Radial head arthroplasty diameter impact on elbow kinematics evaluated by dynamic radiostereometric analysis.

Purpose: Radial head arthroplasty (RHA) reestablishes elbow stability after complex radial head fracture, but complication rates are high, possibly due to inappropriate implant sizing. Knowledge of impact of radial head implant diameter on elbow kinematics is limited and warranted. This study evaluated elbow kinematics of different radial head implant diameters after RHA using dynamic radiostereometric analysis (dRSA). Methods: Eight human donor arms were examined with dRSA during elbow flexion with the forearm in unloaded neutral position, and in supinated- and pronated position without and with 10N either varus or valgus load, respectively. Elbow kinematics were examined before and after RHA with head diameters of anatomical size, -2 mm (undersized), and +2 mm (oversized). The ligaments were kept intact by use of step-cut humerus osteotomy for repeated RHA exchange. Bone models were obtained from CT, and by AutoRSA software bone models were matched with dRSA recordings. The elbow kinematics were described using anatomical coordinate systems. Results: Compared to the native radial head during elbow flexion, the anatomical sized RHA shifted 2.0 mm in ulnar direction during unloaded pronated forearm position. The undersized RHA shifted 1.5 mm in posterior direction and 2.1 mm in ulnar direction during unloaded pronated forearm position and increased the varus angle by 2.4° during supinated loaded forearm position. The oversized RHA shifted 1.6 mm in radial direction during loaded supinated forearm position. Conclusions: The anatomically sized RHA should be preferred as it maintained native elbow kinematics the best. The kinematic changes with oversized and undersized RHA diameters were small, suggesting forgiveness for the RHA diameter size. Level of Evidence: Level III.

Long Title: Short to Midterm Outcomes of 139 Pyrocarbon Monopolar Radial Arthroplasties.

INTRODUCTION: 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 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 (quickDASH) score, visual analog scale (VAS), radiographic outcome, and reason for failure were recorded. RESULTS: The mean MEP, QuickDASH, 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 (OAS) were identified in 92(66%) and 20(14%) patients. A total of 47(29%) patients experienced at least one 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<0.05). Stress shielding (SS) was associated with an increase in MEPS (aß=6.92; p<0.001) and lower VAS (aß=-0.69; p=0.016). The auto-expending stem increased the likelihood of SS after RHA (aOR=1.49; p=0.001). 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.

Arthroscopic matched osteoplasty of the radial head for painful radiocapitellar osteoarthritis: surgical technique and case series.

Background: Radiocapitellar arthritis can cause pain, loss of motion, and impaired elbow function. Current surgical treatment options are limited. We have developed an original and simple surgical technique to address this, called arthroscopic matched osteoplasty of the radial head (AMOR). In AMOR, the radial head is partially resected and recontoured to match the capitellum and decompress the degenerate radiocapitellar articulation while preserving the ulnohumeral articulation where the cartilage is usually well preserved. Methods: Indications and the surgical technique of the AMOR procedure are described. A retrospective observational service evaluation study was conducted from electronic patient records. Collected clinical outcomes included range of motion, pain level, subjective functional score, and general satisfaction with the results of the procedure. The radiographic outcome was radiocapitellar joint space. Results: Between 2017 and 2021, eight consecutive patients underwent AMOR as part of an arthroscopic osteocapsular arthroplasty procedure. Radiographically, the mean radiocapitellar joint space improved from an average of 1.7 mm to 4.6 mm. Clinically, the mean pain score decreased from 8/10 to 3/10. Six of the eight patients (75%) were satisfied with their results. In two cases, initial improvement following surgery lasted less than 1 year, and one of these patients underwent total elbow arthroplasty for painful ulnohumeral osteoarthritis. There were no complications of surgery recorded. Conclusions: AMOR is a safe treatment option for painful radiocapitellar osteoarthritis and can be incorporated as an "add-on" procedure by surgeons performing elbow osteocapsular arthroplasty. Level of evidence: IV.

A Systematic Review and Network Meta-Analysis of Randomised Controlled Trials Comparing Treatments for Displaced Radial Head Fractures.

Background: The aim of this study is to compare the surgical and non-operative management of displaced radial head fractures via a network meta-analysis of randomised controlled trials (RCTs). Methods: RCTs comparing management of isolated, displaced radial head fractures in adults were included in our review and statistical analysis. A systematic review of electronic databases (Medline, Embase and Cochrane Library) were screened for comparative RCTs reporting on the management of displaced radial head fractures in August 2021. Two investigators independently reviewed studies for eligibility and an assessment of bias was performed for each study. A Bayesian network meta-analysis of the included RCTs was performed. Results: Five RCTs (326 patients) were included in our meta-analysis. Treatment methods included radial head arthroplasty (RHA), open reduction internal fixation (ORIF) with metal implants (ORIF-M), ORIF with biodegradable implants (ORIF-B) and non-operative management. In our network meta-analysis of 'good' or 'excellent' patient-reported outcome measures (PROMs), RHA was significantly favourable to ORIF-M (OR: 0.04, CrI: 0.0011, 0.87), ORIF-B (OR: 0.1 CrI: 0.00076, 6.37). Nonoperative treatment was not shown to be significantly worse than RHA (OR: 0.01 CrI: 2.5e-0.5, 3.61). Conclusions: This network meta-analysis shows that in displaced radial head fractures, RHA is associated with significantly superior functional PROMs than ORIF-M based on the evidence available. Nonoperative management has not been shown to be significantly worse. Level of Evidence: Level III (Therapeutic).

Radiocapitellar joint plasty for missed monteggia fracture with radial head deformity in children: a retrospective study.

Purpose: The retrospective study reviewed the clinical and radiological outcomes of patients treated with radiocapitellar joint plasty. Methods: 10 children with missed Monteggia fracture (MMF) were reviewed. The average time from injury to operation was 20 months. The average age of children who underwent the operation was 10.5 years. 6 flat and 4 domed radial heads were included. 7 type I and 3 type III MMF were identified based on the Bado classification. All children with MMF were treated by open radial head reduction with radiocapitellar joint plasty and ulnar osteotomy (UO). Results: The average union time was 4.9 ± 2.6 months. The average osteotomy angle to reduce the radial head was 15.7 ± 3.5°, and the average lengthening of the ulna was 8.2 ± 3.2 mm. The average preoperative flexion range of motion was 110.5 ± 9.1°, and the postoperative flexion range of motion was 138.8 ± 15.1° (p < 0.05). The average preoperative extension range of motion was 10.1 ± 3.2°, and the postoperative extension range of motion was 5.5 ± 3.3° (p < 0.05). The average preoperative pronation range of motion was 78.8 ± 8.7°, while the postoperative pronation range of motion was 81.1 ± 5.6° (p > 0.05). The average preoperative supination range of motion was 68.3 ± 9.7°, and the postoperative supination range of motion was 80.1 ± 7.8° (p < 0.05). The preoperative Kim score was 66.5 ± 10.9°, and the postoperative Kim score was 88.1 ± 12.6 (p < 0.05). The radial head was completely reduced in 9 patients, and subluxation in 1 patient. Osteoarthritis of the radiocapitellar joint was observed in 2 patients. Conclusions: Radiocapitellar joint plasty is effective surgical intervention for MMF with radial head deformity. It yields favorable functional outcomes while ensuring continued radial head reduction.

Proximal radial neck fracture with complete 180-degree rotation of radial head: A case report.

Radial neck fractures with radial head rotation are very rare and extremely difficult to manage. We present the case of an 11-year-old girl who fell on her outstretched left upper extremity and damaged her left elbow in a road traffic accident. An arthrotomy was performed under a C-Arm fluoroscope, which confirmed the radial head displacement of 180° along with the fracture. The fracture site was reduced and fixed with two Kirschner wires, cutting the wire short at its distal end for a complete closure. Open reduction and internal fixation were followed by casting for five weeks. After two years of follow-up, she had complete pain free range of motion of the affected limb. No post-operative complications have been observed till date. Open reduction and internal fixation with two Kwires is a viable option for such complex injuries. However, further evaluation of outcomes and post-operative complications are required.

Microstructure of the radial head: Insights into anatomical variations and implications for advanced interventions.

Appropriate management of radial head fractures is integral to prevent long-term consequences like chronic pain and loss of motion. Advanced imaging systems, like micro-computed tomography (µCT), are valuable for understanding radial head fracture patterns as they utilize micrometer scale resolution to define important parameters of bone health like cortical density and trabecular thickness. The purpose of this study was to identify and describe the structural morphology of the radial head utilizing µCT. Nine fresh-frozen cadaveric human radii were divided into four equal quadrants, based, and labeled as posteromedial, posterolateral, anteromedial, and anterolateral. Quadrants were scanned with a SCANCO MicroCT40 with both cortical and cancellous bone density measurements at a resolution of 36.0 µm. Bone density, direct trabecular number, and trabecular thickness were recorded as milligrams of hydroxyapatite/cm3. A one-way repeated measures ANOVA was performed to compare the bone densities, trabecular number, and trabecular thickness of each of the four quadrants (p < 0.05). The posteromedial quadrant contained substantially more bone than other quadrants. Significantly greater bone densities were found in the posteromedial quadrant (148.1 mg of HA/cm3) compared to the anteromedial quadrant (54.6 mg of HA/cm3), posterolateral quadrant (137.5 mg of HA/cm3) compared to the anteromedial quadrant (54.6 mg of HA/cm3), and posterolateral quadrant (137.5 mg of HA/cm3) compared to the anterolateral quadrant (58.1 mg of HA/cm3). The trabecular number was not significantly different between quadrants. Trabecular thickness was significantly lower in the anterolateral (0.1417 mg of HA/cm3) and anteromedial (0.1416 mg of HA/cm3) quadrants compared to the posteromedial (0.1809 mg of HA/cm3) quadrant. The posterior half of the radial head was found to have a higher density of columns and arches compared to the anterior half. The microstructure of trabecular bone in the distal radius forms columns, struts, and arches, which allow for efficient transmission of stress through the bone. The microstructure of the radial head has similar microarchitecture to the distal radius with the present study identifying the presence of columns and arches in the radial head. These structures, along with trabecular density, in the posterior radial head may explain the lower incidence of fractures involving the posterior half of the radial head. Furthermore, our study supports the idea that the high incidence of fractures involving the anterolateral quadrant is due to microarchitecture characteristics and the relative lack of supportive structures compared to other areas. The novel insight gained from this study will aid in the development of advanced interventions for preventative measures and better treatment of radial head fractures like more satisfactory purchase when screws are directed towards the denser posteromedial quadrant.

A retrospective study of Monteggia fractures in 8 dogs and 1 cat.

Monteggia fractures (MFs) are proximal ulnar fractures with concurrent dislocation of the radial head. This retrospective study aims to report the clinical findings and discuss the treatments and outcomes in MFs cases of 9 cases. Previous medical records of the animals were reviewed for history, clinical features, radiographic findings and choice of treatment. Treatment follow-up was evaluated over the telephone by discussion with the owners. Six animals included in the study were presented 2 days after the initial trauma. Five dogs were presented after common road traffic accidents and two after unknown traumas. All dogs had type I MFs, while the cat had a type III MF. Radiographical findings showed that six animals had extra-articular ulnar fractures, while three animals had intra-articular ulnar fractures. All animals were treated with open reduction of the ulna and internal fixation surgical methods. Six ulnar fractures were stabilized with intramedullary pin(s) with cerclage wire. The clinical outcome was assessed by the owners as full function in 3 dogs, acceptable function in 2 dogs and unacceptable function in 2 dogs with intraarticular ulnar fractures. The cat case was rated as full function. One dog died from a pulmonary fat embolism. The findings presented here provide some support that cerclage wire placement could be a satisfactory method for annular ligament reconstruction as a simple and economical treatment option. Also, to the authors' knowledge, this is the third report of MFs with intraarticular ulnar fractures. In this series, comminuted, intraarticular fractures were related to major postoperative complications.

Anterior Congenital Radial Head Dislocation in an Adult with Associated Posterior Interosseous Nerve Palsy.

Introduction: Anterior congenital radial head dislocation (CRHD) is a rare abnormality that is less commonly seen in the adult population. Most of the time, adult-onset symptoms are due to the prolonged dislocation of the radiocapitellar joint that has been present since birth. One of the possible complications of having a prolonged radial head dislocation is the presence of neuropathies such as posterior interosseous nerve (PIN) palsy. There has been, however, no literature published regarding the relationship of CRHD with PIN palsy. Case Report: We here report a 66-year-old male incidentally diagnosed with anterior CRHD with concomitant PIN palsy after acquiring a fracture of the lateral humeral condyle. Open reduction internal fixation of the lateral condyle was done along with decompression of the said nerve. PIN palsy was completely recovered 2 months after surgery. Conclusion: Surgeons must be aware that PIN palsies can occur in the presence of a chronic radial head dislocation, even if asymptomatic. Prompt nerve decompression as well as removal of the mechanical block is pertinent to avoid the perilous effects of an irreversible PIN palsy.

Comprehensive Classification of the Capitellar Injury Concurrent with Radial Head Fracture.

BACKGROUND: Capitellar injury (CI) includes capitellar cartilage injury (CCI) and capitellar fracture (CF). A comprehensive classification of CI concurrent with radial head fracture (RHF) that can guide surgical strategy is lacking in the literature. Therefore, this study aimed to introduce a comprehensive classification of CI concurrent with RHF and investigate its value. METHODS: A total of 35 patients with CI concurrent with RHF confirmed by surgical exploration were retrospectively analyzed, includingmales in 19 cases and females in 16 cases. RHF was classified according to the Mason classification, and CI was classified into six types, including 3 types of CCI and CF, each based on the site and degrees of injuries (comprehensive classification method proposed in this study). The classification results were analyzed. Two radiologists were selected to independently classify the CI, and the inter- and intra-observer agreements were analyzed with kappa statistics. RESULTS: Mason Type I, II, III, and IV RHF accounted for 14.3%, 48.6%, 37.1%, and 0% of cases, respectively. Type I, II, III, IV, V, and VI CIs accounted for 22.9%, 34.3%, 25.7%, 11.4%, 2.9%, and 2.9% of cases, respectively. Therewas no obvious relationship between the CI and RHF types (p > 0.05). All Type I CIs underwent removal, 9 Type II CIs underwent microfracture repair, and 3 Type II CIs underwent removal. All Type III CIs underwent fixation, one Type IV CI underwent removal, and 3 Type IV CIs underwent fixation, one Type V CI underwent fixation, and one Type VI CI underwent arthroplasty. The inter- and intra-observer kappa coefficients were 0.830 ~ 0.905 and 0.805 ~ 0.892, respectively. At 12 months postoperatively, the elbow function evaluated by MEPS was 91, with an excellent and good rate of 97%. CONCLUSION: Different types of CI differ not only in pathology but also in treatment methods. The CI comprehensive classification put forth in this paper for the first time reflects different types of pathology well, with high consistency and repeatability, and can guide the selection of surgical methods, leading to satisfactory postoperative results.

FRACTURE-DISLOCATIONS OF THE ELBOW: CAN THEY INFLUENCE THE PATTERN FRACTURE OF RADIAL HEAD?

Introduction: Radial head fractures are consistently part of a terrible triad of the elbow and can occur in association with Monteggia fracture-dislocations, transolecranon fractures, and their variations. Understanding the degree of comminution of the radial head fracture and the location of fragments determines the course of action to be taken. Objectives: To correlate fracture-dislocations with the pattern of radial head fracture (number of fragments) and involvement in the proximal radioulnar region. Materials and Methods: A retrospective study (level II) of patients undergoing surgery for radial head fractures associated with fracture-dislocations. Patients had radiographs in anteroposterior and lateral views, as well as tomography. The number of radial head fracture fragments and the presence of fractures in the proximal radioulnar region were correlated with the type of fracture-dislocation and demographic variables. Conclusion: Elbow fracture-dislocation types could not predict the number of fragments and the location of radial head fractures. However, most injuries presented three or more fragments in the radial head, and many had involvement of the proximal radioulnar region, suggesting high-energy trauma. Level of Evidence II; Retrospective Study.

Introdução: As fraturas da cabeça do rádio estão sempre presentes em uma tríade terrível do cotovelo e podem ocorrer associadas a uma fratura-luxação de Monteggia, fratura transolecraniana e suas variações. Conhecer o grau de cominuição da fratura da cabeça do rádio e a localização dos fragmentos determinam a conduta a ser tomada. Objetivos: Correlacionar as fraturas-luxações com o padrão da fratura da cabeça do rádio (número de fragmentos) e o acometimento na região radioulnar proximal. Material e Métodos: Estudo retrospectivo (nível II) de pacientes submetidos a cirurgia devido fraturas de cabeça de rádio associadas às fraturas-luxações. Os pacientes possuíam radiografia nas incidências anteroposterior e perfil e tomografia. O número de fragmentos da fratura da cabeça do rádio e a presença de fratura na região radioulnar proximal foram correlacionadas com o tipo de fratura-luxação e as varáveis demográficas. Conclusão: Os tipos de fratura-luxação do cotovelo não foram capazes de predizer o número de fragmentos e a localização da fratura da cabeça do rádio. Entretanto, a maioria das lesões apresentaram três ou mais fragmentos na cabeça do rádio e muitos apresentaram acometimento da região da radioulnar proximal sugerindo traumas de alta energia. Nível de Evidência II; Estudo Retrospectivo.

Isolated lateral radial head dislocation in a child: A case report and literature review.

INTRODUCTION: Radial head dislocations in children can result from congenital anomalies, traumatic events, or as part of more complex injuries like Monteggia fractures. These dislocations are rare and may be overlooked unless considered in differential diagnoses. CASE PRESENTATION: We describe a unique instance of a post-traumatic isolated lateral radial head dislocation in a 5-year-old boy with no previous medical concerns. The child presented with persistent pain and limited mobility in the left elbow following an unwitnessed fall at home. Diagnosis was confirmed via radiographs showing the dislocation without associated fractures. Closed reduction under anesthesia was successfully performed. CLINICAL DISCUSSION: This case underscores the importance of a high index of suspicion and thorough imaging in diagnosing pediatric radial head dislocations. Our discussion includes a review of the literature and the clinical approach for managing such injuries, highlighting the specifics of the closed reduction technique used. CONCLUSION: Isolated lateral radial head dislocations, although rare, can occur and are amenable to closed reduction. This case contributes to the limited reports of such dislocations in pediatric patients, emphasizing the need for awareness and precise management strategies to prevent long-term complications.

Usefulness of multiple bioabsorbable Mg screws/K­wires for comminuted radial head fractures.

PURPOSE: We hypothesized that multiple absorbable screws/K-wires would be effective for native head preservation in comminuted radial head fracture fixation (com-RHFs). METHODS: Seventeen patients who met the inclusion criteria between 2018 and 2020 were included. Radiologic findings indicating proper union and clinical outcomes such as the range of elbow motion, visual analog scale score, and Mayo Elbow Performance Score were assessed prospectively after surgery and at least three years of follow-up. RESULTS: The mean follow-up period was 4.6 years. Eleven, one, three, and two patients presented with isolated com-RHFs, type 2 (accompanied injury of medial collateral ligament), type 4 ("terrible triad") fractures, and type 5 posterior olecranon fracture-dislocations, respectively. Union was achieved after a mean of nine weeks postoperatively. The head and shaft angles did not differ significantly from the contralateral normal values (p = 0.778 and 0.872, coronal and sagittal, respectively). At the final follow-up, the mean flexion-extension/pronation-supination arcs were 126.47 ± 4.92°/135.59 ± 10.13°, and thus were significantly different from those on the contralateral side (p < 0.001, both), however the arcs were functional ranges for ordinary daily life. Also, functional status was satisfactory in all individuals. The arthritis grade and extent of heterotrophic ossification were satisfactory in all cases, and there were no serious complications requiring revision surgery. CONCLUSIONS: Absorbable screw/K-wire fixation for com-RHFs is an option before radial head arthroplasty associated with a low complication rate and no need for revision.

Stress shielding following radial head arthroplasty: the impact of preoperative bone quality.

BACKGROUND: We sought to assess if the medullary diameter to cortical width ratio (MD:CW), canal flair index (CFI), and canal fill (CF) of the proximal radius were associated with the presence of stress shielding (SS) after a MoPyC radial head arthroplasty. MATERIALS AND METHODS: We conducted a retrospective, international, multicenter (4 centers) study. A total of 100 radial head arthroplasties in 64 women and 36 men with a mean age of 58.40 years ± 14.90 (range, 25.00-91.00) were included. Radiographic measurements, including MD:CW, CFI, CF, and postoperative SS were captured at a mean follow-up of 3.9 years ± 2.8 (range, 0.5-11). RESULTS: SS was identified in 60 patients. Mean preoperative MD:CW, CFI, and CF were 0.55 ± 0.09, 1.05 ± 0.18, and 0.79 ± 0.11, respectively. The presence of SS was significantly associated with MD:CW (adjusted odds ratio = 13.66; P = .001), and expansion of the stem (adjusted odds ratio = 3.78; P = .001). The amount of the SS was significantly correlated with expansion of the stem (aß 4.58; P < .001). CONCLUSIONS: Our study found that MD:CW was an independent risk factor of SS after MoPyc radial head arthroplasty. Autoexpansion of the MoPyc stem significantly increased the risk of SS and its extent. Further studies involving multiple implants designs are needed to confirm the preliminary observations presented in the current study.

Which radial head fractures are best treated surgically?

Despite the common occurrence of radial head fractures, there is still a lack of consensus on which radial head fractures should be treated surgically. The radial head is an important secondary stabilizer in almost all directions. An insufficient radial head can lead to increased instability in varus-valgus and posterolateral rotatory directions, especially in a ligament-deficient elbow. The decision to perform surgery is often not dictated by the fracture pattern alone but also by the presence of associated injury. Comminution of the radial head and complete loss of cortical contact of at least one fracture fragment are associated with a high occurrence of associated injuries. Nondisplaced and minimally displaced radial head fractures can be treated non-operatively with early mobilization. Displacement (>2 mm) of fragments in radial head fractures without a mechanical block to pronation/supination is not a clear indication for surgery. Mechanical block to pronation/supination and comminution of the fracture are indications for surgery. The following paper reviews the current literature and provides state-of-the-art guidance on which radial head fractures should be treated surgically.

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.

Added transverse screw in tripod construct increases stiffness in Mason III radial head fractures: a finite element analysis.

BACKGROUND: The tripod screw configuration has been shown to offer similar stiffness characteristics to a laterally placed plate. However, concern has been raised that the construct may be prone to failure in scenarios where the screw intersects at the fracture line. We performed a finite element analysis to assess potentially ideal and unideal screw placements in the tripod construct among Mason III radial head fractures. METHODS: A 3-dimensional proximal radius model was developed using a computed tomography scan of an adult male radius. The fracture site was simulated with a uniform gap in transverse and sagittal planes creating a Mason type III fracture pattern comprising 3 fragments. Three configurations were modeled with varying screw intersection points in relation to the radial neck fracture line. A fourth configuration comprising an added transverse interfragmentary screw was also modeled. Loading scenarios included axial and shear forces to simulate physiological conditions. Von Mises stress and displacement were used as outcomes for analysis. RESULTS: Some variation can be seen among the tripod configurations, with a marginal tendency for reduced implant stress and greater stiffness when screw intersection is further from the neck fracture region. The construct with an added transverse interfragmentary screw demonstrated greater stiffness (2269 N/mm) than an equivalent tripod construct comprising 3 screws (612 N/mm). CONCLUSION: The results from this study demonstrate biomechanical similarity between tripod screw constructs including where screws intersect at the radial neck fracture line. An added fourth screw, positioned transversely across fragments, increased construct stiffness in our model.

The impact of anatomic alignment on radiocapitellar pressure following radial head arthroplasty.

BACKGROUND: The incidence of radial head fractures is increasing, and radial head arthroplasty (RHA) is being more frequently used as treatment for irreparable fractures. Our objective was to compare radiocapitellar pressure between the native joint and 2 radial head prosthesis conditions: (1) a prosthetic head that was aligned to the forearm axis of rotation and (2) the same prosthesis with an axisymmetric nonaligned head. METHODS: Ten cadaveric specimens received a pressfit radial head prosthesis (Align; Skeletal Dynamics) for both prosthetic testing conditions. Anatomic alignment (AL) was defined as the prosthetic head aligned to the forearm axis of rotation. Axisymmetric alignment (AX) was defined as the prosthetic radial head aligned to the axis of the prosthetic stem. Axial load was applied with the elbow in extension and the forearm pronated. Data were collected using a Tekscan 4000 sensor. RESULTS: The mean pressure in the AL and AX groups were significantly higher than the mean pressure in the native joint. Compared with the native joint, the mean pressure was 19% higher in the AL group and 56% higher in the AX group. Peak pressure beyond 5 MPa occurred in 0 specimens in the native joint group, in 1 specimen (10%) in the AL group, and in 5 specimens (50%) in the AX group. DISCUSSION: Our results demonstrated that a pressfit radial head prosthesis aligned with the forearm axis of rotation yields capitellar pressures that were more similar to the native condition than a nonaligned pressfit prosthesis. These findings suggest that anatomic alignment may optimize capitellar wear properties, improving the long-term durability of radial head arthroplasty.

Long-terms outcomes of radial head arthroplasty using a bipolar prosthesis.

BACKGROUND: In acute treatment of radial head fractures, a radial head prosthesis can be considered if open reduction and internal fixation are not technically feasible. METHODS: We reviewed the data of 27 consecutive bipolar Judet radial head prostheses implanted in patients with unreconstructable radial head fractures and no other concomitant fractures (coronoid or olecranon factures). The lesions of the lateral collateral ligament were rated according to the McKee classification. Twenty-three patients with more than ten-year follow-up participated in this retrospective study All patients underwent assessments for pain, range of motion and stability using the Mayo Elbow Performance Score, the QuickDash questionnaire and a Visual Analogue Scale for pain. Radiography assessment was performed to determine the correct setting of the implant, presence of periprosthetic loosening, prosthetic disassembly, heterotopic ossification, capitellum and ulnohumeral degenerative changes. RESULTS: Mean follow-up was 149 months (± 12.2). Mean range of motion in flexion-extension was 111° (± 10.55), mean extension was 18° (± 14.32) and mean flexion was 130° (± 11.4). Mean arc of motion in supination-pronation was 150° (± 12.26). The mean Mayo Elbow Performance Score was 88, the mean QuickDash score was 7.3; 86% of the patients were satisfied. Seven patients (26%) required secondary surgery. The most frequent complication was heterotopic ossification, which had negative consequences on the functional result. CONCLUSIONS: Bipolar radial head prostheses are an option for acute treatment of isolated unreconstructable radial head fractures. During follow-up, three patients required implant revision and removal; the capitellum surface presented severe degenerative changes and the prosthesis was not replaced. Another complication was the risk of implant dislocation, in relation to implant design, incorrect positioning of the radial head stem or else to inadequate reconstruction of the lateral collateral ligament. Further work is needed to establish the long-term follow-up results of Judet implants in complex elbow fractures.

Early range of motion results in good elbow function following conservative treatment of non-displaced radial head fractures.

INTRODUCTION: The aim of this study was to evaluate the range of motion (ROM), elbow function and predictors for good elbow function after conservative treatment of non-displaced radial head fractures. MATERIAL AND METHODS: All patients with non-displaced radial head fractures (displacement < 2 mm), that were diagnosed between January 1st 2017 and December 31st 2021 in a level I trauma center, were included in this retrospective case series and the charts were evaluated for ROM and elbow function. Elbow function was categorized as "good" or "bad" depending on the ROM measured defined by Morrey et al. Overall, 73 patients (33 male, 40 female) with an average age of 38 years (+/- 13 years) could be included. RESULTS: Conservative treatment had good clinical results for ROM and elbow function. After 6 weeks mean flexion was 131° (SD 13°), extension 8° (SD 7°), Pronation 83° (SD 11°) and Supination 83° (SD 13). Patients with a good elbow function after one week showed a good elbow function after completing the treatment. CONCLUSIONS: A clinical assessment after one week should always be performed and the study showed that it is a good predictor for good elbow function. In cases of bad elbow function further controls should be considered.