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.

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.

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.

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

INTRODUCTION: 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 (RHA). MATERIAL & METHOD: 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: Stress shielding 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 (aOR=13.66; p=0.001), and expansion of the stem (aOR=3.78; p=0.001). The amount of the SS was significantly correlated with expansion of the stem (aß 4.58; p<0.001). CONCLUSIONS: Our study found that MD:CW was an independent risk factor of SS after Mopyc RHA. Patients with longer and larger diameter (auto-expansion) Mopyc stems were also at significantly increased risk of SS. Further studies involving multiple implants designs are needed to confirm the preliminary observations presented in the current study.

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.

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.

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.

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.

Isolated anterior dislocation of the radial head (case report).

We report the case of an isolated post traumatic radial head dislocation in a 5 year old child. Clinical examination and the X ray results allow the diagnosis which can be unnoticed. The reduction by external maneuvers avoids the surgical treatment which remains the gold standard for chronic dislocation.

Operative treatment of Mason Type III radial head fractures - A comparative analysis using PROMIS.

Objectives: The purpose of this study is to evaluate the outcomes of operatively treated Mason Type III radial head fractures. Additionally, this project seeks to assess efficacy of PROMIS in evaluating post-operative outcomes for this patient population. Methods: A total of 143 patients who underwent operative treated Mason Type III radial head fractures were analyzed retrospectively. PROMIS physical function (PF), PROMIS upper extremity (UE), PROMIS pain interference (PI), demographic variables, and range of motion were collected and analyzed over 12-month follow-up. Results: Radial head arthroplasty (RHA) was performed on 89 patients, open reduction and internal fixation (ORIF) was performed on 47 patients, and radial head excision was performed on 7 patients. Among the RHA patients, PROMIS PF, PI and UE demonstrated a change of -1.33 (p < 0.05), -1.48 (p < 0.05), and 2.23 (p < 0.05) respectively from injury to 12-months. Among the ORIF patients, PROMIS PF, PI and UE demonstrated a change of 3.22 (p < 0.05), -1.56 (p < 0.05), and 2.09 (p < 0.05) respectively from injury to 12-months. At the pre-operative and 12-month visits, the RHA group demonstrated lower PROMIS PF scores 34.75 vs 38.02 (p < 0.05) and 33.42 vs 41.24 (p < 0.05) respectively. Ther was no difference in PROMIS PI, UE, or elbow range of motion between the two groups at 6- or 12-month follow-up (p > 0.05). Conclusion: Comparing the RHA and ORIF groups, there was no difference in PROMIS PI or UE scores nor was there a clinically significant improvement at the 6- or 12-month mark. The ORIF group demonstrated improved PROMIS PF at all follow-up periods and did show a clinically significant improvement. Patient Acceptable Symptom State (PASS) correlated only with PROMIS UE at 6- and 12- months for both groups.

Missed Monteggia Injuries in Children and Adolescents: A Treatment Algorithm.

Monteggia injuries are rare childhood injuries. In 25-50% of cases, however, they continue to be overlooked, leading to a chronic Monteggia injury. Initially, the chronic Monteggia injury is only characterized by a moderate motion deficit, which is often masked by compensatory movements. Later, however, there is a progressive valgus deformity, neuropathy of the ulnar nerve and a progressive deformity of the radial head ("mushroom deformity") with ultimately painful radiocapitellar arthrosis. In the early stages, when the radial head is not yet deformed and there is no osteoarthritis in the humeroradial joint, these injuries can be treated with reconstruction procedures. This can be achieved either by an osteotomy of the proximal ulna with or without gradual lengthening. If there is already a severe deformity of the radial head and painful osteoarthritis, only rescue procedures such as functional radial head resection or radial head resection with or without hemi-interposition arthroplasty can be used to improve mobility and, above all, to eliminate pain. In this review article, we provide an overview of the current treatment options of chronic Monteggia injury in children and adolescents and present a structured treatment algorithm depending on the chronicity and dysplastic changes.

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.

Radial head replacement with the 3D-printed patient-specific titanium prosthesis: Preliminary results of a multi-centric prospective study.

PURPOSE: To report preliminary clinical results and safety of 3D-printed patient-specific titanium radial head (RH) prosthesis in treatment of the irreparable RH fractures. MATERIAL AND METHODS: This multi-centric prospective study included 10 patients (6 men and four women, mean age 41 years (range, 25-64 years)). Three cases were classified as Mason type III and 7 cases as type IV. Patients were assessed preoperatively, intraoperatively, and at 1, 6, 12, 24, 36, and 48 weeks postoperatively. Range of motion (ROM), visual analog scale (VAS) score, Disabilities of the Arm, Shoulder and Hand (DASH) score, Mayo Elbow Performance Score (MEPS), radiology imaging, and laboratory blood and urine testing were evaluated. RESULTS: The prostheses were implanted utilizing cemented stems in 5 patients and cementless stems in 5 patients. Intraoperatively, well congruency of a prosthesis with capitellum and radial notch of ulna was observed in all cases. All patients had improvement of ROM, VAS score, DASH score, and MEPS during the postoperative follow-ups. At the final follow-up, mean elbow extension was 6.5° (range, 0°-30°), flexion 145° (range, 125°-150°), supination 79° (range, 70°-80°), and pronation 73.5° (range, 45°-80°). Mean VAS score was 0.3 (range, 0-3), DASH score was 12.35 (range, 1.7-23.3), and MEPS was 99.5 (range, 95-100). Postoperative radiographs demonstrated heterotopic ossification in 2 cases, periprosthetic radiolucency in 2 cases, and proximal radial neck resorption in 2 cases. No one had the evidence of capitellar erosion, implant failure, malpositioning, overstuffing, or symptomatic stem loosening. There was no significant alteration of laboratory results or adverse events related to the 3D-printed prosthesis implantation. CONCLUSION: The preliminary results demonstrated that implantation of the 3D-printed patient-specific titanium RH prosthesis is safe and may be a potential treatment option for irreparable RH fracture.

A Novel Operation Technique for Forearm Deformities in Patients with Brachial Plexus Birth Injury: Retrospective Analysis of 14 Patients.

Background: We aimed to evaluate the effectiveness of our novel operation technique that included radial shaft shortening plus supination producing osteotomy and transfer of the biceps brachii tendon to the brachialis tendon in patients with chronic radial head dislocation secondary to brachial plexus birth injury (BPBI). Methods: Fourteen patients with chronic radial head dislocation resulting from BPBI were included in this study, with a minimum 1-year postoperative follow-up period. All patients underwent the same surgical procedure. The range of motion of affected elbow was measured with a standard goniometer. The Mayo Elbow Performance Score (MEPS) was used to measure for evaluation of functional result of these patients. The affected elbow radiograph also obtained in the last visit for evaluation of compatibility of the radiocapitellar joint. Results: Fourteen patients (10 males and 4 females) were included in the study. The average age at the time of surgery was 7.2 (5-8) years and average follow-up was 73.2 ± 19 (36-131) months. Although the forearm active-passive pronation decreased, active-passive supination significantly improved postoperatively (p < 0.001). Ten patients had excellent MEPS results (90 and above), two patients with good results (75 and 80), one patient with fair (65) and one patient with poor result (55). Radiocapitellar reduction was achieved in 78.5% (11/14) of the patients. Conclusions: The novel surgical techniques that included radial shaft shortening plus supination producing osteotomy and transfer of the biceps brachii tendon to the brachialis tendon improved the functional outcomes of patients with chronic radial head dislocation secondary to BPBI. Level of Evidence: Level IV (Therapeutic).

Stress Shielding around Press-Fit Radial Head Arthroplasty: Proposal for a New Classification System Based on the Analysis of 97 Patients with a Mid-Term Follow-Up and a Review of the Literature.

Stress shielding (SS) around press-fit radial head arthroplasty (RHA) was recently reported as a cause of a new type of proximal radial neck resorption (PRNR). Very few studies have analyzed this phenomenon. No comprehensive classification is currently available. We thus decided to clinically and radiographically analyze 97 patients who underwent a press-fit RHA and who were followed up for a mean period of 72 months (range: 2-14 years). PRNR in the four quadrants of the radial neck was assessed. We designed a novel SS classification based on (1) the degree of resorption of the length of the radial neck and (2) the number of neck quadrants involved on the axial plane. The mean PRNR (mPRNR) was calculated as the mean resorption in the four quadrants. mPRNR was classified as mild (<3 mm), moderate (3 to 6 mm), and severe (>6 mm). Eighty-four percent of the patients presented PRNR. mPRNR was mild in 33% of the patients, moderate in 54%, and severe in 13%. In total, 6% of the patients with mild mPRNR displayed resorption in one quadrant, 18% displayed resorption in two quadrants, 4% displayed resorption in three quadrants, and 72% displayed resorption in four quadrants. All four quadrants were always involved in moderate or severe mPRNR, with no significant differences being detected between quadrants (p = 0.568). mPRNR has no apparent effect on the clinical results, complications, or RHA survival in the medium term. However, longer-term studies are needed to determine the effects of varying degrees of PRNR on implant failure.

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.