Ulnohumeral Joint Research Articles

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

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

Elbow kinematics with increased lengthening of a radial head arthroplasty evaluated with dynamic radiostereometric analysis.

The aim of this study was to evaluate the kinematics of the elbow following increasing length of the radius with implantation of radial head arthroplasties (RHAs) using dynamic radiostereometry (dRSA). Eight human donor arms were examined by dRSA during motor-controlled flexion and extension of the elbow with the forearm in an unloaded neutral position, and in pronation and supination with and without a 10 N valgus or varus load, respectively. The elbows were examined before and after RHA with stem lengths of anatomical size, + 2 mm, and + 4 mm. The ligaments were maintained intact by using a step-cut lateral humeral epicondylar osteotomy, allowing the RHAs to be repeatedly exchanged. Bone models were obtained from CT scans, and specialized software was used to match these models with the dRSA recordings. The flexion kinematics of the elbow were described using anatomical coordinate systems to define translations and rotations with six degrees of freedom. The greatest kinematic changes in the elbows were seen with the longest, + 4 mm, implant, which imposed a mean joint distraction of 2.8 mm in the radiohumeral joint and of 1.1 mm in the ulnohumeral joint, an increased mean varus angle of up to 2.4° for both the radius and the ulna, a mean shift of the radius of 2.0 mm in the ulnar direction, and a mean shift of the ulna of 1.0 mm posteriorly. The kinematics of the elbow deviated increasingly from those of the native joint with a 2 mm to a 4 mm lengthening of the radius. This confirms the importance of restoring the natural length of the radius when undertaking RHA.

Tendon Lengthening Surgery for Elbow Flexion Contractures in Brachial Plexus Birth Palsy

Flexion contracture of the elbow is a common deformity associated with brachial plexus birth palsy and is often managed with preventive night orthoses. For severe cases, however, surgical interventions may become necessary. This study evaluated the effectiveness of surgically releasing elbow flexion contractures exceeding 30° through partial tenotomy of the brachialis and biceps brachii muscles, along with a division of the lacertus fibrosus. We performed 36 anterior elbow releases on patients with injury to the upper trunk (C5-C6) of the brachial plexus and elbow flexion contractures between 30° and 80°. All releases involved lacertus fibrosus section and partial lengthening of the distal portion of the brachialis tendon. In severe cases, biceps brachii tenotomy was also performed. All participants had a minimum follow-up of 12 months and preoperative elbow flexion strength of at least grade 4 on the British Medical Research Council scale, with no deformities in the shape of the ulnohumeral joint or radial head subluxation. Following a mean follow-up of 41 months, the average extension gain was 31° (range, 10°-50°). All patients maintained their flexion strength. Except for two participants with weaker triceps, the mean elbow extension gain was sustained throughout the follow-up period. There were no major or minor complications or reinterventions in the study. Partial tenotomy of the brachialis and biceps brachii muscles, coupled with lacertus fibrosus section, is an effective treatment for elbow contractures exceeding 30° flexion. This method is successful in individuals with a functioning triceps brachii and elbow extension strength of at least grade 3 on the British Medical Research Council scale. Therapeutic IV.

Traction MRI of the Elbow: Age-Based Effects and Implications.

We previously reported that traction magnetic resonance imaging (MRI) of the elbow without arthrography increases the width of the radiocapitellar joint (RC) and improves articular cartilage visibility. However, the effects of axial traction on different age groups have not yet been evaluated. We hypothesized that the effect of traction would decrease as the participants' age increased. We enrolled 30 healthy volunteers, ten each in their 20s, 30s, and 40s. The male-to-female ratio in each age group was 1:1. Elbow MRI was performed without traction and with 3, 5, and 7 kg axial traction. We evaluated joint space width (JW), humeral articular cartilage visibility, and intraprocedural pain/discomfort. We measured JW and cartilage visibility at the RC and the lateral and medial thirds of the ulnohumeral joint. The older age groups exhibited narrower JWs without traction. Axial traction increased the JW and improved the visibility of the RC in all age groups. No significant differences were observed in the ulnohumeral joint's lateral or medial thirds, but pain and discomfort increased with heavier traction weights. For participants in their 20s and 30s, axial traction of 3 kg seemed appropriate, while 7 kg traction was considered for those in their 40s.

Osteoarthritis of Proximal Radioulnar Joint: Computed Tomography-Based Assessment and Associations with Clinical Findings.

Although many studies have focused on the degenerative changes of the ulnohumeral and radiohumeral joints in osteoarthritis (OA) of the elbow, the proximal radioulnar joint (PRUJ), which facilitates the pronation and supination motions of the forearm, has not been comprehensively evaluated. To assess the prevalence of PRUJ OA in patients diagnosed with OA of the elbow using computed tomography (CT) images and to establish an association between the CT findings and clinical manifestations. Cross-sectional study; Level of evidence, 3. Between 2010 and 2022, a total of 85 consecutive patients who were scheduled to undergo osteocapsular arthroplasty for OA of the elbow and had undergone preoperative CT imaging were included in the study. As a control group, 85 patients who underwent CT scans of the elbow for reasons other than OA of the elbow were selected and matched to patients in the OA group. CT findings of OA in the PRUJ, including osteophytes, joint space narrowing, subchondral cysts, and loose bodies, were evaluated. Inter- and intraobserver agreement analyses for CT findings were performed. The relationship between the CT findings of OA in the PRUJ and OA of the elbow classification systems (Broberg-Morrey, Hasting-Rettig, and Kwak) as well as clinical manifestations (range of motion [ROM], Mayo Elbow Performance Score, and visual analog scale for pain) were evaluated. Patients in the OA group showed osteophytes in the radial notch (81.2%), osteophytes in the radial head (45.9%), joint space narrowing (54.1%), loose bodies (25.9%), and subchondral cysts (23.5%) involving the PRUJ. Both the interobserver (κ = 0.866) and intraobserver agreements (κ = 0.933) for CT findings of PRUJ OA were almost perfect. The CT findings of PRUJ OA were associated with the severity of OA of the elbow in Cochran-Armitage Trend analysis (with Brogberg-Morray, r = -2.624, P = .011; with Hasting-Rettig, r = -3.421, P = .002; with Kwak, r = -2.266, P = .032). The presence of radial notch osteophytes restricted ROM in the flexion-extension arc and pronation-supination arc (P = .009 and P < .001, respectively). PRUJ OA could be identified using CT imaging and showed radial notch osteophytes, joint space narrowing, loose bodies within the joint space, and subchondral cysts. PRUJ OA was related to overall OA of the elbow and may contribute to reduced ROM in the elbow joint. Therefore, preoperative evaluation of PRUJ OA can aid in the surgical planning of osteocapsular arthroplasty for OA of the elbow.

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

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. 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. 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. 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 in cases with a positive grip and grind test and radiographic evidence of radiocapitellar OA. Level of evidence: IV.

Comparison of Terminal Elbow Extension between Humans and Baboons (Papio anubis).

It is assumed that hyperextension of the elbow joint beyond 0° in humans is due to local ligament and other soft tissue laxity. The common extant old-world olive baboon (Papio anubis), with a quadrupedal gait, commonly has a mild elbow joint flexion contracture. This study compares anatomic and functional roles of the olecranon-coronoid notch angle of the proximal ulna and the anterior direction of its opening on terminal elbow extension in humans and baboons. Active terminal elbow extension was measured in 211 elbows of skeletally mature humans using the neutral zero method. Passive elbow extension and radiographs were performed on 60 extremities of 30 anesthetized baboons. The mean olecranon-coronoid notch angle for humans and baboons was 22.2 ± 6.0° and 11.3 ± 3.2°, respectively (P < 0.001). Mixed effect regression analysis showed that the magnitude of the angle was a significant predictor of terminal elbow extension (P < 0.001) when accounting for species. Also, the causal mediation analysis showed that 18% of the difference in terminal elbow extension between species could be attributed to the olecranon-coronoid notch angle (P < 0.001). Anatomic dissection of 16 baboon arms showed that sectioning of all the anterior soft tissue structures increased mean terminal elbow extension from -18.2 ± 5.9° to -7.1 ± 6.0° and that further elbow extension was blocked primarily by the intact humeroulnar joint. The size of the notch angle and the positioning of its anterior proximal opening played a significant role in deciding terminal elbow extension in both species.

Increasing Severity of Radial Longitudinal Deficiency Correlates With the Degree of Proximal Ulnar Hypoplasia

Classification systems and treatment for children with radial longitudinal deficiency are classically focused on the hand and wrist. However, the elbow can affect the function of these patients secondary to stiffness or instability. The objective of this study was to determine if a correlation exists between severity of radial longitudinal deficiency (RLD) and degree of proximal ulnar hypoplasia. A single-institution retrospective review was performed at a pediatric hospital. One hundred elbows were identified in 72 patients who met the inclusion criteria. Measurements such as the coronoid height, olecranon coronoid angle (OCA), and the anterior coverage index were obtained from lateral radiographs of children with RLD. Ten elbows had posterior subluxation of the ulnohumeral joint radiographically. Eleven patients had thrombocytopenia absent radius (TAR) syndrome. There was a significant mean difference for OCA between RLD types. Type 4 RLD (mean [M]=17.9; standard deviation [SD]= 11.3) had a significantly lower OCA than type 0 (M=26.4; SD= 5.9) and type 1 (M= 31.0; SD= 5.0). A subanalysis of the 58 elbows with type 4 RLD demonstrated that those with TAR (n= 11) had significantly higher anterior coverage index total scores (M = 1.7; SD= 0.3) than those with type 4 without TAR (M = 1.5; SD= 0.2). The degree of proximal ulnar hypoplasia is correlated with increasing severity of RLD, with significantly lower OCA and coronoid height observed in the elbow radiographs of patients with type 4 RLD compared with type 0 and type 1. Children with TAR have less proximal ulnar dysplasia and higher anterior coverage index than children with type 4 RLD without associated TAR. Prognostic IV.

Ulnohumeral Cross-Pinning in the Management of Traumatic Elbow Instability

Traumatic elbow instability (subluxation and dislocation) represents a challenging clinical entity that can be complicated by persistent intraoperative instability after attempted stabilization or recurrent postoperative instability. Both static and dynamic supplemental stabilization procedures have been described for cases where fracture fixation and ligament repair fail to restore stability. There is a paucity of prior studies involving ulnohumeral cross-pinning (UCP), which is a type of static supplemental stabilization. Our purpose was to assess complications and outcomes after UCP. We reviewed all surgical cases involving primary and revision UCP for traumatic elbow instability at a single center from 2017-2023. Baseline demographics were recorded. Outcomes including radiographs, range of motion, patient-reported outcome measures, and surgical complications were analyzed. Fourteen patients undergoing UCP were included with a mean follow-up of 27 months. Five cross-pinnings (36%) were performed during revision procedures. Mean visual analog scale (VAS) pain, Disabilities of the Arm, Shoulder, and Hand (QuickDASH), and the Single Assessment Numeric Evaluation (SANE) scores were 2.4, 34, and 69, respectively. The mean flexion-extension and pronation-supination arcs were 114° and 140°, with 85% achieving at least a 100° arc for flexion and forearm rotation. Five patients (36%) had complications, all of which required reoperation. Two complications involved postoperative instability: one radial head subluxation and one radial head dislocation. Both occurred in revision UCP cases indicated for recurrent postoperative instability. Ulnohumeral cross-pinning for persistent and recurrent elbow instability results in maintained ulnohumeral joint alignment, functional arcs of elbow range of motion, and acceptable patient-reported outcome measures, particularly in the setting of a primary procedure indicated for persistent intraoperative instability. Ulnohumeral cross-pinning is a reasonable supplemental stabilization procedure for complex elbow instability. Therapeutic IV.

A neglected terrible triad of the elbow: A report case

Background: The terrible triad of the elbow was described in 1996 by Hotchkiss and is defined by severe trauma involving posterior dislocation of the olecrana, fracture of the radial head and coronoid process. Management has been a therapeutic challenge in recent decades due to its difficult treatment and poor prognosis. We report a case of a neglected terrible triad of the elbow in a 68-year-old patient following a road accident that occurred 1 month before admission. Methods: Mr B.M, 68 years old, presented to the emergency department for a closed trauma to his left elbow one month after his admission following a public road accident, it was a motorcyclist hit by a car, resulting in trauma to multiple points of impact including the skull, spine and left elbow. On the radiograph of the elbow face, there was a fracture of the radial head associated with a fracture of the coronoid process and posterior humeroolecranial dislocation. CT imaging made it possible to better visualize the fracture traits and classify them confirming the diagnosis of a terrible neglected triad of the elbow. Results: The patient received surgery under general anesthesia, with a lateral first of the elbow, a fracture of the radial head with a fracture of the coronoid process in cal, after removal of the cal, reduction of the fracture of the head with installation of a mini T-plate, reduction of the olecrane and arthrodesis of the ulno-humeral joint by 02 pins in cross. Post-operative immobilization by a brachio-antebrachio-palmar splint was recommended. Conclusion: The delay in taking charge of an unfortunate triad of the elbow engages the functional prognosis of the limb. Neglected fractures are still seen in our context and pose a real public health problem.

Youth Pitcher Fatigue: Medial Elbow Laxity, Ultrasonographic Assessment of Flexor-Pronator Mass Energy Depletion, and Association With Pitch Count.

Ulnar collateral ligament (UCL) injuries in youth pitchers continue to be concerning despite the institution of pitch count limits. Flexor-pronator mass fatigue can lead to diminished dynamic stability, resulting in greater stress on the UCL. To evaluate fatigue of the flexor-pronator mass by assessing changes in medial elbow laxity; noninvasively characterizing alterations in muscle glycogen; and identifying changes in subjective fatigue, strength, range of motion (ROM), pitching velocity, and accuracy with increasing pitches thrown by youth pitchers to their recommended 75-pitch count limit. It was hypothesized that, with increased pitches, medial elbow laxity would increase and that the glycogen content of the flexor-pronator mass would decrease. Descriptive laboratory study. Healthy male pitchers aged 10 years (n = 22) threw 3 sets of 25 pitches with 12 minutes between sets (3 timepoints). Bilateral ulnohumeral joint gapping was measured by applying a standardized valgus force and utilizing ultrasound imaging. Relative changes in muscle glycogen in the bilateral flexor carpi radialis (FCR), and the flexor digitorum superficialis/flexor carpi ulnaris (FDS/FCU) muscles were measured with ultrasound software and recorded as fuel percentiles. Additional measures obtained included subjective fatigue, strength, ROM, velocity, and accuracy. There were no differences in medial elbow joint-line gapping between the throwing and nonthrowing arms or between timepoints. The throwing arm demonstrated a significant decline in fuel percentile of the FCR from baseline to after 75 pitches (P = .05). There were no differences across timepoints for FDS/FCU fuel percentile values. Fatigue measurements for both arms were significantly higher at all timepoints compared with baseline (P≤ .03). Grip strength of the dominant arm after 75 pitches was decreased significantly compared with after 25 pitches (P = .02). Although an increase in medial elbow joint gapping was not demonstrated within the recommended 75 pitch count limit in 10-year-olds, a relative decrease in glycogen stores of the flexor-pronator mass did occur, as well as a decrease in grip strength, with increasing subjective fatigue. This study provides a foundation for further objective testing of physiologic changes that occur with pitching to better guide pitch count limits and improve the safety of young athletes.

Biomechanical evaluation of the modified lasso technique

BackgroundThe Terrible Triad of the elbow is a constellation of elbow dislocation, radial head fracture and coronoid process fracture. A common type of coronoid fracture documented with this triad is type II Regan-Morrey coronoid fractures. The preferred fixation method for this fracture type is the lasso technique, medial-lateral tunnel orientation being the traditional approach. Considering elbow anatomy, we saw an opportunity to potentially improve fixation by altering the suture lasso tunnel orientation to a proximal-distal orientation. HypothesisTwo tunnels in the proximal-distal direction would result in greater biomechanical stability as compared to the traditional lasso technique. Material and methodsA type 2 Regan-Morrey fracture was created in 12 fresh frozen cadaveric elbows at 50% of the coronoid height using an oscillating saw. The humero-ulnar joint was placed in 0 degrees flexion then loaded at a rate of 10mm/min to failure. ResultsThe control technique (medio-lateral tunnels) showed failure load of 150±81N that was not significantly different (p=0.825) than the 134±116N measured for the modified technique (distal-proximal tunnels). The portion of the load-displacement curve used to calculate stiffness was linear (R^2=0.94±0.04) with determination coefficients that did not differ between the two groups (p=0.351). For stiffness, we measured 17±13N/mm and 14±12N/mm respectively for control and modified techniques that did not result in a significant difference (p=0.674). ConclusionIn this attempt to improve the shortcomings of the lasso technique, we found that changing from medio-lateral to proximal-distal drilling directions did not result in an appreciable biomechanical benefit. Level of evidenceBasic science study; Biomechanics.

Digital smart internal fixation surgery for coronal process basal fracture with normal joint spaces or radius-shortening: Occult factor of radius-ulna load sharing

BackgroundReasonable postoperative humeroradial and humeroulnar joint spaces maybe an important indicator in biomechanical stability of smart internal fixation surgery for coronoid process basal fractures (CPBF). The aim of this study is to compare elbow articular stresses and elbow-forearm stability under smart internal fixations for the CPBF between normal elbow joint spaces and radius-shortening, and to determine the occult factor of radius-ulna load sharing. MethodsCT images of 70 volunteers with intact elbow joints were retrospectively collected for accurate three-dimensional reconstruction to measure the longitudinal and transverse joint spaces. Two groups of ten finite element (FE) models were established prospectively between normal joint space and radius-shortening with 2.0 mm, including intact elbow joint and forearm, elbow-forearm with CPBF trauma, anterior or posterior double screws-cancellous bone fixation, mini-plate-cancellous bone fixation. Three sets of physiological loads (compression, valgus, varus) were used for FE intelligent calculation, FE model verification, and biomechanical and motion analysis. ResultsThe stress distribution between coronoid process and radial head, compression displacements and valgus angles of elbow-forearm in the three smart fixation models of the normal joint spaces were close to those of corresponding intact elbow model, but were significantly different from those of preoperative CPBF models and fixed radius-shortening models. The maximum stresses of three smart fixation instrument models of normal joint spaces were significantly smaller than those of the corresponding fixed radius-shortening models. ConclusionsOn the basis of the existing trauma of the elbow-forearm system in clinical practice, which is a dominant factor affecting radius-ulna load sharing, the elbow joint longitudinal space has been found to be the occult factor affecting radius-ulna load sharing. The stability and load sharing of radius and ulna after three kinds of smart fixations of the CPBF is not only related to the anatomical and biomechanical stability principles of smart internal fixations, but also closely related to postoperative elbow joint longitudinal space.

Impact of Climate on Stress Ultrasound Findings of the Elbow Ulnar Collateral Ligament in Professional Baseball Pitchers: An 18-Year Study.

The ulnar collateral ligament (UCL) is the primary soft tissue stabilizer to valgus stress in the elbow and is placed under this valgus stress during the throwing motion. Although there are known risk factors for UCL injury, it is unknown whether the UCL undergoes adaptive changes in athletes from different climates. To compare elbow stress ultrasound (SUS) findings between professional baseball pitchers from warm climates versus cold climates and assess significant differences in adaptive and morphologic changes in the UCL. Cross-sectional study; Level of evidence, 3. Dynamic SUS evaluations were performed over 18 years on the dominant and nondominant arms of 643 professional pitchers from warm and cold climates as determined by the player's country/state of origin. Studies were compared with respect to relative UCL thickness (dominant arm vs nondominant arm), relative glenohumeral joint laxity (joint space distance under stress vs joint space distance at rest), and the presence of morphologic changes such as tears or calcifications. In addition, a subgroup analysis was performed to compare the progression of SUS findings over 3 years in players with sequential yearly data. Players from warmer climates had significantly greater relative UCL thicknesses than players from colder climates (1.75 vs 1.50 mm, respectively; P = .047). There were no differences between these 2 groups in terms of relative ulnohumeral joint laxity (P = .201), presence of morphologic changes (P = .433), 3-year progression of relative UCL thickness (P = .748), or relative joint laxity (P = .904). Professional pitchers from warm climates had a greater side-to-side difference in UCL thickness between the dominant and nondominant arms. This may be due to the potential for year-round throwing among baseball players from warm climates. There was no difference in laxity, thickness progression, laxity progression, or the presence of additional morphologic changes.

Optimization of Traction Magnetic Resonance Imaging to Improve Visibility of the Elbow Cartilage.

We previously reported that elbow magnetic resonance imaging (MRI) with 7 kg traction increases the joint space width of the radiocapitellar joint and improves articular cartilage visibility without arthrography. However, the optimal traction weight remains unclear. We assessed the effects of different traction weights on elbow MRI in 30 healthy volunteers. Elbow MRI was performed without traction and with 3, 5, and 7 kg axial tractions. The joint space width, humeral articular cartilage outline visibility, and intraprocedural pain/discomfort were evaluated. The joint and cartilage parameters were measured at the radiocapitellar joint and the lateral and medial thirds of the ulnohumeral joint. At the radiocapitellar joint, the joint space width increased significantly with traction. The cartilage outline visibility significantly increased with traction, with no significant differences among the traction weights. No significant result was observed at the lateral and medial thirds of the ulnohumeral joint. Pain and discomfort significantly increased as we used heavier traction weights. Elbow MRI with 3 kg traction showed sufficient effects similar to those observed with 7 kg traction with minimal pain and discomfort. There was no difference in the effect of traction between male and female participants. This procedure may enable enhanced visualization of intra-articular elbow injuries.

The Utility of Stress Ultrasound in Identifying Risk Factors for Elbow Ulnar Collateral Ligament Tear: A Longitudinal Study of 203 Professional Baseball Players

Background: Injuries to the medial ulnar collateral ligament (UCL) are common among baseball pitchers due to repetitive stress on the soft tissue stabilizers of the elbow during pitching. Dynamic stress ultrasound (SUS) can be used to evaluate the UCL and ulnohumeral joint to identify anatomic risk factors of those who will require UCL reconstruction (UCLR). Purpose: To determine whether any adaptive or morphological changes detectable on SUS can predict injury to the UCL in professional baseball pitchers. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 203 professional baseball pitchers who underwent SUS at preseason training sessions over the course of 18 years were categorized into 1 of 2 groups: those without a history of shoulder, arm, elbow, or forearm surgery or injuries (healthy cohort; n = 184) and those who underwent UCLR the same season as SUS (UCLR cohort; n = 19). Ligament thickness, joint spacing, and laxity were compared. An additional matched cohort analysis was conducted using 10 players from each group to detect differences in the progression of UCL and ulnohumeral joint measures in the year before injury. Results: The UCLR cohort, when compared with the healthy cohort, had higher relative (ie, nondominant-side measurements subtracted from dominant-side measurements) resting ulnohumeral joint space (median, 0.50 vs 0.20 mm, respectively; P = .006) and higher rates of hypoechoic foci (57.9% vs 30.4%, respectively; P = .030). Players of both groups had similar dominant UCL thickness (P = .161), ulnohumeral joint space at rest (P = .321), space under stress (P = .498), and laxity (P = .796). Groups did not differ in terms of relative UCL thickness, ulnohumeral joint space under stress, or relative laxity. In the year before UCL injury, the UCLR cohort, compared with the matched healthy cohort, had a greater increase in mean dominant UCL thickness (0.94 vs –0.60 mm, respectively; P = .038) and a greater increase in relative median UCL thickness (1.35 vs –0.35 mm, respectively; P = .045). Players in the healthy cohort were statistically older than those in the UCLR cohort (23 vs 22 years, respectively; P = .004). No differences in ulnohumeral stress spacing or laxity were detected. Conclusion: SUS of players who underwent UCLR demonstrated a progressive increase in UCL thickness over 1 year, higher rates of hypoechoic foci, and increased ulnohumeral rest space compared with SUS of uninjured players.

Dynamic Stress Ultrasound Assessment of Professional Baseball Players’ Elbows After Ulnar Collateral Ligament Reconstruction

Background: There is a paucity of data analyzing dynamic stress ultrasound (SUS) findings in elite pitchers who have undergone ulnar collateral ligament (UCL) reconstruction (UCLR) and returned to sport. Purpose: To identify longitudinal, perioperative changes in the elbows of professional baseball pitchers who have undergone UCLR and to compare these findings with a matched cohort of healthy pitchers. Study Design: Cohort study; Level of evidence, 3. Methods: This study used prospectively collected data from dynamic elbow SUS analyses of professional baseball pitchers within a single Major League Baseball organization. Pitchers were divided into 2 cohorts: a UCLR cohort and healthy cohort. The UCLR cohort eligibility included availability of (1) SUS from preseason of injury/UCLR and (2) SUS from ≥2 years after surgery. These players were 1:1 matched to players with no history of upper extremity injury to form the healthy cohort. Ligament thickness and ulnohumeral joint space at rest and under stress were directly measured. Joint laxity was calculated by subtracting joint space at rest from joint space under stress. The term “relative” was used to describe calculated differences where nondominant measurements were subtracted from dominant-side measurements. Results: Eight pitchers were included in the UCLR group and matched to 8 healthy pitchers (mean age at initial SUS examination, 19.6 years). At a minimum follow-up of 2 years, there were no significant differences between groups in terms of relative or dominant arm rest space, stress space, or laxity. Longitudinally (final measurements – baseline measurements), the mean relative ulnohumeral rest space decreased in the UCLR group and increased in the healthy group (–0.36 mm vs +0.50 mm; P = .032). The finding of increased UCL thickness in the UCLR group was expected, as UCL grafts are typically thicker than native ligaments. Conclusion: Ulnhohumeral joint stability was achieved after UCLR as indicated by similar rest space, stress space, and joint laxity in dominant arms compared with a matched healthy cohort. A significant decrease in relative rest space after UCLR may represent the achievement of stability in surgery patients. Alternatively, the increase in ulnohumeral rest space seen in the healthy cohort may represent adaptive changes from pitching at a professional level.

Finite element analysis of a customized coronoid prosthesis for traumatic coronoid deficiency

BackgroundTraumatic coronoid deficiency with persistent elbow instability is a challenging condition. Autologous bone graft reconstruction is often associated with a range of additional clinical problems and the outcome is often unpredictable. The purpose of this study was to design a prosthetic device that can reconstruct coronoid deficiency of any height and to evaluate its mechanical properties using finite element analysis. Materials and MethodsA customized coronoid prosthesis was designed based on image registration, automatic measurement and computer-aided design. After pilot study and sample size calculation, image data collected from six patients who underwent bilateral complete upper extremity CT scans were reconstructed. The test was divided into three groups: coronoid intact, prosthesis and autograft. Regan-Morrey type II and autologous olecranon osteotomy models were established. The prosthesis and autogenous olecranon were assembled to the coronoid base. Stress was applied axially along the proximal humeral diaphysis and implant micromotion and contact mechanics of the humeroulnar joint were measured at 30°, 45°, 60° and 90° of joint flexion respectively. ResultsAt all flexion angles, the maximum stress on the coronoid articular surface was significantly reduced in the prosthesis and autograft groups, with the reduction being more significant in the latter (P < 0.001). With increasing flexion, the maximum stress at the coronoid articular surface increased significantly after autograft reconstruction (7.2 to 68 MPa, P < 0.001), whereas the humeroulnar joint obtained a similar contact mechanics pattern to that of the control group after prosthetic reconstruction. As the flexion angle increased, the relative micromotion of both the prosthesis and autograft increased significantly (0.5-1.6 vs 0.2-1.2, Pmeasure time < 0.001, Pgroups < 0.001). Contact pressure and center-of-force paths of the humeroulnar joint experience abrupt stress changes at approximately 60° of flexion. ConclusionThe contact stress pattern in the humeroulnar joint is similar in prosthesis and intact coronoid groups. Autograft reconstruction increases contact stresses at the articular surface and alters the joint center-of-force path. The “stress surge phenomenon” in the humeroulnar joint surface before and after 60° of flexion may be one of the mechanisms of traumatic elbow degeneration.

Association Between Draft Order and Stress Sonography of the Ulnar Collateral Ligament of the Elbow in Professional Baseball Pitchers: An 18-Year Study

Background: The Major League Baseball (MLB) draft is a common route for players to enter professional baseball in the United States. Players taken in earlier rounds are typically higher-performing players. When looking at pitchers specifically, higher performance at the amateur level may be associated with an increased frequency of adaptive change in the throwing elbow. Purpose: To determine whether pitchers taken in earlier rounds of the MLB draft have a greater frequency or extent of pathological change in the elbow, as measured by dynamic stress ultrasound. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Dynamic stress ultrasounds (SUSs) were performed over 18 years on the dominant and nondominant arms of 651 professional pitchers. The 383 drafted players were grouped according to the round in which they were drafted (rounds 1-5, 6-10, 11-20, 21+). Groups were compared with respect to “relative” ulnar collateral ligament (UCL) thickness (dominant-nondominant), relative ulnohumeral joint laxity (joint space distance under stress minus joint space at rest), and the presence of pathology (calcifications, tears, hypoechoic foci, osteophytes). In addition, a subgroup analysis was done to compare the progression of SUS findings over 3 years in players for which data were available. Results: Draft round groups did not differ by age, number of previous spring training, or handedness. Comparing baseline measurements, there was no significant relationship between draft round and relative UCL thickness (P = .932), relative laxity (P = .996), or presence of pathology detectable on SUS (P = .642). However, increased relative UCL thickness was significantly associated with the presence of pathology on SUS (odds ratio, 1.45; 95% CI, 1.26-1.69; P < .001). Longitudinally, there was no significant relationship between draft round and 3-year progression of relative laxity, relative UCL thickness, or clinical progression of pathology. Conclusion: Higher-performing pitchers are drafted earlier in the MLB draft. This may be attributable to peak pitch velocity, in-game performance, visibility gained during player showcases, or any number of other sport-specific variables. However, despite this, there was no significant relationship between draft round and adaptive changes to the elbow or specific properties of the UCL on stress ultrasound.

Intraoperative visualization of the posterolateral ulnohumeral joint space is reliable to indicate overlengthening in radial head arthroplasty.

Avoiding overlengthening in radial head arthroplasty (RHA) is essential for the prognosis of the elbow joint. An overlengthening from 2mm is visible due to widening of the anterolateral ulnohumeral joint space but intraoperatively, this particular joint space is difficult to visualize. The commonly used Kocher approach allows visualization of the posterolateral joint space without additional instruments or further surgical release of the already unstable elbow. The aim of our study was to investigate whether the visualization of the posterolateral joint space is also a reliable method to indicate overlengthening in RHA. RHA was performed in five human cadaveric specimens with the forearm, wrist, and hand intact. The lateral ligament complex was detached and an anatomic transosseous refixation was performed. Six stages of implantation heights were documented: native joint (1), RHA at the anatomic height (2), + 2mm (3), + 4mm (4), + 6mm (5) and -2mm (6). Macroscopic measurement and digital image analysis of the posterolateral and anterolateral ulnohumeral joint spaces were performed. All stages of overlengthening showed a significant increase in posterolateral and anterolateral joint space widening (p < 0.05). The posterior and anterior joint space showed excellent intraclass correlation. Visualization of the posterolateral aspect of the ulnohumeral joint space is a reliable indicator for overlengthening in RHA without further compromising an already unstable elbow. Correlation to the findings of the anterolateral ulnohumeral joint space in different implants leads to the assumption that visualization of either the anterior or posterior ulnohumeral joint space is universally applicable to determine overlengthening in RHA, regardless of the type of the radial head implant.