Radial head arthroplasty: a historical perspective

Intelligent anatomic design of porous radial head prosthesis and microscopic-macro biomechanical finite element analysis in the long-term after replacement surgery

BACKGROUND

The microporous structure of porous titanium alloy may affect osteoblast differentiation and reduce effective elastic modulus (EEM) of the prostheses. Therefore, the biomechanics-based anatomic design of porous radial head prosthesis (PRHP) may help promote bone healing and reduce postoperative complications.

METHODS

A microscopic-macro virtual testing platform (VTP) was built to design cells with excellent mechanical properties, further, to construct the PRHP. An intelligent anatomic platform of healthy human elbow-forearms was developed to construct finite element (FE) models of solid radial head prosthesis (SRHP) and PRHP replacement for Mason type III fractures. Axial and valgus loads were applied for surgical model validation and microscopic-macro biomechanical analysis.

RESULTS

The order of ultimate compressive load (UCL) and yield strength (YS) of five types of cells is NEWTET>KAGOME>NEWPYRAMID>TET>PYRAMID. Under the same porosity conditions, UCL and YS of the double and four-layer lattice structures of NEWTET decreased by 62.39%, 69.46% and 61.70%, 70.21% compared to the single-layer, respectively. The EEM of NEWTET-based PRHP is 17.66% of that of SRHP. Compared with the SRHP replacement, PRHP replacement reduced the humeral cartilage stress by 18.96%-19.51%.

CONCLUSIONS

NEWTET cell has better microscopic mechanical properties and bone-growth adaptability. The EEM of NEWTET-based PRHP closely resembles cortical bone. Compared with SRHP replacement, microscopic-macro biomechanical performance in long-term after PRHP replacement is closer to that of a normal elbow joint. The microscopic-macro VTP and human intelligent anatomic elbow-forearm FE analysis systems provide efficient, accurate, and smart tools for the design of porous prostheses in joint replacement surgery.

Three-Dimensional Orientation of the Radial Neck Axis Angulation: Implications for Radial Head Replacement

PURPOSE

The purpose of this study was to determine the 3-dimensional (3D) orientation of the radial neck axis with respect to the forearm rotation axis and explore its theoretical implications for radial head prosthetic replacement.

METHODS

Computed tomography scans of the forearm of healthy individuals were used to construct 3D bone models defining the relationship between the forearm rotation and radial neck axes (FRANA). These models were adjusted to achieve neutral forearm rotation. A comprehensive method for measuring FRANA in 3D was developed, and the results were compared with those of clinical simulated 2-dimensional (2D) projections.

RESULTS

In 20 patients, the 3D FRANA angle averaged 5.1° (SD: 2.2°, 95% confidence intervals [CI]: 4.1-6.2°) consistently oriented toward the palmar side. This was strongly correlated (r = 0.87) with 2D measurements in the anterior view with the forearm in neutral rotation (mean: 4.5°, SD: 2.3°, 95% CI: 3.5°-5.6°), but not with the measurements in the lateral view (mean: -0.1°, SD: 2.5°, 95% CI: -1.3° to 1.0°). Angular measurements in the anterior view were strong predictors of 3D FRANA (R2 = 0.8).

CONCLUSIONS

The axis of the radial neck does not line up precisely with the axis of forearm rotation but points to a location that is approximately 2 cm palmar to the fovea of the distal ulna. Significant differences were found between 3D and 2D lateral measurements, which highlights the benefits of computer-assisted modeling for analyzing proximal radial geometry.

CLINICAL RELEVANCE

With the forearm in neutral rotation, the proximal radial canal is aligned with the axis of forearm rotation in the sagittal plane but points to a mean of 5° palmarly in the coronal plane. This information can be used to optimize the radial neck cut and direction of canal preparation prior to prosthesis insertion.

Short- to midterm outcomes of 139 pyrocarbon monopolar radial head arthroplasties

BACKGROUND

The MoPyc radial head arthroplasty (RHA) is a monopolar implant with a pyrocarbon head that obtains rigid fixation via controlled expansion of the titanium stem. The aim of this study was to evaluate the short-term to midterm outcomes of MoPyc RHA.

MATERIALS AND METHODS

Between 2002 and 2021, 139 MoPyc RHA were implanted in 139 patients with a RH fracture. The mean follow-up was 5.9 years ± 3.5 (range 1-16). Range of motion, mean Mayo Elbow Performance Score (MEPS), Quick Disabilities of the Arm, Shoulder and Hand score, visual analog scale (VAS), radiographic outcome, and reason for failure were recorded.

RESULTS

The mean MEP, Quick Disabilities of the Arm, Shoulder and Hand, and VAS scores were 89.1 ± 2.2 (range, 45-100), 17.5 ± 16.7 (range, 0-78), and 0.8 ± 1.6 (range, 0-50), respectively. Stress shielding (SS) and osteolysis around the stem were identified in 92 (66%) and 20 (14%) patients. A total of 47 (29%) patients experienced at least 1 complication and 29 (21%) of them required re-intervention. Persistent stiffness (n = 12; 9%) was the most common complication. No painful loosening was noted. Osteolysis around the stem, presence of an autoexpanding stem, and overstuffing were associated with a lower MEPS and an increase in VAS (P < .05). SS was associated with an increase in MEPS (adjusted beta coefficients= 6.92; P < .001) and lower VAS (adjusted beta coefficients= -0.69; P = .016). The autoexpending stem increased the likelihood of SS after RHA (adjusted odds ratio = 1.49; P = .001).

CONCLUSIONS

A well-fixed MoPyc RHA provided satisfactory short to midterm outcomes, without painful loosening. However, the autoexpanding stem system was associated with poorer functional outcomes and increased the likelihood of SS.

Revision radiocapitellar arthroplasty by mismatched implant components - A salvage option: A report of two cases with a minimum three-year follow-up

Radiocapitellar arthroplasty has been shown to improve pain and function in patients with a degenerative joint. Due to problems with the loosening of the radial head component, one of the few available systems was removed from the global market. This offered specific challenges in terms of treatment strategies when one or both components of a system that is no longer available fail. Due to the very different geometry of the capitellar implant, revision of the capitellar component would require a complex procedure, likely requiring bone graft and a high chance of early failure, leaving resection or interposition arthroplasty as the only available option. Although implant mismatch is common practice in hip and knee arthroplasty with satisfactory results, it should remain a salvage option as the off-label use of components gives rise to several medicolegal implications. We report two cases of radiocapitellar arthroplasty partial revision, by replacing only the radial head component with an implant from another system while keeping the well-fixed original capitellar component in place. At a minimum of three-year follow-up, both cases improved from poor to good and excellent Mayo elbow performance scores. There were no signs of implant failure on standard radiographs.

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

PURPOSE OF THE STUDY

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

KEY WORDS

radial head, elbow, fracture, dislocation, resection, prosthesis.

Radial head replacement for acute complex elbow instability: a long-term comparative cohort study of 2 implant designs

BACKGROUND

Radial head fractures not amenable to reconstruction should be treated by radial head replacement (RHR) when there is associated elbow or forearm instability. There are multiple RHR designs with different philosophies, but 2 of the most commonly used implants include the anatomic press-fit radial head system and the loose-fit metallic spacer. There is little information available specifically comparing the long-term clinical and radiographic outcomes of these 2 systems. The objective of this study was to compare the long-term clinical and radiologic outcomes of 2 RHR designs in the context of complex acute elbow instability.

MATERIALS AND METHODS

Ninety-five patients with an average age of 54 years (range, 21-87 years) underwent an acute RHR (46 press-fit Acumed anatomic and 49 loose-fit Evolve metallic spacer) and were prospectively followed for an average of 61 months (range, 24-157 months). There were 34 terrible triads; 36 isolated RH fractures with medial, lateral, or longitudinal instability; and 25 RH fractures associated with a proximal ulnar fracture. Clinical outcome and disability were evaluated with the Mayo Elbow Performance Score (MEPS), the Oxford Elbow Score, and the Disabilities of the Arm, Shoulder, and Hand (DASH) score. Pain and satisfaction were assessed using a visual analog scale. Radiographic analysis included presence of loosening, bone loss, and overstuffing related to the RHR.

RESULTS

Eight patients with an anatomic RHR (2 with overstuffing, 3 for stiffness, and 3 with loose implants) and 1 patient with a spacer (with stiffness) required implant removal. There were no significant differences between spacer RHR and anatomic RHR in arc of motion (120° vs. 113°, P = .14), pain relief (1 vs. 1.7, P = .135), MEPS (94 vs. 88; P = .07), Oxford Elbow Score (42.3 vs. 42.2, P = .4), or DASH score (12.2 vs. 14.4, P = .5). However, patients with a spacer RHR were significantly more satisfied (9 vs. 7.7; P = .004) than those with an anatomic implant. Radiographically, 19 anatomic implants had significant proximal bone loss and 10 showed complete lucent lines around the stem. Lucent lines were common around the spacer RHR. These radiographic changes were not always related to worse clinical outcomes.

CONCLUSION

Both the anatomic and spacer RHR designs can provide good clinical long-term outcomes. However, patients with a spacer showed a higher degree of satisfaction and those with an anatomic press-fit RHR had a higher revision rate, with radiographic changes that warrant continued follow-up.

90-day outcomes and factors for complications following radial head arthroplasty for Mason Type III and IV radial head fractures

PURPOSE

The aim of this study is to evaluate 90-day outcomes and complications following radial head arthroplasty (RHA) for Mason Type III and IV radial head fractures (RHFs) and determine factors predisposing patients to early complications and revision surgery.

METHODS

Patients undergoing RHA for Mason Type III and IV RHFs were identified retrospectively from an institutional database. Postoperative complications, reoperations, elbow range of motion, radiographs and concomitant injuries on the ipsilateral upper extremity were reviewed. Additionally, injuries were sub-classified as low-energy trauma (LET) or high-energy trauma (HET). Univariate logistic regression was performed to evaluate the risk for complications using patient factors not limited to the presence of concomitant ligamentous or bony injuries. P values < 0.05 were considered statistically significant.

RESULTS

Seventy four patients were included in our study with an average follow-up time of 12.7 months. Complications within 90-days of operation occurred in 8.1% of patients: heterotopic ossification (4.1%), superficial wound dehiscence (2.7%), and posterior interosseous nerve palsy (1.4%). No patients required readmission or revision surgery in the 90-day postoperative period. Univariate regression analysis did not demonstrate a significant association between diabetes, ASA status, HET versus LET, or the presence of concomitant injury. Concomitant injuries were found in 92% of patients.

CONCLUSION

Radial head arthroplasty for RHFs demonstrates a low complication rate in the short-term. Diabetes, ASA class, high versus low energy trauma, and presence of concomitant injury were not found to be associated with higher complication rates in the 90-day postoperative period.

LEVEL OF EVIDENCE

Level of evidence IV, retrospective case series.

Silicone radial head prostheses revisited: do they have a role in today's practice? A systematic review of literature on clinical outcomes

BACKGROUND

Silicone radial head prostheses (SRHP) are considered obsolete due to reports of frequent failure and destructive silicone-induced synovitis. Considering the good outcomes of modern non-radial silicone joint implants, the extent of scientific evidence for this negative view is unclear. The aim of this research was to systematically analyze the clinical evidence on complications and outcomes of SRHP and how SRHP compare to both non-SRHP and silicone prostheses of other joints.

METHODS

A systematic literature review was conducted through the Cochrane, PubMed, and Embase databases.

RESULTS

Eight cohort studies were included, consisting of 142 patients and follow-up periods ranging from 23 months to 8 years. Average patient satisfaction was 86%, range of 71%-100%, and 58 complications were seen, but no cases of synovitis. These outcomes were in line with non-SRHP. Four case series with 11 cases of synovitis were found, all due to implant fractures years to decades after implantation. Six systematic reviews of currently used non-radial silicone joint implants showed excellent outcomes with low complication rates.

CONCLUSIONS

Since SRHP have satisfactory clinical results and an acceptable complication rate when selecting a patient group in suitable condition for surgical indications, it is considered that SRHP can still be chosen as a potential surgical treatment method in current clinical practice.

Efficacy and safety of monopolar versus bipolar radial head arthroplasty: a systematic review and meta-analysis

BACKGROUND

Radial head replacement is the main line of treating complex unstable elbow injuries. Radial head prostheses are either monopolar or bipolar. The difference between both designs in patients' clinical outcomes and postoperative complications is not yet clear. So, a systematic review and meta-analysis was conducted to evaluate the efficacy and safety of monopolar vs. bipolar implants.

MATERIALS AND METHODS

PubMed, EMBASE, Cochrane, and Scopus were searched to identify studies comparing monopolar and bipolar implants. Data on clinical outcomes, postoperative complications, revision, and removal rates were extracted.

RESULTS

Nine studies met our inclusion criteria, with a total of 591 patients (365 monopolar and 226 bipolar). Both prostheses achieved similar ranges of motion; Mayo Elbow Performance Score; Disabilities of the Arm, Shoulder, and Hand score; and visual analog scale for pain. Incidence of postoperative complications was also similar between both designs. Revision and removal rates were 24%, 8% and 29%, 14% for monopolar and bipolar implants, respectively, but no statistically significant difference could be detected.

CONCLUSIONS

No significant difference was found between monopolar and bipolar radial head prostheses in terms of efficacy and safety. Therefore, high-quality randomized controlled trials are required to determine the superiority of one design over the other.

A registry study on radial head arthroplasties in the Netherlands: Indications, types and short-term survival

BACKGROUND

This study aims to use the Dutch Arthroplasty Register data to report an overview of the contemporary indications and implant designs, and report the short-term survival of radial head arthroplasty.

METHODS

From the Dutch Arthroplasty Register, data on patient demographics, surgery and revision were extracted for radial head arthroplasties performed from January 2014 to December 2019. Implant survival was calculated using the Kaplan-Meier method.

RESULTS

Two hundred fifty-eight arthroplasties were included with a median follow-up of 2.2 years. The most common indication was a fracture of the radial head (178, 69%). One hundred thirty-nine (68%) of the prostheses were of bipolar design, and the most commonly used implant type was the Radial Head System (Tornier; 134, 51%). Of the 258 included radial head arthroplasties, 16 were revised at a median of six months after surgery. Reason for revision was predominantly aseptic loosening (9). The overall implant survival was 95.8% after one year, 90.5% after three years and 89.5% after five years.

DISCUSSION

For radial head arthroplasties, acute trauma is the most common indication and Radial Head System the most commonly used implant. The implant survival is 89.5% after five years.

Long-Term Outcomes of Radial Head Arthroplasty in Complex Elbow Fracture Dislocation

The purpose of the current study was to investigate the long-term outcomes of radial head arthroplasty in complex elbow injuries through radiographic analysis and functional correlation. We evaluated 24 radial head arthroplasties in 24 consecutive patients with complex elbow fracture dislocation. All patients were treated with a single type of modular monopolar prosthesis containing smooth stem in press-fit implantation. Clinical survey using the Mayo Elbow Performance Score (MEPS), self-reported scales of shortened Disabilities of the Arm, Shoulder, and Hand (QuickDASH) and the visual analog scale (VAS) at more than 10-year follow-up were reported and compared to 2-year outcomes. Periprosthetic osteolysis was measured in the 10 zones of prosthesis-cortical interface with a modified radiolucency score, which was calibrated by each prosthesis size. Pearson correlation analysis was performed to detect the association between periprosthetic radiolucency and clinical assessment. At the final follow-up, MEPS, QuickDASH score and VAS score averaged 82.5 ± 15, 14.1 ± 14.3 and 1.6 ± 1.2 respectively. A decline in functional status was noted, with decreased mean MEPS and increased mean QuickDASH and VAS scores as compared to the 2-year results while the difference was insignificant. Periprosthetic osteolysis was more prevalent around stem tip of zone 3 and zone 8. The final and 2-year radiolucency scores averaged 7.4 ± 4.2 and 2.6 ± 2.3 respectively with significant difference. Pearson correlation analysis indicated that the difference between radiolucency scores and clinical outcomes in MEPS/QuickDASH/VAS was -0.836, 0.517 and 0.464. Progression of periprosthetic osteolysis after postoperative 10 years is more prevalent around the stem tip with moderate to high correlation to clinical outcomes. Sustained follow-up is warranted to justify subsequent surgery for revision or implant removal.

Outcomes of press-fit radial head arthroplasty following complex radial head fractures

INTRODUCTION

Press-fit radial head arthroplasty (RHA) is increasingly popular in treating complex radial head fractures. This study assessed the outcome of RHA, including the outcome following re-operation, and explored potentially influencing factors.

HYPOTHESIS

Complex radial head fractures treated with press-fit radial head prosthesis would have a favourable outcome.

MATERIAL AND METHODS

Data on all consecutive patients treated with anatomic press-fit RHA from February 2002 to February 2015 were analysed. Post-surgery clinical and X-rays assessments included a post-discharge evaluation of function. Standardised methods implemented include the assessment of range of motion (ROM), the Mayo Elbow Performance Score (MEPS) and subjective satisfaction scales.

RESULTS

Forty-five patients were recruited and 71% were classified in Mason IV and 62.2% had the "terrible triad". Re-operation was performed in 26.7% and prosthesis removal in 15.6%. Mean follow-up was 140.8 months (95% CI 117.7-164) and prosthesis survival was 69.5% at 24 months. Mean MEPS before re-operations was 86.3±15.9. Pain and/or instability were the most common reasons for re-operation, and re-operations were significantly more frequent in patients having one or more "associated injuries" (p=0.05), but not the terrible triad; and in patients with radiological "loosening" signs (p<0.01). Subjective scores were relatively good in most patients, although the functionality perceived in the re-operation with implant removal group was rather low.

DISCUSSION

Several studies of complex radial head fractures treated with press-fit radial head prosthesis have also shown favourable results, but the patients in such studies generally had less severe lesions. Moreover, differently from previous reports, this study with a long follow-up has included a younger population with high functionality requirements. Pain and/or instability, as observed in several previous reports, were the most common reasons for re-operation, but contrary to the expectation, the terrible triad was not associated with unfavourable outcome.

CONCLUSION

Treatment of complex fractures with press-fit radial head prosthesis, including re-operation with implant removal yields satisfactory results. Most scores of functional and subjective outcome improved following the re-intervention and most patients returned to their usual occupation.

LEVEL OF EVIDENCE

Level IV; case series; treatment study.

Post-traumatic elbow osteoarthritis after radial head arthroplasty: Prevalence and risk factors

BACKGROUND

One of the treatment options for comminuted radial head fractures is radial head arthroplasty (RHA), especially when the elbow is also dislocated. While the clinical outcomes of RHA have been well documented, the incidence of post-traumatic osteoarthritis after RHA and its risk factors are not well known.

OBJECTIVE

To determine the incidence of post-traumatic elbow osteoarthritis (humeroulnar and humeroradial joints) after RHA and identify its risk factors.

METHODS

All patients who underwent RHA at our hospital between 2008 and 2016 were included retrospectively. The inclusion criteria were primary RHA, recent radial head fracture (isolated or associated with elbow dislocation), minimum 1 year of follow-up, clinical and radiographic examination at final assessment. The exclusion criteria were pre-existing elbow osteoarthritis, RHA revision, multiple fractures of the ipsilateral upper limb or polytrauma. The final assessment consisted of a clinical examination [joint range of motion (ROM) and Mayo Elbow Performance Score (MEPS)] and standard radiographs. The correlation between the incidence and severity of osteoarthritis and various risk factors was determined.

RESULTS

Seventy-three patients were included in the analysis with a mean age of 56 years (21-85). The injuries consisted of 41 terrible triad, 15 isolated radial head fractures, 11 Monteggia fractures and 6 transolecranon fracture-dislocations. The mean follow-up was 3.4 years (1-10.9). At the final assessment, osteoarthritis was visible in the humeroulnar compartment in 56% of cases and in the humeroradial compartment in 72% of cases. There was a statistical correlation between the presence of humeroulnar osteoarthritis at the final assessment and ROM in flexion-extension (p=0.003), MEPS (p<0.001), duration of immobilization (p=0.03) and presence of posterior subluxation on immediate postoperative radiographs (p=0.012). The correlation between humeroradial osteoarthritis at the final assessment and ROM in flexion-extension (p=0.0054), RHA implant position (p<0.01), and unipolar configuration (p=0.027) was statistically significant.

CONCLUSION

In our study, elbow osteoarthritis incidence after RHA was 56% in the humeroulnar joint and 72% in the humeroradial joint. RHA implant placement, posterior subluxation immediately postoperative and the duration of immobilization were significantly corelated with osteoarthritis.

LEVEL OF EVIDENCE

IV; case series without control group.

Retrospective cohort study on radial head arthroplasty comparing long-term outcomes between valgus type injury and fracture dislocation

BACKGROUND

Radial head arthroplasty (RHA) has been commonly adopted for irreparable radial head fractures while little information is addressed on valgus type injury. The purpose of this study is to report long-term outcomes and radiographic analysis in RHA for valgus type injury with comparison to fracture dislocation injury.

METHODS

A retrospective cohort study was conducted in patients receiving unilateral RHA with loose-fit, modular metal prosthesis for irreparable radial head fractures between 2004 and 2012. Totally, 33 patients with a mean follow up of 9 years (range, 7 to 15 years) were enrolled and divided into two groups including 14 valgus injuries and 19 fracture-dislocations. Demographics of the patients, injury details, clinical and radiographic outcomes, and correlation analysis were investigated and compared between two groups.

RESULTS

In patient demographics, significant difference was noted in sex distribution (p = 0.001), lateral collateral ligament involvement (p = 0.000) and time from injury to RHA (p = 0.031) between two groups. No patient underwent subsequent removal or revision of prosthesis. Good to excellent results according to Mayo Elbow Performance Score (MEPS) was achieved in 13 and 14 patients in group A and B respectively. Final motion range and Disabilities of the Arm, Shoulder, and Hand score was significantly better in valgus injury group. Radiographic analysis demonstrated fewer patients in valgus injury group presented periprosthetic osteolysis with weak to moderate negative correlation between radiolucency score and MEPS.

CONCLUSIONS

With an average of 9 years follow-up, RHA using loose-fit, modular metal prosthesis achieves encouraging outcomes for both valgus injury and fracture dislocation. In valgus type injury, better motion range, lower disability score and lower incidence of periprosthetic osteolysis is noted while correlation analysis of radiolucency score suggests extended, long-term investigation.

Reliability of dynamic fluoroscopy for medial elbow stability in the presence of radial head resection

Background

The aim of this study was to examine whether dynamic fluoroscopy is reliable for assessment of medial elbow stability in the presence of radial head resection and different stages of medial collateral ligament (MCL) dissection in a cadaveric elbow model.

Materials and methods

Six intact elbow specimens were measured for joint angulation while applying valgus stress in four examination conditions (Examiner 1, Examiner 2, 1 Nm, 2 Nm) in four different elbow positions (fully pronated or supinated at 0° of elbow extension and 30° of elbow flexion). The elbow specimens were examined for valgus stress in three stages: (1) intact, (2) after radial head resection, and (3) after subsequent dissection of the complete MCL. Anteroposterior radiographs of the elbow were made at each stage to determine joint angulation. Intraclass correlation coefficients (ICCs) were calculated.

Results

In intact elbows, mean joint angulation ranged from 2.2° ± 2.0 (1 Nm) to 5.2° ± 2.3 (Examiner 1). Radial head resection did not increase joint angulation during valgus stress, regardless of joint position and examination condition (Examiner 1: 5.5°; Examiner 2: 5.0°; 1 Nm: 2.6°, 2 Nm: 3.9°). Additional dissection of the MCL led to significantly higher joint angulation during measurements with the standardized torques (1 Nm: 12.4°; 2 Nm: 23.3°). Very good to excellent ICCs for joint angulation between Examiner 1 and Examiner 2 (0.861 to 0.959) were found.

Conclusion

Dynamic fluoroscopy is a reliable diagnostic tool for determining medial elbow stability in the presence of radial head resection and different stages of MCL dissection.