Introduction. A prospective study was done using Kirschner (K) wires to internally fix capitellum fractures and its results were analysed. Materials/Methods. Since 1989, unstable displaced 17 capitellum fractures were anatomically reduced and internally fixed by inserting K wires in coronal plane from the capitellum into trochlea. The lateral end of wires were bent in form of a staple behind the fracture plane and anchored into the lateral humeral condyle with pre-drilled holes. Additional screws were used in 2 cases to stabilise the lateral pillar comminution. The capitellum was exposed with a limited modified lateral elbow approach between anconeus and extensor carpi ulnaris. The capsule was reflected anteriorly to expose the capitellum and trochlea. The deeper dissection was limited anterior to lateral collateral ligament (LCL) keeping it intact. The capitellum fragment was reposition under the radial head and anatomically reduced by full flexion of elbow and then internally fixed. Total 17 patients (7 males and 10 females) with average ages 34.8 years(14 to 75) had fractures, Type I: (Hans Steinthal #) 12, Type II: (Kocher Lorez #) 1, and Type III: (Broberg and Morrey #) 4. Post-operatively the patients were not given any immobilisation and were mobilised immediately. Results. Patients were assessed clinically and radiologically. Average followup was 31.7 (18–35) months. Capitellum fractures healed in all the patients. Mayo elbow score was excellent in 12, good in 4, and fair in 1 patient. Average elbow ROM was 5 to 132 degrees, pronation 84.5 (79–90) degrees and supination 88 (85–91) degrees. Complications seen were wire pain in 4 patients, loosening of wires in 2 which required early removal. We did not see any infection, non-union or avascular necrosis in the time scale we studied. Conclusions. We found a simple manoeuvre of hyper-flexion of elbow reduced the capitellum anatomically, and K wires stapling technique to be very easy and stable. A limited exposure of capitellum helped to restore immediate stable elbow with good function

The functional outcomes of twenty-eight patients with capitellum and trochlea fractures treated with open reduction and internal fixation were evaluated at a mean follow-up of fifty-five ± thirty-three months. Patients were independently evaluated by a series of questionnaires, radiographs, physical examination and strength testing. Patients with simple fractures did better than those with complicated fractures. The average DASH score was 19/100 and the average ROM was 20 – 130°. Two fractures did not unite and required conversion to total elbow arthroplasty. A classification system is proposed based on fracture patterns, surgical technique and clinical outcomes. Capitellum and trochlea fractures are uncommon fractures of the distal humerus. There is limited information about the functional outcome of patients managed with open reduction and internal fixation. The functional outcome of twenty-eight patients (average age: forty-three ± thirteen years [range, twenty – seventy-one]) who were treated with open reduction and internal fixation for capitellum and trochlea fractures was evaluated at a mean follow-up of fifty-five ± thirty-three months (range, fourteen – one hundred and twenty-one). Patient outcomes were assessed by physical examination, radiographs, range of motion measurements, strength testing and self reported questionnaires (DASH, SF-36 ASES and PREE elbow scales). There were eleven fractures involving the capitellum, four involving the capitellum and trochlea as one piece and thirteen in which the capitellum and trochlea were separate fragments. These fractures were further defined by the presence or absence of posterior comminution. Fourteen had isolated fractures and fourteen were associated with other elbow, forearm or wrist injuries. Patients with complicated fractures required more extensive surgery, had more complications resulting in secondary procedures and had poorer outcomes compared to those with simple fractures. The average DASH score (19/100), quality of life scores (SF-36: Physical=46, Mental=49) and the average ROM (20 – 130°) suggest favorable patient outcomes overall. Patients with simple fractures had better results than those with more complicated fractures. A fracture classification system based on fracture patterns, surgical technique and clinical outcomes is proposed

Purpose: The identification of anatomical landmarks is an important aspect of joint surgery, to ensure proper placement and alignment for implants and other reconstructive procedures. At the elbow, the center of the capitellum (derived via a digitization of the surface and subsequent sphere fitting) has been well established as a key landmark to identify the axis of rotation of the joint. For some cases, and in particular minimally invasive surgery, only small regions of the capitellum may be exposed which may lead to errors in determining the centre. The purpose of this study was to identify the optimal location of digitizations of the capitellum. Method: Twenty-five fresh frozen cadaveric distal humeri (19 left, 6 right) were studied. Using an x-ray computed tomography scanner, volumetric images of each specimen were acquired and used to reconstruct a 3-dimensional digital model of the specimen using the Visualization Toolkit (VTK). A sphere-fit algorithm was used to determine the centre of the spherical capitellum based on manually chosen (digitized) points across the 3D capitellar surface. The true geometric centre was located by digitizing points across the entire capitellar surface. Three sub-regions of the capitellum, commensurate with typical surgical approaches with minimal dissection, were then digitized. These were superior anterior lateral (SAL), inferior anterior lateral (IAL) and a combination of these two regions. These regions were compared to the true center using a 1-way Repeated Measures ANOVA with significance set to p = 0.05. Results: Digitizations of only SAL and IAL sub-regions resulted in the largest differences relative to the true centre: SAL = 3.9±3.4 mm, IAL = 4.2±3.4 mm, (p < 0.0005). There was no difference between SAL and IAL (p = 1.0). Digitization of the combined SAL + IAL regions, while significantly different from the entire capitellum, resulted in the smallest mean difference of 0.87±0.84 mm. Conclusion: These data show that the region of digitization affects the accuracy of predicting the capitellum centre. In a previous study by our group, we showed that an accurate determination of the centre of a sphere can be achieved with a small surface area of digitization. In the current study, the large errors that occurred when a small surface was digitized (i.e. SAL and IAL alone), are in all likelihood, due the non-spherical nature of the capitellum. In summary, while the most precise method in locating the true centre is to digitize the entire capitellar surface where possible, an alternative approach is to digitize both the superior and inferior anterior lateral regions

Purpose: The literature contains little information on an objective method of measuring radiocapitellar joint translations, as would be seen with joint instability. The purpose of this study was to develop and validate a measurement method that was simple and that could be easily reproducible in a clinical setting or intra-operatively to assess radiocapitellar joint translations. Method: We performed a radiological study on a synthetic elbow specimen in order to quantify radial head translations as related to the capitellum: the Radio-capitellum ratio (RCR). Thirty (30) lateral elbow x-rays were taken in different magnitude of subluxation of the radial head. The subluxation was created randomly by manipulation. X-rays where taken by fluoroscopy to obtain a perfect lateral view of the distal humerus. First, the evaluators determined the long axis of the radius and the center of the capitellum. The displacement of the radial head (in mm) was obtained by measuring the distance of the line perpendicular to the long axis of the radius passing through the center of the capitellum. Then, in order to adjust for variation of magnification, a ratio of the displacement of the radial head about the diameter of the capitellum was done. The RC ratio would be of zero because the long axis of the radius always crosses the center of the capitellum in a perfectly aligned joint. A five mm translation of the radial head and a capitellum diameter of twenty (20) mm would give a RCR of 25% and would be positive if anterior and negative if posterior. The measurements were done two times at one week intervals by three independent evaluators to test inter-observer agreement and intra-observer consistency. The radiological incidences were randomly ordered to minimize observer recall bias. Intra/inter-observer reliability was calculated using Intra-Class Correlation (ICC) and paired T-tests. Results: The mean translation in the trial group was of 6,06% (SD 70.7%) from – 167% to 125%. A result over 100% means that it is a complete dislocation ie – the axis of the radius is outside of the capitellum. Negative values signify posterior translation and positive values an anterior translation. Intra-observer reliability was excellent for the Radio-capitellum ratio (ICC 0.988 and 0.995) and inter-observer reliability was excellent (ICC 0.984 in average). Paired T-test results confirm a high intra-observer repeatability (p=0.97 and p=0.99) as well as a large inter-observer reproducibility (p=0.98 in average). Conclusion: The proposed measurement of radial head translation about the capitellum (in percent): radio-capitellum ratio (RCR) has excellent inter – and intra-observer reliability when using our measurement method

Purpose: Osteochondritis dissecans (OCD) of the capitellum most commonly affects adolescent pitchers and gymnasts, and presents with pain and mechanical symptoms. Fragment excision is the most commonly employed surgical treatment; however, patients with larger lesions have been reported to have poorer outcomes. It’s not clear whether this is due to increased contact pressures on the surrounding articular surface, or if fragment excision causes instability of the elbow. The purpose of this study was to determine if fragment excision of simulated OCD lesions of the capitellum alters kinematics and stability of the elbow. Method: Nine fresh-frozen cadaveric arms were mounted in an upper extremity joint motion simulator, with cables attaching the tendons of the major muscle tendons to motors and pneumatic actuators. Electromagnetic receivers attached to the radius and ulna enabled quantification of the kinematics of both bones with respect to the humerus. Three-dimensional CT scans were used to plan lesions of 12.5% (mean 0.8cm2), 25%, 37.5%, 50%, and 100% (mean 6.2cm2) of the capitellar surface, which were marked on the capitellum using navigation. Lesions were created by burring through cartilage and subchondral bone. The arms were subjected to active and passive flexion in both the vertical and valgus-loaded positions, and passive forearm rotation in the vertical position. Results: No significant differences in varus-valgus or rotational ulnohumeral kinematics were found between any of the simulated OCD lesions and the elbows with an intact articulation with active and passive flexion, regardless of forearm rotation and the orientation of the arm (p> 0.7). Radiocapitellar kinematics were not significantly affected during passive forearm rotation with the arm in the vertical position (p=0.07–0.6). Conclusion: In this in-vitro biomechanical study even large simulated OCD lesions of the capitellum did not alter the kinematics or laxity of the elbow at either the radiocapitellar or ulnohumeral joints. These data suggest that excision of capitellar fragments not amenable to fixation can be considered without altering elbow kinematics or decreasing stability. Further study is required to examine other factors, such as altered contact stresses on the remaining articulation, that are thought to contribute to poorer outcomes in patients with larger lesions

Aims. To propose a new method for evaluating paediatric radial neck fractures and improve the accuracy of fracture angulation measurement, particularly in younger children, and thereby facilitate planning treatment in this population. Methods. Clinical data of 117 children with radial neck fractures in our hospital from August 2014 to March 2023 were collected. A total of 50 children (26 males, 24 females, mean age 7.6 years (2 to 13)) met the inclusion criteria and were analyzed. Cases were excluded for the following reasons: Judet grade I and Judet grade IVb (> 85° angulation) classification; poor radiograph image quality; incomplete clinical information; sagittal plane angulation; severe displacement of the ulna fracture; and Monteggia fractures. For each patient, standard elbow anteroposterior (AP) view radiographs and corresponding CT images were acquired. On radiographs, Angle P (complementary to the angle between the long axis of the radial head and the line perpendicular to the physis), Angle S (complementary to the angle between the long axis of the radial head and the midline through the proximal radial shaft), and Angle U (between the long axis of the radial head and the straight line from the distal tip of the capitellum to the coronoid process) were identified as candidates approximating the true coronal plane angulation of radial neck fractures. On the coronal plane of the CT scan, the angulation of radial neck fractures (CTa) was measured and served as the reference standard for measurement. Inter- and intraobserver reliabilities were assessed by Kappa statistics and intraclass correlation coefficient (ICC). Results. Angle U showed the strongest correlation with CTa (p < 0.001). In the analysis of inter- and intraobserver reliability, Kappa values were significantly higher for Angles S and U compared with Angle P. ICC values were excellent among the three groups. Conclusion. Angle U on AP view was the best substitute for CTa when evaluating radial neck fractures in children. Further studies are required to validate this method. Cite this article: Bone Joint J 2024;106-B(9):964–969

Aims: This study aimed to assess the outcome of arthroscopic debridement and removal of loose bodies from the elbows of patients with OCD of the capitellum who had previously failed non-operative treatment. Methods: Patients who had been treated arthroscopically for symptomatic OCD of the capitellum after failing non-operative management for 6 months were invited for review. They were assessed clinically, by an independent examiner using a modern elbow outcome score, and radiologically. In addition details of sporting involvement and satisfaction of outcome were ascertained. Results: 29 patients/elbows (91% follow up rate) were assessed at a mean follow up period of 77 months. There were 20 males and 9 females with an average age at operation of 22 years. There were no operative complications. 26 patients had none or mild pain and were able to complete activities of daily living with minimal impairment. 27 patients had been regularly involved in sports (Olympic and professional to recreational levels) only 4 of whom had to give up the sport because of ongoing problems. 5 of 6 elite gymnasts and 10 of 11 rugby players were able to fully resume their sport. 11 patients (38%) had recurrence of locking episodes. There was an average 5û loss of ßexion and a 10û loss of extension while the grip strength remained normal. Radiographs demonstrated that most of the capitella had not remodelled. 28 (97%) patients had a good or excellent outcome. Conclusions: This study has demonstrated that arthroscopic treatment of recalcitrant OCD of the capitellum is a safe procedure resulting in satisþed patients most of whom can return their previous level of sports but there is a risk of recurrent locking symptom

The purpose of this study is to describe a surgical procedure for unstable osteochondritis dissecans (OCD) of the capitellum and its results. Between 1992 and 1997, 11 elbows of 11 patients with OCD of the capitellum were treated in our institution. The average age at surgery was 14.7 years and the ages ranged from 12 to 16 years. All patients were male baseball players affected in the throwing side. The follow-up period was from 31 to 95 months (average: 57 months). All patients underwent internal fixation using the pull out wiring method and bone graft (this procedure was established by Kondo in 1989). All lesions of OCD were not only softening or cracked but also unstable with early separation or partially detached fragment. After surgery, a long arm cast was applied for 3 weeks. After confirming bony union of OCD by X-ray, the wires were removed ranged from 15 to 21 weeks (average 17 weeks) postoperatively. Throwing activity was allowed 6 months after surgery. At the follow-up, all patients were relieved pain and all except one returned to previous throwing levels. Radiographs showed good healing of OCD and minimum degenerative changes were found in only a few joints. We concluded that this surgical procedure was an effective treatment for adolescent baseball players with unstable OCD of the capitellum

Displaced supracondylar fractures of the paediatric elbow are a serious, but well described injury. Although complications are common, avascular necrosis (AVN) of the capitellum has not been described or reported before. We describe a case with this complication. A review of the relevant literature is also presented. A three-year-old boy presented to our emergency department with a painful swollen left elbow after a fall. X-ray done in Accident and Emergency, reveal, a displaced, extension type, supracondylar fracture (Gartland Grade III. 1. ). An open reduction (medial approach) was done and the fracture reduced and stabilised with two crossed K wires. The fracture healed in an excellent position. However, at the three-month follow up, the elbow remained stiff with flexion from only 20 to 90 degrees and with very little supination. Eight months after the injury an arthrogram was undertaken which confirmed diagnosis of avascular necrosis of capitellum. No specific treatment for AVN given. Check radiographs showed healing of capitellum with no functional limitations

Objectives. Surgical treatment is standard for advanced osteochondritis dissecans (OCD) of the humeral capitellum. When cartilage is seen to be separated or completely detached, this fragment fixation is not usually applied. There have been reports of cases in which advanced OCD of the humeral capitellum progressed to osteoarthritis (Fig), particularly in cases which involved the lateral wall. In these cases, every attempt should be made to reconstruct the lateral wall to avoid osteoarthritis. In this study, we followed up cases with rib osteochondral autograft transplantation technique. Methods. Subjects were 20 cases who were followed up until after they started pitching. The mean age was 13.8 years old and the mean observation period was 2 years and 6 months (from 7 months to 6 year 3 months). Kocher's approach was used to give a good access to the aspect of the radiohumeral joint. The majority of cases suffered from extensive OCD of the elbow. Detached fragment was removed (Fig. 2a) and graft from 5. th. or 6. th. rib with screw fixation was performed on 12 patients and 8 received fixation with no material (Fig. 2b). Follow-up assessment included the range of motion, start time of playing catch and throwing a ball with full power, sports activity, evaluation of radiography, a subjective (including Pain, Swelling, Locking/Catching and Sport activity) and objective (Flexion contracture, Pronation/Supination and sagittal arc of motion) modified elbow rating system by Timmeman et al. We also investigated the details of the arthroscopy observations and the 2nd arthroscopy findings for 4 cases. Results. Preoperative elbow extension increased from −13.5 to −10 degrees and elbow flexion increased from 117 to 123 degrees, but no significant differences were found. All but one patient resumed baseball sporting activity. Catching was started at an average of 3.5 (2 to 5.5 months) months postoperatively and pitching the ball with full power was achieved at 6.7 months. One case was found to have degenerative changes on plain X-ray, and two cases were found to have deviated screws. The mean elbow rating system subjective score improved significantly from 63.9.5 to 89.5 points, as did the overall rating, increasing from 131.6 to 164.8 points. The 2. nd. arthroscopy observations for 4 patients showed that 2 experienced pain due to the loose body, 1 had a limitation in range of motion due to spur formation, and 1 had a screw deviation. Graft survival was observed in two out of four cases. Partial detachment was observed in two cases. Conclusion. Recovery of articular facets with hyaline cartilage were possible using this surgical technique, and in addition, the costal-costochondral grafts, comprising cortical and cancellous bone, were simultaneously transplanted en bloc. This indicates that it is adequate treatment for extensive OCD. All the patients started pitching 3 months postoperatively and returned to full baseball activities after 6 months. Even in cases with extensive OCD, with large osseous and cartilaginous deficits, the surgical technique was useful and showed favorable results

Introduction Osteochondritis Dissecans of the elbow is a rare condition classically affecting teenage males playing throwing sports. The aim of this study was to evaluate the longer term outcome following arthroscopic debridement in patients with osteochondritis of the elbow that had failed conservative management.

Methods All clinically, radiologically and arthroscopically proven patients (since 1989) with Osteochondritis Dissecans (OCD) that had failed six months of non-operative management were recalled for clinical, performance indices and radiological review. A 91% follow-up rate was achieved (62% full clinical and radiological follow-up). The group consisted of 29 patients (20 male, nine female) with an average age of 22 years. Patients were mobilised post-operatively as symptoms allowed.

Results At an average of 77 months after the operation, the majority of patients had mild or no pain with activities of daily living but with some discomfort during heavy lifting/sports. Only four out of 27 had to give up their preferred sport because of persistent elbow problems. Thirty-eight percent had recurrence of locking or catching, though these symptoms were described as much better than prior to the operation and were not felt severe enough to consider any further intervention.

Conclusions We conclude that arthroscopic debridement and removal of loose bodies is a safe and reliable procedure for patients with persistent symptoms from OCD of the elbow.

Hemiarthroplasty is a common procedure that is an attractive alternative to total arthroplasty because it conserves natural tissue, allows for quicker recovery, and has a lower cost. One significant issue with hemiarthroplasties is that they lead to accelerated wear of the opposing native cartilage, likely due to the high stiffness of the implant. The purpose of this study was to investigate the range of currently available biomaterials for hemiarthroplasty applications. We employed a finite-element (FE) model of a radial head implant against the native capitellum as our joint model. The FE model was developed in ABAQUS v6.14 (Dassault Systèmes Simulia Corp., Providence, RI, USA). A solid axisymmetric concave implant with seven different materials and the native radial head were evaluated, six modelled as elastic materials with different Young's moduli (E) and Poisson's Ratios (ν), and one modelled as a Mooney-Rivlin hyperelastic material. The materials investigated were CoCr (E=230 GPa, ν = 0.3), PEEK (E=3.7 GPa, ν = 0.36), HDPE (E=2.7 GPa, ν = 0.42), UHMWPE (E=0.69 GPa, ν = 0.49), Bionate 75D (E=0.288 GPa, ν = 0.39), Bionate 55D (E=0.039 GPa, ν = 0.45), and Bionate 80A (modelled as a Mooney-Rivlin hyperelastic material). A load of 100 N was applied to the radius through the center of rotation representing a typical load through the radius. The variable of interest was articular contact stress on the capitellum. The CoCr implant had a maximum contact stress over 114% higher than the native radial head. By changing the material to lower the stiffness of the implant, the maximum contact stress was 24%, 70%, 105%, 111%, 113%, and 113% higher than the native radial head for Bionate 80A, Bionate 55D, Bionate 75D, UHMWPE, HDPE, and PEEK respectively. This work shows that lowering implant stiffness can reduce the contact stress on cartilage in hemiarthroplasty implants. By changing the material below a Young's modulus of ∼100 MPa elevated stresses on the capitellum can be markedly reduced and hence potentially reduce or prevent degenerative changes of the native articulating cartilage. Low stiffness implant materials are not a novel concept, but to date there have been few that investigate materials (such as Bionate) as a potential load bearing material for implant applications. Further work is required to assess the efficacy of these materials for articular bearing applications

Purpose: Coronal shear fractures of the humerus include the Kocher-Lorenz fracture, an osteochondral fracture of the capitellar articular surface, the Hahn-Steinthal fracture, a substantial shear fragment, extension into the trochlea, and complete involvement of the capitellum and trochlea. If the fracture proves irreparable, it is not known what the impact of fragment excision would have on the biomechanics of the elbow. The purpose of this study was to examine the effect of the sequential loss of the capitellum and trochlea on the kinematics and stability of the elbow. Method: Eight fresh-frozen cadaveric arms were mounted in an upper extremity joint testing system, with cables attaching the tendons of the major muscles to motors and pneumatic actuators. Electromagnetic receivers attached to the radius and ulna enabled quantification of the kinematics of both bones with respect to the humerus. The distal humeral articular surface was sequentially excised to replicate clinically relevant coronal shear fractures while leaving the collateral ligaments intact. Active flexion in both the vertical and valgus-loaded positions, and passive rotation in the vertical position was conducted for each excision. Results: Excision of the capitellum had no effect on ulnohumeral stability or kinematics in both the vertical or valgus positions (p=1.0). Excision of the entire capitellum and trochlea led to significant valgus instability with the arm in the valgus position (p=0.01), while excision of the lateral trochlea led to increased valgus instability with pronated flexion in the valgus position (p=0.049). Progressive loss of the articular surface led to posterior, inferior, and medial displacement of the radial head with respect to the capitellum and increased external rotation of the ulna with respect to the humerus in the vertical position (p< 0.05). Conclusion: Excision of the capitellum did not result in valgus or rotational instability, while excision of the trochlea resulted in multiplanar instability. The radial head displaced medially because it is constrained to the ulna by the annular ligament, and the ulna pivoted into valgus and external rotation on the residual trochlea and medial collateral ligament. In patients with coronal shear fractures, the trochlea must be reconstructed to prevent instability and the potential for secondary degenerative change

Three 3mm transverse slices were sectioned from the distal cancellous region of seven fresh-frozen cadaveric humerii. Each slice was marked with a 3x3mm grid, and subjected to compressive testing using a flat cylindrical indenter (1.6mm diameter). Indentation modulus and strength were calculated for each site, and pooled into nine anatomically-defined regions. The most distal slice had higher moduli values (p< 0.05), and the posterior capitellar region had lower moduli values (p< 0.05). There were no slice or regional differences in strength. This suggests that surgical procedures requiring cancellous fixation utilize the most distal aspect of the humerus while avoiding the posterior capitellum. To quantify the indentation strength and modulus of distal humeral cancellous bone, and identify any regional variations. Cancellous bone modulus in the distal humerus decreases from distal to proximal. The posterior capitellum has a lower modulus than the other regions of the distal humerus. The influence of slice depth emphasizes the importance of minimizing the amount of bone removed during prosthetic replacement. Regional variations in modulus suggest that the posterior capitellum should be avoided during fixation of implants or placement of screws. Three 3mm transverse cancellous bone slices obtained from the distal end of each of seven fresh-frozen cadaveric specimens were subjected to compressive testing using a materials testing machine with a 1.6mm flat cylindrical indenter. Testing was performed in a 3x3mm grid. The indentation modulus and local strength were calculated for each test site, and then averaged into nine regions defined by the capitellum, medial and lateral trochlea, and anterior, central and posterior sections for each slice. Mean modulus was found to be 309.8±242.0 MPa (range: 2.9–1041.7 MPa). Yield strength averaged 4.4±2.5 MPa (range: 0.6–16.3 MPa). The highest modulus was found in the distal-most slice (p< 0.05). The lowest modulus region was the posterior capitellum (p< 0.05). There were no differences in strength between slices or across the nine regions. A comparison with proximal tibial cancellous bone properties suggests the distal humerus may carry loads approaching 30% of those at the knee, assuming that bone adapts to stress magnitudes. Funding: Natural Sciences and Engineering Research Council; University of Western Ontario

Purpose. Capitellum hemiarthroplasty is an emerging concept. The current metallic capitellar implants have spherical surface shapes, but the native capitellum is not spherical. This study evaluated the effect of capitellar implant shape on the contact mechanics of the radiocapitellar joint when articulating with the native radial head. Method. Eight paired radii and humeri were potted in a custom jig. Articular casts were made with medium-viscosity resin while 85 N of axial load was applied to the reduced radiocapitellar joint at 0, 45, and 90 of elbow flexion, and at neutral, 50 pronation and 50 supination at each flexion angle. The native radiocapitellar articulation was compared to capitellar hemiarthroplasties of two surface designs (anatomical and spherical). Contact area and shape (circularity) were determined. Circularity was defined as the ratio of the minor axis and major axis of the shape. Results. At 0 of flexion, the anatomical hemiarthroplasty had a contact area of 52–70% that of the native articulation (p=0.03), while the spherical hemiarthroplasty had a contact area 40–42% that of the native articulation (p=0.003). At 45 of flexion, both hemiarthroplasties displayed contact area <53% that of the native joint (p<0.007). At 90 of flexion, the hemiarthroplasties had contact areas ranging from 40–70% that of the native articulation (p=0.1). The two capitellar implants had similar contact areas at all flexion angles tested (p>0.05). The contact shape of the native radiocapitellar articulation was ellipsoid, with a range of circularity values from 0.530.19 to 0.720.16, depending on the flexion and rotation angle. At 0 and 90 flexion, there was no difference in contact shape between the native articulation, the anatomical, or spherical implant (p>0.05). At 45 flexion, the anatomical implant contact was less circular than either the native articulation (p=0.006) or the spherical hemiarthroplasty (p=0.002). Conclusion. Metallic capitellar hemiarthroplasty causes a significant reduction in contact area at 0 and 45 elbow flexion, which may have important long-term implications for wear of the radial head cartilage. This reduction is similar to previous reports, which have evaluated the effect of metallic radial head hemiarthroplasty articulating with the native capitellum. More compliant alternative materials are needed to improve the contact characteristics of metallic capitellar hemiarthroplasties. Although the anatomical hemiarthroplasty was created from a detailed morphological study of the capitellum, the anatomical implant failed to completely reproduce the contact native shape. The theoretical advantages of a more anatomical capitellar implant shape may not be realized clinically, suggesting a spherical implant, which is easier to manufacture and implant, may be adequate for patient application. Further studies are required to delineate the effect of this altered contact morphology on implant function and radial head wear in-vivo

Background. Fractures of the radial head result from an axial force that causes impaction against the capitellum. Associated lesions of the capitellum in this pattern of injury have been previously reported in the orthopaedic literature as an uncommon occurrence. Methods. All patients presenting to the clinics of the senior surgeon between 1998-2008 with radial head fractures requiring surgery were included. Data collected included demographics (age, gender, side of injury), mechanism, timing of injury and injury type (Mason classification). Intraoperative findings including evidence of union, capitellar injury, associated joint dislocation, collateral ligament injury, and any other fractures around the elbow were documented. Results. We reviewed 109 consecutive patients presenting with radial head fractures. 67% of the patients were found to have the PLUCCAR lesion, a capitellar slither of cartilage impacted in the radial fracture. Of these, 76.9% of patients with a Mason I injury had a PLUCCAR lesion, 76.7% of patients with Mason II injury had a PLUCCAR lesion, and only 33.3% of patients with Mason III lesion had a PLUCCAR lesion. 13 patients had a pre-existing non-union, 84% of whom had a PLUCCAR lesion. 19 patients were found to have a malunion, 84% of whom were found to have the PLUCCAR lesion. Conclusion. Injury to the capitellum is commonly associated with radial head fracture. We term impaction of a capitellar fragment in the radius a PLUCCAR lesion. There is an increased incidence of this injury in less comminuted radial head fractures, and in patients presenting with non union or malunion of a radial head fracture

Summary. The significance of matching radius of curvature of the radial head implant and the capitellum in implant selection is evaluated. A mismatch of radius of curvature could lead to point loading, reducing contact area, creating large contact stresses, resulting in arthritis, pain, and other complications. Introduction. Radial head (RH) implant size is chosen by reconstruction outside of the radiocapitellar joint capsule measuring the RH diameter and length, which is replicated for implant selection. RH radius of curvature (RC) is rarely part of the decision although important in determining contact area. Methods. Eleven fresh-frozen cadaver humeri were denuded, with articular cartilage intact. These were held horizontally in an MTS machine; capitellum faced up, and covered with a Tekscan transducer. RH implants were attached by vice to the MTS driving piston. Four different RH implant models were compared: Ascension, Integra Katalyst, Stryker Small and Medium, all CoCr. All implants were 21mm in outer diameter, except the Stryker small implant (18mm). Cyclic axial loading was applied through the RH implant to the capitellum. Contact area and stress concentrations were captured by the transducer. Loading was applied with stroke control until steady state loading occurred between specified values of 115N-65N, within 1N of peak and 5N of base values. Using the Stryker 21mm implant loading at 155N-65N and 195N-105N simulated over-sizings of +2mm and +4mm. Results. Percent difference between RH and Capitellar RC's were plotted against corresponding Contact Areas of 21mm sized RH implants, and a linear regression done. Negative values corresponded with larger RH than capitellar RC values. The resulting slope was 92.19, showing a significant increase in contact area with decreased RH to capitellar ratios, with an R. 2. value of 0.8122, showing a linear trend. Total stresses were calculated for all maximum contact areas, using the peak values. Discussion. Clinical RH implant sizing comes from native head diameter, not curvature. Improper RC could lead to point loading, reducing contact area, creating large contact stresses, resulting in arthritis, pain, and other complications. This can be seen through the linear relation between contact area and RC. With an RH implant RC of greater value than capitellar RC, the contact area decreases significantly, resulting in increased stress. The significance of RC matching in implant selection. Increases in stress are greater for differences in RC values, than for improper sizing of diameter (D=85.7%) or length (+2mm, +4mm). With the decrease in contact area with increased implant RC, and the changes in stress compared to improper sizings (length and diameter), it can be seen that implant RC is an important feature in RH implant selection

Purpose. The measurement of radial head translation about the capitellum (in percent): the radio-capitellum ratio (RCR) has proven to have excellent inter- and intra-observer reliabilities when measuring the RCR on a lateral radiological view of elbows at 90° of flexion and in the neutral position of the forearm. However, in the clinical setting, radiographs may be taken with the elbow in different positions. However, the purpose was to validate the RCR measurement method on elbows in different positions in flexion-extension and in different positions of the forearm in pronation-supination. Method. Fifty-one healthy volunteers were recruited to evaluate the RCR in different elbow positions. Lateral elbow radiographs were taken with the elbow in different magnitude of ROM: maximal extension, maximal flexion, elbow at 90° and forearm in neutral, elbow at 90° and forearm in supination and elbow at 90° and forearm in pronation. The measurements of the RCR were done using the software SliceOmatic. ANOVA and paired T-test were used to assess the difference of the RCR depending on the position of the elbow and of the forearm. Pearson coefficients were calculated to obtain the correlation between the RCR in each different position. Results. The mean RCR for each position were the following: elbow in maximal extension: −2%±7%, elbow in maximal flexion: −5%±9%, elbow at 90° and forearm in neutral: −2%±5%, elbow at 90° and forearm in supination: 1%±6% and elbow at 90° and forearm in pronation: 1%±5%. According to the Anova results, a significant difference exists between the RCR in different elbow positions (p=0.01) and in the different forearm positions (p<0.001). Paired T-test confirmed a significant difference between maximal elbow flexion and elbow flexion at 90° (p=0.003), as well as for maximal elbow extension and maximal elbow flexion (p=0.034). According to the Pearson coefficient, significant correlations exist between: elbow flexion at 90° and in maximal flexion (r=0.19, p=0.050); the forearm in neutral and in supination (r=0.34, p<0.001); the forearm in neutral and in pronation (r=0.42, p<0.001). Conclusion. The RCR method is dependent on elbow (flexion-extension) and forearm (pronation-supination) positions. At both maximal elbow positions in flexion and extension, the measurements of the RCR have a higher standard deviation. In order to decrease its variability, we recommend as a convention measuring the RCR on lateral radiographs with the elbow at 90° and the forearm in neutral position. However, 95% of the values of RCR (except in maximal flexion which is unusual in trauma) are included in the normal range of RCR from −5% to 13%. Thus a value outside this range in any elbow positions (except maximal flexion) or any forearm positions must raise doubt on elbow alignment. Then, with a capitellum of 25 mm of diameter, the translation of the radial head must be less than 1 mm posterior and less than 3 mm anterior from the center of the capitellum

Total elbow arthroplasty (TEA) usage is increasing owing to expanded surgical indications, better implant designs, and improved long-term survival. Correct humeral implant positioning has been shown to diminish stem loading in vitro, and radiographic loosening in in the long-term. Replication of the native elbow centre of rotation is thought to restore normal muscle moment arms and has been suggested to improve elbow strength and function. While much of the focus has been on humeral component positioning, little is known about the effect of positioning of the ulnar stem on post-operative range of motion and clinical outcomes. The purpose of this study is to determine the effect of the sagittal alignment and positioning of the humeral and ulnar components on the functional outcomes after TEA. Between 2003 and 2016, 173 semi-constrained TEAs (Wright-Tornier Latitude/Latitude EV, Memphis, TN, USA) were performed at our institution, and our preliminary analysis includes 46 elbows in 41 patients (39 female, 7 male). Patients were excluded if they had severe elbow deformity precluding reliable measurement, experienced a major complication related to an ipsilateral upper limb procedure, or underwent revision TEA. For each elbow, saggital alignment was compared pre- and post-operatively. A best fit circle of the trochlea and capitellum was drawn, with its centre representing the rotation axis. Ninety degree tangent lines from the intramedullary axes of the ulna and humerus, and from the olecranon tip to the centre of rotation were drawn and measured relative to the rotation axis, representing the ulna posterior offset, humerus offset, and ulna proximal offset, respectively. In addition, we measured the ulna stem angle (angle subtended by the implant and the intramedullary axis of the ulna), as well as radial neck offset (the length of a 90o tangent line from the intramedullary axis of the radial neck and the centre of rotation) in patients with retained or replaced radial heads. Our primary outcome measure was the quickDASH score recorded at the latest follow-up for each patient. Our secondary outcome measures were postoperative flexion, extension, pronation and supination measured at the same timepoints. Each variable was tested for linear correlation with the primary and secondary outcome measures using the Pearson two-tailed test. At an average follow-up of 6.8 years (range 2–14 years), there was a strong positive correlation between anterior radial neck offset and the quickDASH (r=0.60, p=0.001). There was also a weak negative correlation between the posterior offset of the ulnar component and the qDASH (r=0.39, p=0.031), and a moderate positive correlation between the change in humeral offset and elbow supination (r=0.41, p=0.044). The ulna proximal offset and ulna stem angle were not correlated with either the primary, or secondary outcome measures. When performing primary TEA with radial head retention, or replacement, care should be taken to ensure that the ulnar component is correctly positioned such that intramedullary axis of the radial neck lines up with the centre of elbow rotation, as this strongly correlates with better function and less pain after surgery

Introduction. Isolated trochlea fractures are very rare and have only been described previously as case reports. Aims. To report on a case of isolated trochlea fracture and to present a review of the literature. Results. There have only been four previous reports of isolated trochlea fracture. Our fifth case is included in the analysis of the literature given below. Average age 26 (Range 12–33). 60% female, 80% left sided. Dominance only stated in 40% of cases- 50% dominant side. Mechanism of injury: 60% low velocity fall onto an outstretched hand, 40% high velocity- RTA & fall off horse- exact mechanism of injury unknown. Patients all presented with elbow held in flexion, pain and swelling over the medial aspect and a painfully reduced range of motion. Diagnosis made on plain radiographs in 80%, tomograms required in 20%. AP noted to be essential to differentiate from more common capitellum fracture. 20% of fractures associated with comminution. Management consisted of open reduction through a medial approach and internal fixation in 80% (20% headless screw, 20% k-wire, 40% 4.0mm partially threaded cancellous screws) and olecranon traction in 20%. Elbows were immobilised from 3 to 8 weeks. Time to union ranged from 6 weeks (80%) to 13 weeks (20%). Outcomes were uniformly excellent with 40% being asymptomatic with a FROM, 20% asymptomatic with 10 degrees loss of extension and 40% asymptomatic with 5–20 degrees loss of flexion. There were no reported complications. Conclusion. These are rare injuries and can occur through high and low energy mechanisms. They tend to occur in younger age groups. Diagnosis can be made readily with plain radiographs- the AP is essential in differentiating it from the more common capitellum fracture. The prognosis for this intra-articular fracture is good to excellent