Radiolucencies surrounding a smooth-stemmed radial head component may not correlate with forearm pain or poor elbow function

Radiographic and clinical comparisons between loose-fit and press-fit stems in monopolar radial head arthroplasty for comminuted radial head fractures

PURPOSE

Few clinical studies have compared the operative outcomes between loose- and press-fit stems in radial head arthroplasty (RHA). We aimed to evaluate the radiographic and clinical results of the two radial head implant concepts.

METHODS

In this retrospective multicenter study, 32 patients (24 women and 8 men) with a mean age of 63.1 years who underwent RHA for comminuted radial head fractures were reviewed between 2005 and 2021. Seventeen patients underwent RHA with a loose-fit stem (L-group), whereas the remaining fifteen patients underwent RHA with a press-fit stem (P-group). The mean follow-up period was 40.1 ± 9.9 months, with the minimum follow-up duration of 12 months. The radiographic findings were evaluated for periprosthetic osteolysis; furthermore, clinical outcomes were analyzed to measure the range of motion of the elbow. The rate of reoperations and prosthesis removal were also reviewed.

RESULTS

The general characteristics of the patients were similar in the two groups. The rate of periprosthetic osteolysis was 17.6% in the L-group, whereas it was 53.3% in the P-group. The mean elbow flexions were 128° and 133° in the L- and P-groups, respectively. The mean elbow extensions were -12° and -9° in the L- and P-groups, respectively. The rate of reoperation was 23.5% in the L-group and 15.2% in the P-group. One patient in the L-group had the prosthesis removed because of surgical site infection, whereas one patient in the P-group had the prosthesis removed owing to painful loosening.

CONCLUSIONS

No significant differences in the clinical outcomes and reoperation rate were observed between the two radial head implant concepts in this study. However, osteolysis occurred more frequently in the P-group. Although patients with periprosthetic osteolysis are currently asymptomatic, they should be carefully followed up for the symptoms in the long term.

The Prevalence of Chronic Interosseous Membrane Lesions Following Mason II and III Radial Head Fractures in Complex Elbow Instability-A Retrospective Observational Cohort Study

PURPOSE

The primary aim of the present study was to assess the prevalence of chronic lesions of the central band of the interosseous membrane (cbIOM) in complex elbow instability (CEI) in a consecutive series of patients who had previously undergone surgical treatment for Mason II and III radial head (RH) fractures. The secondary aim was to define its clinical significance.

METHODS

We performed a retrospective study on a prospective database. Our study population comprised 93 patients affected by CEI with type II or III RH fractures according to Mason's classification who were analyzed in the chronic setting. All patients were treated according to the current therapeutic algorithms. At the last follow-up, the "muscular hernia sign" was investigated by means of a bilateral ultrasonographic examination to assess any chronic cbIOM lesions; the Mayo Elbow Performance Score (MEPS) was used to evaluate the clinical significance of these lesions.

RESULTS

All 93 patients were assessed after a mean time of 7.3 years (range: 2-12). No positive "hernia signs" were found, while five patients (5.4%) displayed an increased laxity of the cbIOM when compared with the contralateral side despite a negative "hernia sign". The clinical outcome in all five patients was excellent with a mean MEPS of 96 (range, 90-100).

CONCLUSIONS

Chronic cbIOM lesions are very rare in CEI with RH fractures. No patients in this large sample displayed a cbIOM complete lesion; in cases with increased laxity, satisfactory mid-term clinical results were observed. Considering that previous studies reported (1) a high prevalence of cbIOM lesions in patients with Mason II and III RH fractures and (2) the current expert opinion about the scarce healing potential of the cbIOM, this study also suggests that the IOM may heal better than previously believed when RH fractures are treated appropriately in the acute setting.

Revision of Failed Radial Head Arthroplasty

BACKGROUND

Revision of radial head arthroplasty (RHA) may be indicated in cases of prosthesis loosening and malposition. Inherent difficulties in revision surgery include poor bone stock and disrupted soft tissue envelope. Although cases of RHA used for revision of failed RHA are rare, there is reasonable expectation for increasing frequency of these cases due to the increasing incidence of primary RHA. Furthermore, there is an increasing demand for postoperative recovery of function; thus, surgeons may consider revising a failed RHA to a new RHA. We report on series of failed RHA which were revised to a new radial head prosthesis.

METHODS

A retrospective review was performed at multiple institutions for a single radial head prosthesis used for revision of a failed radial head prosthesis. Clinical and radiographic outcomes were collected with a minimum of 1 year of follow-up.

RESULTS

Across 11 patients at a mean follow-up of 45.1 months, the mean Mayo Elbow Performance Score was 81.7; mean Disabilities of the Arm, Shoulder, and Hand scores were 24.4; and mean Visual Analog Scale for pain was 0.6. Radiographic analysis yielded no evidence of capitellar wear or stem loosening.

CONCLUSION

A radial head prosthesis can produce satisfactory results when used for revision of a failed prosthesis. Inherent difficulties in revision surgery include the potential for reduced bone stock and a disrupted soft tissue envelope. Elements of prosthesis design which may contribute to effectively managing revision surgery include a long stem with in-growth surface and prosthetic head alignment to the axis of forearm rotation.

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.

Variation in radial head fracture treatment recommendations in terrible triad injuries is not influenced by viewing two-dimensional computed tomography

BACKGROUND

We analyzed association between viewing two-dimensional computed tomography (2D CT) images in addition to radiographs with radial head treatment recommendations after accounting for patient and surgeon factors in a survey-based experiment.

METHODS

One hundred and fifty-four surgeons reviewed 15 patient scenarios with terrible triad fracture dislocations of the elbow. Surgeons were randomized to view either radiographs only or radiographs and 2D CT images. The scenarios randomized patient age, hand dominance, and occupation. For each scenario, surgeons were asked if they would recommend fixation or arthroplasty of the radial head. Multi-level logistic regression analysis identified variables associated with radial head treatment recommendations.

RESULTS

Reviewing 2D CT images in addition to radiographs had no statistical association with treatment recommendations. A higher likelihood of recommending prosthetic arthroplasty was associated with older patient age, patient occupation not requiring manual labor, surgeon practice location in the United States, practicing for five years or less, and the subspecialties "trauma" and "shoulder and elbow."

CONCLUSIONS

The results of this study suggest that in terrible triad injuries, the imaging appearance of radial head fractures has no measurable influence on treatment recommendations. Personal surgeon factors and patient demographic characteristics may have a larger role in surgical decision making. Level of evidence: Level III, therapeutic case-control study.

Acute versus delayed radial head arthroplasty for the treatment of radial head fractures

BACKGROUND

Radial head arthroplasty (RHA) is an important tool in the acute treatment of comminuted radial head and neck fractures. RHA is also performed in a delayed manner after failed open reduction and internal fixation, for fracture malunion or nonunion, and other chronic post-traumatic elbow disorders where restoration of the lateral column of the elbow is considered necessary. The relative efficacy and longevity of acute vs. delayed RHA is unknown. We sought to compare clinical, radiographic, and patient-reported outcomes between these groups.

METHODS

We identified patients ≥18 years old who underwent an RHA between 2000 and 2018 and then extracted 135 total elbows with a mean follow-up of 2.3 years that sustained isolated radial head fractures (30%), terrible triad injuries (66%), or Essex-Lopresti injuries (4%). The acute cohort (RHA: <12 weeks) contained 101 elbows that underwent surgery at a mean of 0.6 weeks (range, 0 days to 7 weeks, 96% <2 weeks) from injury, whereas the delayed cohort (RHA: 12 weeks to 2 years) contained 34 elbows that underwent surgery at a mean of 36 weeks (range, 14-82 weeks) from injury. Patients in the acute group had a higher percentage of terrible triad injuries (75% vs. 40%, P < .001) and Mason 3 fractures (98% vs. 45%, P < .001).

RESULTS

At the final follow-up, 13 of 101 patients in the acute cohort (13%) and 7 of 34 patients in the delayed cohort (21%) required implant revision or resection. A total of 25 patients (25%) in the acute cohort and 12 patients (35%) in the delayed cohort required a reoperation. Kaplan-Meier 2-year survival estimates free of implant resection or revision (90% acute, 86% delayed) and reoperation (76% acute, 70% delayed) were similar between groups. In patients with 5-year follow-up, there was an increased rate of revision or resection in the delayed group (30% vs. 13%). Two-year survival estimates free of radiographic loosening were 80% in the acute cohort vs. 57% in the delayed cohort (P = .04). Mayo Elbow Performance Score at 2 years demonstrated mean scores of 83 and 79 in the acute and delayed groups, respectively, with 71% of the acute cohort and 64% of the delayed cohort achieving good or excellent scores.

CONCLUSIONS

Our results demonstrated that although 2-year Kaplan-Meier survival free of revision or resection estimates and reoperation rates was equivalent between the groups, the delayed group experienced worse Mayo Elbow Performance Score outcomes, a higher revision or resection rate at 5 years, and an increased rate of radiographic loosening.

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

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

Early to midterm radiographic loosening of the press fit radial head prosthesis

BACKGROUND

Radiographic loosening is frequently seen around the radial head (RH) implant. The hypothesis of this study was that radiographic loosening will be more frequent in patients in which the RH prosthesis was implanted due to elbow trauma leading to instability that required lateral collateral ligament repair (LCL).

MATERIALS AND METHODS

A retrospective review of the patients who had RH implantation between 2012 and 2019 was performed. Evaluation included evidence of radiographic loosening, stress shielding, formation of heterotopic ossification, and rate of removal of the implant. Range of motion of the elbow at the latest follow up was also recorded.

RESULTS

At a mean follow up of 18 months (range 1.4 - 80) eight out of 25 patients had radiographic loosening around the implant. The radial head implant was removed in 8 patients (in 3 due to painful radiographic loosening, in 4 due pain without radiographic loosening and in 1 due to infection). Radiographic loosening around the RH implant had no association with LCL repair (p=0.18) or future removal of implant (p=0.18) or the diagnosis of Monteggia lesion (p=0.68). In addition, removal of the RH implant had no association with prior LCL repair (p=0.60) or the diagnosis of Monteggia lesion (p=0.15). Stress shielding was seen in 5 patients and was of no clinical significance. Heterotopic ossification was seen in 12 patients and was classified as Class I in 3, IIA in 3, IIC in 6, according to the Hastings Classification. The average flexion-extension arc was 23° to 130°, and average pronation-supination was 76° to 69°.

CONCLUSION

One third of the patients had radiographic loosening around the RH implant at a mean follow up of 18 months. Pain with or without radiographic loosening were the main reasons for removal of the implant. No associations were found between the development of radiographic loosening and LCL repair at the time of RH replacement. Limitations of this study are: (a) the retrospective design (b). the small sample size and the possibility of a type II statistical error.

Retrospective review of pyrocarbon radial head replacement

Background

Radial head arthroplasty is the preferred surgical management for complex, unreconstructable radial head fractures. There has been increasing use of pyrocarbon prostheses, with potential tribology and modulus advantages over metallic counterparts. This study aims to assess clinical and radiological outcomes for radial head replacement after trauma using a modular, uncemented pyrocarbon prosthesis.

Materials and Methods

Between September 2009 and March 2020, a consecutive series of 22 trauma cases were available for review. Patients underwent radial head arthroplasty using a pyrocarbon prosthesis (Ascension Modular Radial Head System, Austin, TX). Recorded outcomes included clinical assessment, radiological evaluation, and patient-reported outcome measures specific to elbow function.

Results

Twenty-two patients (7 male, 15 female) with an average age of 51 years (range 21-64) were analyzed with a minimum 12 months of follow-up. All patients had complex radial head fractures, categorized as a Mason 3 or 4 injury. At follow-up, mean elbow range of motion included flexion 130° (range 100°-150°), extension 19° (0-50°), pronation 73° (30°-90°), and supination 70° (10°-90°). The mean Mayo Elbow Performance Index score was 83 (55-100), and Disabilities of the Arm, Shoulder and Hand score was 22 (2.5-60). Radiological evaluation showed 14 patients with asymptomatic proximal neck resorption and two patients with radiological stem loosening. In total, 3 of 22 implants were revised-2 were excised, and 1 revised to a long stem for traumatic implant fracture.

Conclusion

Pyrocarbon radial head arthroplasty provided reliable functional results for patients after unreconstructable radial head fracture. The unique potential for fracture of the prosthesis should be considered in long-term follow-up, with appropriate activity advice to patients.

Short- to mid-term outcomes of radial head replacement for complex radial head fractures

Background

The purpose of the current study was to investigate short- to mid-term outcomes and complications following radial head replacement (RHR) for complex radial head fractures and to identify factors associated with clinical outcomes.

Methods

Twenty-four patients with complex radial head fractures were treated by RHR. The mean age of the patients was 49.8 years (range, 19–73 years). Clinical and radiographic outcomes were evaluated for a mean follow-up period of 58.9 months (range, 27–163 months) using the visual analog scale (VAS) score for pain, the Mayo elbow performance score (MEPS), the quick disabilities of the arm, shoulder and hand (Quick-DASH) score, and serial plain radiographs. Complications were also evaluated.

Results

At the final follow-up, the mean VAS score, MEPS, and Quick-DASH score were 0.6±1.1, 88.7±11.5, and 19.4±7.8, respectively. The mean range of motion was 132.7° of flexion, 4.7° of extension, 76.2° of pronation, and 77.5° of supination. Periprosthetic lucency was observed in six patients (25%). Heterotopic ossification was observed in four patients (16.7%). Arthritic change of the elbow joint developed in seven patients (29.2%). Capitellar wear was found in five patients (20.8%). Arthritic change of the elbow joint was significantly correlated with MEPS (P=0.047). Four cases of complications (16.6%) were observed, including two cases of major complications (one stiffness with heterotopic ossification and progressive ulnar neuropathy and one stiffness) and two cases of minor complications (two transient ulnar neuropathy).

Conclusions

RHR for the treatment of complex radial head fractures yielded satisfactory short- to mid-term clinical outcomes, though radiographic complications were relatively high.

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.

Acute radial head replacement with bipolar prostheses: midterm results

In irreparable radial head fractures, especially if primary stabilizers of the elbow are damaged, the prosthetic replacement prevents instability and stiffness. Concerns have arisen over the use of bipolar press-fit prostheses due to the frequent finding of osteolysis and the risk of instability if compared to monopolar implants. Our aim was to assess midterm clinical and radiological outcomes of bipolar implants and the influence of osteolysis on proximal pain. Seventeen patients with irreparable fractures of the radial head, treated in acute with the same prosthetic model (rHEAD recon SBI/Stryker) between January 2015 and December 2018, were enrolled. Clinical assessment was performed using MEPS and DASH scores; a radiographic study was done to identify heterotopic ossifications and periprosthetic osteolysis. Outcomes at the last follow-up, according to MEPS, were excellent in 10 cases, good in 5 and fair in 2; none of the patients had severe pain or instability. In 3 cases, it was necessary to remove the implant, mainly because of early loosening. Radiological findings of osteolysis were detected in 9 cases, but no statistical correlation was found with MEPS and proximal pain. The use of bipolar implants is reliable if an accurate repair of ligament tears is performed and provides a good stability. Nevertheless, the risk of early aseptic loosening in uncemented implants is not negligible, and the follow-up of the patient must be strict. Late osteolysis does not seem to have clinical relevance, but further prospective studies are necessary to clarify this topic.

Correlation between radiographic findings and clinical failure in monopolar radial head replacement

INTRODUCTION

The purpose of this study is to analyze the mid-term outcomes of a modular monopolar type of radial head arthroplasty in the treatment of complex fractures associated with acute elbow joint instability. We postulated that radiographic changes are related to the development of clinical complications.

MATERIALS AND METHODS

We evaluated at last follow-up 26 radial head arthroplasties in 26 consecutive patients who were followed for at least one and a half year. All patients had suffered radial head fractures (Mason III) in the context of unstable elbow injuries. Definitive treatment of the radial fracture was performed with modular and monopolar prosthesis which was inserted as a press fit. All patients were evaluated preoperatively and postoperatively. The evaluation included a clinical examination and a protocolized imaging study (standard X-Rays and CT) of the elbow. We analyzed the incidence of: heterotopic ossifications, secondary radiocapitellar joint osteoarthritis, hardware loosening, hardware disengagement, and joint infection. Diagnosis of clinical failure of the implant was defined as the time to the second surgery due to major complications related to the prosthesis, such as persistent lateral side pain or elbow stiffness and any kind of implant instability or dislocation.

RESULTS

The implant-specific reoperation rate was 15% (four reoperations). The need for the second surgery was statistically associated with heterotopic ossifications, radiocapitellar osteoarthritis and cortical resorption around radial neck (p = 0.054, p = 0.033, and p = 0.019, respectively), being periprosthetic osteolysis the most likely factor related to failure, and radial pain the main symptom leading to surgical revision.

CONCLUSIONS

Our study shows a positive association between radiographic findings and patient symptoms for postoperative complications after radial head arthroplasty. Failed radial head replacements may lead to reoperation mainly due to pain, and this can be distinguished from other causes of pain in elbow region based on its radial location. Radiological loosening was prevalent in this group of failed replacement.

Stem Length and Neck Resection on Fixation Strength of Press-Fit Radial Head Prosthesis: An In Vitro Model

PURPOSE

Various radial head prosthesis designs are currently in use. Few studies compare different prosthetic designs. We hypothesized that increasing a cementless implant stem's length would reduce stem-bone micromotion, with both short and long neck cuts. We also hypothesized that a minimum stem length might be required for the initial fixation strength of a press-fit implant.

METHODS

In 16 fresh-frozen cadaveric elbows (8 pairs), the radial head and neck were cut either 10 or 21 mm below the top of the head. Modular cementless stems were inserted and sequentially lengthened in 5-mm increments. Micromotion under eccentric loading was tested after each incremental change.

RESULTS

Incremental lengthening of the prosthetic stem and the amount of neck resection (10-mm cut vs 21-mm cut) both had a significant effect on micromotion. After a 10-mm radial head-neck resection, we observed a significant decrease in micromotion with stem lengths of 25 mm or greater, whereas with 21 mm of neck resection there was no further reduction in micromotion with increased stem length. These differences can be explained, at least in part, by the concept of the cantilever quotient: the ratio of the head-neck length outside the bone to the total length of the implant.

CONCLUSIONS

The length of the stem affects the initial stability of press-fit radial head prostheses when the level of head and neck resection is at the minimum (ie, 10 mm) for currently available prosthetic designs. At this resection level, stems 25 mm or greater had significantly higher initial stability, but all stem lengths tested had mean micromotion values within the threshold for bone ingrowth.

CLINICAL RELEVANCE

The length of a radial head prosthetic stem affects the initial stability of press-fit radial head prostheses when the level of head and neck resection is at the minimum (ie, 10 mm) for currently available prosthetic designs.

Metallic Press-fit Radial Head Replacement for Radial Head Fractures

This study evaluated the clinical and radiographic results of patients who sustained nonreconstructible radial head fractures that subsequently were treated with a metallic press-fit radial head prosthesis (RHP). Nine patients with comminuted radial head fractures were treated with a metallic press-fit RHP; mean follow-up was 38.7 months. The radial head fracture was acute in 6 patients (group A) and chronic in 3 patients (group B). Functional evaluation was assessed using the Mayo Elbow Performance Score (MEPS) and Disabilities of the Arm, Shoulder and Hand (DASH) Questionnaire. Radiographs were assessed for loosening, radiocapitellar alignment, osteolysis of the radial neck, lucency, periarticular ossifications, and ulnohumeral degeneration. Average flexion and flexion contracture were 133° and 5°, respectively. Average supination and pronation angles were 70° and 73°, respectively. Mean MEPS was 90 (range, 70-100), and elbow performance was excellent in 4 patients, good in 4 patients, and fair in 1 patient. Mean DASH score was 21.9 (range, 0-61). Flexion contracture, forearm rotation arc, and MEPS score were better and the complication rate was lower in group A compared with group B. Centering of the stem was observed on both anteroposterior and lateral radiographs in 6 patients. Lucent lines around the prostheses, stress shielding under the neck of the radius, and ectopic ossification occurred in 5 patients. Three patients had osteoarthritis. Elbow stiffness and ulnar impaction syndrome occurred in 2 patients but only after placement of a secondary RHP. Satisfactory outcomes were obtained using a metallic press-fit RHP for nonreconstructible radial head fractures. [Orthopedics. 2019; 42(6):e545-e551.].

Pyrocarbon arthroplasty in acute unreconstructable radial head fractures: mid-term to long term results

BACKGROUND

The aim of this study is to describe the mid-term radiological findings appearing in patients with a pyrocarbon radial head prosthesis, and to correlate them to patient symptoms.

MATERIALS AND METHODS

We review 18 patients who underwent radial head implantation of the MoPyC prosthesis between 2004 and 2015, due to unreconstructible radial head fractures. The clinical outcomes were assessed with Mayo Elbow Performance Score (MEPS). Range of motion, pain, and elbow radiological assessments were recorded. A non-parametric, statistical analysis was carried out to assess the radiological findings with the clinical outcomes.

RESULTS

We have found that after a mean follow-up of 6.5 years (2-11 years), patients have recovered a median flexion arch of 113°, therefore 77% are classed as satisfactory outcomes and the average MEPS score is 89.5. The presence of periprosthetic changes on X-ray is highly frequent-we found radiolucent lines in 38% of cases, radial neck re-absorption in 83%, and arthrosic changes in 78%. However, the differences found when correlating these changes with the clinical results have not been statistically significant (p > 0.05).

CONCLUSIONS

Satisfactory outcomes can be expected midterm when using pyrocarbon prostheses in around 75% of the cases. We consider radial neck re-absorption to be a sign of good stem osteointegration, whereas progressive radiolucencies and loss of the ballooning of the stem legs are signs of bad prognosis in our series.

LEVEL OF EVIDENCE

IV retrospective case series.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Radial head replacement with a bipolar system: an average 10-year follow-up

BACKGROUND

We report the long-term results of a cohort of patients after radial head replacement with a bipolar design and a smooth cementless stem at a mean follow-up of 10.4 years.

METHODS

Of 17 possible patients from a previous minimum 2-year follow-up study, 16 were available for review. Patients were assessed using clinical and radiographic examination and with standardized outcome measures. Range of motion, stability, and radiographic evaluation of implant loosening and joint degeneration were assessed. Comparisons were performed using the Wilcoxon signed rank test for unequal groups.

RESULTS

The average follow-up was 10.5 years (range, 8.5-12 years). The median visual analog scale was 1 (range, 0-5), Minnesota Elbow Performance Index was 93 (range, 70-100), and the Disabilities of the Arm, Shoulder and Hand was 7.5 (range, 0-53). Range of motion was decreased on the operative side compared with the nonoperative side for flexion/extension (P = .005) and pronation/supination (P = .015). Grip strength was decreased on the affected side (P = .045). No patients had elbow instability. Significant arthritic changes developed in 2 patients at the ulnohumeral joint. The median cantilever quotient was 0.4 (range, 0.30-0.50). Osteolysis in zones 1 to 7 was found in all but 2 patients. The median stem radiolucency was 0.5 mm (range, 0.2-0.9 mm). No reoperations occurred since our previous report. Implant survival in this cohort was 97%.

CONCLUSION

Bipolar radial head prosthesis with a smooth cementless stem effectively restores elbow stability and function after comminuted radial head fractures with or without concomitant elbow instability. Our study demonstrates excellent long-term implant survival.

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.

Radial Head Ingrowth Anatomic Implant Versus Smooth Stem Monoblock Implant in Acute Terrible Triad Injury: A Prospective Comparative Study

OBJECTIVE

This study aimed to compare clinical outcomes and radiographic findings between patients who received 2 different implants (smooth-stemmed modular implant or an anatomic press-fit implant) on patients with acute terrible triad injuries.

DESIGN

Prospective cohort.

SETTING

Level II Trauma center, University hospital.

PATIENTS/PARTICIPANTS

Thirty-four patients with an isolated terrible triad injury were divided into 2 study groups (n = 17 each) with different sets of radial head implants and followed for 2 years. A total of 14 patients in each group (n = 28) completed the study.

INTERVENTION

Group 1 received a smooth-stemmed round modular monopolar implant. Group 2 received an in-growth modular monopolar press-fit anatomic implant.

MAIN OUTCOME MEASUREMENTS

Clinical outcomes were evaluated using the Visual Analog Scale, Mayo Index, and Disabilities of the Arm, Shoulder, and Hand (DASH) survey. Radiographs were evaluated for ectopic bone formation and loosening.

RESULTS

No difference in clinical outcome when comparing range of motion and functionally scores between groups. Ectopic bone formation occurred equally with implants. Bone formation at the proximal radius under the implant occurred more in group 1 (85.7%), (P = 0.046). Five press-fit stems had radiolucent lines at 2-year follow-up. Two were removed because of symptomatic loosening.

CONCLUSIONS

Short-term outcomes for both implants showed to be equally effective treatment options. The in vitro biomechanical advantages of anatomic implants do not translate into short-term improved outcomes. Symptomatic aseptic loosening in anatomic implants is common. Bone formation at the proximal radial neck was observed more with smooth-stemmed implants; further studies should assess this findings and clinical implication.

LEVEL OF EVIDENCE

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

Radial Head Arthroplasty in the Active Duty Military Service Member With Minimum 2-Year Follow-Up

PURPOSE

Radial head arthroplasty (RHA) is a viable treatment for complex radial head fracture. Whereas elbow stability and function is typically restored at short- to mid-term follow-up, the outcome in higher-demand populations is not well defined. We sought to characterize the functional and occupational outcomes following RHA in an active duty military population with intense upper extremity demands.

METHODS

We retrospectively reviewed the records of all U.S. military service members undergoing primary RHA from 2010 and 2013 with a minimum of 2-year follow-up. Patient-based, injury-related, and surgical variables were extracted from the military-wide electronic medical record. Functional and occupational outcomes including pain, and Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire were recorded. The primary outcomes of interest were the rate and level of return to upper extremity activity. Secondary outcome measures included return to duty, complications, and revision surgery.

RESULTS

Nineteen patients were included with average age 31 years and median 37 months' follow-up. Ten were Mason III, 6 were part of a terrible triad injury, and the remainder were fracture-dislocations. At an average follow-up of 3.7 years, 15 patients returned to active military duty, and 9 resumed their regular upper extremity military function. At the time of final follow-up, the average DASH score was 13. Seven patients returned to their usual level of sport and exercise, 6 at a reduced level, and 6 did not resume physical exercises secondary to pain or stiffness. Sixteen adverse outcomes among 14 patients included symptomatic heterotopic ossification (5 of 19) and neurological sequelae (4 of 19). Three elected to have a revision procedure at an average of 13 months for heterotopic ossification or loosening.

CONCLUSIONS

Among active patients with radial head fractures treated with RHA, three-quarters will return to active duty military service, push-ups, and sport; however, half may report an adverse outcome unrelated to the prosthesis and only about half of patients will return to their preinjury level of function.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

[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.

Outcomes and radiographic findings of anatomic press-fit radial head arthroplasty

BACKGROUND

Radial head arthroplasty (RHA) is a popular method of treatment for complex fractures of the radial head. The purpose of this study was to investigate patient outcomes and radiographic findings associated with a single anatomic monopolar press-fit radial head system commonly used for the treatment of radial head fractures.

METHODS

A retrospective review of prospectively collected data was performed for a consecutive series of patients treated with a press-fit anatomically designed RHA between November 2007 and April 2014. The most recent radiographs were evaluated for loosening, stress shielding, and instability. Postoperative motion and outcomes were reported at most recent follow-up.

RESULTS

At an average follow-up of 30 months, 6 of the 15 patients (40%) demonstrated radiographic loosening. Six of the 9 patients (67%) without loosening demonstrated stress shielding (average, 6 mm). Functional outcome scores included a mean American Shoulder and Elbow Surgeons score of 70, Mayo Elbow Performance Score of 85, visual analog scale score for pain of 2, visual analog scale score for function of 7, and Single Assessment Numeric Evaluation score of 75. Average flexion-extension arc was 14° to 138°, and average pronation-supination was 75° to 74°. All 6 of the patients with radiographic loosening had undergone RHA with an associated ligamentous injury repair. Satisfaction among patients was high as no patient reported an unsatisfactory outcome.

CONCLUSIONS

The use of an anatomic, press-fit monopolar RHA in the management of acute complex radial head fractures has yielded excellent clinical outcomes despite high rates of radiographic loosening and stress shielding. Press-fit RHA in the setting of ligamentous injury warrants further investigation because of a high rate of implant loosening observed.

Radial head arthroplasty: state of the art

Radial head arthroplasty has joined the armamentarium of options for the treatment of complex radial head fractures, elbow instability, and arthritic conditions. A variety of implants has been introduced in the past decade; these differ in metallic composition, design, and method of fixation. Good short- and intermediate-term outcomes have been reported with the use of loose-fitting prostheses. Press-fit devices restore stability and improve pain and motion but are associated with a greater likelihood of implant loosening, leading to revision surgery. Postoperative elbow stiffness, pain, ulnar nerve palsy, posterior interosseous nerve palsy, and heterotopic ossification have all been reported following radial head surgery, but these complications are likely related to the trauma sustained by the elbow. Adequate knowledge of the surgical indications, types of implants, and surgical technique are essential for a satisfactory outcome when a radial head prosthesis is used for the treatment of nonreconstructable radial head fractures.

Radial head, radiocapitellar and total elbow arthroplasties: a review of recent literature

The outcome of prosthetic elbow surgery is continually evolving. We thoroughly reviewed the literature on this issue to analyse the indications, outcomes and complications of the numerous types of implants currently in use. Radial head replacement is recommended in comminuted fractures of the radial head and in post-traumatic conditions. Medium- and long-term results prove to be satisfactory in the majority of cases, with no evidence to indicate that some prostheses (monopolar vs. bipolar; cemented vs. press-fit) are more effective than others; nonetheless, the bipolar-cemented implant was found to be associated with a lower revision rate than other prostheses. Unicompartmental arthroplasty has recently been used for the treatment of osteoarthritis and rheumatoid arthritis when the lateral compartment is prevalently involved; the results reported to date have been encouraging, although further studies are warranted to confirm the validity of these implants. Total elbow arthroplasty is performed in a range of conditions, including distal humerus fractures in the elderly and elbow arthritis. In the former condition, linked elbow replacement yields excellent results with few complications and a low revision rate. In elbow arthritis, total elbow arthroplasty is indicated when patients suffer from disabling pain, stiffness and/or instability that prevent them from performing daily activities. Unlinked elbow arthroplasty, which is used above all in rheumatoid arthritis, also yields satisfactory results, although the risk of instability persists. The use of linked elbow arthroplasty, which yields similar results but lower revision rates, has consequently increased. Lastly, the results yielded by linked elbow prosthesis in post-traumatic conditions are good, although not quite as good as those obtained in rheumatoid arthritis. Early mechanical failure may occur in younger and more active patients after elbow arthroplasty. However, the careful selection of patients who are prepared to accept functional limitations imposed by elbow implants will enable indications for elbow arthroplasty to be extended to young subjects, particularly when no other therapeutic options are available.

Clinical and radiographic comparisons of two different radial head implant designs

BACKGROUND

There is little comparative data to guide implant choice for radial head replacements. The purpose of this study was to evaluate the clinical and radiographic results between patients who received a smooth-stemmed bipolar radial head implant and patients who received an in-growth monopolar prosthesis.

METHODS

Twenty-seven patients requiring a metallic radial head implant in the management of acute or chronic elbow trauma were evaluated. Fourteen patients received a smooth-stemmed bipolar prosthesis and 13 patients received a press-fit monopolar prosthesis. Patients returned for follow-up at an average of 33 months (range, 18-57). Outcome assessments included joint motion, elbow stability, grip strength, pain, the Mayo Elbow Performance Index, and the Disability of Arm, Shoulder and Hand questionnaire. Radiographs were reviewed for joint congruence, ectopic bone, periprosthetic osteolysis, degenerative arthritis, and capitellar wear, and selected patients were tested for inflammatory markers and metal ion levels.

RESULTS

The differences between patient groups for elbow flexion and forearm pronation averaged 10° or less. There were no other pertinent differences between groups for standardized patient and examiner-determined outcomes. There was a trend for ectopic bone to develop more commonly around the smooth-stemmed implants, while periprosthetic osteolysis was more pronounced in cases with the press-fit design. Inflammatory markers were normal, and metal ion levels did not exceed values reported for a well-functioning hip arthroplasty.

CONCLUSION

Outcomes at short- to mid-term follow-up were similar with either implant design. Loosening of a press-fit prosthesis may lead to extensive osteolysis, but of undetermined clinical consequence.

Radial head arthroplasty: a radiologic outcome study

OBJECTIVE

The purpose of this study is to provide a radiographic outcome assessment of radial head arthroplasty in correlation with clinical outcomes and to determine whether there is an association between certain patient factors and clinical and radiographic outcomes.

MATERIALS AND METHODS

A 10-year retrospective review was performed to identify patients with metal radial head arthroplasty. At least two follow-up radiographs were reviewed for each patient and were correlated with clinical information. Statistical analysis included calculation of complication rates, phi coefficient for variable association with complications, and Kaplan-Meier survival.

RESULTS

A total of 258 radial head implants in 244 patients were reviewed. The mean patient age was 46 years, with mean follow-up time of 12.8 months. Two hundred nineteen (84.9%) implants were unipolar in design, whereas 39 implants were bipolar. The most common indication for arthroplasty was trauma (94% acute and 2% failed internal fixation). Radiographic abnormalities included nonbridging heterotopic ossification (38.0%), secondary radiocapitellar joint osteoarthritis (27.9%), loosening (19.8%), bridging heterotopic ossification (8.9%), fracture (2.3%), and hardware dislocation (2.7%). Overall, there were 62 second surgeries for either revision or removal. Reasons for second surgery included heterotopic ossification (53.2%), synovectomy or capsulectomy (43.5%), and infection (3.2%). There was a statistically significant association between radiographic complications and the presence of patient symptoms (p < 0.05). There was no association between radiographic or clinical complications with age, sex, side, or type of arthroplasty (R < 0.001).

CONCLUSION

There is a positive association between radiographic findings and patient symptoms for postoperative complications after radial head arthroplasty. By 9 months, 50% of implants showed radiographic complications.

Radial head fractures

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

Short- to mid-term results of metallic press-fit radial head arthroplasty in unstable injuries of the elbow

We assessed the short- to mid-term survival of metallic press-fit radial head prostheses in patients with radial head fractures and acute traumatic instability of the elbow.

The medical records of 42 patients (16 males, 26 females) with a mean age of 56 years (23 to 85) with acute unstable elbow injuries, including a fracture of the radial head requiring metallic replacement of the radial head, were reviewed retrospectively. Survival of the prosthesis was assessed from the radiographs of 37 patients after a mean follow-up of 50 months (12 to 107). The functional results of 31 patients were assessed using range-of-movement, Mayo elbow performance score (MEPS), Disabilities of the Arm, Shoulder and Hand (DASH) score and the RAND 36-item health survey.

At the most recent follow-up 25 prostheses were still well fixed, nine had been removed because of loosening, and three remained implanted but were loose. The mean time from implantation to loosening was 11 months (2 to 24). Radiolucent lines that developed around the prosthesis before removal were mild in three patients, moderate in one and severe in five. Range of movement parameters and mass grip strength were significantly lower in the affected elbow than in the unaffected side. The mean MEPS score was 86 (40 to 100) and the mean DASH score was 23 (0 to 81). According to RAND-36 scores, patients had more pain and lower physical function scores than normal population values.

Loosening of press-fit radial head prostheses is common, occurs early, often leads to severe osteolysis of the proximal radius, and commonly requires removal of the prosthesis.

Alteration of the end-plane angle in press-fit cylindrical stem radial head prosthesis: an in vitro study

PURPOSE

Many studies comparing the morphology of native radial head with the prosthesis have been published. However, there is limited information regarding the postoperative alignment of the articular surface following the radial head replacement. The purpose of this study is to evaluate the alteration of the end-plane angle in the modular radial head prosthesis with a press-fit cementless cylindrical stem.

METHODS

The study used 36 cadaveric radii. The press-fit size prosthesis with cylindrical stem was inserted into each specimen. The end-plane angles of the radial head before and after prosthetic replacement, were measured in coronal and sagittal planes with a digital inclinometer. The data were analyzed by paired t-test.

RESULTS

From paired t-test, there were statistically symmetrical end-plane angles before and after radial head replacement in both coronal and sagittal planes (p-value < 0.01). The mean of radial head end-plane angle alteration in the coronal plane was 3.62° (SD, 2.76°) (range, 0.3°-8.9°). In the sagittal plane, the mean of alteration was 5.85° (SD, 3.56°) degrees (range, 0.3° - 14.2°).

CONCLUSION

The modular radial head prosthesis with cylindrical stem is in vitro able to restore the native end-plane angles of radial heads statistically when used in a press-fit fashion.

Forearm pain associated with loose radial head prostheses

BACKGROUND

After post-traumatic radial head replacement, pain caused by a loose prosthesis might incorrectly be assumed to be post-traumatic. Reliable guidelines for diagnosing a symptomatic loose radial head prosthesis are lacking. We noted that pain from a loose stem within the proximal radius may present as proximal radial forearm pain.

METHODS

The medical records and radiographs of 14 consecutive cases (13 patients) with proximal radial forearm pain associated with a loose radial head prosthesis were reviewed retrospectively. The indication for revision surgery was painful loosening of the prosthesis within the canal of the proximal radius in 7 patients (8 cases) and pain without preoperative confirmation of the loosening in 2 patients (2 cases). Various prosthetic designs had been used in the primary operations.

RESULTS

In 12 of 14 cases, the loosening was evident radiographically, but in 2 the only indication of a loose prosthesis (confirmed surgically) was proximal radial forearm pain. One patient was lost to follow-up. Revision or prosthetic removal eliminated the pain in 7 of 9 cases and decreased it in 1. One patient with moderate pain had an arthritic elbow and had no significant lasting relief from surgery. Follow-up averaged 27 months.

CONCLUSION

The presence of proximal radial forearm pain in a patient with a radial head prosthesis is an indicator of symptomatic mechanical loosening. If the prosthesis has a textured surface for bone ingrowth, and was inserted without cement, we now consider this a strong indicator of loosening, even in the absence of radiographic signs.

Mid- to long-term results after bipolar radial head arthroplasty

BACKGROUND

Radial head arthroplasty is considered the treatment of choice for unreconstructable radial head fractures in the acute fracture situation. Although short-term results in the current literature are promising, replacement of the radial head remains controversial as long-term results are still missing. We report our 8.8-year results after treatment with a bipolar radial head prosthesis by Judet.

MATERIALS AND METHODS

In our department, 19 patients were treated with bipolar radial head arthroplasty between 1997 and 2001. Seventeen of these patients-14 men and 3 women-were examined retrospectively after 106 months (range, 78-139). Of these, 9 patients were treated primarily, 7 patients secondarily, and 1 because of a tumor.

RESULTS

On the Mayo Elbow Performance Score, 6 patients achieved excellent results, 10 good, and one fair. The mean DASH score was 9.8 (range, 0-34). No differences were seen between primary and secondary implantation. Flexion averaged 124° (range, 110-150°), the extension deficit was 21° (range, 0-40°), pronation 64° (range, 30-90°), and supination 64° (range, 30-90°). The following complications were seen: 2 dislocations and 8 cases of degenerative changes of the capitellum, 1 with severe erosion. Signs of ulnohumeral arthrosis were found in 12 patients. No evidence of loosening, radiolucencies, or proximal bone resorption was detected.

CONCLUSION

Despite major primary complications and high incidence of radiographic signs of degenerative changes after 8.8 years, mainly good clinical results were achieved with Judet's bipolar prosthesis.

Cementless fixation of radial head implants is affected by implant stem geometry: an in vitro study

BACKGROUND

Metal radial head implants are widely used for the management of unreconstructible fractures. However, the effect of implant stem design on initial fixation and stability is unknown. This study determined the effects of radial head stem geometry on the initial stability of the uncemented implant. It was hypothesized that cortical contact and hence increased fixation would be achieved with an increased stem diameter, stem length and a tapered shape.

METHODS

Eleven radii received five implants with differing stem geometries: short and long undersized, short and long optimally sized and short tapered. Inferiorly-directed compressive loads were applied successively to the anterior, posterior, medial and lateral edges of the implants. Maximum contralateral radial head "lift-off" was quantified by the distance between bone and implant surface markers.

FINDINGS

The short and long undersized implants experienced greater micromotion with approximately 100 microm and 160 microm more lift-off respectively (P<0.02). The remaining optimally sized and tapered implants averaged 50 microm. There was greater motion for the undersized implants loaded at the lateral position (P0.005).

INTERPRETATION

This study shows that filling the diameter of the medullary canal is more important than filling the length of the canal. The taper did not offer any additional advantages compared to the straight stem, suggesting that reaming of bone to accept the taper did not produce enhanced initial purchase. If rigid initial implant fixation is desired with an uncemented radial head implant, a canal-filling stem reduces initial implant micromotion to less than 50 microm which may enhance bone ingrowth.