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

Long-term outcomes of a cemented bipolar radial head prosthesis: a large retrospective study

BACKGROUND

In acute radial head fractures (RHFs), a radial head prosthesis can be considered if open reduction and internal fixation are not technically feasible. This study provides the largest long-term clinical and radiologic follow-up study of cemented bipolar Judet prostheses implanted to manage acute RHFs, either isolated and associated with other elbow fractures. We compare their functional and radiographic outcomes to test the hypothesis that the bipolar design can achieve similar results in both groups.

METHODS

We reviewed data of 63 consecutive patients implanted with a bipolar prosthesis (the articulation between the stem and the cup is semiconstrained and gives the radial cup a double range of movement) to treat unreconstructable RHFs with/without other fractures. Fifty-two patients had more than 10-year follow-up. Assessments included range of motion and stability using the Mayo Elbow Performance Score and the QuickDash questionnaire score, pain with a visual analog scale, and overall satisfaction with an interview. X-rays were examined to check the correct seating of the implant and periprosthetic loosening, prosthetic disassembly, heterotopic ossification, and capitellum and ulnohumeral degenerative changes.

RESULTS

At a mean follow-up of 150 months, 90% of patients were satisfied, with a mean Mayo Elbow Performance Score of 89 (range, 70-100) and a mean QuickDash score of 6.8 (range, 0-18.2). The mean arc of motion was 113° (range, 70°-140°) in flexion-extension and 149° (range, 100°-160°) in pronation-supination. Nineteen patients (30%) patients required reoperation in the first 3 years.

CONCLUSIONS

The bipolar Judet prosthesis is a viable implant for acute irreducible RHFs. Clinical and radiologic outcomes and complications leading to reoperation were not significantly different between isolated radial head fractures and associated radial head fractures patients.

Plate or Arthroplasty for complex Mason Type-III Radial Head Fractures? Mid-to-long term results from a blinded outcome assessor study

BACKGROUND

The surgical treatment of radial head fractures like Mason type III comminuted radial head fractures is challenging and controversial. Whether to use open reduction and internal fixation (ORIF) or radial head arthroplasty (RHA) as treatment methods is under constant debate.

METHODS

We retrospectively analyzed clinical and radiographic mid- to long-term results of 42 patients with a mean follow-up time of 4.56 years (1.92-7.58 years). Patients were grouped according to fragment numbers and the type of intervention performed (3-4 fragments vs. 4+ fragments; ORIF vs. RHA). At the final follow-up, range of motion (ROM), functional rating scores and subjective pain and function levels were documented by a blinded outcome assessor.

RESULTS

Although minor differences in the mean values were detected when comparing the results of the functional scores, ROM and subjective pain and function levels, only the movement in pronation and supination direction yielded statistically better results in the group of 4+-fragments for the RHA compared to ORIF. However, the 33 % rate of required implant removal amongst the ORIF group should be considered.

CONCLUSIONS

This study provides evidence that 3- and 4-part Mason type III fractures are prone to plate osteosynthesis. In contrast, greater than 4-part fractures can more reliably be treated by replacement. This leads to a proposed increase in fragment numbers to four, where ORIF most likely leads to good clinical results. However, in patients with 4+ fragment patterns, ORIF did not show statistically significantly worse results concerning the collected clinical values. This study supports the use of the ORIF approach to save the radial head.

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.

Estimating elbow loading conditions through the motion behaviors of subchondral bone density during joint movements

Evaluating complicated stress across the elbow under joint motion remains difficult. Here, we aimed to evaluate the distribution of the subchondral bone density in the normal elbow bones and further characterize their spatial relationships during elbow motion to estimate the loading stress across the articular surface using three-dimensional computed tomography bone models. The normal elbow joint exhibited a consistent distribution pattern of subchondral bone density. High-density regions were distributed in the capitellum and posterior humeral trochlea, sagittal ridge of the ulnar trochlear notch and ulnar-volar side of the radial head. Motion analyses revealed that the high-density regions proximate with elbow flexion with forearm pronation in the radiocapitellar joint and in the fully extended position in the ulnohumeral joint. This reasonably reflects the stress acting on the joint surface under actual loading conditions. These findings suggest that daily activities involving lifting or carrying objects in these positions are stress-prone activities.

Does the polarity of radial head arthroplasty affect functional outcomes? A systematic review and meta-analysis

BACKGROUND

Radial head arthroplasty allows a high degree of customizability, and implant polarity has emerged as an important variable. The purpose of this meta-analysis was to evaluate differences in functional and clinical outcomes between patients receiving monopolar and bipolar radial head prosthetic implants.

METHODS

A systematic review and meta-analysis were employed, and 65 articles were identified in three databases. Twelve articles contained non-English or insufficient text and were consequently excluded, and 20 others did not contain sufficient data or follow-up. The remaining 33 articles were qualitatively and quantitatively reviewed.

RESULTS

In total, 33 populations were identified, with 809 unduplicated patients: 565 with monopolar and 244 with bipolar implants. In these respective patients, the mean follow-up was 40.2 and 56.9 months. Average Mayo Elbow Performance Score were 86.7 and 87.4 (P=0.80), respectively; average Disability of the Arm, Shoulder, and Hand scores were 17.9 and 14.7 (P=0.47), and average final flexion/extension arcs were 119.4° and 118.7° (P=0.48). Revision rates were 4.07% and 6.56%, while complication rates were 19.65% and 20.08% in the respective monopolar and bipolar patients. These increased relative risks associated with bipolar implants were not significant.

CONCLUSIONS

Radial head implant polarity does not appear to affect functional outcomes. While bipolar prosthetic design may increase the risks of revision and complications, the increases were not significant. Level of evidence: IV.

Biomechanical study of 3D-printed titanium alloy pad for repairing glenoid bone defect

Background: The purpose of this study was to investigate the effect of 3D-printed technology to repair glenoid bone defect on shoulder joint stability. Methods: The shoulder joints of 25 male cadavers were tested. The 3D-printed glenoid pad was designed and fabricated. The specimens were divided into 5 groups. Group A: no bone defect and the structure of the glenoid labrum and joint capsule was intact; Group B: Anterior inferior bone defect of the shoulder glenoid; Group C: a pad with a width of 2 mm was installed; Group D: a pad with a width of 4 mm was installed; Group E: a pad with a width of 6 mm was installed. This study measured the distance the humeral head moved forward at the time of glenohumeral dislocation and the maximum load required to dislocate the shoulder. Results: The shoulder joint stability and humerus displacement was significantly lower in groups B and C compared with group A (p < .05). Compared with group A, the stability of the shoulder joint of group D was significantly improved (p < .05). However, there was no significant difference in humerus displacement between groups D and A (p > .05). In addition, compared with group A, shoulder joint stability was significantly increased and humerus displacement was significantly decreased in group E (p < .05). Conclusion: The 3D-printed technology can be used to make the shoulder glenoid pad to perfectly restore the geometric shape of the shoulder glenoid articular surface. Moreover, the 3D-printed pad is 2 mm larger than the normal glenoid width to restore the initial stability of the shoulder joint.

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.

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.

Early aseptic loosening of a press-fit radial head prosthesis - A case series of 6 patients

OBJECTIVE

Radial head arthroplasty (RHA) is the principal treatment option for comminuted radial head (RH) fractures. Here, we present six cases of failed RHA using a modular monopolar press-fit RHA that was subsequently withdrawn from the market because it was associated with a high incidence of loosening.

METHODS

We retrospectively collected data from six patients who had received Radial Head Prothesis System^TM at our centre between July 2015 and June 2016. The average follow-up was 40 months.

RESULTS

Aseptic loosening of the stem affected five (83%) of the six RHA. Four of these were symptomatic and RHA removal was performed. For these patients, the pain subsided and their elbow range of motion (ROM) improved.

CONCLUSION

While the ideal design for an RHA is still debatable, RHA is an efficient treatment option that restores elbow stability and function after a comminuted RH fracture. Importantly, removal of the prosthesis is an effective remedy following RHA associated elbow pain and decreased ROM.

[Radial head arthropolasty in unreconstructable comminuted fractures of the radial head: Long-term results and factors influencing the outcome]

BACKGROUND

Radial head arthroplasty is recognized as the gold standard in the treatment of patients with unreconstructable radial head fractures.

OBJECTIVE

The aim of this retrospective study was to investigate the long-term results after prosthetic replacement of the radial head and in a subgroup analysis to identify factors which influence the outcome.

MATERIAL AND METHODS

A total of 48 patients with unreconstructable fractures of the radial head and neck were treated by cementless radial head arthroplasty between 05/2008 and 10/2018 (30 bipolar prosthesis type rHead Recon, 18 monopolar prosthesis type MoPyc). After a mean follow-up of 4.6 years 39 patients were assessed clinically and radiologically.

RESULTS

The median MEP score was 95 points. Compared to the uninjured side the median range of motion was reduced by 10° for extension/flexion as well as for pronation/supination. In 36 of 39 cases an osseous integration of the prosthesis could be documented. One prosthesis had to be removed after 23 months because of painful loosening. Overlengthening was present in 11 cases (28%), 25 patients (64%) had subcollar bone resorption with a stable osteointegrated stem. Nonbridging heterotopic ossification was observed in 15 patients (38%), 16 patients (41%) showed posttraumatic arthrosis. Patients with sustained elbow dislocation had a significantly worse function in the MEP score and tended to develop an arthrosis more frequently. Ulnohumeral joint degeneration was significantly increased when overlengthening was present.

CONCLUSION

Radial head arthroplasty is an effective treatment option for unreconstructable fractures of the radial head and can provide good to excellent mid-term to long-term results. Sustained elbow dislocation as well as overlengthening of the prosthesis had a negative impact on the clinical outcome.

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.

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.

RADIAL head arthroplasty: does ligaments repair influence outcomes? A minimum two years follow-up radiographic multi-center study

PURPOSE

The current indication for comminuted radial head fractures is radial head arthroplasty (RHA). The main purpose of this study was to investigate any statistical differences in terms of prosthesis revision or removal and radiographic degenerative changes by comparing patients who underwent RHA and ligaments repair to those who underwent only RHA implant at minimum two years follow-up. The secondary aim was to delineate a trend profile of RHA implants.

METHODS

All patients who underwent RHA surgery for traumatic pathology between January 2012 and December 2017 were eligible. Two researchers independently and retrospectively reviewed the patients' charts and collected the following data: type of prosthesis, associated surgical procedures and revision surgery. They also looked for any radiographic sign of prosthesis loosening, overstuffing, capitellar osteopenia, heterotopic ossification and degenerative changes. No clinical evaluation was performed.

RESULTS

In 6 years, 124 RHA were implanted (74 female, 50 male, mean age 56). The main diagnoses were: terrible triad, trans-olecranon fracture and isolated radial head fracture. It was found no significant statistical difference between the 2 groups; nevertheless, the cohort of patients that underwent ligaments repair had a lower revision rate in comparison with the other. Suture of the annular ligament seems to be critical. The overall revision rate was 10.5%.

CONCLUSION

This multi-center study found no evidence that ligaments repair, as an associated surgical procedure, improves RHA longevity, except for annular ligament. Nevertheless, it seems to prevent degenerative changes at midterm follow-up.

Factors influencing the mid-term radiological and functional outcomes of 41 post-fracture bipolar radial head arthroplasty cases at a mean follow-up of 87 months

INTRODUCTION

When treating comminuted radial head fractures that cannot be adequately fixed, the next option is arthroplasty (radial head replacement). We hypothesized that the radiological and functional outcomes of bipolar mobile cup radial head arthroplasty is not influenced by the length of follow-up but instead by the correct positioning of the implant intraoperatively and by the presence of associated bone or ligament injuries.

PATIENTS AND METHODS

Between May 1998 and December 2016, 82 cases of radial head arthroplasty were performed at our hospital. The mean age of patients at the time of arthroplasty was 53 years (22-81). Ligament or bone injuries complicated the radial head fractures in 70% of patients.

RESULTS

For the final assessment, 41 patients were reviewed and included in the statistical analysis with a mean of 82 months (12-228). The mean MEPS at the final assessment was 88.7 (61-100). There were 23 excellent, 9 good, 9 average and 0 poor results. The average DASH score was 18.7 (0-55). The average VAS for pain was 1.0 (0-5). Five patients (12%) required surgical revision, including one implant change. Our statistical analysis found no relationship between follow-up time and functional outcomes. The appearance of periprosthetic radiolucent lines was not affected by the length of follow-up. Associated bone or ligament injuries significantly increased the probability of periprosthetic radiolucent lines, humeroulnar joint degeneration and decentering of the implanted cup. Radiological evidence of a suspended implant was associated with significantly worse functional outcomes.

CONCLUSION

This study confirms the long-term stability of the clinical outcomes of radial head arthroplasty. There was no relationship between worsening radiological appearance of the implant and the clinical outcomes. It is critical that this implant not be oversized or suspended, as this can trigger premature capitellar erosion and painful stiffness of the operated elbow.

LEVEL OF EVIDENCE

IV; systematic retrospective analysis.

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.

Midterm outcomes of 146 EVOLVE Proline modular radial head prostheses: a systematic review

INTRODUCTION

The EVOLVE implant (Wright Medical Technology, Arlington, TN, USA) is a modular loose-fitting radial head prosthesis. The primary objective was to synthesize all available literature investigating the midterm clinical outcomes of the EVOLVE implant.

MATERIALS AND METHODS

An electronic literature search in Pubmed/Medline, Scopus, EMBASE, and Cochrane library was performed querying for studies published in 2000-2017. Articles describing clinical and radiographical outcomes as well as reoperation were included. Outcomes of interest included range of motion, Mayo Elbow Performance Score, Disabilities of the Arm Shoulder and Hand, radiographic outcome, and reason for reoperation.

RESULTS

A total of five articles consisting of 146 patients with EVOLVE implants were included. Mean patient age was 57.4 years (range 22-84), and 43.8% were males (n = 64). Mean follow-up was 4.8 years (range 1-14). Mean Mayo Elbow Performance Score and Disabilities of the Arm Shoulder and Hand score were 87.6 (range 30-100) and 18.9 (range 0-82), respectively. Midterm clinical results were good or excellent (Mayo Elbow Performance Score > 74) in 94 patients. Reoperation was observed in 12 patients, with implant revision required in 2 patients. The primary reason for reoperation was persistent stiffness (n = 9).

CONCLUSION

Midterm outcomes of EVOLVE radial head prosthesis are satisfactory, and associated complication rates are low. Loose-fit implant method appears to be a reliable approach to avoid failure of radial head prosthesis by painful loosening.

Downsizing effect of a modular radial head prosthesis on the lateral collateral ligament of the elbow: A cadaveric study

BACKGROUND

It remains unclear how the head and stem diameters for the radial head prosthesis could affect mechanical properties of the lateral collateral ligament measured by strain changes during elbow and forearm motions.

METHODS

Eight cadaveric specimens were secured to the device, which allows elbow flexion-extension and forearm pro-supination. Using six different implant combinations comprising 2 sizes for the head (long- and short-axis of the native head) and 3 sizes for the stem (press-fit, -1 mm, and -2 mm downsizing), prostheses were attached via the posterior approach. A differential variable reluctance transducer placed on the central portion of the radial collateral ligament were used for strain measurement with elbow flexion at 0°, 30°, 60°, and 90°. At each position, the strain patterns with the forearm in the neutral and 45° pro-supination positions were also assessed.

FINDINGS

Specimens implanted with long-axis head component showed greater increases in the ligament strain during elbow flexion than intact specimens or those implanted with short-axis head. Compared to press-fit stem, implants with downsizing to -1 mm approximated strain patterns during pro-supination with elbow extension to intact condition.

INTERPRETATION

Morphologic variation of the head and stem components in radial head prostheses led to altered strain patterns in the lateral collateral ligament during elbow and forearm motions. A short-axis head component can be used to prevent excessive strain changes after the prosthesis application. Downsizing of the stem component might be an option for approximating the biomechanics at the radiocapitellar joint during forearm rotation to the intact elbow.

Relationship between the tilt angle of bipolar radial head prostheses and radiological radiocapitellar instability

OBJECTIVE

This study aimed to radiologically assess the relationship between the tilt angle of the bipolar radial head prostheses and radiocapitellar instability.

METHODS

In this radiological study, 28 consecutive patients (13 females and 15 males: mean age=47 years and age range=23-77 years) who underwent cemented bipolar radial head arthroplasty (Judet CRF II) because of comminuted radial head fracture with elbow instability were retrospectively reviewed.

RESULTS

There was excellent intra- and interobserver reliability for the measurements of the tilt angle and the radiocapitellar distance. ICC for interobserver reliability of the tilt angle was 0.93, and ICC for intraobserver reliability for the 2 observers was 0.96 and 0.97, respectively. ICC for interobserver reliability of the radiocapitellar distance was 0.87, and ICC for intraobserver reliability for the 2 observers was 0.91 and 0.93, respectively. The mean tilt angle was 17.6° (range=1°-35°), and the mean radiocapitellar distance was 8 mm (range=1-17 mm). Pearson's correlation revealed a strong significant positive correlation between the tilt angle and the radiocapitellar distance (r=0.77 and p<0.001).

CONCLUSION

Evidence from this study has demonstrated a strong positive correlation between the tilt angle of bipolar radial head prostheses and radiocapitellar instability. The tilt angle can be used as an indicator of radiocapitellar joint instability following bipolar radial head prostheses.

LEVEL OF EVIDENCE

Level IV, Diagnostic study.

Isolated Proximal Radioulnar Joint Instability: Anatomy, Clinical Presentation, and Current Treatment Options

Isolated proximal radioulnar joint instability is an uncommon and often challenging problem that may manifest as recurrent instability of the proximal aspect of the radius, usually during forearm pronation and supination. Instability is due to deficiency of the stabilizing structures around the proximal aspect of the radius, and biomechanical studies have highlighted the importance of the annular ligament and the interosseous membrane in both transverse and longitudinal plane stability. Reconstruction of the stabilizing structures around the radial head often is indicated in cases of recurrent instability and includes joint-preserving procedures such as annular ligament reconstruction, proximal ulnar osteotomy, and interosseous membrane reconstruction. Rarely, salvage procedures such as interpositional arthroplasty or 1-bone forearm reconstruction are necessary. A thorough understanding of the anatomic structures that stabilize the proximal aspect of the radius and the complexities of forearm biomechanics is required in order to successfully diagnose and manage this condition.

Radial head fractures

The shape and size of the radial head is highly variable but correlates to the contralateral side. The radial head is a secondary stabilizer to valgus stress and provides lateral stability. The modified Mason-Hotchkiss classification is the most commonly used and describes three types, depending on the number of fragments and their displacement. Type 1 fractures are typically treated conservatively. Surgical reduction and fixation are recommended for type 2 fractures, if there is a mechanical block to motion. This can be done arthroscopically or open. Controversy exists for two-part fractures with >2 mm and <5 mm displacement, without a mechanical bloc as good results have been published with conservative treatment. Type 3 fractures are often treated with radial head replacement. Although radial head resection is also an option as long-term results have been shown to be favourable. Radial head arthroplasty is recommended in type 3 fractures with ligamentous injury or proximal ulna fractures. Failure of primary radial head replacement may be due to several factors. Identification of the cause of failure is essential. Failed radial head arthroplasty can be treated by implant removal alone, interposition arthroplasty, revision radial head replacement either as a single stage or two-stage procedure.

Comparison of bipolar and monopolar radial head prostheses in elbow fracture-dislocation

INTRODUCTION

The role of bipolar radial head prostheses (RHP) in elbow fracture-dislocation is controversial, with some reports of poorer stabilization than with monopolar designs. The aim of the present study was to compare mono- versus bi-polar RHPs in elbow fracture-dislocation. The study hypothesis was that mono- and bi-polar RHPs do not differ in clinical and radiological results, complications or revision rates.

MATERIAL AND METHODS

A single-center retrospective study included 58 patients, with a mean age of 55 years (range, 21-84 years). All received RHP for elbow dislocation with association: terrible triad, Monteggia fracture-dislocation, transolecranal dislocation or divergent dislocation. Two groups were compared: Mono-RHP, with monopolar prosthesis (n=40), and Bi-RHP, with bipolar prosthesis (n=18). All patients underwent clinical and radiological examination at last follow-up.

RESULTS

Mean follow-up was 42.7 months (range, 12-131 months). There were no significant (p>0.05) inter-group differences in range of motion or Mayo Elbow Performance Score. Mono- versus bi-polar design did not correlate with onset of complications (p=0.89), surgical revision (p=0.71), persistent or recurrent instability (p=0.59), or ulnohumeral (p=0.62) or capitulum (p=0.159) osteoarthritis at last follow-up.

DISCUSSION AND CONCLUSION

No differences were found between mono- and bi-polar RHPs in the treatment of elbow fracture-dislocation. Clinical and radiographic results were similar, as were complications and revision rates. The literature is inconclusive, reporting contradictory conclusions. We see no contraindications to bipolar RHPs in elbow dislocation with association, notably terrible triad injury.

LEVEL OF EVIDENCE

III, Retrospective case-control study.

Surgical treatment of the radial head is critical to the outcome of Monteggia-like lesions

Aims

The aim of this study was to evaluate the outcome of Monteggia-like lesions at midterm follow-up and to determine whether the surgical treatment of the radial head influences the clinical and radiological results.

Patients and Methods

A total of 78 patients with a Monteggia-like lesion, including 44 women and 34 men with a mean age of 54.7 years (19 to 80), were available for assessment after a mean 4.6 years (2 to 9.2). The outcome was assessed using the Mayo Elbow Performance Score (MEPS), Oxford Elbow Score (OES), Mayo Modified Wrist Score (MMWS), and The Disabilities of the Arm, Shoulder and Hand (DASH) score. Radiographs were analyzed for all patients. A total of 12 Mason type I, 16 type II, and 36 type III fractures were included. Surgical treatment consisted of screw fixation for all type II and reconstructable type III fractures, while radial head arthroplasty (RHA) or excision was performed if reconstruction was not possible.

Results

The mean MEPS was 88.9 (40 to 100), mean OES was 40.1 (25 to 48), mean MMWS was 88.1 (50 to 100), mean DASH score was 14.7 (0 to 60.2), and mean movement was 114° (sd 27) in extension/flexion and 155° (sd 37) in pronation/supination. Mason III fractures, particularly those with an associated coronoid fracture treated with RHA, had a significantly poorer outcome. Suboptimal results were also identified in patients who had degenerative changes or heterotopic ossification on their latest radiograph. In contrast, all patients with successful radial head reconstruction or excision had a good outcome.

Conclusion

Good outcomes can be achieved in Monteggia-like lesions with Mason II and III fractures, when reconstruction is possible. Otherwise, RHA is a reliable option with satisfactory outcomes, especially in patients with ligamenteous instability. Whether the radial head should be excised remains debatable, although good results were achieved in patients with ligamentous stability and in those with complications after RHA. Cite this article: Bone Joint J 2019;101-B:1512–1519

Joint contact areas after radial head arthroplasty: a comparative study of 3 prostheses

BACKGROUND

Contact stresses of radial head prostheses remain a concern, potentially leading to early capitellar cartilage wear and erosion. In particular, point contact or edge loading could have a detrimental effect. The purpose of this study was to compare 3 different types of radial head prostheses in terms of joint contact areas with each other and with the native situation. The hypothesis was that the joint contact areas would be lower after monopolar arthroplasty.

METHODS

Seven fresh-frozen cadaveric upper limbs were used. Radiocapitellar contact areas of a monopolar design, a straight-neck bipolar design, and an angled-neck bipolar design were compared with each other and with the native joint. After standardized preparation, polysiloxane was injected into the loaded radiocapitellar joint to create a cast from which the joint contact area was measured. Measurements were performed at 3 angles of elbow flexion and in 3 different forearm positions.

RESULTS

In the native elbow, contact areas were highest in supination. Elbow flexion had no significant effect on native and prosthetic joint contact areas. Contact areas were decreased for all types of arthroplasties compared with the native joint (from 11% to 53%). No significant contact area difference was found between the 3 designs. However, bipolar prostheses showed lateral subluxation in neutral forearm rotation, resulting in a significant decrease in the contact areas from pronation to the neutral position.

CONCLUSIONS

All types of radial head prostheses tested showed a significant decrease in radiocapitellar contact area compared with the native joint. Bipolar designs led to subluxation of the radial head, further decreasing radiocapitellar contact.

Surgical treatment of radial head isolated Mason III fractures

INTRODUCTION

In this retrospective study we have analyzed a consecutive series of patients affected by isolated radial head Mason III fractures and treated with bone resection or prosthesis.

PATIENTS AND METHODS

This study includes 24 patients affected by fractures mentioned above and treated between July 2009 and November 2015. 15 patients (average age 48 y.o.) have been treated with prosthesis. The remaining 9 (average age 573) have been treated with a capitellectomy instead. From a clinical point of view, we have evaluated the patients according to main performance indicators such as range of motion, pain, instability and Mayo Elbow Performance Score as parameters.

RESULTS

We have found similar results in both group, with an average MEPS value of 95 in the prosthesis group and 966 in the radial head resection group. The range of motion was similar too: between 1,3° and 1203° in the first group and between 4,4° and 120° in the second one. No significant complication has detected in any patient.

DISCUSSION

According to most recent literature, it is not precisely defined how to treat isolated Mason III fractures, contrary to what is defined in more complex pattern, in which prosthesis are now evaluated as the best indication. Due to radial head limited contribution to elbow stability, in absence of other bony or ligamentous lesions both capitellectomy and prosthesis can be good treatment in this kind of fracture.

CONCLUSION

According to our experience and to the most recent literature, we recommend prosthesis in patient younger than 50 y.o., high demanding or manual worker, while in other cases we think that radial head resection can be the treatment of choice.

Regional Distribution of Articular Cartilage Thickness in the Elbow Joint: A 3-Dimensional Study in Elderly Humans

During elbow procedures, reconstruction of the joint (including the articular cartilage) is important in order to restore elbow function; however, the regional distribution of elbow cartilage is not completely understood. The purpose of the present study was to investigate the 3-dimensional (3-D) distribution patterns of cartilage thickness of elbow bones (including the distal part of the humerus, proximal part of the ulna, and radial head) in order to elucidate the morphological relationship among them.

WITHDRAWN: Surgical treatment of radial head isolated Mason III fractures

The Publisher regrets that this article is an accidental duplication of an article that has already been published in Injury, 50(2) 2019 382–385, https://doi.org/https://doi.org/10.1016/j.injury.2018.11.044. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Radial head arthroplasty for radial head fractures: a clinical and radiological comparison of monopolar and bipolar radial head arthroplasty at a mean follow-up of 6 years

PURPOSE

The purpose of this study was to compare clinical and radiographic outcomes of bipolar and monopolar radial head arthroplasty in treatment of radial head fracture at a mean follow-up of 6 years.

METHODS

A retrospective multicentre cohort study of 30 patients treated for unreconstructable radial head fractures. Patients were treated either with a cemented bipolar or an uncemented monopolar radial head arthroplasty. All patients included were evaluated with patient-rated outcome questionnaire, physical examination, and radiographic evaluation at a mean of 6 years (range, 2-12 years) postoperatively.

RESULTS

There was no statistical difference in QuickDASH between the bipolar or monopolar groups. The majority of patients had no to little pain during rest. Neither flexion nor extension of the injured arm was significantly affected by the type of prosthesis. None of the patients in the bipolar group had any secondary surgery at the time of follow-up. In the monopolar group, four patients required removal of the arthroplasty. Signs of ulnohumeral degenerative changes were seen in the majority of patients in both groups (55% in the monopolar group, 92% in the bipolar group).

CONCLUSION

In this retrospective cohort study comparing a bipolar and a monopolar radial head arthroplasty for treatment of radial head fractures, we found comparable functional outcome but more revision procedures in the monopolar group at a mean follow-up of 6 years.

The Patient-Specific Implant Created with 3D Printing Technology in Treatment of the Irreparable Radial Head in Chronic Persistent Elbow Instability

Successful treatment of the chronic persistent elbow instability is a challenge for orthopedic surgeons. In this form, it is important to recognize and restore the osseous stabilizer in order to obtain the concentric reduction. In the present report, we describe a case of such injury with irreparable radial head treated with patient-specific radial head prosthesis which was created with 3D printing technology. To our knowledge, this is the first report in clinical use of this kind of prosthesis for the radial head fracture. At a 24-month follow-up visit, the patient was satisfied with the functional outcomes. The Mayo Elbow Performance Index (MEPI) increased from 20 points at the preoperative day to 85 points, and the patient-based Disabilities of the Arm, Shoulder, and Hand (DASH) was reduced from 88.33 points to 28.33 points. Due to the favorable result, replacement of the radial head with the patient-specific implant could be a useful treatment for the irreparable radial head in chronic persistent elbow instability.

Anthropometric Study of the Radiocapitellar Joint

PURPOSE

There is scant knowledge about the relationship between the size of the radial head and the size of the capitellum. Also, no data exist comparing the size of the capitellum between the left and the right elbow.

METHODS

Eight pairs of elbows and 12 single elbows from fresh-frozen cadavers were obtained for this study. The vertical height and anterior width of the capitellum were measured with digital calipers. Four different measurements were performed at the radial head: longest outer diameter, shortest outer diameter, the long dish diameter, and short dish diameter. The Pearson intrarater intraclass correlation coefficients were obtained for all measurements.

RESULTS

For the paired elbows, the correlations ranged between 0.95 and 0.96 for the capitellar dimensions and 0.77 and 0.98 for the radial head dimensions. The correlations between the long outer diameter of the radial head with the vertical height and the anterior width of the capitellum were 0.8 and 0.9, respectively.

CONCLUSIONS

There is a high correlation between the long outer diameter of the radial head and the vertical height of the capitellum as well its anterior width. There is also a high correlation between the left and the right elbow.

CLINICAL RELEVANCE

These findings are relevant to radiocapitellar arthroplasty and may be useful for radiocapitellar prosthetic design as well as in the preoperative planning of cases in which the radial head and/or the capitellum is destroyed.

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.

Short to midterm outcomes of one hundred and seventy one MoPyC radial head prostheses: meta-analysis

BACKGROUND

The MoPyC implant is an uncemented long-stemmed radial head prosthesis that obtains primary press-fit fixation via controlled expansion of the stem. Current literature regarding MoPyC implants appears promising; however, sample sizes in these studies are small. Our primary objective was to evaluate the short- to midterm clinical outcomes of a large sample of the MoPyC prostheses. The secondary objective was to determine the reasons for failure of the MoPyC devices.

METHODS

Four electronic databases were queried for literature published between January 2000 and March 2017. Articles describing clinical and radiographic outcomes as well as reasons for reoperation were included. A meta-analysis was performed to obtain range of motion, mean Mayo Elbow Performance score (MEPS), radiographic outcome, and reason for failure.

RESULTS

A total of five articles describing 171 patients (82 males) with MoPyC implants were included. Mean patient age and follow-up were 52 years (18-79) and 3.1 years (1-9), respectively. Midterm clinical results were good or excellent (MEPS > 74) in 157 patients. Overall complication rate was low (n = 22), while periprosthetic osteolysis was reported in 78 patients. Nineteen patients returned to the operating room, with implant revision being required in ten patients. The two primary reasons for failure were (intra-)prosthetic dislocation (n = 8) followed by stiffness (n = 7); no painful loosening was described.

CONCLUSION

Short- to midterm outcomes of MoPyC prostheses are satisfactory and complications associated are low. The use of stem auto-expansion as a mode of obtaining primary fixation in radial head arthroplasty appears to be an effective solution for reducing the risk of painful loosening.

The minimum follow-up required for radial head arthroplasty: a meta-analysis

AIMS

The primary aim of this study was to define the standard minimum follow-up required to produce a reliable estimate of the rate of re-operation after radial head arthroplasty (RHA). The secondary objective was to define the leading reasons for re-operation.

MATERIALS AND METHODS

Four electronic databases, between January 2000 and March 2017 were searched. Articles reporting reasons for re-operation (Group I) and results (Group II) after RHA were included. In Group I, a meta-analysis was performed to obtain the standard minimum follow-up, the mean time to re-operation and the reason for failure. In Group II, the minimum follow-up for each study was compared with the standard minimum follow-up.

RESULTS

A total of 40 studies were analysed: three were Group I and included 80 implants and 37 were Group II and included 1192 implants. In Group I, the mean time to re-operation was 1.37 years (0 to 11.25), the standard minimum follow-up was 3.25 years; painful loosening was the main indication for re-operation. In Group II, 33 Group II articles (89.2%) reported a minimum follow-up of < 3.25 years.

CONCLUSION

The literature does not provide a reliable estimate of the rate of re-operation after RHA. The reproducibility of results would be improved by using a minimum follow-up of three years combined with a consensus of the definition of the reasons for failure after RHA. Cite this article: Bone Joint J 2017;99-B:1561-70.

Tight-fitting radial head prosthesis: does stem size help prevent painful loosening?

INTRODUCTION

The most common reason for removal of well-fixed radial head prostheses is painful loosening. We hypothesised that short-stemmed prostheses, used for radial head arthroplasty, are not associated with an increased risk of implant loosening.

METHODS

From 2002 to 2014, 65 patients were enrolled in a retrospective single-centre study. The radial head prostheses were classified as having either a long (30-mm) or short (16- to 22-mm) stem. The long-stemmed implants comprised 30 GUEPAR® DePuy Synthes (West Chester, PA, USA) and 20 Evolutive® Aston Medical (Saint-Etienne, France) devices; the short-stemmed implants comprised nine RECON and six STANDARD rHead® SBI-Stryker (Morrisville, PA, USA) devices. At last follow-up, clinical (range of motion, Disabilities of the Arm, Shoulder, and Hand score, Mayo Elbow Performance score) and radiographic (osteolysis) outcomes were assessed.

RESULTS

At a mean follow-up of 76.78 months (24-141), the rate of painful loosening [6 (40%) vs 8 (16%), p = 0.047] and osteolysis [12 (80%) vs 23 (46%), p = 0.02] were significantly higher in patients with short-stemmed versus long-stemmed implants. Despite the significant difference in loosening between stems as groups, individual stem length was not determined.

CONCLUSIONS

Tight-fitting implants with short stems are more prone to painful loosening.

Mid-term outcomes of 77 modular radial head prostheses

AIMS

Radial head arthroplasty (RHA) may be used in the treatment of non-reconstructable radial head fractures. The aim of this study was to evaluate the mid-term clinical and radiographic results of RHA.

PATIENTS AND METHODS

Between 2002 and 2014, 77 RHAs were implanted in 54 men and 23 women with either acute injuries (54) or with traumatic sequelae (23) of a fracture of the radial head. Four designs of RHA were used, including the Guepar (Small Bone Innovations (SBi)/Stryker; 36), Evolutive (Aston Medical; 24), rHead RECON (SBi/Stryker; ten) or rHead STANDARD (SBi/Stryker; 7) prostheses. The mean follow-up was 74.0 months (standard deviation (sd) 38.6; 24 to 141). The indication for further surgery, range of movement, mean Mayo Elbow Performance (MEP) score, quick Disabilities of the Arm, Shoulder and Hand (quickDASH) score, osteolysis and positioning of the implant were also assessed according to the design, and acute or delayed use.

RESULTS

The mean MEP and quickDASH scores were 90.2 (sd 14; 45 to 100), and 14.0 points (sd 12; 1.2 to 52.5), respectively. There were no significant differences between RHA performed in acute or delayed fashion. There were 30 re-operations (19 with, and 11 without removal of the implant) during the first three post-operative years. Painful loosening was the primary indication for removal in 14 patients. Short-stemmed prostheses (16 mm to 22 mm in length) were also associated with an increased risk of painful loosening (odds ratio 3.54 (1.02 to 12.2), p = 0.045). Radiocapitellar instability was the primary indication for re-operation with retention of the implant (5). The overall survival of the RHA, free from re-operation, was 60.8% (sd 5.7%) at ten years.

CONCLUSION

Bipolar and press-fit RHA gives unsatisfactory mid-term outcomes in the treatment of acute fractures of the radial head or their sequelae. The outcome may vary according to the design of the implant. The rate of re-operation during the first three years is predictive of the long-term survival in tight-fitting RHAs. Cite this article: Bone Joint J 2017;99-B1197-1203.

Radial Neck Dilatory Remodeling After Radial Head Arthroplasty With an Uncemented, Press Fit, Fully Chemically Etched Stem Design

OBJECTIVES

To compare the radiographic outcomes of 2 widely used side loading, press fit, RHA implants used to reconstruct complex elbow trauma.

DESIGN

Retrospective cohort study.

SETTING

Level-1 Academic trauma center.

PARTICIPANTS

Patients undergoing RHA.

INTERVENTION

Cohort 1 received Synthes Radial Head Prosthesis. Cohort 2 received Biomet ExploR Radial Head Replacement.

MAIN OUTCOME MEASUREMENTS

Radial neck dilatory remodeling.

RESULTS

Eighty-two subjects were included in final analysis, 63 from the Biomet Cohort, and 19 from Synthes cohort. Demographic and injury characteristics were similar among cohorts. Radial neck dilatory remodeling as well as periprosthetic radiographic lucency were seen significantly more frequently and to a significantly greater degree in the Synthes cohort. The average percentage of dilatory remodeling of the Synthes cohort was 34.9% and that of the Biomet cohort was 2.7%. There were no differences in rates of revision surgery.

CONCLUSIONS

Our study demonstrates significant radiographic differences between 2 frequently used RHA implants. Radial neck dilatory remodeling is a common, rapidly progressive, and dramatic finding frequently seen with the Synthes Radial Head Prosthesis.

LEVEL OF EVIDENCE

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

Current concepts in elbow arthroplasty

Distal humeral replacement and the total elbow are two commonly-used arthroplasties

Each prosthesis has evolving indications and surgical techniques

Recent changes in device design and implantation methods are due to biomechanical and clinical outcome-based research

New prostheses and methods provide: better elbow kinematics, more durable bearings and longer-lasting joint replacement potential

Cite this article: EFORT Open Rev 2017;2:83-88. DOI: 10.1302/2058-5241.2.160064

Complex elbow instability: surgical management of elbow fracture dislocations

There are three main patterns of complex elbow instability: posterolateral (terrible triad), varus posteromedial (anteromedial coronoid fracture with lateral collateral ligament complex disruption), and trans-olecranon fracture dislocations.Radial head fractures, in the setting of complex elbow instability, often require internal fixation or arthroplasty; the outcome of radial head replacement is dictated by adequate selection of the head diameter, correct restoration of radial length, and proper alignment and tracking.Small coronoid fractures can be ignored. Larger coronoid fractures, especially those involving the anteromedial facet, require fixation or graft reconstruction, particularly in the presence of incongruity.The lateral collateral ligament complex should be repaired whenever disrupted. Medial collateral ligament disruptions seem to heal reliably without surgical repair provided all other involved structures are addressed.The most common mistakes in the management of trans-olecranon fracture dislocations are suboptimal fixation, lack of fixation of coronoid fragments, and lack of restoration of the natural dorsal angulation of the ulna. Cite this article: Sanchez-Sotelo J, Morrey M. Complex elbow instability. EFORT Open Rev 2016;1:183-190.

Radiocapitellar contact characteristics during prosthetic radial head subluxation

BACKGROUND

Metallic radial head prostheses are often used in the management of comminuted radial head fractures and elbow instability. We hypothesized that during radiocapitellar subluxation, the contact pressure characteristics of an anatomic radial head prosthesis will more closely mimic those of the native radial head compared with a monopolar circular or a bipolar circular radial head design.

MATERIALS AND METHODS

With use of 6 fresh frozen cadaver elbows, mean radiocapitellar contact pressures, contact areas, and peak pressures of the native radial head were assessed at 0, 2, 4, and 6 mm of posterior subluxation. These assessments were repeated after the native radial head was replaced with anatomic, monopolar circular and bipolar circular prostheses.

RESULTS

The joint contact pressures increased with the native and the prosthetic radial head subluxation. The mean contact pressures for the native radial head and anatomic prosthesis increased progressively and significantly from 0 to 6 mm of subluxation (native, 0.6 ± 0.0 MPa to 1.9 ± 0.2 MPa; anatomic, 0.7 ± 0.0 MPa to 2.1 ± 0.3 MPa; P < .0001). The contact pressures with the monopolar and bipolar prostheses were significantly higher at baseline and did not change significantly further with subluxation (monopolar, 2.0 ± 0.1 MPa to 2.2 ± 0.2 MPa [P = .31]; bipolar, 1.7 ± 0.1 MPa to 1.9 ± 0.1 MPa [P = .12]). The pattern of increase in contact pressures with the anatomic prosthesis mimicked that of the native radial head. Conversely, the circular prostheses started out with higher contact pressures that stayed elevated.

CONCLUSION

The articular surface design of a radial head prosthesis is an important determinant of joint contact pressures.

[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.

Press-fit bipolar radial head arthroplasty, midterm results

BACKGROUND

Theoretical advantages of bipolar compared with monopolar radial head arthroplasty include better accommodation of radiocapitellar malalignment, reduction of capitellar abrasion, and reduction of stress at the bone-implant interfaces. Our purpose was to report the midterm results of press-fit bipolar radial head arthroplasty.

METHODS

Thirty patients were treated by press-fit bipolar radial head arthroplasty for acute fracture of the radial head, failed earlier treatment, or post-traumatic sequelae. Three patients were lost to follow-up. Results are presented for the remaining 27 patients.

RESULTS

At mean follow-up of 48 months (range, 28-73), there had been 3 (11%) revisions. Two involved conversion to prosthetic radiocapitellar hemiarthroplasty for symptomatic capitellar abrasion; a third involved exchange of the articular component (ie, head) for instability. In all, the stems appeared well fixed. A prosthesis in a subluxed position accounted for the 1 (4%) additional radiologic failure. The average flexion-extension arc was 136° (range, 120°-145°), and the average pronation-supination arc was 138° (range, 70°-180°). According to the Mayo Elbow Performance Score, the combined excellent and good results accounted for 70%.

CONCLUSIONS

The overall midterm outcome of this series of 30 press-fit bipolar radial head arthroplasties can be considered favorable. Although the revision rate was 11%, the stems were well fixed in all. There was 1 (4%) additional radiologic failure. We suggest considering a press-fit bipolar radial head prosthesis for acute comminuted radial head fractures with limited bone loss of the proximal radius.

Regional Variations in Cartilage Thickness of the Radial Head: Implications for Prosthesis Design

PURPOSE

To characterize the regional variations in cartilage thickness around the radial head.

METHODS

We dissected 27 cadaveric radii and scanned them with computed tomography in neutral position. Three-dimensional cartilage and subchondral bone surface models were generated from computed tomography scans and 2 independent observers processed them through a computer program to obtain cartilage thickness measurements. These measurements were taken at 41 predetermined landmarks around the periphery of the radial head and within the articular dish.

RESULTS

At the periphery of the radial head, cartilage was thickest in the posteromedial region. Thickness values within the articular dish were similar but increased toward the rim. Regional variations within the rim (range, 0.76-1.73 mm) were also detected with the thickest region located anteriorly and thinnest region laterally. In addition, cartilage was significantly thicker in male relative to female specimens.

CONCLUSIONS

Regional variations in cartilage thickness are present around the periphery and rim and within the articular dish of the radial head.

CLINICAL RELEVANCE

Cartilage thickness across the articular dish may contribute to dish depth and the radius of curvature. This may be clinically important for the design of anatomic implants, because accounting for such subtle contours could help to restore radiocapitellar concavity-compression stability better.

The effect of capitellar impaction fractures on radiocapitellar stability

PURPOSE

To determine the effect of capitellar impaction fractures on radiocapitellar stability in a model that simulated a terrible triad injury.

METHODS

Six cadaveric elbows were dissected free of skin and muscles. Tendons were preserved. The lateral collateral ligament was released and repaired (surgical control). Two sizes of capitellar impaction defects were created. After lateral collateral ligament release and repair, we then sequentially created osseous components of a terrible triad injury (partial radial head resection and coronoid fracture) through an olecranon osteotomy that was fixed with a plate. Radiocapitellar stability was recorded after the creation of each new condition.

RESULTS

Significantly less force was required for radiocapitellar subluxation after the creation of 20° and 40° capitellar defects compared with the surgical control (intact capitellum). After the addition of a Mason type II radial head defect and then a coronoid defect, stability decreased significantly further.

CONCLUSIONS

Impaction fractures of the distal portion of the capitellum may contribute to a loss of radiocapitellar stability, particularly in an elbow fracture-dislocation.

CLINICAL RELEVANCE

Because these injuries may be unrecognized, consideration should be given to diagnosing and addressing them.

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.