bones and ligaments and the measures taken to repair them influence the prognosis. The complication rate is non-negligible and seems to increase over time.

LEVEL OF EVIDENCE

IV, retrospective study.

Misses and errors in upper extremity trauma radiographs

OBJECTIVE

The article reviews a select group of traumatic upper extremity injuries that can be easily misinterpreted on radiographs.

CONCLUSION

The awareness of these specific injuries and an understanding of their underlying pathophysiology and the role that radiographs can play in their evaluation will give the reader the best opportunity to make the important imaging findings and guide appropriate treatment.

Radiocapitellar joint contact pressures following radial head arthroplasty

PURPOSE

To determine the radial head arthroplasty length that best replicates the native radiocapitellar contact pressure.

METHODS

Eight cadaveric elbows (4 matched pairs) with an average age of 73 years were tested. All specimens were ligamentously stable and without visible cartilage wear. Radiocapitellar contact pressures were digitally analyzed during simulated joint loading at 0°, 45°, and 90° of elbow flexion and neutral rotation in the intact specimens and after ligament-preserving radial head arthroplasty at -2 mm, 0 mm, and +2 mm of the native length. The results were analyzed using 1-way analysis of variance and post hoc Tukey pairwise comparison tests.

RESULTS

Paired analysis demonstrated significantly decreased mean contact pressures when comparing the native versus the minus 2 groups. Significantly decreased maximum contact pressures were also noted between the native and the minus 2 groups. Examining the mean contact pressures showed no significant difference between the native and the zero group and the native and the plus 2 groups. As for the maximum contact pressures, there was also no significant difference between the native and the zero group and the native and the plus 2 group.

CONCLUSIONS

Up to 2 mm of overlengthening may be tolerated under simulated loading conditions without significantly increasing contact pressures of the radiocapitellar joint. Surgeons can use this knowledge along with radiographic parameters and intraoperative examination of elbow stability to gauge the appropriate size of the radial head implant to be used in order to decrease the risk of overstuffing the joint and minimizing radiocapitellar chondral wear.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Single-staged treatment using a standardized protocol results in functional motion in the majority of patients with a terrible triad elbow injury

BACKGROUND

Terrible triad injuries of the elbow, defined as elbow dislocation with associated fractures to the radial head and coronoid, are associated with stiffness, pain, and loss of motion. Studies to date have consisted of small sample sizes and used heterogeneous surgical techniques, which render comparisons difficult and unreliable.

QUESTIONS/PURPOSES

In a group of patients treated under a standard surgical protocol, we sought to determine the early dislocation rate, the range of motion in those not undergoing secondary procedures, the frequency and types of secondary surgical interventions required, the difference in motion between those undergoing secondary surgery and those who did not, and the frequency of heterotopic ossification and patient-reported stiffness.

METHODS

Patients underwent a surgical protocol that involved fixing the coronoid, fixing the radial head if possible, otherwise performing radial head arthroplasty, and repairing the lateral ligamentous structures. Patients were excluded if ipsilateral upper extremity fractures from the humerus to the distal forearm were present. Fifty-two patients had a minimum followup of 6 weeks and were included for the early dislocation rate, and 34 of these (65%) had a minimum of 6 months followup and were included for the rest of the data. Eighteen of the 52 (35%) were considered lost to followup because they were seen for less than 6 months postsurgically and were excluded from further analysis. Chart review was performed to determine the presence of early dislocation within the first 6 weeks after surgery, range of motion in patients not requiring a secondary procedure, the frequency and types of secondary procedures required, the range of motion before and after a secondary procedure if it was required, and postoperative stiffness. Postoperative radiographs were analyzed to determine the presence and severity of heterotopic ossification.

RESULTS

One of 52 patients sustained a dislocation within the first weeks of surgery (1.9%). Those not undergoing a secondary procedure were able to achieve a flexion arc of 110° and a supination-pronation arc of 148°. Nine of 34 patients (26%) underwent a secondary surgical procedure with stiffness, heterotopic ossification, and ulnar neuropathy being the most common surgical indications. Before secondary surgical procedures, patients had a flexion arc of 57° and a supination-pronation arc of 55°, which was less than those only requiring primary surgery alone (p < 0.001). After secondary surgery, patients were able to achieve a flexion arc of 96° and a supination-pronation arc of 124°, which was not different from those who did not undergo reoperation (p = 0.09 and p = 0.08, respectively). Twenty-eight of 34 patients demonstrated evidence of heterotopic ossification on radiographs, whereas 20 patients, including all nine undergoing secondary procedures, reported stiffness at the elbow.

CONCLUSIONS

Using a standardized surgical protocol, a low early dislocation rate was observed, although stiffness remains a challenge. Many patients who initially do not attain functional range of motion can usually attain this after secondary procedures aimed at removing the heterotopic ossification.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See guidelines for authors for a complete description of levels of evidence.

Anconeus interposition arthroplasty: mid- to long-term results

BACKGROUND

Radiocapitellar arthritis and/or proximal radioulnar impingement can be difficult to treat. Interposition of the anconeus muscle has been described in the past as an alternative option in managing arthritis, but there are little published data about relief of pain and restoration of function over the long term in patients treated with this approach.

QUESTIONS/PURPOSES

We sought (1) to determine whether interposition of the anconeus muscle in the radiocapitellar and/or proximal radioulnar joint relieves pain and restores elbow function; and (2) to identify complications and reoperations after anconeus interposition arthroplasty.

METHODS

Between 1992 and 2012, we surgically treated 39 patients having radiocapitellar arthritis and/or proximal radioulnar impingement with an anconeus interposition arthroplasty. These were performed for situations in which capitellar and/or radial head pathology was deemed not amenable to implant replacement. We had complete followup on 29 of them (74%) at a minimum of 1 year (mean, 10 years; range, 1-20 years). These 29 patients (21 males, eight females) had interposition of the anconeus muscle at the radiocapitellar joint (10 elbows), the proximal radioulnar joint (two elbows), or both (17 elbows). Their mean age at the time of surgery was 39 years (range, 14-58 years). The reasons for the previous determination or the indications included lateral-side elbow symptoms after radial head resection (eight elbows), failed internal fixation of radial head fracture (two elbows), failed radial head replacement with or without capitellar replacement (four elbows), osteoarthritis and Essex-Lopresti injury (six elbows), failed internal fixation of distal humeral fracture involving the capitellum (two elbows), posttraumatic osteoarthritis involving the lateral compartment (one elbow), lateral compartment osteoarthritis associated with chondropathies (three elbows), and primary osteoarthritis affecting the lateral compartment (three elbows). Patient-reported outcome tools included the quick-Disabilities of the Arm, Shoulder and Hand (quick-DASH) and the Mayo Elbow Performance Score (MEPS); we also performed a chart review for complications and reoperations.

RESULTS

During the followup duration, the mean MEPS was significantly improved from (mean ± SD) 64 ± 17 points before surgery to 82 ± 14 points after surgery (p < 0.001) with 21 elbows (72%) graded as excellent or good at most recent followup. The mean quick-DASH score was 24 ± 17 points (n = 25) at latest evaluation. Two patients (7%) had perioperative complications, including wound dehiscence (one elbow) and transient posterior interosseous nerve palsy (one elbow). Seven patients (24%) underwent additional surgery.

CONCLUSIONS

Anconeus arthroplasty provides a reasonable surgical alternative in the armamentarium of procedures to address pathology at the radiocapitellar and/or proximal radioulnar joint. This procedure is especially attractive when other alternatives such as radial head replacement may be problematic secondary to capitellar erosion or marked proximal radius bone loss.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The bicipital tuberosity and distal radius are unreliable landmarks for radial head implant alignment

BACKGROUND

As more anatomic asymmetric radial head implants emerge, it is necessary to determine the optimal landmarks to ensure correct rotational orientation. The bicipital tuberosity and distal radius are possible bony landmarks that can be used for rotational alignment of asymmetric prostheses; however, they have not been validated. The purpose of this study was to evaluate the reliability of the bicipital tuberosity and distal radius as rotational landmarks for orientation of asymmetric radial head prostheses.

METHODS

Measurements were made from computer tomography scans of 50 elbows in order to determine the rotational relationships between the radial head, bicipital tuberosity, biceps tendon footprint, and distal radius.

RESULTS

The maximum radial head diameter was oriented 65° ± 28° from the bicipital tuberosity, 119° ± 38° from the biceps tendon footprint, 82° ± 29° from the radial styloid, and 76° ± 28° from the volar surface of the distal radius. All of these landmarks had a significantly greater variance than a proposed acceptable clinical tolerance of 10° (P < .001).

CONCLUSION

The results demonstrate that the measured landmarks show no consistent rotational relationship with the maximum diameter of the radial head. In order to maximize the utility of more anatomic asymmetric radial head implant systems, further studies are necessary to identify more reliable rotational landmarks to ensure optimal implant positioning.

Terrible triad of the elbow

The terrible triad of the elbow is a difficult injury with historically poor outcomes. Improved experience, techniques, and implants have advanced to the point where restoration of elbow stability can be expected. Careful attention to each destabilizing element of the injury pattern is essential and places high demands on the surgeon's mastery of the anatomic complexity of the elbow. Technically, the surgeon must bring every skill to bear, as soft tissue techniques, fracture repair, and joint arthroplasty are routinely required to adequately treat these complex constellations of injury.

Treatment of radial head and neck fractures: in favor of anatomical reconstruction

Radial head fractures represent the most common elbow fractures. Undisplaced fractures usually occur in isolation and can be treated nonsurgically. Displaced fractures should be treated surgically. Simple two-part fractures can easily be handled by osteosynthesis, but comminuted fractures pose a major problem for reconstruction. As the radial head is an important stabilizer of the elbow joint-especially in the context of concomitant ligamentous injuries-its resection may lead to pain, limited range of motion, and instability. Therefore, radial head resection is not recommended for the acute situation and open reduction internal fixation (ORIF) or prosthetic replacement should be aimed for. Complications such as secondary loss of fixation, radial head necrosis, and nonunion due to insufficient stability of the osteosynthesis have often been described. Therefore, prosthetic replacement is recommended if stable reconstruction is impossible. With the development of new locking plates especially designed for the maintenance of radial head fractures, the indications for osteosynthesis may be extended. As radial head fractures are complicated by a high percentage of ligamentous injuries and concomitant elbow fractures such as the coronoid, capitellum, and proximal ulna, these additional injuries have to be taken into account. The current treatment concepts are discussed within this paper.

Radiocapitellar stability: the effect of soft tissue integrity on bipolar versus monopolar radial head prostheses

INTRODUCTION

Radiocapitellar stability depends, in part, on concavity-compression mechanics. This study was conducted to examine the effects of the soft tissues on radiocapitellar stability with radial head prostheses.

HYPOTHESIS

Monopolar radial head implants are more effective in stabilizing the radiocapitellar joint than bipolar radial head prostheses, with the soft tissues intact or repaired.

MATERIALS AND METHODS

Twelve fresh frozen elbow specimens were used to evaluate radiocapitellar stability with monopolar and bipolar radial heads. The study variables focused on varying soft tissue conditions and examined the mean peak subluxation forces put forth by each prosthesis design.

RESULTS

With the soft tissues intact, the mean peak force resisting posterior subluxation depended significantly on the radial head used (P = .03). Peak force was greatest for the native radial head (32 ± 7 N) and least with the bipolar prosthesis (12 ± 3 N), with the monopolar prosthesis falling in between (21 ± 4 N). The presence of soft tissues significantly affected the bipolar implant's ability to resist subluxation, though it did not significantly impact the native or monopolar radial heads.

DISCUSSION

This study reveals the dependence of radiocapitellar stability on soft tissue integrity, particularly for bipolar prostheses. Overall, monopolar prostheses have a better capacity to resist radiocapitellar subluxation.

CONCLUSION

From a biomechanical perspective, the enhancement of elbow stability with a monopolar radial head prosthesis is superior to that with a bipolar design. This is especially true when the integrity of the soft tissues has been compromised, such as in trauma.

Effect of coronal shear fractures of the distal humerus on elbow kinematics and stability

BACKGROUND

Coronal shear fractures of the distal humerus can include some or all of the cartilaginous and bony surface. Fixation is preferred, but severe comminution, nonunion, and avascular necrosis may mandate excision. The amount of distal humerus that is safe to excise is unknown. This study examined the effect of excision of the capitellum and trochlea on elbow kinematics and stability with intact collateral ligaments.

METHODS

Eight cadaveric arms were mounted in an upper extremity joint testing system. Electromagnetic receivers on the radius and ulna enabled quantification of ulnohumeral and radiocapitellar kinematics. The distal humeral articular surface was sequentially excised to replicate clinically relevant coronal shear fractures, leaving the collateral ligaments undisturbed. The arms underwent simulated active flexion in vertical and valgus-loaded positions, and passive forearm rotation in the vertical position.

RESULTS

In the vertical position, sequential excision of the articular surface increased valgus angulation during active flexion (P < or = .04), and excision of the entire articular surface increased ulnar external rotation compared to the intact elbow (P < or = .02). In the valgus position, excisions involving the trochlea increased valgus angulation for active flexion (P < or = .04). The radial head moved distal, posterior, and medial on the capitellum with some or all of the trochlea excised (P < or = .02).

DISCUSSION

While the capitellum alone does not contribute to elbow stability, the trochlea has an important role. Excision of the trochlea resulted in multiplanar instability of the ulnohumeral and radiocapitellar joints. Therefore, excision of an irreparable capitellum fracture may be considered if collateral ligaments are intact, while excision of some or all of the trochlea may not.

On-table reconstruction of comminuted fractures of the radial head

The most widely accepted treatment for comminuted fractures of the radial head is either the excision or open reduction and internal fixation. The purpose of the present study is to evaluate the value of an 'on-table' reconstruction technique in severely comminuted fractures of the radial head. In this study, two patients with a Mason type-III and four patients with a Mason type-IV radial-head fracture were treated with 'on-table' reconstruction and fixation using low-profile mini-plates. After a mean follow-up of 112 months (47-154 months), the mean elbow motion was 0-6-141 degrees extension flexion with 79 degrees of pronation and 70 degrees of supination. The mean Broberg and Morrey functional rating score was 97.0 points, the Mayo Elbow Performance Index was 99.2 points and the mean Disabilities of the Arm, Shoulder, and Hand (DASH) Outcome Measure score was 1.94 points. One patient had symptoms of degenerative changes, with a slight joint-space narrowing. There were no radiographic signs of devitalisation at final examination. Comminuted fractures of the radial head, which would otherwise require excision, can be successfully treated with an 'on-table' reconstruction technique.

Radiocapitellar joint stability with bipolar versus monopolar radial head prostheses

BACKGROUND

Bipolar and monopolar designs are both available for replacement of the radial head. Few data exist comparing the biomechanical characteristics of these 2 quite different prostheses. This study evaluated the relative contribution to radiocapitellar stability by concavity compression with these 2 types of radial head prostheses.

METHODS

The study used 12 fresh frozen elbow cadavers. The capitellum of the distal humerus and 3 different conditions of radial head (native, monopolar and bipolar) were tested for radiocapitellar joint stability.

RESULTS

The monopolar metallic head and the native radial head behaved similarly regarding resistance to subluxation. The bipolar head behaved in an entirely opposite manner than the native and monopolar head and actually acted to facilitate subluxation.

CONCLUSIONS

Mobility of radial head components, such as in the bipolar radial head, has a compromising effect on the concavity compression stability of the radiocapitellar joint. A monopolar implant is more effective in stabilizing the radiocapitellar joint than a bipolar radial head prosthesis.

Complex varus elbow instability: a terrible triad model

HYPOTHESIS

The terrible triad is a debilitating injury that involves elbow dislocation with injury to the lateral collateral ligament (LCL) complex, the radial head, and the coronoid process. This study investigated the role of these components in varus stability of the elbow.

MATERIALS AND METHODS

We investigated the role of these components in varus stability of the elbow using 10 cadaveric fresh frozen upper extremities. The testing order allowed each of four states to be tested (intact, LCL complex deficient or repaired, radial head resected or replaced) at two flexion angles and multiple coronoid resection levels. Values for restraining load (newtons [N]) at 1.5 cm of varus displacement were obtained on a materials testing machine.

RESULTS

Beyond a 50% loss of the coronoid process, neither repair of the LCL nor replacing the radial head alone resulted in a statistically significant increase in varus stability. For a loss of the coronoid process between 67-75%, repair of the LCL and replacement of the radial head showed improved stability over repair alone, or radial head replacement alone. For loss of the coronoid beyond 75%, even repair of the LCL and replacement of the radial head did not improve varus stability of the elbow.

CONCLUSION

These findings provide a biomechanical basis for aggressive treatment of coronoid fractures as a component of the terrible triad injury.

LEVELS OF EVIDENCE

Basic science study.

Anatomy and biomechanics of the elbow

The elbow is a complex, highly constrained joint that provides critical range of motion to the upper extremity needed for performing the normal activities of daily living. The elbow is protected by a fortress of individual static and dynamic constraints that function together to provide stability. Knowing the identity and specific functions of each stabilizing structure facilitates appropriate diagnosis and treatment of the acutely injured elbow.

Short-term to medium-term outcomes of cemented Vitallium radial head prostheses after early excision for radial head fractures

Studies show that the radial head is a significant stabilizer to valgus and varus stresses and external rotatory stability. We review the outcomes of patients who had radial head replacement in our institution. Six patients with Mason-Johnston type III or IV radial head fractures underwent radial head replacement and were evaluated by radiologic and clinical assessment. The American Shoulder and Elbow Surgeons score, DASH (Disabilities Arm, Shoulder and Hand) score, and Broberg and Morrey Performance Index were calculated. Average follow-up was 29.7 months. The Broberg and Morrey score was excellent for 1 patient, good for 3, fair for 1, and poor for 1. Complications included prosthetic loosening in 4 patients and 1 patient each with ulnar neuropathy, heterotrophic ossification, and wrist pain. Outcomes did not necessarily correlate with the severity of the initial injury or the eventual range of motion. Longer follow-up is required to see if the radiologic loosening will lead to clinical instability.

Clinical biomechanics of the elbow

This paper describes the biomechanics of the articulations of the elbow joint that is relevant to therapists who design rehabilitation programs for patients following injuries or surgeries to the elbow. Individual and combined joint movements required for function such as activities of daily living are discussed, including normal arthrokinematics and the components that contribute to joint stability. The strain behavior of the nerves that cross the elbow is also reviewed. Therapists will understand the complexities of the biomechanics of the elbow that is necessary to design safe and effective rehabilitation programs.