Lateral ulnohumeral joint space widening is not diagnostic of radial head arthroplasty overstuffing

Postoperative Elbow Instability: Options for Revision Stabilization

Persistent and recurrent postoperative elbow instability includes a spectrum of pathologies ranging from joint incongruity and subluxation to dislocation. Restoration of osseous anatomy, particularly the coronoid, is a priority in restoring elbow alignment and maintaining ulnohumeral joint stability. After managing bony deficiencies, soft-tissue and ligamentous structures are typically addressed. When required, both static and dynamic adjunctive stabilization procedures have been described, which aid in maintaining a concentric reduction. In these complex procedures, both complication avoidance and early recognition of postoperative complications assist in obtaining a good result. In this review, we discuss current treatment options for revision stabilization for patients with persistent and recurrent elbow subluxation or dislocation after primary stabilization.

Intraoperative visualization of the posterolateral ulnohumeral joint space is reliable to indicate overlengthening in radial head arthroplasty

INTRODUCTION

Avoiding overlengthening in radial head arthroplasty (RHA) is essential for the prognosis of the elbow joint. An overlengthening from 2 mm is visible due to widening of the anterolateral ulnohumeral joint space but intraoperatively, this particular joint space is difficult to visualize. The commonly used Kocher approach allows visualization of the posterolateral joint space without additional instruments or further surgical release of the already unstable elbow. The aim of our study was to investigate whether the visualization of the posterolateral joint space is also a reliable method to indicate overlengthening in RHA.

MATERIAL AND METHODS

RHA was performed in five human cadaveric specimens with the forearm, wrist, and hand intact. The lateral ligament complex was detached and an anatomic transosseous refixation was performed. Six stages of implantation heights were documented: native joint (1), RHA at the anatomic height (2), + 2 mm (3), + 4 mm (4), + 6 mm (5) and - 2 mm (6). Macroscopic measurement and digital image analysis of the posterolateral and anterolateral ulnohumeral joint spaces were performed.

RESULTS

All stages of overlengthening showed a significant increase in posterolateral and anterolateral joint space widening (p < 0.05). The posterior and anterior joint space showed excellent intraclass correlation.

CONCLUSION

Visualization of the posterolateral aspect of the ulnohumeral joint space is a reliable indicator for overlengthening in RHA without further compromising an already unstable elbow. Correlation to the findings of the anterolateral ulnohumeral joint space in different implants leads to the assumption that visualization of either the anterior or posterior ulnohumeral joint space is universally applicable to determine overlengthening in RHA, regardless of the type of the radial head implant.

Mid-term outcome following radial head arthroplasty in acute trauma: risk factors for poor outcome

BACKGROUND

The aims of this study were to evaluate the outcomes of a single type of radial head implant in a large cohort of patients at mid-term follow-up and to determine the associated risk factors for inferior functional outcomes.

METHODS

We performed a retrospective follow-up assessment of 65 patients (33 women and 32 men; mean age, 53.3 years [range, 22-81 years]) who underwent radial head arthroplasty (RHA) for acute trauma between 2012 and 2018, after a minimum follow-up period of 3 years. The Mayo Elbow Performance Score, Oxford Elbow Score, Disabilities of the Arm, Shoulder and Hand score, and Mayo Modified Wrist Score were evaluated, and all available radiographs were analyzed. All complications and revision procedures were assessed. Bivariate and multivariate regression analyses were performed to identify potential risk factors for a poor outcome following RHA.

RESULTS

After an average follow-up period of 4.1 years (range, 3-9.4 years), the mean Mayo Elbow Performance Score was 77.2 (standard deviation [SD], 18.9); mean Oxford Elbow Score, 32.0 (SD, 10.6); mean Mayo Modified Wrist Score, 74.6 (SD, 13.7); and mean Disabilities of the Arm, Shoulder and Hand score, 29.0 (SD, 21.2). Average range of motion measured 10° (SD, 15°) in extension, 125° (SD, 14°) in flexion, 81° (SD, 14°) in pronation, and 63° (SD, 24°) in supination. The overall complication and reoperation rates were 38.5% and 30.8%, respectively, with severe elbow stiffness being the most common reason for revision. Patient age >50 years, the use of an external fixator, the presence of accompanying medial collateral ligament injuries, and the development of higher-grade osteoarthritis were associated with a poor outcome.

CONCLUSION

Satisfactory medium-term outcomes can be achieved using a monopolar, long-stemmed RHA in patients with acute trauma. However, complication and revision rates are high, frequently leading to inferior outcome scores. Additionally, a higher patient age, the use of an external fixator, the presence of accompanying medial collateral ligament injuries, and the occurrence of higher-grade osteoarthritis were associated with a poor outcome; these factors should raise awareness by the treating trauma surgeon.

Radial head replacement - A comprehensive review

Background

Radial head fractures represent 1-4% of all adult fractures and 1/3rd of elbow fractures (Kaas et al., 2010). Radial head is an important secondary stabilier of the elbow. The aim of the treatment of radial head fractures is to achieve stability and good functional outcome. Radial head replacement (RHR) is indicated when robust reconstruction and fixation of the fracture fragments is not possible.

Methods

This article explores history and evolution, anatomical considerations, biomechanics, implant designs, indications, surgical outcomes and controversies in radial head replacement based on current evidence.

Results

There is a wide range of RHR designs available without conclusive evidence to support the superiority of one design over the other. Ranges of motion, functional outcomes and complication were comparable among different designs with a high incidence of complications reported in many studies.

Conclusion

RHR remains a good option in unreconstructible radial head fractures, with potential to regain excellent function. It is imperative to continue with the quest to innovate and improve on current designs, to reduce complications in the long term.

Relationship between measurements of ipsilateral capitellum and prosthetic radial head size

Background

Selecting the correct size of head component is challenging in radial head arthroplasty, particularly in comminuted fractures. This study aimed to investigate the relationship between measurements of the ipsilateral capitellum and the prosthetic radial head size, which may be used to predict the size of the radial head prosthesis preoperatively.

Methods

Our study enrolled all patients who underwent radial head arthroplasty at Beijing Jishuitan Hospital. Demographic, injury-related and radiographic data were collected. The prosthetic radial head size was recorded from the surgical notes. Three-dimensional models of preoperative CT scans were reconstructed, on which the lateral capitellar diameter, the capitellar width and the width between the capitellum and trochlea were measured. The correlations between measurements of the ipsilateral capitellum and the prosthetic radial head size were evaluated, and linear regression equations were established.

Results

The study enrolled 37 patients, with an average age of 42.8 ± 11.5 years and a male–female ratio of 20:17. The median diameter of the radial head prostheses was 22 (20, 22) mm. The average lateral capitellar diameter was 20.71 ± 1.93 mm, the mean capitellar width was 14.90 ± 1.40 mm, and the mean width between the capitellum and trochlea was 19.29 ± 1.78 mm. The lateral capitellar diameter (R = 0.820, P < 0.001), the capitellar width (R = 0.726, P < 0.001) and the width between the capitellum and trochlea (R = 0.626, P < 0.001) were significantly positively correlated with the size of the radial head prosthesis. The linear regression equation between the lateral capitellar diameter and the size of the radial head prosthesis was calculated and defined as follows: D = 7.44 + 0.67*d (D: diameter of radial head prosthesis; d: lateral capitellar diameter; and adjusted R2 = 0.719, P < 0.001).

Conclusions

There are positive correlations between the anatomical parameters of the ipsilateral capitellum and the prosthetic radial head size. The lateral capitellar diameter can be measured on three-dimensional CT preoperatively to predict the size of the radial head prosthesis intraoperatively.

The Unsalvageable Radial Head in Patients Aged 30 Years and Younger

PURPOSE

Concern exists regarding the use of radial head arthroplasty (RHA) in younger patients. This study assessed clinical, functional, and radiographic outcomes of RHA in patients aged 30 years and younger.

METHODS

A retrospective review identified 26 elbows that underwent a smooth stem modular RHA in patients aged 30 years and younger at a median follow-up of 3.3 years clinically and 2.9 years radiographically. The mean age was 24 ± 5 years. Indications were acute trauma in 13 patients and chronic pathologies in the remaining 13, and these 2 groups were evaluated separately. Patients underwent clinical, functional, and radiographic evaluation.

RESULTS

Average arc of motion was 137° ± 16° in the cohort with acute trauma and 120° ± 24° in the cohort with chronic pathologies. Mean Patient-Rated Elbow Evaluation scores were 23 ± 18 (acute) and 31 ± 19 (chronic). Mean Quick Disabilities of the Arm, Shoulder, and Hand scores were 18 ± 15 (acute) and 23 ± 20 (chronic). Average Mayo Elbow Performance Index scores were 90 ± 9 (acute) and 80 ± 13 (chronic). Severe capitellar erosion was present in 1 patient (4%) in the cohort with chronic pathologies. Radiographic stem lucency was seen in all cases with 10 of these (38%) graded as severe. Moderate-to-severe ulnohumeral arthritis developed in 4 patients (15%), 3 of whom were in the chronic reconstruction group. Two patients (8%) required reoperation, 1 for persistent instability and 1 for stiffness, both in the cohort with chronic pathologies.

CONCLUSIONS

For acute trauma and challenging chronic conditions involving the radial head in patients aged 30 years and younger, a smooth stem modular RHA is an option. Although reoperation rates based on this series are low, osteoarthritis is common when used for posttraumatic conditions and severe radiographic stem lucency was seen in greater than one-third of patients. These concerning features warrant close follow-up, and further long-term outcomes are needed.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Optimal Prosthesis Sizing for Radial Head Arthroplasty: A Review of Current Evidence and Guidelines

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Radial head arthroplasty is a viable surgical option when a radial head fracture cannot be reconstructed. Radial head arthroplasty provides a load-bearing articular structure against the capitellum in unstable fractured elbows.

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Studies have emphasized the importance of choosing the correct implant size to replicate the native radial head anatomy, citing various consequences of improperly sized radial head prostheses. Overstuffing of the radiocapitellar joint, or lengthening of the radius, has been extensively studied because of its detrimental effects on elbow biomechanics, but other types of improper sizing also have negative consequences.

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In the setting of severe fracture-dislocation or revision surgery, anatomic landmarks that are useful for prosthesis sizing often are missing. Various methods have been described to provide guidance for the accurate sizing of a prosthetic radial head; a retrieved radial head, the proximal edge of the lesser sigmoid notch, the radiocapitellar synovial fold, and the ulnohumeral joint space all represent useful references.

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Intraoperative radiographic examination is an important step while assessing implant size, including the height of the prosthetic radial head.

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Since no single method is perfect on its own, the surgeon should combine as many reference measures as possible, both before and during the procedure, for accurate prosthesis sizing in order to achieve successful outcomes.

Risk Factors for Revision Surgery Following Radial Head Arthroplasty without Cement for Unreconstructible Radial Head Fractures: Minimum 3-Year Follow-up

BACKGROUND

Revision rates following radial head arthroplasty (RHA) for unreconstructible radial head fractures (RHFs) differ vastly in the literature, and little is known about the risk factors that are associated with revision surgery. The purposes of this study were to assess the revision rate following RHA and to determine the associated risk factors.

METHODS

A total of 122 patients (mean age, 50.7 years; range, 18 to 79 years) with 123 RHAs who underwent RHA for unreconstructible RHFs between 1994 and 2014 and were ≥3 years out from surgery were included. Demographic variables, injury and procedure-related characteristics, radiographic findings, complications, and revision procedures were assessed. Cox regression analysis was performed to identify the risk factors that were associated with revision surgery following RHA.

RESULTS

The median follow-up for the study cohort was 7.3 years (interquartile range [IQR], 5.1 to 10.1 years). All of the patients had unreconstructible RHFs: Mason-Johnston type-IV injuries were the most prevalent (80 [65%]). One or more associated osseous or ligamentous injuries were seen in 89 elbows (72.4%). The median time to surgery was 7 days (IQR, 3 to 11 days). Implanted prostheses were categorized as rigidly fixed (65 [52.8%]) or loosely fixed (58 [47.2%]). A total of 28 elbows (22.8%) underwent revision surgery at a median of 1.1 years (IQR, 0.3 to 3.8 years), with the majority of elbows (17 [60.7%]) undergoing revision surgery within the first 2 years. The most common reason for revision surgery was painful implant loosening (14 [29.2% of 48 complications]). Univariate Cox regression suggested that Workers' Compensation claims (hazard ratio [HR], 5.48; p < 0.001) and the use of an external fixator (HR, 4.67; p = 0.007) were significantly associated with revision surgery.

CONCLUSIONS

Revision rates following RHA for unreconstructible RHFs are high; the most common cause for revision surgery is painful implant loosening. Revision surgeries are predominantly performed within the first 2 years after implantation, and surgeons should be aware that Workers' Compensation claims and the use of an external fixator in management of the elbow injury are associated with revision surgery.

LEVEL OF EVIDENCE

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

Elbow Fracture-Dislocations: Determining Treatment Strategies

Elbow dislocations represent common injuries. A quarter of these injuries involve at least 1 fracture. The sequel of elbow fracture-dislocations can be fraught with complications, including recurrent instability, posttraumatic arthritis, elbow contracture, and poor functional results. The 3 main patterns of injury are valgus posterolateral rotatory instability, varus posteromedial rotatory instability, and transolecranon fracture-dislocation. This article discusses each pattern individually, including the anatomy, the typical injury pattern, and treatment strategies. It also discusses common complications that can occur.

Radiographic assessment of overlengthening of the MoPyC radial head prosthesis: a cadaveric study

INTRODUCTION

The aim of this study was to evaluate a radiographic measurement method for assessment of overlengthening of the MoPyC radial head prosthesis.

MATERIALS AND METHODS

Seven cadaver specimens were studied in ten stages: native specimen (1), radial head resection (2), and implantation of the MoPyC radial head prostheses (Bioprofile, Tornier, Montbonnot-Saint-Martin, France) in four increasing length (correct length, overlengthening of 1.5 mm, 3 mm, and 5 mm) with an intact medial collateral ligament (MCL 3-6) and following transection of the MCL (7-10). The radiographic measurement method according to Athwal et al. was evaluated to detect overlengthening. Statistical analysis included calculation of the diagnostic accuracy of the radiographic method.

RESULTS

The radiographic measurement method correctly determined the size of the radial head prosthesis within ± 1 mm in 224 of 336 scenarios (67%) and within ± 2 mm in 320 of 336 scenarios (95%). With a threshold value of ≥ 1 mm, the overall diagnostic sensitivity for detecting overlengthening when it was present and was 90% and the specificity was 79%. The sensitivity was higher with increasing size of the prosthesis: in cases with overlengthening of 1.5 mm, the sensitivity was 76%, with an overlengthening of 3 mm, the sensitivity was 95%, and with an overlengthening of 5 mm, the sensitivity was 100%.

CONCLUSION

The radiographic measurement method of Athwal et al. can be used to estimate and to diagnose the magnitude overlengthening of the MoPyC radial head prosthesis. However, the sensitivity is limited (76%) in cases with a small amount of overlengthening of 1.5 mm.

Validation of a Simple Overlay Device to Assess Radial Head Implant Length

PURPOSE

A simple overlay device (SOD) was developed to measure radial head implant length. The purpose of this study was to determine the accuracy and reliability of this device for measuring experimental radial head implant length.

METHODS

Five fresh frozen cadavers were implanted with sequentially longer implants, adjusted by neck length (0, 2, 4, and 8 mm). Fluoroscopic images were obtained in 4 forearm positions: anteroposterior in supination in full extension, anteroposterior in pronation in full extension, supinated in 45° of flexion, and neutral in 45° of flexion. The SOD measurements (made by 2 observers) were compared with the native original radial head (control) to assess implant length. In addition, gapping of the ulnohumeral joint space was measured for comparison purposes.

RESULTS

The measured radial head and neck lengths for the specimens were 33, 39, 31, 34, and 42 mm. The difference between the actual radial head and neck lengths and those measured with the SOD template averaged less than 2 mm for all 4 collar sizes, except in 1 measurement in which the bicipital tuberosity could not be visualized. The median intraclass correlation coefficients for observer 1 compared with the SOD were 0.94 to 0.99. The median intraclass correlation coefficients between observers were 0.88 to 0.95. For both observers, elbow position, collar height, and the 2 variables combined did not significantly affect the SOD values. The other method that was evaluated, that of measurement of the ulnohumeral joint space, had higher interobserver variability versus the SOD, and allowed detection of lengthening of over 4 mm.

CONCLUSIONS

The SOD is a reliable method for simply assessing radial head length with radiographs and can accurately detect 2 mm or more of proximal radial lengthening.

CLINICAL RELEVANCE

The SOD is a simple and accurate method that can help to optimize radial head sizing.

The radiocapitellar synovial fold: a lateral anatomic landmark for sizing radial head arthroplasty

BACKGROUND

Successful radial head arthroplasty relies on reproduction of anatomy. We hypothesized that the radiocapitellar synovial fold could serve as a reference point in radial head prosthesis sizing. Our study aimed to define the relationship between the synovial fold and the radial head in elbows with and without lateral ulnar collateral ligament (LUCL) injury.

MATERIALS AND METHODS

We performed magnetic resonance imaging evaluation of 34 elbows to determine the normal relationship between the radiocapitellar synovial fold and the radial head. Next, we used cadaveric dissections to evaluate the anatomic relationships with the LUCL intact and disrupted, as well as in the setting of sizing with a radial head prosthesis. The fold-to-radial head distance (FRHD) was measured on all images and analyzed to determine the relationship of the synovial fold and radial head.

RESULTS

The FRHD in cadavers with an intact LUCL and native radial head measured an average of 1.5 mm proximal to the radial head. With the LUCL disrupted and a native radial head, the FRHD measured an average of 1.2 mm proximal to the radial head. The mean difference between the groups was 0.5 mm (P = .031), suggesting that the fold migrated distally in the cadavers with a disrupted LUCL.

CONCLUSION

The radiocapitellar synovial fold may be a helpful landmark for radial head sizing. The synovial fold is always just proximal to the articular surface of the radial head. Using this information, the surgeon can prevent overlengthening as the implant should not be placed proximal to the fold.

Long-term results of the lateral resurfacing elbow arthroplasty

Aims

The aim of this study was to report the long-term outcome and implant survival of the lateral resurfacing elbow (LRE) arthroplasty in the treatment of elbow arthritis.

Patients and Methods

We reviewed a consecutive series of 27 patients (30 elbows) who underwent LRE arthroplasty between December 2005 and January 2008. There were 15 women and 12 men, with a mean age of 61 years (25 to 82). The diagnosis was primary hypotrophic osteoarthritis (OA) in 12 patients (14 elbows), post-traumatic osteoarthritis (PTOA) in five (five elbows) and rheumatoid arthritis (RA) in ten patients (11 elbows). The mean clinical outcome scores including the Mayo Elbow Performance Score (MEPS), the American Shoulder and Elbow Surgeons elbow score (ASES-e), the mean range of movement and the radiological outcome were recorded at three, six and 12 months and at a mean final follow-up of 8.3 years (7.3 to 9.4). A one sample t-test comparing pre and postoperative values, and survival analysis using the Kaplan-Meier method were undertaken.

Results

A statistically significantly increased outcome score was noted for the whole group at each time interval. This was also significantly increased at each time in each of the subgroups (OA, RA, and PTOA). Implant survivorship was 100%.

Conclusion

We found that the LRE arthroplasty, which was initially developed for younger patients with osteoarthritis, is an effective form of surgical treatment for a wider range of patients with more severe degenerative changes, irrespective of their cause. It is therefore a satisfactory alternative to total elbow arthroplasty (TEA) and has lower rates of complications in the subgroups of patients we have studied. It does not require activities to be restricted to the same extent as following TEA. Based on this experience, we now recommend LRE arthroplasty rather than TEA as the primary form of implant for the treatment of patients with OA of the elbow. Cite this article: Bone Joint J 2018;100-B:338-45.

Radial head prosthesis: surgical tips and tricks

Radial head prostheses (RHP) have been developed to decrease the complications rate following a radial head resection surgery. The aim of the RHP is to replicate the physiological radiocapitellar tracking, reproducing the mechanical function of the native radial head: to stabilize the elbow and to shear the forces passing through the elbow along with the other stabilizers. The currently used RHP models try to achieve this target with three different prosthesis' strategies: (a) loose fit stem, (b) bipolar radial head or (c) anatomical radial head. Even if the radial head fixation is the preferred technique in every possible case and the resection can be still considered a possible option, in the last years there has been a growing worldwide consensus in using the radial head replacement in patients with unfixable radial head fractures, especially if associated with complex elbow instability. However, complications after a RHP are not uncommon, and their rate is raising as long as the implants number are increasing. The main difficulties are due to the implantation technique that needs to be performed with the same attention and precision used for the replacement of all the other joints, and to the concurrent treatment of the associated lesions. A personalized postoperative rehabilitation program is essential for obtaining good results and decreasing the complications rate. Concern exists for the young age of the patients that often require a RHP: personal experience and literature analysis suggest that if the clinical and radiographic results are positive after a 6-12-month follow-up, good outcomes can be also expected at a medium- or long-term follow-up.

[Chronic ligamentous instability of the elbow]

BACKGROUND

Chronic ligamentous instability of the elbow is an important pathology as it is accompanied with pronounced dysfunction. Moreover, it represents an established risk factor for the development of osteoarthritis. Posterolateral rotatory instability (PLRI) caused by insufficiency of the lateral collateral ligament (LCL) is the most common type of chronic elbow instability and is usually a sequel of traumatic elbow dislocation. Chronic overload can lead to insufficiency of the ulnar collateral ligament (UCL) with subsequent valgus instability, especially in overhead athletes.

DIAGNOSTICS

Subjective instability and recurrent elbow dislocations are not always the main symptoms but elbow instability is instead often characterized by pain and secondary joint stiffness. Many clinical tests are available yet eliciting them can be difficult and inconclusive. A "drop sign" on lateral radiographs as well as the detection of collateral ligament injuries and joint incongruity on MRI scans can support the suspected diagnosis. In some cases, instability can only be verified by diagnostic arthroscopy.

TREATMENT

Reconstruction of the lateral ulnar collateral ligament (LUCL) for treatment of PLRI generally leads to good clinical results, yet recurrent instability remains an issue and has been reported in 8 % of cases. UCL reconstruction for chronic valgus instability leads to a return-to-sports rate of about 86 % in the overhead athlete. Ulnar neuropathy, which is seen in approximately 6 % of patients, represents the most common complication. On the rare occasion of multidirectional instability, the box-loop technique can be used for simultaneous reconstruction of the LUCL and UCL with a circumferential graft. 15 cases with promising results have been reported in literature thus far.

Retrospective cohort study on radial head replacements comparing results between smooth and porous stem designs

BACKGROUND

When necessary, radial head integrity after a fracture can be re-created by the use of a radial head arthroplasty if the radial head is judged irreparable. The purpose of this study was to compare the clinical and radiographic outcomes of metal modular radial head replacements with a smooth vs. a porous stem.

METHODS

A retrospective cohort study of radial head replacements performed in the first 4 weeks after a trauma in an adult patient at our institution between 2000 and 2014 was completed. Patients were divided into 2 groups: a porous stem group (ExploR; Biomet Orthopedics, Warsaw, IN, USA) and a smooth stem group (EVOLVE; Wright Medical Group, Memphis, TN, USA). Primary outcomes were the Disabilities of the Arm, Shoulder, and Hand and Mayo Elbow Performance Index scores. Secondary outcomes were the visual analog scale score for pain, range of motion, grip strength, and radiographic evaluations.

RESULTS

Of the 80 eligible patients, 57 agreed to participate (porous stem group, 36; smooth stem group, 21). Demographic data were similar between the 2 groups. Average follow-up was 6.3 years. Average Disabilities of the Arm, Shoulder, and Hand and Mayo Elbow Performance Index scores were similar between the 2 groups. Porous implants were more prone to osteolysis (64.3% vs. 23.5%; P = .01) and were associated with a greater loss of elbow flexion (6° vs. 1°; P = .02). The porous stem group showed a tendency toward more overstuffing (24.0% vs. 5.9%; P = .21).

CONCLUSION

Our results reveal that outcomes between smooth and porous stem metal modular radial head implants are equivalent. However, the smooth stem implant may represent the preferred option as it is associated with a lower rate of complications.

A Complicated Course of a Coronal Shear Fracture Type IV of the Distal Part of Humerus Resulting in Resurfacing Radiocapitellar Joint Replacement

Background:

Coronal shear fracture type IV of the distal part of humerus is a very rare injury with articular complexity potentially leading to posttraumatic osteoarthritis. One option for surgical treatment of advanced unicompartmental radiocapitellar osteoarthritis is resurfacing radiocapitellar joint replacement.

Method:

A 62-year- old female sustained a coronal shear fracture type IV of the distal part of left humerus that was primarily treated with open reduction and internal fixation using headless compression screws. Three years postoperatively, there was a migration of one screw into radiocapitellar joint that led to circular deep cartilage defect of radial head. Four years after ORIF, a distinctive radiocapitellar osteoarthritis has evolved leading to a resurfacing radiocapitellar joint replacement using the Lateral Resurfacing Elbow^TM (LRE) system.

Result:

At the 2-year follow-up after that procedure, there was an excellent subjective and functional outcome. Radiographically, no loosening or subsidence of implant without any signs of overstuffing could be found. The patient reported that she would have the same procedure again.

Conclusion:

The goal of unicompartmental radiocapitellar replacement is to obtain stability in elbow joint by avoiding cubitus valgus with subsequent instability of the distal radioulnar joint, and it does not alter the unaffected ulnohumeral joint. Additionally, the feature of the LRE^TM system is that the radial head is not excised, and so will receive the anatomical length of the overall radius articulating with the capitellum by preserving the annular ligament. In the literature only three publications could be found in which short-term results with the use of the LRE^TM system have been described. Hence, further studies are needed to validate this concept.

Intraoperative fluoroscopic assessment of proper prosthetic radial head height

BACKGROUND

Selecting a properly sized radial head prosthesis is imperative during radial head replacement. Although there has been much emphasis on avoiding overlengthening of the radius, little has been studied about how to avoid shortening. The purpose of this study was to characterize how a radial head replacement appears on intraoperative fluoroscopy depending on the height of the prosthetic radial head.

METHODS

Articular cartilage thickness of the radial head was measured in 9 cadaveric elbows. Radial head replacement was performed in each specimen with 4 different prosthetic head heights: 4 mm and 2 mm shortening, anatomic, and 2 mm overlengthening. Anteroposterior fluoroscopic images were obtained for each head height, and the prosthetic radial head height was measured at 3 forearm positions (supination, neutral, and pronation) using the subchondral bone of the lateral edge of the coronoid at the reference point.

RESULTS

The mean cartilage thickness of the radial head was 1.3 ± 0.4 mm. The prosthetic radial head appeared 2.2 ± 0.4 mm more proximal than the subchondral bone of the coronoid lateral edge in anteroposterior radiographs when the articular surface of the prosthesis was completely even with the coronoid articular surface. Unlike the native radial head, a prosthetic radial head showed a significant change of height with different forearm rotation (P < .001).

DISCUSSION

This study found that a perfectly anatomic radial head replacement appears overlengthened by approximately 2 mm in intraoperative radiographs. This finding can be useful in guiding the appropriate height of a prosthetic radial head.

[Primary radial head arthroplasty in trauma : Complications]

Radial head fractures are common injuries in elbow trauma. Non-displaced fractures are best treated conservatively. Simple but displaced fractures require anatomic reduction and fixation, typically using screws. The treatment course for complex fractures with multiple fragments is still being debated, as results are less predictable. Radial head resection is not advised if concomitant injuries of the coronoid process or the collateral ligaments with instability are present. Favorable outcomes following open reduction and fixation using plates were reported recently. However, complication rates are very high. Radial head replacement is a valuable tool in treating complex fractures of the radial head with predominantly good and excellent results. Patients who suffer radial head fractures are typically of a younger age, resulting in high functional demands. Certainly, unspecific and specific complications related to radial head arthroplasty were reported in up to 40 % of cases in an acute fracture setting. This article highlights common complications in radial head arthroplasty and aims to present strategies to avoid them.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

LEVEL OF EVIDENCE

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

Is the distal radioulnar variance useful for identification of radial head prosthesis overlengthening? A cadaver study

BACKGROUND

Overlengthening by radial head prosthetic replacement leads to insufficient functionality and increased capitellar wear. It has been shown that in monopolar prostheses, the radial overlengthening by an overstuffed prosthesis leads to significant differences in the distal radioulnar variance at the wrist. This study evaluated ipsilateral ulnar variance as a predictor for overlengthening after implantation of a multipolar prosthesis.

METHODS

The radial heads of seven fresh frozen upper extremities were resected and a multipolar radial head prosthesis was implanted. Thereafter, the native radioulnar variance at the wrist was documented via fluoroscopy. The alignment of the distal radioulnar joint in neutral, pronated and supinated rotational positions of the forearm was recorded fluoroscopically, and digital image analysis was performed regarding radioulnar shifting.

RESULTS

Statistical analysis of the difference between native height and the manipulated states did not show consistent significant differences with stepwise overlengthening of +1.5, +3, +4.5 and +6 mm and with respect to rotational position of the forearm (p > 0.05). Interclass correlation coefficients showed excellent interobserver reliability (ICC 96%), as did tests for intraobserver reliability (ICC 98-99%).

CONCLUSIONS

No consistent influence of overlengthening on the alignment of the radius and ulna at the distal radioulnar joint was found after sequential overlengthening with a multipolar prosthesis. Maybe the ligamentous structures of the forearm prevent significant longitudinal dislocation of the radius, as the multipolar prosthesis gives way by at the radiocapitellar joint. According to the data of the present study, the ipsilateral wrist is not useful in diagnosing overlengthening of the radial column in multipolar prosthetic replacement of the radial head-in contrast to the reported results with monopolar prostheses.

Terrible Triad Injuries of the Elbow

The treatment of terrible triad injuries of the elbow continues to evolve. Radial head fixation and arthroplasty, coronoid process fixation, and repair of the lateral collateral ligament continue to be the mainstays of treatment. In the elbow with persistent instability after repair of these elements, application of a static external fixation, hinged external fixation, ulnohumeral joint pinning, or an internal hinge may be needed. In patients who undergo treatment after the acute injury period, the coronoid may require reconstruction using radial head autograft, iliac crest autograft, olecranon autograft, or allograft.

Reliability of Magnetic Resonance Imaging Signs of Posterolateral Rotatory Instability of the Elbow

PURPOSE

To evaluate radiographic signs of posterolateral rotatory instability (PLRI) on magnetic resonance imaging (MRI). The goal was to establish objective radiographic criteria to aid in the diagnosis of PLRI.

METHODS

The MRI scans of 60 patients were evaluated retrospectively. Two study groups were compared. Group 1 (n = 30) consisted of unstable elbows in which PLRI was confirmed by clinical examination and arthroscopy. Group 2 (stable; n = 30) served as the control group. Patients in group 2 had transient epicondylitis without clinical suspicion of instability. Joint incongruity was analyzed for sagittal views through the radial head and the coronoid tip and for coronal and axial views. Interobserver and intra-observer reliability were evaluated.

RESULTS

In the sagittal view through the radial head, average radiocapitellar incongruity differed significantly between groups 1 and 2. In addition, mean ulnohumeral incongruity in an axial view through the motion axis of the distal humerus showed significant differences between groups. Sagittal views through the tip of the coronoid and coronal views did not reveal significant differences in patients with unstable elbows compared with the control group.

CONCLUSIONS

The current study provides useful MRI criteria indicative of PLRI when combined with physical examination. Cutoff points of 1.2 mm for radiocapitellar incongruity (sagittal view) and 0.7 mm for axial ulnohumeral incongruity (axial view) are suitable to screen for PLRI. Radiocapitellar incongruity greater than 2 mm and axial ulnohumeral incongruity greater than 1 mm are highly suspicious of elbow instability.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.

Management of complex elbow dislocations: a mechanistic approach

Complex elbow dislocations (ie, fracture-dislocations) are challenging injuries to treat and may result in significant patient morbidity. Chronic instability, posttraumatic arthrosis, and poor functional outcomes are frequent. Orthopaedic surgeons should strive to optimize elbow function through restoration of articular congruity and stability coupled with early rehabilitation. Although most of these injuries require surgical management, not all complex elbow dislocations are equivalent. Understanding elbow biomechanics and the injury mechanism provides valuable insight into the variations of pathology that may be observed. Identifying the particular fracture pattern, such as an axial loading, valgus posterolateral rotatory, or varus posteromedial rotatory injury mechanism, helps guide appropriate treatment.

Complications of radial head prostheses

Radial head prostheses are indicated for treatment of complex radial head fractures not amenable for fixation. After the initial experience with silastic implants, metallic or pyrocarbon arthroplasty have been used for 20 years. Little is known about complications related to these implants. Main complications are related to loosening whether they are cemented or not cemented. Hypotheses have been proposed like inadequate stem design, insufficient cement technique, stress shielding, and foreign body reactions secondary to polyethylene wear. Pain and stiffness are other common complications often related to oversized radial head component or overstuffing of the joint with excessive lengthening of the radius. Instability can be another complication in the context of more complex trauma with lateral collateral ligament complex lesion and coronoid fracture. Fixation of the coronoid fracture, reinsertion of the lateral collateral ligament complex, and the use of monobloc radial head prosthesis are recommended to stabilize the joint. Finally, osteoarthritis is common with follow-up.

Can ulnar variance be used to detect overstuffing after radial head arthroplasty?

BACKGROUND

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.

QUESTIONS/PURPOSES

We therefore hypothesized that overlengthening the radial head during radial head arthroplasty changes the ulnar variance in the wrist.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

CLINICAL RELEVANCE

The simplicity and reliability of ulnar variance make it a potentially useful indicator of overlengthening after radial head arthroplasty.

[Endoprosthetics of acute radial head fractures]

Radial head arthroplasty is the treatment of choice for non-reconstructble radial head fractures. Solid prostheses made of metal or pyocarbon can restore valgus stability of the elbow independent of design or stem fixation. Short-term and mid-term results show mostly good to excellent results without any evident differences between the different prosthesis philosophies. In order to obtain good results it is important to implant the prosthesis correctly without overfilling and to judge concomitant ligament injuries correctly. This article discusses the anatomical and biomechanical basis of radial head arthroplasty as well as the surgical technique and radiological diagnosis of overfilling.

Radial head fractures

Fractures of the radial head are the most common fractures in the elbow, and they frequently have associated ligamentous, cartilaginous, or other bony injuries. Clinical assessment and radiological investigation allow for accurate diagnosis and the formulation of a management plan. Undisplaced or minimally displaced fractures with no rotational block to motion can be treated nonoperatively with excellent results expected. The minimum amount of displacement in a partial articular radial head fracture required for open reduction and internal fixation to provide a superior outcome to nonoperative management is still unknown. Medium-term data suggest that patients with comminuted radial head fractures do well with radial head replacement.

Radial head replacement with unipolar and bipolar SBi system: a clinical and radiographic analysis after a 2-year mean follow-up

Radial head prosthetic replacement is indicated in case of comminuted fracture not amenable to internal fixation, especially when the radial head fracture is part of a pattern of lesions configuring a complex instability of the elbow. Thirty-one SBi radial head prostheses were implanted in 30 patients (one bilateral simultaneous fracture) over a 2 years period. In 10 patients, the mean time from trauma to surgical treatment was 2.4 days, while the remaining 20 patients were treated as "second opinion" cases presenting with elbow stiffness or instability after an average of 19 days from trauma. The implants were monopolar in 12 cases and bipolar in 19. The clinical results were evaluated through the Mayo Elbow performance scoring system. At an average follow-up of 2 years (range 13-36 months), the mean MEPS was 90 points (range 65-100). At late radiographic analysis, radiolucent lines around the stem were found in 11 of the 31 cases. Heterotopic ossifications were found in 14 cases. Bone resorption was observed in 9 cases. Two of the 31 prostheses were removed after 16 and 20 months, in one case to correct stiffness in pronation/supination, in the other one for asymptomatic aseptic mobilization. These short-term results are satisfactory, especially when considering that they were obtained in complex elbow lesions treated in many cases at a delayed stage. Our preference over time went more and more to bipolar implants, but from a comparison of the results we could find no evidence of a superiority of bipolar or monopolar implants. The evolution of these prostheses needs to be evaluated with further studies to assess mid-term and long-term follow-up results.

Contralateral elbow radiographs can reliably diagnose radial head implant overlengthening

BACKGROUND

Excessive lengthening of the radius with use of a radial head implant, a common cause of capitellar wear and clinical failure, is difficult to identify on radiographs of the injured elbow. The purpose of this study was to determine if a novel measurement technique based on radiographs of the contralateral elbow could be used to accurately estimate the magnitude of overlengthening due to the radial head implant. In part I of this study, we examined the side-to-side consistency of radiographic landmarks used in the measurement technique. In part II, the technique was validated in a cadaveric model with simulated radial head implant overlengthening.

METHODS

In part I of the study, a side-to-side comparison of elbow joint dimensions was performed with use of 100 radiographs from fifty patients. In part II, radial head prostheses of varying lengths (leading to 0, 2, 4, 6, and 8 mm of overlengthening) were implanted in four pairs of cadaveric specimens (eight elbows). Radiographic measurements were performed by two examiners blinded to the implant size to determine if radiographs of the contralateral elbow could be used to diagnose, and provide a valid estimate of the magnitude of, implant overlengthening. Intrarater and interrater reliability ratios, absolute measurement errors, and diagnostic accuracy were determined.

RESULTS

No significant side-to-side differences (p > 0.2) in radiographic measurements were identified between paired elbows. In the cadaveric model, the measurement technique involving use of radiographs of the contralateral elbow was successful in predicting the implant size (± 1 mm) in 104 (87%) of the 120 scenarios tested. The sensitivity of the technique--i.e., the ability of the test to correctly identify overlengthening (within ± 1 mm) when it was present--was 98%, with a positive likelihood ratio of 49 and a negative likelihood ratio of 0.02. The reliability of the radiographic measurements, based on repeated measurements performed by a single blinded orthopaedic surgeon on two separate occasions or based on separate measurements performed by two different orthopaedic surgeons, was excellent (intraclass correlation coefficient > 0.95).

CONCLUSIONS

A measurement technique based on radiographs of the contralateral elbow can be used to diagnose and calculate the magnitude of radial overlengthening due to the use of an incorrectly sized radial head implant.

Comminuted radial head fractures treated with pyrocarbon prosthetic replacement

PURPOSE

We had evaluated our experience in the treatment of displaced and comminuted radial head fractures with pyrocarbon radial head prosthesis.

METHODS

From May 2003 to July 2008, radial head prostheses were performed in 47 patients. There were 29 female and 18 male with mean age 51 (34-70 years). The follow-up was a mean of 48 (12-60 months). Fractures of the radial head have been classified by Hotchkiss. The indications for a radial head replacement were type III fractures in 27 cases, type IV fractures in ten cases, comminuted radial fracture associated with disruption of the medial collateral ligament in three cases, Monteggia variant in five cases, and Essex-Lopresti in two cases. Functional outcomes were assessed by visual analog scales (VAS) of pain, joint motion and stability, and using the Mayo Elbow Performance Index.

RESULTS

The mean VAS score for elbow pain was 1 (0.5-2.1). Patients showed an average arc of motion from 6° to 140°, with 75° of pronation and 67° of supination. By using the Mayo Elbow Performance Index, 42 patients had good/excellent results, with three fair and two poor outcomes. Complications were two implant dislocations, one elbow stiffness, one dissociation of the implant, one stem rupture, and two posterior interosseous nerve palsy that recovered from 5 to 8 weeks. We had not seen persistent instability, infection, synostosis, severe degenerative changes, or impingement.

CONCLUSIONS

The treatment of comminuted radial head fracture with pyrocarbon implant usually gives an optimal result depending on the severity of the initial injury and the presence of associated lesions. The size of the prosthesis is often overestimated, causing restriction in motion due to impingement, overstuffing, or dislocations.

Simple overlay device for determining radial head and neck height

BACKGROUND

The purpose of this study was to test the hypothesis that a simple overlay device can be used on radiographs to measure radial head and neck height.

MATERIALS AND METHODS

Thirty anteroposterior elbow radiographs from 30 patients with a clinical diagnosis of lateral epicondylitis were examined to measure radial head and neck height. Three methods using different points along the bicipital tuberosity as a landmark were used. Method 1 used the proximal end of the bicipital tuberosity, method 2 used the most prominent point of the bicipital tuberosity, and method 3 used a simple overlay device (SOD) template that was aligned with anatomic reference points. All measurements were performed three times by three observers to determine interobserver and intraobserver reliability.

RESULTS

Intraclass correlation coefficients revealed higher interobserver and intraobserver correlations for the SOD template method than for the other two methods. The 95% limits of agreement between observers were markedly better (-1.8 mm to +1.0 mm) for the SOD template method than for the proximal point method (-3.8 mm to +3.4 mm) or the prominent point method (-5.9 mm to +4.9 mm).

CONCLUSIONS

We found that the SOD template method was reliable for assessing radial head and neck height. It had less variability than other methods, its 95% limit of agreement being less than 2 mm. This method could be helpful for assessing whether or not the insertion of a radial head prosthesis has resulted in over-lengthening of the radius.

Determination of correct implant size in radial head arthroplasty to avoid overlengthening: surgical technique

BACKGROUND

Insertion of a radial head implant that results in radial overlengthening has been associated with altered elbow kinematics, increased radiocapitellar joint forces, capitellar erosions, early-onset arthritis, and loss of elbow flexion. The purpose of this study was to identify clinical and radiographic features that may be used to diagnose overlengthening of the radius intraoperatively and on postoperative radiographs.

METHODS

Radial head implants of varying thicknesses were inserted into seven cadaver specimens, which were then assessed clinically and radiographically. Eight stages were examined: the intact specimen (stage 1); repair of the lateral collateral ligament (stage 2); radial head resection with repair of the lateral collateral ligament (stage 3); insertion of an implant of the correct thickness (stage 4); and insertion of an implant that resulted in radial overlengthening of 2 mm (stage 5), 4 mm (stage 6), 6 mm (stage 7), or 8 mm (stage 8). The specimens were tested with and without muscle loading to simulate resting muscle tone and surgical paralysis, respectively. At each stage, radiographs were made to measure the ulnohumeral joint space and the lateral ulnohumeral joint was visually assessed.

RESULTS

We identified no difference, with regard to medial ulnohumeral joint incongruity as seen radiographically, among stages 1 through 6 during the tests with muscle loading. A significant difference in medial ulnohumeral joint incongruity was found in stages 7 (p = 0.003) and 8 (p < 0.001). The clinical (visually assessed) lateral ulnohumeral joint space gap was negligible in stages 1 through 4 but increased significantly at all stages involving overlengthening (gross gap, 0.9 mm with 2 mm of erlengthening [p = 0.005], 2.3 mm with 4 mm of overlengthening [p < 0.001], 3.4 mm with 6 mm [p < 0.001], and 4.7 mm with 8 mm [p < 0.001]).

CONCLUSIONS

Incongruity of the medial ulnohumeral joint becomes apparent radiographically only after overlengthening of the radius by ≥6 mm. Intraoperative visualization of a gap in the lateral ulnohumeral joint is a reliable indicator of overlengthening following the insertion of a radial head prosthesis.

Failure of metal radial head replacement

There is little information available at present regarding the mechanisms of failure of modern metallic radial head implants. Between 1998 and 2008, 44 consecutive patients (47 elbows) underwent removal of a failed metallic radial head replacement. In 13 patients (13 elbows) the initial operation had been undertaken within one week of a fracture of the radial head, at one to six weeks in seven patients (seven elbows) and more than six weeks (mean of 2.5 years (2 to 65 months)) in 22 patients (25 elbows). In the remaining two elbows the replacement was inserted for non-traumatic reasons. The most common indication for further surgery was painful loosening (31 elbows). Revision was undertaken for stiffness in 18 elbows, instability in nine, and deep infection in two. There were signs of over-lengthening of the radius in 11 elbows. Degenerative changes were found in all but one. Only three loose implants had been fixed with cement. Instability was not identified in any of the bipolar implants.

Determination of correct implant size in radial head arthroplasty to avoid overlengthening

BACKGROUND

Insertion of a radial head implant that results in radial overlengthening has been associated with altered elbow kinematics, increased radiocapitellar joint forces, capitellar erosions, early-onset arthritis, and loss of elbow flexion. The purpose of this study was to identify clinical and radiographic features that may be used to diagnose overlengthening of the radius intraoperatively and on postoperative radiographs.

METHODS

Radial head implants of varying thicknesses were inserted into seven cadaver specimens, which were then assessed clinically and radiographically. Eight stages were examined: the intact specimen (stage 1); repair of the lateral collateral ligament (stage 2); radial head resection with repair of the lateral collateral ligament (stage 3); insertion of an implant of the correct thickness (stage 4); and insertion of an implant that resulted in radial overlengthening of 2 mm (stage 5), 4 mm (stage 6), 6 mm (stage 7), or 8 mm (stage 8). The specimens were tested with and without muscle loading to simulate resting muscle tone and surgical paralysis, respectively. At each stage, radiographs were made to measure the ulnohumeral joint space and the lateral ulnohumeral joint was visually assessed.

RESULTS

We identified no difference, with regard to medial ulnohumeral joint incongruity as seen radiographically, among stages 1 through 6 during the tests with muscle loading. A significant difference in medial ulnohumeral joint incongruity was found in stages 7 (p = 0.003) and 8 (p < 0.001). The clinical (visually assessed) lateral ulnohumeral joint space gap was negligible in stages 1 through 4 but increased significantly at all stages involving overlengthening (gross gap, 0.9 mm with 2 mm of overlengthening [p = 0.005], 2.3 mm with 4 mm of overlengthening [p < 0.001], 3.4 mm with 6 mm [p < 0.001], and 4.7 mm with 8 mm [p < 0.001]).

CONCLUSIONS

Incongruity of the medial ulnohumeral joint becomes apparent radiographically only after overlengthening of the radius by >or=6 mm. Intraoperative visualization of a gap in the lateral ulnohumeral joint is a reliable indicator of overlengthening following the insertion of a radial head prosthesis.

Radial head implant arthroplasty

Radial head arthroplasty has developed into a reliable procedure to address fractures of the radial head not amenable to reconstruction, particularly when associated with an unstable elbow or forearm. Good to excellent results can be anticipated when used for the correct indications and when care is taken to understand and address the concomitant injuries. This article will discuss the technique of radial head arthroplasty in the context of the injuries that often accompany radial head fractures.

Plain radiographs are inadequate to identify overlengthening with a radial head prosthesis

PURPOSE

A correctly sized radial head implant helps restore more normal elbow motion and load distribution and allows the collateral ligaments to heal in an anatomic position. No single method of measurement has been agreed on. We hypothesized that plain radiographs could be used to evaluate the appropriate length of a radial head prosthesis when we simulated different patterns of ligament disruption.

METHODS

Osteotomies of the medial and lateral condyles were created in 6 cadaver specimens to simulate 4 conditions: ulnar collateral ligament (UCL) and lateral ulnar collateral ligament (LUCL) intact, UCL intact, LUCL intact, and UCL and LUCL disrupted. Radial heads were resected and replaced with correctly or incorrectly sized monopolar radial head implants. Radiographs were taken after simulated ligament injury with a radial head prosthesis that was either 2 mm too short, the appropriate length, or too long by either 2 or 4 mm. Measurements were recorded between radiographic markers to determine ulnohumeral joint displacement. A 4 x 4 x 2 repeated-measures analysis of variance was performed, as well as post hoc analyses using Tukey's honest significant difference test, to determine statistically significant changes in our radiographic measurements.

RESULTS

Results showed that disruption of at least 1 ligament alters the ulnohumeral joint separation on the lateral but not on the anteroposterior radiograph. Overlengthening the radial head did not result in a statistically significant change in ulnohumeral space.

CONCLUSIONS

Replicating radial length is an important but sometimes difficult step during radial head replacement. Standard radiographic assessment of the ulnohumeral joint will not demonstrate marked changes in the ulnohumeral space when the implant is underlengthened by 2 mm or overlengthened by as much as 4 mm, as long as the joint remains located. Disruption of at least 1 collateral ligament alters the ulnohumeral joint separation on the lateral but not on the anteroposterior radiograph.